Class 5 bass mod - tighter lows advice

[shaun]

Reading on the My Les Paul forum about the Class 5 mods (Lyle Caldwell), would adding a 1M resistor across the current R18 resistor (1.8K value i think it is going by schematic) give the tighter lows.?

Is is a very long thread over there, and i have done the bright switch already - which works great at low volumes.

Thanks.

Edit - the mod schematic is in the 'schematic' section in this forum.

[shaun]

Well i tried out the bass mod anyway, as described by Lyle Caldwell, and i either did something wrong, or the results were nothing. I did not notice any difference at all, even with the selectable switch. I attached the switch to R18 via alligator clips to try it out first, and then disconnected it.

My conclusion is that the speakers, and guitar pickups make the overall biggest difference with this amp.

[jeffsmusic4919]

Hey Shaun, sorry about your troubles. If you wired it like the attachment it should be correct. This is switchable parallel wiring.

Have you tried using unorthodox EQ settings? Such as bass on zero, add volume then adjust the highs and mids from there. The speaker should move different, with pure Marshall power. With the power dimed or close it will be a bit of a balancing act though. Some tubes break up different than others and high power can turn tubes into mush in the bottom end.

As for pickups, a Duncan Distortion is as about a tight as a pickup as I have ever used. Pair that with a Marshall Shredmaster pedal. That equals some really tight bass. If you can't get tight with that, time for a different speaker. I use a Shredmaster and a Vibrolux (non-master amp) with alnico speakers which aren't very tight 10" speakers if I remember right from reviews. I am pretty satisfied with the tightness of the amp. And I am pretty obsessive about tight bass.

Hope this helps some.

[shaun]

jeff, i have a JJ EL844 poweramp valve in the C5, which gives more compressed gain. I did not think about this at the time, so whether the different valve makes the mod less prominant, i don't know. I much prefer the EL844 to the EL84, and i still have the switch resistor/cap assembly so it can be put back in easily enough. I triple checked the assembly and everything appears ok.

When trying the amp with the mod removed, it still sounded pretty good when cranked, so i don't think i will worry about it at the moment. Comes down to correct speaker/cab choice more so i think, to get rid of the loose low end.

I have a B cab with greenbacks/blackbacks, and a 2 12 cab with a greenback and Celestion T652 (the 2 12 can be used as each speaker seperately or combined)

[jeffsmusic4919]

Well, I am sure you will get what you want from the amp in time.

I read about five pages of the forum post that you read. Boy, I am so glad Surf got this forum together. If their were some of this here........ My thoughts were, "who pissed in this guys coffee". I appreciate the skill it takes to know schematics so well. But the tone in which it was done was kinda mean spirited and tasteless. In my opinion anyway. Making posts like that can make people like you who bought those amps with hard earned money feel like they made a bad choice. Even if you and others are satisfied with their purchase.

In the matters of amp design, there are factors in the decisions that are made behind the scenes that are unknown. Like, a good amp engineer has good ideas but their boss says, "no". Or the circuit design is to similar to a competitor and is nixed because of company pride or fear of being sued. The list goes on and on with perceived reliability, parts availability and materials cost. I really don't want to get into a long rant so , I will stop now. No need to blow a fuse.

To be fair to him though, his mods did seem to make sense with his given reasoning. I just wish he had done it with more tact. Thanks again Surf for a great forum.