Amp Sounds Better on 4-Ohm Tap

The New Steve H · Post by **The New Steve H** » Fri Dec 27, 2013 9:25 pm

It's up and running with the pot taken out. I am still not happy with the distortion. It seems like the problem may be coming from the preamp.

The New Steve H · Post by **The New Steve H** » Sat Dec 28, 2013 12:10 am

Well, it turns out it makes a big difference if you wire the inputs CORRECTLY.

I think I've weeded out all the major errors. The amp is louder now. Still sounds best with the volume below 7, however. Makes me wonder if that PT is going to have to be changed.

Reeltarded · Post by **Reeltarded** » Sat Dec 28, 2013 2:04 am

Well, if it can't take the current draw but it's RIGHT on the line the PT will get "pretty effing hot" and this is a relative statement considering lots of things.

If it requires 20-30% more current cap you will know pretty soon, that condition is supposed to smoke.

matt h · Post by **matt h** » Sat Dec 28, 2013 4:03 am

(deleted)

The New Steve H · Post by **The New Steve H** » Sat Dec 28, 2013 3:30 pm

The schematic I started with had 6BM8s on it. That pretty much sums up my reasoning.

matt h · Post by **matt h** » Sat Dec 28, 2013 3:58 pm

(deleted)

The New Steve H · Post by **The New Steve H** » Sat Dec 28, 2013 4:21 pm

Something to think about.

rp · Post by rp » Sun Dec 29, 2013 1:44 pm

The New Steve H wrote:It sounds great at lower volume.

All life should be so easy. Test is to get it to work and sound good flat out.

The New Steve H · Post by **The New Steve H** » Sun Dec 29, 2013 10:37 pm

I just built an amp with 4 EL84s. It's fantastic. I did want a 6BM8 amp, though.

Today I found a loose diode on the base of the rectifier tube, and I also realized I had 20 uF of capacitance going to the OTs instead of 32, so I added another cap. The amp sounds a lot better now.

One thing I am not clear on: what is the purpose of having a resistor PARALLEL to the capacitors going to the OT? I comprehend resistors going between nodes, but this is different. If it's an RC filter, the figure I get for the cutoff frequency is around .02Hz, which does not seem all that meaningful to guitar music.

The New Steve H · Post by **The New Steve H** » Sun Dec 29, 2013 10:42 pm

And the resistor is pointed the wrong way for an RC filter, so I guess that was not relevant. I am now reading up on parallel RC filters.

Structo · Post by **Structo** » Mon Dec 30, 2013 5:01 pm

Not sure what you mean by the resistor is pointed the wrong way since resistors are not polarized.

Do you mean the cap is pointed the wrong way?

Reeltarded · Post by **Reeltarded** » Mon Dec 30, 2013 5:04 pm

i think he means gnd vs signal. high pass other way is a low pass, fer instance..

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Amp Sounds Better on 4-Ohm Tap

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