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Author Topic: regulated power for tube mics-- impact on sound?  (Read 12034 times)

soapfoot

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Re: regulated power for tube mics-- impact on sound?
« Reply #15 on: January 19, 2011, 02:35:52 pm »

so no choke then?  Just RC pi filters?
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brad williams

ssltech

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Re: regulated power for tube mics-- impact on sound?
« Reply #16 on: January 19, 2011, 02:37:58 pm »

dbock wrote on Wed, 19 January 2011 14:21

BTW I appreciate Brad using his whole real name, but who is "ttown"?


Profile says "Terence Town".

The power supply as described sounds like a bad example... I don't know of ANY commercial tube mic power supplies which use op-amps for regulation.

If someone fits one as aftermarket, then that's THEIR mistake... just bad engineering.

Keith
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MDM (maxdimario) wrote on Fri, 16 November 2007 21:36

I have the feeling that I have more experience in my little finger than you do in your whole body about audio electronics..

David Bock

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Re: regulated power for tube mics-- impact on sound?
« Reply #17 on: January 19, 2011, 06:28:34 pm »

I thought people were supposed to use their real names on this forum. Having to look them up under profiles is a loophole that shouldn't be accepted.
The use of Real Names in the age of "power through internet anonymity" is one of the great features of this forum, and I would urge all posters to participate fully.  

piedpiper

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Re: regulated power for tube mics-- impact on sound?
« Reply #18 on: January 19, 2011, 06:36:36 pm »

a little ironic considering the marked similarity between your own user name and lack of signature in your posts and that of "ttown".

...and thanks for all the great info.

respectfully,
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Tim Britton

row, row, row your boat...

Dominick

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Re: regulated power for tube mics-- impact on sound?
« Reply #19 on: January 19, 2011, 06:51:53 pm »

Moderators could require you to register with your real full name on the new forums.
That would be a step in the right direction
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Dominick Costanzo

David Bock

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Re: regulated power for tube mics-- impact on sound?
« Reply #20 on: January 19, 2011, 07:31:45 pm »

Quote:

a little ironic considering the marked similarity between your own user name and lack of signature in your posts and that of "ttown".
I definitely take liberty assuming I'm a little more well known here than ttown. will change asap.

Jim Williams

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Re: regulated power for tube mics-- impact on sound?
« Reply #21 on: January 19, 2011, 08:16:05 pm »

Check with some of the design work on precision regulators done by Walter Jung of Analog Devices. He has published many papers on the subject of precision regulation for audio circuits.
Yes, they use precision opamps for the references. They are not a bad choice, but maybe one of the better ones.
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Jim Williams
Audio Upgrades

piedpiper

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Re: regulated power for tube mics-- impact on sound?
« Reply #22 on: January 19, 2011, 11:18:37 pm »

I hear you, David, and know who you are, of course, but I'm guessing that assuming everyone would might be an oversight. It's just that the similarity struck me as  funny and I couldn't resist mentioning it. Thanks for your gracious response.
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Tim Britton

row, row, row your boat...

ttown

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Re: regulated power for tube mics-- impact on sound?
« Reply #23 on: January 20, 2011, 02:12:17 am »

Sorry for the oversight guys, no need to read into things, I just forgot to sign the post.  

Also, not making any inferences about which PSUs use op-amps and which don't.  I was asked to give an example of how a PSU can influence audio output from a mic, and this is what I found when I opened a Russian-made PSU for an AC701 tube mic.  I stand by what I said regarding the comparison with the Drefahl PSU.  It was notably quieter than the Russian op-amp-based PSU.

... but let's not loose the woods for the trees here.  The point is that a PSU can influence a mic's audio quality.  I am no expert and have limited experience as I stated in my post above.

Thanks,
Terrence Town
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ssltech

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Re: regulated power for tube mics-- impact on sound?
« Reply #24 on: January 20, 2011, 08:07:28 am »

Jim Williams wrote

 Check with some of the design work on precision regulators done by Walter Jung of Analog Devices. He has published many papers on the subject of precision regulation for audio circuits.
Yes, they use precision opamps for the references. They are not a bad choice, but maybe one of the better ones.


A noisy, poorly designed supply shouldn't paint ALL of them with the same brush, but a good tube mic B+ PSU shouldn't require the convoluted hoop-leaping that an op-amp circuit would entail.

Keith
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MDM (maxdimario) wrote on Fri, 16 November 2007 21:36

I have the feeling that I have more experience in my little finger than you do in your whole body about audio electronics..

David Bock

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Re: regulated power for tube mics-- impact on sound?
« Reply #25 on: January 20, 2011, 01:50:02 pm »

Quote:

... but let's not loose the woods for the trees here. The point is that a PSU can influence a mic's audio quality. I am no expert and have limited experience as I stated in my post above.

Ahh, but that's the point, you  listened. One of the traps for audio design is believing in something's superiority before listening. I could write a whole paper on this but don't have time today.
Quote:

a good tube mic B+ PSU shouldn't require the convoluted hoop-leaping that an op-amp circuit would entail.

Definitely not required but has been (EAR, Blue,*) and can be done. Usually the op amp will be acting as a comparator against a voltage reference. If done well, there IS lower noise overall and a different response characteristic to the mic, which, is a matter of taste, not right and wrong (yes there is right and wrong in the world no apologies to Nietzsche).
*fwiw Korby, Bradley, and Hampton supplies are regulated but I don't recall if they use op amps.

R-AP.SCI

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Re: regulated power for tube mics-- impact on sound?
« Reply #26 on: January 21, 2011, 03:51:18 am »

Good day to all,

    I am currently experimenting with varying power supply topologies and have begun to employ the methodology stated by Mr.Williams employing the Jung precision regulators. In the heater section that is....(and tubed in the HV!!!...FUN). Thus far it most definitely has outperformed all traditional LM317 and like type 3pin chip regulators across the board...(in terms of noise etc) and I enjoy the sonic outcome. I will post definitive measurements when a final design has been achieved. I personally enjoy regulation of tube mic power supplies (not to say that other types aren't to be lauded, as some classic, beautiful sounding and legendary tube mics do not employ regulation).

    I also have liked the fairchild 1N4934 fast recovery diodes in rectification applications. Try those too!...(i'm a bit of sucker for overbuilding and experimentation)

    It is of course an entire circuit consideration and as far as I'm concerned one that can and does have sonic affects.

  I rather enjoy this thread as it (indirectly) addresses a many times overlooked section in the industry (sometimes, in my opinion, expressed in the vein of "does it work?"..."yes."..."does it screw anything up?"..."no."..."GREAT, DONE!")...or in the sense of it meeting a perfunctory electrical standard...and no further. If there isn't already, one of us should start a thread dedicated to the design considerations and implementation of power supplies in total...(not just "modding" or "regulation" etc).

 I have attached photos of the Bradley and Drefahl power supplies (the Bradley photo is from his site, it is a dual supply and appears to have a vertically oriented 3pin regulator chip heat sunk on the left hand side of the unit. The Drefahl I own and it is regulated - both HV and heater- by traditional 3pin chips, no opamp style regulation in either...in my opinion both are good supplies...(I have used the Bradley).

    I don't think that "whats required" should be the ceiling. We as designers of tube microphones owe it to the giants of history to honor their progress and ingenuity.
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R-AP.SCI

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Re: regulated power for tube mics-- impact on sound?
« Reply #27 on: January 21, 2011, 03:52:27 am »

...sorry, here is the Drefahl.
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Gustav

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Re: regulated power for tube mics-- impact on sound?
« Reply #28 on: January 21, 2011, 06:49:21 am »

3 pin regulators have opamps inside.  They have a pass device and an error amp and a voltage reference and maybe some other things like over temp and over current protection

http://en.wikipedia.org/wiki/File:LDO.png
http://en.wikipedia.org/wiki/Voltage_regulator

Gustav
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johnR

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Re: regulated power for tube mics-- impact on sound?
« Reply #29 on: January 21, 2011, 06:58:25 am »

Use of standard voltage regulator ICs doesn't necessarily result in noisy power supplies. They are quite efficient noise generators, as are zener diodes, so adequate filtering is required to attenuate the noise.
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