New user intro, and where to start??

[Bob-I]

Bob

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

Damn, that'll be a lot of typing.

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

What does "CKT" stand for?

Circuit

What does 90 's values mean ?

Dumble used different values for the 90's ckts. Look at the ODS101 schematics in the files sections.

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

No, 1/2 watt is fine, but use Vishay Dale RN65 series resistors. It really makes a difference in the upper mids and highs. They're simply clearer and richer sounding.

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

Yes and no, anything over 400V is fine, but use metalized polyprop caps, like the Orange drop 6PS or Xicon MPP series caps. I prefer the Xicon MPP 600V caps. pF value caps should be ceramic 1KV.

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

Regards

Yes.

[Bob-I]

Ok, my amps.... 5 are actually mine, one was sold.

1. I bought a dead Crate 1x12 combo for $5 on ebay, gutted it and built a Hybrid A. I used Bassman replacement iron and 2x6V6's. Today it has an Eminence Swamp Thang in it and sounds great, very complex mids.

2. A friend gave me an Allen old flame head cabinet. I built a 3 channel 50 watter using Bassman iron. There's a Fender Super Reverb clean channel, Dumble clean and HRM ODS and a 2 tube reverb. 2x6L6's and 6 12AX7's. Tons of bottom end.

3. I bought a Princeton chassis and PT with a Deluxe OT. It's the Hybrid A schem in a small head cab and a matching 1x12 with a Red White and Blues. Really aggressive and punchy.

4. Weber 6A40 kit (Super Reverb) modded to use the normal channel as an ODS channel. Used Hybrid values. I just need to add the relay's.

5. Peavey Classic VTX transplant, $25 on ebay. This was a hybrid SS preamp and 2x6L6 output. I gutted it and used the iron chassis and cabinet to build an HRM. I have 2 Eminence Tonkers in it now. Very fat and rich sounding amp. I compared to a 90's Dumble a few weeks and and was very pleased.

6. I built a Hybrid A using EL-34's for a friend. I used Marshall replacement iron and made it very aggressive by tweaking the snubbers and NFB.

I have another Peavey chassis that I'll use for an HRM with an ECL86 for reverb.

[hipbluescat]

Bob

Thank you again especially for the typing that you have done.

I see you have had alot of fun with these amps !

For the electrolytic capacitors I am thinking of using Sprague atom cap than the Illinois power supply cap.

For the small capacitors I think that ceramic small caps would be better than the Silver Mica because they would tend to have more of a open sound.

I also read one of your other threads on speakers and below is your comments

Funny, I was thinking the same thing. I have 3 cabinets and 2 combo's now.

2x12 partial open back with Celestion G12H80's. Very flat response to my ears. Punchy bottom end and smooth mids, the highs are nice but not too pronounced like many Celestions. Cleans are bright and articulate, OD is smooth and singing. This is my reference cabinet, I shoulda bought more when Avatar was blowing them out at $50.

1x12 closed back with Eminence Red White and Blues. A bit more mids than the Celestions, and the heighs are getting better as it breaks in. A tad muddy though, I need to really open up the presence to get the shimmer.

1x15 EVM in a closed back. This is quickly becomming my favorite cabinet. I put it together for bass but with the Dumbles it sounds excellent. Very little color, tons of bottom and nice shimmering highs.

2x12 Combo with Eminence Tonkers. These are my only 16 ohm speakers. Very aggressive and loud. A bit peaky in the low mids, but plenty of bottom and punch.

1x12 Combo with a JBL D-120 paper dome. The jury's out on this one. I suspect this old Crate cabinet is at fault for the almost muffled tone as every speaker in this cab has sounded poor. The speaker is punchy with a lot of bottom but pretty muffled in the mids. Again the cabinet


Others I've tried.

Weber 1230-55... it's listed on ebay now. Not at all right for these amps, not at all right for me. Very peaky upper mids, typical Marshall type speaker. Blech.....

Jensen C12N re-issue. This speaker sounds ok in a Fender type amp, terrible with a Dumble clean or dirty. No bottom, no mids, just tinny highs.

Weber Thames. Very pronounced mids, weak on the bottom end and highs.

For the Robben Ford sound I was thinking of using two 12 inch Celestions not the Eminence Red White and Blues speakers. I am thinking of getting a box with the back ported.

For the Larry Carlton sound I was thinking of using one 12inch speaker in a enclosed box.

Could the 15 inch EV speaker do both the Robben Ford and Larry Carlton sounds ?

Could one amp using different speaker box achieve this ?

Regards

[Bob-I]

Bob

Thank you again especially for the typing that you have done.

I see you have had alot of fun with these amps !

I love 'em... and I'm happy to "pay it forward"

For the Robben Ford sound I was thinking of using two 12 inch Celestions not the Eminence Red White and Blues speakers. I am thinking of getting a box with the back ported.

I agree, they'll be brighter and more cutting like Robben likes.

For the Larry Carlton sound I was thinking of using one 12inch speaker in a enclosed box.

Again, I agree. Get as clean and hi-fi a speaker you can. Larry uses old EVM12L's. Weber's Michigan series are supposed to be close but I don't deal with Ted anymore so I don't know.

Could the 15 inch EV speaker do both the Robben Ford and Larry Carlton sounds ?

No, not at all. I like it a lot but it's unique and doesn't sound anything like Larry or Robben.

Could one amp using different speaker box achieve this ?

Regards

I'm not sure. I'm not really after these tones, more after my own tone that I've been looking for for 100 years... ok 35 years.

[Mickey_C]

Hi Moss - good to see you here too!

...

Okay everybody - that's a whole lot of information!

Are there soundclips of each? Which circuit would be the most "classic" Dumble sound, of "song and legend" so to speak?

Mickey

[George Adzich]

Mickey,

Your amps look great. How has the business been going.

I am glad you asked about the JFET switching. I used it on a prior build and it works great. I think it is the most "elegant" switching method.

My dumble is still on the bench and I only need a few more hours to finish the overdirve section.

I have been over-analyzing the "Shunt" switching on a Dumble for a long time. I was hoping somebody else had also tried it. I would be glad to share my experiences with you.

I followed Kevin O'Connors guidance, but he leaves out some important parts of the circuit - like de-bouncing the swicthes. We can share data on this post or you can contact me directly.


Cheers,

George

[Tonegeek]

Welcome Mickey_C. Your amps look great - some of the most visually appealing I have ever seen. I am in the middle of my first Dumble build so won't be much help to you (unless you learn from my mistakes - ha!) Only suggestion I have is to read all the posts in this forum and maybe the general discussion forum as well. Critical tone shapers appear to be cap and resistor types ex. PS (NOT 716) or Xicon caps in some areas, also 1 watt carbon film vs 1/2 watt (for less hiss), grounding scheme, plate voltages, Neg feedback values (different for 50 vs 100 watters).
Good luck.

Whit

[glasman]

Hi Moss - good to see you here too!

...

Okay everybody - that's a whole lot of information!

Are there soundclips of each? Which circuit would be the most "classic" Dumble sound, of "song and legend" so to speak?

Mickey

Hi Mickey, nice to see you around the boards.

Most every Thursday night ( and some Sundays) I have one of my 100W amps that has all of the various modes Stack, no stack 70's,80's,90's voicing etc. It is at the famous Sams at the corner of Ray Road and Alma School in Chandler.

You are more than welcome to stop by and take it for a drive. Then you can decide what direction to go with your amp.

For me, I would stick with relays. I would be afraid of the jFets screwing with the inpedance and cutoff frequencies of the various stages. These are critical to getting the right sound.

If you want you can also stop by me casa. Give me a call

480 898-1058 Home Office
602 677-7028 Cell Phone

Gary

[dogears]

Floating baffle, oval ported back w/ the new Heritage G1265 Celestions fro the RF thing.

EVM12L in a closed back, but tuned or detuned front ported box. THis is important. The EVM sounds best to me with a closed back, but tuned.

I am near Philly and have both styles here to sample if you are somewhat local.

Bob

Thank you again especially for the typing that you have done.

I see you have had alot of fun with these amps !

For the electrolytic capacitors I am thinking of using Sprague atom cap than the Illinois power supply cap.

For the small capacitors I think that ceramic small caps would be better than the Silver Mica because they would tend to have more of a open sound.

I also read one of your other threads on speakers and below is your comments

Funny, I was thinking the same thing. I have 3 cabinets and 2 combo's now.

2x12 partial open back with Celestion G12H80's. Very flat response to my ears. Punchy bottom end and smooth mids, the highs are nice but not too pronounced like many Celestions. Cleans are bright and articulate, OD is smooth and singing. This is my reference cabinet, I shoulda bought more when Avatar was blowing them out at $50.

1x12 closed back with Eminence Red White and Blues. A bit more mids than the Celestions, and the heighs are getting better as it breaks in. A tad muddy though, I need to really open up the presence to get the shimmer.

1x15 EVM in a closed back. This is quickly becomming my favorite cabinet. I put it together for bass but with the Dumbles it sounds excellent. Very little color, tons of bottom and nice shimmering highs.

2x12 Combo with Eminence Tonkers. These are my only 16 ohm speakers. Very aggressive and loud. A bit peaky in the low mids, but plenty of bottom and punch.

1x12 Combo with a JBL D-120 paper dome. The jury's out on this one. I suspect this old Crate cabinet is at fault for the almost muffled tone as every speaker in this cab has sounded poor. The speaker is punchy with a lot of bottom but pretty muffled in the mids. Again the cabinet


Others I've tried.

Weber 1230-55... it's listed on ebay now. Not at all right for these amps, not at all right for me. Very peaky upper mids, typical Marshall type speaker. Blech.....

Jensen C12N re-issue. This speaker sounds ok in a Fender type amp, terrible with a Dumble clean or dirty. No bottom, no mids, just tinny highs.

Weber Thames. Very pronounced mids, weak on the bottom end and highs.

For the Robben Ford sound I was thinking of using two 12 inch Celestions not the Eminence Red White and Blues speakers. I am thinking of getting a box with the back ported.

For the Larry Carlton sound I was thinking of using one 12inch speaker in a enclosed box.

Could the 15 inch EV speaker do both the Robben Ford and Larry Carlton sounds ?

Could one amp using different speaker box achieve this ?

Regards

[hipbluescat]

dogears

I thankyou for your offer but I live in Australia.

On the celestion website there is no G12H 65 but there is G 12 H 30. Will these do the same job?

Also there is a Anniversary model and a Hertiage model of the G 12 H 30.

Does anyone know what the difference is in these two speakers. The Hertiage is also double the price.

Regards

[Bob-I]

On the celestion website there is no G12H 65 but there is G 12 H 30. Will these do the same job?

No, they're completley different speakers

[hipbluescat]

Bob

I have a tough question to ask you.

What is the difference between the G12H Hertiage and Anniversary speaker from Celestion.

What are professional musicials buying and what is the real difference when placed in a 65 Deluxe Reverb amp ?

Regards

['67_Plexi]

Mickey, you're obviously a Marshall guy

Asking which Dumble is the classic tone is rather like asking what a Plexi tone is. There's many.

In general they are all very sensitive to your playing style and pick technique moreso than many other amps. Set up well, the notes should bloom into feedback even with a relatively clean tone. The HRM is a bit more gainy with a more modern feel than the non-HRM. The HRM clean sound is virtually unimaginable from a set of EL34's. It's the best of any amp I've played.
The real non-HRM Dumble I played was a very harmonically complex amp that was smooth yet extremely aggressive. None of these amps could be called forgiving. However, the HRM has way more gain than what most people imagine it to have, but it will remain clear and articulate and highlight any mistakes and playing flaws in a big neon sign !

The commnon denominator with all of the Dumbles circuits is the tweaking. Basically you have to tweak them to the playing style and guitar. Dumble made no two amps exactly the same, so getting all hung up about using exact make of parts for everything can be pointless.
There are a few critical areas where component selection is very important, there are also some pretty critical preamp plate voltages to aim for. But apart from that, he used pretty bog standard Fender trannys for the 6L6 models and off the shelf US made trannys from Magic Parts for the HRM's. The feedback circuit should be designed for the trannies you use. The ref circuits on this site give you some reasonable starting values, but every one I've built I've had to tweak the feedback resistor (amongst many other things).

Looking at the amps you currently sell, this is very different (but I'm sure you know that already) and I'm sure you've built more complex ones before anyway. Relay selection, relay power supply and cable dress are all very critical if you want a noise free channel switcher. The grounding scheme is also critical, use Dumbles, don't even bother trying a Marshall or any other scheme, nothing else is anywhere near as effective. The HRM's require special attention in the relay area, many people have had popping problems. However they can be made dead silent with a little bit of thought. All the information can be found on this site. You sometimes just have to dig deep for it.

Good luck and enjoy your first build.

Just post any questions, several folks on here have a pretty deep understanding of these amps.

Kind Regards,
Alan Phillips
Carol-Ann Custom Amplification