Hybrid 3rd-4th Gen Non-HRM Low Plate...

[Paul-in-KC]

All,

Not sure if this will be of any interest or use to others, but here are the documents that I have created in the process of creating my 3rd-4th Gen Hybrid that I just finished.

These may contain errors, but I believe they accurately reflect the amp that I built - as I built it.

It's mostly the "Generic 3rd Gen Period Correct ODS 50W" that Tony Albany has documented. I simply added a OD Volume and Presence control to match the chassis that I was building in (from Amplified Nation). There are some other deviations from Tony's drawing. Those are accommodations for component availability or adjustments necessary for proper function. Notably, the 3.3K resistor in the bias circuit (prior to the diode) had to be lowered to a 1.8K in order to have enough negative voltage in order to provide a workable range of bias voltage.

Here is the schematic and a layout (of sorts) of the main circuit board. I would also like to create a layout, but not sure if/when I will get to it.

ODS50W-3rd-4th-hybrid.pdf

ODS50W-3rd-4th-hybrid_main_board_layout.pdf

Thanks to all of the forum members that contributed to this.

Feedback on credits, errors, etc. is welcome and appreciated.

I don't have any other D-style experience to compare with, but I really like the sound of this amp so far.

-Paul

[Paul-in-KC]

BTW - the main board layout is to scale.

I used it as my template to drill the main eyelet board. HOWEVER the mounting holes (in the 4 corners) are not to any scale - or particular location. So - you would want to make those to match your hardware and chassis (or the other way around - of course).

-Paul.

[Paul-in-KC]

All,

Another thing I just noticed looking at the Period Correct 3rd Gen layout from Tony (again) is that I completed the passive loop with a return jack.

I also should have credited Mark Roberts (mdroberts1243) with creating the original schematic to accompany Tony's layout.

-Paul

[M Fowler]

Always great to have more reference data for our builds thanks. Enjoy your amp.

Mark

[Charlie Wilson]

I am curious. What is "Low Plate Classic" about this amp? It looks like a 3rd generation with a OD master and presence. A classic tone stack is 330pf(treble), .047(mid) and .1(bass).
CW

[Paul-in-KC]

I am curious. What is "Low Plate Classic" about this amp? It looks like a 3rd generation with a OD master and presence. A classic tone stack is 330pf(treble), .047(mid) and .1(bass).
CW

Great Question Charlie - and one of those corrections that I was asking for!

I was following the "Generic 3rd Gen Period Correct ODS 50W thread for the base circuit. I'm not sure where I picked-up/added the "classic" part in the description. No telling now - and I definitely don't have the experience in D-style to catch that. I also see that the added volume control is in the OD, not the Master as you also point out.

My apologies for the erroneous "classic" (and volume control) attribution.

Thanks for pointing those out.

-P.