The Amp Garage

Keep in mind that if you place the bias tap after the standby switch, you'll need to locate the standby switch between the transformer secondary and the input to the main B+ rectifier, rather than the more-common location of in the B+ circuit. If the design uses a center-tapped, two-diode full wave ...

Please be very careful when using grease. If you use a grease that is at all conductive and accidentally bridge the back of the MOSFET to the chassis, something will blow. Hi markr14850, I am curious, has this happened to you personally, or is this something you've heard from someone else? I have n...

Shaun, As to the clear insulator for the MOSFET (these used to be made of mica, back in the day IIRC - probably showing my age here). Anyway, just sandwiching the insulator between the transistor and the chassis will not transfer as much heat as you will get with the use of heat sink compound. Here'...

I am vision impaired, so I have to get within a few inches of the work to see it. Oftentimes, I use a 5x jeweler's loop for soldering, which brings me in even closer. I sit at a low bench (standard folding table), humped over to get close enough. I've gotten to the point where I keep a number of box...

A year ago, I stopped buying anything with the JJ name on it. Microphonic tubes and lousy customer service sent me over the edge. The new Tung-Sol and Mullard reissues from Russia look interesting. I've had the opportunity to try some Mullard 12AX7's in my Tonemaster head, and they sound amazing. I ...

After I posted the link to SoZo's pictures, I sent them an email, asking about their recommendations for voltage / frequency for a burn-in fixture. I also asked if a fixed frequency, or perhaps white or pink noise would be best for break-in. So far, no response from them. I am starting to envision a...

Here is what SoZo have to say about capacitor break-in, including o'scope before and after shots:

http://www.sozoamplification.com/break_in.html

Regards,
Lou

Thanks for the cartoon, Lefty - it gave me the best laugh I've had in a long time!

Lou

Hello Everyone, I won't be so bold as to suggest this could be an error, but I'd appreciate any and all comments on this: I am curious about the voltage across V7 in the SSS #002 schematic. I don't see any reference to tube types in the schematic, so I will assume V7 is either a 12AT7 or a 12AX7 (al...

I am curious about the voltage across V7. I don't see any reference to tube types on the schematic, but I assume it's a 12A_7 variant. As there are references to the tube types on this Odyssey schematic http://ampgarage.com/forum/viewtopic.php?p=219153#219153: What schematic are you referring to? T...

I am curious about the voltage across V7. I don't see any reference to tube types on the schematic, but I assume it's a 12A_7 variant. We have +379V on the anodes and -40.4V on the cathodes for a whopping 419.4V across the tube! Even if this were a 12AU7 or 12AX7, both of which having a max anode vo...

Hi Ckpop,

Presently, you are at 18.72 watts (468 x 0.040). If you divide the measured dissipation (18.72) by the tubes' max power (35 watts) , that will give you the percentage of power dissipation, so:

18.72
-------- = 53.9%
35

Cheers,
Lou

I will look into the voltages at the junctions when I get home but do you think there any chance the ot is bad? If there is not an inordinate amount of distortion, the PT is probably not suspect, except for this: Is the primary impedance of the OT correct for the build? I would expect to get about ...

13.6V on all the control grids (pin 2) doesn't make sense to me either, the junction of R17 and R18 are tied to GND....... this is so annoying to me, these are the things that drives me crazy. I'm probably just being silly (or suspicious) but if you haven't already, maybe you should measure the vol...

Also, 13.6V on all the control grids (pin 2) doesn't make sense to me: these grids should be referenced to GND. Check to make sure the junction of R17 and R18 is really tied to GND.