ODR Advise needed

[Runaway J]

Hi everybody !

This is my first writing here, but before I start I’d like to tell you that I’m really blown away by so much enthusiasm and superb craftsmanship I found here on this forum.
(Please excuse my humble English, I’m from Germany and havn’t had much English practice since some years). I urgently need some adwise for my Dumble clone project, so here’s my story:

I own an old hardwood top and a 2x12 speaker enclosure from ‘79 or so (mahagony + wicker cane). Until ’82 the top contained an original Dumble ODR. Below is a (cheap) picture of that set.

Unfortunately the amp is gone, I only own the empty top and the speaker enclosure, loaded with only one Altec. (You wanna know what happened to the amp ? I can later post it if someone is interested). Anyhow …I can hear the empty top screaming for tube heat - so I want to bring some life back into it.
I already collected as much information as I could (mostly) from this fantastic forum, bought some parts, made some drawings, but there are still a lot of questions left. It would be great if you could give me some advise.

1/
I am a fan of RF and LC, but I play a lot of slide and so the sound I’m heading for is more like Lowell George / David Lindley / Rick Veto. I know the 70’ models can sound pretty sharp – on the other hand RF often sounds to compressed and fat for my taste. I think I should still use the Hybrid A schematic to start with, but which values would you recommend ?

2/
I like the idea of beeing able to adjust the OD charakter with a small tone stack like the HRM. Is there a way to add a small tone stack to the Hybrid A schematic, maybe a single ‘tone’ pot ?

3/
I’m a little bit confused because the mounting holes for the chassis are not drilled symmetrically in the top (all more towards the front side), so if the screw-holes in the chassis were symmetrical, the chassis was probably only 200 mm deep. Can that be right ? The cabs inside dimensions are (WxDxH) 585 x 270 x 180 mm. Does anyone know the original sizes of the ODR chassis ?

4/
If I substitute the reverb circuit with a build-in dumblelator loop, I could use the ODR’s send/return pots for that loop and the amp would still look like an ODR. Anyone ever tried something like this ? Anything special to care for ?
BTW - what is a ‘reverb send’ pot good for ?

5/
I know the 70’s ODR /ODS don’t have a master pot. AFAIK in the clean mode there is minimum or no power tube distortion in this kind of amp, even with the CL master on max. volume, right ? What is then the benefit of havin a CL master pot ?
Where would you place an inside trimmer pot for master volume ?

6/
Has anyone ever tried DC tube heating, at least for the preamp tubes ? Is there an audible difference ?

7/
In my ‘carrer’ as a professional electronic technician I built hundreds of PCB-boards by hand and maybe that is why I feel a little ‘uncomfortable’ with them eyelet boards. Is there at least one person who uses PCB boards in his clone with good results ?

8/
Even though some folks might think I’m perverse, I want the amp to look as much as possible like the original (silverface, red slide switches). Does anyone know the font-types Alex used ? Is the labelling of the original 70’ ODS silkscreened ? Does anyone know an anternative that will not look cheap ?

9/
What kind of wire do you use and where do you buy it ?
Is mouser the only company in the universe that sells RN65’s ???
Can’t believe it.

Thanx !

J

[groovtubin]

Hi everybody !

This is my first writing here, but before I start I’d like to tell you that I’m really blown away by so much enthusiasm and superb craftsmanship I found here on this forum.
(Please excuse my humble English, I’m from Germany and havn’t had much English practice since some years). I urgently need some adwise for my Dumble clone project, so here’s my story:

I own an old hardwood top and a 2x12 speaker enclosure from ‘79 or so (mahagony + wicker cane). Until ’82 the top contained an original Dumble ODR. Below is a (cheap) picture of that set.

Unfortunately the amp is gone, I only own the empty top and the speaker enclosure, loaded with only one Altec. (You wanna know what happened to the amp ? I can later post it if someone is interested). Anyhow …I can hear the empty top screaming for tube heat - so I want to bring some life back into it.
I already collected as much information as I could (mostly) from this fantastic forum, bought some parts, made some drawings, but there are still a lot of questions left. It would be great if you could give me some advise.

1/
I am a fan of RF and LC, but I play a lot of slide and so the sound I’m heading for is more like Lowell George / David Lindley / Rick Veto. I know the 70’ models can sound pretty sharp – on the other hand RF often sounds to compressed and fat for my taste. I think I should still use the Hybrid A schematic to start with, but which values would you recommend ?

2/
I like the idea of beeing able to adjust the OD charakter with a small tone stack like the HRM. Is there a way to add a small tone stack to the Hybrid A schematic, maybe a single ‘tone’ pot ?

3/
I’m a little bit confused because the mounting holes for the chassis are not drilled symmetrically in the top (all more towards the front side), so if the screw-holes in the chassis were symmetrical, the chassis was probably only 200 mm deep. Can that be right ? The cabs inside dimensions are (WxDxH) 585 x 270 x 180 mm. Does anyone know the original sizes of the ODR chassis ?

4/
If I substitute the reverb circuit with a build-in dumblelator loop, I could use the ODR’s send/return pots for that loop and the amp would still look like an ODR. Anyone ever tried something like this ? Anything special to care for ?
BTW - what is a ‘reverb send’ pot good for ?

5/
I know the 70’s ODR /ODS don’t have a master pot. AFAIK in the clean mode there is minimum or no power tube distortion in this kind of amp, even with the CL master on max. volume, right ? What is then the benefit of havin a CL master pot ?
Where would you place an inside trimmer pot for master volume ?

6/
Has anyone ever tried DC tube heating, at least for the preamp tubes ? Is there an audible difference ?

7/
In my ‘carrer’ as a professional electronic technician I built hundreds of PCB-boards by hand and maybe that is why I feel a little ‘uncomfortable’ with them eyelet boards. Is there at least one person who uses PCB boards in his clone with good results ?

8/
Even though some folks might think I’m perverse, I want the amp to look as much as possible like the original (silverface, red slide switches). Does anyone know the font-types Alex used ? Is the labelling of the original 70’ ODS silkscreened ? Does anyone know an anternative that will not look cheap ?

9/
What kind of wire do you use and where do you buy it ?
Is mouser the only company in the universe that sells RN65’s ???
Can’t believe it.

Thanx !

J

what happened to the amp??????:)

[groovtubin]

Hi everybody !

This is my first writing here, but before I start I’d like to tell you that I’m really blown away by so much enthusiasm and superb craftsmanship I found here on this forum.
(Please excuse my humble English, I’m from Germany and havn’t had much English practice since some years). I urgently need some adwise for my Dumble clone project, so here’s my story:

I own an old hardwood top and a 2x12 speaker enclosure from ‘79 or so (mahagony + wicker cane). Until ’82 the top contained an original Dumble ODR. Below is a (cheap) picture of that set.

Unfortunately the amp is gone, I only own the empty top and the speaker enclosure, loaded with only one Altec. (You wanna know what happened to the amp ? I can later post it if someone is interested). Anyhow …I can hear the empty top screaming for tube heat - so I want to bring some life back into it.
I already collected as much information as I could (mostly) from this fantastic forum, bought some parts, made some drawings, but there are still a lot of questions left. It would be great if you could give me some advise.

1/
I am a fan of RF and LC, but I play a lot of slide and so the sound I’m heading for is more like Lowell George / David Lindley / Rick Veto. I know the 70’ models can sound pretty sharp – on the other hand RF often sounds to compressed and fat for my taste. I think I should still use the Hybrid A schematic to start with, but which values would you recommend ?

2/
I like the idea of beeing able to adjust the OD charakter with a small tone stack like the HRM. Is there a way to add a small tone stack to the Hybrid A schematic, maybe a single ‘tone’ pot ?

3/
I’m a little bit confused because the mounting holes for the chassis are not drilled symmetrically in the top (all more towards the front side), so if the screw-holes in the chassis were symmetrical, the chassis was probably only 200 mm deep. Can that be right ? The cabs inside dimensions are (WxDxH) 585 x 270 x 180 mm. Does anyone know the original sizes of the ODR chassis ?

4/
If I substitute the reverb circuit with a build-in dumblelator loop, I could use the ODR’s send/return pots for that loop and the amp would still look like an ODR. Anyone ever tried something like this ? Anything special to care for ?
BTW - what is a ‘reverb send’ pot good for ?

5/
I know the 70’s ODR /ODS don’t have a master pot. AFAIK in the clean mode there is minimum or no power tube distortion in this kind of amp, even with the CL master on max. volume, right ? What is then the benefit of havin a CL master pot ?
Where would you place an inside trimmer pot for master volume ?

6/
Has anyone ever tried DC tube heating, at least for the preamp tubes ? Is there an audible difference ?

7/
In my ‘carrer’ as a professional electronic technician I built hundreds of PCB-boards by hand and maybe that is why I feel a little ‘uncomfortable’ with them eyelet boards. Is there at least one person who uses PCB boards in his clone with good results ?

8/
Even though some folks might think I’m perverse, I want the amp to look as much as possible like the original (silverface, red slide switches). Does anyone know the font-types Alex used ? Is the labelling of the original 70’ ODS silkscreened ? Does anyone know an anternative that will not look cheap ?

9/
What kind of wire do you use and where do you buy it ?
Is mouser the only company in the universe that sells RN65’s ???
Can’t believe it.

Thanx !

J

what happened to the amp??????:)

[Bob-I]

Hi everybody !

This is my first writing here, but before I start I’d like to tell you that I’m really blown away by so much enthusiasm and superb craftsmanship I found here on this forum.
(Please excuse my humble English, I’m from Germany and havn’t had much English practice since some years). I urgently need some adwise for my Dumble clone project, so here’s my story:

Welcome, your English is as good as anyone's here.

1/
I am a fan of RF and LC, but I play a lot of slide and so the sound I’m heading for is more like Lowell George / David Lindley / Rick Veto. I know the 70’ models can sound pretty sharp – on the other hand RF often sounds to compressed and fat for my taste. I think I should still use the Hybrid A schematic to start with, but which values would you recommend ?

I'd start with the values shown on the OSD101 posted by HiGain on the files forum. He compiled these with lot sof input from this forum.

2/
I like the idea of beeing able to adjust the OD charakter with a small tone stack like the HRM. Is there a way to add a small tone stack to the Hybrid A schematic, maybe a single ‘tone’ pot ?

I used a single pot on one of my Hybrids. I used a single cap and pot to cut some of the shrill highs. It gives a fairly wide range of tone. I'll have to open the amp to find the final values but I believe it's a 250K pot and a .022uF cap.

3/

4/

Sorry, I can't answer these.

5/
I know the 70’s ODR /ODS don’t have a master pot. AFAIK in the clean mode there is minimum or no power tube distortion in this kind of amp, even with the CL master on max. volume, right ? What is then the benefit of havin a CL master pot ?
Where would you place an inside trimmer pot for master volume ?

Not exactly. There is a master volume pot just before the phase invertor, plus a "ratio" pot that controls only the OD volume. With some juggling you can get the OD volume and the clean volume set. No there's no power tube distortion on these amps, strictly preamp distortion.

6/
Has anyone ever tried DC tube heating, at least for the preamp tubes ? Is there an audible difference ?

No, in fact the heaters are very quiet. I'd almost expect that the diode noise could be worse.

7/
In my ‘carrer’ as a professional electronic technician I built hundreds of PCB-boards by hand and maybe that is why I feel a little ‘uncomfortable’ with them eyelet boards. Is there at least one person who uses PCB boards in his clone with good results ?

I know that Fuchs makes PCB Dumble like amps very successfully. I for one would love to see you make PCB's, in fact I'd buy some from you!!

8/

Sorry, I can't answer this one.

9/
What kind of wire do you use and where do you buy it ?
Is mouser the only company in the universe that sells RN65’s ???
Can’t believe it.

I like the PTFE (teflon) coated wire from Apex Jr, 20AWG stranded, and the 20AWG shielded PTFE wire also from Apex. http://apexjr.com/

I've bought RN65's from Mouser and Allied http://www.alliedelec.com/default.asp

Thanx !

J

You're welcome. Now let's see those PCB's. I think that would be awesome.

[jelle]

Hi,

Maybe it is possible to get an chassis looking just like the one in the picture! I have seen pics of an ODS reverb chassis from natchakom@hotmail.com looking very similar but with five preamptubes instead of six.

From what I understand, the dumbleator adds it's own flavour to the sound....the ODRS's reverb section is very neutral sounding.

Please tell us what became of the amp itself...I hope no one modified it to an high gain amp or anything?

What type of altec is in the cab?

Thanks,
Jelle
The Netherlands
jwelagen (at) hotmail.com

[Runaway J]

Bob, Jelle

thank you for your help, makes things much easier for me.
I’ll do my best to finish the pcb-layouts and post it here. Unfortunately I’m not familiar with VISIO, all my drawings are in AUTOCAD, but I could convert them to pdf.

For those who want to know what happened to the amp, here’s the story from A to Z:
The first owner of the amp was my brother. It was a 50 watt ODR top and a 2x12 loaded with Altecs 417 8H SII (BTW the best guitar speaker ever built IMO). He ordered it I think in ’79 from a shop in Bochum, Germany, called ‘Applied Acoustics’, the company which later became ‘Kitty Hawk’ and built the first commercial dumble clone, the ‘Kitty Hawk Standard’ (anyone got a schematic?). It was one of the 25 or so amps that HAD shipped to Germany, maybe the only top with reverb. He had to pay the total amount in advance and for more than 6 month he didn’t hear nothing from AA, no telephone contact possible, nothing at all. He had nearly given up his money when suddenly the amp arrived at our door. I didn’t know much about electric guitar playing then, but this thing really impressed me. It sounded awesome, never heard anything like that before.

He used the amp with his local band for about 2 years. During that time the wicker cane was damaged and replaced with an ugly brown clothing. In 82 the band finally split up and the amp was only used for practicing. The amp sounded great as I said, but using it for playing at home was nearly impossible, ‘cause it had to be pushed a bit to get THE sound, but then it was LOUD as hell. So he let the amp chassis and one of the Altecs build in a smaller cab in “road ready” design (greenish glazed wood, steel edges, etc.), just to tame it a bit and make it easier to handle. Then, I think in 83, he sold that amp (for about 800 $) because he focussed on acoustic guitar playing and needed money for a new guitar (… you know my favorite topic when I want to ruin his day ?). The guy who bought it moved to Munich, and that is where the trace is lost. Has anyone ever seen this amp again ?
The old hardwood cases and one Altec stayed here. Brother tells me that he was never really happy with the amp. It’s hard for him to explain, but he tells that somehow the amp was simply to mighty for him or for his style of playing. I guess it was the touch sensitivity and the sheer sound level that made it difficult to use for him.
In ‘85 or ‘86 I bought the cases and the Altec from him (I paid with my old headphones) because I was training to become an electronic technician (and guitar player) and I thought I could use them for a new build, but neither could I get schematics nor parts and so the cabs became pieces of furniture. Hope that period will be over soon.

Thanx for your interest.

Cheers

J

[Funkalicousgroove]

If you like Lowell George/David Lindley tones I'd use the standard Fender Plate/cathode values (100K over 1K5), use 25uf bypass caps on V1 and 5uf bypass caps on v2, you can experiment with the values of mid cap, but for slide I really like .02uf.

My personal opinion on reverb:

Built in spring reverb is a TONE LEACH PERIOD, build an amp, use an external reverb if you MUST have verb, it's best added after the speaker though.

I also feel STRONGLY that the loop device should be separate, and on a separate power supply, it's very simple to build.

that's my $.02

[jelle]

Hi RJ,

Thanks for the story/info. Bochum must be something special then.... I bought my L series strat at Beyer's Music! It is just about one hours drive I guess...

In the files section there is a schem of the preamp of an ODRS drawn by Ben Shelton.
I have tried this schem in a Super reverb and it is a good blues circuit...at least for me...but pretty LOUD. Also the Rock mode is too much for me in this schem....

The more modern schematics are easier to use at lower volumes, are more evolved and sound great. I totally agree with Funk on the 100k plates for those sounds...and they are great sounds......Robben Ford/Santana like sounds would be the 220k to 120k plate resistors seen on most schems at this forum.

I hope this helps

Jelle

[Bob-I]

Bob, Jelle

thank you for your help, makes things much easier for me.
I’ll do my best to finish the pcb-layouts and post it here. Unfortunately I’m not familiar with VISIO, all my drawings are in AUTOCAD, but I could convert them to pdf.

Of course that's fine. Even better would be complete boards etched by someone experienced in etching PCB's. I've never done it.

[Bob-I]

Oh, and I don't disagree on the Altec speakers, but in my experience it's the speakers, not that amp that need to be cranked to get "THAT" sound. I had a pair of Altec's in a modded Twin in the 70's and cranked it sounded amazing. I swapped them for EVM speakers and was able to get a great sound at far lower volumes. I'll admit they never sounded as gutsy as the Altec's at any volume, but they sounded 100% better at reasonable volumes.

just my $.02

[Runaway J]

Some years ago I A/B/C’d the Altec with an EVM12L and a Celestion V30 in an open back cabinet. If I remember it right (no guaranty) the Altec and the EV sounded very much the same at low volumes. Cranked up the Altec had richer harmonics. So I agree to the tendency.
Bob, did you have the same type like me, 417 8H Series II ?
The V30 was really getting on my nervs after 5 min. of playing ‘cause of its extreme midrange peak. Maybe the V30 fits better in a closed cab.
Anyone ever tried Weber’s California 12 Ceramic ? I read somewhere that this speaker soundwise is between the Altec and JBL’s D120 (I think Ry Cooder uses JBL’s).
Could be nice sounding with an ODS clone.

Thanks everyone for the input.

(not my speaker on the pic's, but just the same)

[Bob-I]

Some years ago I A/B/C’d the Altec with an EVM12L and a Celestion V30 in an open back cabinet. If I remember it right (no guaranty) the Altec and the EV sounded very much the same at low volumes. Cranked up the Altec had richer harmonics. So I agree to the tendency.
Bob, did you have the same type like me, 417 8H Series II ?

Yes, same type. I never should/ve sold them.

The V30 was really getting on my nervs after 5 min. of playing ‘cause of its extreme midrange peak. Maybe the V30 fits better in a closed cab.

Yep, annoying.

Anyone ever tried Weber’s California 12 Ceramic ? I read somewhere that this speaker soundwise is between the Altec and JBL’s D120 (I think Ry Cooder uses JBL’s).
Could be nice sounding with an ODS clone.

Thanks everyone for the input.

I've tried an old JBL D-120 and it sounds great. Excellent speaker for these amps. The downside of the JBL is that they don't like extreme volumes overdriven. IME they can handle almost anything clean but with an overdriven amp they tend to get volice coil rubs. Since I seldom play loud it's not an issue for me.

Can't quote on the Weber.

[hipbluescat]

Concerning the altec speakers I would recommend changing the cone to card board. When distortions happens this gets rid of harshness in the tone.

Regards

[philmanatee]

I haven't messed with a dumble style amp yet, still waiting on my d'lite kit. I am currently using an altec 417 just like the one pictured in tandem with a celestion blue alnico.I power these with my express clone and trem-rocket and this is my favorite combination of two 12's for this amp setup. I think getting rid of the aluminum dustcap and replacing it with a paper one is the way to go for distorted tones on the altec. I use a 12 inch weber california in my magnatone 440 and it is a different animal than an altec, but mine is the ceramic magnet so it's hard to compare to the altec's alnico. The california is a great speaker, I mostly use it for clean sounds but it is very huge sounding. Phil