DSL1H with MiniStack cabinets

[scozz]

Thanks for info @santiall, and you too @fitz, much appreciated!

 

[Mitchell Pearrow]

@vonjet

To The Forum

 

[santiall]

Thanks again.

I was assuming that the 16 ohm wire would be insulated and tied off like the 8 ohm wire.
I no longer have a DSL-1, but this topic comes up now and again with various conflicting opinions.
Just trying to have a good answer when the question inevitably returns.

To the best of my knowledge, impedance mismatches in tube amps causes more stress on the transformer and power tubes than a match, but how much seems debatable.
I swear I remember someone smarter than me explaining that with a 1w amp, the power is so small compared to bigger amps, that the additional stress of a mismatch is insignificant.
If it's more a matter of tone, then I suppose that it may just be as subjective as speaker, or pickup choices.

One of the reasons I didn't keep it was because of the single 16 ohm speaker jack, and I didn't want to get into altering the amp.
I like 2 speaker set-ups and most of my speakers were, and still are, 16 ohm.
If I had known then about the 8 ohm tap, I may have kept it.

that's why I asked. The internal attenuator is designed for a 16ohm load and will present itself at approx 16ohm when nothing is plugged into the speaker outs. Replacing the 16ohm wire with the 8ohm wire will mean that the only "matched" combination will be when in full power and using an 8ohm speaker.
As soon as you engage the 0.1W attenuation you will be mismatching the output.
I mention this because people seem very worried about using the 8 ohm speaker with the 16ohm tap but one will be pretty much causing the same mismatch when exchanging the wires and using the attenuator.
It was probably me who said that 1W is such a low power that it doesn't matter but actually the same mismatch in a 100W amp doesn't matter either.

 

[vonjet]

that's why I asked. The internal attenuator is designed for a 16ohm load and will present itself at approx 16ohm when nothing is plugged into the speaker outs. Replacing the 16ohm wire with the 8ohm wire will mean that the only "matched" combination will be when in full power and using an 8ohm speaker.
As soon as you engage the 0.1W attenuation you will be mismatching the output.
I mention this because people seem very worried about using the 8 ohm speaker with the 16ohm tap but one will be pretty much causing the same mismatch when exchanging the wires and using the attenuator.
It was probably me who said that 1W is such a low power that it doesn't matter but actually the same mismatch in a 100W amp doesn't matter either.

I read in an older post here that someone had installed a SPST switch on back and moved around some of the wirings as such to allow it to be switched from 16ohm to 8 ohm with the toggle. Have you seen that on here?

 

[santiall]

I read in an older post here that someone had installed a SPST switch on back and moved around some of the wirings as such to allow it to be switched from 16ohm to 8 ohm with the toggle. Have you seen that on here?

Hi, no, I haven't seen that but yes, you could install a switch. Still the mismatch will be there in one of the combinations.

 

[scozz]

Well yesterday I was playing my Dsl1hr through 2-16 ohm, 1-12 cabinets, using a daisy chain option one cab has. It sound much better, no surprise there of course, but one of the speaker cabs, the one on the receiving end of the daisy chain link, started breaking up intermittently.

I don’t know if the impedance thing is the cause, but the other cabinet seemed to be fine.

I immediately stopped playing and removed one of the cabs, and played a bit with just the one 16 ohm cab and no issues. It was late last night so I didn’t go any further but I’m going to try again today. Check all my connections, remove pedal board and go straight in.

I’ll report back, in case anyone is interested.

 

[Mike_LA]

In my stack I have 8 ohm celestions and wired the cab for series or parallel connections.

 

[Dogs of Doom]

Well yesterday I was playing my Dsl1hr through 2-16 ohm, 1-12 cabinets, using a daisy chain option one cab has. It sound much better, no surprise there of course, but one of the speaker cabs, the one on the receiving end of the daisy chain link, started breaking up intermittently.

I don’t know if the impedance thing is the cause, but the other cabinet seemed to be fine.

I immediately stopped playing and removed one of the cabs, and played a bit with just the one 16 ohm cab and no issues. It was late last night so I didn’t go any further but I’m going to try again today. Check all my connections, remove pedal board and go straight in.

I’ll report back, in case anyone is interested.

sounds like an issue w/ that particular speaker. Could be as simple as a dirty input jack, or loose connection. Could be the jack on the other cab has a bad connection.

definitely get it fixed

hopefully it's not the voice coil on speaker #2.

 

[vonjet]

Found this researching DSL1H to 8ohm

"with a SPST toggle switch to select 8 ohm and 16 ohm. 16 ohm orange wire going to PCB would go to switch and 8 ohm white wire would go to opposite side of switch. Switch center would then connect where the orange wire went on PCB. This way the attenuator circuit would work for both outputs. The original 16 ohm output jack would now become selectable for 8 or 16 ohms."

What do you all think? Would that make it selectable and keep the attenuator circuit working?

 

[fitz]

Found this researching DSL1H to 8ohm

"with a SPST toggle switch to select 8 ohm and 16 ohm. 16 ohm orange wire going to PCB would go to switch and 8 ohm white wire would go to opposite side of switch. Switch center would then connect where the orange wire went on PCB. This way the attenuator circuit would work for both outputs. The original 16 ohm output jack would now become selectable for 8 or 16 ohms."

What do you all think? Would that make it selectable and keep the attenuator circuit working?

Switch, wire swap, or second jack, the 0.1w attenuator mode will always show 16 ohm to the amp - this will never change.

 

[Dogs of Doom]

Found this researching DSL1H to 8ohm

"with a SPST toggle switch to select 8 ohm and 16 ohm. 16 ohm orange wire going to PCB would go to switch and 8 ohm white wire would go to opposite side of switch. Switch center would then connect where the orange wire went on PCB. This way the attenuator circuit would work for both outputs. The original 16 ohm output jack would now become selectable for 8 or 16 ohms."

What do you all think? Would that make it selectable and keep the attenuator circuit working?

it will work, but, as Santiago rightfully stated, the attenuator is matched to 16 ohm. If you run the 8 ohm tap into it, it will be mis-matched.

Read his post, a few posts up a few x's. No matter what you do, at some point, there will be a mis-match. You could add another attenuator (8 ohm) & make it so when you switch, the 8 ohm matches w/ the 8 ohm attenuator, etc.

But, if you simply switch taps, you will have a mis-match. Not much different than if you simply use the amp as-is w/ an 8 ohm load... It might be a little easier on the transformer & power tube, but it will be more work to add the 8 ohm attenuator.

 

[vonjet]

it will work, but, as Santiago rightfully stated, the attenuator is matched to 16 ohm. If you run the 8 ohm tap into it, it will be mis-matched.

Read his post, a few posts up a few x's. No matter what you do, at some point, there will be a mis-match. You could add another attenuator (8 ohm) & make it so when you switch, the 8 ohm matches w/ the 8 ohm attenuator, etc.

But, if you simply switch taps, you will have a mis-match. Not much different than if you simply use the amp as-is w/ an 8 ohm load... It might be a little easier on the transformer & power tube, but it will be more work to add the 8 ohm attenuator.

Understood. Thank You for all the help. I am just going to swap out the 16ohm Ten 30's for 2 8ohm G10 Vintage's

 

[fitz]

If you really want to come down the rabbit hole, the 16 ohm John H attenuator has an option for an added resistor on a switching jack that compensates for an 8 ohm load...

Simple Attenuators - Design And Testing

Background Passive attenuators are wired between the amp output and the speakers. Their function is to absorb most of the output power of the amp, feeding a smaller amount to the speaker itself. This allows the amp output stage to run at higher power, letting the glorious tone of a good valve...

www.marshallforum.com

 

[scozz]

sounds like an issue w/ that particular speaker. Could be as simple as a dirty input jack, or loose connection. Could be the jack on the other cab has a bad connection.

definitely get it fixed

hopefully it's not the voice coil on speaker #2.

Thanks, I didn’t even think about that, my brain went right to the mismatch. The thing is though it only happens with the Dsl1, my Bugera head and SC20h work fine.

I did notice the jack on the cab with the extra input, feels a little loose. I’m going to check that out and also spray a bit of DeOxit in the jacks and work it in.

I also have a Y speaker cable I bought from Weber quite a while back, but I’ve never used it for this. So I’ll guess I’ll give that a try, just because I guess,….

I don’t know st this point if anything will help, it looks like it’s the Dsl1 that’s the issue.

Thanks for the suggestions.

 

[Dogs of Doom]

Thanks, I didn’t even think about that, my brain went right to the mismatch. The thing is though it only happens with the Dsl1, my Bugera head and SC20h work fine.

I did notice the jack on the cab with the extra input, feels a little loose. I’m going to check that out and also spray a bit of DeOxit in the jacks and work it in.

I also have a Y speaker cable I bought from Weber quite a while back, but I’ve never used it for this. So I’ll guess I’ll give that a try, just because I guess,….

I don’t know st this point if anything will help, it looks like it’s the Dsl1 that’s the issue.

Thanks for the suggestions.

but, you say it's just the 1 speaker...

unless both speakers do it, when you have 2 hooked up. Try only hooking up cab #2 (the noisy one) on it's own. Does it work correctly then?

 

[vonjet]

If you really want to come down the rabbit hole, the 16 ohm John H attenuator has an option for an added resistor on a switching jack that compensates for an 8 ohm load...

Simple Attenuators - Design And Testing

Background Passive attenuators are wired between the amp output and the speakers. Their function is to absorb most of the output power of the amp, feeding a smaller amount to the speaker itself. This allows the amp output stage to run at higher power, letting the glorious tone of a good valve...

www.marshallforum.com

That would be cool to have but I would need some easy guided instructions on what to do. I can solder and have done all kinds of circuit board stuff but only because I have clear instructions on what to do. I'm not one to experiment with this stuff. Id ruin my amp.

 

[scozz]

but, you say it's just the 1 speaker...

unless both speakers do it, when you have 2 hooked up. Try only hooking up cab #2 (the noisy one) on it's own. Does it work correctly then?

Yes, just the one speaker cab, Creamback gm65, snd yes it does it when it’s the only cab used,….. but just with the Dsl!

That single Creamback cab sounds fine with my SC20 and my Bugera G5. I just finished playing all three heads through one cab each at a time, and together, for about 15 minutes. It only happens with the Dsl.

Kind of exasperating. Don’t know where to go with this at this point, I guess I might as well try the Y cable and see if that helps.

Thanks again for your help, it’s appreciated.

(Edit: sorry @vonjet if I hijacked your thread a little.)

 

[fitz]

That would be cool to have but I would need some easy guided instructions on what to do. I can solder and have done all kinds of circuit board stuff but only because I have clear instructions on what to do. I'm not one to experiment with this stuff. Id ruin my amp.

Probably not worth the effort.

As was discussed with above Santiago (if you're not aware, he used to be an amp designer for Marshall), running an 8 ohm load on the 16 ohm attenuator is just going to change the tone response from the speaker.
The resistor kinda compensates that difference to what the speaker might usually get from an 8 ohm signal.

Depending on the speaker, how you set the amp, what guitar you're using, any pedals out front or in the loop, and what tone you're going for, the tone difference from the mismatch may be something you like or not.
At the amp's full 1w output or the attenuated 0.1w, there's no risk to anything.

Time and expense involved in trying to make the DSL1 the best amp in the world might be better spent on just getting a better amp...
Possibly the main reason I never made any modifications to mine.
Sold it shortly after I got a 20HR.

 

[santiall]

I keep saying the same, you guys think too much : just plug the 8 ohm speaker and see how you like it. Nothing will break, nothing will blow up.

Swapping taps won't solve the possible mismatches and will create a new ones in certain conditions so there is no magic trick unless the circuit is modified with more switching and circuitry. That's why I designed it that way in the 50th anniversary version.

 

[Georgiatec]

From what @santiall posted it looks like you're good to go with your "Y" lead speaker cable.