The Amp Garage

You chamfer those holes at some point right? Chamfering hard to reach holes takes me longer than drilling out an entire enclosure sometimes. I need to get one of those little zippy tools for the hard-to-reach holes. I found a pair of bent-nose pliers work as a quick sub if the hole is going to be h...

In the USA it is not about who is right, it is about who has the attorney that can sway the jury. Pilot holes to fully punched and ready to assemble in 1Hr 5 minutes. I figure with drilling pilot holes it takes about 1hr 15 minutes. As I step up in drill size and complete a set of holes I mark throu...

Ian, I have the 6P1P-EVs biased around 13V with an effective cathode resistance near 360 Ohms, 235V screen supply and 290V B+ (10W dissipation). I'll probably increase the cathode resistor value next build and up the screen supply at the same time to get closer to 250V on the screens for linearity, ...

I'd say the most important part to have on a PCB would be the power supply. This is a critical area for safety, and having it on a PCB would give repeated design quality control. One test I recommend is to remove your output tubes, and put a max load in place of them on the B+ and then slowly increa...

You don't need CE unless you are selling in the EU. You don't need CSA unless you are selling in Canada. UL is for safety only and is a good thing to get. They will test for abnormal conditions (shorted components, etc) to verify that the fuse protects the unit from bursting into flames etc. They wi...

Usually the can's just jump off the chassis when I get this out and wave it at them. You can occasionally find them at garage sales for as little as $5. I passed up one this spring that I should have gotten as it was slightly smaller and would have been easier to work with. This thing is heavy. At 3...

Merry Christmas to one and all, from snowy NE Tennessee USA.

If the voltage from the choke input filter is too low, you can add a small cap before the choke to adjust the output. I generally end up with something in the 2-5uF range when dropping voltage like I did in a little SE stereo amp. I had 335V and wanted to drop it to 280 so I used two 2.2uF film caps...

Easiest and cheapest way is to add a resistor between the output of the rectifier and the first cap which feeds the plates. Say you want to drop to the values shown on the schematic. Pd =12W with 15V bias and 240 Ohms you have 62.5mA for two tubes. Call it 315 on the plates => 12/315=38.1mA so you a...

If you shut off one tube in a PP pair, you may saturate your output transformer.

Worst case you may end up burning up the remaining tube, transformer, power transformer, etc.

Not a good idea. You need to keep the transformer DC bias very low.

Near as I can tell, most of their tubes were 6.3V heater supply.

Klausmobile has a really good list of tubes and most are 6.3V.

http://klausmobile.narod.ru/td/list_e.htm

Fantastic!

I hear ya! ...snip... I just don't build in enough volume to justify spending a bunch on a run of custom PTs- I wish I had a good solution :? Contact EDCOR, for a $40 setup charge they will make what you want. Friendly folks, good prices, and great quality. I stick 2.5R NTC thermistors in series wi...

Around here (NE TN) it varies a lot with location. Some homes are on common transformers and if multiple heat pumps kick in at once during peak demand, voltage can really drop. I'm the only house on a transformer, off a main three phase line. My voltage is pretty stable and varies from 122 to 128VAC...

Probably the best way to approach the Soviet Tubes is the reverse, give the soviet designation and closest western equivalent. 6N1P - Many claim 6DJ8 but it does not really match closely. Probably ECC81 is closest or 6N7. 6N2P - 12AX7 but 6V filament only 6N3P - 2C51 6N6P - maybe 6FQ7, 6CG7 or 6GU7 ...