The Amp Garage

Here is Randall Aiken's Tech info page..On the same site he promotes his amps!!..Very 8).. If he wrote a book It would IMO be a great read! http://www.aikenamps.com/index.php/tech-info Tony Thanks for the nice comments, Tony! I appreciate it! I have been threatening to write a book for many years, ...

If you just want to lower the screen voltage without the degenerative feedback associated with the variable voltage drop across a large screen dropping resistor, or the power wasted in a voltage divider and the associated large filtering requirements, simply use a zener diode of the appropriate volt...

...I found some of the easiest to follow explanations and guidelines are from Randal Aiken. Amazing that this stuff is free to make use of... rj Well, I do accept contributions in the form of cash, check, money order, hot Asian mail-order brides, etc. Actually, all kidding aside, thanks for the nic...

I wonder what it uses for it's output. I've stopped following high power transistor technology years ago. I have a couple old SS guitar amps, one being a Peavey Century head that is 100 watts that uses the old power transistors. Still works great after all these years. So I wonder if he is using di...

Hi Everyone, I hope I'm not intruding on the discussion but I wanted to throw HMC Electronics' hat into the ring on where to get soldering products. We sell everything you need to get set up with soldering. We are full Kester Hakko and Weller distributors and we sell many other major brands as well...

Doesn't Rohs only apply in Europe and on computer displays in California? Or for manufacturers wanting to sell to EU countries... And don't worry, our bureaucrats are frothing at the mouth to inflict similar restrictions on us very soon. In fact, the EPA just tried to ban lead in bullets and fishin...

I use the Dremel tool with a cutting wheel. Fast and easy.

RA

I needed some super fine-pitch (0.020) RoHS no-lead RA solder in a hurry the other day, and since I was placing a Digikey order for everything else and needed one-day shippng, I ended up having to pay a whopping $105 for a pound of the stuff. Sheesh! http://search.digikey.com/scripts/DkSearch/dksus....

rooster wrote:Well, been away and see that Randall A. stopped by for a visit. That was nice, thanks! And, raiken, I wanted to say that I appreciate your site and the archival database you have created. It is a big help on certain occasions.

Why, thank you! I'm glad the info was of some use to you.

RA

Negative feedback will reduce distortion in the stage that the feedback is wrapped around. Basically, it tries to make the output "look" like the input, so if any harmonic distortion (odd or even) is added by the stage, the feedback will try to remove it. Negative voltage feedback does the following...

BBTW, in troubleshooting the JVM, I found a blown HT fuse (internal, 1A 5mm pain-in-the-butt), an open 1 ohm cathode resistor with no sign of burning - the guy was running on one side of the push-pull pair only! After I fixed that, I also found a pin on the PI tube that had no solder on it at all - ...

It just so happens I have a JVM 100W amp in here that a friend asked me to repair. It has 500V on standby, 480V on the plates at idle, and sags to...get this...408V at full clip! The screens sag from 466V at idle to 340V at full clip! Compare this to your 30V sag at full clip... I am measuring right...

Randall, yes I'm use to measure voltage drop over the 1k screen resistors, at least if I run a hot bias. the early 100watters with the 1202-84 OT run the screens hard btw. Z=4k and b+ is originally 560v. screen voltage is 559v. this is very hard on the kt66s Yes, running KT-66's at a 560V and 4K im...

On a related topic, you also have to consider screen grid dissipation. When running tubes at very high voltages, you will likely see the screens glowing brightly in time with the music. This is a sign that they are probably running too hot - you can tell by the brightness/color of the glow. If they ...

Could you get away with using a greater reflected load to address the high voltage issue, as Roe has suggested, "I will try running a 16ohms load into the 8 ohms secondary. ", or is it wiser to use, as you have all ready stated, a different opt? A transformer doesn't have an impedance, it merely re...