The Vesperado Mod thread for the JCM2000 TSL-100: Finished

[Vesperado]

Even better:

(Superceded.)

Changes made:
- rebalanced the FX Loop mixer for the CL channel
- readjusted the Bass cap value for tighter cF
- readjusted R12

NB: I play chiefly with my Single Cut. However, my ASAT produces some extra bass. 100n would likely suit that axe best. Nevertheless, switching Main C12 (with the parallel 3u3) to the smallest value takes care of that. 73n is an improvement over 68n in that it wards off the "woofy-ness", especially with the Deep engaged. It also seems to play better with all three toggle positions for the hi-pass input cap.

Overall, the amp is ready to gig now.

 

[Vesperado]

I have decided to go "full Fender" on the Green channel. I know.

(Superceded.)

DTSC renders a plot of the two 'tone slope' values I have selected for my two-fold voicing of the Green channel:

Screenshot_20230528-220351_Samsung Internet.jpg

marshallforum.com

There is an offset of 100 cycles between the mid scoops and about 4dB in the highs or so. I max'ed the Trebs and Lows, and swept the range of the mids. The mids give me more boost over a Fender amp, given the B20K pots on the TSL. It may not look like much, but they both have audible characteristics independent of one another.

The signal's attenuation levels, surprisingly, originally set at "Main R80" and Clean R12 seem to best support Leo's specs--quite interesting. Methinks the engineer(s) took his/their design immediately from Leo. My suspicions are so because when I applied both cathode bypass caps, adjusted for 1800 ohm resistor values, I obtained the full range of the Gain pot's sweep. So it is evident that they made a compromise in the value for C12, making it far less than Leo's but much greater than Jim's, and opted to forego the cascading bypass cap, likely to escape patent law, lest they got found out. They also added the 10k ohm Bass 'floor' either because they (a) confounded its purpose and simply copied the circuit, or (b) needed to make-up the lost Gain in the low-end. I only pose this forth as that value is suspect to me, yet seen on a few of Leo's designs. An odd implementation, no doubt, especially given the lack of a Bass tone cap, where the Bass would default to the Mid tone cap, and rather high for this circuit. I am leaning towards (b), because we cannot discount the fact that they adduced, unconventionally, an additional gain stage, albeit in a most unconventional place: a positive lobe for the other channels. With all that low-mid Bass content, they must have been prompted to boost the highs so as to cut through the mix, and likely why they opted for Main C24. Unlike their peculiar elections, Leo's circuit provides for plenty of "top", and they employed his 100k tone slope value, so one could get an idea how much make-up Gain they had to seek for from somewhere. Have a look at Main R17/34 as well.

With Leo's circuit implemented on the TSL, there are no Gain-loss shenanegans, no woofy Bass, no clipping saturation, &c. &c. The tone is PLENTIFUL. Paralleling a 21u pol. can (as I have outlined) across Main C12 lands us in the proper range, that infamous Fender territory, where Lows are punchy, mids duck out of the way, and the highs are sweet, jangly, chimey, and pleasant. But to get Leo's signature tone, something must be done at Main C24. That is at the present time, a conumdrum, for we CANNOT simply have the 21u pol. can share a point of contact with any other cap at the Drain of Main TR2; this will cause feedback with stages 1 & 3, or uncontrollable oscillation, once the drives are engaged. I have a temporary solution which I worked out, outlined below:

20230528_163824.jpg

marshallforum.com

That is, Switch #11.

It's not perfect, but it will tap into Leo's signature tone. It switches in an 11u pol. can at Main C24. It, along with the 21u pol., sound great in all three of my clipping configurations: symm.(1k8)/asymm.(2k6)/asymm.(2k6)+C9(66p). Only caveat is, it must be switched back out PRIOR to engaging the drive channels, else feedback develops. So, it works for jammin' at home, but will need to be rectified before jammin' with friends. I have purposely left it out of the drawing. I have FET2 eyed for the task, however, I am unsure whether it would be permissible to have one FET to close to Ground and the other open the Ground connection, without upsetting the switching line. Provided it doesn't (and I need an answer) then finding a suitable equivalent which opens rather than closes would be the next step.

Tone-wise, C24-11u pol. mellows out the 'excited' highs and 'punchy' lows in that it boosts the mids. Its a classic but creamy tone--works great with a TS9 and neck pup. Very reminiscent of SoCal vibes if anyone is familiar with fish tacos off of the 101...anyways, retro 50's, yeah.

So, with the new switch, I have 64 combinations with the Cleans on the amp. I am happy to report that the 235p (Peaker V) plate bypass complements its sparkle for the better. I am content with one cap at that location, the other value picked the ears too much, so its now a SPST. The switches are detailed as follows (from left to right):

20230528_163558.jpg

marshallforum.com

Peaker IV select/OFF
Peaker II select/OFF
OD Coupler select
Grid Leak Stages 3/4 select
Input Hi-pass select
Input Hi-pass ON/OFF
OD2 Cathode Bypass select
CL Cathode Bypass Stage 2 ON/OFF
[stby] Peaker III select/OFF
[stby] Peaker V ON/OFF
[stby] Symm.-Asymm. select

Off to resolve (I hope) that one singular caveat...

 

[Vesperado]

Updated and improved:

(Superceded.)

I have departed from Matt's presence cap value for the drives. Its good for modern tones with thick mids, but I was itching for more Plexi vibes, so that's that.

Clean reverb decay is now a tad reduced to better suit the increase in Gain with the second stage cathode bypass cap.

Speaking of that, I rerouted S2 CBC switch to ground, a temporary solution, so I thought, until I switched the channel. I recall testing out large values for a CBC in stage four of the drives a while back, but gave up on that. Seems like 11u is a nice fit. I tried some others, and ended up on 15u as a second, more bass heavy option. Anything above 20u gets fuzzy down below. The 15u value also suits the Clean in that it pushes more low-mids/bass. Different, but interesting. At minimum I have the option for Fender cleans, and some extra flare for the Drives. Cascading the cathode bypass gain boosts in OD2 is interesting. Not quite a resonance effect, more like a 'second push' on the tone. Gain knob needs to be dialed back to compensate. Approaches a stadium-like tone.

The 1.2u value for the input hi-pass has been retrograded to the 2u value to better suit S4 CBC of the Drives.

Other than that, revamped switching sheme is as follows:

20230528_163558.jpg

marshallforum.com

Peaker IV select/OFF
Peaker II select/OFF
OD Coupler select
Grid Leak Stages 3/4 select
Input Hi-pass select
Input Hi-pass ON/OFF
OD2 Cathode Bypass select
CL Stage 2/OD Stage 4 CBC select/OFF
[stby] Peaker III select/OFF
[stby] Peaker V ON/OFF
[stby] Symm.-Asymm. select

 

[Vesperado]

I kick myself for not tinkering around with the tone stack sooner:

(Superceded.)

Orange shows my 1987-ish mids-sweep, and the white the NEW Tone-Shift stack. The graph doesn't look much on paper...

Long gone are the JCM2000 tone stack values!

HELLO MARSHALL!

(Superceded.)

WHERE have YOU been ALL of my LIFE??

WHOOOHOOOOOOOO

 

[Vesperado]

Aye caramba:

(Superceded.)

Tuned up my voicing for the drives.

 

[Vesperado]

Currently need to order some parts. Once I get them, I will publish the changes up here. So far, the Tone-shift modes have been completely revamped, as well as some particulars in the pre. Its miles ahead of where it was a few days ago, almost like a completely new amp.

 

[Hackingthestrings]

I just bought a one owner, all original never touched inside 2004 TSL 100 today and am going to run it on my Orange PPC112. Yep, gonna prob need tubes (they are the original!) and a power brake but I snagged the JCM off Craigslist for $600, plenty of room for tubes and the Dr. Tube bias kit. Will worry about the power brake later. Is there anything else that would be considered a must do for reliability? Thank you for the hand.

 

[Vesperado]

I just bought a one owner, all original never touched inside 2004 TSL 100 today and am going to run it on my Orange PPC112. Yep, gonna prob need tubes (they are the original!) and a power brake but I snagged the JCM off Craigslist for $600, plenty of room for tubes and the Dr. Tube bias kit. Will worry about the power brake later. Is there anything else that would be considered a must do for reliability? Thank you for the hand. View attachment 131378

For reliability? Yes. There are a few things that ought to be addressed. How much money and time are you willing to spend to have a reliable TSL would be the question.

The updated drawings will be posted up here in a few days where you shall find all the points addressed regarding reliability.

Basically all mainboard aluminum caps need replaced/upgraded (good to upgrade while replacing), upgrade the Power Transformer, acquire spare fuses for the country/area, for starters, then a few modifications, one for the 16 ohm speaker jack, one or two for the switching circuit, plus several others. I don't have experience with the "bias kit", but the method which I have adopted runs a solid bias scheme, plus some fail-safes.

You can follow this thread in anticipation for the updates.

Cheers

 

[Vesperado]

LAST ONE:

TL10-6x-0x Vesperado Mod FINAL.pdf

Remove 47k. Accutronics USA 4BB3C1D Two-Spring Tank, fully shielded and EE to chasis for EMI/RFI rejection. A short tank would provide for less "decay". Remove. NJM2121D: provides wider bandwitdh and better slew rate. **. Remove. NB: Some boards are fitted with 220k at R1. 240k. 182k. 100u. C13...

docdro.id

Many improvements since last. Done all I've could. Throwing the towel in on this one, gents.

 

[Tatzmann]

LAST ONE:

U SURE?

 

[lesexypaul82]

Do we get get a before and after sound comparison?
If this is the last update.. Where do i start with mine? Do i get your last update and does it have all the mods.. or do i have to go back to the startand find each update do it before doing the next?

 

[Vesperado]

Do we get get a before and after sound comparison?
If this is the last update.. Where do i start with mine? Do i get your last update and does it have all the mods.. or do i have to go back to the startand find each update do it before doing the next?

The link provides the final update. Everything is there. To answer your other question: I am not planning to upload any audio clips. Feel free to complete as much, or as little, of the mod as you see fit, however, I recommend the lot.