Finally got my 1972 Ampeg V4 serviced. Previously, it had all original tubes and JJ 7027 reissues in the power section, which I beat the hell out of over the past three years of consistent gigging and recording. After a lot of work (along with some minor bias modifications by my tech), I am pretty convinced that my Ampeg V4 is the best sounding Ampeg V4 I’ve heard for both guitar and bass applications.
This is what I retubed it with:
- V1: 12AX7 | Input 1 (JJ)
- V2: 12AX7 | Input 2 (Mullard reissue)
- V201: 6K11 | Midrange (NOS)
- V202: 6CG7 | Reverb Send (NOS)
- V203: 12AX7 | Reverb Return (Mullard reissue)
- V3: 12DW7 | Cathode Follower (JJ)
- V4: 12AU7 | Phase Inverter (NOS)
- V6 - V9: 7027A | Power (Tung Sol 7581)
For V1: My tech recommended the JJ because it had much lower noise than the Mullard reissue, and I agree. Quieter tube, doesn’t break up as fast, but very tight and articulate. For V2: I still wanted to use the Mullard reissue tubes I got so I decided to keep one in V2. MUCH louder than the JJ and very harmonically rich especially in the midrange / lower end, but significantly more noisy than the JJ. In the power section, I decided to go with the new production Tung Sol 7581, a 6L6GC variant, as I didn’t really want to run my amp with 6550 tubes and likewise didn’t want to use junk/potentially unreliable “reissue” 7027A’s or shell out way too much money for Winged C 6L6GC’s. My tech extensively tested the 7581 tubes and said they performed just as well as they should if not better than any other modern production power tube in this particular amplifier. (Shout out to Tom at Aztech Electronics in Watertown, MA for being the best amp tech I’ve worked with).
The amp sounds better than it ever did, and it’s also extremely nice to have a fully-functioning amp yet again. Just wanted to share my experience on here for others to note if looking for resources!
Also for reference, the cab is an early 1970s Orange/Matamp 4x12, chopped up and beat to hell. I paid $50 for it a few years ago from a warehouse liquidation and recently replaced the speakers (they were non-original anyway) with two Celestion G12T-75’s and two G12K-85’s (same as G12K-100), all from the 1980’s and made in the UK.
Submitted by zachxweeks. Thanks Zach! This reminds me that I need a new 6K11.
I just put the Tung Sol 7581’s in my ‘72 V4 too and they’re amazing. JJ in general however are really unreliable. Mullard just came out with a low noise version of their 12AX7 I’ll be grabbing.