What makes DSL lead 1 to lead 2?

[johnnyeggz]

The volumes are the channel volumes and sw1 switches between clean and ultra and sw2 is the mid scoop function.

 

[Micky]

Which vol is which?
SW1=Channel
SW2=Tone Shift

 

[johnnyeggz]

Vr2 clean vol
Vr4 ultra vol
Sw1 channel
Sw2 mid scoop
Sw3 resonance

 

[chadjwil]

OK Johnny, I got something for you. To make that Lead 2 channel match the Lead 1 of the original DSLs all you need is three resistors...but unfortunately it looks like to do it right you'll need to pull the board and probably buy two new caps. Here we go.

Somewhere near the V1 socket there should be an empty space labeled R82. Stick a 150k 1/4 or 1/2 watt resistor in there. You can monkey with that value a little to taste if you like but the older drawings call for 150k. I would only do this if everything else we do here gets you in the ballpark though. The real tonal stuff is what follows here.

C34, also in that area, you will need to pull the ground side of that cap and add a 10k resistor. This is the main reason you'll need to pull the board and most likely buy a new 1uF 100V electrolytic cap. To do this right you have to pull the ground side of that cap, solder the 10k resistor to the lead that you just removed and solder the other end of the resistor back into the hole that the cap lead came out of. If you're lucky there might be enough of the leads exposed to be able to unsolder and do all the work from the top of the board, but don't be surprised if that's not the case.

And finally, C75 (470pF 100V). The drawing calls for a 10Meg resistor to ground in exactly the same fashion as C34 above. However...since 10Meg is a VERY large resistance (virtually an open circuit) you could probably get away with just clipping this cap out of the circuit. You might not like the result but you can always go back and fix it later.

That's it. If I missed anything I would hope that someone chimes in...you're not gonna hurt my feelings.

Hope this helps get you where you wanna be Johnny!

EDIT: You might want to try just leaving C75 alone first. Its a tone shaping cap and you might like the way it sounds as is

EDIT2: The value of R82, I believe, should just increase or decrease the distotion level if you decide to experiment with that value...I think...proportionally with the value change, i.e. higher value = more distortion and vice versa. I would start with small changes as it may effect other characteristics of the circuit or valve itself.

 

[chadjwil]

Just my opinion here, but I really think that the resistor to ground after C34 (combined with adding R82) is gonna be the thing that makes the biggest difference for you. If you're feeling experimental, try just adding R82 first and checking it out, then ad the 10k to C34 and give us your opinion.

 

[chadjwil]

Dammit, one more thing. I would use at least 1/2 watt resistors for all of them. I know I said 1/4 should work but after thinking about it I would go with beefier parts.

Also, the schematic I have (thanks Micky) of your amp is a rev 4 circuit. If your board isn't rev 4 there's no guarantee that the component names will be the same. If that's the case don't despair, we can still get you there but we'll have to make a few resistance measurements just to be safe.

 

[Micky]

I would go about it one change at a time, starting with R82 (not fitted).
Maybe that will get you close.
What speaker(s) are you running this into anyway?

 

[johnnyeggz]

Thanks Chad and Micky!
I'll get the parts n have at it!

 

[johnnyeggz]

I would go about it one change at a time, starting with R82 (not fitted).
Maybe that will get you close.
What speaker(s) are you running this into anyway?

I'm using a 112 g12h30 70th....

This is my small room /around the apartment set up.

So...
150k to empty R82
10k from - of c34 to where it was.

Leave the rest alone.

 

[chadjwil]

I would agree with Micky, just try one at a time starting with R82. I mean, I'd buy all the parts at once, even the extra caps that you may not use...it's better to have the extra $2 worth of parts and not need em than have to buy then later and pay 10 bucks to have them shipped!

R82 should just decrease the overall distortion level and allow you to turn the gain knob up to a more useable level. If that's all your really after then that might just do the job by itself. The other mods are more "character" type stuff. Clipping out C75 should (if I'm not mistaken) brighten it up a good bit and the C34 portion changes the flavor of that stage a bit as well. Those you can add or remove according to your taste.

Also, make sure you take the time to find out which leg of those caps are connected to ground so you don't add the resistors to the wrong side...it makes a difference.

 

[johnnyeggz]

That's how I'll do it.
Thanks again.

 

[Tüßermensch]

Wilder said in an old thread.

"If you're referring to the 150K resistor that gets strapped across the outer legs of the Gain pot in Lead 1 mode, actually that resistor effectively reduces the value of the Gain pot from 1M to 130K, which loads the output of the first stage output, and in turn reduces the drive signal level to the 2nd stage. Switching to Lead 2 removes that resistor from the circuit, making the pot a 1M again, which reduces the loading of the 1st stage output and therefore increases drive signal to the 2nd stage in Lead 2."

Now if we can figure out how to apply that to the DSL 15, then we would have lead1 instead of lead2.

Hello,

it is more complicated than this one when analyzing the composite ac load not to mention more changes with this switching in function in the real amplifier. If we pretend just this scenario is correct with the 150k which means we are pretending just this is the only thing that hased been changed (it is not but we are just in pretend time) frequency response is altered, and as such composit ac loading! drive signal is only reduced in certain frequencies, Gain is still full erect for the high ones, well do much as this occult loading allows. If we hased been talking about simple DC, or AC without the added time factor of the shelving filter, than this statement quoted is correct, but it is not the case in this one it is more complicated

-Heinrich

 

[johnnyeggz]

Hello,

it is more complicated than this one when analyzing the composite ac load not to mention more changes with this switching in function in the real amplifier. If we pretend just this scenario is correct with the 150k which means we are pretending just this is the only thing that hased been changed (it is not but we are just in pretend time) frequency response is altered, and as such composit ac loading! drive signal is only reduced in certain frequencies, Gain is still full erect for the high ones, well do much as this occult loading allows. If we hased been talking about simple DC, or AC without the added time factor of the shelving filter, than this statement quoted is correct, but it is not the case in this one it is more complicated

-Heinrich

I did some reading,and adding the 10k to c34 is probably a big part of it.

 

[Tüßermensch]

Hello again

Micky was very nice to send a circuit plan in my email. If i am to assume it is to match your amplifier This is what hased to be done.

R14 - 220k
C58 - 2n2
R82 - put in 150k
C75 - cut out
C34 - cut out

Regard

-Heinrich

 

[Tüßermensch]

I did some reading,and adding the 10k to c34 is probably a big part of it.

Hello again

I am not so confident to what you are in reference about. If you are talking of r21 and the c13 in the 2000, it is one difference between red mode yes. R21 is one equivelant of ridding c13 only in a way to avoid audio pop by keeping charge.

-Heinrich

 

[johnnyeggz]

Now I'm confused.

 

[johnnyeggz]

Does the C34 cathode bypass get a 10k added in series or snipped?

 

[Tüßermensch]

Does the C34 cathode bypass get a 10k added in series or snipped?

Hello again,

Adding one 10k in series in this circumstance since 10k is very large when comparing to 1k8 it will bring the same result as cutting it out. Cutting it out is most easier as it should be apparent now.

You can give to yourself a partial boost by reducing this 10k to smaller perhaps 4k7 or lower, however the lead 1 you hased asked about is equal to no bypass

-Heinrich

 

[johnnyeggz]

Hello again,

Adding one 10k in series in this circumstance since 10k is very large when comparing to 1k8 it will bring the same result as cutting it out. Cutting it out is most easier as it should be apparent now.

You can give to yourself a partial boost by reducing this 10k to smaller perhaps 4k7 or lower, however the lead 1 you hased asked about is equal to no bypass

-Heinrich

Gotcha.

 

[johnnyeggz]

Ok put a 100k and 47k in series (didn't have a 150k,figured its close enough for RnR) in R82,wayyyy better,wayyyy less hum.
Lost some bass ,but just lowered the treble and presence.
Clearer tone and now I'm riding the gain at 11:00,can get crunch at the lower settings.

Now
What should I expect by
A- snipping c75
B- snipping or adding 10k resistor in series to C34