ODS101 schematic

[HiGain]

Guys,

To help myself see things more clearly I made a schematic that aims to be the fundamental starting point according to some contributers here (dogears, Gil, Bob, Norm, Funk, Gary-- et al.-- sorry if i missed some of you)

I don't believe it contains any secrets or things that would offend any one. But, I thought I'd ask if it's OK to post. I'll finish up a few details tonight, and post if there are no objections.

Also, I wanted to ask a question about the boost swtich before posting: Is it supposed to switch in another cap in parallel or series?

Thanks,
Jake

[Funkalicousgroove]

The boost switch is supposed to switch a pair of resistors in series with the middle and ccw leg of the bass control

[Bob-I]

Post away as far as I'm concerned. There's no secrets between us hobbysts, the pros might feel different but not me.

[HiGain]

OK, Here it is.

I have a couple final questions. First, Funk, I meant to ask about the mid-boost. I drew the caps in series. Should they be parallel?

2. Can anyone confirm the PI input cap.

3. Is there a final word on the global feedback string?

Thanks all,
Jake

EDIT: Updated schematic... But, still not yet final verion.

[Bob-I]

Excellent drawing, clean and easy to read. I like the idea a lot.

Only one thing I see from the quick glance I gave this. The HRM mod needs to change the OD master to 1M. Otherwise it looks great.

[Normster]

I'll study this tomorrow, but here are a few observations:
Treble pot is 250k-L
OD1 has 180k plate/2.7k cathode
OD2 has 120k plate/1.8k cathode
Cathode resistors are just regular carbon film. I guess there's no harm in using RN65s, but they're not required.

I don't know about confirming the PI input cap. I typically use .02uF but I've tamed a bassy amp by using .01uF.

Overall, excellent drawing!

[ElectronAvalanche]

Hi,

the Mid-Boost-Switch is definitely wrong.

It should switch out the second series cap (330pF), otherwise you will have B+ on the switch.

Cheers,

Dominik

[swt]

bypass cap on cl2 is suggested to be 10uf, in non hrm, and if the amp gets bassy, a series .047 cap should go to the od to get something near .022 going there. if the amp is hrm, then some caps (cl2 and od2) might be 1uf...someone correct me if i'm wrong. Also hrm doesn't have the LNF in cl2.
i guess we were expecting something like this schem long time ago....thanks for the effort!!

[tictac]

I've never liked the idea of having high voltage DC on those mini front panel switches, sure it probably would short to ground if there was a problem but why not simply put the mid-boost switch after the 390pf cap and short out the .002 cap instead?

My .02

[HiGain]

Thanks for the feedback, guys. I will update the schematic according to the corrections. The goal is to produce a schematic that is at its bones the real thing. A starting point before modifications.

Jake

[Funkalicousgroove]

There is absolutely no reason to put the mid boost switch before the coupling caps, Put the .0022 on the board, run a lead from that to the center leg of a spdt, put your 330pf cap across the top and bottom legs of the spdt, and your lead going to the treble pot off the bottom leg of the switch(as well as the 4.7M to ground. Switch up= 2200pf, switch down=286.95pf

[jaysg]

I'm not sure there's any advantage to splitting the 22M R's at CL2 feedback. It may be easier to package the resistors in series with each other. I put it right on the socket. Not sure what the real deal is like.

Re: below...facinating and odd

[Funkalicousgroove]

Real deal has 22m on either side of the .05 cap

[Robert]

Thanks for sharing your work. It is a great idea and a nicely drawn schematic.

[Ed de Jager]

Hi,i just wat to say i am happy with this thread because i am new here and don`t know just where to start.
In my opinion it is a great help to have a sort of *starting from* schematic tweaking and tuning can be done after the basics are done right but one has to know the basics first first.
Thank you for providing this info!
Greetings,Ed