Model guide

[mr_chrish]

Hi,

I was wondering if someone would like to make a quick guide to the different Dumble models, show the main differences, evolutions, pros/cons, if they're harder/easier to build etc.

As a newbie I've read about all these models and names, but I known little about what they mean. It's hard to sort all the information in this excellent forum, so I'm hoping this will help me and maybe others.

Thanks,
Christian

[Bob-I]

Even with all of my building, I'm not clear on all of the terms. I'll put down what I think I know.

Hybrid-A is a 70's model with 90's values. Great starting point for a new builder.

97 Skyliner is the later version using the "Skyliner" tone stack (can someone explain this?) and a Hot Rubber Monkey, HRM, post overdrive tone stack using trimmers.

[mr_chrish]

Seems like the Hybrid-A might be the place to start, as it's recommended by many. Normsters layout seems to be popular. Somebody wouldn't happen to have a parts list?

Thanks,
Christian

[Bob-I]

Seems like the Hybrid-A might be the place to start, as it's recommended by many. Normsters layout seems to be popular. Somebody wouldn't happen to have a parts list?

Thanks,
Christian

It's around somewhere, maybe in the files section?


Yes, Norms layouts are excellent.

[mr_chrish]

Found this: http://ampgarage.com/forum/viewtopic.php?t=892 but I can't see the picture. Is this the right one, and if so does anybody have a working url?

Looking forward to starting my first build, just need to stort some more details out and I'll be on my way.

Thanks,
Christian

[Luthierwnc]

The Hybrid A is a good place to start. It hasn't come up but is this your first homebrew? These are pretty complicated amps and even the basic recipes need some spices. A good first amp might be something like a Spitfire or 59 Bassman. Either way, pick a design and go with it. By the time you are done, you will understand the nuances better if you want to change some of the values. The interchangable parts are the cheapest components in the system so you can't make any big mistakes.

With one exception: If this is your first amp, study up on safety procedures. I've sent myself flying across the room more than once. Aiken, AX84 and Ampage all have short tutorials on how not to be a statistic.

Good luck,

Skip

[mr_chrish]

Thanks for the tips, always nice to hear what more experienced builders say.

Yes, this is my first amp, but I'm not new to electronics as I'm studying for a masters degree. I've build and soldered stuff many times before, but not as big and complex as a tube amp so I will try to take precautions. I've been electrified more than once, so I know all about that.

Thanks,
Christian

[Normster]

Found this: http://ampgarage.com/forum/viewtopic.php?t=892 but I can't see the picture. Is this the right one, and if so does anybody have a working url?

Looking forward to starting my first build, just need to stort some more details out and I'll be on my way.

Thanks,
Christian

OK, link is fixed. Bear in mind that this layout was specifically for converting a Bassman head to an ODS w/reverb, hence the push/pull switches on the pots. If you're building from scratch, Dumble's switch layout and wiring is far more elegant. Check Ben Shelton's excellent layout:
http://ampgarage.com/forum/download/file.php?id=597

Note that in this drawing, Ben used the odd OD input network as seen in pics of #40. He has since changed this to a 180k into 100k trimmer and likes it better.

For a better idea of control and relay wiring, you can take a peek at my 6V6 ODS layout:
http://bad-domain/6V6_ODS/6V6_ODS_full.JPG

The output and power sections are different, but most of the preamp is close enough to get you in the right direction.

I'm also working on documenting the layout for #124 based on Gil's post, but it's still pretty rough. May be a few weeks before I can actually finish it up. Here's a link in case you want to build something more traditional without reverb:
http://bad-domain/6V6_ODS/ODS%23124_layout.JPG

The component layout is pretty close to #124 except that I haven't changed the plate filters to those monster 330uF caps and haven't moved the B+4 filtering to a 10/10uF cap can as per Gil's pics.

Except for the Bassman layout, these drawings are based on a "standard" dimension Dumble chassis, i.e., 19" x 8" x 2.5".

Hope some of this rambling helps.

[mr_chrish]

This is excelent, thanks alot! You've just answered all of my questions and more.

Thanks,
Christian

[mat]

Whoa! Normster, really good looking layout You are an artist on the layouts

Have You already built the fet-input-unit ?

Three questions about the fet-board:

1) Am I right on these values and fet ?

[img:351:479]http://www.pichotel.com/pic/16028B31e/57806.jpg[/img]

2) What value is the trimmer ?

3) I would like to build it in to my clone (based on your bassman-layout), would it go as it is ?

I asked here for the NTE452 but no avail. I suppose any similar fet would go with this..

Thanks,

[Normster]

I haven't tried that one yet and already see mistakes. I'll make corrections to the original before someone else tries to implement. Here's a layout of the earlier style which I have used successfully. The trimmer is a 10k. Mouser usually has the NTE452s in stock.[/img]

[Normster]

and here's the corrected newer style FET...

[mat]

and here's the corrected newer style FET...

Big Thanks Normster for the layouts ! I will build it next (got the parts already, 2N4416 as the fet).

cheers,

['67_Plexi]

Nice job Norm !!

[blave]

I admire anyone who is willing to dive into building an Umble with no previous amp-building experience.

I am an electrical engineer, at least based on my degree, and I have soldered my way through several kits and projects over the last 30 or so years. However, I am still planning on starting with a *fairly* modest tube amp project before trying to tackle a Hybrid A or whatever:

http://www.backbeatbooks.com/?articleid=59

BTW the associated book is a MUST HAVE for ampophiles.

BTW #2 I really look forward to never getting tossed across the room by a misplaced finger or tool 8^) . I did manage to get a wake up call while prodding around an (unplugged) Fuchs-modded TBA-1 that I used to own, and that only made me go "hrrrrm" rather than become bodily misplaced, so I guess I got off easy that time .

cheers,

Dave Blevins