What HRM schematic to use?

[benoit]

I had been planning on going with the ODS-101-HRM schematic, and still may, but after comparing it to 124 I'm not so sure that's what I want to use. I realize 124 is non-HRM among other differences but it raised questions.

1. In 124, the mid control says it's labeled as "deep." In ODS-101, there are separate controls for both mid and deep. What does that deep switch do?

2. In ODS-101 the rock/jazz switch is omitted. Why is this? I think I remember reading ages ago that some people didn't find it useful. Is this the reason?

3. Am I correct that the PAB relay and PAB switch are wired in parallel, so that if no footswitch is plugged in, the PAB depends solely on the switch, and if it is, switch on means PAB on and switch off means footswitch controlled PAB?

I guess what I'm wondering is basically this: am I missing something by not including the jazz rock switch, and is there a better HRM schematic to work from than ODS-101?

[Fischerman]

I'll take stab what little I can:

The deep switch sucks out some mids...in a way it sort of takes the preamp back to a more BF Fender sound. I can see how some people might like it but it never really did anything for me and I yanked it out of mine.

I read the same thing about the Rock/Jazz so I never even tried it and thus can't really comment.

I think only the relay contacts are shown on the schematic...and the switching isn't shown so I guess how you arrange it is up to you. But I thought the panel switch just engaged/released the PAB relay (and you can make it footswitchable but I must admit the footswitching of the real things is something I know the least about regarding these amps). FWIW - in my amp I arranged it with a 3-position ON-OFF-ON switch such that the PAB is either always ON - always OFF - or auto-engages w/OD. And that switch almost always stays in the 'auto-engage w/OD' position.

Also, FWIW/IMO - those schematics show relay contacts and panel switches as identical components and there really should be something that differentiates that the PAB and Channel Switch are relay contacts and the Bright/Deep/Mid-Boost are panel switch contacts. Maybe add a little coil to them or something? But in any case...they were the ones I used to build mine and I'm grateful they were available. I was also told they are about as good (and accurate) as anything here (as a baseline/accepted value schematic)

[Bob-I]

To begin with, the basic architecture of all these schems is abot the same. Don't get too wrapped up in this, you can test all these changes later.

I had been planning on going with the ODS-101-HRM schematic, and still may, but after comparing it to 124 I'm not so sure that's what I want to use. I realize 124 is non-HRM among other differences but it raised questions.

More info is needed. What type of sound are you going for? The aggressive rock sounds of the Non-HRM or the more polite OD of the HRM. Personally I use the HRM and play pretty hard rock stuff with it.

1. In 124, the mid control says it's labeled as "deep." In ODS-101, there are separate controls for both mid and deep. What does that deep switch do?

I tried a deep switch in one of my amps. I felt it made the amp muddy, sucked mids and I removed it. The mid boost is far more usable.

2. In ODS-101 the rock/jazz switch is omitted. Why is this? I think I remember reading ages ago that some people didn't find it useful. Is this the reason?

Again, not really very useful. It kinda mellows out the amp by removing highs and lows and leaving the mids a bit thin. Not my thing at all.

3. Am I correct that the PAB relay and PAB switch are wired in parallel, so that if no footswitch is plugged in, the PAB depends solely on the switch, and if it is, switch on means PAB on and switch off means footswitch controlled PAB?

Yes

I guess what I'm wondering is basically this: am I missing something by not including the jazz rock switch, and is there a better HRM schematic to work from than ODS-101?

Nope, that's a good one to start with. Now start soldering

[Fischerman]

Personally I use the HRM and play pretty hard rock stuff with it.

Me too...mine has been tweeked to be almost high gain. One of these days I'll make my first ever internet clip...but compared to most of the clips here my amp just doesn't sound that 'Dumbly' (to me...with me playing...anyway). It sounds more Carol-Ann-ish (based on the CA site clips) but just not as good.

[Bob-I]

Personally I use the HRM and play pretty hard rock stuff with it.

Me too...mine has been tweeked to be almost high gain.

I didn't really add any gain, I don't like the mud that comes with too much gain. If you go to my band's site below there's some recordings from the board (our first ever gig so there's lots of clams)