7199 substitution in Ampegs

[Snapcase]

I read somewhere there are several drop-in mods for Dynaco 70 amp drivers allowing them using more common and easy to find tubes than the scarce 7199. Would those work on Ampeg B25 or Gemini amps? Any idea about were to find those schems? Are this advisable or is Sovtek 7199 good enough and doesn't worth the effort such mod?



Thanks.

[Zoe_N_Iain]

I've seen the Dynaco 'sub' list, too. Don't see a problem with doing the same in an Ampeg or whatever.

FWIW, though, the Sovtek 7199 sounds every bit as good as NOS to my ears, though I only tend to use them as an input stage. There might be a noticeable difference if used midway through the amp, I suppose, but up front they respond exactly the same to a boost or distortion pedal as a NOS one does. Worth trying one, given the reasonable price.

[Snapcase]

Thanks.

Well, the thing is the reverse. I used Sovtek 7199 in driver possition on Ampegs. But I only had the chance with an old and wore Sylvania. I cannot tell the real difference because that amp was full of GEs and Sylvanias. It sounded superb, but don't know how much affected that 7199 to the whole thing. This is why I'm asking.

[TD_Madden]

those Russian 7199s hum like crazy in my Gibsons.

[Amp Kat]

Before the 7199 was a 6AN8 in the Stereo 70 and they can be used with very minor changes. Many opted for the ECF-80 with some surgery but is much cheaper and sounds as good. The Sovtek is a hit or miss tube as they are not selected and you could get a real hummer or you could get a decent one which is why there are so many sparatic reviews of them. IMO the Sylvania and any NOS are the best sounding as with any NOS tube but the price almost triples and that's the reason why is because they are that much better. Take a shot on the Sovtek if you may but don't be surpised if you get a hummer.

[Snapcase]

This might explain why my B25s keep humming a bit after a full recap job.

Any idea about 7199 substitution for Ampegs?

BTW, What Gibson models used 7199?

[Snapcase]

Well, bad news. Sov 7199 has been discontinued. So alternative tubes are starting to be a real need.

http://store.triodestore.com/7199sov.html

What are those minor changes for 6AN8 usage?

[TD_Madden]

tweed Falcon (GA-19RVT)......brown-version went to 6AN8.

[Snapcase]

This might be a possibility

http://home.alphalink.com.au/~cambie/6AN8amp/6AN8_t.htm

[TD_Madden]

Think the Groove Tube Tube Amps Vol 4 has a section describing this change as well as a 6EU7 to 12AX7 rewire.

[Amp Kat]

Originally Posted by TD_Madden

tweed Falcon (GA-19RVT)......brown-version went to 6AN8.

Those are cool amps TD and sound great with NOS tubes. That's where I found those Black Lafayette tubes I posted about. I did a falcon and have a discovery in right now that needs some serious work but they were excellent amps ! Great tone at low volumes.

Snapcase I'm sure you can find at least 10 Sovtek 7199's right now pretty easily. At least I bought some from CE a couple of weeks ago. How many do you need after-all they last a pretty long time so 5 will most likely outlast you !. You'll have to rewire the pins on the 6AN8 as it's different than the 7199 and may have to make a resistor change. Go to the Sunn Forum and see if their are some schematics for any of the Sunns with the 6AN8 . The S100 I believe is a 6AN8 based PI and it will show you one wired up.

[TD_Madden]

isn't the 6AN8 a "miniature" tube....needs a re-socket, I think.

[stokes]

I tried the Russian 7199's in a couple of my Ampegs,and I agree they sounded okay,but they didnt last very long,so I ended up hunting down some NOS

[TD_Madden]

correction....the later Falcons used a 6C4 (not 6AN8), as I have been informed...(of course, I COULD have just looked!)

Sorry about MY confusion.

[kurisurokku]

Resurrecting this thread, in case anyone searches for it. www.thetubestore.com has good instructions on using a 6U8A tube instead of a 7199. You just have to re-wire the pins, no resistors needed. Here's the link:

http://lib.store.yahoo.net/lib/thetu.../6U8A-7199.pdf

I haven't done this myself so I don't know if it sounds good or not, but wow those 6U8A tubes are waaaay cheaper than 7199's ;-).

[Zoe_N_Iain]

Yup. Sound pretty much the same. Bit more top end chime, if anything.

The pentode usually has very slightly lower gain than a 7199, given the same B+ and resistance values, and the triode has roughly the gain of a 12AV7 versus ~12AU7/12AY7 for the 7199's (depends on the type how high mu the triode is).

In our experience, the triode is slightly better at rounding the rough edges off the signal, if used as a cathode follower after a gain stage, than the one in a 7199. But that's generally an improvement in tone, rather than a bad thing.

And they're cheap and easy to get, so...

[jrfrond]

The most widely-accepted sub is the 6U8A. I purchased some of these on my last tube order, just to have for whenever we blow through our 7199's. Fortunately, the 7199 has never been a big mover for us. Of course, hindsight is 20/20, and I would have hoarded some 7199's when I had the chance, like I did with 6BK11's.

Unfortunately for us techs, the fine engineers at Magnavox/Ampeg liked to use these oddball TV tubes in their guitar amp designs. I don't recall seeing any other amps other than Ampeg using the 7199, but I could be having a pre-senior moment.

[telemoxy]

Originally Posted by TD_Madden

Think the Groove Tube Tube Amps Vol 4 has a section describing this change as well as a 6EU7 to 12AX7 rewire.

The 7199 to 6U8A instructions are on page 764. Couldn't find a reference to 6EU7 to 12AX7 but you can still get 6EU7s.

[Albert Kreuzer]

Originally Posted by jrfrond

I don't recall seeing any other amps other than Ampeg using the 7199, but I could be having a pre-senior moment.

Sunn?

Cheers,
Albert

[jrfrond]

Thanks! Forgot about that one!

[drewl]

Found this thread while researching a Sunn Solarus I'm fixing.
It's shame the damn 7199 has some hum, otherwise this would be a nice quiet amp.
It seems they also used the 6AN8 in some and the 7199 in others.

[soundmasterg]

Conrad Sundholm has told me in the past that if he knew what he knows today, he would never have used the 7199 or 6AN8 for his designs back then. They aren't very good sounding tubes as compared to some others out there. I'd have at it with swapping to something else. The Stereo 70 mods are all over the map, but I've heard of one using an EF86 and 12AU7 triode stage setup as a cathode follower for each channel that is supposed to perform and sound quite good. YMMV.

Greg

[hasserl]

Originally Posted by jrfrond

I don't recall seeing any other amps other than Ampeg using the 7199, but I could be having a pre-senior moment.

Originally Posted by Albert Kreuzer

Sunn?

Cheers,
Albert

I've got an Alamo Paragon Bass amp here that uses a 7199, a very nice sounding amp for guitar, very nice.

[Enzo]

The SUn amps of that era used the 7199 and the 6AN8. They also used EL34s and KT88 power tubes. The power tubes made the choice of which PI tube was used.

[drewl]

Well that explains it, it seems there's a couple versions of the Solarus, one with 7199 one with 6an8.
Another difference is the trem photocell is on V1a or V1b.

[TD_Madden]

Gibsons.