New user intro, and where to start??

[Mickey_C]

Hi All,

Glad to have finally found Amp Garage and the Dumble forum!

Name's Mike Corrieri, but I go around the web pretty much everywhere as Mickey C. I build amps, there's info on my site at http://www.soultoneamps.com , but I'm a total newbie on dumbles.

And I'm dying to build one!

Onward:

I have some parts I am hoping I can use for this project:

1) Chassis with 4 novals, 3 octals, cutout for a Triad 8087 PT.

2) Custom wound mercury Triad 8087 with flying leads, 350-0-350, and a whopping mother of 7amps 6.3, and a 5V rectifier tap too. Actually I have a stack of these, as I was using them for a design, but ended up changing to a different PT. So if these will work, it'd be a saving grace.

Where should I start? I was considering the Bassman layout, as it's not terribly far-off from the hardware I mention above.

Also, should I use a bassman OT with that? I have tons of marshall iron, so I'm curious if any of that is acceptaple.

[Icetech]

If you have a bassman OT, i would use it... since i believe thats what the real ones used:)

Im sure marshall would work though.. nice thing bout building your own is you get to try other parts and come up with your own flavor:) no such thing as a true clone anyway...

[Normster]

Hi Mike! Welcome to the dark side...literally. (Dumbles aren't nearly as bright and cutting as the 18watt.) BTW, gorgeous builds on your site!!!

Unless you're converting a Bassman, there are much better layouts than the BM posted here. The chassis sounds like it has everything you need and the PT is plenty beefy. The Marshall OPT will probably be fine as well. That's what Glaswerks is using and his amps sound amazing. (Dogears says they're even better running KT77's.)

[Bob-I]

Those PT's sound like great. You won't need a tube rectifier so you could use the 5V tap for relay power. With the 4 novals you could have reverb too. I'm building one using an ECL86 for reverb (I posted the reverb schem on the files page).

I like both the Hybrid and HRM amps myself, but I'm not a fan of the 70's style with Fender Rp and Rk/Ck values. I'd start with one of Norm's layouts, the 6V6 amp is excellent, I base my layouts on that one.

Component selection is important on these amps. Rp should be a quality metal film, Vishay Dale RN65's seem to be the gold standard. Coupling, tone and bypass caps are critical as well. I like the Xicon MPP series for uF values and many folks use the Orange drop PS series. I'd stay away from Orange drop 715's and Mallory 150's, they just don't give you that smooth Dumble tone. On the pF value caps stick with cheepy ceramics. I tried silver mica but I felt like there was a veil over the speakers.

Good luck, stick around here, lots of smart folks here that know these amps.

[Luthierwnc]

Welcome aboard! Very nice amps on your site.

Those trannies should work fine. There are two abiding philosophies I recommend, in addition to all the technical stuff: one is that you don't want a lot of saturation in the power section. The preamp in this build does most of the work. High volts (relative the power tube range), plenty of iron and biased for headroom. The second is that you should stay away from retro-components. Vintage spec-ed parts that add mojo to classic circuits get muddy when this gain structure is cascaded through them. Conversely; cold, modern components that can make 50-60's amps too sterile give the clarity you need. Bob-I mentioned some above.

Give yourself a little extra room. Most of the 50-watt chassis' you see here are deeper than a Marshall and taller than a Fender. The Bassman works but isn't ideal.

Make a Reverb-o-loop to go with it!

I'll look forward to seeing how you do.

Skip

[Mickey_C]

Good news, all the way around.

I've got a 50 plexi Mercury OT that I was hoping to use - sounds like I can do that!

I was thinking of the bassman layout, being the control layout was already punched. Cheesy as it will be on a dumble, I'll need to put a plexi panel on the front. But I will construct a very Non-Marshall looking head for it.

Any pointers to the schematic to aim for, and recommended BOM, would be appreciated.

Also, are the relays noisy? Would it be smarter to aim for bjFET shunts instead? Anybody worked out the transistorized switcher yet?

Thanks to everybody for the warm-welcome - and I'm looking forward to the fun!

Mickey

[Bob-I]

Any pointers to the schematic to aim for, and recommended BOM, would be appreciated.

The Hybrid-A is a great place to start, so is the HRM. They're both posted as ODS101 on the files page.

Also, are the relays noisy? Would it be smarter to aim for bjFET shunts instead? Anybody worked out the transistorized switcher yet?

Nope, quiet and fast. I haven't seen any other method of switching.

[Luthierwnc]

Here are a few more items for your think list (all my humble opinion):

HRM amps seem to favor British-flavored speakers while the Hybrids like big-magnet, high-wattage speakers. HRM's also prefer buckers. You can use a Tele too but I can't get a good sound out of a Strat. If you are a Strat guy, try the Hybrid first.

In your case, I doubt it will matter. My guess is you'll have three of these cranked out before you make up your mind which you like. My ability to stop at just one is a spec in the rearview mirror

Cheers, Skip

[Bob-I]

HRM amps seem to favor British-flavored speakers while the Hybrids like big-magnet, high-wattage speakers.

That hasen't been my experience. I've never found the Brittish types, Celestion Greenbacks or 1230's, to sound great on any of my Dumbles where the high wattage speakers like the Eminence RW&B's and EVM's sound great.

HRM's also prefer buckers. You can use a Tele too but I can't get a good sound out of a Strat. If you are a Strat guy, try the Hybrid first.

Good point and exactly my experience. Since I'm more of a bucker type I prefer the HRM amps but my Hybrids sound great with the Strats, even my cheepy TacoCasters.

[Normster]

The HRM circuit can sound pretty good with a Strat if you go to a .05uF mid cap. It's a little dark sounding with humbuckers, but not woofy. I think Scott recommended a .02uF as a good compromise, but that may have been on the Hybrid-A only.

[hipbluescat]

Hello All

I am also a first time user of this forum.

I have also built a number of amps. These are:-
1. Fender Deluxe reverb
2. Fender Bassman
3. Fender Tweed Super

Currently I am finishing a Fender Super Reverb.

But I do have the itch to build a Dumble Overdrive amp that would produce Robben Ford / Larry Carlton style tone. I need some assistance
before I can confidently start this project !

Which circuit on this forum would suit do this job ?

I am thinking of getting a chassis from a guy in Thailand. He as a thread on this forum. https://tubeamparchive.com/viewtopic.ph ... ht=chassis
http://vasinguitaramp.tripod.com/id4.html
Has anyone used this guy chassis before ?

Concerning transformers can anyone point me in the right direction. Which model would suit the overdrive amp. I am building from scratch.

My understanding is that these are the main types of circuits
1. Hybrid A
2. HRM
3. Non HRM
4. Bassman
5. 70/80's Overdrive Special

Is this correct ? What have a missed? What is the main differences between these circuits.

All input would greatly appreciated. Thankyou in advance.

Regards

[brownnote]

Hey Mickey!
Good to see you over here, I think you're gonna like it.

[Bob-I]

But I do have the itch to build a Dumble Overdrive amp that would produce Robben Ford / Larry Carlton style tone. I need some assistance before I can confidently start this project !

Cool. Keep in mind that these 2 use their Dumbles quite differently. Robben uses several settings, clean, clean with PAB (Preamp Boost), OD, OD with PAB and through a 2x12 or 4x12, where Larry uses just the clean channel cranked to the edge of distortion, then mikes his 1x12 through his own on stage PA.

Concerning transformers can anyone point me in the right direction. Which model would suit the overdrive amp. I am building from scratch.

Again, it depends. I'm a fan of 2x6L6 output so the best IMHO is Fender Bassman replacements. I've used several including the replacements from New Sensor and Antique Electronics. If you want to go with 4x6L6 use Twin Reverb type replacements and if you like EL-34's use Marshall type replacements. JMO.

My understanding is that these are the main types of circuits
1. Hybrid A
2. HRM
3. Non HRM
4. Bassman
5. 70/80's Overdrive Special

Close...

1. Hybrid A is a 70's ckt with 90's values. I like this one a lot, very aggressive and lots of punch.
2. HRM is the 90's ckt. More singing and sweet than the Hybrid. I like this one a lot too, most likely my favorite of the Dumble ckts.
3. Non-HRM is the same as the Hybrid and the 70's style.
4. Not really a Dumble. Lots of folks have transplanted Dumbles into the Bassman chassis though.
5. 70's/80's ODS are Dumble ckts with Fender values. I'm not a huge fan. I find them to be to gritty for me. They sound more like an overdriven Fender than a real Dumble.

IMHO the real key to the Dumble tone is the grainy smooth overdrive, not a lot of gain but plenty of singing sustain, plus the fat warm clean channel.

Enjoy the addiction. I have 6 Dumble like amps now, gotta start selling

[hipbluescat]

Bob

Thanks for the reply. Can you tell me about the 6 amps that you have made.

Sorry but I do not understand some of the terminology that is been used.

What does "CKT" stand for?

What does 90 's values mean ?

Would you use resistors that are metal film and have at least 1 watt in value ?

With the coupling capacitors would you use at least 600 volt rating like sprague 716 series ?

For the Robben Ford sound would the hybrid A circuit be a good base to start with ?

Regards

[Darkbluemurder]

Sorry but I do not understand some of the terminology that is been used.

What does "CKT" stand for?

It's the short form for "circuit".