[felix3650]

Suggest you stay with 12AU7 as they have a lower gain factor...

Wide variety of prices, suggest "Baldwin" branded 12AU7's...some made in Japan, some in USA - all sound great and cheap compared to the coveted European brands...

Can spend a LOT on these...so go slow, be careful...be patient.

Thanks JV! 12AU7 be it then. I remember the Baldwin from our previous conversation
Will a 6922 Genalex Gold Lion sound good? It's quite a popular one.

 

[Monsterzero]

I have the embossed Lorenz C3g on order. Will report back later...

Do you have the Seimens to compare them to? Interested in the differences.

 

[leftside]

Do you have the Seimens to compare them to? Interested in the differences.

Yes I do. Embossed and regular. Though to be honest I haven't heard any difference with the C3g tubes so far in the 300B amp.

 

[leftside]

@2359glenn Can the EL34 be used in the C3g sockets in the 300B amp with an appropriate adapter? I already have the EL11 ready to go.

 

[leftside]

Glenn says this about the 12AT7/12AU7/12AX7 tubes:

"This amp driver circuit is not right for a 12AX7 a 12AU7 or 12AT7 will be OK. No wonder it sounded thin and crappy.
This amp can take so many tubes why a 12AX7?????. A very high impedance tube that should have a plate resistor of at least 100,000 ohms.
A 12AX7 really cannot drive the miller capacitance of the output tubes. In many amps the 12AX7 will drive a 12AU7 or 12AT7 to drive the output tubes."

My favorite 12AT7 tubes in my other amps are the early GEC B309 and GEC A2900. There are many, many different 12AT7 tubes. Brent Jessee provides a good summary:
http://www.audiotubes.com/12at7.htm

My favorite 12AU7 tubes in one of my DACs:
https://www.head-fi.org/threads/2359glenn-studio.600110/page-1454#post-14425291

Here's a nice 12AX7... I have a 1954 that I might sell. Basically given up trying to find another.
https://www.ebay.com/itm/ULTRA-RARE...WELDED-PLATES-SQUARE-GETTER-1953/202505566720

Info that I've learnt from my friend: The Mullard 12AX7's go up a LOT in price depending upon the year. 1953 (rarer than hens teeth), 1954 (as rare as hens teeth), etc to the "relatively" common 1957. Why such the huge difference in prices? Rarity, different construction and sometimes different factories and therefore meant to be a different sound. In 1957 Fisher started using them in their equipment, so much more common. This is what makes tube collecting such a fun rat hole. Even the same brand and same make of tube can be different from one year to the next..... and which is why you might see such big differences in prices of tubes which to most people will seem like the same tube (but they are not...).

And the Gold Lion gold pin new production are good.

 

[2359glenn]

I finally switched the 5pin sockets to 8 pin and switched filament voltage from 2.5 to 6.3. Going from #27s to GEC L63
So the amp is all GEC now the beauty o these tubes they are perfectly quiet. I had a hard time finding quiet 27s.
I went nuts with filtering and run the filaments ob DC just to have noisy tubes.
If you can find a pair of L63s cheep get them they sound great. You will need a dual 6J5 to 6SN7 adapter though.
Pic of the amp had to clean allot of dust of o it as it was buried in the back of a cabinet just had to turn on the switch.
Went crazy building this amp in 2006 all wires carrying audio are DH labs 18 ga 99.999% pure silver. And I used
giant Solan output coupling capacitors. Would never do this today craziness.

 

[JazzVinyl]

I finally switched the 5pin sockets to 8 pin and switched filament voltage from 2.5 to 6.3. Going from #27s to GEC L63
So the amp is all GEC now the beauty o these tubes they are perfectly quiet. I had a hard time finding quiet 27s.
I went nuts with filtering and run the filaments ob DC just to have noisy tubes.
If you can find a pair of L63s cheep get them they sound great. You will need a dual 6J5 to 6SN7 adapter though.
Pic of the amp had to clean allot of dust of o it as it was buried in the back of a cabinet just had to turn on the switch.
Went crazy building this amp in 2006 all wires carrying audio are DH labs 18 ga 99.999% pure silver. And I used
giant Solan output coupling capacitors. Would never do this today craziness.

Sure is beautiful Glenn!!

I bet it sounds as beautiful as it looks!!

Congrats on the conversion!!

 

[JazzVinyl]

I built my 3-way Speakers in 2006 and bought “extreme” caps for the crossovers...

Pretty sure a lot of the benefit of the costly caps...are in my head.

But I have used them a lot, and loved them much...cant believe It has been 12 years since the build....

Sheesh, where does the time go?

 

[JazzVinyl]

Enjoying the original 1973 LP:

 

[2359glenn]

I built my 3-way Speakers in 2006 and bought “extreme” caps for the crossovers...

Pretty sure a lot of the benefit of the costly caps...are in my head.

But I have used them a lot, and loved them much...cant believe It has been 12 years since the build....

Sheesh, where does the time go?

Good capacitors usually make a difference. But silver wire I must have been nuts at the time. Really wire makes little or no difference.
How would I know make 2 amps and A-B them?

 

[mordy]

Good capacitors usually make a difference. But silver wire I must have been nuts at the time. Really wire makes little or no difference.
How would I know make 2 amps and A-B them?

Hi Glenn,
Is this the amp that runs on 240V DC?

 

[2359glenn]

No but the DC B+ voltage is 250 to the output tubes 240 to the drivers.

 

[lukeap69]

These are the adapters Deyan built for me. He will be shipping these today.

 

[mordy]

These are the adapters Deyan built for me. He will be shipping these today.

I have the same ones coming - sitting in Customs right now. I am sure that you realize that they are made in Siemens Yellow lol.

 

[lukeap69]

I have the same ones coming - sitting in Customs right now.

How fast is the shipping?