mods on a jcm 2000 tsl 100?

[spiderman2812]

I have been doing a little reading but can't seem to find out anything. Okay I've read that there is a capacitor/ low pass filter mod that you can do by coming off of a pre amp tube and taking it to ground i think that they say will smooth out your distortion and give you more bass and get rid of the buzzy distortion on the crunch and lead channels of the amp. I would really like to look into this i play mostly blues and i like that crisp sound and for this reason i rarely use those channels. If anyone could help out or point me in the right direction it would be greatly appreciated. Thanks, Kevin

[spiderman2812]

This came from geo effects website anyone got an idea for doing this to a tsl 100 head??
(have a smoother, less buzzy distortion?
Use a lowpass filter somewhere inside the amp in the signal path to cut higher harmonics; perhaps a capacitor to ground from the final preamp tube grid or plate -or-
Use series grid resistors to cut the high frequencies in and after distortion stages
Use a lowpass filter after the amplifier and before the speakers to cut out some of the higher overtones. )

[Ray Ivers]

Putting a 390pF cap across R1 on V3 on the 'Circuit Diagram' TSL100 schematic page, and a 47pF cap across VR2 on the "Overdrive Channel/Front Panel PCB' page should work well. Both these caps work as a team, greatly reducing fizz without killing the 'good' treble you want to keep, especially for live work.

This is a 12dB/octave low-pass filter starting at roughly 7.5kHz; using different cap values can slide this frequency up or down if needed, but the 7:1 cap proportions should remain constant for 12dB/octave filter performance.

Ray

[spiderman2812]

Thanks for the info. I recently found this on diystompboxes.com and was wondering if this works on a distortion pedal would it also work on the volume pots on the crunch and lead channels of the amp?

"Refine" your pedal and smooth the tone out




A Jake Nagy special! Put a smallish value capacitor on the output lugs of your volume pot (from signal to ground) to clear up the high end "buzz and hash" from your pedal and give it instant smoothness!

Try different values from 220pf to .0015uF or even larger values depending on the amount of high frequency content you want to remove.

[spiderman2812]

Also i was wondering what percent and voltage caps you would recommend? would 5% at 100v be good say at 1/4 watt?

[Ray Ivers]

Kevin,

47pF: Mouser part number 5982-15-500V47
link: http://www.mouser.com/search/ProductDetail.aspx?R=CD15ED470JO3virtualkey59850000virtu alkey5982-15-500V47

390pF: Mouser part number 5982-15-500V390
link: http://www.mouser.com/search/ProductDetail.aspx?R=CD15FD391JO3virtualkey59850000virtu alkey5982-15-500V390


Ray

[spiderman2812]

Thanks so much for the help ray i really appreciate it! I'll let you know how the mods turn out thanks again, Kevin.

[spiderman2812]

Hey ray just so it's clear here's a pic i made tell me if this is what you mean by across. Thanks. Kev

[Ray Ivers]

Kevin,

Yes, exactly correct on both of them.

Ray

[simon074]

Ray, Mercury Magnetics sells a choke for the TSL 100. Have you ever heard of any one putting one in? And where would the wires go? Also, with putting the 47pF cap across the outer lugs of the pot? Thanks.

[Ray Ivers]

Simon,

I've only added a choke to one Marshall - the 6100 30th Anniversary head. FWIW, I was happy with the results.

As far as wiring goes, I would remove R71 on the 'Circuit Diagram' schematic page, and connect the choke wires to the PCB pads that resistor used - either wire to either pad.

Kevin's diagram shows how to connect both caps - the 47pF goes across the outer lugs of the pot, as you posted.

Ray

[simon074]

Ray, Thank you very much. I'll try that.

[AdmiralB]

I've put chokes in DSLs, I think the TSLs use the same basic boards. Here's a shot of a DSL 50 with a Hammond 158M.

http://r.clear.home.insightbb.com/choke.JPG

[spiderman2812]

Hey ray thanks alot i put the caps on the lead channel and it sounds great no more fizz!! would the same principle apply to the crunch channel with the 47pf cap on vr2? And if i was to do it to the crunch channel would i need to use another 390pf somewhere other than r1 on vr3? Thanks a million!!
Kevin

[Ray Ivers]

Kevin,

I'm glad it worked out for you! For the crunch channel... well, after spending over an hour trying to chase this thing out, my suggestion would be to try just the 47pF cap across VR2 on the 'Crunch Channel' schematic page (as you posted) and see how that works; that definitely won't cut treble on your clean channel, and hopefully the lower-gain crunch channel won't be generating as much fizz and one cap will be enough. You could always add another 47pF cap in parallel with this one if you need more fizz reduction.

Ray

[spiderman2812]

Thanks Ray I really appreciate it. Sorry for being a pest!! Thanks for spending sometime and helping me out I think you're the only person out of several forums that was able to help. Thanks again!!:D

[Ray Ivers]

Kevin,

No problem at all - I usually have at least some problem reading these newer Marshall prints. I got lucky right away with the gain channel, but until I can trace CON 3/pin 3 on the 'Crunch Channel' page to a believable destination (references to 'rat's nest purposes' always making me a little nervous ;)), I'd rather leave you with a little remaining fizz than possibly screw up the sound of another channel.

I've heard your same complaint a number of times about these amps, and I've noticed the fizz myself on the few I've played; hopefully this info may help someone else out too.

Ray

[BobbyBizzle]

Do these mods apply to the TSL 60 Head as well? I'm looking to swap out my transformers because I bought the amp on ebay and I think they were changed. They have $20 price tags on both of them and say drake's transformers. I don't believe that these are the old Drake transformers used in the 60s (???), but I think they would cost more than $20 bucks each... Any one know what transformers to pick up for the TSL 60? Lookin at the mercury magnets but they are really pricey...

Since my amp is completely ripped apart, I might as well try this mod as I've noticed a little fizzing going on. These are mods are easily reversible correct? So yea if you guys know if this mod is compatible or what the deal is with my transformers let me know!!! Thanks!

[Enzo]

Are you sure these are price tags and not lot codes?

Seems pricey to swap out transformers just because there are stickers on them. Does the amp work with them?

[BobbyBizzle]

They are definitely price tags. The amp works but just doesn't sound like the ones in the music stores. Sounds thinner than those ones...

[jctaudiodesigns]

Can someone tell me what are the little square caps that are being used in this amp, and what kind of quality are they?

[pooka]

could you do the same thing to a jcm 2000 DSL? in that case, where?