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[Barry Hufker]

Hi Dave,

Thanks for the advice.  I want to clarify - it is not my mic we are discussing.  I'm just enjoying the thread.

I have visited Mr. Dekker's site over the years and nothing has ever changed - not the site, not the gear, not the prices.  And the only thing I'd ever read about him until now is to be a bit wary, as I would of anyone with whom I've not dealt with before or with anyone whose site has not changed every once in a while.

Again, it's not my mic or my desire we are discussing here.

[rodabod]

Barry Hufker wrote on Mon, 14 July 2008 04:57

If they want to get an education, or want to experiment in the hope of creating something better then I encourage them.  "Cost" is in the wallet of the owner.  Education always requires some cost from the student.  Each person must weigh the odds of success, the value of the information learned and the cost of the education/result.

I'm totally with you there, Barry. Whilst I agree that this example experiment may not be feasible with an M49, it would be great if people could try this for themselves. This also avoids the situation we can sometimes get in where one supposedly reputable source reports that something is either good or not good, and evryone else follows like sheep without proving for themselves. There are "facts" about mics I've heard before (especially from the net) which I just don't agree with.

[MagnetoSound]

As Tricatel is already aware, there are several sub-miniature tubes available very cheaply that can be soldered in place of the AC701 if you have the required skills, and wish to try an experiment. Some of them are being used in production models already. There is no reason at all why the 6072 should be considered the only alternative worth trying.

That said, I have to say that I strongly agree with Klaus' sentiments, that such experimentation would be best performed on a much cheaper microphone, and that a valuable M49 would be best left unaltered.

And although, at the end of the day, the owner of the mic has every right to do as he sees fit,  any substitution of, let's face it, a lesser tube, would have to be considered only temporary anyway, until such time as the microphone is put up for sale.

[Klaus Heyne]

rodabod wrote on Mon, 14 July 2008 04:54

Whilst I agree that this example experiment may not be feasible with an M49, it would be great if people could try this for themselves. This also avoids the situation we can sometimes get in where one supposedly reputable source reports that something is either good or not good, and evryone else follows like sheep without proving for themselves. There are "facts" about mics I've heard before (especially from the net) which I just don't agree with.

You already admit that the installation of a 6072 in an M49 mic is not feasible. I was specifically asked about the sound differences between AC701 and 6072 tubes. Then the practicality of such an M49 tube conversion was discussed.

I would not be responsible as forum host and "reputable source" if I would let this thread meander into a territory where modifications are encouraged that are clearly foolish and destructive to the functionality and value of a $8000 mic. So, why, after all this information has been aired, do you still think it would be "great if people would try this for themselves"?

You will have a hard time finding examples where I discourage experimentation (exception: capsule cleaning, and for good reasons) and I will be the first to chime in and report everything I have learned and know about microphones. If my experience has been that the value of a vintage mic is affected negatively through certain manipulations, or that modifications are technically impractical, I will continue saying so, with a loud and clear voice.

[J.J. Blair]

FYI, I'm not sure how up to date that bavodekker website is.  I think it has been static for a couple years.  I wouldn't trust those prices as current.

I recently paid $500 each for some AC701s, and I know of a terrific tube dealer selling them for $600.  And the problem is that even though both dealers have all the testing equipment for every other tube, they can;t test the AC701, as neither of them have the correct jig.  I don't know how many people really do.  Maybe Klaus can comment on that.  

[Klaus Heyne]

Measuring noise, whether steady-state or sporadic, in tubes to be placed in super-high input impedance circuits is not possible with conventional testers. Those that are designed to work in that application cost several thousand dollars, even used. And even then, certain types of noise are not captured, accounting for quite a high percentage of returns from Neumann back to Telefunken during the period AC 701s were manufactured.

That's why I never bothered to invest in one of those testers, but still use the good old ear method of testing: wire it up, set the correct voltages, plug in, let run for seven days, and be satisfied that 90% of all tubes that are still quiet after withstanding that type of testing for a week are guaranteed to stay quiet for at least a year.

[Barry Hufker]

"If my experience has been that the value of a vintage mic is affected negatively through certain manipulations, or that modifications are technically impractical, I will continue saying so, with a loud and clear voice."

But you miss the point.  YOU experimented. How did you come to your knowledge?  You EXPERIMENTED.

Neither Roddy nor I are advocating recklessness.  But for anyone who wants to take the chance and can afford the consequences - even just as an experiment - then I encourage them to do it if they think the odds of success are good and there something is to be gained.

I can't tell you how many times I've taken an chance (often an expensive chance) on something and have had it turn out well.  While I've had a failure or two I learned from those but the positive results were such that I continue to take those chances when I think there is a good chance of success.

As forum moderator you have a responsibility to the reader that I don't.  So let's accept both points of view.  I am advocating a responsible position you don't agree with and let's let it go at that.

[Klaus Heyne]

Barry, the two positions you outline are not contradictory, but complementary:

I am for independent experimentation, but all information on the subject already generated from prior experimentation by fellow experimenters should been taken into account. Otherwise we would still try to cure infections with exorcism, and try to install 6072s in M49!

The internet makes it extremely easy now to research what has worked for others and what has not, and why.

[Barry Hufker]

Klaus,

I agree.  Both positions are complementary - equally needed and equally valid.  I appreciate your statement of that view.

"The internet makes it extremely easy now to research what has worked for others and what has not, and why."

This statement shows there is a firm foundation for future experiments!  Knowing what came before allows a person to see where the pitfalls are and makes obvious the absence of knowledge in certain areas.

In saying that please note I am not referring specifically to putting a 6072 in an M49.  I'm just encouraging a general growth of knowledge.

Thanks!

[rodabod]

Klaus Heyne wrote on Mon, 14 July 2008 17:44

So, why, after all this information has been aired, do you still think it would be "great if people would try this for themselves"?

"This" being experimentation in general. Yes, I did say that in the case of the M49 it may not be feasible. And if it did fit, then I don't see any reason in not experimenting to try other substitutes; this may apply to other microphones.

[seedyunderbelly.com]

This is silly.

The cost of the mod and the devaluation to the BELOVED M49 shows this as a fool's errand.

If you cannot afford 2 AC701's you can not afford an M49 (buy them now, before they get cheaper!)  I do not have a Ferrari for example.

$, heat, space, resale...

Get a K47 mount and rebuild an Apex if you really must follow folly.

Bravo Klaus for calling it.
j

[Barry Hufker]

Rebuilding another microphone is not the same as experimenting with an M49.  I'm not saying "do it" but I don't get what all the fuss is  about.  Some of us might want to.  Maybe one of us will.  Just because it isn't something you want to do doesn't make it foolish.  All things are relative.  So if you don't want to then don't but lighten up otherwise.

EDIT: What is ironic of course is that if someone does experiment with an M49 and does indeed come up with something outstanding everyone will want to know what was done, how it was done and can a picture be posted to see how it was done.  Then it won't be foolish anymore.  Of course no one was willing to try it but the person who did it.  But everyone will certainly want to benefit from that person's effort.  Likewise, no one will want to help cover the cost of the experiment.

That by the way is true of any successful experimenting adventure.

[seedyunderbelly.com]

No, it will still be foolish after someone tries it.  

[seedyunderbelly.com]

Come to think of it I have some K47 capsules on some 6072 amps (with a clean tranny.)

I know  the transformer is different... It sounds worse than an M49.
K47, K67, and CK12 capsules were engineered well to work with their respective systems.

If it is not  a notable difference between 6072 or AC701 in a 251, what is the advantage sought?  Purely a less expensive tube?  Which would devalue the mic more than the cost of a lifetime supply of the tubes (which incidentally would likely rise in value)?

It does not fit, and would not sound better and may not even work, and also is more costly.

No malice intended, but rarely is the term "Fool's errand" more appropriate.
There is no upside to this.

j

[rodabod]

seedyunderbelly.com wrote on Mon, 14 July 2008 22:48

No, it will still be foolish after someone tries it.

I guess it depends on how you appreciate mics. I think I just treat them as tools for recording/broadcasting. I don't get attached to their history.

I wouldn't probably ever buy an M49 due to their price, but if I were to have one with a failed AC701, I might try a "compatible" sub-miniature. It would not necessarily sound worse. It could potentially sound better. Even if the substitution did not sound as good in the end and I reverted to the AC701, I would still have learned something.