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#1
If you dont know about Dumble amplifiers then here ya go. . Basically they are limited production amps (less than 300 ever made since the 70s) and expensive now a days, $35,000.

Anyways I am building a 50W ODS (Over Drive Special). It's an 80's version and based on the highly documented #124, that was degooped and rev engineered. #124 was a ODS in it's prime. The amp has two 6L6 in fixed bias for its output.

There are two inputs: a "normal" input and FET input where the signal from the guitar goes to a J-FET line level booster pre-amplifier before entering the first tube stage (originally intended for use with acoustic guitars and other instruments with low output levels).

The first tube is followed by a passive tonestack with adjustments for treble, middle, and bass. Typical switching options available in the different models include:

Bright (bypasses the volume potentiometer with a capacitor to boost the high frequencies)
Deep (changes the voicing of the tonestack for a warmer tone)
Mid (increases the value of the treble capacitor to boost the midrange frequencies)
Boost (disconnects the treble potentiometer from the bass potentiometer for a preamplifier level boost)
Rock/Jazz (switches between a Fender-esque voicing and a more "hi-fi-type" of voicing).
The tonestack is followed by another clean preamplifier stage. The resulting signal is either fed straight into the power amplifier ( clean channel), or into the (two-stage) overdrive section. The power amplifier uses a standard long-tail pair phase inverter with negative feedback. It will break up , but only at very high volume levels, or when the preamplifier "boost" switch is engaged.

The "Skyliner" EQ refers to a newer (mid-1980s to present) way of voicing the tonestack. It is said to provide a better clean tone than the earlier voicing of the tonestack. Some lower serial number amps have been retrofitted with this EQ.


Not sure when I am going to finish this build as I have been very busy these days. Also dont have the transformers or cab, and dont know when I can buy those. Going to university in September so it will most likely be a long term build.

Should be a fun build. It is quite big and fairly complex so I wont blow through it. I also dont have a layout to follow really. I am using two layouts and kind of blending them together. I am doing this because I am doing a 50W build and the PSU board I have is a bit different.

Got the chassis today. It's an exact replica of an 80's ODS.





Got a bunch of tubes to try in this build...


Here are the parts I have as of now...


Waiting on a Mouser order to come in now before I can get started. Going to do some chassis work on it now though.
#2
1 - Take your time. This is an extremely complicated amp and things will get cluttered very fast.
2 - High gain amps require special attention.
3 - Lead dress is critical. Learn everything you can from whatever gutshots you can find.
4 - Grounding paths are critical. Learn everything you can from whatever gutshots you can find.
5 - Take your time. This is an extremely complicated amp and things will get cluttered very fast.
Meadows
Quote by Jackal58
I release my inner liberal every morning when I take a shit.
Quote by SK8RDUDE411
I wont be like those jerks who dedicate their beliefs to logic and reaosn.
#3
I wouldn't consider this amp high gain but anyways...I have been studying everything about these amps so I am pretty confident. They are very sensitive to lead dress and very hard to tweak to get just right.

I have a layout that shows lead dress and grounding. After my DR I feel quite confident on grounding. SYK if you want PM me and I will send you my layouts and the tons of photos I have of #124.
#4
kurtlives91, one day, i want to grow up to be you.


i wish i knew where to even begin on a project like this, i guess i'll stick with my pedal mods for now.
Official Aspie member

ANOUNCEMENT: Weird misspellings or words that make no sense? there was a good chance this was sent from my Droid 2 phone.
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#5
Quote by conor1148
kurtlives91, one day, i want to grow up to be you.


i wish i knew where to even begin on a project like this, i guess i'll stick with my pedal mods for now.
A couple years ago Chris was just doing pedal stuff...
Meadows
Quote by Jackal58
I release my inner liberal every morning when I take a shit.
Quote by SK8RDUDE411
I wont be like those jerks who dedicate their beliefs to logic and reaosn.
#6
Quote by SomeoneYouKnew
A couple years ago Chris was just doing pedal stuff...



a couple of decades ago so were you then :P


as you appear to be master of all electronics knowledge
Quote by Deliriumbassist
Antisocial Behaviour Order. A chav's equivalent of GCSEs.
#7
I'm going to be following this thread with considerable interest. I've seen the various photos, layouts and schematics for this amp, but am not sure if I need the complexity. I'd like to build a single channel amp with huge clean headroom, but this one would do the trick too in a pinch.

Please keep the updates coming as you progress!
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#8
Quote by rancidryan
a couple of decades ago so were you then :P


as you appear to be master of all electronics knowledge
Decades? I didn't start when I was two.
Meadows
Quote by Jackal58
I release my inner liberal every morning when I take a shit.
Quote by SK8RDUDE411
I wont be like those jerks who dedicate their beliefs to logic and reaosn.
#9
Quote by Vulcan
I'm going to be following this thread with considerable interest. I've seen the various photos, layouts and schematics for this amp, but am not sure if I need the complexity. I'd like to build a single channel amp with huge clean headroom, but this one would do the trick too in a pinch.

Please keep the updates coming as you progress!

Will update as I progress.

For max headroom a 100W ODS or a Steel String Slinger might be better. SRV used both.


Just for the record two and a half years ago I was struggling with the most basic pedals. Now I am building Dumbles and shi tz. I was 15 when I started now I am 17. I have found something I enjoy and I am running with it. Led me to something to do in university, first year elec eng in September!
Last edited by kurtlives91 at Jul 17, 2009,
#10
Stickying this
Then there's this band called Slice The Cake...

Bunch of faggots putting random riffs together and calling it "progressive" deathcore.
Stupid name.
Probably picked "for teh lulz"

Mod in UG's Official Gain Whores
#11
Stuck.

Looks cool, Chris.
Current Gear:
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You CAN play anything with anything....but some guitars sound right for some things, and not for others. Single coils sound retarded for metal, though those who are apeshit about harpsichord probably beg to differ.
#12
SHOOMAMA! man those amps sound awesome! and all nice components too.
Founding Member and President of UG Geezer Guild
#13
Wow, that's a lotta t00bz.
This looks very interesting.
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#15
Quote by BD 425
Wow, that's a lotta t00bz.
This looks very interesting.

I know! I wish I had a selection of tubes like that
Then there's this band called Slice The Cake...

Bunch of faggots putting random riffs together and calling it "progressive" deathcore.
Stupid name.
Probably picked "for teh lulz"

Mod in UG's Official Gain Whores
#16
Quote by Shinozoku
I know! I wish I had a selection of tubes like that
the plain white boxes draw most of my interest. and the sylvania...
Meadows
Quote by Jackal58
I release my inner liberal every morning when I take a shit.
Quote by SK8RDUDE411
I wont be like those jerks who dedicate their beliefs to logic and reaosn.
#17
Me too actually, and the TADs
Then there's this band called Slice The Cake...

Bunch of faggots putting random riffs together and calling it "progressive" deathcore.
Stupid name.
Probably picked "for teh lulz"

Mod in UG's Official Gain Whores
#18
Quote by SomeoneYouKnew
the plain white boxes draw most of my interest. and the sylvania...

White boxes are NOS tubes. Mostly JAN Phillips, GE, RCA and a few Conn.

No progress yet, need to get five pedals finished this weekend.
Last edited by kurtlives91 at Jul 18, 2009,
#19
Quote by kurtlives91
White boxes are NOS tubes. Mostly JAN Phillips, GE, RCA and a few Conn.
Yes, I know.
Meadows
Quote by Jackal58
I release my inner liberal every morning when I take a shit.
Quote by SK8RDUDE411
I wont be like those jerks who dedicate their beliefs to logic and reaosn.
#21
I know what to look for.


I'm curious about the chassis. Who makes those. Aren't there copyright/trademark issues?
Meadows
Quote by Jackal58
I release my inner liberal every morning when I take a shit.
Quote by SK8RDUDE411
I wont be like those jerks who dedicate their beliefs to logic and reaosn.
#22
stuck. I know bugger all about electronics would have listened more about it in school if i wasnt colour blind and could get a job in this feild, i might take it up for a hobby when i finaly get a job.
-goodluck
Without music, life would be a mistake.
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I love you for that thread...


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#23
Quote by SomeoneYouKnew
I know what to look for.


I'm curious about the chassis. Who makes those. Aren't there copyright/trademark issues?

It's from this guy in Thailand. Very good quality and an exact replica of the real deal. Huge trademark issues, so un legit, if HAD he would flip.

Got a question about the PT...
I want 440V on the 6L6 plate's. How do I figure out what secondary HT voltage I want? I figure I need quintescent current and some load line plotting? I am not sure how much the B+ will drop under load...
#24
Quote by kurtlives91
It's from this guy in Thailand. Very good quality and an exact replica of the real deal. Huge trademark issues, so un legit, if HAD he would flip.


lol

Quote by kurtlives91
Got a question about the PT...
I want 440V on the 6L6 plate's. How do I figure out what secondary HT voltage I want? I figure I need quintescent current and some load line plotting? I am not sure how much the B+ will drop under load...
ugh. this is always a big pain in the ass when designing an amp. worse when there's a tube rectifier involved. you're using solid state, right? two or three ss diode in series on each leg of the transformer? 2volts drop there, so you can basically throw them out of your calculations.

the "right" way to do this would be to start with your 440v and work backward.
ADD to the 440v, the voltage dropped across the rectifiers AND add the voltage dropped across the series resistance of the transformer.
calculate the idle current, and any other paths for dc, like voltage dividers, bleeder/equalizing resistors, etc. multiply that times the series resistance to get the voltage dropped. Add these two voltages to the 440v.
then divide that number by 1.414.

This gives you a pretty good estimate of what the AC voltage on your secondary should be.

Are we done yet?
Nope!

Something we didn't take into consideration: How close is your local line voltage to the voltage your transformer manufacturer uses when specs its voltages. It's very common to be +/- 5% from that standard. Will this cause you problems? Do you need to recalculate?

In your case, I think there's little danger of going over-voltage.
440v is pretty conservative for 6L6 plates.
iirc, that's what a blackface BandMaster uses.
being the lazy bastard that I am, I'd probably just steal the numbers from Fender.
They used a 320-0-320vac secondary.
I'd probably just do that, and be happy.
Meadows
Quote by Jackal58
I release my inner liberal every morning when I take a shit.
Quote by SK8RDUDE411
I wont be like those jerks who dedicate their beliefs to logic and reaosn.
#25
Yeah, breakin the law, fu ck yes I'm a badass!

Ya SSS recto, three diodes in series. One 1N4007 would be sufficient but o well. Negligible voltage drop there.

Thanks for the advice. For 50W builds Bassman transformers are usually used. The ones I were looking at were putting out B+ of just under 500V though. I actually was thinking of using a Bandmaster. I was stuck between 320V, 325V and 330V secondaries though. Probably going to go with the one with the bigger filament current and B+ handling.
#26
Did a bit of chassis work. Was kind of over whelming at the start, had so much drilling and such to do. Almost everything is mounted, just a few things left...Still need to mount relay boards, grounds and a few little more things.

Got my Mouser order in so I basically have everything I need. Still waiting on an order for wire, socket covers, OT, pots and a few other random things. Once I have the wire I can start really building.

Forgot to post pics of these before. These are the choke and footswitch I got.



Progress pics...



#27
Oh man, this is getting good! Nice work!
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Unless its electronic drums.

BURN THE WITCH!!!!!
#28
This is going to be awesome. Looks really good so far, I hope to reach this sort of level in building one day.

Back to practicing =)
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#29
Did a bit of work a while back, then went away for a while. Came back yesterday and got a bit more work done today. So far I have done all chassis work. Well actually I need to grind the chassis under all the 1/4" jacks but o well. All hardware fits and there is no problems! Mounted and tightened all the back hardware but not the front yet. Still missing an 18mm 250K(A) pot!!!

Also started work on the PSU and main board eyelet. Still not total complete on either of them. Still have to do more research and figure a few things out. Also wired the heaters, did them in the true HAD ODS style.

O also got a 50W Bassman OT, it has 4R, 8R and 16R taps.


Bias jacks added. All nuts tightened like the real #124 I know





Note how the heaters go vertical almost immediately, that's how the original ODS did them.




Wire color coding same as real #124. Really like this solid core teflon wire.
#30
Quote by kurtlives91
Bias jacks added.
All tube amps should have these.

Quote by kurtlives91
Really like this solid core teflon wire.
Dunno about the teflon part but otherwise, Ken would approve.
Meadows
Quote by Jackal58
I release my inner liberal every morning when I take a shit.
Quote by SK8RDUDE411
I wont be like those jerks who dedicate their beliefs to logic and reaosn.
#31
HOLY ****

I was up most of night yesterday looking up these Dumble amps and the Ceriatone kits modeling them and now here it is. Defiantly following. Looking good so far.
"Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo."
#32
This is going to be a great amp. It is such a clean looking build. I wish I could figure out how to get a nice finish on a chassis like that.

I love the way you did the heaters. I'm not a fan of solid core wire, but to each his own.

What's the second and third button on the footswitch do?
#34
Quote by guitarcam123
he bought the chassis. And its most likely powder coated?


I'm aware of this, but someone still had to make it. I'm also talking about the script on it. I've been looking everywhere for small stencils, but can't find them so I've resorted to finding someone with excellent handwriting to mark the controls on my amps.
#35
SYK I totally agree with you on bias jacks. Such a simple little add on that makes maintaining your amp that much easier.

end_citizen thanks for the comments first.

The footswitch has three buttons. Typically ODS only use a two button footswitch, many are modded for the third footswitch though.
1. Overdrive, turns the overdrive on or off.
2. PAB (Pre Amp Boost), disables the tonestack and gives you a gain/solo boost. It is nothing like taking away the tonestack in a Fender.

3. The third footswitch usually controls the Mid Boost. This requires adding another relay and some extra circuitry but I may do it.
#36
Quote by SomeoneYouKnew

Dunno about the teflon part but otherwise, Ken would approve.

Just realised I said telfon. I mean PVC, real ODS' used PVC.

Teflon is a bit ch to strip.
#38
I was getting into pedal building lately.

I can pretty much build most of the stuff i want. But a week ago i thought about amp building.
I started reading some articles.

After a few pages of stuff about sexy NOS parts, huge transformers, tubes and stuff there were writings about the importance of wiring and stuff. I was amazed and shocked simultaneously.

What i got out of the article was something like most of the wirings, cable lenghts, ground points can give you noise and it is only luck if you can get it right or something like that. It sounded like vodoo magic too me.

So my biggest respect to you.
01110111001101101
10101101000
0110010
0101
01
0
******A Console Cowboy****** 1
01
0101
0110010
10101101000
01110111001101101
#39
Quote by Daneeka
What i got out of the article was something like most of the wirings, cable lenghts, ground points can give you noise and it is only luck if you can get it right or something like that. It sounded like vodoo magic too me.
Oh, goodness no.
It might seem like that, but it's just a matter of understanding the basic principles of proper lead dress and grounding techniques. Chris had a few issues with his Vibro Champ build. With a little guidance from me and lot of research on his part, he was able to clean it up nicely. His Deluxe Reverb build went very smoothly.

Not voodoo. Knowledge. Patience. Attention to detail.

Quote by Daneeka
So my biggest respect to you.
Agreed. He's been doing some beautiful work, recently.
Meadows
Quote by Jackal58
I release my inner liberal every morning when I take a shit.
Quote by SK8RDUDE411
I wont be like those jerks who dedicate their beliefs to logic and reaosn.
#40
Quote by kurtlives91
Just realised I said telfon. I mean PVC, real ODS' used PVC.

Teflon is a bit ch to strip.


Thats quite interesting you say that about Teflon. I find it easier to strip teflon wiring, but many people like the heated wire strippers and that would not work on it.
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