Jeff, one thing, a 1M resistor has appeared across the Drive pot, is this correct? Haven't seen that before, although there is a 1M OD tone pot on the schemo?
Hey Jeff is that correct, the drive pot feeding the power tube grid, NOT from the wiper? I have seen tone controls like that, but is that actually how its done? I dont see that in the HRM. Cheers and thanks for the good work mate!
Hi guys, I am nearing completion on this build and am just wiring in the boards, PT/OT etc.
As you know, I am not that experienced so if anybody can take a quick look at the points mentioned above, I would be grateful as I DO REALLY want to keep the smoke in, folks
If you could look at the PDFs of the layout and schematic and check them, that would be superb!
rogb wrote:...Jeff, one thing, a 1M resistor has appeared across the Drive pot, is this correct? Haven't seen that before, although there is a 1M OD tone pot on the schemo?
Thanks
Rog
Rog,
to my mind that 1M across the Drive pot results in a near linear 200K drive pot.
I have been trying to follow all the updating, but have become confused and lost the plot!
Good luck with firing up, and let us know your voltages, best, tony
Guys, I have not built the amp & have no current plans to do so.
I simply posted the schematic for discussion.
Mat reviewed the schematic with me several times and he indicated that what you're looking at was correct prior to posting it & he also indicated having the pot wired going into the EF86 grid as in schematic. In fact, IIRC, he changed how I had the pot wired to what you're currently looking at.
Perhaps there are now mods, edits or corrections that Mat might be willing to share, but I don't know?
As long as the circuit makes sense as far as signal path and power flow go, and I have checked this to the best of my ability, it will be fired up next week as I am away now till Monday.
Thanks too, Overtone, the 1M on the Drive isn't mission critical so I can see how it goes without it for now, I guess.
azatplayer wrote:Cheers mate. Im working on my layout today, proly start drilling and punching the chassis too. Quite excited actually!
Good stuff!
All my parts have arrived now, just finishing off the cab this weekend.
Any help you could give with pics of your layout would be really great.
Hope to start building on Monday and I am not 100% decided on the layout, being a recently graduated noob
I am going by the AX84 boards but with D style power and pre amp boards, if you see what I mean.
One small change will be a 500K trimmer in place of the mid resistor as I like to tweak my mids, also a parallel 6V6 socket, so I can experiment with differen tubes. Also a bias adjuster as per AX84.
Good luck mate!
How you going Rog? Getting there yet? Interested to see what result uure having
I am back on it buddy, and close to hooking up my boards, but I am having some last minute nerves and REALLY checking everything is OK before hook up the bulb limiter and fire up the 86.
Jeff that's great buddy, thanks, the OD1 and OD2 are now reversed.
I am literally going to wire those in today, so great catch guys!
I made PDFs of the files.
Question, are the OD1 and OD2 still reversed on the schematic?
Also, on the schematic the volume pot is kind of labeled "trimmer" but that wouldn't work. Looking at the photo of Matt's 86 I see a trimmer but there is so much going on in there it's hard to follow seeing that it doesn't follow what it is the layout and schematic which don't seem to show a trimmer unless its the OD tone.
10thTx wrote:Matt's amp does NOT have a volume pot on the chassis. He uses a trimmer pot internally. Hope that answers your question.
With respect, 10thtx
Really? Why? How is it set?
Thanks
Eric
Hi dreric,
All of my D-style builds I seldom use the pre amp volume pot. It always stays at 12:00 or 1:00 o'clock. So I skipped that one from the front panel. On my next build I have been thinking to put the pot under the chassis so I can tweak it if need be.
