Tube Amp Archive

John Mergili built the cabinet I finished in the above photo. Excellent work at a reasonable price.

The shellac can be sprayed also. Thin it out pretty far with alcohol and apply light coats to sneak up on the final tone. Have fun and good luck!

Amber and clear shellac mixed about 50-50, with satin water-based conversion varnish topcoat.
[img854]http://s19.postimg.org/nc6hez2ab/5_E3.jpg[/img]

martin manning wrote:I don't think the 16-ohm tap was used until I suggested miss-matching the load to get a 4K primary impedance for 6L6's. If that is the case then it wouldn't have had any effect.

That's correct. The tube failed using the 8-ohm tap before the 16-ohm was tried.

Thanks, Lou...btw, should I be concerned about the high heater voltage? It's down slightly (3.4) with the new tubes in place.

Got it working tonight! I contacted Heyboer asking about the possibility of OT damage, and they informed me today that the wiring diagram I was supplied with had the brown and green wires reversed, so at the 16 ohm setting it was bucking the other windings! Put in the new KT66s I got today and every...

Checked again and V5 drops 2.5v from pin 6 to pin 4. In checking the impedance switch wiring, I noticed that I was getting .5 ohm or less between each of the 3 switch terminals and ground. Here's the wiring diagram I'm working from: [img:1190:1054]http://s19.postimg.org/sgdi6k2qb/HTS_7073_RS_Deluxe_...

I've got EL34s in now, impedance selector at 16, and not blowing fuses. [img:667:162]http://s19.postimg.org/p0ldx05hv/voltages.png[/img] These numbers seem pretty good to me. However, at 16 ohms into an 8 ohm speaker, I get an extremely fuzzy and low amplitude signal out. I biased to 38mA, which is ...

I was getting 420-422 on the plates and screens of both without the power tubes in place. Primary impedance is 8k.

I think you're right...power tube. I'm getting anything from 200 ohms to a dead short between pins 2 and 3 on one tube depending on how I tilt it.

First time through, I checked all the voltages, but didn't check bias current. Bias voltage seemed fine, so I left it all the way cold and couldn't resist giving it a try. I will get some more fuses later, and recheck the voltages. As I only have the one pair of KT66s, would subbing 6L6s or EL34s po...

I got this completed today, and it worked great for 10 minutes! I started off at lower volumes, and then I turned it up to about 7, turned up the guitar vol, and it suddenly went dead with a blown HV fuse. I went back, removed all the tubes, re-checked my wiring, which seems to be fine. I went back ...