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[WhopperPlate]

Hello everyone,

Long time no post! After a long hiatus away from amp building I am contemplating an ODS. After starting and nearly completing a Marshall 1987 amp, it has been so much fun that I have decided to complete the ODS I once started. A friend of mine who once owned several dumbles has also lit a fire under me to possibly build a replica of his old amp.

Have a couple points of curiosity I was hoping I could be educated about:

1) what is the overall concensus on the sonic differences between the precision and standard power supply circuits?

2) where is a recommendable source for boards and chassis besides ceriatone?

3) my friends amp was a 100 watt ODS 112 combo with tremolo, can't remember if it had reverb. What is the general circuitry history for this era of amplifier?

Thank you all for this lovely forum and the priveledge to learn so much!

Charlie

[martin manning]

1) what is the overall concensus on the sonic differences between the precision and standard power supply circuits?

Since they are the same basic circuit, I think this will depend more on the values of the capacitors used. The reservoir seems to vary between 110 and 160uF in both types, and this may have been selected for the original purchaser.

2) where is a recommendable source for boards and chassis besides ceriatone?

CE Pedals is the best source for chassis http://cepedals.com/Dumble-Style-Chassis.html , and J Borders http://www.agbamplifiers.com
for matching board sets. Both of these sources have had varying availability. Members list these items in the for sale area here from time to time.

3) my friends amp was a 100 watt ODS 112 combo with tremolo, can't remember if it had reverb. What is the general circuitry history for this era of amplifier?

Check the files section for the evolution of the ODS circuit.

[WhopperPlate]

Thank you Martin!

Thank you for the links, I will be ordering very soon!

I managed to find the Rob Livesey page which helped me a lot. Seems like the one my friend is referring is either a 2nd or 3rd gen.

http://www.thesubjectmatter.com/dumblearchive.html

I am just gonna leave that here.

Again very much appreciated! Thank you!

Charlie

[dorrisant]

Check here:

http://ampgarage.com/forum/viewtopic.php?t=29462

Dave still has two for sale that seem to be a great deal!

[WhopperPlate]

man, hard to choose. Love the 2nd and 3rd gen clean light breakup tones, but dig those 4th and 5th gen OD sounds for sure. Seems like the early models favored cleans over the later models with OD, is this an accurate statement?

That Doug Doppler clip, it's a classic low plate converted to Hugh plate skyline with no HRM 4th gen, or something like that right?

The internal dumbleator has also got me held up. Seems like possible extra noise and/or potential interference if not real careful with lead dress. The dumbles I have seen with them look like they have a bunch of extra shielding. Any preference for internal vs external in this regard or sonic tonal characteristics? Seems more versatile external.

Thanks for hearing me out, I am sure these questions are as common as dirt, I appreciate the patience!

Charlie

[JazzGuitarGimp]

With four preamp holes, you could ditch the d-lator and do a dedicated clean preamp with its own tone stack. You'd just need to make sure the front panel is wide enough to acommodate the extra pots. But it would give you the option of using the clean preamp from the early generation and the OD preamp from the later generation.

[WhopperPlate]

That's an idea! Reformatting the front panel seems a bit of challenge considering the referenced chassis control panel silk screening. Definitely got me thinking though.

Charlie

[WhopperPlate]

So, what's the low down on the ratio vs volume for the overdrive channel? His do these work and do either work bette with some circuits then others?

[martin manning]

Depending on which generation of ODS, the OD controls are labeled Level and Ratio, or Drive and Volume. AFAIK the functionality of these controls is the same, with the Level/Drive controlling the signal level into the second stage of the OD section, and the Ratio/Volume controlling the signal level coming out of the second OD stage. The purpose of the Ratio/Volume control is to set the OD volume with respect to the Clean volume for the chosen settings of the input Volume and the Level/Drive controls.

[WhopperPlate]

And I here I thought it was done fancy deviation from the norm, thanks for setting me straight.

Charlie

[norburybrook]

I have a #102 with the ratio and a HRM Blues master with level. Now, as far as I can tell from the way it works they seem different.

I would hesitate to even question Martin as his knowledge in these matters is bordering on genius... but..here's my take.


On my 102 the ratio gives a 'balance' between the clean and overdrive levels. On the BM the level controls acts as a separate master volume for the OD.


This might be what martin is saying but I thought I'd add how it feels very different in use somehow obviously the end result is the same.


I first noticed the difference because both my front panels are the same so have 'ratio' written but I noticed a difference in how the two amps behaved in this respect.


Marcus

[Synchu]

Completely right Marcus, Bkuesmasters drive channel volume design is different from the ODS "line". It indeed sets the overall volume independently from the Master.
I believe Martin is referring to ODSs naming quirks that function the same though.

Niki

[martin manning]

Yes, from the limited sample available HRM amps seem to have separate masters controlling the output from the clean section and the output from the OD section independently. The ratio and global master system and the separate master system are two different ways to accomplish the same thing.

[norburybrook]

Completely right Marcus, Bkuesmasters drive channel volume design is different from the ODS "line". It indeed sets the overall volume independently from the Master.
I believe Martin is referring to ODSs naming quirks that function the same though.

Niki

Ah, I'd forgotten that the level/Ratio thing was also used in the ODS amp range. I'd presumed that the level was indeed the separate master volume.

Just adds to the confusion

The BM is a cracking amplifier , probably the best clean you will get on a Dumble ODS


Marcus