Menu

Show posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Show posts Menu

Messages - g1

#31
I think if you tweak it to get symmetrical you will still overdrive the stage anyway.  And it won't sound any better if it's clipping evenly on both sides rather than just one.  It's not really meant for that kind of guitar signal.
Some tubes amp do that as well, the gain stage before the volume control clips unless you turn down the guitar volume.  Just that with tubes no one really minds as much because the clipping is softer.

You can tweak the gain of the stage to deal with it, but you might just find the next stage or somewhere down the line clips the same way.

That's why I suggested getting full unclipped output and seeing what kind of input signal level that requires.
#32
Have you verified that the input stage is the first thing that clips before the amp gets to full power?  Seems odd that they would have such little headroom at that stage.
At full power (just before clipping) into a load, what is the peak to peak voltage coming out of the first IC ?
#33
Where did that example come from?  Why did they say the biasing resistors should equal R1?
The ratios are about RF and Rin and set the gain of the non-inverting op amp.  Your circuit and the example circuits have different gain so the "=1/2 R1" does not apply.
#35
When you are getting the 1V from E-C, short the base to the emitter and see if the reading goes to open circuit.  If so, it should be ok.
#36
Amplifier Discussion / Re: Tech 21 Trademark 60 Noise
January 30, 2024, 03:13:56 PM
Yes, it is possible for electrolytics to self-heal.  Whether it is temporary or permanent is another question.   :)
#37
Agree with Phatt, tank should be ok.  Fix the reverb first, then change tanks if you still want to.
Sometimes there is signal but not enough.  The tank takes quite a bi to drive it.  You said you thought it was appropriate but what is the level you are getting in to it?
Also you should be able to get very loud crashing from shaking the tank if reverb and volume are both turned up.
#38
If it is running the chips with single supply, it will have blocking caps at input and output of IC.  Check that they are not leaky.
Also check for protection diodes at IC input.
#39
Normally I would say yes, it is in the power amp section.  But you also said the tone controls affected the sound of the ticking.  If the tick was just in the power amp the tone controls should not affect it.

The item that is common to both the preamp and power amp is the power supply.  But it would still be good to run the preamp out (FX send) to a different amplifier and verify if the tick is there or not.
#40
Your math is off by some factor of 10 I would think.
He has 6.3V and a 47K resistor, you have roughly 3 times the voltage, maybe should have 120K instead of 1.2M ?
Re-check your calculations.
#41
Excellent.  Have never seen one with a stand like that, usually they clamp on to desk.
I like this so much more.  I think I'll try to cobble something together with my desk mount lamp and a broken mic stand.  :)
#42
Quote from: mccutter on January 13, 2024, 09:11:44 AMIt's called CR13 (one of these in the heat sink)
Seems to be good but the vf value is different from the others (616mv vs 840mv)


CR10 to 13 are critical to the bias circuit as they compensate for the heatsink temperature.  The Fender part # for them comes up as BYV26E.  You should replace all 4 just to be safe.

Also, what I said earlier about checking for DC with no load won't work on this amp, because of the IC driver.  You will need some resistor on the output instead of the speaker, 1K should be safe for testing.
#43
Do you have any electronics on your person?  I don't know many people who do not.  Turn them off and see if it has affected anything related to the fault(s).  It may seem like a long shot but it's something that must be eliminated as a possible cause.
#44
What is that BYV26D diode called in the circuit?  CR18 or 19?
Disconnect one end of it and recheck.
#45
Once you learn all those equations backwards and forward, you will have a much easier time with practical applications like multiple speaker cabs with speakers of various impedances.  Then you can throw power handling into the mix and find the weakest link.   :)