• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Which EL84

What are the operating voltages it subjects your outputs tubes to? If you don't know , what's the amp? Many amps need 7189 spec tubes as they are pushing voltages way above EL84 specs.

I've had good luck with JJ's so far and they are well priced. You can get them for $40 a quad. They are known to take some out of spec voltages too and sound really nice. From what I read on this form and others there is an agreement on this.

There are Russian EV etc. rated tubes which can take even more abuse according to many on the forms. You'll probably hear from many users on the these as they can be quite well priced.

New Sensor's Gold Lions are supposed to sound great for close to 3 times the price. May be best sounding of new production. Don't know if they can take out of spec voltages.

Shuguang Treasure Series has a Pavane T series in the upper price range about $95/Pr. just out which should be sonically great too as the other tubes in this series are well liked on the forms. Can they take out of spec V. is another unknown.

My question for the many amps that need 7189 or higher spec why not make tube adapters to plug in your amp which take the new production 7868 or 7591 tubes which are octals and apparently have close to the same drive requirements as the EL84/7189. Space could be a problem on some so they may have to be sky wired. EH ones go for about $80 a quad and should last for many more hours too at the lower voltages. Plus you could have fair bit more power with adjustments! HH Scott amps specified 7189 tubes and in the later seies went to 7591 tubes with larger output transformer. Their amps ranged from 30-40 W/CH. You would loose a bit in power because of the 7.6-8K ohms input load found on most EL84/7189 amps, but may gain in sonics. I don't think it would hurt sonics going from Tung-Sol's 6.6K spec. for fixed bias. Actually the spec. for Cathode Bias which many EL84 amps use is 9K for Pentode hookup of 7591's. The Tung-Sol specs 23-45W depending on setup and voltages. It is said they run nice and cool in the under 400V range too.
See attachment for specs.

Hope that helps!

Randy View attachment 7591.pdf
 
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I never had any experiences with Chinese tubes, Soviet 6P14P are the cheapest EL84 you can find, but EI Yugoslavia EL84 or Tungsram EL84 sounds better, nice tubes to listen to.


Might be amplifier specific as I think the 6P14P-ER sounds better than anything I've tried except the vintage Teles I have on hand. I also have EI, JJ, and a couple of Tungsram lurking in my tube stash. The JJ sound nice but don't seem to stand up well in American or Japanese made amps that push these tubes hard - in some cases their demise is rapid and fiery... :hot:
 
I'm using the JJs in three different Red Light District amps- after three years, they're all still going strong.


My experience has been very different.. :D I relegate them to voltage regulator service as they don't survive in my vintage Realistic or Scott amps. (recently gifted to a friend.)

In the case where the amplifier adheres to reasonable tube manual operating conditions for a 6BQ5 the JJ ought to be fine.. Most vintage American and Japanese amps unfortunately don't, and were either designed for more rugged 7189A or Japanese 6BQ5 which had a lot more in common with 7189(A) than a standard 6BQ5. (I learned this the hard way when I was still in the business of fixing vintage amps.)

It occurs to me that the OP was hoping for a simple answer, without knowing the specifics of his amplifier (design) this is a question without an answer, and even knowing that what I like and what he likes could be different..
 
I never had good opinion about Russian tubes, except very few types, I remember when I was 15, I started to experiment with VHF transmitters, none of 6P14P couldn't start to oscilate on 100 MHz, and almost every other EL84 I puled out from old tube radios worked perfectly :) ... could be amplifier specific, and could be this experience from young days has some influence too!!!
 
I never had good opinion about Russian tubes, except very few types, I remember when I was 15, I started to experiment with VHF transmitters, none of 6P14P couldn't start to oscilate on 100 MHz, and almost every other EL84 I puled out from old tube radios worked perfectly :) ... could be amplifier specific, and could be this experience from young days has some influence too!!!


The standard 6P14P and the -EV, -ER variants are quite different based on samples I have on hand. The -ER/EV are built to higher standards to the best of my ability to determine.

FWIW JJ EL84 and many others will also oscillate at >100MHz if given the chance based on direct experience, however this problem is easily resolved with grid stoppers and good wiring practices. The EL84 wasn't really designed AFAIK for RF service. The 6CW5/EL86 was commonly used in tube CB radios here and can operate at 27MHz...
 
As ever, some varied replies. Thanks.

The amp is a homebrew DIY Paradise Simple EL84. B+ is 290v and sounding superb.

I currently have 4 very nice 6P14p-ev tubes doing push pull duty. But the 2 driver EL84s are unknown Chinese things, which although better than expected, are not as good as the Russian tubes in the bass department.
It's these i'm mainly concerned about.
If i can get away with just replacing these two then great.
Need some deep good quality bass.:)
 
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Thanks Kevin for info on JJ's as I have a friend in the US getting a Scott 299(A) redone and he was wondering about tubes. They seem to survive fine in my Eico HF-12 amps using a variac for now to run them just above 110V for normal B+ spec'd for EL84.

Check this very interesting mod from Dave Gillespie!

There is a whole thread on it diytube under in stereo 35 under "improved ST-35 performance". It could help tubes last and sonics on many EL-84 to 7591 amps or other low voltage bias (under -37V) amps for low $.

http://www.tronola.com/A_New_Look_At_An_Old_Friend_Rev0.pdf

I've got to get some of those 3 critters ( LM337 neg voltage reg's) to try in the new year!

Thanks very much Dave for that!

Randy
 
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I wrote a long post before I realized that you said EL-84 and not EL-34 so I deleted it. I have not used EL-84s that I know of. All I can say generally about brands is that all the NOS tubes are better but may not be worth the price to you depending on exactly what you want to do. If it is not worth it to you then I think I like the high grade Svetlanas or the new production Mullards the best. I don't know if that would apply to EL-84's though
 
What are the operating voltages it subjects your outputs tubes to? If you don't know , what's the amp? Many amps need 7189 spec tubes as they are pushing voltages way above EL84 specs.

I've had good luck with JJ's so far and they are well priced. You can get them for $40 a quad. They are known to take some out of spec voltages too and sound really nice. From what I read on this form and others there is an agreement on this.

There are Russian EV etc. rated tubes which can take even more abuse according to many on the forms. You'll probably hear from many users on the these as they can be quite well priced.

New Sensor's Gold Lions are supposed to sound great for close to 3 times the price. May be best sounding of new production. Don't know if they can take out of spec voltages.

Shuguang Treasure Series has a Pavane T series in the upper price range about $95/Pr. just out which should be sonically great too as the other tubes in this series are well liked on the forms. Can they take out of spec V. is another unknown.

My question for the many amps that need 7189 or higher spec why not make tube adapters to plug in your amp which take the new production 7868 or 7591 tubes which are octals and apparently have close to the same drive requirements as the EL84/7189. Space could be a problem on some so they may have to be sky wired. EH ones go for about $80 a quad and should last for many more hours too at the lower voltages. Plus you could have fair bit more power with adjustments! HH Scott amps specified 7189 tubes and in the later seies went to 7591 tubes with larger output transformer. Their amps ranged from 30-40 W/CH. You would loose a bit in power because of the 7.6-8K ohms input load found on most EL84/7189 amps, but may gain in sonics. I don't think it would hurt sonics going from Tung-Sol's 6.6K spec. for fixed bias. Actually the spec. for Cathode Bias which many EL84 amps use is 9K for Pentode hookup of 7591's. The Tung-Sol specs 23-45W depending on setup and voltages. It is said they run nice and cool in the under 400V range too.
See attachment for specs.

Hope that helps!

Randy View attachment 202103

Ditto on the JJ's !
 
RCA 6BQ5 for bass.
Mullard EL84 for mids.
Telefunken / Amperex for trebles.

I have x-ray photos of my RCA 6BQ5. Surprise, beam tetrode inside!
Definately not the same animal as EL84/7189. I do not know if this
applies to all RCA 6BQ5, or I just found something weird and rare?

I have JJ and GT branded EL84's, also Fisher (Made in England) 7189.
All genuine pentodes, X-rays of these look nothing like the RCA.

Search the forum for X-ray, you will find my thread with those pics.
 
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I believe that E84L / 7230 by Siemens are the best, followed by RCA 6BQ5.
The Russian 6P14's sound very open and dynamic too and it's a good deal due to there low price and availability.
But after all I believe that most important is the topology and the OPT that you will use in your project
The type/maker of the tubes is the last thing you have to deal with.
 
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Some sellers quote different figures for matching. Are any of them really meaningful or useful?

Example one.
Mutual Conductance is:
Tube 1 86
Tube 2 86
Tube 3 85
Tube 4 85

Example two.

Ia S
mA mA/V
1 - 6P14P-EV test results 51.0 13.0
2 - 6P14P-EV test results 51.0 13.0


Example three.
Ia Ig2 S -Ig1
mA mA mA/V uA
1 - 6P14P-EV test results 43.0 4.0 11.0 >0.2
2 - 6P14P-EV test results 43.0 4.0 11.2 >0.2
 
Some sellers quote different figures for matching. Are any of them really meaningful or useful?
<snip>

Example three.
Ia Ig2 S -Ig1
mA mA mA/V uA
1 - 6P14P-EV test results 43.0 4.0 11.0 >0.2
2 - 6P14P-EV test results 43.0 4.0 11.2 >0.2

Of the three IMHO example 3 is definitely the most useful, and while I would have liked to have known the plate voltage it does indicate that this particular pair is matched to better than a couple of % under conditions reasonably typical of use. The others do indicate that the tubes are tested and match to some degree. All are useful in the sense that they indicate that the seller cares enough about his reputation and the quality of his product to properly test them prior to sale.
 
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