I few months ago I won the auction for JAN 5703 tube and the seller send me the instructions how this tube can be interchangable with AC701. What are your opinions on that people except that this tube runs on 6.3V ? Does someone try it in microphone project and how does it compare with 5840 and of course why is 5840 wired as triode and no one using 5703 as natural triode ?
Thanx and best regards.
I remember seeing somewhere that Tracy Korby used it as a replacement for the AC701 for whatever that's worth.....
PS...could you possibly sent me the info at ciminosound(at)yahoo.com???? pleease
Not that I want to pollute your conversation with talk of hi-fi...
The follow-up product to Musical Fidelity's "Nu-Vista" (sic) range is the "Tri-Vista" which, you guessed it, has 5703 triodes buffered by transistors. Apparently they bought several thousand 5703 as they did with the 6CW4 (Nuvistor used in the Ampex mr70 btw), with a spare pair for every customer.
That's my piece of trivia for the day.
"actually, I'm not a trained technician at all, I used to play piano in a brothel but business was bad, so..."
I saw this amp yesterday. Seller for which I bought the tubes claims that this tube in someway outperform AC701. I am begginner in tubes so maybe from you guys will deny that ...
From reading what I can find on the ac701. It appears this tube was made for microphone use. The grid leakage current is very low. The grid exits the other side of the tube. It has double mica washers for lower grid current. A certain oxide on the cathode etc. Problem for me the good info is in german.
This would be a good tube to have made again. It might be the best tube for tube microphones ever made.
FWIW, while the 6CW4 Nuvistors were used in the mike preamp section of the MR70, the record and repro sections did not use them. Those sections used 7897 triode and 7587 pentode nuvistors.the 6CW4 (Nuvistor used in the Ampex mr70 btw)
FWIW, while the 6CW4 Nuvistors were used in the mike preamp section of the MR70, the record and repro sections did not use them. Those sections used 7897 triode and 7587 pentode nuvistors.Originally posted by Fred Forssell:
</font><blockquote>quote:</font><hr /> the 6CW4 (Nuvistor used in the Ampex mr70 btw)
Fred Forssell </font>[/QUOTE]Thanks for that info Fred. I have a mr70 schem, should've checked it before posting here!
Out of interest, have you used the mr70? Does it live up to the reputation?
Back in the mid to late 1970's we had several MR70 machines in a couple studios in which I worked when I wasn't on the road. We had a couple of MR70 2-tracks, a 1/2" 4 track and a rare(even for MR70s) 1" 8 track. (An aside, someone told me at the time that the 8-track MR70s were built for the United Nations to record multiple translations simultaneously, and that there were something like 30 of the machine built for the UN. I don't know if that is true or not, but it sounded reasonable at the time.)Out of interest, have you used the mr70? Does it live up to the reputation?
Sonically, the machines were really, really good. We never used the mic preamps and truthfully, I don't even remember if any of those machines had mic preamps installed.
When properly aligned and maintained, the transports were really cool to use as well. But the transports needed lots of continuous tweaking to keep the running well, and it was kind of a pain. This was back in the days when studios had full time people that did nothing but maintainance and tech work (our studio had 3 full time techs), so it was too big of a deal to keep the MR70s, the Studers and the other Ampex machines running well.
But the sound of the MR70 was really great. I don't know what ever happened to those machine after I moved on.