New 183 build

[Stephen1966]

Oh please, there is a TON of proof that standby switches 'can' be implemented and not harm an amp, but they are NEVER needed unless you're running tubes that operate well over 1000VDC. Tube Guitar Amplifiers never do.

This is science, fact, proven and hashed out over and over. If you MUST install a standby switch be very sure you implement it well so you don't damage the amp. It's just better to never use them. I haven't used one in an amp ever since I learned the facts about why standby switches were used and in what cases. Leo Fender didn't understand this so he put them on amps and now everyone invents reasons as to why they 'need' them that are just false history.

~Phil

Agree 100%. I'm building mine with them but as Bob said, there is one easy solution if you don't agree with them which is to always leave them switched on - just use the on/off switch. Cathode stripping, cathode poisoning - maybe it is all just supply and demand. I'm building this amp with the cheapest EL34s I could find. It isn't all about the tubes. On startup from cold it's always okay to throw both switches at the same time. The caps can handle the voltage spike and the tubes warm up and start conducting along with the filaments, I've always understood this to be safe from a cold start up.

[ijedouglas]

Oh please, there is a TON of proof that standby switches 'can' be implemented and not harm an amp, but they are NEVER needed unless you're running tubes that operate well over 1000VDC. Tube Guitar Amplifiers never do.

This is science, fact, proven and hashed out over and over. If you MUST install a standby switch be very sure you implement it well so you don't damage the amp. It's just better to never use them. I haven't used one in an amp ever since I learned the facts about why standby switches were used and in what cases. Leo Fender didn't understand this so he put them on amps and now everyone invents reasons as to why they 'need' them that are just false history.

~Phil

I don't have an opinion on this other than observing what HAD did. I think we can all agree he built some amazing amps and clearly understood certain things that few if any of us do. I'm curious why HAD would use a standby switch if you don't "need" it?

[WhopperPlate]

Oh please, there is a TON of proof that standby switches 'can' be implemented and not harm an amp, but they are NEVER needed unless you're running tubes that operate well over 1000VDC. Tube Guitar Amplifiers never do.

This is science, fact, proven and hashed out over and over. If you MUST install a standby switch be very sure you implement it well so you don't damage the amp. It's just better to never use them. I haven't used one in an amp ever since I learned the facts about why standby switches were used and in what cases. Leo Fender didn't understand this so he put them on amps and now everyone invents reasons as to why they 'need' them that are just false history.

~Phil

I'm curious why HAD would use a standby switch if you don't "need" it?

Dumble is heavily inspired by Fender. Cut and paste.

[Stephen1966]

Oh please, there is a TON of proof that standby switches 'can' be implemented and not harm an amp, but they are NEVER needed unless you're running tubes that operate well over 1000VDC. Tube Guitar Amplifiers never do.

This is science, fact, proven and hashed out over and over. If you MUST install a standby switch be very sure you implement it well so you don't damage the amp. It's just better to never use them. I haven't used one in an amp ever since I learned the facts about why standby switches were used and in what cases. Leo Fender didn't understand this so he put them on amps and now everyone invents reasons as to why they 'need' them that are just false history.

~Phil

I don't have an opinion on this other than observing what HAD did. I think we can all agree he built some amazing amps and clearly understood certain things that few if any of us do. I'm curious why HAD would use a standby switch if you don't "need" it?

I'm with you on that. I mean, there are several possibly plausible explanations for it. First, if he was just emulating Leo we have to ask ourselves if the only reason he would include it is because Leo did it! I don't buy that. And can we say that Leo was the first to come up with the fixed bias LTP? - MrD's section that most clearly resembles the Fender designs - I think, probably not, but I'm happy for you to correct me on that one. It feels a bit like trying to fit a round peg in a square hole with the idea that MrD copied anything, without knowing or fully understanding why. As you said yourself, Ian, it wasn't something he did just once, but again and again...

Let's suppose that he fully understood the role of the standby switch, that he knew its pros and cons. More to the point, that he knew the "harm" a standby switch could do. We ask ourselves the same question: why would he still include one? Was it possibly because this was something the players expected to see? It might not have been that difficult to find replacement tubes in those days, and "Hey! If you want it decked out in gold lamé, it's your dime!" But again... and again...?

Maybe there is another way of looking at this, which is to ask: Why, if he knew - as I'm sure he did - the harm it could do, why didn't he exclude it from his builds altogether? He was very clearly very protective of his reputation as a designer and builder and so, how did he understand the extent of how great the harm the switch could cause? We will probably never know the answer to that one, but it shouldn't stop us making an educated guess. Which is to say, if you use the amp sensibly and don't go leaving the amp in standby for long periods, and if the amp is left to cool down and fully discharge its caps between sets, the risk of harm, is probably very low... almost negligible.

Now, a project for any real Dumble owners out there... How many of you are still using the original tubes he installed? Forty years may be expecting a bit much from even the very best tubes, but if you have been looking after your amps, and playing regularly, how much life do you get from your tubes? That's the real test, I think.

[ijedouglas]

Dumble is heavily inspired by Fender. Cut and paste.

Perhaps. I guess that would also lump Ken Fisher, Jim Kelley and Randall Smith together in the same boat

[Charlie Wilson]

Yeah, to say a guy who was building PAs and designing amps for Mosrite when he was a teenager is cutting and pasting is a bit much.
CW

[pompeiisneaks]

Oh please, there is a TON of proof that standby switches 'can' be implemented and not harm an amp, but they are NEVER needed unless you're running tubes that operate well over 1000VDC. Tube Guitar Amplifiers never do.

This is science, fact, proven and hashed out over and over. If you MUST install a standby switch be very sure you implement it well so you don't damage the amp. It's just better to never use them. I haven't used one in an amp ever since I learned the facts about why standby switches were used and in what cases. Leo Fender didn't understand this so he put them on amps and now everyone invents reasons as to why they 'need' them that are just false history.

~Phil

I'm curious why HAD would use a standby switch if you don't "need" it?

Dumble is heavily inspired by Fender. Cut and paste.

Nail, meet head.... head, nail.

Edit: This came after I read more of the replies.

Why can't he just copy paste when he's using existing amps that already have them. Why change something if it's already there and NOT impactful. He knew his designs didn't have the side effect of the standby, so he just left them in. I too left mine in on my Fender Bassman 100 to Dumble conversion I did since it was already there. I built a bassman with a polarity switch. I left it in but not hooked up which is more possibly confusing for someone now that I think about it. If he knew his amps were going to add switches, change sliders, etc why didn't he just throw the chassis away and build it from scratch? Because it was simpler to use what was there, and leave what was, as is.. and only change what he 'needed' to. Are there any dumble amps built 100% from scratch? I'm not aware of any, but that's my limited experience.

Just because he's a genius, and an amazing amp builder doesn't mean a few other things can't be true:

1. he still surely can and did make mistakes
2. he surely did some shortcuts he was pretty confident had 0 impact on the tonal quality of the amp.
3. he also likely shrouded some of what he did in mystery and did some weird things that likely did NOTHING to tone just to confuse people... But I digress.

Either way, imo, unless you asked the builder WHY you're just guessing anyway and it's got about a 1% chance of being right

End Edit

~Phil

[ijedouglas]

Are there any dumble amps built 100% from scratch? I'm not aware of any, but that's my limited experience.

All Dumbleland/SSS/ODS/ODSR that I am aware of were built 100% from scratch.

[pompeiisneaks]

Are there any dumble amps built 100% from scratch? I'm not aware of any, but that's my limited experience.

All Dumbleland/SSS/ODS/ODSR that I am aware of were built 100% from scratch.

I've now seen multiple ODS that were built in a fender chassis, not from scratch no? He gutted them, and rebuilt, or did he actually get fender identical chassis' sent to him empty?

Maybe I've been mistaken but they always looked to me like a gutted chassis with existing transformers and everything else rebuilt... thus my statement it was rebuilt. to me 100% from scratch is buying an empty chassis, even if pre drilled etc, and building/buying an empty cabinet and buying/installing a speaker etc 100% is 'from scratch'. Reusing nothing. Copying nothing.

but I might be wrong. Again I've only seen some of the builds here, not all, only in photos, and by far that's a very small percentage of his amps.

~Phil

[ijedouglas]

Are there any dumble amps built 100% from scratch? I'm not aware of any, but that's my limited experience.

All Dumbleland/SSS/ODS/ODSR that I am aware of were built 100% from scratch.

I've now seen multiple ODS that were built in a fender chassis, not from scratch no? He gutted them, and rebuilt, or did he actually get fender identical chassis' sent to him empty?

Maybe I've been mistaken but they always looked to me like a gutted chassis with existing transformers and everything else rebuilt... thus my statement it was rebuilt. to me 100% from scratch is buying an empty chassis, even if pre drilled etc, and building/buying an empty cabinet and buying/installing a speaker etc 100% is 'from scratch'. Reusing nothing. Copying nothing.

but I might be wrong. Again I've only seen some of the builds here, not all, only in photos, and by far that's a very small percentage of his amps.

~Phil

None that I know of. I think the Overdrive Deluxe (owned by Keith Urban) was a re-used Fender chassis. I know some of the other models (Ultraphonix/Rockphonix/HoteHog/La Tostada/Purple Haze/Tweedle-Dee) were built in stripped down Fender or Marshal chassis but the models I mentioned were all custom built.

Please send a link if you have an ODS in a Fender chassis, I'd be interested to take a look?

[Stephen1966]

Enjoying the conversation very much.

An interlude... I think I've figured out the topology of the 183 power board.

183 PS topology.jpg

For a while, I couldn't figure out what the red wire with a blue stripe was leading to, but I think it is going under the board and connecting up with the left leg of the 3k dropping resistor as viewed in the photo. Odd, because there looks to be plenty of room for that to be made into a trace on the board, but maybe he was laying down heavy traces - in order to handle the current better - it's the only explanation I can come up with. I seriously doubt it would be because of sloppy work!

Red - blue stripe.jpg

And this shot, with the merest hint of red lead on the uppermost leg of the 3k resistor.

Red - blue stripe from side.jpg

The reservoir caps appear to have a dedicated GND and I'm surmising it goes off to GND 4 in the bottom left of the chassis but it's interesting that everything from the screen/grids (B+2) all the way down to V1 (B+5) share a single common ground - I can't see any other eyelets for ground in the photos. It seems unorthodox, assuming the ground wire goes off to GND 1 near the input jack. I would be concerned about the difference in ground potential, but what do you think?

[bepone]

now, all those gnd's.. is wrong to connect in one point..every gnd electrolyt wire must go to belonging cathode/ or cathodes.. like old Fender amps have..

per example node no2, gnd, must go to the cathode of output tubes, if they are on the chassis, this gnd wire must go also there..

[ijedouglas]

For a while, I couldn't figure out what the red wire with a blue stripe was leading to, but I think it is going under the board and connecting up with the left leg of the 3k dropping resistor as viewed in the photo. Odd, because there looks to be plenty of room for that to be made into a trace on the board, but maybe he was laying down heavy traces - in order to handle the current better - it's the only explanation I can come up with. I seriously doubt it would be because of sloppy work!

I believe the red wire with blue stripe is the return from the standby switch. The black is from the OT and purple goes to the screens.

[Charlie Wilson]

Are there any dumble amps built 100% from scratch? I'm not aware of any, but that's my limited experience.

All Dumbleland/SSS/ODS/ODSR that I am aware of were built 100% from scratch.

I've now seen multiple ODS that were built in a fender chassis, not from scratch no? He gutted them, and rebuilt, or did he actually get fender identical chassis' sent to him empty?

Maybe I've been mistaken but they always looked to me like a gutted chassis with existing transformers and everything else rebuilt... thus my statement it was rebuilt. to me 100% from scratch is buying an empty chassis, even if pre drilled etc, and building/buying an empty cabinet and buying/installing a speaker etc 100% is 'from scratch'. Reusing nothing. Copying nothing.

but I might be wrong. Again I've only seen some of the builds here, not all, only in photos, and by far that's a very small percentage of his amps.

~Phil

Really, please direct me to just one. I know Dumble was rather insistent that he do everything. He screened and painted his chassis, built his own head shells and speaker cabinets and so on. The ultraphonix were the only amps I know of that he used the original Fender chassis.
chassis.
CW
Can you "Dumble-ize" a Fender amp to the point that it shares the Dumble philosophy and sound, or would it be a compromise?

It's a compromise. The actual physical construction of the Fender limits what can be done. In fact, after the last Steel-String Singer mod I did to David Lindley's amps, he no longer uses the Fender Bassman I Dumbleized for him. He wanted this luscious transparency and response--like floating in white clouds--and I came up with special circuitry. I can use a Fender chassis, but you have to rip everything off of it, fill in all the holes, and re-drill it. They're just a little bit too squashed. A distance of half a centimeter makes a big difference in the way something sounds. It's a science involved with what's called circuit constants.

[Stephen1966]

I believe the red wire with blue stripe is the return from the standby switch. The black is from the OT and purple goes to the screens.

Hmm! I thought that too for a while... if the BLK is the CT (B+) for the OT though, it would sharing the node with VIO (or purple) with the screens (B+2); B+ and B+2 together? I can't quite get my head around that. There does indeed, seem to be another Red/blue stripe wire hanging around the back panel of the chassis near the switches, but that looks like it connects up with the ground switch.

Ground switch.jpg

is wrong to connect in one point..every gnd electrolyt wire must go to belonging cathode/ or cathodes..

Agree! I think this is where Tony's layout is the more reliable as well. I see now it is possible with the 183 board as well:

183 PS topology(2).jpg

I think just by separating the grounds between C29 and C31 we can isolate the screen's node (B+2) ground from the PI (B+3), OD (B+4) and CL (B+5). And, if we take the B+2 ground and attach it along with the B+ ground, it explains why he would need to pass a separate lead under the board from the B+2 node to the 3k resistor on the other side: the path is effectively blocked by the extra ground trace. It makes sense. It's not because of any lack of space for extra traces. I can't see any other ground connections in the photos, maybe there is one tucked out of sight somewhere, but this all seems to fit. And, if the first ground connection on the left goes to GND 4 (considering the 124 documentation) it could be that the second, on the right, either goes to GND 2 or GND 1. We might also connect the grounds for the reservoir caps (B+), screens (B+2) and PI (B+3) this way as well - isolating the preamp grounds from the higher energy sections.

Just hoping to understand his topology here before I design my own PS but if you are hoping to recreate his design this might be helpful as well. As I understand it, when Shad deconstructed the 183 to clone it, he changed the PS layout and cap orientation as well. I actually only see one ground coming off his board but there's only so much you can gather from bits of information here and there. Tony's layout looks good to me.