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Tone of 7189 compared to 6BQ5/EL84

Ben S.

Member
Messages
2,181
Does anyone have experience or opinions on the tonal differences of 7189's compared to 6bq5's? Especially comparing the same manufacturer.

I am mainly interested because of the higher plate voltages. I am not terribly worried because my amp has power scaling and that brings the voltage down, but when opened up all the way, the plate voltage is around 350v.
None of my tubes red plate and the manufacturer said the amp usually runs in the low 330's when full out.

Tone wise, I love my Sylvania black plates the most so far. So I may just give the Sylvania 7189A's a try. Do they make black plate 7189's?
My 50's Mullards are great, but the Sylvania have more clarity and seem give the amp better dynamics with picking pressure and have a little more harmonic content. I even like my late 50's Mazda over the Mullards. But they are all good.

Edit: I found that Sylvania did make a black plate 7189.
 
Last edited:

59Vampire

Platinum Supporting Member
Messages
4,439
First of all, it should be mentioned that black plates were designed to make a more rugged tube. They dissipate heat better. Does this sound better to you thana a gery plate?maybe maybe not its all subjective. a 7189 is a beefier tube designed to handle more current and in many cases offers thicker supporting rods or dual getter support. Tonal variation would be minimal. I have mullard 7189s and bugle boy 7189s. In comparison to their el84 brothers i dont think thereis much difference tone wise.
 

Ben S.

Member
Messages
2,181
Tonal variation would be minimal. I have mullard 7189s and bugle boy 7189s. In comparison to their el84 brothers i dont think thereis much difference tone wise.
That is very much what I wanted to find out about. Especially from those who have played with both in the same amp.
Thank you very much, I appreciate the feedback.

Why did I ask about the black plates for the Sylvanias? Because I very much like the sound of mine. "Like" being the subjective word; I agree it is all very much subjective.
 

Timbre Wolf

Hyperspatial Gravity Surfer
Platinum Supporting Member
Messages
10,089
Tone wise, I love my Sylvania black plates the most so far.
I don't have 7189, so no comparison - sorry.

I just wanted to add in that I am also particularly fond of black-plate Sylvania 6BQ5. And, like you, I also prefer them over genuine Mullard, Valvo, and Heerlen Amperex ('60s). They've a thicker tonality than most EL84, but better clarity than the above EL84 choices. Quite nice!!!

- Thom
 

slider313

Gold Supporting Member
Messages
8,254
I've had both RCA 6BQ5's and 7189's in a Goodsell Super 17 and found they sound almost identical.
 

Kiwi

Silver Supporting Member
Messages
4,078
As I understand it:

The main point of using 7189s is their ability to take higher voltage. They're rare and expensive now. If you don't need 'em, the diff in tone may not be worth the high cost.

One alternative is the Russian EL84M, which can take higher voltages. Do a Google search from some current online sellers for comments and description.

TubeDepot's comments [sic]: A military-spec version of the standard Sovtek EL84 - the Sovtek EL84M's extended voltage tolerance - improved plate dissipation - and rugged construction make it equivalent to the RCA 7189. Chosen by Matchless for their designs - the EL84M also features higher transconductance - more power - and longer life than the less expensive EL84 - making it perfect for hi-end audio applications. However - many musician's prefer the regular EL84's warm distortion to the EL84M's tighter - cleaner tone. For all Hi-Fi users - the EL84M is definitely the tube of choice.

I once tried EL84M's in an early-70s Marshall 20-watter, which delivered over 410v to the plates according to my tech. The EL84M's sounded stiff, harsh and broke up badly... but they didn't redplate. That would explain why they are used in stereo (hi-fi) amps. That's where my four EL84M's ended up, in an old Knight hi-fi tube amp.

I dunno about the Matchless claim (above) ... I have a DC-30 and I know it's hard on EL84 tubes, but it sounds too sweet to be that stiff EL84M breakup tone I once heard...

Anyway, a bit of a digression from 7189s.

=K
 

Ben S.

Member
Messages
2,181
Thanks guys.
I had done some reading and also spoke to my main tube dealer. Most of the information out there is more about Hi-Fi applications for the 7189 -- trying to get more power out of the 6bq5 platform.

I was just curious about other people's experience in guitar amps. Since my amp can run hotter than some other EL84 amps, I was a little bit concerned about tube life. However, I end up having to use the power scaling so much (man, this would solve so many arguments with sound guys if more people had it) that the voltage ends up coming down anyways and I may be worrying about nothing.

Since there doesn't seem to be big tonal differences, I think I it might be worth it to try and find an inexpensive used set of Sylvania 7189's to compare for myself.

Yeah, I love the Sylvanias BP's. I need to stock up on some more backup pairs. I just got another beautiful set of slightly used ones on Ebay for $48 delivered! They test very strong and almost new and sound great.
 

Timbre Wolf

Hyperspatial Gravity Surfer
Platinum Supporting Member
Messages
10,089
Yeah, I love the Sylvanias BP's. I need to stock up on some more backup pairs. I just got another beautiful set of slightly used ones on Ebay for $48 delivered! They test very strong and almost new and sound great.
Yep - they're still often available at bargain prices. Enjoy!!

- T
 

jcs

Member
Messages
8,086
just dont exceed 60-70% dissipation with any el84 tubes and expect long life imo.
 

Ben S.

Member
Messages
2,181
just dont exceed 60-70% dissipation with any el84 tubes and expect long life imo.
Yeah, that is the thing that is starting to bother me the more I think about it. My Weber BiasRite was measuring 347-350v and 46-49ma when the power scaling was completely taken out of the circuit. As you engage the power scaling, the levels come down to more normal readings (normal in my mind at least) for EL84 amps. I think I am going to open it up and take some readings without the BiasRite.
 




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