Avalon 737 Retube

[Dan]

I just retubed one of my 737s. It had the Sovtecs in there originally, but ordered tubes from Avalon, and got Electro Harmonix. They send tubes in a box labeled 1, 2, 3, 4. I know all of them were ECC83's replacing 6922's. I have a second 737 that I compared it to before, and after. It didn't seem to make a huge difference. (The other still has the Sovtecs)
I believe the EQ is solid state, and has nothing to do with the tubes. I think (really not sure) 1 is the mic pre, 2 is the D.I, 3 is the Line in, and 4 is the High Gain mode. If this is incorrect, someone please correct me!

The tubes from Avalon are $80, and pre-tested, and matched.

[woomanmoomin]

Dan, you are probably right about the EQ being solid-state, because the leap from ECC83/12AX7 to E88CC/6922 is actually pretty big!!!! They're not drop-in substitutes for each other!! By the way, I get the impression a lot of EH tubes are actually pretty cr@ppy old Soviet ones, much like the Sovteks. I don't know about their 6922s, although there a lot of rebranded Soviet 6N1Ps around, which are in the same ballpark (6DJ8/ECC88 family). There are probably a lot of rebranded Sylvania 6922s around as well, which probably are not the best. (I like Amperex, but the Siemens valves in this family are also mostly classics.)

Hang on, though... I may be mixing EH up with Groove Tubes as far as some of the details are concerned. Groove Tubes use rebranded GE 6201s (12AT7s) and I dare say they've used a few Sylvanias and Soviet valves too.

Actually some of the Sylvania 12AX7s are supposed to be really good, but as usual, I think, they're the older, slightly more expensive ones. I like Siemens and Mullard ECC83s but it depends on the kind of sound you want, and the equipment.

P.S. I checked out the Avalon. I recommend Amperex 6922s, which I use in my Peluso mic, and you can get them fairly cheaply on eBay, but it may not be worth the bother if they're really not doing that much to the sound. JJ/Tesla probably do a 6922 anyway, and I like the valves of theirs I've tried.

[Gonzalez]

Do you mean I can replace 6992 tubes with 12ax7?

[tradarama]

I purchased them and didn't ever use them. PM me if you'd like to buy them...they are perfect, tested, and from a respected dealer. They aren't cheap but worth it.

[BOWIE]

(Edited in order to be a little more tasteful)
You've allready spent good money on your gear, it's probably worth using quality tubes. All of the newer 6922s soudn pretty bad IMO. The older ones are expensive, but can sound amazing.

[Luisdiaz]

HELP

i am planing to buy an avalon 737 and shure sm7b... its a good idea put both things together or not ....please help

[Nostalgic]

Anything Bowie says about tubes, trust him^.... I need to retube my avalon as well, and will be asking for his advice.

[gyraf]

Detecting a problem here: You can't substitute a 6922 (ECC88) with a 12AX7 (ECC83).

The FF (filament, heater connecting at pins 4+5) is 6.3V for ECC88 and 12.6V for ECC83.

Yes, you can run ECC83 on 6.3V as well, but only by shorting 4+5 and applying voltage between here and pin9 (which is shield on ECC88). Which makes a direct drop-in a no-go.

Surely there is a mess-up somewhere?

Jakob E.

[caryhorner]

O.k. So, I just bought a VT-737sp used for a killer price. My mistake. I should have asked more questions rather than being greedy for a deal. The unit is not quite right and will obviously need a repair. There's a loud, audible buzz/crackle in the signal path and tapping a mic produces a farted out thud rather than an expected fast attack hit. I get the buzz/crackle from both the line and mic inputs, so it's in the circuitry somewhere most likely.

In talking to my friends who are fairly knowledgable about electronics, they say it could be time for a tube replacement. That's about as far as I'll go on my own, knowing I probably couldn't get a schematic for it given everything I've read about the company. My question is, not knowing much about electronics, if I change these tubes out, do they have to be biased or does this unit self-bias? Or does that only apply to power tubes?

[germanduranv]

Dear Friend
The Change of valves (for this type of equipment) not need biassing process. That's for the power valves like the guitar amps.
If you think the problem is in the valves, you need to change the 4.
The process is very simple, open the preamp, take out the valves, and insert the new.
Prices range from 30 dollars to 150 dollars per unit.

Here one list of compatible valves for avalon 737:

6DJ8 Siemens West Germany 1960's
6DJ8 Amperex Bugle Boy Holland "D" getter 1950's
6DJ8 Telefunken West Germany 1960's
6DJ8 Amperex Bugle Boy Holland 1960's
6DJ8 Amperex Holland 1960's and Amperex Holland Globe Logo late 1960's - mid 1970's
6DJ8 Mullard 1960's
6DJ8 Mullard 1960's (either branded Mullard or Philips or Amperex Great Britain)
6DJ8 Sylvania late 1960's - mid 1970's
6DJ8 GE USA 1960's
6922
ECC88
E88CC
CV2492 (CV : Common Valve of Mullard Manufacture)
E88CC/01
CV2493
JAN-6922
CV2492
7308
E188CC
Mullard E188cc/7308

Mullard, Telefunken, Siemens and Amperex Valves are the best
Regards!

[rogerbrain]

Gold Lion Genelx makes a 6922 that is quite good... more than most new tubes but cheaper than most good NOS.. I tried several different 6922's in my AT4060 and the genelex was the only one that was quiter than the factroy selected and seemed to bring the mids up a little which I liked a lot as the 4060 is a little scooped sounding to me.

I also bout a dozen of the gold lion 12ax7's to put in guitar amps and other pres that use that tube ... only one amp I have did not improve with them ... Analog Tubes (on line ) sells them as do several other places

they don't look like other tubes so I think they are a 'special' bigger bottle and very nice looking

[Ike Zimbel]

Originally Posted by caryhorner

O.k. So, I just bought a VT-737sp used for a killer price. My mistake. I should have asked more questions rather than being greedy for a deal. The unit is not quite right and will obviously need a repair. There's a loud, audible buzz/crackle in the signal path and tapping a mic produces a farted out thud rather than an expected fast attack hit. I get the buzz/crackle from both the line and mic inputs, so it's in the circuitry somewhere most likely.

In talking to my friends who are fairly knowledgable about electronics, they say it could be time for a tube replacement. That's about as far as I'll go on my own, knowing I probably couldn't get a schematic for it given everything I've read about the company. My question is, not knowing much about electronics, if I change these tubes out, do they have to be biased or does this unit self-bias? Or does that only apply to power tubes?

Hi Cary,
It could be the tubes, but there can be other issues with these. In particular, you should have a look at the pots from the back (inside the unit) and see if they are white or blue. There were problems with the white ones, so Avalon has been replacing them with the blue, Claristat ones. I have done several of these over the years. I have also had to replace the odd switch.
If you got such a great deal on it, you might want to consider spending some extra to get it up to snuff. Give Avalon a call...
Best,
Ike

[rogerbrain]

Originally Posted by Ike Zimbel

Hi Cary,
It could be the tubes, but there can be other issues with these. In particular, you should have a look at the pots from the back (inside the unit) and see if they are white or blue. There were problems with the white ones, so Avalon has been replacing them with the blue, Claristat ones. I have done several of these over the years. I have also had to replace the odd switch.
If you got such a great deal on it, you might want to consider spending some extra to get it up to snuff. Give Avalon a call...
Best,
Ike

just an fyi on that .. Avalon replaced the pots for free ( I paid shipping ) on a unit that was over 8 years old... they are fine folks afaic