[JakeJ]

Your point is well taken.  When it comes to tube substitution, the best source of information is the manufacturer.  I acknowledge in this instance, I took Kevin's word on it and didn't check with manufacturer; I have just sent the manufacturer an e-mail.  I'll let you know what he says.  But I would add that it's one thing to diasagree but it's another thing to be disagreeable.  When we begin to denigrate the values or intelligence of others, we are, in my opinion, heading out of bounds.  The precesence of civility and courtesy is what makes Audio Circles a much better forum than the Audio Asylum.  Just my 2 cents.  Happy listening all.

I concur with this statement.  The "Laws" of physics are indeed laws, however in the world of electronics we have found we can bend the hell out of them. 

I also think it's best to consult the designer/manufacturer of the equipment/circuit as they are the best judge of how much further the circuit can be "bent" by a tube substitution.  I'm guessing in the early days the tube manufacturer just made the tube type to the specs set down by the designer's requirements for his circuit, mainly radio purposes.  My Google for a governing body of tube types and specs came up with this:
https://en.wikipedia.org/wiki/RMA_tube_designation  Don't know what they used before the 1940's.

I, for one, will be very interested to hear what the mfr of Starchild gear has to say.

As to ACHiPo's situation, I hope you find your audio nirvana all over again with a new preamp.  Question, ACHiPo, are you using the PSE with the same amplifier you used with before putting it into retirement?  Same speakers?

[E55l2]

There is even a special word for this "bending" : stupid.

I am sure that every good tube equipment manufacturer is aware of the design parameters of tubes and that they don't make mistakes as i discribed before. If they do use this bending: avoid them, there equipment is not reliable.

[mcgsxr]

Could stupid actually mean not ideal?  I imagine certain tubes can be used that may not return the best performance.   

[Escott1377]

I have used the 7DJ8 as a replacement for the 6922 w/ absolutely no issues.

I did this with the Manley Chinook for years.

When I owned my Manley Shrimp, my favorite input tubes were the 6829's which are an industrial version of a 12 AV7.

Same pin out as the 12AT7, just slightly less gain.  Used for years, preferred their sound over the Mullard 12AT7 which I have heard in some circles be called the gold standard for 12at7 tubes.

BTW - in the case of Manley, I know for a fact that the owner of Upsclae is great friends with the owner of Manley.  So much so, that a special edition of the phono stage that I mentioned above was branded as the "Upscale Audio" edition.

"Stupid" is a strong word to toss around, but then again, it is the internet.

[E55l2]

It's indeed a strong word exactly as you say " i have no issues"

Did your amplifier really performed excactly the way before or you just mean: i cann't hear it...?
Did you measured he performance?

Btw we are talking about 7dj8 vs 6dj8.

I have used the 7DJ8 as a replacement for the 6922 w/ absolutely no issues.

I did this with the Manley Chinook for years.

When I owned my Manley Shrimp, my favorite input tubes were the 6829's which are an industrial version of a 12 AV7.

Same pin out as the 12AT7, just slightly less gain.  Used for years, preferred their sound over the Mullard 12AT7 which I have heard in some circles be called the gold standard for 12at7 tubes.

BTW - in the case of Manley, I know for a fact that the owner of Upsclae is great friends with the owner of Manley.  So much so, that a special edition of the phono stage that I mentioned above was branded as the "Upscale Audio" edition.

"Stupid" is a strong word to toss around, but then again, it is the internet.

[FullRangeMan]

Escott do you would inform how many thousands hours these your 7DJ8 lasted in your amp?

The 12AVT7 gain is a secondary parameter it just will sound a bit different, in the case of the 7DJ8 the Cathode heating is a basic parameter for the tube operation.

[Starchild]

There is even a special word for this "bending" : stupid.

I am sure that every good tube equipment manufacturer is aware of the design parameters of tubes and that they don't make mistakes as i discribed before. If they do use this bending: avoid them, there equipment is not reliable.

It would appear there is no reason to discuss this any further.  You've already slammed the users as not serious listeners and now if a manufacturer happens to endorse the tube, their equipment must be unreliable.  Out of curiousity I read all of your previous posts to get a sense of who you were. You appear to be very knowledgeable about tube amplification and you write like a technician.  I'd suggest that you soften your tone a bit and cast fewer aspersions.  I hope you will accept my comments in the spirit they've been given.  My intent is not to start or get involved in a flame out so I'll probably not add anymore posts to this string beyond reporting back on the comments of manufacturer of my tube amp and pre-amp (Margues Audio).

[E55l2]

What would people say if there amplifier was damaged by using the wrong tube?
What would they say if there was a fire?
What would they say if somebody was injured because of......

This is not a game. Better save then sorry i guess.

[mcgsxr]

I think the point being made is that one can express oneself about a topic one is knowledgeable about without resorting to labeling the actions of others as stupid. 

Perhaps you will consider including that perspective in the future when sharing the information you have, and feel is important.

We love insights around here!

[SteveFord]

I've always found that asking the manufacturer is the way to go. 
The tube vendors may be quite knowledgeable about their product but the manufacturer will be the one to listen to.
 

[Escott1377]

I've always found that asking the manufacturer is the way to go. 
The tube vendors may be quite knowledgeable about their product but the manufacturer will be the one to listen to.
 

A little bit off topic, but a little bit on topic.  I recently added a pair of Emission Lab 300b mesh plates to my set up.  These run at about 70% operating voltage of a standard 300b tube so they are not a direct drop in replacement.  The US distributor was kind enough to call my pre amp manufacturer and have the discussion between them before selling.

Great example of good customer service.

[E55l2]

There is a differance between doing stupid and being stupid.
And i mean the first.....

I think the point being made is that one can express oneself about a topic one is knowledgeable about without resorting to labeling the actions of others as stupid. 

Perhaps you will consider including that perspective in the future when sharing the information you have, and feel is important.

We love insights around here!

[E55l2]

This is very good and of course if manufacuturer of the amplifier looks at the schematic and look at the data of the tube he knows if it is possible to plug and play with this mesh tube.

The problem of the topic starter is however different. We already know from the start that it is not plug and play. The filement voltage has to be changed.
Of course the amp manufacturer can be asked to change the heater voltage for the new tube but that is a different question.

A little bit off topic, but a little bit on topic.  I recently added a pair of Emission Lab 300b mesh plates to my set up.  These run at about 70% operating voltage of a standard 300b tube so they are not a direct drop in replacement.  The US distributor was kind enough to call my pre amp manufacturer and have the discussion between them before selling.

Great example of good customer service.

[mlundy57]

I will be the first to admit I am not a seasoned tube person. I don't know how long tubes take to burn in but when I have bought matched pairs or quads of NOS tubes they were burned in for 70 hours before shipping.

As for sound, different manufactur's tubes of the same type can sound very different. My PrimaLuna Prologue 4 (power amp) came with PrimaLuna branded stock tubes; 4 EL34's, 2 12AU7's and 2 12AX7's. I was not overly impressed with the sound. While it had the warmer tube sound, it gave up a lot of definition and clarity to my solid state amp.

Upon the advice of the person I bought the Amp from I replaced all the tubes. I went with Svetlana Winged C EL34's, Cifte 12AU7's and Telefunkin Black Diamond Smooth Plate 12AX7's. The difference in sound was anything but subtle, it sounded like a completely different amp. Now I had the warmth of the tube amp but the clarity and detail of the solid state amp.

So both the break in and tubes themselves can make a big difference in the sound.  Also, having somebody familiar with a particular piece of equipment and how it performs with different tubes from both technical and sound quality perspectives is very helpful.

Mike

[ACHiPo]

Wow!  While I was listening to the tubes bed in and basically getting on with life, y'all have been busy little bees here!

There is a differance between doing stupid and being stupid.
And i mean the first.....

E55, please check your attitude and language.  While you may have valuable knowledge to share, the word "stupid", regardless of whether you mean doing or being, comes across abrasive and more than a tad bit offensive.

As an update to my "stupid" actions, the preamp is sounding more like I remember.  The bass has tightened up considerably in the last 24 hours of playing and resting.  The midrange continues to bloom nicely, and the detail is getting sharper.  Paul Chambers's bass on "So What" is not quite as tight and a bit more bloomy than with either the Rowland Consummate preamp or running balanced outputs straight from my Oppo 105 to the amps, but it listenable and "back in its box" compared to how it dominated the entire soundstage a few hours ago.  A quick listen to Deep Purple confirmed that the bass was back to a more reasonable level and control. Volume is also up a bit.  This "stupid" 7DJ8 substitutions are sounding significantly better than the Russian 6922s they replaced.  There is definitely a mid-range magic with this preamp.

I may try a "real" 6922 just for giggles and grins and post the results.  I'm still looking for more volume and a way to feed my subs, so I've made up my mind to get a new preamp.

[ACHiPo]

Question, ACHiPo, are you using the PSE with the same amplifier you used with before putting it into retirement?  Same speakers?

The preamp is driving the same AtmaSphere M60s via balanced interconnects.  The interconnects, however, are longer (albeit lower capacitance) than in my previous set up.  Previously I was using 4 m JenaLab balanced ICs, I'm now using 7 m Darwin Truth balanced ICs.

[ACHiPo]

What would people say if there amplifier was damaged by using the wrong tube?
What would they say if there was a fire?
What would they say if somebody was injured because of......

This is not a game. Better save then sorry i guess.

E55,
Please take this in the way it is intended...

From your posts I suspect that English is not your first language, and that perhaps that gets in the way of your meaning.  As Starchild says, it is clear you (and FullRangeMan for that matter) know a lot about tubes, but any wisdom you have to impart gets lost as it is wrapped in inflammatory language.

Regards,
AC

[mlundy57]

Couldn't you use "Y" adapters to split the signal coming from the preamp with one leg going to the sub and the other to the power amp?

Mike

[ACHiPo]

Couldn't you use "Y" adapters to split the signal coming from the preamp with one leg going to the sub and the other to the power amp?

Mike

Mike,
I'll try that.  I think I have some Y-adapters around somewhere.

Thanks,
AC

edit:  I found the xlr-Y adapters, but I'll need to run some balanced cables to my subs (they're on RCAs now)

[ACHiPo]

Does anyone have transconductance curves for the 6922/6DJ8 vs. the 7DJ8 as a function of heater voltage?  It seems with that information it would be pretty easy to figure out what I'm giving up in performance by running the heater voltage below its designed level.