The Amp Garage

So if the voltages are all pretty close, why go from a 4.7k/390 to a 8.2k/1k? Perhaps voltage isn't the only issue?

#3 Double ended Pentode "output stage distortion" as in large amps, including the Bassman..... Push pull operation cancels even harmonic distortion generated in the output stage, so it can contribute only odd harmonics, principally third. Noticeable bias shift when driven hard can cause compression...

For me; the 220k/150k plate resistor is more gainy than the 100k/100k plate resistor. Yes...assuming they're set up properly. And, as a rule, there is less linear distortion with the higher plate values...BUT, what little distortion is there tends to be more third-order. The lower plate values give...

Southbay Ampworks wrote:With the Fenders it was all over the amp...

I assume you mean "map".

"WHY ALUMINIUM CHASSIS?"

*BURP* WHY NOT!!!?

The Peavey PT has a 56V tap for bias. If I run a voltage doubler from that tap I might come close, according to the Duncan PSU designer I'll get 130V. I CAN get a - voltage from a doubler right? Close, but no cigar. It has to be at least 150 when using Dumbles SSS circuit, or you might not have eno...

The Peavey PT has a 56V tap for bias. If I run a voltage doubler from that tap I might come close, according to the Duncan PSU designer I'll get 130V. I CAN get a - voltage from a doubler right? Close, but no cigar. It has to be at least 150 when using Dumbles SSS circuit, or you might not have eno...

toneslinger wrote:Eric sold that amp back to bruton along time ago
I gave my word id never repeat the price and I wont.

Fair enough...but can you say when EJ originally bought the amp to begin with and what speakers he was using?

BTW, welcome to the board!

Some SSS seem to be using the 12BH7 ampeg section. Yes, and I saw an odd post stating that the bias supply needs to be -300VDC. I don't understand that. 150 volts will do. You don't need 300. Old Music Man trannies put out 650 volts B+...the SSS runs at around 500 volts at the plates, so all you ne...

David...you've got the Altec story correct, as far as you went. As for the sticker shock, colbalt (a component in alnico magnets) has shot up in price just this past week. A speaker I got new last week for $189 went to $269 overnight...literally. So $340 for a speaker that uses a large alnico magnet...

Lot's of discussion recently on signal caps of the film variety, but I don't remember seeing anything on the lower value caps as used for Treble and Brightness, etc. It seems the standard is ceramic disc, but I was wondering if anybody had tried silver mica and had an opinion as to what it did to th...

I personally think the high plates sound better on both clean and the OD stages. We think alike, in some ways...but here we differ. The higher the plate resistance in these kinds of gain stages, the lower the overall distortion...BUT...what distortion remains is more third-order than second-order. ...

The Altec 417 is rated for 75W. This would be a 50W amp so it should be safe, yes? The Altec 417 is a 100 watt speaker. Best be careful...a 417 is not always a 417. That is, there was more than one model. When the Boogie was originally created, the models were 417-8A, -8B, then -8C. The first two h...

Before I knew better, I bought a bunch of P715s...20 or so in typical Fender/Marshall values. Any amps they are good for? I don't want to sell them to an unsuspecting mark, I want to use them or move them where they're the right part. You can always use such caps for non-tonal purposes...several pl...

Might also look at the 192P series [polyester] these are round, they discontinued them in 2008. But this place used to stock them, and have them on hand. They are replaced now with 470p.. which are a round "orange " type. http://www.elecsupp.com/other.php3 These caps (192P) are mylar wound in secti...