A DIY Dumble Clone Demo: DLT Amplification Pumble

[dr.barlo]

Hi guys,

Here is an DIY amp that a friend of mine recently has finished. It is basically a Dumble clone with some twists. I think it turned out to be a great amp...

http://www.youtube.com/watch?v=bklvTPN1hfA

The PT and OT are Hammonds, and PT is one for a 50W Marshall Plexi. (Hence, "Pumble"... ) He used KT77 tubes, and 12AX7's. But I liked the amp with 5751's in v1 and v2 and 12AT7 in V3.

In this part of the world (Istanbul) finding a Dumble for a real comparison is kinda difficult. I had tried one in Willies' Guitar Shop when I was living in Twin Cities (in fact, my place was quite close to that store on Cleveland Ave.) way back when (like 2002 or something...). Anyways I wanted to share a recording (I have done in a practice studio with this amp and my strat, at high volumes) and get your feedback. The details are in the video... And please notice that I am not into this Dumble frenzy... I think it is a great sounding amp with a Blackface clean channel and big yet clean sounding overdrive channel.

Hope you like the demo

Appreciate your feedback about the tone of this amp.

Best,

B

 

[Fresh_Start]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

I wish there was more of the "overdrive" channel on the demo. It sounded nice. Not quite as much of the singing bloom you hear with some Dumble clones though. Can't tell how touch responsive it is.

The "clean" channel sounded cool with the Master turned up, but not "Blackface Fender" to my ears. I like it, but the classic BF top end sparkle wasn't there and it sounded a bit dirtier. Could just be the tone control settings or guitar, recording setup, etc.

I've never seen, let alone played, a Dumble and never will get the chance. So please take my comments for what they're worth - I'm an amateur amp builder and lousy guitarist.

Cheers,

Chip

 

[dr.barlo]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

Thanks for the feedback Chip. Appreciate it.

Regarding the sparkle on the clean side of the amp (with respect to the Blackface Fenders)... I guess that's a bit my fault. I am a Plexi guy at heart, and cannot take much treble. So I never ever used the bright setting in this demo for this amp. Still that might not be the only reason. But I guess it might apply, especially because I have a tendency (if you want, sorta curse) to make different amps and guitars somehow sound (with eq stuff, and the tone knob on the guitar) to what I like and what I wanna hear in my head... Which is generally a tone tending to that of a Marshall Plexi...

Yet, an important thing of this amp is that the OT is that of a Plexi... Maybe that's the reason...

Best,

B

 

[DankStar]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

it's got DLT in the name, hehe.

 

[That90'sGuy]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

I like it

 

[dr.barlo]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

Thanks man...

BTW what's up with the DLT? I dunno...



B

 

[STRATDELUXER97]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

Nice playing overall Doc...I liked the sound of the amp also...Good recording and it really did give a nice example of how the amp sounds..Sounds like a keeper to me.

 

[dr.barlo]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

Thanks John, glad to hear these.

:thanks:

B

 

[stevie_bees]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

It's the sort of amp that encourages you to want to play more, and that has to be a good thing!! The recording comes across well on YouTube, which makes a nice change.
Congrats on your build, and if I endorse the amp, how soon can you have it shipped to me!

 

[dr.barlo]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

Thanks Stevie, appreciate the comments.



B :beerchug:

 

[STRATDELUXER97]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

I think Doc said it was his friend's amp?

 

[dr.barlo]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

I think Doc said it was his friend's amp?

Yes, the amp is not mine...

In fact, he has just finished another one, but this time with a Bassman OT and 6L6 tubes, and somewhat more "Fender" cap values. Mine also has a reverb, driven by a 12AT7.

Am gonna be receiving it hopefully by the end of this week.

B

 

[dr.barlo]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

Yes, the amp is not mine...

In fact, he has just finished another one, but this time with a Bassman OT and 6L6 tubes, and somewhat more "Fender" cap values. Mine also has a reverb, driven by a 12AT7.

Am gonna be receiving it hopefully by the end of this week.

B

John,

Here is a pic of mine, the one he just has finished.

How does it look?



B

 

[STRATDELUXER97]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

Nice and tidy inside....Nice job overall on the amp also! Enjoy buddy.

I see probably 3 seperate speaker outs for 4,8,and 16 ohms,maybe an effects loop? Explain more about the back of the amp for us Doc.

Looks also like you have the ability to switch a boost circuit in and out,as I see a 12AX7 near that 1/4" hole...Switchable reverb maybe also? But then I also see pots back there.. ;o)

 

[dr.barlo]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

You've got an eye for these kinds of stuff bro... got it all right. It is the drive channel, the "D" channel...

:yourock:

V4 (with a 12AT7) is for the reverb.

It'll have a footswitch, with two controls for switching channels and boost for either of the channels (the boost is a tone stack bypass by the way, simple but it delivers )...

4, 8, 16 ohm cab outputs... Right on!

The mini toggle next to the on/off and stand-by switches is activating a small fan, with two speed modes.

The pots are for the reverb, resonance, and the 100K pot for the Dumble drive channel. Generally, this last one is a trim pot inside the amp, but we decided to get it out. It will be set somewhere between 40-60K. I guess we could call it a "drive shape" knob. The way I understand it is that it is sort of a master vol (like those in Marshall 2004s) for that channel.

It'll have a loop, series. I intend to use my Mesa V-Twin with this sucker.



B

 

[STRATDELUXER97]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

You've got an eye for these kinds of stuff bro... got it all right. It is the drive channel, the "D" channel...

:yourock:

V4 (with a 12AT7) is for the reverb.

It'll have a footswitch, with two controls for switching channels and boost for either of the channels (the boost is a tone stack bypass by the way, simple but it delivers )...

4, 8, 16 ohm cab outputs... Right on!

The mini toggle next to the on/off and stand-by switches is activating a small fan, with two speed modes.

The pots are for the reverb, resonance, and the 100K pot for the Dumble drive channel. Generally, this last one is a trim pot inside the amp, but we decided to get it out. It will be set somewhere between 40-60K. I guess we could call it a "drive shape" knob. The way I understand it is that it is sort of a master vol (like those in Marshall 2004s) for that channel.

It'll have a loop, series. I intend to use my Mesa V-Twin with this sucker.



B

Sounds like an awesome amp...I've modded alot of amps and have been inside of alot of amps..Guess I kinda know a bit about em.. ;o)

 

[dr.barlo]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

I remember.. That is why I was not surprised at all...



B

 

[Fresh_Start]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

Thanks for sharing - especially the gut shot. Your friend does very nice work! :grin: The layout is very tidy and an interesting mix of turret board with point-to-point construction. The placement of the reverb Send & Return jacks makes a lot of sense from a noise & crosstalk POV. There is a lot of circuitry packed neatly into a relatively small package. Not easy to do well!

If you don't mind, I'd like to ask a few questions:

Is there a reverb transformer hidden somewhere we can't see or does he use a different (IOW not Fender) reverb circuit?

What are the two yellow box-shaped things by the input jack? They look like capacitors but I can't figure out what they'd be doing there.

I don't see any relays. Is the channel switching electronic or hard-wired?

What is the rectangular thing screwed down to the chassis and wedged in between the PT, the bias pot and the filter cap end of the turret board? It obviously needs a heat sink. Bridge rectifier of some sort?

Does that OD pot on the back control the signal attenuation between the two overdrive channel stages? The front panel already has Drive and Level.

Cheers,

Chip

 

[dr.barlo]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

Thanks for sharing - especially the gut shot. Your friend does very nice work! :grin: The layout is very tidy and an interesting mix of turret board with point-to-point construction. The placement of the reverb Send & Return jacks makes a lot of sense from a noise & crosstalk POV. There is a lot of circuitry packed neatly into a relatively small package. Not easy to do well!

If you don't mind, I'd like to ask a few questions:

Is there a reverb transformer hidden somewhere we can't see or does he use a different (IOW not Fender) reverb circuit?

Yes, it is hidden behind the preamp tube with the blue cover, and them RCA jacks from the rever tank.

What are the two yellow box-shaped things by the input jack? They look like capacitors but I can't figure out what they'd be doing there.

I don't see any relays. Is the channel switching electronic or hard-wired?

Those are the relays used for switching. Mounted on a pcb that was drawn and printed specifically for this amp and mounted beneath the main board. 2 switches, one for selecting the channel, and the other for boost on/off. The boost side is simply bypassing the tone stack when active.

What is the rectangular thing screwed down to the chassis and wedged in between the PT, the bias pot and the filter cap end of the turret board? It obviously needs a heat sink. Bridge rectifier of some sort?

That thing is a bridge rectifier 1000 volt 35 amper but not using it fully. That's why as far as know he prefers this over using a 1n4007 on the board. I've asked him about the heat sink (that is why I could not reply to your post that fast), and he is saying its ok. He himself has done it for more than a few times, and none caused any problems...

Does that OD pot on the back control the signal attenuation between the two overdrive channel stages? The front panel already has Drive and Level.

It is the input level trim pot (of the ODS channel) that is generally mounted inside the chasis with a trim pot on "D"-amps. The talk is that Mr. D. is using it (and of course other stuff) to tailor the tone specifically to the person getting the amp. So I did not want to be obliged to take the chasis out every time I want to change this thing... Hence, mounted it in the back of the chasis.

Cheers,

Chip

Hope this answers the questions. And please tell me if not.

And thanks a lot for the nice words.

Best,

B

 

[Fresh_Start]

Re: A DIY Dumble Clone Demo: DLT Amplification Pumble

Doc - thanks so much for a very thorough response!

That is a VERY cool amp, and I am fascinated by the layout. The mix of solid state relays, turret board, and point-to-point construction (IOW mounting components directly on pots, tube sockets, etc.) shows that your friend really knows what he's doing. That mondo bridge rectifier is unusual too but I'm sure he's got good reasons for using it.

Most amateur and semi-professional amp builders either start with a "known good" layout or else they end up with a jungle, cross talk & noise. Having built 4 amps, each with at least a semi-custom layout, I really appreciate all of the careful planning that went into this layout. It's especially hard with a higher gain preamp like Dumbles. Wedging reverb in there without problems is icing on the cake. (Reverb tends to pick up and/or create all kinds of noise and oscillation.)

I confess I didn't pay much attention to the tube complement when I watched the video before. Using 5751 tubes for the preamp and KT-77s for power tubes isn't typical to say the least. Was it designed around 5751s or was that your choice Doc?

The amp shown in the demo is not the same one as shown above - all F&T filter caps and Orange Drops in the demo amp and a few things are relocated. Is the one you showed pics of above the prototype?

The tone through the ODS channel with the Strat neck and MV up high (starting about 6:40) is still my favorite part of the demo. It's a little more raw, more rock 'n roll, than most Dumble clones I've heard and I like it.

Thanks so much for sharing all this with us!

Cheers,

Chip