PMD Tone w Jalen FW Pickup

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Re: PMD Tone w Jalen FW Pickup

Post by PLX »

harddriver wrote: Mon Sep 19, 2022 3:24 am I thought you went with just the .68uf cap on V2A. Did you go back to the 330uf or 25uf fat cap as well?
I went to look for photos because now I can't remember what the hell I did in there.

:?
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Re: PMD Tone w Jalen FW Pickup

Post by harddriver »

Those are the old pics before you rebuilt it. Last pic I seen after the rebuild you had a .68uf Royal Mustard on V2A.

The 330uf fat cap makes any amp sound bloated IMHO. I just went back and looked at you REEEEEEEEEbuild pics and you installed the .68 uf there. I just didn't know if you changed it from the 68uf to the 330uf cap again since the intial rebuild pics. If you are going to keep the 330uf cap I would find a way to put it on switch if you like it for ED stuff but I wouldn't go any higher than a 25uf there. If you like your crunchy mids then a .68uf is all that is needed IMHO. Even an unbypassed 820 at V2A sounds pretty darn good, but the .68uf makes things tighter and more focused in the mids.

So if you're amp is a standard JCM800 layout to a tee crank that preamp gain to 7-8 and turn the presence to 6-7 and treble to 6-7 and see what you get as lll also suggested. Remember Nuno's tone is bright as shit............... ;)

100K NFB would definiely be more NUNO versus the 47K... but I have a solution for you Read on.

Also the 47K plexi NFB you chose makes the attack a little softer spongier. The 100K make things more ratty the 47K is more plexi polite like. My best of all worlds solution since you have open pot hole on your chassis is remove the 47K resistor from your circuit board and install a 100K Linear pot(variable resistor) so fully cranked would be JCM800 Marshall NFB of 100K and turned half way up is 50K(47K) plexi.... walla you have the best of both worlds easy peasy.......... 8-) ;)

What Impedance tap is your NFB connected to 8 ohm or 4 ohm?
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Re: PMD Tone w Jalen FW Pickup

Post by PLX »

harddriver wrote: Mon Sep 19, 2022 3:43 am Those are the old pics before you rebuilt it. Last pic I seen after the rebuild you had a .68uf Royal Mustard on V2A.

The 330uf fat cap makes any amp sound bloated IMHO. I just went back and looked at you REEEEEEEEEbuild pics and you installed the .68 uf there. I just didn't know if you changed it from the 68uf to the 330uf cap again since the intial rebuild pics. If you are going to keep the 330uf cap I would find a way to put it on switch if you like it for ED stuff but I wouldn't go any higher than a 25uf there. If you like your crunchy mids then a .68uf is all that is needed IMHO. Even an unbypassed 820 at V2A sounds pretty darn good, but the .68uf makes things tighter and more focused in the mids.

So if you're amp is a standard JCM800 layout to a tee crank that preamp gain to 7-8 and turn the presence to 6-7 and treble to 6-7 and see what you get as lll also suggested. Remember Nuno's tone is bright as shit............... ;)

100K NFB would definiely be more NUNO versus the 47K... but I have a solution for you Read on.

Also the 47K plexi NFB you chose makes the attack a little softer spongier. The 100K make things more ratty the 47K is more plexi polite like. My best of all worlds solution since you have open pot hole on your chassis is remove the 47K resistor from your circuit board and install a 100K Linear pot(variable resistor) so fully cranked would be JCM800 Marshall NFB of 100K and turned half way up is 50K(47K) plexi.... walla you have the best of both worlds easy peasy.......... 8-) ;)

What Impedance tap is your NFB connected to 8 ohm or 4 ohm?
It's connected to the 4Ω tap.

I finally found the photo.. I put the Royal Synergy 68 as the fat cap (like you had recommended a while back).
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Re: PMD Tone w Jalen FW Pickup

Post by harddriver »

I also forgot to ask if you are variacing the amp down on the Nuno clips? I would not variac the amp down below 100-110 VAC for the NUNO stuff.

This will raise the plate voltage on all the tubes and make the amp tighter brighter and more hard edge distortion versus the brown kind of saggy
EVH distortion.

You probably have a 100K linear pot laying around to install. Install it in next your presence pot in the next open chassis hole and wire the input NFB wire from the circuit board that normally feeds your presence(shielded cable if you have it) add another wire to the lug and it will also connect to the wiper(center lug) of the 100K pot then the output lug connect to the 4ohm impedance lug with purple wire. You now have a variable NFB 0-100K NFB. 8-) It's been awhile since I did this but I think what I laid out is correct. I'll try to post that pic I found.

I am fairly sure I made a thread about it on Metro while I was doing it. I think I used a 250K linear pot. I found a pic of my 4 stage amp of how I did it in that amp. In that amp I left a 27K NFB resistor on the board so the amp always saw 27K then I added the pot in series with that but you have to pre-mark the detent resistance positions of the pot before connecting it for desired NFB setting. 27K + 20K(NFB pot)= 47K(Plexi) : 27K+29KNFB pot)=56K Mesa Boogie/Cameron NFB : 27K + 41K(NFB pot) = 68K Cameron : 27K + 73K(NFB pot)=100K Marshall JCM800 : 27K + 147K(NFB)= 220K Splawn

If you only want 0-100K then the 100K linear pot would be the way to go that way half up is 50K and cranked is 100K. It's a great addition to any amp were you want to be able to go between Plexi saggy and JCM800 tightness. Then just remove the 47K that you have on the board altogether then and put the 100K pot in place of the resistor as I described.
Last edited by harddriver on Mon Sep 19, 2022 4:05 pm, edited 4 times in total.
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Re: PMD Tone w Jalen FW Pickup

Post by harddriver »

PLX wrote: Mon Sep 19, 2022 12:25 pm
It's connected to the 4Ω tap.

I finally found the photo.. I put the Royal Synergy 68 as the fat cap (like you had recommended a while back).
That's good it will keep things nice and tight for your NUNO stuff and it works for ED stuff so you're covered there.
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Re: PMD Tone w Jalen FW Pickup

Post by harddriver »

You'll see i moved the presence pot to the back of the chassis due to lack of holes on the front but you don't have that problem. 8-)

Image
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Re: PMD Tone w Jalen FW Pickup

Post by harddriver »

With all that other stuff being said...I think you are neutering your amp tone running the preamp gain a 5 for NUNO tone. As previously suggested try runnning the preamp gain get to 7-8-9 then use the RAT at Nuno settings. Maybe back off the RAT volume level a smidge if you really need to but I don't think you will need to cause ya gotta hit that front end hard for that percussiveness and kerrang of NUNO. ;)

I made my case for NFB so that will be up to you if you want to do that, if you want a true JMC800 tone then you should do it as it will give you the best of both NFB values at the turn of a knob. 8-)
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Re: PMD Tone w Jalen FW Pickup

Post by harddriver »

I would do the pot... but I have another alternative for you as well.

You could change out the 47K NFB resistor for a 100K then you could another 100K on a toggle switch to piggyback another 100K resistor to shunt it down to a 50K value. So that would be two hardwired NFB values if that is quicker easier mod for you to try. Flip the switch to bring in the other 100K in parallel with the 100K on the circuit board giving you 50K NFB. ;)
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Re: PMD Tone w Jalen FW Pickup

Post by harddriver »

Here you go PLX.......my old 2010 Metro thread walks you right through the installation easy peasy......... ;)

http://forum.metropoulos.net/viewtopic.php?t=29899
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Re: PMD Tone w Jalen FW Pickup

Post by harddriver »

I just had another idea PLX. You probably have an extra 50K linear mid pot laying around as well. Leave the 47K NFB resistor on your circuit board then run a shielded wire like I did in my pic to you 50K linear pot. '

With the pot turned all the way down you will have 47K and when turned all the way up you will have 97-100K NFB. So now you have three ways to do this.................. :D ;)
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