Eric Johnson's ODS prototype

[Max]

Can anyone make out each of the controls on the front?

Inputs: above FET - below NOR

Clean channel gain control: below VOLUME

EQ switches: above BRIGHT, above DEEP, above GUITAR - below MIC (technically: Rock-Jazz)

Tone controls: below TREBLE, below MIDDLE, below BASS

OD switch: above MANUAL - below PEDAL

OD gain control: below OVERDRIVE

Master Volume: below LEVEL

Accent switch: above ACCENT

Starve switch: above NORMAL - below STARVE

Pilot Light

Power switches: above OPERATE - below STANDBY, above ON - below OFF, above GROUND

Label (above accent switch, strave switch, pilot light and power switches): OVERDRIVE SPECIAL

Cheers,

Max

[talbany]

Max
Thanks for the clip.. velvet city..The only thing wrong is the clip was too short...

All The Best..

Tony

[qtone]

I wonder if this amp belonged to Steve Bruton or came from his collection..
I know Steve had about 25 Dumble amps he told me that himself.

My question is where did this explosion come from...?

Since Ejs tech has been out with Ben Harper it could have come via
Ben's sources...

The SSS I saw and heard many occasions had the skyline eq as Greg pointed out and therefore the eq of this amp the explosion would be something different indeed.

I bet he can get a great sound from the clean side of the amp boosted
by the tube driver...

If the amp was a tad bright or raw the driver might just balance that out where its just right .

Another tone in the back~line.

Last time I spoke to Eric face to face he mentioned wanting a sss amp only 40 watts and I thought then it would not be the same jangle as the 150 had.

Maybe 40-60 watts he said. He was more concerned about keeping his hearing issues down at that time...

Eric said he thought it was the Twins that took his hearing out..
I think his hearing issue is better now though.

Ill speak with his tech and see about what he knows about the explosion amp..


I bet since he has been a long time buddy of Ben Harpers that they could have scared this Dumble up from his camp.

[Max]

My question is where did this explosion come from...?

EJ's amp that is the topic of this thread is no "Explosion" amp but a 1st generation ODS. AFAIK the "Explosion" prototypes did have a three step OD switch (OFF, Explosion 1, Explosion 2) looking similar to the "OVERDRIVE" switch of the Overdrive Deluxe on the attached picture from Rob Livesey's site.

Cheers,

Max

[talbany]

Max
Yeah I noticed the 3 pos switch and wondered about that..Max so it is basically off/clean/OD correct!!..Funny on this particular OD Deluxe the funky 3 resistor OD entrance is built on the relay..From what I can make out very similar to Skyliner stack .01 mid cap/ James config on bass/ no J/R switch and a funky 82k slope resistor..Looks to be a low plate w/5uf throughout very similar to a 2nd generation (without AT in PI) but with 1st generation parts..Not to change the subject here but do you know and or in your opinion was this particular ODD a variant or similar in design and topology to either Explosion/1st generation/2nd generation..

THANKS!!

Tony

[ToneMerc]

Max.............Not to change the subject here but do you know and or in your opinion was this particular ODD a variant or similar in design and topology to either Explosion/1st generation/2nd generation..
Tony

Tony, that is very good question as I've been pondering this exact same issue. Also, I been wondering what exactly were the preamp voltage ranges in the very early ones and in the ODD and 004, were the PI tubes 12AT7's.

TM

[talbany]

Max.............Not to change the subject here but do you know and or in your opinion was this particular ODD a variant or similar in design and topology to either Explosion/1st generation/2nd generation..
Tony

Tony, that is very good question as I've been pondering this exact same issue. Also, I been wondering what exactly were the preamp voltage ranges in the very early ones and in the ODD and 004, were the PI tubes 12AT7's.

TM

TM
I can't say for certian about the very early explosion and 1st generation amps (however this ODD looks to be very similar to it's 2nd generation cousin accept for 12AT PI) Perhaps Max can advise..AFAIK Dumble recommended the V1 voltages to be between 190-200v in his 2nd generation amps..
Also remember we as builders have the luxury of experimenting around with different voltages..My advice is this.. Some early 2nd 1st gen amps sound wonderful to me run around 185 -190 (There is a big difference between 185 and 200v V1 in these amps BTW) It really is kind of subjective similar to tube types..IMHO it's really worth the effort to sweep through some voltages here as you might find you like V1 run at 185v on that particular amp..
If you do several of these and get yourself trained to what and how those lower voltages effect tone/feel etc you then don't need to sweep every amp as you will just know that you would prefer to run that amp lower/higher,whatever..
FWIW..I prefer the older gen amps with the 3 resistor OD entrance network to be run on the lower end or close to 185 as possible (not so concerned about low end content in OD) and the later 220k OD trigger amps run up around 200v..

Hope This Helps!!

Tony

[qtone]

Ah I was told it was an explosion prototype..
My bad

[qtone]

As far as amp placement and the Dumble or any dirty rhythm amp goes
Eric has done that for years and I think it cuts down hum between multiple amps.... proximity noise and hum is eliminated somewhat if they are set this way.

There is a sonic reason for it...

[Max]

This you find (from left to right) on the front plate of one of the top loaded "Explosion" prototypes I know of:

1 (on the left on the top input)

2 (on the left of the input below)

VOLUME (below the knob)

BRIGHT (above the switch)

DEEP (above the switch)

GUITAR (above the switch), MIC (below the switch)

TREBLE (below the knob)

BASS (below the knob)

EXPLOSION (below the knob = three step switch), N, 1, 2 (above the knob = three step switch)

LEVEL (below the knob)

ACCENT (above the switch)

OPERATE (above the switch), STANDBY (below the switch)

ON (above the switch), OFF (below the switch)

GROUND (above the switch)

Pilot Light

AFAIR the functions of the EXPLOSION switch are: N = Off, 1 = first OD gain level, 2 = second (higher) OD gain level.

I don't know the circuit details of the Explosion prototypes.


Overdrive Deluxe:

AFAIK this Overdrive Deluxe amp on the picture from Rob Livesey's site is a special custom made amp from the early seventies and not one of the late sixties "Explosion" prototypes for the ODS amps:

https://tubeamparchive.com/viewtopic.ph ... 555#108555


Circuit details of 1st and 2nd generation amps:

AFAIK the original circuit of the 2nd generation amps is documented (no goop and some known specimens seem still to be in their original condition).

But concerning the original circuit details of the 1st generation amps AFAIK only some speculations are known (very few known specimens and some of these known specimens may perhaps have been updated by Alexander at some point).


Tone of 1st generation amps:

1st generation slide tones are easy to find (David Lindley). Examples for the tone of a 1st generation amp used for other playing styles than slide are hard to find.

Because of this I've posted some examples for the tone of a 1st and 2nd generation amp used by the same player (Charly Bonat). If I'll find some time I'll try to post some more 1st generation clips. Or you listen to the album "Angel Wings" by Harry Marte on CD (electric guitar tracks on this CD played by Charly Bonat with a 1st generation ODS):

http://www.audioty.com/sounds/marte.html for previews you can click on the song titles.

Here's a video of one of the songs from this CD. There you hear Charly Bonat using a 1st generation ODS:

http://www.myspace.com/marteharry/video ... g/32960024

Cheers,

Max

[ToneMerc]

Max thanks as always for your enlightenment.

TM

[talbany]

Max
Thanks!!

T

[bcook]

Max
Thanks!!

T

Second that. Max, is there a big volume jump from 1 to 2?

[boldaslove6789]

Thanks again (just the Fax) Max! I think I speak for everybody when I say we all appreciate your time with all these details.

[qtone]

This you find (from left to right) on the front plate of one of the top loaded "Explosion" prototypes I know of:

1 (on the left on the top input)

2 (on the left of the input below)

VOLUME (below the knob)

BRIGHT (above the switch)

DEEP (above the switch)

GUITAR (above the switch), MIC (below the switch)

TREBLE (below the knob)

BASS (below the knob)

EXPLOSION (below the knob = three step switch), N, 1, 2 (above the knob = three step switch)

LEVEL (below the knob)

ACCENT (above the switch)

OPERATE (above the switch), STANDBY (below the switch)

ON (above the switch), OFF (below the switch)

GROUND (above the switch)

Pilot Light

AFAIR the functions of the EXPLOSION switch are: N = Off, 1 = first OD gain level, 2 = second (higher) OD gain level.

I don't know the circuit details of the Explosion prototypes.


Overdrive Deluxe:

AFAIK this Overdrive Deluxe amp on the picture from Rob Livesey's site is a special custom made amp from the early seventies and not one of the late sixties "Explosion" prototypes for the ODS amps:

https://tubeamparchive.com/viewtopic.ph ... 555#108555


Circuit details of 1st and 2nd generation amps:

AFAIK the original circuit of the 2nd generation amps is documented (no goop and some known specimens seem still to be in their original condition).

But concerning the original circuit details of the 1st generation amps AFAIK only some speculations are known (very few known specimens and some of these known specimens may perhaps have been updated by Alexander at some point).


Tone of 1st generation amps:

1st generation slide tones are easy to find (David Lindley). Examples for the tone of a 1st generation amp used for other playing styles than slide are hard to find.

Because of this I've posted some examples for the tone of a 1st and 2nd generation amp used by the same player (Charly Bonat). If I'll find some time I'll try to post some more 1st generation clips. Or you listen to the album "Angel Wings" by Harry Marte on CD (electric guitar tracks on this CD played by Charly Bonat with a 1st generation ODS):

http://www.audioty.com/sounds/marte.html for previews you can click on the song titles.

Here's a video of one of the songs from this CD. There you hear Charly Bonat using a 1st generation ODS:

http://www.myspace.com/marteharry/video ... g/32960024

Cheers,

Max

Thanks for clearing that up learning alot here.