Marshall TSL100

[JoeRocks]

At the risk of sounding totally ignorent, if you had to guestimate, what percentage of tonal improvement would replacing the resistors make to this amp?

[JoeRocks]

Should I only replace R67,R68,R69 and R77 or are there others too?

[JoeRocks]

Do you know what voltage the resistors should be.

[jamesmafyew]

At the risk of sounding totally ignorent, if you had to guestimate, what percentage of tonal improvement would replacing the resistors make to this amp?

I honestly can't say. Mine is a later model TSL that had the updated mainboard (better board materials and all metal film resistors, correct grid blocker values). I thought it sounded pretty decent bone stock. I've had it modded for a long time now. I just remember playing someone else's older TSL in Australia and being disgusted by the stock sound --- I thought, "I don't remember mine sounding this bad before I modded it." I had even brought my own tubes and biased it myself. I played another loaner TSL in Greece this past summer and it too was older and sounded terrible. Who knows --- try it, it's cheap.

[bluesfreak]

Just take 1/2W or 1W metal film resistors, they can handle the voltages. for the grid stopper I usually use 1 or 2W types depending what I have on stock. Going down from 220k to 5.6k will remove a blanket from the amp, it will sound much more open and responsive, with 220k it will be dull. Back then the went to 220k as the available tubes did blow all the time with 5.6k due to only very bad quality available...

[Dave Curtis, dB AudioTech]

Just take 1/2W or 1W metal film resistors, they can handle the voltages. for the grid stopper I usually use 1 or 2W types depending what I have on stock.

Stock was 1/4w. 1/2w is fine. The leads on the 2W I have won't fit through the holes...

Going down from 220k to 5.6k will remove a blanket from the amp, it will sound much more open and responsive, with 220k it will be dull. Back then the went to 220k as the available tubes did blow all the time with 5.6k due to only very bad quality available...

Perhaps the tubes they were sourcing were junk (like the early board material; which caused tube failures even with 220K). Or perhaps they thought the tubes were bad because of the bad boards... All speculation. (BTW, good EL34s were available "back then")



I believe the 220Ks were a typo. Whoever drew the print put a 220K designation on those resistors by accident, and they were built that way. The early schematic shows them as 220K. Later revisions show 5K6. Again, this is pure speculation. Correct me if I'm wrong, but 220K is near or over the max. allowable series resistance for the grid circuit.

[JoeRocks]

We are talking about replacing the resistors on the main board. Does this only apply to the older model TSL's? Mine is a 2004 model and I'm pretty sure is has the newer style board. So I guess the question is, could I have the 220ks in there or would it have the 5.6's? It almost seems as though they had these issues on earlier model amps. I am just trying to get all info before tearing this amp apart again. Thanks.

[Dave Curtis, dB AudioTech]

We are talking about replacing the resistors on the main board. Does this only apply to the older model TSL's? Mine is a 2004 model and I'm pretty sure is has the newer style board. So I guess the question is, could I have the 220ks in there or would it have the 5.6's? It almost seems as though they had these issues on earlier model amps. I am just trying to get all info before tearing this amp apart again. Thanks.

You likely have 5K6 resistors in yours. The 220Ks were only used for the first year or so.

[jakstrait]

Joe,

I wrote the post at the site you linked to. Based both on the schematic and my experience, changing the value at VR2 does NOT affect the clean channel. On the DSL it does, but NOT the TSL. That pot is isolated to the lead circuit.

The 390pf cap across R1 on V3 WILL affect the clean channel. Essentially, when you're in the lead mode, the VR2 cap and the R1 cap each create a 6db/octave lowpass filter, giving you a 12db/octave total response curve. When in the clean channel, you still have the 390pf cap in-circuit, giving you a 6db/octave lowpass.

I would guess that you may have accidentally done something else while making the change. Try switching the 68pf cap back to 47pf and see what happens. Record the amp before and after the change, on each channel, so that you can evaluate the change impartially. My guess is that it won't fix the clean sound. You can also try removing the 390pf cap from R1, which WILL change the clean channel sound, but will also mean less fizz-reduction on the lead channel.

HI,

i am running a TSL 100 head with winged C's in the power section and a mix of JJ's and Tungsol 12AX7's in the preamp, sounds great but maybe a just a touch too much fizz in the lead channel.

wondering if just putting say a 47pF or 68pF cap across VR2 on the lead channel will sort it, and leave the 390pF off R1 so as to not affect the clean channel???