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R/E/P => Klaus Heyne's Mic Lab => Topic started by: Marnay on March 29, 2014, 03:34:06 PM

Title: U47 whith AC 701 Telefunken
Post by: Marnay on March 29, 2014, 03:34:06 PM: Hello to all
Here is an alternative to continue using a Neuman U47 with Ac701 Telefunken, I modified my U47 with the attached diagram and here's a demo record voice directed with this microphone:https://soundcloud.com/magazine-records-1/mr154_13-mp3, that is no longer a U47 of origin! but remains in the Neuman (Mix of a M249b and a U47) philosophy.

PS I did not use the capacitor C4
Title: Re: U47 whith AC 701 Telefunken
Post by: klaus on March 29, 2014, 04:15:19 PM: There is a fairly small difference in price between the VF14 and an AC701- about $600-$800. You also can no longer use the original U47 power supply and cable.

So, I am curious to understand what your motivation to modify your U47 was?
Title: Re: U47 whith AC 701 Telefunken
Post by: Marnay on March 29, 2014, 05:18:17 PM: in fact I have a stock of 20 tubes AC701 and I have an another U47 of origin, I was curious to hear the sound with this tube that I appreciate in my Schoeps and M367 Neuman
Title: Re: U47 whith AC 701 Telefunken
Post by: klaus on March 29, 2014, 11:56:41 PM: So, how do you like it, compared to a stock U67/M367?
Title: Re: U47 whith AC 701 Telefunken
Post by: Marnay on March 30, 2014, 05:18:23 AM: This is quite different from a M367 high medium and less front and low medium to a different color. It does not resemble the U47 that I owned.
I do not know or the located (I do not know the M249b) but it has become one of my microphones preferred voice with the U47/U47 Fet/U87/U67et the M367 each with a very different character. (Sorry for my English)
Title: Re: U47 whith AC 701 Telefunken
Post by: hasbeen on March 31, 2014, 11:42:08 AM: Quote from: klaus on March 29, 2014, 04:15:19 PM
There is a fairly small difference in price between the VF14 and an AC701- about $600-$800.

Do you know anyone selling VF14 for this price? Thanks
Title: Re: U47 whith AC 701 Telefunken
Post by: klaus on March 31, 2014, 12:54:23 PM: Current AC 701 prices hover around $600. The last two eBay sales (completed auctions) for VF14 were $745 and €760, respectively.

That is relatively cheap. The average price I have seen over the last three years of VF14 that actually sold (not asking prices, mind you!) was around $1200- $1400, which constitutes the price difference to an AC701 I was referring to in my post.
Title: Re: U47 whith AC 701 Telefunken
Post by: hasbeen on April 07, 2014, 02:15:29 PM: I just watched a VF14M rebooted by Klaus sell for $2800.

What is the average charge for this service? Thanks
Title: Re: U47 whith AC 701 Telefunken
Post by: klaus on April 07, 2014, 02:58:48 PM: First, the price this tube achieved strikes me as insane.

Second, I am pretty vigilant about keeping even the slightest appearance of mercenary interests away from this forum.

Contact me privately, please.
Thanks,
KH
Title: Re: U47 whith AC 701 Telefunken
Post by: hasbeen on April 07, 2014, 08:08:23 PM: Sorry. Did not mean to offend and should have clarified. I was pondering the ballpark price that the people who do this VF14 'reburn in process' charge. Not specifically you. I know others do it too.

If I need it done someday though, you would be the first I would contact.
Title: Re: U47 whith AC 701 Telefunken
Post by: klaus on April 08, 2014, 12:01:07 AM: The issue is pretty complex: you can regenerate several ways. In some cases, like the VF14, you may need to complement one approach with another, otherwise the remedy may not last.
But, whomever you hire, make sure that you get a decent warranty with the service.
Title: Re: U47 whith AC 701 Telefunken
Post by: hasbeen on May 07, 2014, 04:51:30 PM: I just watched another VF14M sell for $5600 on ebay! This is insane!!

I should mention that the bidder who won appears to have zero feedback. But still he was bidding against another bidder. I am just searching for clarity in this insane transaction!

The specs he mentioned were:

TUBES TESTED 12 MA NOISE TEST 20-800HZ 0 DB 1000-20.000 HZ +- DB FIRST TEST BY TONE GENERATOR LEADER LAG-26 AND SCOOP PM 3262.ALSO TEST IN NEUMANN U47.

I am not schooled in this jargon, sorry.

Are these respectable stats or just gibberish?
Title: Re: U47 whith AC 701 Telefunken
Post by: klaus on May 08, 2014, 11:22:21 AM: I cannot bring clarity to this auction's process or the insane price this tube achieved.

We are also not privy to any private communication between seller and the final two bidders who lifted the tube's price out of reasonable territory into the atmosphere. But the fact that both bidders have an extremely low bidding history (1 and 7) makes me wonder what was really going on here. It may be as innocent as a money laundering operation between drug dealers.

And: no, the "specs" are gibberish, and cannot help determine the quality of this tube in its intended application.
Title: Re: U47 whith AC 701 Telefunken
Post by: hasbeen on May 20, 2014, 11:34:53 PM: Well it seems the tube is up for auction again so there were obviously nefarious motives involved in the last go around.
Title: Re: U47 whith AC 701 Telefunken
Post by: klaus on May 21, 2014, 12:27:04 AM: Wouldn't the world be a paradise without all these guys (and it's mostly guys) with their nefarious motives?
Title: Re: U47 whith AC 701 Telefunken
Post by: Piedpiper on May 21, 2014, 03:20:24 PM: but then we wouldn't be able to use such great phrases as "nefarious motives"...