Much like metals and commodities during times of fiat value nose-dives:
Old NOS vacuum tubes will only go UP in price from here.
They are not making any more and the ones they have made will be slowly
consumed and used, therefore making current stocks rise in price as supplies dwindle.
i dont know where you guys are buying your tubes. but i bought a matched pair for 400 euro two days ago. tested and NOS. you might want to ask some nice german repair guys and not the crazy vintage ripp off tube dealers in the states....
Just buy in DE for $100. I know a place that has upwards of 500 NOS AC701K.
No big deal.
no...its not that cheap im afraid. most of them are not usable for mics. so you need to get them tested by someone who knows about the right SN ratios. obviously they get a little more expensive once tested and selected....but the 2 grand figure is way off. around 300 euro is a normal price right now...
yup. Although $700 may be typical, they seem to be available for significantly less, although QC is always a question...
True. There are two tiers: a) acceptable quality for recording, b) not acceptable quality for recording. There seems to be no shortage of 701s which were originally discarded, but are now being sold as "b" and they might not tell you that up front.
Thanks but because there are so many of these around the world, and because they seem to last a long time, and because mine are showing no signs of wear (knock on wood) I've decided to pass on the purchase. But if one starts to fade I'll again start looking.
Make certain the AC701 heater is set for 3.8 to 3.9 volts (dc) at the mic. Test (by substitution) resistors, etc. before blaming the AC701. The AC701 is too expensive to blame before checking the other components first.
The only other alternative is to NEATLY and REVERSIBLY mod the mic for a 7586 nuvistor or a 5703 submini. You then have to mark power supplies so they never get interchanged with AC701 mics.
Which is exactly why I bought a U67 (with ubiquitous EF86 tube) and not an M269. A couple AC701 tubes & you've bought a new microphone! A mildly out of spec 50 yr old power supply voltage & you shorten the life of those exorbitant tubes. No thanks. I'll just add some high-frequency air-band back to my U67 with an EQ.
If you have a mic with a AC701, make sure you have the heater voltage adjusted for 3.9 volts AT THE MIC. This means working around HT so be careful. Use small clip leads on the probes to this. Use a good quality digital DC voltmeter for this adjustment! Heater voltage is critical for long life. Always check other components for defects before blaming the AC701.
If you mod a mic to use a 7586 or 5840 or 5703, the heater voltage needs to be raised to 5.6 volts. The NKM or NSM supplies can be modified to do this, and are also easily cloned. I like the way the HT is regulated right off the rectifier with the gas regulator tube (150B2 or rewired to 0A2).. Mark modified supplies so they are never used with a AC701 mic.
Also suggest emailing or contacting JJ Electronic to make a run of AC701's. Good supplies of AC701's may drive the price down to acceptable values...JJ makes a nice EF806..if you order one for a U67, make sure you tell Eurotubes or JJ Electronic it will be used in a mic so you get a quiet one....
yes its really bad with ac701s... hardly any supply. and the little stock that is still around is mostly tubes rejected by neumann and hardly usable. argh....
There are close to 10,000 NOS AC701 tube out there. Trouble is they are owned by 2 gentlemen in Europe. They hold onto them to keep the price up there. (roughly 500.00 to 750.00 per tube).
I know the gentleman who bought the original equipment to make the AC701 tubes and had it shipped over from Europe when he moved to US, but he is not "there" yet on setting it up or re-manufacturing these tubes... and he may never be as he'd have to remake more than just the AC701 to make it worth his while and the mans time is very limited as it is.
You might want to read the entire thread which elaborates on actual prices (not the package deal which started the thread), TRUE availability, likelihood that the tubes are garbage or even fake, etc.
To put this thread to rest, I had my KM54 fitted with a NOS 701 several months ago and the price was in the $500-700 ballpark. Not thousands. Not $100 (it's a legitimate 701, in proper working condition, suitable for a quiet microphone).
I hope those two Europeans who are holding ~1,000 AC701s in order to force the prices up lose theirs shirts in the process. I've watched it happen to so many gear collectors who artificially jacked up vintage prices only to have a 'valid' reissue, or some other way to obtain the product at low prices, slice their inflated profits down to nothing.
Now if only we could find a few "gentlemen" hoarding VF14s. That would be something.