I put 25uF at cathode of V1A and....

[pula58]

I am doing some work on my friends Brown Note D'Lite 22/33W. I changed the mids cap in the tone stack from 50nF to 10nF. And, my friend wanting more of a Fender-like bass reponse, I replaced the 5uF V1A cathode bypass cap with a 22uF cap.

The clean sounds are o.k....but..and I don't know if I am imagining this or not, but when I now engage the PAB it sounds muddy. Or at least, more muddy than I remember it being with the 5uF cathode bypass cap.

Anyone want to comment on this?

Thanks!

P.

[alvarezh]

Hi P, from what I have gathered, Mr. Dumble is a very smart guy and an avid experimenter. I am bound to believe he found out very early that high value bypass caps did not work well on his designs, as none of the schematics that I have seen of his "ODS" amps use 25uF values.

I have not experimented on anything higher than 5uF because I did not have the need to. But, if it may be of some help, I will give you a simple solution I have used with some of my (non "D" style) amps:

Install a SPDT switch with two different bypass cap values. The reason I went this route was to better accommodate de differences between HB and SC guitars as opposed to trying to get rid of mud, but it could work for your purpose.

On my "D" amp I am using something similar to alter the value of the mid cap, I parallel a another cap to increase the total capacitance.

Also, you could substitute the switch with a relay that activates together with your OD relay in order to have the proper bypass cap in each mode.

All the best.

[noworrybeefcurry]

Hey there, I totally went for the fendery clean thing and then a dumble drive all in the same amp. It just dosent end up working together...........Ive tried different combinations of 5uf, 10uf, 15uf, and 22uf on the first two gain stages. The biggest issue I ran into was obtaining a big and open clean channel with a clear and defined overdrive. What I found was, the bigger you go with the VIA and VIB bypass caps (anything bigger than 5uf) The more you open up the cleans, but the overdrive gets muddy really fast. Right now I've got a 5uf, and 10uf combination and that seems to be working well.

[Structo]

Put the 10 and 50n mid cap in parallel on a switch.

Put a .68uF on V1a cathode and put a 4.7uF cap on the same switch.

So in one position you have the 10n and .68uf and in the other position you have the 60n and a total of 5.38uF.

Should work well for single coil as well as humbuckers.

[greiswig]

Not sure if there would be a pop or not, but you could have a relay switch in/out a second capacitor(s) on the V1 cathodes, such that you have higher values for clean and lower ones for overdrive. I thought about doing that for mine, but honestly I've got ample bass on the clean channel of my dual-KT-88 build.

[heisthl]

Hey there, I totally went for the fendery clean thing and then a dumble drive all in the same amp. It just dosent end up working together............

Treat V1A plate/cathode values like a Fender but leave V1B like a high plate Dumble except for a smaller output coupling cap. You really can have it all.

[pula58]

Henry,
It seemed like when I changed my buddys D'Lite 5uF V1A cathode bypass cap to 25uF that the PAB became muddy...but I did not have a chance to A/B it. Am I imaginging this, or is it a real effect?

[heisthl]

Henry,
It seemed like when I changed my buddys D'Lite 5uF V1A cathode bypass cap to 25uF that the PAB became muddy...but I did not have a chance to A/B it. Am I imaginging this, or is it a real effect?

You're probably right, I guess I've never tried it with a D style PAB, try the stack lift type PAB.

[noworrybeefcurry]

I changed V1A to a 100k/1.5k combination and left V1B as a 150k/2.2k. The cleans did have a bit more of that fendery spank, but the drive seemed to thin out alot....i didnt care for it to much. Any ideas?

[heisthl]

I changed V1A to a 100k/1.5k combination and left V1B as a 150k/2.2k. The cleans did have a bit more of that fendery spank, but the drive seemed to thin out alot....i didnt care for it to much. Any ideas?

Try manipulating the usual suspects, Cathode bypass caps and coupling caps. Trial and error-ing an assortment of values (within reason) goes a long way to making your ears happy. Also get the V1 plate voltages right (200v +5 or -10) before you do anything.

[bepone]

if you dont use pedals in front of an amp, V1a cathode cap you can put any cap bigger than 5/10 uF without noticeble changes,
but cathode caps in V1b, V2a, V2b, etc like guys allready says, are important..