[SonicTrance]

Remember the plate voltage for the 6SL7 should be lower than 200V which is not the case with 6SN7

Typical operation for 6SL7 is 250V according to datasheet. Max rating is 300V.

 

[L0rdGwyn]

One bad thing it would allow you to set the plate current way to high for the tube.
Then I thought a selector switch with resistors that clicks to the wright tube. But you guys use so many different tubes this would be impossible.
And then a tube might sound better with a less then optimal setting that would make the pot better.
Have to think about this more.

I'm just imagining a scenario where a child or mortal enemy fiddles with your biasing knob when you step away for a moment and you forget to recheck it. Is there such thing as a locking potentiometer?

Might sacrifice some usability for better sound quality, but that has never stopped audiophiles before

 

[attmci]

Theoretically, tubes biased at their perfect operating points should sound better. But perhaps this is not always true?

For example, an ECC32 installed in a 6SN7 socket is not biased properly. And yet, some claim it sounds better than any properly biased 6SN7.

So maybe, just maybe, the reason the ECC32 sounds so great is exactly because it is biased incorrectly? Or maybe, just maybe, if it was biased correctly it would sound even better?

Being able to adjust the bias would allow us to determine if the perfect bias actually does sound better in each case.

The reason we prefer a tube amp to a SS amp is due to the nice distortion.

BTW, eBay begun to collect tax in a number of states..... including mine.

 

[2359glenn]

I'm just imagining a scenario where a child or mortal enemy fiddles with your biasing knob when you step away for a moment and you forget to recheck it. Is there such thing as a locking potentiometer?

Might sacrifice some usability for better sound quality, but that has never stopped audiophiles before

It burns up your precious tube.
Your right not a good idea.

 

[UntilThen]

One of the best drivers for the ECBA is the ECC35 even thought the amp uses 6SN7 drivers.

For me, this is also true with GOTL.

 

[mordy]

Mordy if I remember well the 7F7 and 7AF7 are similar in characters to the 6SN7 not the 6SL7
Need to check the data sheet to be sure

Hi rosgr63,
This is what the Radiomuseum says about the 7F7:
7F7 = VT-189 = CV893
Similar Tubes
Heater different:
14F7
Other base:
6SL7GT

And this is what it says about the 7AF7:
7AF7
Similar Tubes
Heater different:
14AF7
Predecessor Tubes 6AH7GT
Successor Tubes 12AU7

 

[UntilThen]

My top ten drivers in no order of merit:-

ECC35
ECC33
ECC31
Sylvania 6sn7w metal base
Tung Sol 12SL7GT bgrp
RCA 5691
GEC B36
c3g
EL11
EL3N

I just loaded the 12SL7GT without changing the voltage to 12.6.

2 mins later I realise that and change it. This is waking up at 7:30am.

 

[Phantaminum]

Hi rosgr63,
This is what the Radiomuseum says about the 7F7:
7F7 = VT-189 = CV893
Similar Tubes
Heater different:
14F7
Other base:
6SL7GT

And this is what it says about the 7AF7:
7AF7
Similar Tubes
Heater different:
14AF7
Predecessor Tubes 6AH7GT
Successor Tubes 12AU7

Glenn made a point earlier in this thread about the 7AF7/14AF7 tubes. They do turn microphonic or become noisy. Out of all three that I have, they started off fine and then static or a very significant background noise kicked developed. 7N7s are good tubes though.

 

[mordy]

My top ten drivers in no order of merit:-

ECC35
ECC33
ECC31
Sylvania 6sn7w metal base
Tung Sol 12SL7GT bgrp
RCA 5691
GEC B36
c3g
EL11
EL3N

I just loaded the 12SL7GT without changing the voltage to 12.6.

2 mins later I realise that and change it. This is waking up at 7:30am.

Hi UT,
I assume that you use all the above with 6x6BX7?
Re the voltage switch nothing will happen if you put in a regular tube with the wrong voltage applied. BUT, if you use a tube with an adapter with the amp set at the wrong voltage, you may risk damaging the tube. In other words, if you forgot and left the voltage switch on 12V and put in a 6V 6F8G that needs an adapter, it might get damaged.

 

[UntilThen]

I'm currently having an amp built by a local builder, and I've opted for 3 different socket types for drivers: C3g (2), 6J5 (2) and a 6SN7 (1). There is also a selector knob on the front of the amp to select which drivers to use, and also the 6SN7 socket can take 12SN7, 6SL7 and 12SL7. All 6 options are selected via the selector knob. These are my chosen selections as I have a lot of these tubes, but I'm sure the selection choice could be endless... perhaps others would prefer a EL32, EL3N, selector, etc.

This is nice. With the exception of the 6J5 tube, I've sampled all the others in the OTL amp.

If I had to do it again, it would still be the amp that I have. The only options I had were the Gold Point 37 steps attenuator and the 5998 boost switch. The attenuator is nice and I have not regretted spending an extra $300 for it.

But I might consider a tube rectifier just because I'm curious about what sound changes that would bring.

 

[UntilThen]

I assume that you use all the above with 6x6BX7?

Yes all with the 6BX7 or 6BL7 tubes.

The only other power tubes that I brought along are:-

Tung Sol 5998
GEC 6080
Cetron 6336b

I should be happy with these through the cold winter here.

 

[mordy]

Glenn made a point earlier in this thread about the 7AF7/14AF7 tubes. They do turn microphonic or become noisy. Out of all three that I have, they started off fine and then static or a very significant background noise kicked developed. 7N7s are good tubes though.

Speaking about 7N7 tubes, does anybody have experience with this WW2 version in the GOTL?

 

[mordy]

Yes all with the 6BX7 or 6BL7 tubes.

The only other power tubes that I brought along are:-

Tung Sol 5998
GEC 6080
Cetron 6336b

I should be happy with these through the cold winter here.

I am using two pairs together of 6080 tubes by Bendix and RCA to battle the A/C.

 

[leftside]

I'm just imagining a scenario where a child or mortal enemy fiddles with your biasing knob when you step away for a moment and you forget to recheck it. Is there such thing as a locking potentiometer?

To adjust the bias on the 300B amp you need a screwdriver, or a strong finger nail.

 

[Zachik]

Add the wonderful 6SU7

Are these a replacement (i.e. no adapter) for 6SN7 ?
What is the difference (so I can add a note)? Different gain?