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Octal preamp amps

12/30/2004 8:25 PM
Octal preamp amps
Does anyone build them anymore? I have a bunch of 5C5 chasses that I should probably turn into kits since I have parts and a 2x12/1x15 cabinet that fits.  
Seems like slamming a gridleak octal preamp would be kinda fun and create some interesting tones.  
Are 6SJ7's available? Will I have to take out a second mortgage to get decent ones?  
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12/30/2004 8:54 PM
Mark Lavelle

"Are 6SJ7's available? Will I have to take out a second mortgage to get decent ones?"
Hell yes, and hell no!  
They're new (probably really NOS) Russian equivalents, and every other type of tube I've bought from him are at least as good as any current production tubes...
12/30/2004 9:08 PM

Phillips/Sylvania glass 6sj7wgta's are available at for $8 each. They sound great and last years.  
Offer a 12v heater option; 12sj7's are damn near free.  
12/30/2004 9:41 PM
I screwed up....
I meant to say 6SC7, which what what the 5C5 used, but I had 6SJ7 on the brain...  
1/3/2005 5:10 PM

Hey Ted,  
Does this mean you are willing to blow out some of these 5C5 chassis at a discount?  
I bought a 12F150 from you for my modified Allen 5F1 project. So far, it sounds best using my mod of an octal pre in parallel to the mini. I have been running a variety of 6SN7s in this position and they all sound much better than any of the minis in this amp. I picked up a box full of NOS and used 6SN7s on eBay for a song.  
What other dual triode octal pres will work in this configuration? 6SL7?
1/3/2005 5:25 PM

The 6SC7 is a little different creature. Same amplification factor as a 6SL7, but the cathodes of the two sections are internally tied together. They are about 13.00 a piece for metal cans. Glass ones may be hard to find.  
I sure do like the ultra-simple circuit of the 5C5, though.
1/3/2005 6:48 PM
6SC7 v 6SL7
6sc7s can be prone to microphonics, also. Using a 6sl7 and joining the cathodes is a good option. They are also a bit more available and inexpensive.  

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