Ben Harper Dumble "Collection"

[CHIP]

The lead dress on V1 and V2 pin 3 cathodes runs around the front of the tube socket instead of around the rear.
Isn't this different from most ODS's

[CHIP]

The inside of Ben Harpers ODS pictured above..Low Plate Classic!!

Gary.. Great stuff..Thanks!!..
Attn K-Mart shoppers.. Blue light special on Daves ODS covering..

Tony

That looks like one of Jackson Brownes amps. The only I every saw with that configuration on the OD plate loads. Hmmm could it be..

Another nugget of non-sense. Talking with Jackson Browne last year after his show in Vegas and we got talking about heir Dumble. His said once of his biggest complaints with the big guy was he could never make two amps that sounded the same (David L was nodding in agreement). The second thing both of them told me is that neither would EVER leave an amp, they will sit and wait for the repair or mod to be completed.

The comment about the big guy couldn't make 2 amps that sounded the same, is quite a profound statement, because a lot of builders. myself included, are trying to acheive a "clone" of some of HAD's best sounding amps. Hmm.
Something for Stephen Hawking to ponder.

[stevlech]

Good call on the cathode wiring, Greg

[G. Hoffman]

A bit off topic, but if you don't get Fretboard Journal, you should. It is one of the best guitar magazines ever published, and is well worth its (admittedly high) price. Every article they've ever published is excellent, their photography is wonderful (they even made my dad look good!), the paper is seriously archival quality, and the ads are all in either the front or back of the magazine, leaving the editorial content free of interruptions. This is one magazine which is decidedly NOT a "rag."


Gabriel

[thyx]

The comment about the big guy couldn't make 2 amps that sounded the same, is quite a profound statement, because a lot of builders. myself included, are trying to acheive a "clone" of some of HAD's best sounding amps. Hmm.

Yep. And I challenge anybody to make two ODS-style amps to sound exactly the same. I don't think anybody can. Pushing the gain that high reveals all the differences in the tubes more-so than lower-gain amps. You'd have to clone the tubes...all of them...if you expected to get the same sound out of a clone amp.

[Structo]

The lead dress on V1 and V2 pin 3 cathodes runs around the front of the tube socket instead of around the rear.
Isn't this different from most ODS's

The thing about the tube wiring, he has the sockets oriented so that the first triode is the first stage. (pins 1,2 and 3)

In other words the gap between the pins 1 & 9 is towards the board whereas most the other amps we have seen has it so the gap faces the rear and the second triode is the first gain stage.

[glasman]

The comment about the big guy couldn't make 2 amps that sounded the same, is quite a profound statement, because a lot of builders. myself included, are trying to acheive a "clone" of some of HAD's best sounding amps. Hmm.

Yep. And I challenge anybody to make two ODS-style amps to sound exactly the same. I don't think anybody can. Pushing the gain that high reveals all the differences in the tubes more-so than lower-gain amps. You'd have to clone the tubes...all of them...if you expected to get the same sound out of a clone amp.

I agree it is a lot of work to keep amps in the same tonal range. Tubes are the big variable, I test every tube I use and bin them based on measured parameters for various positions in my amps. Tubes that are outside the "norm" are returned for replacements.

Components are handled the same way. Caps are meausred for value, ESR, polarity and dissipation. Pots are measured and binned, any pots that are outside of 5% nomimal go into the scrap heap. Fallout on pots (I buy 2500 at a time) is about 18 out of 100 on 1Meg 30% (less on lower values). Carbon film and metal film resistors are hand selected at the time of amp build.

Getting way off the subject.

Back to subject.

To Talbany,

Yes Ben and David are good friends and David frequents Bens family stringed instrument shop (I think they both live in the same town). I would think that might reinforce the JB conneciton.

Gary

[ChrisM]

The comment about the big guy couldn't make 2 amps that sounded the same, is quite a profound statement, because a lot of builders. myself included, are trying to acheive a "clone" of some of HAD's best sounding amps. Hmm.

Yep. And I challenge anybody to make two ODS-style amps to sound exactly the same. I don't think anybody can. Pushing the gain that high reveals all the differences in the tubes more-so than lower-gain amps. You'd have to clone the tubes...all of them...if you expected to get the same sound out of a clone amp.

I agree it is a lot of work to keep amps in the same tonal range. Tubes are the big variable, I test every tube I use and bin them based on measured parameters for various positions in my amps. Tubes that are outside the "norm" are returned for replacements.

Components are handled the same way. Caps are meausred for value, ESR, polarity and dissipation. Pots are measured and binned, any pots that are outside of 5% nomimal go into the scrap heap. Fallout on pots (I buy 2500 at a time) is about 18 out of 100 on 1Meg 30% (less on lower values). Carbon film and metal film resistors are hand selected at the time of amp build.

Getting way off the subject.

Back to subject.

To Talbany,

Yes Ben and David are good friends and David frequents Bens family stringed instrument shop (I think they both live in the same town). I would think that might reinforce the JB conneciton.

Gary

Very interesting stuff Gary! Always interesting to see how the guys who build these in numbers are doing it. You must have some nice test equipment!

[dreric]

The comment about the big guy couldn't make 2 amps that sounded the same, is quite a profound statement, because a lot of builders. myself included, are trying to acheive a "clone" of some of HAD's best sounding amps. Hmm.

Yep. And I challenge anybody to make two ODS-style amps to sound exactly the same. I don't think anybody can. Pushing the gain that high reveals all the differences in the tubes more-so than lower-gain amps. You'd have to clone the tubes...all of them...if you expected to get the same sound out of a clone amp.

Not to take the well beaten horse out of the barn again but.............

I think the statement above applies to any pre-PCB tube amp and to a lesser degree post-PCB amps. Even the big companies, Fender, Marshall, Ampeg who were mass producing amps with uniform construction methods and relatively consistent material selection have the "each one sounds different" within the same model syndrome. Maybe not to the same degree as HAD's amps but the variation is significant.

I think its also important to remember that all of the "first generation, second, thrid, Classic" classification of HAD's work was done my members of this forum (mostly Max) as a study of HAD's work over the scope of his career. Historically, this is convenient in helping US to
understanding HAD's different "periods" but I think it's more an artificial overlay on a design or amp concept that HAD was clearly evolving over 30+ years.

I don't think HAD really ever wanted to make the same amp twice. My observation is that he operates like an artist rather than a "business man".

I sympathize with JB and Lindley, both artists asking another artist to make another amp just like the one before. It my be easier to have them write exactly the same song, a second time.

Eric

[glasman]

Very interesting stuff Gary! Always interesting to see how the guys who build these in numbers are doing it. You must have some nice test equipment!

I have done pretty well in the test equipment area over the last couple of years. Off the top of my head I don't remember all of the model numbers

Scopes

Tektronix 250Mhz Digital
Protek 100Mhz analog
Had a Fluke scope meter for a long time, but give it to Gil Ayan a while back.

You know I am still "old school" and I still prefer an old analog scope to this new modern things.....

Bench Meter

Keithley 2000 DMM - Supports both 2 and 4 wire resistance measurements, damn thing measures everything..... to 4 places.

LCR Bridge

Quadtech 1750T with transfomer measuring adapter. HIGHLY recommended but a little spendy for the casual user.

Spectrum Analyzer

Ono Sokki CF-5220 FFT analyzer
Agilent 13??? FFT analyzer.

Both measure DC to about 105Khz
I use these for measuring response of all stages. I keep reference traces on file and can compare them overlayed to check for consistancy. I keep traces on all amps that are shipped for future reference.

The Ono Sokki also measures THD and it makes it nice for adjusting the PI trimmers.

Power Supplies

Power design Triple source LV supply
Schlumberger/Heath HV bench supply (0 to 400V, 0 to -150v and filaments)

Misc
various homebuilt cap subbers
dummy loads from 100 to 500W
A cool little box that has four 6 posiiton switches that allows changing plate and cathode resistors in circuit to tweak for different gain structures and tonal effects. Has positions for 100K, 120K, 150K, 180k, 200K, 220K with corresponding cathode resistors.
Hickok 752 tube check
Home built tube tester that I use to do real time analyse with my FFT analyzers. Allows looking at gain and response curves.


Gary

[glasman]

I don't think HAD really ever wanted to make the same amp twice. My observation is that he operates like an artist rather than a "business man".

I sympathize with JB and Lindley, both artists asking another artist to make another amp just like the one before. It my be easier to have them write exactly the same song, a second time.

Eric

This is Exactly the way they both made it sound. Every amp had to have its own unique voice..... and HAD always had something new he wanted them to try (and buy).

[dreric]

Very interesting stuff Gary! Always interesting to see how the guys who build these in numbers are doing it. You must have some nice test equipment!

I have done pretty well in the test equipment area over the last couple of years. Off the top of my head I don't remember all of the model numbers

Scopes

Tektronix 250Mhz Digital
Protek 100Mhz analog
Had a Fluke scope meter for a long time, but give it to Gil Ayan a while back.

You know I am still "old school" and I still prefer an old analog scope to this new modern things.....

Bench Meter

Keithley 2000 DMM - Supports both 2 and 4 wire resistance measurements, damn thing measures everything..... to 4 places.

LCR Bridge

Quadtech 1750T with transfomer measuring adapter. HIGHLY recommended but a little spendy for the casual user.

Spectrum Analyzer

Ono Sokki CF-5220 FFT analyzer
Agilent 13??? FFT analyzer.

Both measure DC to about 105Khz
I use these for measuring response of all stages. I keep reference traces on file and can compare them overlayed to check for consistancy. I keep traces on all amps that are shipped for future reference.

The Ono Sokki also measures THD and it makes it nice for adjusting the PI trimmers.

Power Supplies

Power design Triple source LV supply
Schlumberger/Heath HV bench supply (0 to 400V, 0 to -150v and filaments)

Misc
various homebuilt cap subbers
dummy loads from 100 to 500W
A cool little box that has four 6 posiiton switches that allows changing plate and cathode resistors in circuit to tweak for different gain structures and tonal effects. Has positions for 100K, 120K, 150K, 180k, 200K, 220K with corresponding cathode resistors.
Hickok 752 tube check
Home built tube tester that I use to do real time analyse with my FFT analyzers. Allows looking at gain and response curves.


Gary

I have a radio shack meter

[glasman]

I have a radio shack meter

I started with a Fluke 77 and that was it..... been collecting equipment ever since.....

[vibratoking]

Components are handled the same way. Caps are meausred for value, ESR, polarity and dissipation. ...

Can I ask how do you measure a cap for dissipation?

[glasman]

Components are handled the same way. Caps are meausred for value, ESR, polarity and dissipation. ...

Can I ask how do you measure a cap for dissipation?

It is actually a function of the Quadtech unit. Dissipation is the reciprocol of the Q of the cap. Polyster caps run a Q of about 600, Polyprops run in the 6000 range.

Q is defined (as I remember) XL / Rs