This is a riot! Thanks for posting.
Type: Posts; User: g1; Keyword(s):
This is a riot! Thanks for posting.
Great. You can directly ground the tube side of the ferrite bead. Does the problem remain or disappear?
Something about that drawing format just won't click with my brain, so my OCD forces me to do this. :)
Yes, you will get coldest (full negative voltage) bias if the wiper goes open.
Looking forward to hearing how it works for you. I was concerned about neck dive but watching the video it doesn't look like a problem.
Maybe more money than a regular strap but the price doesn't...
So beyond 1 on the volume pot all sounds the same, or the volume still changes as you turn it up?
If it all sounds the same volume above 1, the pot or it's connections could be bad, or the pot might...
Can you post the schematic? You said the noise goes up and down with volume? Does that mean you can make it go away by turning down the volume control?
Ideally you would test the jack & bead by...
Since he wants to use this amp as a preamp, how about driving the tank with the power amp?
Well, don't forget what shamwow Vince said about Germans, 'they make good stuff'. ;)
Is this the schematic you are using?
Does the clean volume otherwise act properly and vary the volume, right down to zero? Is 2 louder than 1?
A fault like that would not turn up on a tester, and is not unheard of for new tubes. Was the problem already there before you put the new tubes in?
Oh yeah, 'turn it up'!
Really enjoyed 'The Radio'. :)
Can you also measure DC voltage at pins 4 and 5 of power tubes and post them.
The DC filter removes any DC from your audio cable.
As I think there may have been a couple different issues, I'd appreciate if people would listen to the sound files and comment on those issues.
My comment was with regard to the first file in post...
Here's a direct copy:
If you need 9mm instead of 6mm width, then LR50/6 is a good number. I only mentioned the 626 because that is what they are using in the roller you are waiting for from China.
You have the plastic knob on or off the control shaft? Not sure how it could make noise if it is on as it is plastic. Is the nut that secures the pot to the chassis tight?
I think they used to secure those joints with something harder, like epoxy or nail polish. Same as at the ends where the springs hook into the transducer cores.
Those are expensive. If you look closely at the picture you posted of the polyurethane roller, you can see the number 626RS. They just put a polyurethane tire around it.
Here is a plain 626RS...
To me, there also sounded like some power tube rattling in there.
If the problem comes back, change both the EL84 tubes, not just one at a time.
626RS is a standard type sealed deep groove ball-bearing.
The earlier Unicord schematic does show the 6550's have 47K grid leaks for the 6550's. The JCM800's used 150K's.
Now that you are back to 'usual' location, go down to the bottom left of this page and where it says 'vB4 default style' try the other 'mobile' setting and see if that was what you had at the other...
I thought it improbable too, especially with the spring type retainers. BUT it is the only thing I can think of that explains the B+ dropping so much with the 6550's compared to the EL34's, even...
Yes. Leave pins 8 connected and disconnect the pin 1's. Retry your measurements. It's possible the 6550's they were using originally did not have the shell connection. Do the springs or their...
Here's a wild guess. The 6550's are conducting hard. This is shown by the low plate voltage compared to the EL34's.
Something is messing up the measurement at the cathode. Measuring by the OT...
Something is very strange about those 6550's.
They were measuring less current than the EL34's, yet they were pulling down the B+ greatly.
If they were really conducting less, the plate voltage...
Apparently Form D is 'make before break' aka 'continuity transfer'. Form C is 'break before make', Form D is the same assignment as Form C but is 'make before break'.
So during the switchover,...