Germino Headroom 100 bright cap

DragonCrestPC

Well-known member
I just acquired a Germino headroom 100 and love the amp but i feel it's missing some of the marshall brightness. I emailed Germino and they stated the amp has no bright cap at all. I'm looking to put a original value cap across the volume 1 potentiometer but don't know the original 68 SLP value ( internet forums are all over the place ) Anyone know the original value that would have shipped from marshall back in 68? Also what would be the best material? ( ceramic, silver mica etc etc ). Posting pic below, thanks.
 

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I don't think that there was one value used exclusively as the bright cap value. Marshalls from this era were a little erratic as far as component values go.

This is a good resource: http://www.marstran.com/Historic%20Data%20Base.htm

470pf is a pretty common value for these circuits. It's the value Suhr used in their SL68 ( which is supposed to be a '68 spec plexi clone ala Eddie's amp )

If you want the volume knob to have that on / off effect and the "blizzard of nails" tone until the volume gets up around 7 or 8, then go with 4700pf. Turns the vol knob into a bit of a tone control and produces a killer gain tone. Might not work so good with pedals.

I personally think ceramic caps sound best in these amps. Gives the amp a real "bite". I see that your amp is using silver mica for the mixer bright cap and the treble cap in the tone stack. You could also consider swapping these to ceramic to get a little more of a raw, aggressive sound.
The SL68 uses silver mica for the 3 pf value caps, and that amp sounds way to smooth to me, but what the hell do I know......
Lots of variations possible, and it all comes down to personal taste really.
 
DragonCrestPC":246ehr7e said:
Thanks for the help guys, i remember getting a pack of capacitors awhile back, will these work? https://www.mojotone.com/amp-parts/Cera ... 500pF-500V , cant find any 2000pf or 4700pf anywhere and is there a recommended voltage? Thanks again.
Yeah, sure. Those are fine.
Not the highest quality caps, but it will give you an idea of what 500pf sounds like as a bright cap.
See if it adds enough "zing" to the tone to get you where you want to go.
If it's not quite there, it's easy enough to swap in higher values like 2200pf or 4700pf.
1000pf is the JCM800 value, so you could try that too. Ceramic caps are cheap.

Ceramic caps in these values should be easy to find. See if you have an electronics surplus store nearby. Those little surplus stores are goldmines for cool old caps and resistors.
500V is fine, but a lot of guys ( including me ) think the higher voltage ones rated for 2kv or 3kv sound better.

When you're rummaging through the bins at the surplus, don't forget the value codes:
471 = 470pf
102 = 1000pf = 1nf = .001uf
222 = 2200pf = 2n2 ( 2.2nf ) = .0022uf
472 = 4700pf = 4n7 ( 4.7nf ) = .0047uf
 
fusedbrain":1c9k0v64 said:
DragonCrestPC":1c9k0v64 said:
Thanks for the help guys, i remember getting a pack of capacitors awhile back, will these work? https://www.mojotone.com/amp-parts/Cera ... 500pF-500V , cant find any 2000pf or 4700pf anywhere and is there a recommended voltage? Thanks again.
Yeah, sure. Those are fine.
Not the highest quality caps, but it will give you an idea of what 500pf sounds like as a bright cap.
See if it adds enough "zing" to the tone to get you where you want to go.
If it's not quite there, it's easy enough to swap in higher values like 2200pf or 4700pf.
1000pf is the JCM800 value, so you could try that too. Ceramic caps are cheap.

Ceramic caps in these values should be easy to find. See if you have an electronics surplus store nearby. Those little surplus stores are goldmines for cool old caps and resistors.
500V is fine, but a lot of guys ( including me ) think the higher voltage ones rated for 2kv or 3kv sound better.

When you're rummaging through the bins at the surplus, don't forget the value codes:
471 = 470pf
102 = 1000pf = 1nf = .001uf
222 = 2200pf = 2n2 ( 2.2nf ) = .0022uf
472 = 4700pf = 4n7 ( 4.7nf ) = .0047uf



Thanks so much for your help!
 
Yeah those look good.
But did you try 500pf yet? That may be all you need for the sound in your head.
4700pf is a cool sound, but it's pretty aggressive.
 
fusedbrain":1byhl909 said:
Yeah those look good.
But did you try 500pf yet? That may be all you need for the sound in your head.
4700pf is a cool sound, but it's pretty aggressive.

I agree. That’s why I like 2200pf....but it all depends on the sum of the amp.
 
So i tried 4700pf and it sounds awesome but just a tad too bright, thinking 3300pf, only problem is all the ceramic ones i find on ebay are either 100v or 20kv, is 20kv okay to use?
 
DragonCrestPC":19zv8jru said:
So i tried 4700pf and it sounds awesome but just a tad too bright, thinking 3300pf, only problem is all the ceramic ones i find on ebay are either 100v or 20kv, is 20kv okay to use?

20kv :shocked:
That thing will probably be the size of a dinner plate :LOL: :LOL:
OK to use if you want, but are ya sure it's not 2kv?
 
panhead":gnz6ejcc said:
Bright cap is out of the circuit after 3-4 on the dial
I see this a lot.
Mostly in SLO threads re: the Warren Haynes mod.
My ears tell me it's not totally accurate.
On all the amps I've owned / built that have a 1000pf - 4700pf bright cap on the gain pot, rolling the pot around from 6 -9 you can still hear an eq sweep in the high end.
At "8" on a 1meg audio taper pot, the resistance through the pot is still around 250k - 300k.
That's still plenty of resistance for some treble peaking action.
YMMV
 
This is an interesting thread for me personally. I own a 2006 Germino Lead 55 and always thought it sounded a bit dark compared to the genuine article. I emailed Greg around that time and he informed me that he not only recently changed the cosmetics, but a few small values as well - one was the addition of the bright cap. He was kind enough to mail me the parts which I never installed unfortunately. If I am not mistaken, he stopped installing the bright cap shortly afterwards. Anyway, I will continue to watch this thread to see how the OP makes out with his Headroom 100.
 
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