Home › Forums › Design and Building › 2 Stroke Amplifier Design and Building › But there is no sound, except for a hum …
- This topic has 14 replies, 3 voices, and was last updated December 31, 2011 at 2:08 am by Humle.
December 26, 2011 at 11:10 pm #5179
Then I built my two stroke amp.
But there is no sound, except for a hum …
I have measured the woltag in the amplifier.
And when I measure right down at the 022uf cap (to the left), by the two 100 ohm resistors. The woltag is only around 100v..
Anyone have an idea what the problem might be?December 27, 2011 at 1:54 am #5537
it’s alive!December 27, 2011 at 2:51 am #5538
Probably not the voltages. Check all the grounds for continuity, check for grounds where there should be none. Double check the input jacking wiring, the shield goes to ground (important: one end only), the center lead goes between the tip lug of the input jack and pin 2 of the preamp tube (the 12AX7). Double check all the solder joints , post some photos if possible. Let us know if it resolves the issue. There are other things to check so, do this first and report back. Be sure to use a current limiter so you done create a short and fry anything (like a transformer).December 27, 2011 at 4:44 am #5539
I found the error, had forgotten the cord from v2 pin 6.
Now I just test it with my guitar tomorrow.December 28, 2011 at 12:44 am #5540
Then I tried it with a guitar ..
The sound is extremely muddy and strong distorted …
Does anyone have an idea for how to solve it?
Have made a change. I have not used a reflector tube but 4 diodes instead
To make a rectifier bridge.
I have uploaded some photos in my gallery
photosDecember 28, 2011 at 1:12 am #5541
The SS rectifier looks correct and, if anything, should give you tighter bass and slightly more mids than the tube version. I can’t tell from from the photo, do you have a 4 ohm and 8 ohm jack? Do you have the same tone issue with both jacks? The Two Stoke can be surprisingly loud (for an 8 watt amp), especially with the SS rectifier. Are you using humbuckers? Does the Boost switch change the tone?December 28, 2011 at 1:20 am #5542
Double check the wiring on the socketsDecember 28, 2011 at 2:18 am #5543
Yes it is 4 and 8 ohm jack.
It’s the same with both jacks.
My guitar is a good old Tokai Start.
Expected to get a good Start sound.
I must check the wiring on the sockets again.December 28, 2011 at 2:23 am #5544
One output jack is wired for 4 ohms and 1 output jack is wired for 8 ohms, correct?December 28, 2011 at 2:28 am #5545
Yes that is correct.December 28, 2011 at 2:44 am #5546beelzebumParticipant
It looks like your volume and tone pots might be wired incorrectly. Double check them.December 28, 2011 at 3:44 am #5547
Now I have I checked the wiring to the pots and sockets and everything should be right.
I could not find a 500 ohm resistor so have used a 470 ohm. Did not expect it to have a large impact. Have tried to put a resistor more at 36 ohms so I came up on the 500 ohm. but it did not solve anything.December 29, 2011 at 12:50 am #5548
470R to pin 8 of the power tube is fine. The cap from volume pot to tone pot is 500pf. Hard to tell from the photo but I think Beelzebum might be on to something. Check the shielded lead from the center lug of the volume pot going to pin 7 of V1.December 29, 2011 at 2:01 am #5549
Yes, the cap from the volume pot to tone pot is 500pf.
And yes, the shielded lead from the center lug of the volume pot going to pin 7 of V1.
I’m Afraid I’ll have to find a Tech..December 31, 2011 at 2:08 am #5559
Finally! I found the error, the preamp tube was bad!
so no need of a tech
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