Tubes in your system?

[jon_s]

FWIW, here is my rating from worst to best:

Mullard: they do a lot right: very nice midrange, bass is good but, the high end is rolled off some. A little too much if you ask me.

Cleartops: very nice and a really extended high end. Really noticable when compared to the Mullards. Good bass and a nice midrange. I thought this would be the winner until I heard...

Amperex: This tubes gives you the best of everything. The high end is really sweet and makes the Cleartops sound bright in comparison. Bass and midrange are excellent too. This tube just seems to get it right.

I agree very much, and these seem to apply in a number of circuits I've tried. This includes my Foreplay, a Consonance Basie, and a Scott 350C (instead of 12AT7's). I keep an Amperex in the 350C, a pair of RCA cleartops in the Foreplay (too bright in the Basie), and a pair of Sylvania 6189 mil-spec blackplates in the Basie.

 

[ldatlof]

The 12AU7 GE's are outstanding IMHO. The ones I have are made in Canada and have MT vertically next to the round GE trademark. I haven't found anything I like better in my pre, and I've tried a bunch including JAN Sylvy's (which are good, just not "as" good IMO) Hope you like them too, Jay

I have quite a few GE 12AU7s (only one is labeled made in Canada though). I will try them out - you never know. I also have some Sylvania 6189s and some RCA 5963s to try. I usually leave the tubes in for a couple a weeks when I am trying them out so it takes some time to get to them all.

Edit- I need to try some Amperex :yes: Seem's like I allways get outbid :scratch2:

That happens to me all the time. :tears: I happened to get my Amperex for a couple of bucks from an old guy. :yes: Sometimes you have to pay the big bucks though. This weekend I just bought 4 excellent Tele smooth plate 12AX7s for $100. Not cheap.

 

[ldatlof]

I agree very much, and these seem to apply in a number of circuits I've tried. This includes my Foreplay, a Consonance Basie, and a Scott 350C (instead of 12AT7's). I keep an Amperex in the 350C, a pair of RCA cleartops in the Foreplay (too bright in the Basie), and a pair of Sylvania 6189 mil-spec blackplates in the Basie.

Very interesting that you have had similar results in three different circuits. Have you tried the 6189s in the Foreplay? The reason I ask is I have some Sylvania JHS 6189 (grey plates). Just wondering what is your impression of their sound.

 

[Kegger]

Generally speaking Amperex tend to be my Fav's in most small signal positions.

And like ldatlof they just do everything, no exagerating and no leaving anything out.

 

[jon_s]

Very interesting that you have had similar results in three different circuits. Have you tried the 6189s in the Foreplay? The reason I ask is I have some Sylvania JHS 6189 (grey plates). Just wondering what is your impression of their sound.

I can't really remember if I ever did. It is hard to separate them from the Basie since they sound so nice, big, and 3D. I usually use some GEs or cleartops in the Foreplay and both sound good enough to be below my tube-rolling-desire-threshold. And, if I can avoid rolling, I will avoid rolling

 

[ldatlof]

I can't really remember if I ever did. It is hard to separate them from the Basie since they sound so nice, big, and 3D. I usually use some GEs or cleartops in the Foreplay and both sound good enough to be below my tube-rolling-desire-threshold. And, if I can avoid rolling, I will avoid rolling

That's one of the advantages of the Foreplay, its easy to swap tubes. My TAD-150 pre requires you to remove twelve screws to get to the tubes. Way too much of a PITA. I put in some Sylvania USAF 5751s and it sounds great so I don't bother to change them. My Fisher 400 has the original Telefunkin tubes in it so I figure they are good enough. Also removing it from the case is a PITA.

The RCA black plates should arrive in a day or two so I will put them in for a week or two and see how I like them. Then I will try the Sylvania 6189 to see how they sound. If they don't beat the Amperex then I guess the hunt is on for more Amperexes. I don't have any Bugle Boys................yet. LOL

 

[lorne]

I don't have any Bugle Boys................yet.

Are there really any of these tubes actually left floating in free space on the planet besides the ones that were silkscreened to say that they are BB's? I wonder if $100K would be enough to buy some old equipment and dies and start fresh production of these things — for a profit? :sigh:

 

[jaymanaa]

I have often wondered that myself. I have been told that a big part of the "great" tubes was the people who made them. Very skilled hands (usually female) that had years and years of experience.


Hey, on the BB's or Amperex in general> Did they make 6SL7's? I never see them advertised. :scratch2:

 

[ldatlof]

...Hey, on the BB's or Amperex in general> Did they make 6SL7's? I never see them advertised. :scratch2:

They are not listed in my Philips Factory Valve Code document. Doesn't mean they weren't made but there may be a reason why you never see them.

 

[audiodyssey]

I've been through just about every freakin' EL34 ever made, including the most expensive ones out there. My favorite remains: Tesla E34L vintage brown base with dual stacked halo getters. I'm mainly a rock listener (though I listen to absolutely anything and everything)and these tubes have the slammin' dynamics good for Rock music. As far as new production, the Svetlana Winged "C" is my favorite. I was sadly disappointed with Amperex "DD" getters which seem to lack any "sex appeal." My Gear is a few Dynaco ST-70's which have all been upgraded with some of the more highly reccommended stuff--- Riken ohms, Jensen & Audionote Signal caps, silver wire etc. BELIEVE me when I say, the STOCK 70 can be made to perform alot better with better parts. One of my amps has Roy Mottram's pc board upgrade, which uses 3 12AT7's. This board without a doubt is the best improvement I've ever heard for the ST-70, and benifits not only sonics, but allows each power tube to be biased seperately. And I've tried some of the more famous boards over the years...none come close to this one. If you own an ST-70, TRY THIS BOARD!!! (I have absolutely no affiliation with Mr. Mottram and my purchase was based on a friend's recommendation) I use RCA 6201's in it with square getters and black plates. I've also tried BRIMAR 6060's. For the PAS-3, I use different flavors...my faves are TELE's, Amperex long plate, and tubes made in Japan are fantastic also. So are the EL34's that were produced there. Rectifier is Mullard GZ-34 (labelled Hammond, Sylavania so you can by them cheaper!)
I don't like the testimony of many about the reliabilty and unpredictability of current production. I stick to old stock, and have found ways to aquire the good stuff without being a rich man...

 

[Kegger]

I also run that same ST-70 board from Roy. (Pic in my avatar)

And you are corect it makes the 70 come alive.
Couple suggestions for yu, put 12au7 or 12bh7's in the phase splitters and a 5965
in for the driver tube, you'll get a little less gain/noise/overdrive and better sound.
Also try some 6L6GC's in it as well, after the board upgrade find I like them better.

I'm actually spice modeling that board in multisim at the moment to find what it is
doing and how to improve it, like I say I like it a lot but it's gain is just to high. By
subbing in 12au7 or 12bh7 in the phase splitter section they actually run propper in
the boards stock form and actually run better then 12at7's do. It's the driver tube
area that could use some work and is not optimised for the 12at7 or the 12au7,12bh7.
The best tube in there in stock form is the 5965, I will do some tweeking to mine so
I can run the 12au7, 12bh7 at proper voltages and gain which should be even better.

Just changing a few resistor values, no altering of the circuit needs to be done.

 

[jaymanaa]

On the subject of Dyna 70's, mine has 4- 12AT7's. I'm not sure why. The mod was not a kit, but a circuit published in some magazine. I have never been able to locate a schematic :tears: Anyone ever see a 70 running 4-12AT7's and SS rectification?

 

[Kegger]

Jay I have seen 1 or 2 4tube ST-70 front ends but not sure if I've ever seen a schem.

What tubes does it use again?

Do you know the guy who built it, and could you possably get the schem?
If so I could SIM it up and see how it looks, maybe find some tweeks for yu.

 

[Destructor]

I currently use a 1990's ST70 Series II. It is well built and has been very dependable. It is also a cleaner looking amp but still looks very much like the original. I upgraded all of the coupling caps to MIT's and the input caps to Orange Drops 716P's. The inverter/driver tubes are RCA and the EL34's are Mullard clones. It uses solid state rectifiers. The cap upgrade was a vast improvement but the switch to the Mullards was stunning. The sound is very smooth and detailed. Modification are somewhat restricted by the fact that it uses one large curcuit board for most of the parts including the output tubes. The preamp is a restored/upgraded Mac MX110, it's an nice combination.

 

[jaymanaa]

Jay I have seen 1 or 2 4tube ST-70 front ends but not sure if I've ever seen a schem.

What tubes does it use again?

Do you know the guy who built it, and could you possably get the schem?
If so I could SIM it up and see how it looks, maybe find some tweeks for yu.

12AT7's Keg, You read my mind on the tweaks. Now that my homebrew is up and running I'm thinking about tinkering on the 70. It's been over 10 years since it was built. I'm thinking of upgrading the PT, going back to some serious tube rectification, putting in some better caps throughout, rechroming the chassis and end bells, etc. I plan to use it for a rock and roll only set-up with the Heresy's stacked on top of the Dorians and use the 4ohm tap. I would like to run KT90's with a bit more confidence. The circuit would be a nightmare to trace as it is jam packed. Thanks

Now a tube question I got some NOS RCA red base 5691's for the homebrew as posted above. Man do they sound good but I have a problem with them that I was hoping would fix itself as they got broken in. When I first fire up the amp and start playing music they are so microphonic that if I tap on the table where the amp sits they crackle. It's worse at low volume and goes away completely if I run it wide open. After about two hours they settle down just fine. This doesn't happen with any other tubes, so I don't think it's a problem with the amp. Any ideas? Thanks guys, Jay

 

[Kegger]

Jay what voltage is actually on the plates of those tubes?

I have heard that 6SN7 and 6SL7 can be microphonic when run at to low a plate voltage.

 

[jaymanaa]

Jay what voltage is actually on the plates of those tubes?

I have heard that 6SN7 and 6SL7 can be microphonic when run at to low a plate voltage.

205-210

 

[Kegger]

Well that should be plenty!

I'm not sure what your issue might be.

Microphonics in general is not an alarm per say, and some have said the best there
system has sounded was with tubes where they really had to do some dampening
vibration techniques to get the unit not be so Microphonic which they gladly did as
the sound they were getting with these tubes was something they didn't want to be
without as they liked them that much. Which may well be what you are experiencing. :scratch2:

 

[audiodyssey]

Couple suggestions for yu, put 12au7 or 12bh7's in the phase splitters and a 5965
in for the driver tube, you'll get a little less gain/noise/overdrive and better sound.


I'm actually spice modeling that board in multisim at the moment to find what it is
doing and how to improve it, like I say I like it a lot but it's gain is just to high. By
subbing in 12au7 or 12bh7 in the phase splitter section they actually run propper in
the boards stock form and actually run better then 12at7's do. It's the driver tube
area that could use some work and is not optimised for the 12at7 or the 12au7,12bh7.
The best tube in there in stock form is the 5965, I will do some tweeking to mine so
I can run the 12au7, 12bh7 at proper voltages and gain which should be even better.

Just changing a few resistor values, no altering of the circuit needs to be done.

I'm going to try your suggestions here tommorrow...I think I have a 5965 or 2 around here somewhere. As for other tweeking you might do, please keep me informed of what you find. I absolutely HAVE to mess with things even if they're just fine, so I'll go along with any improvements you might want to share. Thanks, Kegger

 

[jaymanaa]

Well that should be plenty!

I'm not sure what your issue might be.

Microphonics in general is not an alarm per say, and some have said the best there
system has sounded was with tubes where they really had to do some dampening
vibration techniques to get the unit not be so Microphonic which they gladly did as
the sound they were getting with these tubes was something they didn't want to be
without as they liked them that much. Which may well be what you are experiencing. :scratch2:

That seems to be my situation exactley. I think I will run them all weekend and maybe try putting some o-rings on them. They look so much different (internally) than any other 6SL7. That combined with the red bases and 5691 number had me wondering if maybe they weren't really designed to be used in audio? Anyone know what the red bases are all about? I'll try a pic here too, Jay

Edit- Are there other ways of dampening other than o-rings?