Tube Guide?

[Guest davidness]

...(I was power cycling while the amp was already warm/hot. Isn't that okay?)

NO - that is NOT OK with a Sovtek or Sino 5AR4.

Thanks for letting me know. I appreciate it. How else would I learn? I'm just glad it was the relatively inexpensive Sovtek 5AR4 rectifier that I blew rather than something more expensive.

If you know where I can currently source a really nice Mullard rectifier, let me know through email/pm. I promise not to blow it up (on purpose).

[gartenman]

What is noteworthy is how the Mullard and Amperexes differ with vintage....especially the Mullards, which have quite a variance from earliest to later vintages. I Like Tele 12AX7s in my vintage Mac gear, Amperex 12AX7s in most modern gear, and earliest Mullards are a very good phono tube.

This is a very good point! I also agree with the comment about Joe's Tube Lore....he hates 12AX7s!!! Remember to factor in gear synergy into the quotient which as mentioned by Audio Nectar is noteworthy.

[kevinmi]

I recently purchased my first tube amp from a fellow forum member, a Bob Latino VTA120 (ST-120), that came with (4) Valve Art KT-88's and (3) Mullard CV4024 in the 12AT7 positions. I've driving a pair of Klipsch RF-7's.

I am a newbie, so these impressions are geared toward tube amp novices, but I hope others will learn something from my experiences.

I've never heard any other tube amp, but this thing sounds awesome, which surprsed me since I had been drving my RF-7s with the fairly expensive solid state Yamaha RX-Z7 AV Amp.

I am hooked on the tube expereince (God help me), so let's see how much I can squeeze out of the Latino VTA-120.

I immediately bought a quad of Gold Lion (reissue) KT-88's, but I didn't like their sound as well, so I switched back to the Valve Arts. I only just realized that new tubes do require a break-in period (I've read it takes about 100-hours), so the Gold Lions are back in. After all, all the reviews have been very positive. I've only got 20-30 hours on them now, but I think they're getting much better, and now already equal the Valve Arts. I think they're on their way to greatness. A would LOVE to try a quad of EAT KT88's.

I also learned that the input tubes are even more important to the sound than the output tubes, so I started looking at options to the Mullard CV4024, which get great reviews also (plus it's cheap and plentiful... for now). I also learned that the 'center' input tube is the most important of the 3, then the left/right pair which should be somewhat matched.

Through various means (eBay), I have now ordered a quad of NOS Valvo Goldpin 12AT7WA's, a pair of NOS RCA Black Plate 12AT7's, a pair of Telefunken ECC801S (supposedly the best 12AT7 tune there is), and a single Telefunken E81CC (very similar to the ECC801S).

I have not yet received any of these input tunes. I think that this selection should give me an idea of what rolling 12AT7 tubes can do for the amp. The only other tube that seems to stand out are the Amperex Bugle Boy's, so I'll probably pick up a set of those one day as well (unless I simply bite the bullet and buy a matching NOS set of the Telefunken ECC801S).

Also, the amp came with both a Sovek tube rectifier, which 'flashed and died' within a few hours, but I was also given a solid state Weber Copper Cap rectifier, which is now in there. I've heard the rectifier doesn't affect sound much (if at all), and I'm hesitant to put in a more expense (aka Mullard) rectifier given the unknown reason that first one blew so quickly. (I was power cycling while the amp was already warm/hot. Isn't that okay?)

I'll be certain to post my impressions of the various 12AT7-class input tubes once they get here (some from the Netherlands and from Germany).

Please respond with any of your own impressions of tube rolling the Dynaco ST-70/ST-120 (or similar) as it pertains to this thread. I, also, am interested in the KT-88 vs. 6550 tube.

I'm currently running a Weber copper cap SS rectifier, since I had the same blow out problem with my tube rectifier. I just bought a new JJ tube rectifier I'm going to try out this weekend to see if I hear any difference in my ST 120. I'll be using the Sovtek KT88's and the Mullard 4024's in the front. I'll report my findings in a few days.

I just put in one of the new Sovtek 12AX7 LPS tubes in my preamp to try out. I'll use it this weekend and see how it sounds.

[Paul Hale]

Part of "gear synergy" is considering the many parameters affecting the tube inside the amp. High voltage on the plate is one of the main ones. To answer one of the original questions, one of the differences between a 6550 and a KT88 is that the KT88 is a high voltage tube. It is built to operate under higher voltages. Gartenman, I didn't say anything about the sound of higher voltage ratings, I was talking about safety and survival. Sorry I wasn't more clear. But if you want to consider just the sound, I'd say that wired in triode with 525 volts on the plate, a KT88 will sound better than a 6550 that's burned up. There are plenty of amps with less than 400 volts on the output tube plates, also. It's just good to know what you have.

The 6DJ8 wasn't designed for audio, either, but it's used in many amps.

Old Telefunken 12AX7s may sound good in vintage gear. I'd like to offer a clarification that they may sound good in vintage gear with high frequency rolloff that has old worn out capacitors with no highs. To many, they're thin and bright, but can sound "clear." Joe says the same in his "Tube Lore." If you've got a rebuilt vintage amp with new caps and maybe a few small circiut updates, a new reissue Tungsol and/or a LPS can sound great.

The original poster said money was an issue, which made me want to offer the advice of new production tubes. But I'm no guru. Just trying to help. A reliable tube guide would be nice, but there sure are a lot of variables (amp, system, music, ears, room). I guess that's part of the fun, finding what tubes work well for you. Don't be in a hurry.

PH

[Groomlakearea51]

To many, they're thin and bright, but can sound "clear;

How that "clarity" is perceived (out of horns....) is also a product of the room configuration and "treatment". I won't admit it..... but I've tried some "new stuff" which is every bit as good as some of the NOS and about 1/2 the price..... Not always.... but things are getting better with those factories.

[gartenman]

Paul, I read your profile and noted you are a cellist. I apologize, I was just making a joke. As a former professional musician we always had jokes about drummers, bass players, singers etc. I've never met a musician who didn't have a sense of humor. I told my neighbor about you as she is from Oakland and went to the Oberlin Conservatory and plays viola. You 2 probably know each other. She's the one who thought you would get a kick out of the jokes. Again, I am sorry no offense was meant. With whom do you play and what school did you study?

[Marvel]

I just put a Telefunken 12AT7 in my Fender Pro Junior. They bias the outputs way to high, but I will remedy that soon (like full on12 watts before you play!)

Bruce

[gartenman]

I just put a Telefunken 12AT7 in my Fender Pro Junior. They bias the outputs way to high, but I will remedy that soon (like full on12 watts before you play!)

Bruce

thats a killer amp!! i thought it used 12AX7s....did you put the 12AT7 in it to tame the beast and if so how did it work? i do a similar thing with my '59 Fender Bassman by replacing all 3 12AX7s with 12AY7s. good luck!!!

[Marvel]

The PJ does use 12AX7s, but the RCA that was in it decided to give up the ghost. A little less gain sure isn't going to hurt. It's also quieter than the Fender tube that came in it. The two things I want to do with this are to bias the EL84s at about 8 watts, and replace the volume pot with an audio taper instead of a linear. You get very little adjustment range the way it is now.

I'm not much of an electric player, but I would like to get this where I can use my 1940s lap steel on it. I've used a 50 watt Yamaha SS amp for a long time (paid a guy $50 for it... fixed it in about 20 minutes). It is so quiet, you can hardly tell it's turned on.

[gartenman]

replace the volume pot with an audio taper instead of a linear

great idea! i did the same thing many years ago and can't be happier i made the change...

[USNRET]

Hope this is somewhat related. If you started to try the tube rolling thing , what component would make the most dramatic difference Phono stage, CD, preamp or amp (assuming that all current tubes are behaving properly)?

[gartenman]

from what i've been told preamp tube changes will make the biggest sonic change...hope this helps

[USNRET]

from what i've been told preamp tube changes will make the biggest sonic change...hope this helps

Notice from the sig that we have very closely related equipment. I need to study your tube selection for a bit.

I have Tercel / Jolida > Peach > VRD stereo version > Belles

[Audible Nectar]

"Old Telefunken 12AX7s may sound good in vintage gear. I'd like to offer a clarification that they may sound good in vintage gear with high frequency rolloff that has old worn out capacitors with no highs"

They sound very good in rebuilt McIntosh amps and preamps, too, and with a host of differing parts packages. I have two sets of MC30 (one with PIO caps, one with Sonicap Platinums) and both with extensive and particular rebuilding, and find Tele Smooth 12AX7 to still be the tonality choice in these. And I've tried a BUNCH of 12AX7 in these and Teles do it best for me. I don't think it's as much the "sludge" of old caps as much as it's what the Macs are happy with.

That said, I agree on Teles not being my faves in most other apps. I've heard Teles in Cary and other modern gear and HATED them. My vintage McIntosh exploits are a specific "gear/speaker/tonality" combo that I really love....I basically ignored Joe on this one, because vintage doesn't seem to be much his "bag" (and MC30's certainly aren't). Joe's after "wide open/unveiled/unrestrained", and in many respects I find some of his advices on 6DJ8 worthwhile, but we definitely part ways on Mac....and 12AX7s in general. I like 12AX7 preamps AND 6DJ8 preamps too, but for different reasons, just as I like vintage AND modern approaches each for thier different reasons.

[clermontcop]

Kevin I have some 5AR7 Groove Tubes available (rectifier), if you need any. Let me know.

[kevinmi]

Kevin I have some 5AR7 Groove Tubes available (rectifier), if you need any. Let me know.

Hi Matt, I just put in a new JJ rectifier tube and it seems to be working fine. I can always use a backup if you want to send one my way. You don't have any 12AX7 tubes laying around, do ya?

[gartenman]

any 12AX7 tubes laying around

i may, what are you looking for?

Gary

[gartenman]

from what i've been told preamp tube changes will make the biggest sonic change...hope this helps

Notice from the sig that we have very closely related equipment. I need to study your tube selection for a bit.

I have Tercel / Jolida > Peach > VRD stereo version > Belles

i'll be glad to help you, i have been told by many to change the 2AX7 in the Jolida CD player to a 12AT7 or 5751. Sweetened the sound for me and took off any harsh edginess to the tone, i may have a couple 12AT7s if you want to try but out of 5751s, i'm retired military also...

[USNRET]

Thansk for the help, 'preciate it. I will have to crack open the Jolida and check inside. I bought the "reference level" from hotrodaudiomod and I know they gave me the stock tubes that were removed, I don't remember if they told me what went in.

Here is the tubes that I have but all I can o is read the tubes/boxes cause I know nadda:

Tercel has: 3 Electro Harmonix 12AX7EH with what I assume is a date stamp of 08 01

VRD_ST has Valve Art KT-88s ("matched" per sticker on the boxes); JJ ECC83s, JJ ECC 82 and Sovetek 5AR4

Peach (didn't open it to see what's there but I asked Mark to do what he thought best when I sent the preamp in 6-7 months ago to get it re-freshed)

Here are the tubes I have collected as either package deal on the buy or as removed as stock on the Peach and Jolida JD100A:

2 ea RCA 12AX7A from Brent Jesse Production Type "A" marked 1500/1500 Dated 10-17-08

2 ea. RCA 12AU7A "Cleartop" dated 10-21-08

3 ea. Ei 6DJ8EG (IIRC removed from Peach)

1 ea. unknown 12X4

2 ea. Electro Harmonix 12AX7A (removed from the Jolida by Hotrodaudiomods when they modded mine new)

4 ea. Valve Art 350Bs, boxes are taped together and marked on end of box 1 thru 4 w/marker and a round yellow sticker that has "70" written on it.

4 ea Gold Loin KT-88sw/ a sticker that says lp:76 & Gm:8300 on each box

Thanks again, gartenman.

Mike

[kevinmi]

any 12AX7 tubes laying around

i may, what are you looking for?
Gary

Gary, I'm looking for for some single tubes for my preamp. I need something that is extremely quiet, and I'm wanting to get that warm, tubey vintage sound. I'm running a Tung-sol in the center position, with Groove Tubes on the left/right (3 tube preamp with 6x4 rectifier tube). I've tried new EH tubes and a Sovtek 12AX7LPS, and I'm not liking either. I'm thinking I need to go vintage. Any suggestions?