Newbie needs help - Bandmaster Reverb to Dumble project

[johan]

Hi there,

This is my first post and I have to thank Omar for a wonderful place and some of you guys for directing me to this site.
I’m in Sweden and have been a lover of Dumble amps since the first time I saw Robben at the time of the first Blue Line album. Magic!

Went through a lot of amps but found a 66 BF Super Reverb I loved. Since it’s such a piece of history I don’t want to ruin it with modifications.
Some time ago I bought a Vibroclone (64 Vibroverb w 15”) a friend of mine built from a 70’s Bandmaster Reverb head.
Since then it’s been modded for a more brown Fender type of tone, nothing for me. Got the idea of making it more Dumble like.
Since the amp is no holy grail I can do pretty much what I want with it…

Take a look at it here. http://web.telia.com/~u04201604/fender.htm
The amp now has 2x10” speakers. I’ll probably install a 12” G12-65 or similar speaker.
I have two different Kendrick transformers, 4 or 8 ohm both for 6L6 tubes, to choose from.

First – I have no or very little electrical knowledge. A friend of mine will do all the work so keep that in mind.
He’s done some Dumble mods for his BF Fender – the ones on schematic heaven – so he know what he’s doing but after reading here for an hour I understand there’s so many different versions.
What schematic do you recommend? Maybe a full schematic with some “add-on” schematics for certain things like reverb etc.

The tone I’m looking for is the Handful of Blues/Mystic Mile albums by Robben Ford.
I think his lead tone has got a bit buzzier the last couple of years. I don’t want it too be too smooth like some people like it – a bit too slick for me.
Listen to HOB and the tone has a bite to it. Clean tone – what I’m using 75% of the time anyway, is full, warm with a nice bloom to it.

What do you recommend for this amp?
Is it a good starting point for a project like this?
I can live without the tremolo in the amp and use the pots/space for Master + Presence?
Is the “lead-channel” a lot of work or should I keep it a clean Dumble ODS amp with boost/deep/rock/jazz etc and use a Zendrive for lead?
If I go for the Overdrive section with content / ratio maybe I can put the on the rear? Somebody must have done a BF Fender mod like this before?! HAD use old Bandmaster heads for his mods. (Landau or Henderson comes to mind)

I’ll stop here and add more later when I've got some guidelines from you.

Thanks a lot for this wonderful place. What a gold mine!

Regards

Johan

[johan]

I'm sure some of you can give me some guide-lines

Thanks alot in advance!

[groovtubin]

I'm sure some of you can give me some guide-lines

Thanks alot in advance!

run a skyliner pream/eq into a twin output section, and enjoy....play LOUD...

[Pete]

One approach would be to start with the chassis with transformers on it, then add the basic overdrive special circuit built on the bandmaster circuit board. Filtering can stay under the bottom cover like most Fenders.

If it was mine I would have no tube rectifier and no reverb, easier to build and sounds better, IMHO. Also I would leave out Bright, Deep & Jazz/Rock (never used by R.F.)
Use the biggest, most appropriate output transformer you have (original bandmaster is not as good as Super Revb or Bassman type)
Footswitching could be added, adding a small transformer or using 5v tap.

[johan]

What type of OT do you recommend for this amp?

Kendrick 2410A-8
Mercury Magnetics for Twin etc
Mercury Magnetics OD-50 (Dynaco 50)
Mercury Magnetics FBFVL-O (used for BF Vibrolux Reverb etc)

Is the components crucial to the tone? Silver Micas / Ceramic etc etc...

Which version should I go for?
groovtubin said "skyliner pream/eq into a twin output section"
Pete: "No tube rectifier and no reverb"
There so many version out there and I want to be sure I pick the right one. Can I get some more opinions? Anything suitable for a two 6L6 amp like this. Robben Ford 90's type of tone.

Is it difficult to keep the wonderful BF Reverb in a ODS amp?

Appreciate your help

[heisthl]

I have a different opinion on having tank reverb on these builds. If you have the space for 2 tubes use a slightly modified Prosonic reverb cuircut with a short style 3 spring medium delay tank. IMHO this combination sounds better than the either the Black or Silver face design and has the same impact on tone as having no reverb with a 220K/270K divider between the pre-out and pwr-amp-in jacks. You can power both tubes from the B+3 node with a slight adjustment of the dropping string. See the schematic in the files section
https://tubeamparchive.com/viewtopic.ph ... highlight=

[heisthl]

Ooops there was an error showing a 10K instead of a 100K across the tank output on that schematic - look at this one for reverb instead:
https://tubeamparchive.com/viewtopic.ph ... highlight=

Also bear in mind this reverb flips the signal phase so you need to reverse the reverb transformer return leads to make it phase neutral.

[Bob-I]

What type of OT do you recommend for this amp?

Kendrick 2410A-8
Mercury Magnetics for Twin etc
Mercury Magnetics OD-50 (Dynaco 50)
Mercury Magnetics FBFVL-O (used for BF Vibrolux Reverb etc)

I don't know about the Kendrix, but I've used MM's before and they sound great. Personally I'd start with what you have and swap it out only if it sounds really poor.

Is the components crucial to the tone? Silver Micas / Ceramic etc etc...

There's been tons of discussion around this. Before I type a ton, try doing a search for caps and resistors. If you strike out I'll jump in and help.

NO Silver Mica's!!

Which version should I go for?
groovtubin said "skyliner pream/eq into a twin output section"
Pete: "No tube rectifier and no reverb"
There so many version out there and I want to be sure I pick the right one. Can I get some more opinions? Anything suitable for a two 6L6 amp like this. Robben Ford 90's type of tone.

Robben has changed his tone so much over the years it's hard to say.

Is it difficult to keep the wonderful BF Reverb in a ODS amp?

Appreciate your help

Yes, but the Glaswerks single tube reverb or the ECL86 reverb are both excellent. I prefer the ECL86 reverb (cauz I designed it) . Boht are posted on the files forum.

[Bob-I]

I just looked at your clone, looks great.

If your goal is more aggressive, not soft and sweet, I'd recomend a 70's Dumble ckt. Normster did one using 70's values and layout and it sounded punchy and gutsy. Check the files section.

Also, I took a Super Reverb clone and by using the normal channel's tube built an ODS ckt. It took minimul mods and all are reversable. I'm currently drawing up a layout which I'll post when I'm done.

[johan]

Hi Bob-I
Thanks alot for your replies. Very good information for me.
Maybe I should start slow and go from there. Will not do the work myself but maybe the Normal channel is a good start and keep the Vibrato channel stock (64 Vibroverb).

What can one do with a Normal channel on a BF Fender? "Dumble clean" or just a "twist" of the BF Fender tone?
It's got Vol-Trebl-Bass + the bright switch only. Don't I need a middle control and some space for switchers?

Groovtubin said "skyliner pream/eq into a twin output section". Can this be done on the normal channel? The Skyliner preamp/eq that is. output section will remail 64 Vibroverb I guess.

Thanks alot for a wonderful forum!

[Bob-I]

Hi Bob-I
Thanks alot for your replies. Very good information for me.
Maybe I should start slow and go from there. Will not do the work myself but maybe the Normal channel is a good start and keep the Vibrato channel stock (64 Vibroverb).

My mods have many changes to the vibrato channel as well. If you keep it stock you won't nail the Dumble vibe.

What can one do with a Normal channel on a BF Fender? "Dumble clean" or just a "twist" of the BF Fender tone?
It's got Vol-Trebl-Bass + the bright switch only. Don't I need a middle control and some space for switchers?

Yes, you'll need a mid control. Without drilling on the chassis, you might need to use the second input as one ot the controls. Typically folks replace the faceplate when they do a transplant.

Making the Dumble clean only can be awesome. I really like the tone of my little 6V6 Dumble clean channel when you hit about 6-7 on the master volume.

Groovtubin said "skyliner pream/eq into a twin output section". Can this be done on the normal channel? The Skyliner preamp/eq that is. output section will remail 64 Vibroverb I guess.

Again, you might need to do some mods to these sections if you want to nail the true Dumble charactor, but you can do some minor changes and really make the amp nice.

Check out some of the Dumble mods on schematicheaven.com . The changes to the tone stack make a big difference, you might like to start there.