Dumble Lite? - Update, Finished!!!

[Normster]

I've been toying with the idea of building a stripped down version of a Dumble ODS that's cheap and easy to build. My objective would be to put together something that a beginner could build without going into debt or getting in over their heads. I know Bob has been able to build some great sounding amps for under $300.

Off the top of my head I'm thinking 17x8x3 Bud chassis ($28 ), Hammond 272DX PT ($47), Hammond 1650F ($53), 6V6, SS rectifier, no choke (10W/500 Ohm resistor), Xicon MPP caps, Nichicon electrolytics, etc. If we use switches instead of relays, it will keep things simpler as well. (It should be layed out so that relays can be added later once the beginner has gotten to that stage of amp building.)

Anyone interested in doing something like this as a "community" amp project?

[oldmacman]

I'd say go with 6L6's and use Weber Bassman iron. Makes it loud enough to gig, and for not much more money.

Do an '80s without the PAB and use the Weber kit for the relay switching. No pops or clicks, and no additional transformer required.

I've used the Nichicon filter caps in several of them and they work great and they're cheap. If you can figure out some way to use radial caps, it's even cheaper.

You really don't need a 3" tall chassis. 2" would be fine if it's available. Be sure it's aluminum though. Easier to drill and sounds better.

[Normster]

I'd say go with 6L6's and use Weber Bassman iron. Makes it loud enough to gig, and for not much more money.

Do an '80s without the PAB and use the Weber kit for the relay switching. No pops or clicks, and no additional transformer required.

I've used the Nichicon filter caps in several of them and they work great and they're cheap. If you can figure out some way to use radial caps, it's even cheaper.

You really don't need a 3" tall chassis. 2" would be fine if it's available. Be sure it's aluminum though. Easier to drill and sounds better.

I'd prefer a 2" chassis as well, but the only thing I could find "commonly available" is a 3". 6L6's with Weber iron would be a good alternative for those who need the extra headroom. (Although the 6V6's will get pretty loud as well.) As for the radial caps, that's a good idea. They can easily be mounted with the leads through the board and bent over to an eyelet.

The only reason I shied away from relays is because of all the trouble they seem to give first timers. To be honest, I hardly ever play the clean channel anyway. I just set the amp up for nice breakup and then back off the guitar volume when I want clean tone.

[Ed de Jager]

Hi, ithink it is a good idea.
I just ordered a chassis at ampmaker in the UK.
Maybe the amp can be build into sections?
First the poweramp and od and if that is working well the clean channel and the relays.
I built an amp with channel switching relays already but had horrible popping problems in the beginning it worked o.k. but it costed a lot of headackes.
Things like mounting the diode directly onto the relay would be a handy thing to know for the ampbuilder.

Ed

[rfgordon]

Sounds like a cool project. If I were using radial caps I'd mount tag strips on a piece of garolyte and use the tags for the leads and silicon-glue the caps to the board.

As for chassis, I just built an amp for a guy using LMB Heeger chassis. (www.lmbheeger.com) They have most of the common sizes and free shipping.

[Bob-I]

I've been talking to Allyn about a small parts kit. He's digging through the stock that he recently bought, the 5 truckloads of parts. www.ampbuildersparts.com He's giving decent deals to us too.

I'm not a fan of Hammond OT's, I find them a bit sterile sounding but the Weber seems pretty good. I have one of the 40 watt OT's W404248 in my Super Reverb. 4K primary and 2-4-8 secondary. Should fit the bill well and only costs $38. The Hammond PT should be fine.

Another choice Normster is to take a Weber kit like the 6A14HP and make a new fiber board, throw out the small parts and build in that. The 6A14HP is a beefed up Princeton reverb, bigger OT and 6L6's instead of 6V6's.

Take a look here. https://taweber.powweb.com/store/kits.htm . He supplys everything for $500. Another $100 for the caps pots and resistors and you'll have a Dumble combo. For $440 you can get a head kit. It comes with a beautiful chrome Fender BF style chassis, ceramic tube sockets, weber iron, weber speaker, a well made cabinet, fiber boards caps resistors etc. His resistors are chinese carbon films and caps are chinese poly or mica.

You could go to a larger chassis in the 6A20HP which is a Deluxe Reverb clone for only $15 more.

Check out the whole site, lots of choices of chassis and cabinets.

[Bob-I]

I almost forgot. Those prices include a reverb pan, reverb xformer, choke and an ok set of filters.

[Luthierwnc]

Remember, no good deed goes unpunished.

I'd go with a 6L6 platform too. Modern 6V6's can handle the volts. As long as the bias has a wide enough range, people can downsize if they want. You'll need a multi-tap OT. Base it on a Hybrid A and leave enough room on the board for relays if builders choose the sport package.

One rant I have had for a while is why can't the cannister cap makers put separate grounds on the dual models. If the 2X100 and 2X50 units could be run in series, it would let us build vertical and save some room. Mention it.

Be sure to write a serious disclaimer that injured parties have no recourse to your personal assets -- maybe even one they have to sign-off on; like upgrading your iTunes software. FWIW, Skip

[rfgordon]

I second that emotion on the caps! Separate grounds would make the 100/100 LOTS more useful. I've got some 600VDC caps and they're just soooooo long it's ridiculous.

[Normster]

Many cool ideas!

Bob, I only mentioned the 6V6 build because the trannys were cheaper. If the Weber iron works out it's a wash anyway. BTW, I did check the price of Deluxe (25 watt) iron on Weber's site. Only $40 for the PT and $20 for the OPT! The kits are pretty reasonable as well but I think we can do a scratch build for under $300. Of course, that means a lot of chassis work so it's nice to have a pre-punched chassis as an option.

Man, I third the cap can thing! It would be cool to use a series 2/100 for the plates and a 40/20/20/20 for the screens and preamp. Maybe have Bob at Eurotubes talk to JJ for us. (He does have a nice JJ 50/50uf 560WVDC in stock though.)

As for the disclaimer, this IS an amp builder's forum but it wouldn't hurt to remind a beginner that "lethal voltage" means death on contact.

[Luthierwnc]

You might also check with Doug Hoffman about boards. He is already in the garolite business and does some pre-fab work on other popular models.

Mojotone's wholesaler prices are also very good and they use mostly Heyboer iron. They are within a couple bucks of the Weber (which I have also used and liked). I like the JTM45 OT in particular because it has 0-2-4-8-16 ohm leads so you can use it for a wide range of outputs. Hefty units. One thing Mojo can't do is technical advice. You either know what you want or not. Same with Steve Melkisethian. Email me on the Mojo prices if you don't have an account with them.

One thing that has helped me out over the years is doing an Excel spreadsheet for parts. If I have a couple amps going, I run columns for; part, part number, quantity, vendor, price and then which build it is for. No matter what sequence you enter items, you can resort by vendor, cut and paste and have your BOM. It works especially well for Mouser since you can download it directly to their order sheet.

sh

[Icetech]

After the crap weber did over at 18watt.com i won't give him another penny ever... and urge others in the same way... But thats just my $.02..

Btw... sounds like a cool idea norm:)

[MarkB]

I just got a Bassman OT and a choke for a 4x6V6GT build - and I'll be happy to buy from Ted in the future - great guy, thousands of happy customers.

Just my .02.

[rfgordon]

Regarding having boards made, I've talked to Ken at Turretboards.com about that very thing. He'd charge a one-time design fee of around $20, then price the board by its size. He's been super flexible with me, making Matchless Lightning boards for me with altered cap spacings and such.

[Icetech]

Mark, i had nothing but great service from him in the past... BUT after the crap with lawyers and shit.. and messing with a board that supported his end users and products.. It is just my personal choice not to give him my money, and i hope that anyone that was around 18watt at the time will do the same:)

Plenty of places to buy... no need to support those that don't support the hobby or do things to hurt it...