Frequency doubling

[35L6]

OK , got them both up . Better than I did yesterday . So , its 100 mA into the HI input , 1V/ division with 10 to 1 probe so 10V / division . Gain at max . Taken at treble pot . The double image is a time base error . 640 Hz . Obviously quite distorted . I haven't built the audio probe yet because I unsure about grounding . I would be connecting the ground of one amp to the ground of the other . Not sure if that is a good idea but if the hum wasn't too bad and nothing blew up I could listen to each stage . I had already removed the 470p following the cold clipper and last night I put it back and removed the 470p before the gain control . That seemed to help some , clipping then boost instead of boost then clipping . I had tried different guitars and different cabs to be sure it was the amp . This may also be like hum and has multiple sources . I have scoped guitar signal and its interesting but all over the place and I don't know I could tell anything from it . I'm using a homemade guitar with strat pickups and have had that ghost note thing and it does sound similar .

[g1]

post #13 does not show anything for me, just a blank post.

[35L6]

I see a picture on 13 but I just lost the one I was writing . I'm going to try to post a gut shot . Let me know if you can see 13 .

[35L6]

I'm posting this gut shot so the rest of you won't be ashamed to post yours . Not happy with the layout but I had to build it to learn how . When I get circuit worked out I'll build another with better layout . My goal with this one was to make all the mistakes so the next one would be better . So far thats been working out .

[35L6]

With this layout the terminal strips are too far apart and there are too many flying leads . On the next one I'll use three terminal strips and move the power supply stuff to the outer one so I can secure both ends of the filter caps . Also I use an IEC inlet with fuse holder and move the rectifier to the other side of the PT where the fuse is now .

[The Dude]

Please don't take offense to this. It's meant to be a tip more than me being a critical a-hole. When you are making joints like the example below from your picture (and I see lots of them), it's better to loop both leads, crimp together, then solder, so that the joint isn't completely depending on solder for stability and reliability. For clarity: take your two forefingers, bend them and hook them together, then squeeze. Hopefully that explains what I'm talking about.

[35L6]

Point well taken . I did a couple where I made a loop around the tip of my hemostats and slid the other wire through . You can adjust the length that way . When I'm prototyping I like to be able to take them apart easy . When I stop making changes I going to build another and secure both end to terminals .

[g1]

Still can't see post #13 image. Can anybody else see it?

[The Dude]

Nope

[Greg_L]

Man I sincerely mean no offense but that thing is a mess. You really shouldn't just haphazardly stick these things together and expect them to work flawlessly. I understand your "proof of concept" idea, but you're not doing yourself any favors by building like this. Just by the looks of it there's an infinite number of possibilities for noise and interference and crosstalk and oscillation and bad connections.

[35L6]

Do you see it now ?

[g1]

Yes, post #26 image is visible.

[35L6]

Today I added a grid stopper to V2a . I think it's a little better . A sudden dramatic change would have been more satisfying . Makes me think of posts where someone says " my 5150 squeals when I crank it with the treble full up " and the reply is usually something like " I'm not surprised ! " Maybe this is just the nature of the design . It sounds better than it looks . I think I'll play it for a while and see if I get inspired . More grid stops and better layout may improve it but it's playable as it is .

[loudthud]

The layout isn't that terrible, but no points for neatness. It looks like you just wired it up on the fly with no up front drawing. You might benefit from grounding pin 3 of the preamp tubes.

Does your scope have a control called Holdoff ? You'll find it on the more expensive Tektronix scopes. It ads a variable delay after the end of the horizontal sweep before triggering is enabled. Otherwise, try to use the external trigger to another output from your generator.

How much power does this thing make ? Should be able to get 10W or so with the right OT.

[Helmholtz]

Otherwise, try to use the external trigger to another output from your generator.

Or maybe just select the used channel as trigger source?

It's a simple audio signal. Shouldn't be hard to trigger.