school me on power supplies - U67, U47, M49

[Andrew Kinsey]

Original PSU will allways be something that increases the resale value of a Vintage Mic.

In the studio however the PSU can be a bottleneck to the performance of the mic. Personally i would suggest checking out the Grimm Audio MP1 if you are looking for a replacement PSU for a tube mic, they also make a version of their PSU specifically for U47's.

Peluso also make PSU's for their respective vintage clones, but not all of these would neccesarily be compatible with the original's.

[Emwolb]

Originally Posted by Andrew Kinsey

Original PSU will allways be something that increases the value of a Vintage Mic.

In the studio however the PSU can be a bottleneck to the performance of the mic. Personally i would suggest checking out the Grimm Audio MP1 if you are looking for a replacement PSU for a tube mic, they also make a version of their PSU specifically for U47's.

Peluso also make PSU's for their respective vintage clones, but not all of these would neccesarily be compatible with the original's.

Thanks Andrew.

I figured as much on the value side. How much do you think it affects price?

Just FYI- Im not looking for a power supply, Just trying to find out if I should care when buying. the brands I listed are just some of the ones Ive seen already.

[Andrew Kinsey]

Originally Posted by Emwolb

Thanks Andrew.

I figured as much on the value side. How much do you think it affects price?

Just FYI- Im not looking for a power supply, Just trying to find out if I should care when buying. the brands I listed are just some of the ones Ive seen already.

Pricing would depend on what PSU the microphone was using, if its an original PSU has it been recapped and serviced and by whom? there are alot of variables and the danger is that if the PSU is not performing as it should it can reduce the lifespan of the tubes.

[Emwolb]

Originally Posted by Andrew Kinsey

Pricing would depend on what PSU the microphone was using, if its an original PSU has it been recapped and serviced and by whom? there are alot of variables and the danger is that if the PSU is not performing as it should it can reduce the lifespan of the tubes.

I think you misunderstand. I understand how tube mics work and how power supplies need to be working as spec.

This is all based off the assumption the power supply works as it should. I understand variables- but they don't help me with generalized value.

Im trying to assess, in an idealized situation- assuming the power supplies work 100% as they should, new or old, how much do they affect value and sonics.

Is there a benefit, OTHER than value, to an original supply as far as sound/function go.

[skybluerental]

you will be hard pressed to find anyone with much experience as an electronics engineer or an audio engineer who will argue that there is any sonic benefit to a new vs old power supply, assuming both are functioning correctly.

as for value, the original PS will increase the value.
this is more about nostalgia and vanity than performance.

[Emwolb]

Originally Posted by skybluerental

you will be hard pressed to find anyone with much experience as an electronics engineer or an audio engineer who will argue that there is any sonic benefit to a new vs old power supply, assuming both are functioning correctly.

as for value, the original PS will increase the value.
this is more about nostalgia and vanity than performance.

Awesome, thanks!

[unit7]

Originally Posted by skybluerental

you will be hard pressed to find anyone with much experience as an electronics engineer or an audio engineer who will argue that there is any sonic benefit to a new vs old power supply, assuming both are functioning correctly.

Exactly my experience too, having discussed this with Andras Grosser who BTW makes fine PSUs for the mics you mention.

A little OT, but here's an extra tip regarding 2 ch PSU's. Andreas instructed me on how to measure the voltage feeding the mic on one of my Gefell 582 pairs. I had a fairly well known brand 2 ch PSU that I got with these mics. This PSU worked fine with only one mic (120V ±2V), but as soon as both channels was connected to the mics, the voltage fell under spec (112 & 109V).

[Vintageidiot]

AMI Tabfunkenwerks also makes power supplies for U47, U49, km series etc.

[Emwolb]

Originally Posted by unit7

Exactly my experience too, having discussed this with Andras Grosser who BTW makes fine PSUs for the mics you mention.

A little OT, but here's an extra tip regarding 2 ch PSU's. Andreas instructed me on how to measure the voltage feeding the mic on one of my Gefell 582 pairs. I had a fairly well known brand 2 ch PSU that I got with these mics. This PSU worked fine with only one mic (120V ±2V), but as soon as both channels was connected to the mics, the voltage fell under spec (112 & 109V).

Thanks- exactly the type of info Im looking for!

[Marcocet]

Originally Posted by skybluerental

you will be hard pressed to find anyone with much experience as an electronics engineer or an audio engineer who will argue that there is any sonic benefit to a new vs old power supply, assuming both are functioning correctly.

I don't think that's strictly true, due to the fact that most modern supplies have regulated heater voltages and vintage ones were consistently unregulated. Personally I use both styles interchangeably, but I've heard people argue that they can hear the difference. I've yet to bother putting the two styles up against each other, or experimenting enough while building my own, to have an opinion on the issue. I have vintage mics using Hamptone, Bill Bradley, Korby, AMI, off-brand, and original power supplies and have zero complaints about any of them when they're functioning properly.

[Andrew Kinsey]

Originally Posted by Emwolb

Im trying to assess, in an idealized situation- assuming the power supplies work 100% as they should, new or old, how much do they affect value and sonics.

Is there a benefit, OTHER than value, to an original supply as far as sound/function go.

The original supply will increase the resale value.

The design of the PSU does affect the sound of the mic, so in essence it all depends on which PSU your comparing this vintage PSU with.

In the case of a modern day clone, there should be no real difference provided that both are working properly.

There are also other PSU's that one can use which are designed to improve the performance of old tube mics.. like the Grimm MP1 for example.

It is also quite possible that some of these boutique manufacturers are using more modern designs rather than cloning an old vintage PSU design.

So it does all depend on what your comparing the Vintage PSU with.

[R-AP.SCI]

Good day all,

It is quite true that power supplies do make a measurable difference (yes when both are functioning correctly).

For example, the U47 has no B+ regulation and once connected to AC of significant variation (I've seen +/- 5V and more, but then again I work all over NY) your signal to noise can vary somewhat as the capsule polarization voltage is derived via a resistor divider from this voltage, thus with lowered voltage capsule sensitivity drops. Not to mention that the heater/filament is also powered from this voltage. One should also consider that these (power supplies) were designed within tolerances of acceptable ripple, noise, etc and thus will function just fine within these tolerances, but this does not preclude that it could not be "better". Nor does it preclude that the measurable difference will be strictly academic. For instance (C1 on the U47 not only forms AC to ground but is also necessary to filter the noise/hum that is left over from the properly functioning power supply) and this noise/hum is not insignificant/irrelevant (I.E. 120dB down or such)....the limit (of acceptability) for some is different than for others, however as far as I am concerned if these things aren't at LEAST 80dB down (in which they aren't in some cases) it can, and in many cases does, make an audible difference (the degree of audibility I leave open ended as this depends on many other interdependent factors).

Some more modern microphones use switchmode supplies with consistently measurable switching crud everywhere, consistent from unit to unit.

I guess the point is that simply because a microphones power supply is functioning within the specifications it was designed for (thus properly functioning and non damaged) does not truly mean that it will not have a measured or sonic impact on the microphone, for better or worse.

Power supplies are of utmost importance to me as a designer/manufacturer and I feel that this is an area in many microphones that could be improved upon. There are a variety of technologies with which to achieve a given goal....and all have a variety of advantages and drawbacks. It also should be of note that the circuit it is mated to will have an affect on sonics as differing circuit topologies have differing abilities to reject power supply imperfections (if any). An original supply, depending upon the microphone, is in many cases (as far as I have observed) an exercise in basic filtering and (sometimes) regulatory techniques designed to meet a price point.

Regarding the supplies of the classics, they are good indeed and more than sufficient, however they are not a metal film clad fist aimed at the jaw of imperfection. They too had cost considerations and a line they had to draw in the sand for acceptable performance with the available technology. At the time it most definitely was, for the most part, greatness...but those were different times.

I believe that Jim from JJaudio actually posted some of his measurements regarding noise measured from a properly function supply, pre & post modification on this site somewhere.

The perceived value of a "better" power supply is in the end left up to the user. However it is a fact that power supplies in microphones do have measurable differences and those differences CAN contribute the sonics of the microphone in an audibly beneficial or degrading fashion.

I hope this helps in some fashion.

[Emwolb]

Great posts everyone and a big help!

Thanks!