[gibosi]

I use adapters all the time. For example, four 6BX7 in place of two 6AS7, one ECC40 in place of one 6SN7 and one 1861 rectifier (a 4-pin version of the AZ4) in place of one 5U4G. To my ears, it sounds great.
 
But of course, YMMV...
 

 

[hypnos1]

  I use adapters all the time. For example, four 6BX7 in place of two 6AS7, one ECC40 in place of one 6SN7 and one 1861 rectifier (a 4-pin version of the AZ4) in place of one 5U4G. To my ears, it sounds great.
 
But of course, YMMV...
 

 
Call me pessimist/cynic but I firmly suspect you could be living on borrowed time gibosi...or, rather, your lovely amp LOL! If Glenn had made all those adapters - especially the multiples - I personally would feel much happier...

...I just hope your luck holds out...

...
 
As for sound, I personally have found quite noticeable differences between various wires - and combinations thereof - when making my own adapters...eg. just pure silver wire or in combination with single-crystal copper wire and/or 24K gold wire...

 

[gibosi]

Making pin-adapters is about as simple as it gets. For example, a small piece of wire is used to reroute the tube's pin 8 to pin 4 in the octal socket. Again this is not rocket science. Further, Glenn has never expressed any reservations to me about my use of these adapters. In fact, he explicitly recommended the one I am using for the rectifier. So no worries. I sleep very well at night, thank you very much. lol.
 
And I will leave it to others to debate the "noticeable differences" that can be attributed to 1/2 inch lengths of various wires...

 

[hypnos1]

  Making pin-adapters is about as simple as it gets. For example, a small piece of wire is used to reroute the tube's pin 8 to pin 4 in the octal socket. Again this is not rocket science. Further, Glenn has never expressed any reservations to me about my use of these adapters. In fact, he explicitly recommended the one I am using for the rectifier. So no worries. I sleep very well at night, thank you very much. lol.
 
And I will leave it to others to debate the "noticeable differences" that can be attributed to 1/2 inch lengths of various wires...

 
Hmmm...have you ever tried making ones where many of the wires have to travel in very convoluted, crisscrossing directions...plus the possible detrimental effect on connections due to the heat generated when sealing with 2-part epoxy resins? I can assure you this is NOT always "as simple as it gets"!!...try it some time...

 
As a result, even the pro adapter makers sometimes give up on the wire method and then resort to pure PCB construction...then you have the debate of wire vs PCB lol! There's more to adapters than meets the eye...

 

[jhljhl]

Hmmm...have you ever tried making ones where many of the wires have to travel in very convoluted, crisscrossing directions...plus the possible detrimental effect on connections due to the heat generated when sealing with 2-part epoxy resins? I can assure you this is NOT always "as simple as it gets"!!...try it some time...:wink_face:

As a result, even the pro adapter makers sometimes give up on the wire method and then resort to pure PCB construction...then you have the debate of wire vs PCB lol! There's more to adapters than meets the eye...

Quality, quantity, safety and sound; four factors in tube adapter consideration.

 

[hypnos1]

Quality, quantity, safety and sound; four factors in tube adapter consideration.

 
Yes indeed, jhljhl....could probably come up with even more lol!

...

 

[Jozurr]

SQ wise gibosi, which tubes do you consider best sounding, regardless of type? they dont have to be 6SN7 necessarily. Im thinking if there are better tubes than for example 6SN7W that I can roll into my amp using adapters.

 

[gibosi]

Of course, some adapters are more difficult to build than others. And of course, some practitioners are more skillful than others. But again, this is not rocket science. People have been building adapters for at least 75 years. The basic technology is very well understood. And in most cases it really is as simple as connecting pin X on the tube to pin Y in the socket.
 
In the end, I have had very good luck using a large number of adapters purchased from multiple eBay vendors. And based on my experience, if someone wants to run a 396A in their 6SN7 amp, my recommendation is simply buy a cheap adapter and do it.
 
Cheers

 

[Frihed89]

  Making pin-adapters is about as simple as it gets. For example, a small piece of wire is used to reroute the tube's pin 8 to pin 4 in the octal socket. Again this is not rocket science. Further, Glenn has never expressed any reservations to me about my use of these adapters. In fact, he explicitly recommended the one I am using for the rectifier. So no worries. I sleep very well at night, thank you very much. lol.
 
And I will leave it to others to debate the "noticeable differences" that can be attributed to 1/2 inch lengths of various wires...

I stay away from adapters for tubes that don't have the exact same filament current as the 6SN7GT, even if they have a resistor inside.  In fact, I only use electrical equivalents with pin adapters.

 

[jhljhl]

  I stay away from adapters for tubes that don't have the exact same filament current as the 6SN7GT, even if they have a resistor inside.  In fact, I only use electrical equivalents with pin adapters.

 
Such as?

 

[gibosi]

  I stay away from adapters for tubes that don't have the exact same filament current as the 6SN7GT, even if they have a resistor inside.  In fact, I only use electrical equivalents with pin adapters.

 
Resistors? Why would they be necessary?
 
And what about tubes that draw a different filament current than a 6SN7GT, but don't need adapters? Such as the ECC32?

 

[2359glenn]

 

  I stay away from adapters for tubes that don't have the exact same filament current as the 6SN7GT, even if they have a resistor inside.  In fact, I only use electrical equivalents with pin adapters.

 
Resistors? Why would they be necessary?
 
And what about tubes that draw a different filament current than a 6SN7GT, but don't need adapters? Such as the ECC32?

The transformer in your amp is hefty enough to handle most anything you can through at it.

 

[gibosi]

  The transformer in your amp is hefty enough to handle most anything you can through at it.

 
Yes, Glenn, I know this.
As long as I do not exceed the capacity of the transformer, the heater current draw makes absolutely no difference.
 
I'm just trying to understand Frihed89's thinking on this....

 

[Frihed89]

   
Yes, Glenn, I know this.
As long as I do not exceed the capacity of the transformer, the heater current draw makes absolutely no difference.
 
I'm just trying to understand Frihed89's thinking on this....

This is correct.  But I wrote too hastily.  A competent builder can make adapters that will have the correct pin wiring and be safe, and then the only technical operation question relates realtes to the ability of the power supply to meet meet the demands of the tube. But what about the driver bias, gain, linearity, etc.? The part i didn't put in was about the characteristics of the driver circuit of non-electrical equivalents vs those of the 6SN7GT and it's electrical equivalents.  For example, to get the most out of the 5687 in a 6SN7GT driver circuit, you may find it necessary to increase the bias or increase the plate current (or both).  Linearity is not a problem.  But it can be with the 12AU7 which is not particularly linear and many believe it is a poor substitute for the 6SN7GT (and many don't).   I had the very fortunate experience to own an MPX3 (+ something) that only needed some bleeder resistors on the PS caps and elimination of the high plate voltage switch to make it safe.  I had almost all of the adapters made by SP.  The amp sounded best to me with all 6SN7GTs or their exact electrical equivalents.  Of the 12XX7 tubes, the worst was the 12AU7, and the best was probably the 12BH7.  The 12AX7 was a no-go, along with the 5751.  The 12AT7 worked as did a number of the tubes in between the gain of the 12AT7 and 12AX7, but the gain was too high for me.
 
Builders who make amps that work with adapters probably know what they are doing.  The BottleHead Crack is probably a good example of this and so was the So was the MPX3 with the right power supply and rectifier diodes (but SP is a special example due to some bad designs and/or wrong components of other products).  The main reason, I only use the 6SN7GT, and the 7N7, 6F8G to replace it in 2 of my power amps and 1 preamp has to do with the fact that these pieces were designed around a 6SN7GT front end (and a specific output or follower tube) and I have lots of these tubes, bought years ago.  This also has a lot to do with my sonic preferences.

 

[gibosi]

Yes, driver bias, gain, linearity, and so forth are a concern when rolling. However, in my experience tubes typically seem to be very forgiving of these differences. And therefore, my philosophy is to try them and let my ears decide.
 
For example, the correct cathode resistance for an ECC32 is about half that of the 6SN7. However, many, myself included, find the ECC32 to be as good, or better, than most 6SN7 when installed in a 6SN7 circuit. Maybe it would sound better if the circuity was modified for an ECC32? I don't know... Maybe it sounds better precisely BECAUSE the bias is incorrect? Again, I do not know...
 
I have two rules. One, I make sure not to exceed the transformer's capacity for heater current. And two, I avoid tubes with an amplification factor above 40 which means I do not roll 6SL7, 12AT7, 5751, 12AX7 and similar.
 
Within these constraints, I have achieved excellent results rolling 396A, ECC40, ECC88, ECC804, E182CC, E80CC, 5687, 6463, 6AH7 and even a pair of #76 triodes.
 
But of course, my ears and my gear. YMMV.