Ceriatone ots, hrm.

[Frankie]

please Frankie post enough info...

all the voltages before and after warmup including voltages at tube grids

detailed picts of the chassis

sound samples

I would suggest a coupling capacitor leakage or something similar

thanks
Teo

[67plexi]

Frankie Why the 220uf @350vdc filter capacitors ?
What was wrong with the 100uf@350vdc ? like HAD used ???

[Structo]

At one time I piggy backed two 100uF on the two 100uF filters to see if that tightened up the bottom any.
So 100uF total with the two 200uF in series.
It did help a bit but I reverted back because I didn't like how it felt when the amp was turned up quite a bit.

For the 50 watt version of this amp, 50uF total on the first filter is probably best.

[Frankie]

At one time I piggy backed two 100uF on the two 100uF filters to see if that tightened up the bottom any.
So 100uF total with the two 200uF in series.
It did help a bit but I reverted back because I didn't like how it felt when the amp was turned up quite a bit.

For the 50 watt version of this amp, 50uF total on the first filter is probably best.

I like the sound of the 220 uF best. That´s a matter of taste.
But that ain`t solving my problem. The amp have the same problem regardless of the 100 and 220.
If i hit the strings hard the change will go faster. If I play light it take a little longer before it change, something must be charging out. It`?s almost like a battery that has little power left, but if you wait a while it will up charge some of the power by itself. That`s how I feel the amp is behaving now.

[Structo]

Do you own a cap tester?

I think one of your electrolytic caps is bad and not holding charge.

But what is weird about that is that you have two amps doing the same thing.

[Frankie]

please Frankie post enough info...

all the voltages before and after warmup including voltages at tube grids

detailed picts of the chassis

sound samples

I would suggest a coupling capacitor leakage or something similar

thanks
Teo

Voltages hrm. They are not changing during 1 hour.

V1 p1. 211 v p3. 1,97 v
p6. 218 v p8. 1,85 v

V2 p1. 211 v p3. 2,09 v
p6. 224 v p8. 1,90 v

V3 p1. 323 v p3+8. 59,5 v
p6. 311 v

V4 p3. 478 v p4. 479 v
p6. 480 v

V5 p3. 478 v p4. 479 v
p6 480 v

B1. 481 v
2. 481 v
3. 456 v
4. 353 v
5. 346 v

[Frankie]

Do you own a cap tester?

I think one of your electrolytic caps is bad and not holding charge.

But what is weird about that is that you have two amps doing the same thing.

Can it be one of the bypass caps on the board then. Those 5 mdf 63 volt?
Can they cause the tone to be thinner, and then charge again to make it full range again?

They are the same brand, from ceriatone. I haven`t swapped those yet.
Maybe I must buy some other brands of them and see if that helps.

I don`t have a cap tester. only a multimeter .

[Frankie]

Frankie Why the 220uf @350vdc filter capacitors ?
What was wrong with the 100uf@350vdc ? like HAD used ???

I use them cause they take away some of the mid.
Maybe if the amp was tuned by HAD it would be better with 100uf, but it seems like the preamp in these ceriatone kits are to narrow, and have a kind of blanked over the amp. It opened up the sound with them. Only that`s why I used them. Nothing wrong with 100uf. Wish I could use the original spec in theese amps, and have it to sound the way a dumble should.
But that`s why we have this forum. Glad we do.

[Structo]

Here's something you could try.

Take a 50uF E cap and clip on some insulated test leads to it.

Then play through your amp until you get the symptoms.
Then clip that cap to an existing cap on the filter board one at a time in parallel to the existing caps.
You may be safer to switch it into standby when doing this.
Process of elimination, if one of those caps is bad, then this should find it.

Also do the same thing for the bypass caps, use a 5uF cap and clip it one at a time to the existing caps to see if one of those is bad.

It still doesn't explain why two amps are exhibiting the same symptoms though.

More B 1 + filtering usually will tighten up the bass a bit but too much can cause the amp to sound and feel sterile with not much sustain.

[Frankie]

Here's something you could try.

Take a 50uF E cap and clip on some insulated test leads to it.

Then play through your amp until you get the symptoms.
Then clip that cap to an existing cap on the filter board one at a time in parallel to the existing caps.
You may be safer to switch it into standby when doing this.
Process of elimination, if one of those caps is bad, then this should find it.

Also do the same thing for the bypass caps, use a 5uF cap and clip it one at a time to the existing caps to see if one of those is bad.

It still doesn't explain why two amps are exhibiting the same symptoms though.

More B 1 + filtering usually will tighten up the bass a bit but too much can cause the amp to sound and feel sterile with not much sustain.

Very good!!


Thank you man.
I will try this. Just have to buy some more caps to test with.
I will let you know if this solves the problem. :)

[bluesy]

.....swapping the speaker cabinet at the time the amp looses its "juice"? Maybe squirrely voice coils?
________
BMW X6 M HISTORY

[Frankie]

.....swapping the speaker cabinet at the time the amp looses its "juice"? Maybe squirrely voice coils?

I will do that, when I got another cab. Waiting for an old evm 12l, coming by mail next week.

[llemtt]

Good pics Frankie, I'll check them to see if I can spot something

can you also measure (before/after) voltages on:

tubes grids

filaments pins

?

as already suggested there must be some unusual voltage building up/down somewhere when you put some signal through the amp while it slowly recovers at idle

faulty caps behavior isn't usually related to the ac signal through them

anyway I also experienced something similar and it ended up to be a bad solder on filaments wiring that was causing a lower filaments temperature

so I can also suggest that something similar can happen if your PT collapse the voltage on the filaments tap as it increases its temp while you play

Teo

[BobW]

Determine if the issue is in the pre or power section by connecting the preamp to another amp via the loop.

Also if you are having the same issue with 2 amps, then try a different cab and speaker cable first.

[Frankie]

Determine if the issue is in the pre or power section by connecting the preamp to another amp via the loop.

Also if you are having the same issue with 2 amps, then try a different cab and speaker cable first.

I connected the preamp from the hrm to my bruno cowtipper power section, and the same problem is still there!
SO it must be in the preamp section. One step closer I hope!