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R/E/P => R/E/P Archives => Brad Blackwood => Topic started by: Viitalahde on March 07, 2009, 09:04:46 am

Title: For those with passive monitor attenuators..
Post by: Viitalahde on March 07, 2009, 09:04:46 am
What are you using?

There will be a 3rd and final console I'm about to build. I want to improve the mechanical quality by going from Elma switches to the great, sturdy Russian switches I've been using lately.

But most of all I want a bridged-T attenuator. Right now I have a 5k L-pad attenuator, 23x 2dB steps + dim. The new one will be built on a Shallco. I reckon something like 2k5 would be a place to start with Z values.

Since this is going get into general console discussion anyway, let me ask one more thing:

How many of you are using something more extended as a "console" than a monitor volume controller?

I switched to the current console about two years ago, and I personally love having all the bypasses at one single place. The amount of cable is for sure larger with all these sends & returns, but it's not often I have everything patched-in.
Title: Re: For those with passive monitor attenuators..
Post by: mastertone on March 07, 2009, 11:39:46 am
Hi Jaakko, does shallco offer ready made attenuators or just the switches?

Im pretty much in the same situation, but ive been lookin at the goldpoint att.
And my monitor section will have more functions than now.
Title: Re: For those with passive monitor attenuators..
Post by: Andrew Hamilton on March 07, 2009, 12:48:45 pm
Shallco offers both ready-made attenuators at custom Z values, as well as the naked switches.  I'm using a Shallco-made 5k Ohm bridged H-pad (which is a differential path T pad).  According to Nelson Pass, the Pass Labs amps with SuperSymmetry actually sound better with differential sources, rather than single-ended ones, and he confessed to me that he has never been in a mastering studio that wasn't entirely wired differntially.

The use of bridged-T or -H pad lets you minimize the number of resistors in series to 2 (per leg), at all steps of the switch.  So, very quiet settings will not have more Johnson noise (; than higher loudness settings, as is the case with series-types. Also, the impedance seen by both the source and the destination does not change when switching steps with this type of circuit, so one can focus on the sound of the loudness differences without much interference from other voodoo.

The Lavry M•DA-824 can drive a 600 Ohm load, and Dan told me that 2k Ohms would be the theoretically ideal loading for that DAC.  So, I had a 2k Ohm balanced passive attenuator made by GoldPoint Audio which worked nicely for a while.  I preferred the sound of the CraneSong Avocet to that.  But after DC insisted that passive, when loaded properly, is "essentially blameless," I splurged for the $600 Shallco bridged H.  Of course DC was correct - at least according to my listening tests.  The Shallco 5k H pad is sonically invisible!  Loving the lack of color.

After I sold the Avocet, I had over $1500 left over to buy other things with.  I did implement a source switch, as well as an independent mute switch for left and right channels.  5k is what DC recommended as a good compromise between performance and flexibility,  and it is not much worse than 2k for human hearing requirements, as long as the cable is ultra~low capacitance and the leads are as short as necessary to reach the amps, and 5k does provide a little extra resistance for wimpy sources one might wish to audition on the same setup.  (Fwiw, I'm all Mogami 3080 right now, which is 14 pF/foot).  





Andrew




P. S., I'd like to know if anyone has modified their differential inputs and outputs on mastering gear to be single-ended and what was entailed as well as any gotchas.... I was once instructed to bypass the balancing stage (as well as anti-RFI components) of the inputs of a Dominator II by one of our resident electronics gurus, fwiw.  This was only to improve the purity of the sound, which I think it did.  But, it was on a multiband clipping limiter, so sound quality is a relative thing, right?  

Since mastering studios are usually quiet and specialized environments, why is so much mastering equipment differential?  There are a few notable exceptions for off-the-shelf gear, such as that made by Pendulum, which is deliberately single-ended.


 
Title: Re: For those with passive monitor attenuators..
Post by: cass anawaty on March 07, 2009, 03:53:58 pm
I use the Goldpoint SA1X.  Very happy with it.
Title: Re: For those with passive monitor attenuators..
Post by: Gold on March 07, 2009, 03:58:45 pm
I recently had a 10k:5k (full) H pad made by Shallco. I asked for a bridged H and they quoted me on that. Then they realized they only knew how to do an unequal impedance as a full H. So that is what I got. Apparently I was the only one who ever asked for that. A 12 deck switch for stereo. I got 30 position with 1.5dB per step. It's very impressive looking. I have a big knob for it.

I don't have it installed yet. I have meters on the way. They are all custom order Sifams. VU, PPM and correlation meter. All white background with black scales. The correlation meter is a vertical orientation edge meter. I got gray masks for the Clarity series VU and PPM and extra bezels for the edge meter which I will attempt to paint gray. It should be very pretty.

For bypass the grand plan is to have relays in the gear but control centrally located.
Title: Re: For those with passive monitor attenuators..
Post by: dcollins on March 07, 2009, 04:32:37 pm
Viitalahde wrote on Sat, 07 March 2009 06:04

What are you using?



Shallco 2k5 bridged T.

Quote:


Since this is going get into general console discussion anyway, let me ask one more thing:

How many of you are using something more extended as a "console" than a monitor volume controller?



3 monitor inputs and 3 insert points.  Of which I use one of each on a normal basis.


DC
Title: Re: For those with passive monitor attenuators..
Post by: bblackwood on March 07, 2009, 10:01:02 pm
dcollins wrote on Sat, 07 March 2009 15:32

Viitalahde wrote on Sat, 07 March 2009 06:04

What are you using?



Shallco 2k5 bridged T.

Ditto (go figure).

Quote:


Since this is going get into general console discussion anyway, let me ask one more thing:

How many of you are using something more extended as a "console" than a monitor volume controller?


Six sources, seven monitor positions, six inserts.
Title: Re: For those with passive monitor attenuators..
Post by: Andrew Hamilton on March 08, 2009, 01:43:30 am
2.5k? Oh, DC...  My 5k system craps out at 227 kHz. );  

(Or, do I add the amp's input Z to that of the attenuator?  If so, I'm actually down at 42 kHz before I enter the cross overs)

You know, 1/2πRC...    My feeling is that I would not add the amp's 22k Ohm input Z to the 5k Ohms of the attenuator, because the resistive part of the amp's impedance is _after_ the capacitative part of the network (i.e., there's no more cable once it hits the amp).    However, I have read people to write that one must factor in all the Z's in each circuit...  





Andrew
Title: Re: For those with passive monitor attenuators..
Post by: Viitalahde on March 16, 2009, 06:16:39 pm
Been thinking about this.

2k5 or 5k bridged-T sounds like a good route. I just bought some naked Shallcos off eBay, but we'll see if I get around designing my own attenuator or ordering one from Marchand.

I was looking at Dangerous Master earlier, and the three insert points got me curious. Makes sense to me. I could group pieces that usually go together behind one insert, and still use each piece's own bypass. Not all of my tools have a bypass (since it's in the console), but some do.

It's easy to go nuts with console design, when all I need is a simple one. The current one has pre-process attenuators, which I never use. The first one had a fancy L mono/mono/R mono switch, which could be handy but not really necessary.

Restrictions have always made me tick better.  
Title: Re: For those with passive monitor attenuators..
Post by: jdg on March 16, 2009, 07:00:53 pm
i am on rev 5 of mine. and i really simplified it.
6 source, 1 insert, 3 outputs. 5k attenuator

the one insert is now really just a global bypass for the whole process chain
Title: Re: For those with passive monitor attenuators..
Post by: Andrew Hamilton on June 28, 2009, 09:07:39 pm
After re-reading the Pass Labs X-350 manual, I think Nelson was trying to say that _he_ prefers balanced (i.e., balanced Z legs of differential pairs, as the) signals rather than single-ended, and that, _if_ one is using his amps and _not_ using a balanced source, then s/he is _not_ benefitting at all from his patented SuperSymmetry feature, which requires a balanced signal as source.  The distortions of each leg will not be appreciably reduced (though somewhat, yes), but the differential distortions will tend to cancel by over a factor of 10, when SuperSymmetry is "enabled."

Furthermore, if, as DC has often said, one's mastering studio is capable of dealing with single-ended signals without noise or RF, then there's no reason (or tends to be little reason?) to employ balancing receiver/driver circuits, which, in the absence of other maladies, can _only_ negatively impact the sound (if there is any impact at all).  Who needs SuperSymmetry in these rooms, after all?  And I think I can agree that the Pass amps sound more like a very clean tube amp, in terms of open-ness, when operated single-ended, as compared with differential-sourced.  

Even Nelson's manual states that simpler is always better, with an allusion to Occam's razor...   But he clearly intended the Pass X series to be operated in balanced installations and barely mentions the RCA inputs.   Interesting polyphase logic?

It is also curious that he was saying that he was unaware of any  single-ended implementations in mastering studios.  Maybe he thought I meant mixing studios?  

Fortunately (for me), a bridged H-pad can be used as a bridged T-pad.  If I wanna go balanced again for some reason, the extra decks are in place.  

Also, by using the M•DA-824 in unbalanced output mode, one gets another 6.02 dB attenuation free of charge.  (hehe)  



Andrew
Title: Re: For those with passive monitor attenuators..
Post by: bruno putzeys on June 29, 2009, 03:24:35 am
The best compromise is to keep differential inputs but remove any circuitry explicitly designed to make a symmetrical output, as it is unnecessary. Don't remove differential input circuitry, you really need it.

There's no reason for an output to have voltage symmetry. As soon as the hot and cold wires are driven by the same impedance, you have a balanced output, meaning that a differential input will be able to ignore any ground differential that may exist between boxes. The cold wire may simply be tied to signal ground with a build-out impedance equal to that of the driver. Voil
Title: Re: For those with passive monitor attenuators..
Post by: Viitalahde on July 16, 2009, 02:03:27 pm
Bruno has many fine points that anyone needs to read!

But I got an on-topic question since I'm designing a new console right now.

How are you people doing level-matched comparisons between the source and the processed, post-A/D audio? In my current console, I have no way of doing this, and I've simply been turning the monitor volume up & down.

This needs to be changed.

What I have in mind is that my "monitor source" switch in the new, passive console could have a "compare" -position, in which a variable, stepped attenuator is inserted to the DAW feed. The attenuator would be out in any other position.

Since my monitor attenuator is going to be bridged-T (2k5, most likely), I suppose I'll have to make the comparison attenuator of bridged-T type, too.
Title: Re: For those with passive monitor attenuators..
Post by: bblackwood on July 16, 2009, 02:24:16 pm
I turn the ceiling output down on the L2 to match.
Title: Re: For those with passive monitor attenuators..
Post by: Gold on July 16, 2009, 02:25:29 pm
Viitalahde wrote on Thu, 16 July 2009 14:03

 I've simply been turning the monitor volume up & down.

This needs to be changed.




That's what I do. I think it works well enough. To my mind it's mostly a Go/No Go test. An exact level match is impossible once more than a tiny amount of processing has been applied.
Title: Re: For those with passive monitor attenuators..
Post by: Viitalahde on July 16, 2009, 03:12:39 pm
Something just crossed my mind.. The comparison attenuator is clumsy, no way around it.

My converter upgrade is not completely done yet. While processing, I monitor the captured audio through the Lynx Two D/A. While editing, I'm on the HEDD DAC.

The built-in attenuator of the Lavry DA-10 has felt wrong for me since I've always used a passive attenuator, but this feature could be used for exactly this purpose. Previously I was sure I'd get a Blue D/A. Now I need to re-think. But maybe I'll just need to re-evaluate my working methods.

The new console is going to be great. I might post a simplified schematic, if you want.
Title: Re: For those with passive monitor attenuators..
Post by: dcollins on July 16, 2009, 03:15:32 pm
Gold wrote on Thu, 16 July 2009 11:25


That's what I do. I think it works well enough. To my mind it's mostly a Go/No Go test. An exact level match is impossible once more than a tiny amount of processing has been applied.



Same here.


DC
Title: Re: For those with passive monitor attenuators..
Post by: TotalSonic on July 16, 2009, 03:32:40 pm
dcollins wrote on Thu, 16 July 2009 15:15

Gold wrote on Thu, 16 July 2009 11:25


That's what I do. I think it works well enough. To my mind it's mostly a Go/No Go test. An exact level match is impossible once more than a tiny amount of processing has been applied.



Same here.


DC


After having worked this way about 5 years ago - and since then being able to do "a quick set by ear and it's close enough" level matched a/b's between processed and source paths with a single button push -  
there's no way in heck I'd ever go back to having to turn things up and down.  For me it's an absolute requirement for my studio.

I find it's especially important for me when there's characteristics of the original mix that I really want to make sure I'm preserving even though I'm using some processing to try and effect other elements of the mix - it just lets me do these comparisons free of the "louder is better" bias and while making sure I'm still keeping the integrity of the mix in tact.

Obviously OMMV!!

Best regards,
Steve Berson  

Title: Re: For those with passive monitor attenuators..
Post by: TotalSonic on July 16, 2009, 03:43:32 pm
Viitalahde wrote on Thu, 16 July 2009 15:12

Something just crossed my mind.. The comparison attenuator is clumsy, no way around it.

My converter upgrade is not completely done yet. While processing, I monitor the captured audio through the Lynx Two D/A. While editing, I'm on the HEDD DAC.

The built-in attenuator of the Lavry DA-10 has felt wrong for me since I've always used a passive attenuator, but this feature could be used for exactly this purpose. Previously I was sure I'd get a Blue D/A. Now I need to re-think.



It's the reason I still hold onto my older Lucid DA9624 as the monitor DAC for my capture DAW's loopback.  It has an onboard attenuator so I can just set the level to where I want it and then this gets fed to one of the inputs of my Coleman M3PHmkII monitor controller (which receives on another one of its inputs a direct feed from the source).  The stereo pot on the attenuator doesn't track perfectly but the differences in the positions varies only very subtly (no more than a 1/4dB - and with a few labelled positions that I've found are perfectly accurate).  I find that the downside's of the older conversion and the less than perfect tracking are more than offset for me being able to do really quick level matched a/b's.

Been meaning to upgrade the Lucid to something like a Lavry DA-11 (whose digitally controlled analog attenuator I believe would track better and would also allow for really accurate recalls) but this has been pushed back in favor of other studio upgrades to date.

Best regards,
Steve Berson
Title: Re: For those with passive monitor attenuators..
Post by: Viitalahde on July 16, 2009, 03:53:54 pm
This was a quick decision, thanks for the input. I'm omitting the comparison attenuator from the console - another fiddly feature in a console I wanted to simplify in the first place.

I'll either keep on turning them knobs or I'll buy a DA-10. Either way, doesn't affect the console.
Title: Re: For those with passive monitor attenuators..
Post by: Andrew Hamilton on July 17, 2009, 12:22:07 am
I appreciate the theoretical detail of Mr. Putzeys' post.  I have since spoken with another E.E., however, who explained that balanced inputs usually are very sensitive to imbalances in the two signal legs and other parts of the input Z.  So much so, that, for mere audio frequencies, it is often better to go single-ended by tying pin 3 to ground, unless you have serious hum or other noises that can be reduced by signaling "balanced."  According to my contact, the worst problems of unbalanced signaling affect very high frequencies, such as radio and higher.  

In any event, while I have recently tried all possible combinations of wiring that I know of, the RCA jacks on my power amp (still) sound better than the XLR's (no matter what type of source I give the XLR's).  Alas, most of the mastering quality devices with transformerless balanced outputs in my rack do not seem to be  compatible with lifting pin 3 on output - even if pin 3 is grounded on destination through a resistor of the value of the output Z of the driver.   I don't understand exactly why, but some topologies, such as the Lavry MDA824, or Maselec equipment, are just not willing to have the rules bent, as it were, in that particular way.  But, even with unbalanced sources, with pin 3 tied to ground, the Maselec stuff rejects about 120 dB of line noise, according to the manual.  The SpectraFoo noise floor of the whole chain looks practically identical to when I had everything strictly balanced.  

What Mr. Putzeys said, is obviously still sound engineering, in principle.  But, in the field, we have a variety of mutually-exclusive attributes to juggle.  Balanced noise rejection versus twice the hiss on gear that may have fancy(?)  balancing schemes.  Transformer galvanic isolation and euphonic distortion versus absolute polarity and grunge.  Also, as Bob K. pointed out, we want to be able to patch anything to anything, ideally.  But unless we always patch point to point, being careful to use the same output interconnect for the same output (because only it has the correct build-out resistor) and only use compatible gear, then we must embrace the compromise that works/sounds best to us.

Maybe it's a combination of loading issues (caused by slight imbalances in a sensitive circuit) or maybe it's the noise spectrum issue, which Glenn cited.  Or both, plus some other things....  Either way, single-ended signaling is sounding best, here.




Best regards,
   Andrew
Title: Re: For those with passive monitor attenuators..
Post by: Gold on July 17, 2009, 09:45:38 am
Andrew Hamilton wrote on Fri, 17 July 2009 00:22

 I have since spoken with another E.E., however, who explained that balanced inputs usually are very sensitive to imbalances in the two signal legs and other parts of the input Z.  So much so, that, for mere audio frequencies, it is often better to go single-ended


I know an unbalanced source impedance degrades CMRR. Degraded CMRR is still better than no CMRR AFAIK. What other problem(s) did your EE say it caused?
Title: Re: For those with passive monitor attenuators..
Post by: Andrew Hamilton on July 17, 2009, 05:29:58 pm
Hi Paul, Here's what the guy wrote me (I'll delete his name so that I don't get him in trouble, if'n he's said something incorrect.  Caveat lector.)  


"The important thing with balanced inputs is that the impedance of the two "legs" be as close to equal as possible to maintain the noise-rejection qualities of the balanced input. In the real world, the accuracy of the matching of the inputs is limited by a number of factors, including the accuracy of the two resistors in series with the inputs, and the two other resistors (feedback and non-inverting input-to-ground), as well as the source impedance.

There are many other considerations, depending on what frequency range you are looking at, like stray capacitance and inductance that can have a serious impact on noise rejection at supersonic frequencies, as well.

But for most contemporary equipment, with a balanced input in the range of 10-20kOhms and output impedance much less than 100 Ohms, the "mismatch" caused by connecting the "low" side of the source directly to ground (as versus the driven output) may very well be less significant than the difference in the input impedance due to normal tolerances in the input resistors of the balanced amp. It probably depends on whether the parts are super-high accuracy (like 0.1 percent tolerance) or are hand-selected/hand- adjusted.

...You would still need to keep the connection the same as for "balanced"- using shielded twisted-pair cable. If there is some low-level hum present, the shield can be disconnected at Pin 1 of the balanced input end of the cables if there is a good ground connection between the two pieces of gear other than this shield.

The difference in "source impedance" for the two signal pins (Pin 2 and Pin 3) in this case would be just a bit over that 0.1 percent range for a balanced input impedance of 10k Ohms."






Best regards,
    Andrew



(P.S., How's Tom?)




Title: Re: For those with passive monitor attenuators..
Post by: Gold on July 17, 2009, 08:16:58 pm
Andrew Hamilton wrote on Fri, 17 July 2009 17:29


But for most contemporary equipment, with a balanced input in the range of 10-20kOhms and output impedance much less than 100 Ohms, the "mismatch" caused by connecting the "low" side of the source directly to ground (as versus the driven output) may very well be less significant than the difference in the input impedance due to normal tolerances in the input resistors of the balanced amp. It probably depends on whether the parts are super-high accuracy (like 0.1 percent tolerance) or are hand-selected/hand- adjusted.



I can't see how normal 1% resistors found in most pro audio gear would be a worse common mode match than grounding a leg. They would have to be way off. I think you are giving to much weight to the "may very well be" part of the paragraph. The last part of the paragraph is referring to the input circuit. Whether it's good or bad an unbalanced source impedance will cause proportionally good or bad CMRR.
Title: Re: For those with passive monitor attenuators..
Post by: Andrew Hamilton on July 19, 2009, 08:03:25 am
Gold wrote on Fri, 17 July 2009 20:16

Andrew Hamilton wrote on Fri, 17 July 2009 17:29


But for most contemporary equipment, with a balanced input in the range of 10-20kOhms and output impedance much less than 100 Ohms, the "mismatch" caused by connecting the "low" side of the source directly to ground (as versus the driven output) may very well be less significant than the difference in the input impedance due to normal tolerances in the input resistors of the balanced amp. It probably depends on whether the parts are super-high accuracy (like 0.1 percent tolerance) or are hand-selected/hand- adjusted.



I can't see how normal 1% resistors found in most pro audio gear would be a worse common mode match than grounding a leg.



Well, Sir, he did say that you need 0.1% tolerance in the network to be spot-on... I should think that four [mere] 1.0% tolerance, non-cherry-picked, resistors are indeed capable of ending up way off the mark compared to "...only a little worse than 0.1%..." shouldn't I?  Maybe his 0.1% is too stringent to begin with.  

Regardless, my complaint with the system has never been CMRR, or at least not specifically line noise, itself.  It's a generally brighter sound, when balanced, and possibly a slight "brilliance" is added to the transients.  Is this what happens when CMRR degrades? This sounds more like a loading effect.  Or maybe there's something to the audibility of differential amp hiss, on a psychoacoustic level, at least... Or maybe my balanced input circuit is broken in some other way.  It was bought second-hand as a factory refurbished.  They might have not even tested the XLR's thinking most people would only use the RCA's who bought it second-hand.  My Dunlavy's are second-hand, too (or third!).   They had broken crossovers.  One of them had apparently been improperly assembled at DAL (missing a resistor).  The other had a resistor with a broken leg, rendering it, essentially AWOL from the network. I'm open to even spooky action at a distance as the culprit. (or not);

Can't do this double A/B/X blind.  Only 3rd-eye blind.  

Alas, I can not implement Mr. Putzeys' ideal balanced approach on either my amp or my console, ironically, because the designers of the gear that I happen to have* didn't trust us to know that we could brake the rules responsibly - that we could lift pin 3 on output as long as we remember to shunt (is it?) the inverting leg (say) of the load to ground by the amount of resistance determined by the driving amp's output Z.  And/Or/Instead, they came up with a proprietary scheme (at least one which is not publicly discussed) that allows any dummy (such as I) to use an off the shelf XLR interconnect, and use it to send either a traditionally (fully) balanced or an unbalanced one with excellent noise rejection qualities, either way.  At least this is what it seems like.  

Mr. Putzey's words are "Science" (as Ron Burgundy would put it),  and no one is disputing that.  But there's a locomotive analogy to Science.  Pure Research is the locomotive engine, which is 50 or more years ahead of any likely application.  I'm hopefully somewhere near a dining car, but I realize that it's way in the rear cars of the train.  

This audio mastering has so many debates.  Like, do I want to risk using a pinch roller in order to get rotating lifters?  Or do I want to suffer with stationary lifters and a slow wind and risk servo-snap in order not to have to deal with a pinch roller?  


ITB or signal jack?  Just when the domain converters are getting good, so is dsp (getting good).


Do I want more songs on my iPod at low rez, or do I want them to have better digital resolution, even if there will be forcibly fewer songs, due to the increased demand on storage capacity?

Do I want to go for bottom or for top (end)?  etc... (i.e., 15 or 30 ips).  Choice is nice.  But sometimes there is no satisfaction.  Sometimes, both choices are wrong, and there is no third way.  ):

Spend / Save


I'm just glad he didn't say unbalanced is for turkeys.    I'd have to introduce him to my distinguished e-Mentors on the Blackwood list.  (;



* M•DA-824; MEA-2; MLA-2; MPL-2...   But also, Bob's Trakkers, and possibly other transformerless active balanced stuff?  Just a caveat lector...



Andrew
Title: Re: For those with passive monitor attenuators..
Post by: Viitalahde on July 19, 2009, 10:12:35 am
Still thinking of level-matched (or at least a close matched!) comparison between the signals.

I'm monitoring through the DAW, but I quess I could also split the AES/EBU signal from my A/D for a dedicated post-A/D monitoring D/A. A Lundahl splitting transformer and a Lavry DA10 would be pretty ideal. The idea is just to have a more hard-ware method of monitoring than routing a software mixer.

Just going through a period of improving my working methods. Who knows where I'll end. But I like to do it from time to time.
Title: Re: For those with passive monitor attenuators..
Post by: Gold on July 19, 2009, 05:25:39 pm
Viitalahde wrote on Sun, 19 July 2009 10:12

Still thinking of level-matched (or at least a close matched!) comparison between the signals.

I'm monitoring through the DAW, but I quess I could also split the AES/EBU signal from my A/D for a dedicated post-A/D monitoring D/A. A Lundahl splitting transformer and a Lavry DA10 would be pretty ideal. The idea is just to have a more hard-ware method of monitoring than routing a software mixer.

Just going through a period of improving my working methods. Who knows where I'll end. But I like to do it from time to time.


I'm all for easy monitoring of sources. I use four dedicated D/A's and switch with the console. I just don't mind turning the volume knob. That's what it's there for. It's makes it a two hand job instead of a one hand job but I don't mind a little hard work.
Title: Re: For those with passive monitor attenuators..
Post by: mcsnare on July 20, 2009, 10:15:27 am
Viitalahde wrote on Sun, 19 July 2009 10:12

Still thinking of level-matched (or at least a close matched!) comparison between the signals.

I'm monitoring through the DAW, but I quess I could also split the AES/EBU signal from my A/D for a dedicated post-A/D monitoring D/A. A Lundahl splitting transformer and a Lavry DA10 would be pretty ideal. The idea is just to have a more hard-ware method of monitoring than routing a software mixer.

Just going through a period of improving my working methods. Who knows where I'll end. But I like to do it from time to time.


I know it sounds stupid, but having a very close level match between source and processed available with just a button made a huge diiference to me. I did the switch + volume knob for a long time and it's just not the same IMO.

Dave
Title: Re: For those with passive monitor attenuators..
Post by: David Glasser on July 20, 2009, 10:42:23 am
mcsnare wrote on Mon, 20 July 2009 08:15



I know it sounds stupid, but having a very close level match between source and processed available with just a button made a huge diiference to me.




I can't imagine working any other way.
Title: Re: For those with passive monitor attenuators..
Post by: lowland on July 20, 2009, 11:14:54 am
David Glasser wrote on Mon, 20 July 2009 15:42

mcsnare wrote on Mon, 20 July 2009 08:15



I know it sounds stupid, but having a very close level match between source and processed available with just a button made a huge diiference to me.




I can't imagine working any other way.


Me neither. In my case I run synced clips on adjacent streams in the DAW (one feeds the chain, the other is an 'au naturel' monitor) and switch between listening to source or destination with a hotkey. Any level boost in the chain is pulled back to match via the output fader of the TC 6000, my last processor. Once a satisfactory sound is arrived at I correct the level back to just under zero and press record, the monitor clip is then overwitten in real time.
Title: Re: For those with passive monitor attenuators..
Post by: Viitalahde on July 20, 2009, 12:24:02 pm
Been thinking, and I just might try the level-matched approach after all.

This is what I would do. DAW -> HEDD192 D/A -> analog processors -> HEDD192 A/D ..My current processing loop.

I'd buy a Lavry DA10 and split the AES/EBU signal from the A/D side of the HEDD192 and bring it to a separate monitoring position in my console for level-matched post-A/D comparisons.

So, while processing, I'd be monitoring off the Lavry and while editing I'd be on the HEDD192 D/A (which I need to upgrade to the latest ones!).

I suppose you could also take an S/PDIF output from my Lynx Two card and take it to the Lavry if you wanted to have an alternate D/A for monitoring while editing. But I was actually thinking of having a combination of HEDD & Lynx D/A's for this purpose - and the Lynxes set to 16bit, dithered.

Somehow this makes perfect sense in my workflow. One twist from a monitor source selector, some level-adjustment from the Lavry and you got a pre/post comparison on your hands. And no software routing hassle.

If all this failed and I got lost in the woods, I could still hook up the DA10 like normal people do and go back to loopback monitoring from the DAW.
Title: Re: For those with passive monitor attenuators..
Post by: Peter Beckmann on July 20, 2009, 12:53:52 pm
mcsnare wrote on Mon, 20 July 2009 15:15



I know it sounds stupid, but having a very close level match between source and processed available with just a button made a huge diiference to me. I did the switch + volume knob for a long time and it's just not the same IMO.

Dave


I totally agree.

I do the level match by running a duplicate track in Protools HD of the source material and routing it to different AES output. Then I have that connected to one of the other digital inputs on my Avocet. Bingo, instant switch between source and processed. I level match either in the Avocet, or since I have a Command 8 in front of me I can just push a fader up to match the level. Big plus for me is I'm monitoring it all thru the same D/A

Peter
Title: Re: For those with passive monitor attenuators..
Post by: Peter Beckmann on July 20, 2009, 12:53:53 pm
mcsnare wrote on Mon, 20 July 2009 15:15



I know it sounds stupid, but having a very close level match between source and processed available with just a button made a huge diiference to me. I did the switch + volume knob for a long time and it's just not the same IMO.

Dave


I totally agree.

I do the level match by running a duplicate track in Protools HD of the source material and routing it to different AES output. Then I have that connected to one of the other digital inputs on my Avocet. Bingo, instant switch between source and processed. I level match either in the Avocet, or since I have a Command 8 in front of me I can just push a fader up to match the level. Big plus for me is I'm monitoring it all thru the same D/A

Peter
Title: Re: For those with passive monitor attenuators..
Post by: SafeandSound on August 04, 2009, 04:19:46 pm
I use SM Pro Audio Nanopatch, simple, smooth, transparent.

Completely satisfied.
Title: Re: For those with passive monitor attenuators..
Post by: Ben F on August 04, 2009, 11:14:23 pm
Viitalahde wrote on Sun, 19 July 2009 23:42

Still thinking of level-matched (or at least a close matched!) comparison between the signals.




I think it is really important to make valid comparisons. This becomes really apparent when testing gear- 0.5dB difference and you go 'wow, sounds great'. Level matched you go 'meh'. It's very good for testing gear/chains in your spare time.

The Crookwood is great for this. I generally make level matched comparisons for the first few tracks to get the sound of the album, then match the rest of the tracks up to the ones already mastered rather than doing more level matched comparisons. It's all done with a flick of the pre/post switch, in 0.5dB relay steps. Where I used to work I had to adjust the volume and it drove me nuts.
Title: Re: For those with passive monitor attenuators..
Post by: Bob Olhsson on August 05, 2009, 12:49:39 am
mcsnare wrote on Mon, 20 July 2009 09:15

...having a very close level match between source and processed available with just a button made a huge diiference to me. I did the switch + volume knob for a long time and it's just not the same
Same here. It's stupid easy to hype yourself with volume.
Title: Re: For those with passive monitor attenuators..
Post by: Jerry Tubb on December 11, 2009, 02:01:24 am
Cass Anawaty wrote on Sat, 07 March 2009 14:53

I use the Goldpoint SA1X.  Very happy with it.


tom eaton wrote on Tue, 28 October 2008 21:03

Both of the prefabbed balanced Goldpoint boxes are less than $600 and are as clean and high end as you will ever need.


My Goldpoint SA4 arrived today, I'll be hooking it up this weekend.

(yes, for now I still run my monitor path unbalanced)

http://www.goldpt.com/sa4.html

Arn Roatcap was very quick with the customer service.

My trusty old McIntosh C32 preamp's switches are wearing out, with no direct replacements that I know of,

so I'm gonna give the Goldpoint a run, at least till we build a custom box with Shallco switches.

Comments?

Cheers - JT
Title: Re: For those with passive monitor attenuators..
Post by: lowland on December 11, 2009, 02:17:13 am
Jerry Tubb wrote on Fri, 11 December 2009 07:01

Cass Anawaty wrote on Sat, 07 March 2009 14:53

I use the Goldpoint SA1X.  Very happy with it.
My Goldpoint SA4 arrived today, I'll be hooking it up this weekend.



Please let us know how you get on, Jerry. It's likely to be an SA1X or the dual-output equivalent for me at some point.
Title: Re: For those with passive monitor attenuators..
Post by: fuse on December 11, 2009, 10:35:39 am
SPL Volume8
Simple, transparent and can do 5.1(+1) or 2.2 with an Prism Orpheus hooked up to it.
Title: Re: For those with passive monitor attenuators..
Post by: jdg on December 11, 2009, 11:46:56 am
i love the gold point stuff. arn is so extremely helpful, and his switches/attenuators are so easy to work with from a DIY standpoint (all my switches/attenuators or from him)

Title: Re: For those with passive monitor attenuators..
Post by: subvertbeats on December 11, 2009, 12:34:05 pm
Peter Beckmann wrote on Mon, 20 July 2009 17:53

mcsnare wrote on Mon, 20 July 2009 15:15



I know it sounds stupid, but having a very close level match between source and processed available with just a button made a huge diiference to me. I did the switch + volume knob for a long time and it's just not the same IMO.

Dave


I totally agree.

I do the level match by running a duplicate track in Protools HD of the source material and routing it to different AES output. Then I have that connected to one of the other digital inputs on my Avocet. Bingo, instant switch between source and processed. I level match either in the Avocet, or since I have a Command 8 in front of me I can just push a fader up to match the level. Big plus for me is I'm monitoring it all thru the same D/A

Peter



Hi Peter

Surely that equates to switch + volume knob?

Theres have been a few replies to Daves post, agreeing with him, but unless Im missing something (quite likely Smile ), the responses havent provided the same solution.

Dave, does this 'single button' solution have some kind of AGC going on?

Im trying to understand how this could work.

What I feel impedes my workflow (not in a major way, but still something Id like to avoid) is having to continually adjust the level compensation throughout the mastering process, as Im incrementally adding devices to the chain, as Im switching devices in and out etc.

Its the way Ive always worked, and I dont know a better way so happy to see this being discussed.

BTW I was going to buy a Goldpoint SA2X-I a few weeks back, running two stereo outputs from the Orpheus into it - the first being the clean unprocessed signal, the second being the master chain, and assign the Orpheus volume knob to adjust the post DA level of the master chain.
I havent proceeded yet as I dont think the granularity of level control from that Orpheus front panel knob is fine enough.
Ive put an enhancement request into Prism to optionally adjust the scale of that knob.

I enjoy these threads, always insightful to hear about others workflows.
Title: Re: For those with passive monitor attenuators..
Post by: Jerry Tubb on December 11, 2009, 01:08:40 pm
fuse wrote on Fri, 11 December 2009 09:35

SPL Volume8
Simple, transparent and can do 5.1(+1) or 2.2 with an Prism Orpheus hooked up to it.


I've got the SPL Surround Monitor Controller SMC 2489, it's a really good unit.

After a few years the knob and switches have started getting a little noisy. time for a disassemble & cleaning job.

afaik the switches on the Goldpoint are superior.

JT
Title: Re: For those with passive monitor attenuators..
Post by: cass anawaty on December 11, 2009, 01:25:26 pm
Jerry Tubb wrote on Fri, 11 December 2009 18:08

fuse wrote on Fri, 11 December 2009 09:35

SPL Volume8
Simple, transparent and can do 5.1(+1) or 2.2 with an Prism Orpheus hooked up to it.


I've got the SPL Surround Monitor Controller SMC 2489, it's a really good unit.

After a few years the knob and switches have started getting a little noisy. time for a disassemble & cleaning job.

afaik the switches on the Goldpoint are superior.

JT

I've got one of those as well.  The image shift at low volume levels drives me insane--does yours do that?
Title: Re: For those with passive monitor attenuators..
Post by: Andrew Hamilton on December 11, 2009, 01:35:04 pm
I do love the Elma selector switches that Arn sells.

For level match (in SSHD), I latch M/1 to M/2 and pull them down, as a linked pair, for digital attenuation of the monitor DAC - post DAW-reinput, and leave M3/M4 at Unity. At double-precise 24 bit integer, it's no twin-SHARC bus, like UltraInteractive uses, but at least, this way, the eq/comp improvement has to stand up to added quantization distortion (however subtle and/or canceled out by temporarily-inserted 16 bit dither).  Shocked

I like the purity of passive attenuation, but for trimming, unless you use amps for buffering, which can add coloration, you need to be very careful about the parallel addition of impedance.


When calculating the desired net impedance, I believe that one needs to take into account the input Z of each passive device in circuit, including that of the power amp. Also, one needs to put a numerary "1" above the series of reciprocal values of Z.

_______1_________

1/Za + 1/Zb + 1/Zc


Find out what the optimal load is for your DAC and tune the chain to match. It can be daunting to derive a combination of impedances that will work together, without changing the response, while you are trimming the voltage swings. In the days of power matching (in the studio), the impedances were all symmetrical, but the build up of transformer distortions was one of the price tags for ease of interconnection. Again, using amps, be they transistor-based, or valve, or IC, can add color that might possibly skew the level-matched comparisons, since, once the trimming is back out of circuit, the level is restored to master Unity, but whatever (masking or skewing) coloration had been added is also now eliminated.

How transparent are the amps in the Crookwood? Probably very much so. But, if a Charter Oak falls in the Crookwood, and it is level-matched to source, will anyone really hear what's happened? Or is it yet another perspective?


The source, when cranked up, is always going to have some extra kind of live-ness that limiting will detract somewhat from. So, if the source is too quiet for the client, start lifting... and maybe don't look back?



Andrew
Title: Re: For those with passive monitor attenuators..
Post by: Jerry Tubb on December 11, 2009, 09:45:07 pm
lowland wrote on Fri, 11 December 2009 01:17

Jerry Tubb wrote on Fri, 11 December 2009 07:01

Cass Anawaty wrote on Sat, 07 March 2009 14:53

I use the Goldpoint SA1X.  Very happy with it.
My Goldpoint SA4 arrived today, I'll be hooking it up this weekend.



Please let us know how you get on, Jerry. It's likely to be an SA1X or the dual-output equivalent for me at some point.


Hooked the Goldpoint unit up today, it simply sounds great! Highly recommended.

If your thinking about one of the units, go for it, you won't regret it... wish I'd done it years ago.

The Mode Switch functions I lost from replacing the C32 are easily duplicated in my DAWs by using the free BX-Solo plug-in.

Looks like I'll be relegating my McIntosh C32 to our listening room, and perhaps occasional use as a phono preamp.

Cass Anawaty wrote on Fri, 11 December 2009 12:25

Jerry Tubb wrote on Fri, 11 December 2009 18:08

I've got the SPL Surround Monitor Controller SMC 2489, it's a really good unit.

After a few years the knob and switches have started getting a little noisy. time for a disassemble & cleaning job.

afaik the switches on the Goldpoint are superior.

JT

I've got one of those as well.  The image shift at low volume levels drives me insane--does yours do that?


Yo Cap'n Cass!

Yeah at low levels it gets a little wiggly, but I rarely listen that low!

For the price it's hard to beat. I've been using my SPL only for 5.1 surround, had it for about 5 years.
So a little scratchiness after many ACL 5.1 projects is no biggie.
Time for a little explorative deconstruction & cleaning.

Cheers - JT
Title: Re: For those with passive monitor attenuators..
Post by: Jerry Tubb on December 11, 2009, 10:35:08 pm
TotalSonic wrote on Thu, 16 July 2009 14:43

It's the reason I still hold onto my older Lucid DA9624 as the monitor DAC for my capture DAW's loopback.  It has an onboard attenuator so I can just set the level to where I want it and then this gets fed to one of the inputs of my Coleman M3PHmkII monitor controller (which receives on another one of its inputs a direct feed from the source).  The stereo pot on the attenuator doesn't track perfectly but the differences in the positions varies only very subtly (no more than a 1/4dB - and with a few labelled positions that I've found are perfectly accurate).  I find that the downside's of the older conversion and the less than perfect tracking are more than offset for me being able to do really quick level matched a/b's.


Sounds like what I've been doing Steve, using the Lucid DA9624 for level "matched" comparisons from my Source DAW (yet another advantage of the dual DAW setup). The onboard pot on the Lucid gets a little scratchy when the humidity goes up... time for yet another "lube" job.

Cheers - JT
Title: Re: For those with passive monitor attenuators..
Post by: mcsnare on December 12, 2009, 04:03:02 pm
Quote:

Dave, does this 'single button' solution have some kind of AGC going on?

Im trying to understand how this could work.



Most mastering consoles (including the one I use) have a volume knob for the pre-process compare, sourced after the first input stage but before the inserts. After you get an idea of your basic printing level you A/B and set the volume to match. I might tweak it a few times after I dial in some processing, but the it's far easier to set it a few times and then hit a button al the other times you compare, than it is to hit a button AND try to adjust volume at the same time for all the times you compare. I do a lot of comparing.


Dave


Title: Re: For those with passive monitor attenuators..
Post by: Crispin HT on December 12, 2009, 08:15:07 pm
Hi Andrew,

Just a quick insight to how we at least manage the A/B trims.

We have an analogue monitor with a balanced passive attenuator calibrated in 0.25dB steps. This passive attenuator presents a constant impedance to the source. After this is a balanced active stage that isolates the attenuator from the affects of cables and loads, so that teh unit should sound the same no matter what room it's in.

The A/B system works by relay selecting a source and simultaneously altering the attenuation for that source.  This means that as you switch the monitor gain alters, but the path is identical, that is no extra electronics are switched in or out.

With our digital type consoles, the same DAC is used, and as the digital router changes source, the analogue attenuation post DAC changes as above.  In this way you are also using the same monitor DAC.

I can't say that we are truely transparent: nothing is. But we come quite close, and any colouration is constant, irrespective of source, destination or trim applied.

Hope this helps you visualise how our monitor A/B works.

Cheers
Crispin HT
http://www.crookwood.com
Title: Re: For those with passive monitor attenuators..
Post by: Crispin HT on December 12, 2009, 08:19:19 pm
Oh and forgot to say that the monitor trim is recalled each time you access that source, so you can A/B anything to anything else.

On some models we have a single button that allows you to flip between the source and output of the record path, so with a fast SRC based DAC, you just quickly toggle the button to A/B your main path.

Cheers
Crispin HT
http://www.crookwood.com
Title: Re: For those with passive monitor attenuators..
Post by: Andrew Hamilton on December 13, 2009, 02:42:35 pm
Crispin HT wrote on Sat, 12 December 2009 20:15

Hi Andrew,



Hi Crispin,

Crispin HT wrote on Sat, 12 December 2009 20:15


We have an analogue monitor with a balanced passive attenuator calibrated in 0.25dB steps.


Wow. That's subtle.  The Dunlavy monitor pairs are (originally)  matched to within 0.25 dB, fwiw.  Also, the new Sontec switches are offered with some steps having +/- 0.25 dB.

Crispin HT wrote


This passive attenuator presents a constant impedance to the source. After this is a balanced active stage that isolates the attenuator from the effects of cables and loads, so that the unit should sound the same no matter what room it's in.


thanks to buffering amps... |:

Crispin HT wrote


...This means that as you switch the monitor gain alters, but the path is identical, that is no extra electronics are switched in or out.


...at least you are consistent.  (;

Crispin HT wrote


With our digital type consoles, the same DAC is used, and as the digital router changes source, the analogue attenuation post DAC changes as above.  In this way you are also using the same monitor DAC.


I quite agree with this requirement.  Even the same make, model, and year DAC, calibrated to within 1/10 miliVolt, can have a subtle difference in sound that can attributed to the batch of components, or even, dare I allow, "expectation?"

My motley rig, using the Z-Sys detangler, and the input faders in SSHD, does permit the level-matched monitoring of the M3/M4  source from the same DAC as the M1/M2 destination.

Crispin HT wrote


I can't say that we are truly transparent: nothing is. But we come quite close, and any colouration is constant, irrespective of source, destination or trim applied.


Best of all, you are honest!  (:

Crispin HT wrote


Hope this helps you visualise how our monitor A/B works.



Indeed, it gives me renewed confidence in my Crookwood wishes (and, dreams, however "caviar").



Thank you,
    Andrew
Title: Re: For those with passive monitor attenuators..
Post by: subvertbeats on December 15, 2009, 04:01:26 am
mcsnare wrote on Sat, 12 December 2009 21:03

Quote:

Dave, does this 'single button' solution have some kind of AGC going on?

Im trying to understand how this could work.



Most mastering consoles (including the one I use) have a volume knob for the pre-process compare, sourced after the first input stage but before the inserts. After you get an idea of your basic printing level you A/B and set the volume to match. I might tweak it a few times after I dial in some processing, but the it's far easier to set it a few times and then hit a button al the other times you compare, than it is to hit a button AND try to adjust volume at the same time for all the times you compare. I do a lot of comparing.


Dave





Cheers Dave, yep thats where Im trying to get to.
Whilst saving for one of Crispins consoles, ill have to keep the pressure on Prism Sound to make the assignable volume knob more finely grained....then with one of the Goldpoint boxes I'd be there...