Dumble Serial number 006X OD50WX

[GPD]

...and these.
CW
ATTACHMENTS
RN65D105K.jpg

Charlie,

Those are definitely "Hens Teeth" in the wild

105K with a 1981 date code...many Dumble fanatics and audiophiles alike would be frothing at the opportunity to get their hands on those.

I find it interesting that HAD migrated to the military parts in the 1970's. He must have been reading a lot of Hi-Fi publications at that time because these types of parts were definitely being praised by a variety of audiophiles in the know. Back in the 1980's when I used to frequent David Hafler's residence...he clued me into the merits of the 60's and 70's military resistors. He kept tons of these resistors in his parts bins. Saul Marantz was hip to them as well.

I do not recall seeing anyone else in the 1970's or 1980's using parts like these in their amps...of course, for anyone making amps in any sort of quantities...it would have been impractical then just like it is now.

Even with surplus inventory availability in the 1970's...nobody likely would contemplate hunting these down and employing them given the supply would have been sporadic for the values needed.

One of the cooler decisions HAD made in my estimation...definitely colors the sound in a significant manner and improves the S-to-N ratio at the same time.

Best Regards,


GPD

[GPD]

Tony Wrote: Here is what I know of ODSR #0060. It is an interesting beast. Cap codes say 78 so it may have started out as a 3rd generation later upgraded to a 4th generation Skyliner with some modifications (Max might know) It has RGU59 throughout as well as Q-line (draloric) in the path and a few Phiers here and there.A mix of plates Mepco ceramics/Electra and the brown Dales. It looks to have been modified to have the OD and clean ratios on the back of the amp. It also has a unique reverb mixing circuit unlike a 2nd generation, green toggle switches and accent knob and ceramic power tube sockets.
Standard 220k/100k OD entrance network.Schumacher Twin Iron choke. Sprague TVA's throughout with 2 cans in the chassis to filter the OD and reverb sections. I've heard mixed reviews of the amp.
What I know

Hello Tony,

#0060 I know very intimately. The Sprague electrolytics generally date to 1981. If you run through the various components in the amp with date codes on them, the newest part in the amp (The 7812 T-I solid-state regulator) dates to 1982...so we know for positive it was re-built from what it was to what it is now no earlier than 1982 and most probably later than 1982. We also know that it was originally built into a more traditional early style ODR (second generation type amp) and then was later modified into what it is now by HAD. You can clearly see that he punched out some of the PEM studs and re-drilled the chassis to fit the V1/V2 board, the Reverb Board and the Polarity Splitter board. He offset them from the standard location where a large singular board used to live. He did this to make room for the additional features.

You can also very clearly see that he drilled the hole at a later point in time for the Presence pot...anyone who's ever drilled aluminum knows what it looks like no matter how careful you are using a drill press. He also used an oddball (smaller bodied pot) for the presence control so it would physically fit the spacing available. Also, the clean and ratio OD pot holes on the back of the chassis were a later addition to the chassis and he actually "peened" the clocking dots like he did on some of his earlier amplifiers. He literally daubed in black paint to the indentations too!

For carbon films, it mostly uses Sprague Q-Lines Flame-proof parts though there is a stray 1970's Draloric in there (non-flame-proof) along with some Archer CF resistors and there are a few Pihers in there as well as you also noted. The metal film parts are mostly expected in the various circuit positions with the exception of V1A/B as these plate resistors are not metal film. The 180K is indeed a MEPCO part (Made long before MEPCO/ELECTRA existed). This is a silicone-oil filled carbon film precision resistor that is hermetically sealed. These were originally developed by Western Electric and can be found in military and telecommunications equipment form the 1950's and 1960's. MEPCO and a couple other companies started making the same spec resistors by the 1960's. The 130K is the same spec part though not made by MEPCO...though it is essentially identical in construction to the MEPCO part. These are extremely oddball parts...the likes of which I've never seen in anything else Dumble built. Being "fixed film" or carbon film, they are not as quiet as the metal film parts he used in most of his amps.

They do, however, being V1 plate resistors, have a gigantic impact on the voice of the amp.

To me, #60 is my favorite of the Dumble circuit designs. The reverb circuitry is curiously odd...it almost sounds like a digital reverb effect though obviously is 100% analog. I find the cleans to be very crisp and three dimensional sounding. I find the OD to be very tasty as well, not as smooth as the later high plate Skyline amps but certainly harmonically complex and pleasing to the ears.

The RG-59? It is not Tandy, it is Columbia P/N 1112 which I have seen in other Dumble amplifiers as well. The white jacketed Coax (which is also used for reverb pan connections which worked out well to determine the capacitance ) I haven't been able to nail down what exactly it is yet. The OD is .161", the inner jacket is .136" which makes it closest to RG-122/U. I don't think it is RG-122/U. The center conductor is silver plated and the capacitance/ft. is rather high for the application at 45.6pF. The closest thing I've found to it is a military communications wire used primarily by the US Navy and not readily available for public consumption.

Years ago, I worked for a company that owned Belden cable and I spent a lot of time in Belden plants. Belden made many specialty cables, just like this for the military. They never had any markings on the jacket either...which is the case with the white coax found in #0060. I reviewed the details of this cable with an old retired Belden engineer buddy of mine that handled all the military spec cabling for 30 years of his career. He assured me it is a specific for the military product but hasn't found anything in his files that matches it exactly...so the jury is still out on exactly what it is. Plenty of white jacketed coax with silver plated conductors available out there but none of it matches exactly...so that'll remain a mystery.

Steve Slater of Apex Jr. fame had a spool of something similar...he sold out of it a long time ago. I checked it out in person, not the same cable but similar in appearance. No markings on the jacket or the spool and Steve had no idea what exactly it was either.

Anyway, I've never heard anything negative from anyone who has played #0060...most seem to love and adore it including the current owner.

Best Regards,


GPD

[Aaron]

Hi GPD,

I built an amp based on the photos from ODR#060. I like this amp compared to the earlier pre-overdrive reverb circuit.
Has anyone played or heard the ODR’s with seperate return levels for clean and overdrive?

Here’s a clip of the ODR I built, iPhone recording though:(
https://youtu.be/EtvPAKYpMSo

Thanks,
Aaron

[GPD]

Max Wrote:IMO the term "generation" doesn't make much sense in regard to Dumble amps with OD and with reverb, and/or tremolo, and/or 150W etc.

Max, well, considering the use of "generation" to classify Dumble products originated by individuals other than Dumble...I think it is possible to correlate certain circuit features or the use of components to a specific generation (as defined by you and others on internet forums). But yes, I agree, with so few of the ODR amps produced (relative to ODS) and the reality that many were modified by HAD over the decades...it becomes difficult to rationalize these ODR amps into the general scheme. The reality, however, is that he was building them at the same time he was building ODS amps and there lies many similarities. He did not give them separate serial number ranges so they sort of fit into a general product family and definitely into windows of time.[/quote]

Max Wrote: And based on the parts used in ODR #0060 I'm rather sure, that Alexander started to build this circuit in late 1979 at the earliest.

Given the serial number is 0060, I would say the amp was likely originally built sometime in the late 1970's...possibly earlier than 1979. I believe it would have originally been like a second generation amp using the oddball Centralab RV4 type 500K Treble pot and it had the singular large pre-amp/reverb board as found on all early ODR's. It allegedly was first built for Jackson Browne and then it came back for modifications...I don't know whether this is true or not but I'm very confident that the amp was likely built out as an early style ODR in the late 1970's.

I also believe the parts originally used in ODR #0060 were mostly removed (if not entirely removed) and he started over from scratch. How do I know this? Well, because he had to knock out PEM studs and re-drill the chassis to install and re-position the new boards he installed. He drilled a number of additional holes too...all of which he had to have done with a drill press. You can also see he used a chassis punch to add a second multi-section can lytic in a spot that previously housed a CalRad relay...the new hole removes the previous punch-out for the relay. The mounting holes for the can lytic were drilled at a later date and the drill bit walked a little bit...so he did this and all the additional holes at a later date. Originally, when this chassis was fabricated (it would have been punched on a punch-press) all holes are precision and cleanly formed. You can clearly see the holes if you had it in front of you to inspect.

Obviously, by the time he rebuilt #60 into what it is today, he required 2 x relays which he mounted on boards much like many other ODS amps that came later. BTW, the Taiko relays he used in this amp are early 1980's parts.

Max Wrote: So IMO the presence control pot on the front might have been in this place from the very beginning (as in many ODS amps with a "transition generation" chassis).

Max, I'm attaching a picture of the very obviously drilled presence control hole...this was definitely not punched when the chassis was made. This hole was added later.

Based on the white teflon coax used for connecting the ratio controls on the back and based on the update of the tone stack from the original "classic" specs to "skyline" specs I'm rather sure, that these mods (skyline stack and ratio controls on the back) are from 1985 at the earliest.

Max, the white jacketed coax is perplexing. Why he chose to use this specific coax in this spot makes me scratch my head. I know the amp was built no earlier than 1982...but when was it last touched by Dumble? Nobody really knows for certain. We also don't really know when Dumble started experimenting with the white jacket coax...we know when it first shows up in ODS amps but we really don't know whether he got his hands on some earlier than this and started experimenting? Much like archaeology...the history gets pieced together from what gets dug up and surfaces.

Best Regards,


GPD

[talbany]

Tony Wrote: Here is what I know of ODSR #0060. It is an interesting beast. Cap codes say 78 so it may have started out as a 3rd generation later upgraded to a 4th generation Skyliner with some modifications (Max might know) It has RGU59 throughout as well as Q-line (draloric) in the path and a few Phiers here and there.A mix of plates Mepco ceramics/Electra and the brown Dales. It looks to have been modified to have the OD and clean ratios on the back of the amp. It also has a unique reverb mixing circuit unlike a 2nd generation, green toggle switches and accent knob and ceramic power tube sockets.
Standard 220k/100k OD entrance network.Schumacher Twin Iron choke. Sprague TVA's throughout with 2 cans in the chassis to filter the OD and reverb sections. I've heard mixed reviews of the amp.
What I know

Hello Tony,

#0060 I know very intimately. The Sprague electrolytics generally date to 1981. If you run through the various components in the amp with date codes on them, the newest part in the amp (The 7812 T-I solid-state regulator) dates to 1982...so we know for positive it was re-built from what it was to what it is now no earlier than 1982 and most probably later than 1982. We also know that it was originally built into a more traditional early style ODR (second generation type amp) and then was later modified into what it is now by HAD. You can clearly see that he punched out some of the PEM studs and re-drilled the chassis to fit the V1/V2 board, the Reverb Board and the Polarity Splitter board. He offset them from the standard location where a large singular board used to live. He did this to make room for the additional features.

You can also very clearly see that he drilled the hole at a later point in time for the Presence pot...anyone who's ever drilled aluminum knows what it looks like no matter how careful you are using a drill press. He also used an oddball (smaller bodied pot) for the presence control so it would physically fit the spacing available. Also, the clean and ratio OD pot holes on the back of the chassis were a later addition to the chassis and he actually "peened" the clocking dots like he did on some of his earlier amplifiers. He literally daubed in black paint to the indentations too!

For carbon films, it mostly uses Sprague Q-Lines Flame-proof parts though there is a stray 1970's Draloric in there (non-flame-proof) along with some Archer CF resistors and there are a few Pihers in there as well as you also noted. The metal film parts are mostly expected in the various circuit positions with the exception of V1A/B as these plate resistors are not metal film. The 180K is indeed a MEPCO part (Made long before MEPCO/ELECTRA existed). This is a silicone-oil filled carbon film precision resistor that is hermetically sealed. These were originally developed by Western Electric and can be found in military and telecommunications equipment form the 1950's and 1960's. MEPCO and a couple other companies started making the same spec resistors by the 1960's. The 130K is the same spec part though not made by MEPCO...though it is essentially identical in construction to the MEPCO part. These are extremely oddball parts...the likes of which I've never seen in anything else Dumble built. Being "fixed film" or carbon film, they are not as quiet as the metal film parts he used in most of his amps.

They do, however, being V1 plate resistors, have a gigantic impact on the voice of the amp.

To me, #60 is my favorite of the Dumble circuit designs. The reverb circuitry is curiously odd...it almost sounds like a digital reverb effect though obviously is 100% analog. I find the cleans to be very crisp and three dimensional sounding. I find the OD to be very tasty as well, not as smooth as the later high plate Skyline amps but certainly harmonically complex and pleasing to the ears.

The RG-59? It is not Tandy, it is Columbia P/N 1112 which I have seen in other Dumble amplifiers as well. The white jacketed Coax (which is also used for reverb pan connections which worked out well to determine the capacitance ) I haven't been able to nail down what exactly it is yet. The OD is .161", the inner jacket is .136" which makes it closest to RG-122/U. I don't think it is RG-122/U. The center conductor is silver plated and the capacitance/ft. is rather high for the application at 45.6pF. The closest thing I've found to it is a military communications wire used primarily by the US Navy and not readily available for public consumption.

Years ago, I worked for a company that owned Belden cable and I spent a lot of time in Belden plants. Belden made many specialty cables, just like this for the military. They never had any markings on the jacket either...which is the case with the white coax found in #0060. I reviewed the details of this cable with an old retired Belden engineer buddy of mine that handled all the military spec cabling for 30 years of his career. He assured me it is a specific for the military product but hasn't found anything in his files that matches it exactly...so the jury is still out on exactly what it is. Plenty of white jacketed coax with silver plated conductors available out there but none of it matches exactly...so that'll remain a mystery.

Steve Slater of Apex Jr. fame had a spool of something similar...he sold out of it a long time ago. I checked it out in person, not the same cable but similar in appearance. No markings on the jacket or the spool and Steve had no idea what exactly it was either.

Anyway, I've never heard anything negative from anyone who has played #0060...most seem to love and adore it including the current owner.

Best Regards,


GPD

Hello GDP..I agree! Dumbles attention to detail in his parts selection to achieve a sound and reliability is IMO a big part of his genius nobody else of the time caught on to or paid much attention to in electric guitar amplification.
Thanks for the drill down on the details of #0060. The date codes I can make out starting at 78 (TVA's OPT) through 82 like you mention. Given this was JB's amp and Dumble was living with Brown at the time the amp was constructed it was probably used as Jacksons custom prototype and more than likely modified while he was with Jackson so your right who knows when and how many times the amp was tweaked or re-built given Dumble was his personal amp tech at the time AFAIK.
Years ago I did Visio on #0060 with the intention of building one but never got around to sourcing the parts and spending the time!. I am not really a big spring reverb guy and prefer the D-lator w/ my outboard gear, you may have just talked me into it!!
Sorry if the pic I posted was misleading as it's not an original ODS. This is an attempt at a version of the Tan Ultrasound (Music Man 700v EL-34) sourcing the parts took months but well worth it!. Thanks to the help of Charlie was able to find the old Dales (mine are 98K) I Love em! Originally the amp was loaded with 1 and 1/2w Phiers in the path got lucky and sourced the Iskras So I heard the amp with both resistors and preferred the ISKRA's I am sure HAD would like them as well. The amp is a total blast to play and very musical.

So with that a couple of quick questions?
1. Was #0060 eventually handed to Bonnie Raitt for a time?
2. Have you ever seen or heard of a Dumble amp with Tanalam loaded bypass caps or were all of them aluminum? (another part I prefer)
3. Here are some hermetically sealed resistors dated 60's are these similar to the Military Carbon resistors that are in #0060 (red one is IRC)
4 have you tried the Iskras?. If so what did you think?
5 Is there a type of coax you prefer in and ODS.
6 Did Dumble use 220P Di-films in the early ODS's (great sounding caps)

Also attached is a hand drawn layout Dumble did of ODSR #13. I assume you would consider this a 2nd generation. This amp had a unique stack 1M Bas 1M treble and the James configuration and the pre OD reverb mix.
Have you played one of these if so how different are they compared to the later #0060.(especially with the sound of the reverb) Btw. I assume 13 was similar to what Lowell George had and the one you posted earlier w/ flexfoam correct?

Thanks and all the best!!

Tony

[Max]

We also know that it was originally built into a more traditional early style ODR (second generation type amp)

IMO we only know for sure, that the current look of the chassis of ODR #0060 is most similar to the look of a "transition generation" ODS chassis. And I have strong doubts, that the chassis of ODR #0060 started its life as a chassis prepared for sliding switches similar to a 2nd generation ODS chassis.

And many of the "transition generation" ODS chassis started their life, (too?), as empty 3rd generation style ODS chassis, that had to be modified by Alexander (additional holes for ratio controls on the back and a small presence control on the front e.g.) in order to prepare a 3rd generation ODS chassis for the then new circuit specs (Standard OD with trigger pot entrance, classic tone stack, ratio control, presence control) you'll find in most of the transition generation and 4th generation ODS amps.

So IMO there's no proof at all, that e.g. the hole for the presence control of ODR #0060 has been drilled after its first original circuit was already completed in this chassis. In my opinion its far more likely, that this amp started its life - just as some of the ODS amps - in a modified 3rd generation style chassis (= "transition generation" chassis) - with a standard OD circuit and a post-OD reverb and with all the typical parts you'll find in a transition generation and 4th generation ODS chassis, too (Sprague Q-Line resistors etc.). So IMO there never was a pre-standard OD circuit or a pre-classic tone stack in the chassis of ODR #0060.

My assumption: Before beginning with the implementation of the original circuit of ODR #0060, the empty chassis was prepared (additional drills etc.) for the then new transition generation and 4th generation circuit specs (standard OD with trigger entrance, presence control, etc.) very similar to the kind of ODS circuit specs you'll find in many of the ODS amps with a transition generation or 4th generation chassis, too.

Cheers,

Max

[talbany]

Max
I don't know if these shots will add to the discussion here but here are some shots I have of the bottom chassis of #0060
Output Transformer looks Dated 13th week of 78. Power (006) is 6th week of either 70 or 80. most likely in 1980.Both a Twin Reverb Schumacher's. There are a few what looks to be pre-punched unused holes in the bottom.
The article here mentions that the amp may have started out as having a classic stack???

https://www.premierguitar.com/articles/ ... e-od-100wr

Hope this helps!

Tony

[talbany]

One More

[Max]

... Output Transformer looks Dated 13th week of 78. Power (006) is 6th week of either 70 or 80. most likely in 1980. Both a Twin Reverb Schumacher's. ... The article here mentions that the amp may have started out as having a classic stack??? ...

Tony, based on the date codes and based on the kind of parts visible on the pictures of ODR #0060 I'm rather sure, that the first original circuit of ODR #0060 was completed in the early eighties. This kind of parts and circuit you'll find in many of the ODS amps with a transition generation and 4th generation chassis, too: Standard OD with "trigger" trim pot entrance, classic tone stack, ratio control(s), presence control, (reverb: post-OD reverb mix).

Then - IMO in the mid eighties at the earliest - the circuit of #ODR 0060 was updated to skyline specs with a mid-switch, just as some of the ODS amps with a transition generation chassis and a 4th generation chassis, too. So IMO the article is correct in regard to the original tone stack specs ("classic") of ODR #0060. In this amp - IMO - never was a version of the "pre-classic" tone stack and the "pre-standard" OD circuit, you'll find in the ODS amps with a 2nd or 3rd generation chassis.

BTW: In regard to the rarer Dumble amps (ODR, DL, SSS etc.) IMO it's not unusual, that Alexander Dumble used an already completed but still empty ODR or DL etc. chassis, and (before the implementation of the elctronic parts) added the chassis-modifications (e.g. closing some holes and drilling some new holes etc.) he needed for the specific functional and tonal specs ordered by some customer and/or suiting Alexander Dumble himself (for whatever specific reason).

All the best,

Max

[GPD]

Tony Wrote: Hello GPD..I agree! Dumbles attention to detail in his parts selection to achieve a sound and reliability is IMO a big part of his genius nobody else of the time caught on to or paid much attention to in electric guitar amplification.

He was ahead of the curve on multiple fronts. When you compare an early ODS’s to the other cascading gain stage competitor (Boogie) it is obvious he was working towards a more controllable and musically viable mousetrap.

Tony Wrote: Sorry if the pic I posted was misleading as it's not an original ODS. This is an attempt at a version of the Tan Ultrasound (Music Man 700v EL-34) sourcing the parts took months but well worth it…

Gotcha…one of your own creations. I like the old MusicMan PT and OT’s…I’ve grafted different tube pre-amps into old MM amps in the past and they generally end up sounding fantastic. I know HAD had used MM iron on some of his amps…doesn’t surprise me in the least…a good choice.
Run the plates up way high and the screens down low…makes for a very big sounding amp. I had some very long discussions on these amps with Tommy Walker when he was still alive…but that’s a different story for another time. Tracy Sands (Bad Cat) was a technician at Music Man back in the 1970’s…another great resource to have discussions with on the topic of those old MM amps.

Tony Wrote: So with that a couple of quick questions?
1. Was #0060 eventually handed to Bonnie Raitt for a time?

Tony, I do not believe this was the case. The purple combo cabinet was offered to her at one point but what chassis was actually installed is unknown. I know that she rejected the combo (chassis unknown) for being too heavy. Greg Bayles (Make’n Music) purchased #0060 in the purple combo cabinet from Jackson Browne. I know for a fact that this cabinet had a different chassis in it at one time as there are 4 extra holes in it (that have been utilized) for a different chassis mounting footprint. You can clearly see, by studying the cabinet, that a different chassis was indeed installed in this cabinet at one time. Anyway, Greg ended up selling #0060 to Bruce Illig (Hillshire Recording Studios, outside of Chicago) in the mid 1990’s. The amp ended up being documented by Chris Barnett (a great guy) was flown out from the Bay Area to Illinois to check out #0060. Bruce, in turn, ended up selling the amp to the current owner. When the amp came into us for analysis…it was in desperate need of power tubes (only making 60 watts RMS into 4 ohms). The electrolytics are old while they still function…you can see a little bit more ripple than would be ideal. The owner wanted to leave them alone being thrilled that a simple power tube change really woke the amp up. One of the Taiko relays was problematic…this had to be replaced. I would say the assembly of this particular amp is rather sloppy and the amp was reasonably dusty on the inside…but hey, it is old so no surprise here. Besides, when Dumble built the amp he surely wasn’t expecting anyone to be scrutinizing his handiwork as closely as it turns out it was.

2. Have you ever seen or heard of a Dumble amp with Tantalum loaded bypass caps or were all of them aluminum? (another part I prefer)

Good question…I’ve obviously seen plenty of tantalum cap’s in original Dumble amps but I don’t recall ever seeing a tantalum cap used in a cathode bypass application.

3. Here are some hermetically sealed resistors dated 60's are these similar to the Military Carbon resistors that are in #0060 (red one is IRC)

IRC MDC’s are most positively carbon film (not metal film) and they are in a molded package but they are not really the same as the ceramic bodied, hermetically sealed, oil-silicone filled parts found in #0060. BTW M = Molded. I haven’t found any other old military resistors that sound quite like the parts found in #0060 other than the correctly constructed parts.

4 have you tried the Iskras?. If so what did you think?

Yes, quite frequently. Obviously, they are well regarded parts and lusted after by Marshall or HiWatt type builders. I like them…and I like them in many instrument and Hi-Fi applications. I also like the old 1960’s and 1970’s Pihers and I also like the 1970’s to very early 1980’s vintage Dralorics. Same goes for Beyschlag and Resista/Roederstein parts. Each brand has its own flavor…all are good but all are different. I know most are fascinated with the Draloric made Sprague Q-Lines with the flameproof coating…and I get it…these resistors definitely have their own sonic signature and I understand the attraction to them.

5 Is there a type of coax you prefer in and ODS.

Well, I really like the Columbia “Flex-Foam” 1389 Coax. Originally, this was intended to be used as microphone cable. What I love about it is the low capacitance/ft. but I also love the spiral wrapped shielding which is super easy to work with (versus braid). Of course, it is really hard to find though Jelle found a bunch of it on E-Bay a few years ago in the form of NOS patch cables. He was kind enough to share in the purchase with me. About 6 months later a buddy of mine stumbled across a 100’ spool of it in the back of a warehouse of an electronics surplus shop that was going out of business. I’ve added this to my inventory and I use it for special projects so I can make it last. For more modern made coax I use a mixture of NOS Carol or Belden products depending on what I require.

6 Did Dumble use 220P Di-films in the early ODS's (great sounding caps) .

I have seen some Di-Films OD’s in some amps in certain spots. The secret to the voice of these OD’s is the proprietary impregnant.

Also attached is a hand drawn layout Dumble did of ODSR #13. I assume you would consider this a 2nd generation. This amp had a unique stack 1M Bas 1M treble and the James configuration and the pre OD reverb mix.

I’ve seen this before and it is really a remarkable find…shocking that the normally guarded HAD would have let this escape. I’m going to avoid the whole “generation” classification but I would suspect this is the first incarnation of the ODR. It is similar (with a few exceptions) to the early style ODR I worked on.

Have you played one of these if so how different are they compared to the later #0060.(especially with the sound of the reverb) Btw. I assume 13 was similar to what Lowell George had and the one you posted earlier w/ flexfoam correct?

I have most definitely played the early ODR…actually, for many hours. I fully comprehend why Lowell George loved it. It sounds like a big fat Fender Twin with more girth in the midrange and obviously, the foot-switchable OD. The OD is that late 1970’s rawer variety and it is impossible to balance the clean and OD levels. The louder you run the amp, the better it sounds. For a slide player it is particularly greasy sounding in OD mode. The reverb? Well…not so fantastic in OD mode (for obvious reasons)…works fine for cleans though the effect can get pretty spacey and downright silly as you play with the controls. It is a very different amp compared to #0060…but this is to be expected, they are very different circuit-wise. Same chassis and same iron…but pretty much everything else is different. I find the #0060 to be a very versatile amp…works well with pretty much any guitar regardless of the pickup compliment.

Best Regards,

GPD

[GPD]

Max Wrote: IMO we only know for sure, that the current look of the chassis of ODR #0060 is most similar to the look of a "transition generation" ODS chassis. And I have strong doubts, that the chassis of ODR #0060 started its life as a chassis prepared for sliding switches similar to a 2nd generation ODS chassis.

Hello Max, here is the problem with speculation…we can try and classify or categorize based on other example amplifiers, however, we really don’t know for positive. I don’t think HAD, himself, is really going to share the details and even if he did…I’d suspect he’s forgotten more about #0060 than he remembers…after all, that was a very long time ago.

I never suggested that #0060 started life as a slide switch ODR chassis. Obviously, this would be impossible given the chassis has the round thru-holes appropriate for mini toggle switches…not slide switches. I would say that the chassis of #0060 started out as the exact same chassis as found in Jackson Browne’s #0058 (Later Rick Vito’s amp) and Jackson’s #0059 ODR. Of course, given the 58, 59 and 60 sequential serial numbers it makes perfectly good sense that #0060 was indeed originally built for Jackson most probably around the same timeframe that #0058 & #0059 were built.

Now here is where it gets interesting with #0060…if you pull out the pots and pay close attention to the inside face of the front panel. Specifically, where the treble pot resides…you’ll see the telltale signs that there was, at one time, a Centralab RV4 type pot installed in this location. These pots used a different toothed washer than the CTS (Fender) pots use in the other locations and it left its mark. How did this mark/pattern end up in the #0060 chassis? Easy, it was once assembled as an earlier style ODR using the RV4 type pot before he rebuilt the amp at a later point in time.

The next evidence I have of #0060 having been built out like an early vintage ODR is the FET board. If you’ve ever compared the early version ODR’s to #0060 you’ll quickly realize that Dumble had to reposition the FET board as the pre-amp board for V1/V2 positioning in #0060 forces the relocation of the FET board to the front of the chassis next to the input jacks. If you had #0060 at your disposal to scrutinize, you find that the chassis still has the holes in it where the original FET board was located. You also find that there are the telltale fastener markings in the aluminum showing an FET board was indeed mounted in earlier location in the #0060 chassis and then was removed when it was converted. If the original position FET board was once installed…that means it cleared the pre-amp board which was also installed at one time.

There are other little details I noted that confirmed to me, without a doubt, that #0060 was indeed assembled as an earlier version of the ODR before it was reconfigured into what it is today. One is that the original reverb RCA jack holes are still where they were when the chassis was originally punched. Dumble drilled two new holes further down, closer to the can lytic. Guess what? The original holes are plugged but you can clearly see that aluminum around these holes once had RCA jacks and fasteners holding them in place. Aluminum is soft…and it marks very easily. Why would these marks be there if the original RCA jack holes were never used? The answer is that the chassis was once setup like an early version of the ODR…the one with the big long singular preamp board. I know it had this board because where the original PEM studs and the central mounting screw/stud once resided show evidence that standoffs and fasteners were used in these locations previously. The PEM studs have to be knocked out to allow the installation of the 3 x Formica V1/V2, Reverb and Polarity Splitter boards. The PEM studs were retained for the HV filter cap board.

But realistically, think about it…#0058, #0059 and #0060 were built for and belonged to Jackson Browne at one time. We know that both ODS and ODR amps utilized the same master serial number list, why would #0058/9 (which are earlier incarnations of the ODR) have been built out as an amp and #60 sitting around serialized as an unused chassis that years later would become what it is today? It makes zero sense and the reality that Jackson Browne owned all 3 amps at one time. But the physical/mechanical evidence that the amp at one time had different components and circuitry installed…is overwhelming. Every inch of this amp had been scrutinized…no stone unturned.

So IMO there's no proof at all, that e.g. the hole for the presence control of ODR #0060 has been drilled after its first original circuit was already completed in this chassis. In my opinion its far more likely, that this amp started its life - just as some of the ODS amps - in a modified 3rd generation style chassis (= "transition generation" chassis) - with a standard OD circuit and a post-OD reverb and with all the typical parts you'll find in a transition generation and 4th generation ODS chassis, too (Sprague Q-Line resistors etc.). So IMO there never was a pre-standard OD circuit or a pre-classic tone stack in the chassis of ODR #0060.

Max, with all due respect, having seen, with my own eyes, that the actual chassis of #0060 shows plenty of evidence that an earlier version of the ODR’s components were indeed installed at one time in the past. FET board, RV4 type treble pot and the reverb jack holes relocated but the original holes used previously…to me, the evidence is overwhelmingly obvious.

Now, what I will say definitively is that I was not present while this amp was being built…of course, neither were you are anyone else on this forum (or any other forum for that matter). Only HAD himself would know and he’s surely not too interested in revisiting the history of this particular amp and sharing it with masses.

Best Regards,

GPD

[Max]

... the actual chassis of #0060 shows plenty of evidence that an earlier version of the ODR’s components were indeed installed at one time in the past ... . FET board, RV4 type treble pot and the reverb jack holes relocated but the original holes used previously…to me, the evidence is overwhelmingly obvious.

Your personal opinion (AFAIU):

At the very beginning - IYO in the mid to late 70ies - ODR #0060 started its life in an unmodified empty 3rd generation style (toggle switches) ODR chassis with a circuit and with parts (Centralab 500KL treble pot, Piher carbon film resistors e. g.) similar to the circuit and the parts shown here (of course with the exception of the reverb circuit and the 100W specs of ODR #0060): https://ampgarage.com/forum/viewtopic.php?f=5&t=12870.

At some later point in time Alexander Dumble modified the original chassis in order to prepare it for the implementation of a nearly completely new circuit similar to the circuit and with the kind of parts (Sprague Q-Line carbon film resistors e. g.) shown here (of course with the exception of the reverb circuit of ODR #0060): https://ampgarage.com/forum/viewtopic.php?f=5&t=12872

Then - again at some later point(s) in time - Alexander Dumble updated this circuit to its current ("skyline") specs, similar to the specs of the circuit shown here (of course with the exception of the reverb circuit of ODR #0060): https://ampgarage.com/forum/viewtopic.php?f=5&t=5719

Correct? If so, then let's compare your personal opinion with

My personal opinion:

At the very beginning - IMO in the early 80ies - ODR #0060 started its life in an already completed but still empty (without "an earlier version of the ODR’s components") 3rd generation style ODR chassis (toggle switches), that - before implementing the first original circuit - Alexander Dumble modified into a version of a "transition generation" ODR chassis in order to prepare this empty 3rd generation style ODR chassis for the implementation of its first original circuit similar to the circuit and with the kind of parts (Sprague Q-Line carbon film resistors e. g.) shown here (of course with the exception of the reverb circuit of ODR #0060): https://ampgarage.com/forum/viewtopic.php?f=5&t=12872

Then - IMO in the mid to late eighties - Alexander Dumble updated this first original circuit to its current ("skyline") specs, similar to this circuit (of course with the exception of the reverb circuit of ODR #0060): https://ampgarage.com/forum/viewtopic.php?f=5&t=5719

So our personal conclusions and opinions in regard to the timeline for the chassis-mods you describe and in regard to the specs of the first original circuit of ODR #0060 are (and perhaps will stay) different:
IYO the chassis of ODR #0060 was modified in the ways you describe some time after its first circuit (pre-standard OD entrance, pre-classic tone stack, etc.) was already completed.
And IMO the chassis of ODR #0060 was modified in the ways you describe before its first circuit (standard OD entrance, classic tone stack, etc.) was implemented.
And IMO our different personal conclusions and opinions are no big surprise in a discussion based on personal speculations (at least to a large extent).
But IMO in regard to the topic of this thread (OD-50WX #006X) it doesn't matter very much, if your or my speculations in regard to ODR #0060 are correct or if we both are wrong. Or do you think, that our different personal opinions concerning ODR #0060 are of great importance in regard to the OD-50WX #006X topic?

BTW:

Up to now I've never ever seen a Centralab 500KL treble pot in an original Dumble ODS or ODR chassis with toggle switches. So if you know an original Dumble ODS or ODR chassis with toggle switches and a Centralab 500KL treble pot inside, pictures of a Centralab 500KL pot inside an original Dumble chassis with toggle switches would be very interesting.

And up to now I've never ever seen an unmodified 3rd generation style (toggle switches) ODR chassis built in the 70ies or 80ies without e. g. additional holes for ratio controls and/or presence controls etc.. All the original "silverface" ODR chassis with toggle switches built in the 70ies or 80ies I've seen up to now are more similar to a silverface transition generation ODS chassis (presence control, ratio control etc.) than to an unmodified 3rd generation ODS chassis. So if you know an unmodified original 3rd generation style ODR chassis (3rd generation style: silverface, toggle switches, and without additional holes e.g. for a presence control and/or a ratio control etc. on their fronts and/or backs) built in the 70ies or 80ies, pictures would be very interesting, too.

Cheers,

Max

[jelle]

It was mentioned earlier that the 70s ODS amps did not have the Tandy black RG59 coax. This is not congruent with the data we have on TAG. Please see attached a pic of a 3rd gen ODS. It is sn 54. I know it does not show the labeling on the coax, but this is the same material I have seen in 80s ODS amps where I was able to read the labeling. I hope this clears up any confusion. jelle

[Max]

... I know it does not show the labeling on the coax, ...

Exactly:

... Just to avoid misunderstandings: Up to now I've never seen a "Tandy" branded coax in an original 1st, 2nd, and 3rd generation ODS chassis.

Source: https://ampgarage.com/forum/viewtopic.p ... 71#p396871

Cheers,

Max

[jelle]

Max, Thanks for that. Looks like we are in agreement. My apologies for not carefully reading your statement. Have a good one! Jelle