amplifiednation wrote:Looks good Steve! You are going to have a working amp in no time!
I used a 50w bassman PT from mojo for mine and it worked great. It didn't fit the CE chassis mounts, but I think that is because its drilled for a 100w PT.
PAB looks good, so you decided to use a different wiring scheme?
PAB is wired as per #124.
The wiring looks slightly different as I use relay PCBs that I fabbed myself, not the jborders ones. My contact holes are in a different order.
I am thinking about doing another batch of boards, including precision power supplies, relay boards, fet boards, and rectifier pcbs.
After i finish up the layouts, I may post a thread to gauge interest from other folks.
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Last night I got my components placed on the preamp board. I soldered any connections that won't have off-board wires attached.
Hopefully I can get wires attached later today.
I think on future boards I am going to machine a couple of custom brass eyelets that are slightly larger than the 1/8" keystone ones.
The two preamp cathode ground points are quite tight with 6 leads in each eyelet.
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amplifiednation wrote:Looks great Steve! That is almost identical to my build! What did you put in for NFB? What value for the ceramic cap?
Thanks Taylor. Ceramic cap is 500pf and the NFB resistor is a 3.32k Mepco RN65.
I got my preamp tubes wired in this evening. I would appreciate any feedback on my lead dress.
Please forgive the graininess in the pictures...I was messing around at ISO 6400 on my camera earlier and forgot to bring it back down before shooting these.
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amplifiednation wrote:I hate to be the first one to comment....but that lead dress on the preamp looks perfect. Pics look great too.
How are you implementing the FET
Thanks!
fet will be true bypass on a relay. Only accessible by foot switch. In hindsight, i probably should have added a toggle on the back for the fet relay.
I biased the fet on the bench as per Martins instructions.
Thanks for the feedback guys.
I tried to look at alot of pictures before I started routing the leads.
Hopefully the time and attention to detail pay off at the end.
One minor hiccup on power-up: the shorting jack I used on the main speaker output was not breaking contact with the plug inserted.
I even used the "nicer" mil-spec switchcraft C12AX jacks. Oh well, I tweaked the shorting leg and it seems better. I will probably replace it anyways.
Voltages on the preamp seem a touch low, however I wanted to see what a few other folks thought before I started messing with stuff.
I attached my voltage chart below.
I didn't add it to the chart, but the voltage after the 150k on the fet board is about 17.8V
Pictures to follow in a little bit.
Steve
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Congrats Steve
how does it sound?
Agree with 67plexi on the resistor change
You might also try some other tubes or swap them around.
I have to say my 100 Watt 70's style is just now starting to soften up.
and sound better to me after about 20-30 hrs on it.
You might burn in with some JJ's or Chinese tubes.
Again congrats its a really cool circuit...my favorite at the moment.
So far, it sounds pretty good. I will make the resistor swap tomorrow and report back on voltages.
The clean channel breaks up a little bit using the bridge pickup of my les paul, however I think this will clean up with the voltage increase.
Attached are some pictures. I hope to get some better ones with some natural light. I just have to wait for 2 feet of snow to melt first.
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