Viitalahde wrote on Sat, 10 July 2004 15:35 |
next year I'm going for a Klein&Hummel UE-100 tubed eq. |
Gold wrote on Sat, 10 July 2004 22:13 | ||
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bblackwood wrote on Sun, 11 July 2004 10:55 |
Well, I'm still deciding on the details, but do know that it will be:
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bblackwood wrote on Sun, 11 July 2004 16:12 |
990 footprint idea is golden, Bob. Good idea. |
malice wrote on Tue, 13 July 2004 08:28 |
I had this address of fair designed PSU, every voltage, several different powers, quite cheap ... I'll try to find the link malice |
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I would be interested in developing this topology to make a 4-band EQ with passive low and high bands with some discrete opamp gyrators for the 2 mid bands. |
dcollins wrote on Thu, 15 July 2004 03:26 |
In thinking about this, I was reminded of the old "saturable inductor" where you have in effect another input to the system. Used in ancient de-essers. Distortion is probably off the map. Can you cobb your own from existing parts, is the question. |
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Please tell more! What's the premise here? A DC bias on the inductor to put it into saturation earlier? How was it implemented as a de-esser? |
bblackwood wrote on Fri, 23 July 2004 12:33 |
Still trying to keep yup here, so little has been done, though I am bouncing ideas off of our own DC (and I'm dragging Dave Hill into it...). Updates as available. |
bblackwood wrote on Fri, 23 July 2004 21:33 |
Still trying to keep yup here, so little has been done, though I am bouncing ideas off of our own DC (and I'm dragging Dave Hill into it...). |
moogus wrote on Sat, 24 July 2004 10:20 |
This version also drives 6db more level thru the inductors than the old version, and reports suggest this has improved the eq's utility on program material. |
moogus wrote on Sat, 24 July 2004 09:20 |
I cant help myself from responding here. We just finished 2 mastering pultecs the other week, that are pretty darn close to what youre describing. 2 bands, with sepperate freqs (12) for cut and boost, in 0.5db steps to 5.5db. Switched bandwidth on high boost (inductive) from, well, fairly narrow to very very wide. |
lucey wrote on Sat, 24 July 2004 19:51 | ||
sounds good, is this something you can help us DIY or are you a manufacturer? |
moogus wrote on Sat, 24 July 2004 07:20 |
I cant help myself from responding here. |
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We just finished 2 mastering pultecs the other week, that are pretty darn close to what youre describing. |
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Using the JLM instrument opamp from the mastering console to give fully balanced i/o and provide the makeup gain, which runs on +/-24V, has +36 headroom, bandwidth from DC to above 10meg and plenty of zeros in the THD%. |
dcollins wrote on Sat, 24 July 2004 20:03 | ||
That sounds interesting. I'm a little scared about the >10MHz response though. I tend to go for something around -3 at 300kHz just because there is so much RF noise out there today. Arguably the recordings I have that sound the most "open" were done on gear that was positively struggling to be flat at 20k! But that's a story for another day... DC |
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DC, I don't know the JLM, but would you be satisfied with an opamp with feedback compensation so resulting frequency response was around -3 dB at 300 kHz? |
lucey wrote on Sat, 24 July 2004 19:51 |
Moogus works with a nice manufacturer in OZ, but maybe he is willing to participate ... Moogus ? malice |
dcollins wrote on Sun, 25 July 2004 10:03 | ||
What are you using for input, interstage and output transformers? Iow, just cause it has an inductor, does _not_ make it a Pultec!
That sounds interesting. I'm a little scared about the >10MHz response though. I tend to go for something around -3 at 300kHz just because there is so much RF noise out there today. Arguably the recordings I have that sound the most "open" were done on gear that was positively struggling to be flat at 20k! But that's a story for another day... DC |
dcollins wrote on Sun, 25 July 2004 10:34 | ||
bobkatz wrote on Sat, 24 July 2004 17:15
That's a good place to start the rolloff. When I'm calculating the feedback R/C it's always something from say 150k to 300k. For audio that is. That JLM stuff looks interesting, but I don't know how anyone can use that kind of output level. 90% of stuff is on +/- 15V rails so if your opamp is really swinging +/- 60 Volts, there's gonna be padding somewhere. The A/D converter chip wants to see like 2 Volts.... Since low noise is so easy to achieve nowdays, why not just run your system at low levels and get the headroom that way? DC |
moogus wrote on Sat, 24 July 2004 15:20 |
I cant help myself from responding here. We just finished 2 mastering pultecs the other week, that are pretty darn close to what youre describing. snipped Using the JLM instrument opamp from the mastering console to give fully balanced i/o and provide the makeup gain, which runs on +/-24V, has +36 headroom, bandwidth from DC to above 10meg and plenty of zeros in the THD%. M |
Terry Demol wrote on Mon, 26 July 2004 19:37 |
Hi Moogus, Is this with the JLM99V or as your instrument opamp description suggests, a fully balanced instrumentation amplifier Bal IP -> SE OP, or just the front end of an instrumentation amp ie; CM gain = x1 bal in bal out, or lastly, a fully balanced VG (current) IP such as Nelson Pass's "Supersymmetry"? Cheers, Terry |
bblackwood wrote on Tue, 27 July 2004 16:18 |
OK, I'm starting to like DC's three band Baxandall (with either IC or 990 size opamps) idea. I dunno, probably just as easy to implement, especially with PCBs (which we will have made - already have a great source). Thoughts? |
jfrigo wrote on Wed, 28 July 2004 13:52 |
Forgive a non-designer's question, but I thought the Baxandall circuit was a shelving filter, and three shelves would be a bit odd. Is there a peaking filter that is close enough in circuit design to still be called Baxandall? |
jfrigo wrote on Wed, 28 July 2004 19:52 | ||
Forgive a non-designer's question, but I thought the Baxandall circuit was a shelving filter, and three shelves would be a bit odd. Is there a peaking filter that is close enough in circuit design to still be called Baxandall? As I just use the things and don't design them, I'm in the dark here. Who can help? I'd think three broad peaking filters would be preferable for this particular project, but I guess two shelves and a mid peak would be OK too. This is starting to get interesting, so maybe I'll hop on board for this project. 990 size seems like a good idea as I'm interested in trying some Forssells in there. |
Techne wrote on Wed, 04 August 2004 14:10 |
My question may be a bit premature for this project, but i was wondering what opinions you DIY'ers have about chassis selection. Anyone have good/bad experience with any of the prefab boxes out there? Sorry if this is a bit OT. |
Terry Demol wrote on Wed, 28 July 2004 20:19 |
Yes, there are 3 band Banxandall peaking EQ circuits that work in NF loop of an inverting OPA. I'll dig one up and send a link tonight. |
jfrigo wrote on Thu, 05 August 2004 20:53 |
Brad, What's your preference? Apart from "whatever the group decides," which of those bar graphs contains your vote? |
bobkatz wrote on Wed, 11 August 2004 18:53 |
I vote for a midrange cut, too. How about something like the old Pultec where you could select boost or cut? And be sure to use a big toggle like one of those old vacuum cleaner switches. Anyone have Pultec blue paint |
hollywood_steve wrote on Wed, 11 August 2004 20:03 |
BTW, I think I gave props to Hammond chassis recently on here... i'm offically taking that back, not digging it AT ALL Curious what the problem is? I have used their 2RU & 3RU chassis without any problems. What happened? |
hollywood_steve wrote on Wed, 11 August 2004 17:03 |
BTW, I think I gave props to Hammond chassis recently on here... i'm offically taking that back, not digging it AT ALL Curious what the problem is? I have used their 2RU & 3RU chassis without any problems. What happened? |
JPRisus wrote on Wed, 11 August 2004 18:31 |
Brad, you mentioned you already had a PCB source lined up... any chance it's these guys? pcbexpress.com They look cool, priced them out for a DIY SSL comp I thought about trying a while back. |
theom wrote on Thu, 12 August 2004 10:04 |
How about a group buy of a cool blue engraved face plate. |
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Oh, and What will be the name of this EQ ? |
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How about the Blackwood 1? Are you too bashful for that brad? How about the EQ-BW-2 ? |
bblackwood wrote on Thu, 12 August 2004 09:56 |
OK, the consensus seems to be passive filter sections, 'boost' and cut on 2 bands (hi and lo freqs) with a midband cut, 990-style opamp factor. Again, I'll start crunching numbers ASAP and after everything is checked in Spice, somebody will do the board layout for us... |
chrisj wrote on Thu, 12 August 2004 13:22 |
I'm following this thread very closely as I'm expecting to eventually make a modular digital/analog hybrid console that sums the outputs of some DACs through discrete Pultec-esque circuits to analog outs, but I haven't the slightest desire to clone anything, just to make a decent passive EQ that does what I want. As such, this project is going to be terribly useful to me for study |
ammitsboel wrote on Sun, 24 October 2004 16:52 |
Why not make it as simple as possible, and do a passive design with no gain makeup? |
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Just a very simple passive design with 2 shelves so we can "shelve" the sound gently into brighter or darker...? And sent the audio level through as few as possible components! Then we use our other gear for gain make up(if needed). |
bblackwood wrote on Mon, 25 October 2004 20:54 |
Would be cool, but I think the values of the EQ would change according to the load. Someone correct me if I'm wrong here... |
Level wrote on Tue, 26 October 2004 06:19 |
Look at what can be sweetness in 0.5 dB swings up to 18dB for us hard corers. I like DC to 70hz @ 6dB +/- 18dB Vari/para 45-650hz ] Main 800hz Vari/para 370hz to 3.8K Ditto for 1.5 to 17K And a fully 6dB/oct centered at 14.5K HPF at 23hz and 70 LPF at 19K @ 12dB/oct and 38Khz (for DSD filter) +24dbFs @ 0.01THD is fine. |
bblackwood wrote on Tue, 26 October 2004 20:00 |
Why not do it as a true group DIY and have some of you guys help crunch some numbers? |
bblackwood wrote on Fri, 21 December 2007 09:44 |
I think I'm going to make this happen soon, if anyone is still interested. |
djwaudio wrote on Sat, 22 December 2007 10:39 | ||
I'll build one of these too. I could use a simple LCR EQ. How can I help? |
Gold wrote on Sat, 22 December 2007 20:16 |
If the object is a group build sort of thing I think it will have to be a kit. Design and make some PCB's and put together a Bill of Materials. If it's a schematic without layout I think it will be beyond the capabilities of most. |
bigaudioblowhard wrote on Sat, 22 December 2007 23:35 |
whats LCR? |
djwaudio wrote on Sun, 23 December 2007 01:46 | ||
L = inductor C= capacitor R= resistor |
David Glasser wrote on Sat, 29 December 2007 19:06 |
But only if it has blue LEDs. |
David Glasser wrote on Sat, 29 December 2007 18:06 |
I'm in. But only if it has blue LEDs. |
bblackwood wrote on Wed, 09 April 2008 13:47 |
Ok, this is cool - I had two guys volunteer to bang on the design a bit and also support those who need it during the build process, so I met with my tech today and we went over the basics. to keep this simple (and keep it as affordable as possible), we decided to skip the inductors, so it's shelf only, will allow for boost and cut at variable frequencies. Will have a solid state buffer and makeup amp, so interfacing won't be an issue. This should result in a very clean and transparent EQ that's good for overall shaping. Obviously if you want something more complex, it's up to you, but this will be the basic design. We can have a mod thread if people want to... More to come... |
David Glasser wrote on Wed, 09 April 2008 12:57 |
See if you can configure it so the gain stage can be a 2520/990/Forsell form factor. |
Jeff Baggett wrote on Wed, 27 August 2008 07:18 |
any progress on this? |
OLDTUBEY wrote on Wed, 28 January 2009 22:45 |
Yeah, Yeah, Yeah, I'm interested in participating! Yes, I know this is sort of late and is in response to a post submitted in 2004:)..... I have a little bit of experience with the building of both passive and active EQ's as well as other high end audio from the ground up. 'Been doing it since about 1974. The last company I worked with off and on since about '92 made some very good equipment. Their EQ's were considered by many to be the very best in the world and definitely regarded as the industry standard. Unfortunately my 'Boss' man as I call him started losing his mind several months ago and then one day just stopped communicating. There must be some sort of curse on that old school. Now I think that he/they may have dropped off the face of the Earth suddenly and left me holdin one of the bags:).....I was also a procurement agent for them for a number of years.....got about 30,000 pounds of the stuff in the basement....along with a whole bunch of extraordinarily hard to find three legged semiconductors.... that go into some little modules... I refer to them as the 'Motorola Diamonds'.... The 'Boss' keeps his dwindling inventory of em locked up in a Safe I think......have a few schematics too:)..... But I'm not gonna be around much longer.I was thinking that maybe I should sell this stuff while I'm still alive and give the money to a children's research hospital or something. But I'd really like to make sure that they've actually closed down, outta business and aren't just hiding from me, before I go and let the cat outta the bag. Otherwise they might come gunnin for me. Anybody know anything? Any ideas? Kind Regards, Gruntboy Alf from hillbilly heaven |
OLDTUBEY wrote on Thu, 29 January 2009 17:15 |
The last company I worked with off and on since about '92 made some very good equipment. Their EQ's were considered by many to be the very best in the world and definitely regarded as the industry standard. Unfortunately my 'Boss' man as I call him started losing his mind several months ago and then one day just stopped communicating. There must be some sort of curse on that old school. Now I think that he/they may have dropped off the face of the Earth suddenly and left me holdin one of the bags:)..... |
Steffen wrote on Mon, 30 March 2009 06:16 |
I just came over this thread lately and got inspired |
Steffen wrote on Mon, 30 March 2009 09:29 |
thanx guys! btw...an interesting observation (hope this isn´t old news) |
Steffen wrote on Mon, 30 March 2009 09:29 |
Steffen wrote on Mon, 30 March 2009 09:29 |
... I´d expect the manley MP or the gyraf in between these two extremes of interaction. if somebody is interested to evaluate let me know.. |
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Wow. How about 1/3 dB steps? Gorgeous build. |
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O.K., but the 2k and 500 Hz colors are backwards, right? |