Finished up a D Lite last week using most of the "suggested" changes. Sounded terrible at first. Kind of "flat" on the clean and the OD was VERY harsh. Today I turned down the OD trimmer (~25k to ground), removed the FX loop (just to make sure), changed to un-shielded wire to the MV, biased slightly colder (~35mA) and played with the lead dress on V1 and V2. The biggest change came from the lead dress on V2 - moving wires 1/16" made a very noticeable difference in the "smoothness" of the OD.
Sounds MUCH better now but I think I found a couple of issues and have a couple of questions.
I used 50w Bassman OT with 4K primary and 2,4 and 8 secondaries. I have the presence circuit connected to the 4ohm tap. Is this correct?
I also found that I only have 415vdc on the plates of V4 and V5. I'm using a 320-0-320 PT. I'm getting 320 at the rectifier board and 420 after the diodes. Is the PT voltage jsut too low ar should I look for an issue elswhere? Dropping string is currently 1k - 18k - 2k2. I plan on changing the 1k to a 3k3 as this seems a little more "common". Would that help?
Any suggestions, comments are appreciated.
You do not have the required permissions to view the files attached to this post.
Your plate voltage seems low. I think it should be around 450 VDC for a 320-0-320 PT. But before you start tearing things apart, check your wall voltage. If you're seeing about 109-110 VAC, then your power supply is doing it's job.
"Let's face it, the non HRMs are easier to play, there, I've said it." - Gil Ayan... AND HE"S IN GOOD COMPANY!
Your plate voltage seems low. I think it should be around 450 VDC for a 320-0-320 PT. But before you start tearing things apart, check your wall voltage. If you're seeing about 109-110 VAC, then your power supply is doing it's job.
My wall voltage is 117vac. I'm getting 320vac out of the PT but only about 419vdc after the diodes.
Tom,
The resistor from the bass pot is tied to the first lug of the mid pot. From there, they are both tied to ground through the PAB relay. The PAB relay breaks that ground connection and inserts a resistor.
I have 2 different bright caps and a 3 way switch (off, 120pf and 270pf).
I don't have another pair of 6L6's handy but I did swap in a set of 6V6's and got ~434vdc. Not sure if that is normal. I'll try to dig up another set of 6L6's to try tomorrow.
Sound improved slightly (it's late and the kids are in bed so it's hard to know for sure). I also cut the jumper on the bass pot from lug 2 to 3. Another change for the good.
I'll probably pull the rectifier/bias board tomorrow and double check that too.
Transformers can vary in spite of their ratings. What is the voltage on B+1 with no tubes? Theoretical high is just under 460 volts. If it's under 445 without tubes I'd go hunting, else all is probably well.
sounds like an output tube drawing too much current... if the 6V6's were in the 434 range and you're getting 449vDC with the output tubes pulled, I'd get my hands on another pair of 6L6's and try them... also, what bias setting are on those 6L6's? Whats the reading at the test jacks?
They were biased at 35mA. The only others I currently have are another pair from the same "quad" and I just found an old set of Sovteks - I'll try both out tonight.
Tried a pair of Winged C's today and got 429 on the plates. Still not what I was hoping for but better. Should get a chance to play it more at volume tonight.
