More Info on Sonic I

[Bill Matthews]

The power transformer reads P135, the output transformer reads Dynaco 470 A, according to the schematic on this site the amp is supposed to have a feedback loop, it does not.  The 270pf cap that is supposed to go between the ground of the power tube cathodes and the center tap is also not there.  Just a couple of last minute things to ponder.. No one has ever touched the insides of this amp, that I can tell, and I don't know if all of the Sonics are this way, but all mine says on the faceplate is Sonic I.. Is this the way all of them are, or do some of them say Sonic I-40?  Thanks again...Bill

[Mark Ratcliffe]

Hi Bill, Long time, How are you? Looks like you got a good project to work on.

The Sorado is going strong. Wish I could find a 2 15 bottom.

Have you ever used the JJ tubes from Euro tubes? And have you ever used their services? The guy looks like quite a collector but I always like to get a second opinion. Take Care

Mark Ratcliffe

[made by hand]

hi Bill...ok...your sunn sonic1 is the name of the amp...which was sold with or coupled a single 1 15 inch speaker cab that housed a jbl  d 130 speaker......the sonic 140 was sold as an well..option or choice single 15 inch cab with the d-140 in it...the head never said ...sonic 140.......it said ...sonic 1  ......if you wanted to split hairs....you could say it was the sonic 130.....see......the head never knew what it was plugged in to...the cab choice was up to the buyer at the time....it came down to how much money he had in his pocket....your amp is still a slick little amp.....you own a piece of history....hold on to it...any money you put into it is worth it....smiles...Bob from mass.

[basiklybass]

My 200S is also missing that 270pf cap on the output circuit. I tried adding it and got some high freq squealing. Took it right back out.

I just changed my 12AX7 from an EH to a JJ...much nicer sound IMHO. I am going to buy some JJ KT88's when I get back to work.