Best M8080 NOS tube for CJ preamp line stage?

Jeffrey, thanks for the offer. I sent you an email.

no problems really; just waited too long to replace the m8080's and did it with stock dealer tubes. The difference in sound sparked a new level of understanding re. the potential sonic impact of tube rolling. I know I can do better so will give the mullards a shot. do you have a year recommendation?

Dre, the original M8080's were indeed Mullard. The replacements, sent by CJ through one of their respected retail dealers, were not. That being said, the pre-amp has never sounded better. I cannot identify these tubes but they seem to be really good. BUT, if i could find some NOS Mullard or RCA, I would try those as well. Found a few dealers on line that seem to have passed through the audiokarma filter (a bunch of DIY guys mainly), and the prices are a little higher than for the new Genalex 12AX7 tubes, which run roughly 40 bucks each. Check this out and let me know what you think:

https://www.tubeworld.com/index_high.htm

I just bought some old records so I'll check under the hood in the morning.

Dre, Here is how the tube reads, top to bottom:

000-458
CV-4058
KQDD/K
80-45

Dre, just discovered this online:

6C4 tubes are available from Watford Valves of England as the Mullard CV4058 (military number) which is also known as a KQDD/K or M8080. These tubes are the best 6C4 variant that money can buy, and Conrad-Johnson uses them in their new PV-14L audiophile preamp. They told me they have never found a better 6C4 tube. They were made for Britsh military mobile radios and can really take a thrashing, as well as a minimum 10,000 hour useful life.

http://www.rickresource.com/forum/viewtopic.php?f=1&t=13899

Looks like CJ did me right. Wondering what they recommend for the phono stage--but the genalex sound better than those electro-harmonix 12ax7's that were in there initially.

Sometimes I feel like I need two amps--one for acoustic and the other for electronic music. The CJ MF2250 has never sounded better on acoustic folk and jazz, thanks to the tube replacement in the PV-15. And it's not even the "a" version. I'm driving Dali Helicon 400's, and have a Rega DAC with a Cayin CD-t23 transport, and a VPI Scout with an ortofon 2m black. looks like i can wait a while before I upgrade my amp. Still thinking about a butler or a moscode, a VTL or a Cyber or a Rogue, or a Cary or a Cayin. lol. i just don't think a 2500a would be a significant enough upgrade for a larger living space. But right now I'm happy with this set-up in my tiny 12x11 bedroom.

Dre, tube rush was evenly distributed

Update--Just got my CJ MF2250 modded out by Bob and Gary over at Sound Dezign. They replaced the caps, resistors, and power supply for around $360.00, as opposed to the official CJ "A" upgrade which now runs for $650. It will be shipped out today and Bob says it sounds VERY VERY good. will probably get my PV-15 pre modded as well at some point later this year, lol.

Well, first listen, the new parts have not even begun to break in yet, and I have to say the results are outstanding. More detailed midrange, highs are silkier, and the bass is much tighter. Kudos to Bob and Gary. Anyone out there with a CJ MF2250 or 2500 send it to these guys for the upgrade and save some cash.

time for another replacement and this time I will try some cheaper nos RCA tubes just to see how they sound.

Since the last discussion, I sold my CJ mf2250 for a JWN 90w per channel tube amp, upgraded from the rega dac to a Neko, and added a mac mini to my set up.