Dumble ODS Clean Channel question (too clean?)

[67plexi]

I just tried the JJ/6V6-S not impressed harsh and brittle.
This may help.


Steve.

[Charlie Wilson]

Yeah, I think the only good reason to use the JJs is were voltage may be an issue. They sound more like mini 6l6s to me. The other thing is that amps that run the plates over 400v with 6v6s always sound I bit harsh and break up a little hard, to my ears. I always like a Tweed Deluxe with plates between 350-380v. Not as loud but nicer sounding. The best new production I have heard is the Tung Sol reissue 6V6 but you have to watch the voltages.
CW

[ToneMerc]

I've built 4 quad 6V6 ODS style amps, both classic and skyliner tonestacks, both high and low plate versions. I purposely setup the power transformers with lower voltages at around 385-405V because I dont like the JJ6V6 at 450V for same reason as Steve. I prefer the TS reissue even at the lower plate voltages.

My quad 6V6 5F8A Twin with 370V on the plates has TS reissues in it.

TM

[talbany]

This is true!!..JJ's @450 can have a kind of harshness to them that seems to ride on top of the note..When really pushed can get a bit fuzzy..At that voltage they are fast hard and real strident and sound louder due to the midrange push and will slice through the mix!!...The harshness seems to go away (or help) when you run them under 400V (350 about perfect)..The good thing about them is they do have more headroom and a bit more stout than most 6V and can sound a bit bigger,which is probably why Dumble used them in his Tweed conversion Charlie posted..The right tube if your chasing mo headroom but a far cry from the sweeter softer 6v's of old!!

Tony

[ericlc]

Sure, I agree.
JJ's 6V6s are more little 6L6s that old school 6V6's.
And I chose them exactly for that reason, little 6L6's.
Building a Fender Deluxe clone is on the list.

But that was not the reason for starting the thread;-)

My amp was just very clean, too clean for my taste.
After measuring the voltages today I found that the pin 3/8 voltages at the PI were a bit high. So, I replaced the tail resistor (from over 25K to 22K) to bring it down from 63V to 55V. I also increased the GNFB resistor to 5K6.

I am now happy with the amp, at least for now:mrgreen:

Thanks to all of you for your suggestions, opinions and advice

Best,
Eric

[splgeo]

Can you post clips if the amp? Id like to hear it and try the pot for the gnfb resister

[ericlc]

I'll try to do that later this week.
It's quite busy at work this week.

My observation is that you get a little bit more gain but also a bit more treble and noise. I started out with a 6K8 resistor and settled for a 5K6.

I might even go back to 4K7 (or use the 8 Ohm speaker tab )now I have fixed the PI.

I'll see if I can create 5K6 and 4K7 samples.

/Eric