[digger945]

Is that a gold anodized Par-metal case? I have two of those for the Dynamite. I think it looks great, much neater than mine. Really like those 2 big Panasonics.

Looks like there is a trace between the Ref and H- on the pcb.

 

[Coreyk78]

Yeah, its one of the gold Par-metal cases, I actually had ordered the clear anodize over the phone, but it came gold and I thought it looked cool so I decided to roll with it.

And the reason I'm worried about the heater supply thing, is I'm thinking that if it isn't raised above ground that I'm probably exceeding the heater to plate voltage difference or whatever, so that could have maybe been causing some of the weirdness I heard last night.

 

[digger945]

Well the heaters are on a seperate circuit on the pcb from PS, but maybe the two are touching somewhere on the pcb.
I wanted to ask how you have your attenuator wired, and to what do you connect the ground?

 

[Coreyk78]

The pot is one of the other things I may have an issue with, I have 6 pairs of rca inputs and I'm using a 2 pole 6 pos grayhill switch to select inputs, and all the rca grounds are tied together but seperated for left and right, then connected to the input grounds on the Aikido PCB.

The left and right channel outs of the grayhill switch are connected to the pot and then to the inputs on the PCB. I didn't know what to do with the pot grounds though, so I wired them together to chassis ground, which may be wrong, idk. I'll probably try bypassing the selector and pot as an experiment.

 

[digger945]

I remember trying to just wire the negative input from the 0404 directly to my cans and just use the positive through the amp, sounded awful so I hooked the input ground back up to the amp pcb. The 0404 has an attenuator built in and I use that for volume. You may have a problem here if the input ground isn't making it all the way to the pcb or something, maybe.

 

[Coreyk78]

well the grounds are connected straight from the rca sockets to the pcb, so as long as the pot doesn't need to be grounded to the pcb then it should be ok

 

[digger945]

Yea that sounds ok, I don't think I would try grounding the pot to the pcb either.

EDIT: Maybe as a last resort it wouldn't hurt to try grounding the pot to the pcb Corey, just to see if it helps any.
Still don't know what might me giving you problems on only one channel though.

 

[Coreyk78]

Well, I still had some hum and distortion in both channels, just the left had much, much less hum.

 

[digger945]

Progress. Did you bypass something or cut and rewire?

 

[Coreyk78]

I bypassed the pot, no change, so that wasn't the problem.

One thing I was able to try though, since the UPS guy got here. I'm gathering parts for a Tubelab.com Simple SE amp right now, and my choke came in today. A rather large Hammond 193L with 5H @ 300mA. I removed the tiny choke and temped the big one in, hum is gone in both channels, but it still has a prominent background hiss, and there is a lot of crackling in right channel. I'm gonna check some more stuff out. I think I may have a cold joint at the right input.

 

[digger945]

Ah yes, I had the exact same problem on a millet Hybrid once. Reflowed some ground joints and it cleared right up.

 

[Coreyk78]

reflowed a few joints and tried swapping out the right channel tubes and it cleaned up quite a bit, I'm still getting some bass distortion on the right channel, not sure why. Maybe fixing the heater bias could change that if the tubes are running outside there parameters right now.

edit- actually I'd say there is almost equal bass distortion on both channels.

another edit- I'm wondering about how I have the heater supply wired. The transformer I got is 12.6vct but I just connected the outside taps and left the center tap disconnected since my H-PS-1 was already built for a non CT transformer. I could remove a couple diodes and ceramic caps and connect the transformer CT in a full wave CT config. Don't know if that would make any possible difference.
I've tried pulling up some threads over on diyaudio.com about how to float the heater supply and they are talking about somehow referencing the center tap of the heater transformer to B+ with a voltage divider to float the heater supply. However, I have no idea what that means or how to go about doing it.

 

[looser101]

Glad to see progress is being made.

Look here for a psu schematic. My choke was that big silver thing on the left, in the pic.

 

[Coreyk78]

Quote:

Originally Posted by looser101 /img/forum/go_quote.gif Glad to see progress is being made. Look here for a psu schematic. My choke was that big silver thing on the left, in the pic.

I'm assuming that psu schematic is what you used for your original supply. I just ordered the exact same choke or at least the one that matches the specs in the schematic. What value did you use for R? I suppose that might vary somewhat depending on current draw, but I'm having trouble modeling it in PSUD2 and I don't want to have to order a whole stock of 10W resistors, hehe

Also how was your heater supply set up? Did you float it above ground?

I'm not going to try and work on it more tonight however, since I'm now on beer 3 and losing concentration...

 

[looser101]

Quote:

Originally Posted by Coreyk78 /img/forum/go_quote.gif I'm assuming that psu schematic is what you used for your original supply. I just ordered the exact same choke or at least the one that matches the specs in the schematic. What value did you use for R? I suppose that might vary somewhat depending on current draw, but I'm having trouble modeling it in PSUD2 and I don't want to have to order a whole stock of 10W resistors, hehe Also how was your heater supply set up? Did you float it above ground? I'm not going to try and work on it more tonight however, since I'm now on beer 3 and losing concentration...

10ohms 10W worked well in my setup. Maybe you can get 2 or 3 and add or subtract depending on what you need.

I never elevated my original heater circuit. I just connected a .1uF cap from H+ to ground. If you want to elevate it, the circuit is in the manual.

Add the two resistors and the cap to the output of your B+ psu, then run a wire to the ref connection the H-PS-1.