My Marshall DSL40c is Woke

[Bocc69]

Did some way over due tweeks to my DSL40c. Simple stuff, greatly needed. Haven't been happy with the amp for some time.

Changed out the Seventy/80....put in Celestion G12H-75 Creamback.




Even though I was changing tubes, I decided to Bias the amp first.
I put in the speaker, then bias the amp. I just wanted to see how far off it was before I made any tube changes. Glad I did...I had been putting it off. I didn't check the plate voltage, but it seems most people aim for 38ish. So, that's my target. (Expert no, guess sometimes have to)

Right side wasn't to bad at 39.2. But the left side was way over at 54.1, and it took a while to get them both in the same ball park.
I finally Got them where i wanted (38.1 - 38.2)...then plugged her in. Wow, sounds great. Very noticeable difference. Love what I hear, but there was still a slight "tinney" sound. I think one of the power tubes was on its way out.



All new tubes. Nothing elaborate, just some Tung-sol. I got mixed reviews on these, but have to start somewhere, soooo ... Went thru the bias again. Obviously it was way off, but so much easier to set then previous attempt. I knew something was fixed. Kept it in the high 37 mark this time.





Plugged her in, classic bar chord ......Strum Strum Strum. WOW, I'm happy.

Really love what I'm hearing. Not ALL highs like previous. Much warmer, especially low chug chug chugging. The notes are less mushy and more pronounced. Need to get some hours in and break in the speaker. I'm really liking this amp now. Can't wait to crank it.

 

[aon]

That's a nice looking shop.

 

[Bocc69]

That's a nice looking shop.

Thank you aon.
It's a '63 original.
Actually, I've been restoring the place for the last 2 years. For some strange reason, last on the list is my Jam room and my shop. Hummm, why is that?

 

[Don O]

I put the same speaker in my DSL40 a while back. Now ya got me wanting to go check the bias.

 

[Bocc69]

Now the question is.... to clip or not to clip?
That c19 is a little bugger ain't it. Heating it and pulling a leg out is probably the way to go. I may just leave it..... I'm liking the amp rite now. I am curious though...

 

[Don O]

I’d lift a leg and solder 2 wires and put a small toggle switch on the back of the chassis. C19 in, C19 Out.

 

[Bocc69]

I’d lift a leg and solder 2 wires and put a small toggle switch on the back of the chassis. C19 in, C19 Out.

Well, that's an interesting idea? Is that doable? Which side of the C19 would the switch go? guessing, it doesn't matter?

My thought was pull a leg out, if I hate it put it back. however now, if i kinda like it, do a switch.

 

[Bocc69]

I put the same speaker in my DSL40 a while back. Now ya got me wanting to go check the bias.

Highly recommend the bias. Quick an easy job.....and, I thought fun.

 

[Don O]

Well, that's an interesting idea? Is that doable? Which side of the C19 would the switch go? guessing, it doesn't matter?

My thought was pull a leg out, if I hate it put it back. however now, if i kinda like it, do a switch.

Heat one side of the cap and lift the leg. Doesn’t matter which side. Solder 1 wire into the PCB hole and then solder and shrink tube the raised cap leg. Run those 2 wires to the toggle switch. You are simply completing the original circuit when the switch is closed and removing the cap from the circuit when the switch is open. Keep the wires as short as possible.

 

[Don O]

Highly recommend the bias. Quick an easy job.....and, I thought fun.

Yea, might do it today after a few chores.

 

[Ramo]

Now show us how that amp can unleash hell of chug!

 

[syscokid]

I finally Got them where i wanted (38.1 - 38.2)...then plugged her in.

How did you match the bias? Does the amp have a pair of bias adjusting pots?

 

[Bocc69]

How did you match the bias? Does the amp have a pair of bias adjusting pots?

Yes sir. Easy deal.

I got nervous once....I ran out of adjustment room and still needed to raise the value. Then I remembered that one side affects the other. I lowered the other side first, then went back and forth.

 

[syscokid]

Yes sir. Easy deal.

Nice... . My V2 Caldera amp is designed with a pair of trim pots. I think all push-pull type of amps should be designed this way...

 

[Bocc69]

I think all push-pull type of amps should be designed this way..

So true. I remember saying when I was done "...and, why didn't I do this earlier?" It was just so easy.
Just need to take your time and be careful.

 

[Don O]

I’m going to use 2 meters when doing it so it will be easier to dial it in. Did not get to it today.

 

[Bocc69]

I’m going to use 2 meters when doing it so it will be easier to dial it in. Did not get to it today.

Great idea. That will surely make the job easier... as long as you can get 2 clips on the center post. I'm sure you have that covered though.

 

[Don O]

Great idea. That will surely make the job easier... as long as you can get 2 clips on the center post. I'm sure you have that covered though.

One clip on center post and 2 clips on the other end of that.

 

[syscokid]

I’m going to use 2 meters when doing it so it will be easier to dial it in. Did not get to it today.

Make sure they're matching meters...

 

[Jethro Rocker]

Speaker change is huge on that amp. Try lifting one leg on C19 then play and see. I did it with mine. If you really like it, leave it. If not, put it back. If you like it both ways, mount a switch.