# ygm 4 filter cap values



## pauledc (Mar 4, 2013)

Hi all, i would like to change the original filter caps. I think my amp is from 1976-77? there are 4 Axial 40x450 in there now. the re issue is down ot 32 x450. the only Axial i can find close to spec are jj or F& t @ 30 x 500. i can get the 32x500 in the cans but since the exisitng are the axial it would make the job really easy.

I think this should be no problem and may even sound better.

Your thoughts are greatly appreciated.

Thanks

Paul


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## dtsaudio (Apr 15, 2009)

The tubestore has Illinois Capacitors [email protected] closer to what you have now.


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## pauledc (Mar 4, 2013)

Would that make it too stiff? I'm fairly new to this but its becoming addictive. 
Thanks


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## dtsaudio (Apr 15, 2009)

I don't think you'd notice the difference unless what's in there now is way off spec. If that's the case, the amp should pretty bad too.


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## parkhead (Aug 14, 2009)

47mfd would make the amp too stiff 
I use jj 32/32 cans ... 
more recently I use the jj 32/32, f&t 16/16 and a single 8mfd ... in a secret sauce formula (not what you'd think) 

this decreases the filter at each stage but adds one extra rc network of filtering 
with this setup you can dial in more headroom by decreasing the power supply step resistors (raising the pre amp voltages) 
and pick up a better distortion tone when you hit the amp hard 

to replace the axial units I still use the jj cans and clamps but bend one of the hold down tabs 90 deg so that I can bolt 
the clamp right into the spot the old filters came from ... I am sure there's a you-tube video out there of some guy doing this 

p


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## pauledc (Mar 4, 2013)

I did see that video...I also heard that guys drinks a lot and recorded the video naked!

i think i'll try the 30 30 30 30 axial and see how much hum i get...not that i'll notice when its dimed! Ya baby!

Cheers


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## pauledc (Mar 4, 2013)

I ended up going with 30/22/16/16 and a full e cap job. Wow sounding nice...much quieter that the originalls and much smaller... Still working on some tweeks to fine tune it. the volume has increased as well in a good way.

Cheers all and thanks for the help thus far!


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## parkhead (Aug 14, 2009)

pauledc said:


> I ended up going with 30/22/16/16 and a full e cap job. Wow sounding nice...much quieter that the originalls and much smaller... Still working on some tweeks to fine tune it. the volume has increased as well in a good way.
> 
> Cheers all and thanks for the help thus far!


Brilliant... it should sound amazing with that spec, good work ... way more musical 
Ive gone as high as 64 on the first B+ filter if I want more low end thump... then just drop the values to vintage fender specs like you did 

p


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## nonreverb (Sep 19, 2006)

Don't get too bent out of shape between 40uf and 47uf caps. The amp is solid state rectified and that small increase won't make that much difference.
Doubling the capacitance will and definitely going significantly smaller will as well. It's all about taste.


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## pauledc (Mar 4, 2013)

parkhead said:


> Brilliant... it should sound amazing with that spec, good work ... way more musical
> Ive gone as high as 64 on the first B+ filter if I want more low end thump... then just drop the values to vintage fender specs like you did
> 
> p



I'm still trying to get rid of the bass thump...the bass past 12 o'clock is completely unusable, no matter the treble settings. Don't get me wrong i can still dial it in, but would like to be able to use the full sweep of the pot.

Maybe i should increase the B+ filter a bit?

I've changed c1 to the recomended .01 helped alot
I've changed R10?cant remember...from 47k to 27k this helped more.

C2 padded with 470k - this is great- bright switch is now on more than not -I play a very dark sounding Pan Trini lopez copy hollow body. (neck pickup)

Anyway, other than the bass, this has turned out to be a sweet amp! Better than my old Deluxe Reverb for sure and louder.

Thanks all and this was fun learning experience!


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## parkhead (Aug 14, 2009)

pauledc said:


> I'm still trying to get rid of the bass thump...the bass past 12 o'clock is completely unusable, no matter the treble settings. Don't get me wrong i can still dial it in, but would like to be able to use the full sweep of the pot.
> 
> Maybe i should increase the B+ filter a bit?
> 
> ...


change c6 to .02 from .01 or .005 
change r9 to 100k 

this allows more bass to be pulled to ground through the tone network
r9 changes the mix of treble and bass at the output of the network (like the slope resistor on normal tone stack) 

if that's still not enough look at the output coupling caps they are .1 you can go to .02 on those 

increasing the filtering will add bass... thats is one of the reasons reduced filtering is so effective 
it removes a lot of sub harmonic garbage that just makes the amp sound bad 

check r8 3.3 meg to make sure it has a 10pf cap over it 
some later ones do not have it and are much darker 
if you need one get 10pf silver mica 


P


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## pauledc (Mar 4, 2013)

parkhead said:


> change c6 to .02 from .01 or .005
> change r9 to 100k
> 
> this allows more bass to be pulled to ground through the tone network
> ...


I nominate *parkhead *to be inducted into the *Traynor Vintage Amp Rock & Roll Hall of Fame!*


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## parkhead (Aug 14, 2009)

pauledc said:


> I nominate *parkhead *to be inducted into the *Traynor Vintage Amp Rock & Roll Hall of Fame!*


I only accept payment in broken Traynor amps and Beer ... wine too but it should be a nice Chilean red 

p


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## pauledc (Mar 4, 2013)

parkhead said:


> I only accept payment in broken Traynor amps and Beer ... wine too but it should be a nice Chilean red
> 
> p


Beer and Chilean red it is then. I drive through Parkhead on my way up to the cottage. Which of the four houses is yours?


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## pauledc (Mar 4, 2013)

I just changed c9 to 4.7uf Wow...midnight rambler all night long... Less bass, less graininess no pedals needed!


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