Tube Amp Archive

Hello. I don't post here too often but this was brought to my attention. That is actually my blog post. The wires underneath the vero had been insulated with teflon sleeve, but that insulation point you made was a concern of mine too. Eventually that board was replaced with an FR4 board that had 2 t...

Many thanks guys. You are all stars.

Cheers. Using the scope method, it seems the difference is only fairly slight compared to some. Anyway, It's a cool little test!

Hello, thought I'd ask this question here. I just got a couple of 6PS caps and having read Randall Aiken's article about foil orientation, http://aikenamps.com/OutsideFoil.htm, I had a go at using my scope to find the outer foil. Now, I could see an amplitude difference in induced frequency when swa...

The VHT does indeed use a cathodyne. In the 60watt 2xKT88 there are no buffers, but in the 120watt version I believe there are cathode followers between the PI and the KT88's. I also think the Pitbull uses a cathodyne too, but has no followers between the PI and EL34's. I might be wrong about that t...

OK guys. I did some experimenting while I'm waiting on some better pots/cable. [img:800:600]http://img.photobucket.com/albums/v174/xtattybobx/IMG-20120229-00634.jpg[/img] Here is the first thing I did. Flat on the chassis. It gets messy around the PI and its driver stage since there isn't a lot of s...

If that was my amp, I might consider routing the shielded from the pots under the board and looping back around on top of the board. Just a thought -- and it may not be practical, as I'm not sure what is under the board in the way of transformer wires entering the chassis. Good luck with this. I th...

You shouldn't need shielded wire from the board to sockets v1-v4. Just use good quality and properly rated for the voltage. I can't recall ever using shielded wire for what amounts to something between 2" and 5" of wire in that kind of location. Grids are the most sensitive. I'd do those first and ...

cool. I can have a go at putting the plate and cathode wires on the bottom of the chassis, but I don't have much left of the shielded wire I use. Is it worth trying the plate and cathode wires first, then maybe looking at the shielded grid ones at a later date? I actually bolted this amp back into t...

The OT wires are running along the floor of the chassis and up to the switch. It's hard to make out in that photo. The OT primary goes the same way, along the floor. The OT secondary wires are slightly twisted together with a tie wrap on, there is no tie wrap on the primary. There is a tie wrap on t...

Thank you so much for the kind words. It isn't perfect but it's my best so far. I think I found the hum! I added another shielded wire to the second grid on V2. That took a lot of the hum out. I'm going to replace the original shielded wire on V2 as well, and get the shield as close as I can to the ...

I've been working on a build. That's high gain again. It sounds good but suffers from some hum. It's in an old Laney AOR series II chassis and I'm using an in-line filtered IEC. 6A. I've tried pulling tubes in order and poking things around. I've gone for star/node ground as per merlins book.... Sta...

sorry! you're right. they are two different windings, that is a mistake how i have drawn it. The advantage to doing it that way for me personally is I can get the board layout to work a bit easier. Otherwise I'd do it exactly the way you suggest, which was my original plan. I just wanted to check I ...

I attached a sketch on what I mean.
I'm sure there is no real advantage to doing it like that right? But is it a bad idea?

My post might not have been clear. its two different 6.3V winds on the PT. one is higher power and im using it for four power tubes and two 12AX7's. There is easily enough current to run KT88's and one of the triode stages included in this is a cathode follower. The other 6.3V tap has less current a...