changes to my 3 channel amp...help

[Bob-I]

After completing the HRM amp in the Peavey chassis I decided to make 2 changes to my 3 channel amp.

1) Change the reverb ckt. The Fender style just doesn't sound right.


The reverb sounds 100% better, but is weak. I used Normsters layout and ckt but it has to be all the way up to be effective. How can I fix this?

2) Change to an HRM

The amp is far fatter and smoother with this ckt. The Hybrid is rough and rude, not in a bad way it's just not the sound I like.

[Normster]

After completing the HRM amp in the Peavey chassis I decided to make 2 changes to my 3 channel amp.

1) Change the reverb ckt. The Fender style just doesn't sound right.


The reverb sounds 100% better, but is weak. I used Normsters layout and ckt but it has to be all the way up to be effective. How can I fix this?

2) Change to an HRM

The amp is far fatter and smoother with this ckt. The Hybrid is rough and rude, not in a bad way it's just not the sound I like.

Gary's reverb circuit is pretty subtle, definately NOT Dick Dale. A few things you can try:
1. Per Gary, throw a small (100pF?) cap across the reverb pot. This will fatten it up a bit at low volume but may be too much as the volume increases.
2. Reduce the size of the reverb return resistor at the PI. It's the 470k. Maybe tack a few different values over the top to see if it works for you.
3. I haven't tried this yet, but Gary's circuit has an 820R cathode on V3a and a 2k2 on V3b. The Reverend Kingsnake has the same circuit but has the cathode values reversed. (It also uses 22uF bypass caps instead of 5uF.) From the reverb return it has a 250kA feeding a 220k to the grid of the next stage. Plenty of reverb on tap! However, the Kingsnake uses a cathode follower tonestack so I'm not sure if that has any effect on the values in the reverb circuit.

[Bob-I]

Thx Norm. I changed the 470k return resistor to a 220k, anything lower added too much NFB to the reverb. I also swapped the 820 cathode resistor wtih a 2k2 but the return resistor had more effect on the reverb intensity.

Like you said, it's not Dick Dale but it's nice.

[keithrick]

I hate to put words in someones mouth especially when I have a cursery understanding of the subject but.... I thought I saw Scottl mention in a previous post that you can adjust the dwell by reducing the 1m resistor to the input grid(V3a). I believe he suggested 470K. Hopefully he will chime in and set the record straight.

I like the circuit,however, it is subtle. What I do is ride the fine line where it starts to bog down the tone and the reverb can get pretty intense. If I crank the pot to 10 it reduces the signal but I do hear Dick Dale trying to get out.

As my friend puts it....How can we release the good

[Bob-I]

I hate to put words in someones mouth especially when I have a cursery understanding of the subject but.... I thought I saw Scottl mention in a previous post that you can adjust the dwell by reducing the 1m resistor to the input grid(V3a). I believe he suggested 470K. Hopefully he will chime in and set the record straight.

I can try that. I spoke with Scott today but we didn't talk about this mod, he suggested using parallel triodes to boost the signal. I'd rather not simply because I can use the extra tube for a Dumbleator (Are these amps ever done?)

I like the circuit,however, it is subtle. What I do is ride the fine line where it starts to bog down the tone and the reverb can get pretty intense. If I crank the pot to 10 it reduces the signal but I do hear Dick Dale trying to get out.

I agree, I like the tone much better than the Fender ckt, I just need a tad more to get the amount of reverb I like in dead rooms.

As my friend puts it....How can we release the good