Tube Function By Position - Marshall DSL40C:

Inspector #20

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I have been kicking this around a while. I originally put a set of 7025-WA's in V1-V4 not long after I received it. Based on a recommendation from one of our TTR Gurus, I added a JJ-5751 in V1 to cut some of the 'fizzy' nature of the amp.

Now, I am contemplating a JJ-ECC83-MG in V1 and perhaps a 5751 in V2 with the 7025-WA's in V3 and V4. As I understand from the schematic, the DSL40 tubes are laid out like this:

V1 and V2 are the gain stages,
V3 is the last gain stage and cathode follower
V4 is the Phase Inverter

So, how would my proposal tube layout appear to you more educated amp gurus???
 
The situation with Eurotubes is that they only sell JJ's. I'm not really crazy about JJ's. Their EL84's are decent. Their E34L (Variant of EL34) is a fantastic sounding tube, but I don't know how reliable this one is. Definitely not impressed with their 12AX7's.
 
Interestingly, with this tube combination, the DSL40C settings - when set totally by ear - almost mimicked the VS265 settings identically. The VS265 is never adjusted appreciably from its rehearsal/performance settings shown.

Zoom in to see the dial positions (in red characters) and notes:

VS 265 Settings.jpg


And a shot of the DSL40C post tube swap:

DSL40c Settings.jpg

Interesting points between the two amps:

1997 Valvestate VS265 2 X 12 Emminence Gold Backs

The VS265 has a 'Contour' control knob which functions to scoop the mids. Since I accompany a very mid-rangey bass in this group, I tend to fatten my tone a bit. The 'FX Loop MIx' also functions as a slight volume and mid boost when engaged, even with nothing in the loop.

With the mids cranked to '10' and boosted slightly with the FX Mix, I am able to roll some of the mids off with the Contour, which has a 'coloring' effect. It's subtle, but seems to add more low frequency to the mids without affecting their ability to cut through.

The 'Power Dimension' button is designed (according to Marshall) to act like an attentuator - giving a more saturated tone at low volumes. In actual use, it functions like a mid boost.

If you crank the gain on the VS265 to '10' it never gets flubby or muddy, even with a Soviet Genelex Gold Lion 'B759' in pre-amp position V1.

2015 DSL40C 1 X 12 WGS 55Hz Reaper

The DSL40C does not have a 'Contour' control, but allows highs (Presence) and lows (resonance) to be boosted or cut to suit your tastes.

Notice that mids are fully boosted and then 'colored' with the 'Tone Shift' which trims some of the 'edge' off the mid frequencies, but doesn't add any muddiness.

'Lead 2' is always 'On,' which gives a mid boost and a more pronounced gain effect. Switching between Lead 1 and Lead 2 is dramatic. Lead 1 sounds thin in comparison. Lead 2 is thicker, harder-hitting in general, with a much more aggressive gain effect for the same amount of knob movement in Lead 1.

So, if you consider the effect that is being used on each amp, the settings - when set totally by ear - are nearly identical and the tones are very similar.

If you increase the gain on the DSL40C above about '5' on the dial (12 O'clock) the tone gets muddy and undefined. The gain on this amp - at least on this one I have here - is totallu unuseable on 'Lead 1' above '7' (dial setting) and above '5' (dial setting) on 'Lead 2.'

The most noticeable difference between the two is where the two amps score on the aural spectrum.

On the VS265 - Think of Mustaine's rhythm tone on 'A Tout Le Monde.' The twin 12" speakers really add depth and presence to the tone. Sounds like a half stack when recording direct out.

On the DSL40C - Think of Angus Young's tone on 'Let's Get It Up.'

The tones are very usable, but in very different ways.

All the 'muddiness' that I was attributing the the WGS Reaper 55Hz was actually the result of too high a gain setting!!!!!!!
 
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Robert, on my DSL 15, esteemed forum member, Goldmember recommended a JJ ECC823 in V1.
It's a special little beast.
It cuts gain on the red chanel by a certain percent, thereby reducing the harsh & fizzy edge, but leaves the green chanel unmolested.
Here's the official text...

"The JJ ECC823 is wired in reverse of the ECC832 / 12DW7. In the ECC823 the first half of the tube (pins 1, 2 and 3) are the high gain 12AX7/ECC83 spec (gain factor 100) and the second half (pins 6, 7 and 8) are the low gain 12AU7/ECC82 spec (gain factor 20). This ECC823 can be used in amps like the Mesa DC series in V1 to keep the clean channel stock and drop the gain down in the drive channel."

Believe me, it worked wonders in my DSL 15, which is very similar to it's rowdy sibling your DSL 40.

Here's a link to the tube.
JJ ECC823 Preamp Vacuum Tube | TubeDepot.com
 
Robert, on my DSL 15, esteemed forum member, Goldmember recommended a JJ ECC823 in V1.
It's a special little beast.
It cuts gain on the red chanel by a certain percent, thereby reducing the harsh & fizzy edge, but leaves the green chanel unmolested.
Here's the official text...

"The JJ ECC823 is wired in reverse of the ECC832 / 12DW7. In the ECC823 the first half of the tube (pins 1, 2 and 3) are the high gain 12AX7/ECC83 spec (gain factor 100) and the second half (pins 6, 7 and 8) are the low gain 12AU7/ECC82 spec (gain factor 20). This ECC823 can be used in amps like the Mesa DC series in V1 to keep the clean channel stock and drop the gain down in the drive channel."

Believe me, it worked wonders in my DSL 15, which is very similar to it's rowdy sibling your DSL 40.

Here's a link to the tube.
JJ ECC823 Preamp Vacuum Tube | TubeDepot.com

Cool, Man...Thanks for the link!!!
 
Robert, on my DSL 15, esteemed forum member, Goldmember recommended a JJ ECC823 in V1.
It's a special little beast.
It cuts gain on the red chanel by a certain percent, thereby reducing the harsh & fizzy edge, but leaves the green chanel unmolested.
Here's the official text...

"The JJ ECC823 is wired in reverse of the ECC832 / 12DW7. In the ECC823 the first half of the tube (pins 1, 2 and 3) are the high gain 12AX7/ECC83 spec (gain factor 100) and the second half (pins 6, 7 and 8) are the low gain 12AU7/ECC82 spec (gain factor 20). This ECC823 can be used in amps like the Mesa DC series in V1 to keep the clean channel stock and drop the gain down in the drive channel."

Believe me, it worked wonders in my DSL 15, which is very similar to it's rowdy sibling your DSL 40.

Here's a link to the tube.
JJ ECC823 Preamp Vacuum Tube | TubeDepot.com

Legend says that Stevie Ray Vaughan used a 5751 in V1 (30% less gain than a 12AX7) to alter the characteristics of his amp and suit the tone he wanted. I used a 5751 in V2 which takes the edge off. I never use the green channel for overdrive, so I didn't consider how a tube swap might affect it...
 
Legend says that Stevie Ray Vaughan used a 5751 in V1 (30% less gain than a 12AX7) to alter the characteristics of his amp and suit the tone he wanted.
Yes he did, but only on his old Fender amps. I don't think he did this with his old Marshalls and his Dumble Steel String Singer. AFAIK, using a 5751 in a high-gain style amp really messes with the chemistry of the design. Hopefully you'll try Hackmaster's ECC823 tube in V1 suggestion, and then post your opinion. YOU CAN DO IT!
 
Yes he did, but only on his old Fender amps. I don't think he did this with his old Marshalls and his Dumble Steel String Singer. AFAIK, using a 5751 in a high-gain style amp really messes with the chemistry of the design. Hopefully you'll try Hackmaster's ECC823 tube in V1 suggestion, and then post your opinion. YOU CAN DO IT!

At present, I am limiting my experiments to only those tubes I have on the shelf, so my selection is somewhat limited. The JJ ECC83-MG in V1 was an excellent move. Likewise, the JJ-5751 in V2 was also an excellent move and the tone produced by these tubes in these positions was quite dramatic when compared to the JJ-5751 in V1 and the 7025-WA in V2.

Now in V3, I have read that you want to avoid long-plates - like the 5751 - because of potential feedback issues, so I opted for a Marshall branded ECC83S in V3 and a standard 7025-WA in V4. Power tubes are a matched pair of Electro-Harmonix EL-34's, so nothing dramatic here.

Again, the big surprise was how the more I turned up the gain, the worse the DSL40C sounded!!!!
 
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