New ODS-101-HRM layout

[benoit]

Hey folks. I've been slowly working on a build for months now of an HRM that will initially use all ODS-101-HRM values. I've had all the parts for a while and have some of the holes cut in my DIY chassis, but felt like I'd better make a detailed accurate layout to ensure that I don't screw something up as far as leaving room for everything and not putting things in places they shouldn't go.

So naturally I decided to draw a layout. That's been really helpful in terms of seeing how everything lays out physically. I originally intended this layout just to be for my build but then I thought I'd try to contribute a little by basing the layout as closely to 101-HRM schematic as possible, since I have never seen a layout that has all those exact values. I'm not 100% sure that the ODS 101 schematics are super relevant now that there's so much info available on 124 (if my impression that ODS101 is more an conglomeration of values from various dumbles rather than an specific one), but it seems like new people are always pointed to the ODS-101 schematics so I thought it might help people ease into a build a little better if there was a layout to go with it. I also wanted to do it in such that it could work for someone using a funk chassis, since so many people seem to go with them (which I should have done - chassis are a PITA to DIY, let me tell you, and mine won't be half as pretty as Brandon's).

I've got this layout about where I want it, at least for the ODS101 schematic. I didn't put in test points yet because I wasn't going to include them in my amp and had forgotten that they were in the schematic. If I were to omit them would I still need the resistors to ground? I also forgot to add the pilot lamp.

I realize the wiring is a little messy and I could probably get rid of some of it and/or tidy it up. Any comments on how to make the layout more elegant/readable are welcome, as is proofreading.

I will be building basically this circuit, then adding relays once I get everything working without them. I may do a version of the layout with the FET input board, in case people want to include that. I personally chose not to, as I've never heard anyone say they liked it.

Anyway, please check it out and let me know what you think.

Ben

EDIT: I should also say a big thanks to everyone who has worked on schematics, layouts, etc. I know normster and mdroberts' layouts helped a lot, as well as the OTS layout and various others, but I pulled symbols and ideas from a ton of different places and I appreciate all the people that made it available.

[benoit]

I know no one owes me a look at this but if someone could give me any feedback at all that would be awesome. I don't need someone to check every last value and connection, but comments overall on how things are laid out (e.g. "well that works, but it might be easier to do it this way") and on whether there are any glaring problems would be cool.

I don't mean to sound like I'm trying to pass the buck or get out of checking it myself. I have checked and will check again before I build. I'm just really green and am trying to ensure I don't screw myself over.

[Stanz]

Excellent, thanks. I am doing a 100W HRM right out off of the ODS-101 schematic and have had to cobble together several layouts to get a grasp on where I am going with things.

[benoit]

Excellent, thanks. I am doing a 100W HRM right out off of the ODS-101 schematic and have had to cobble together several layouts to get a grasp on where I am going with things.

Cool. If you've got any insight or suggestions to offer I'm all ears.

Ben

[stelligan]

Ben,

I can't offer any suggestions or critique at this point - only a heart felt thank you. I don't really consider myself a builder and have trouble with schematics at times. A layout will be of great help when I finally begin an HRM build in my Funk chassis.

Thanks,
Dave

[skyboltone]

Good work Ben. One of these days I'm gonna do a #124 tubes up layout in Visio. It's a ton of work I know, but surprisingly satisfying.

Dan

[benoit]

Good work Ben. One of these days I'm gonna do a #124 tubes up layout in Visio. It's a ton of work I know, but surprisingly satisfying.

Dan

If you think it'd help PM me your email and I'll send you the visio file for my layout.

Ben

[skyboltone]

Good work Ben. One of these days I'm gonna do a #124 tubes up layout in Visio. It's a ton of work I know, but surprisingly satisfying.

Dan

If you think it'd help PM me your email and I'll send you the visio file for my layout.

Ben

I've got one Normster started but it's, like yours, tubes down. Sure send it along. skyboltone at yahoo dot com.

Dan

[heisthl]

Initial impressions - good work but no relays, also "real" pics I've seen had first filter charged before standby switch - choke and OT on other side. Separate the grounds for B+4 and B+5 caps away from the other nodes so they can ground at the input jack (ground rail for pots). Try the old style dropping string initially - choke,3k,22k,2k2,150k to ground (unless you have the FET circuit). Hard to tell from your layout but the 390R "tail" should ground at the send/recieve jacks and the presence pot should have no connection on pin 3. Another nitpicky detail - make the 150K slope a carbon comp unstead of a VDale type, ditto for the OD entrance resistor and change the PI plates to just standard MF types.

[moj067]

Thanks for the effort. I'm going on the mdroberts layout and yours just gives another look at the amp. A choke-resistor switch would be a nice addition to this layout. I'm sure many will add to this wish list.

[benoit]

Initial impressions - good work but no relays, also "real" pics I've seen had first filter charged before standby switch - choke and OT on other side. Separate the grounds for B+4 and B+5 caps away from the other nodes so they can ground at the input jack (ground rail for pots). Try the old style dropping string initially - choke,3k,22k,2k2,150k to ground (unless you have the FET circuit). Hard to tell from your layout but the 390R "tail" should ground at the send/recieve jacks and the presence pot should have no connection on pin 3. Another nitpicky detail - make the 150K slope a carbon comp unstead of a VDale type, ditto for the OD entrance resistor and change the PI plates to just standard MF types.

Thanks for the look, esp the grounding info. I'm not going to put in relays yet because I wanted to draw ODS-101-HRM, the whole ODS-101HRM, and nothing but ODS-101-HRM. As this is my first D-amp I'd like to wire it up without relays to begin with and then add them once everything works. I realize that I put the footswitch jack in that drawing so maybe I should take it out for now.

Or perhaps it would be better to just include the footswitching right away? Would it be more of a pain to add later in terms of actually building (not drawing in visio)? Even people trying to follow ODS-101-HRM to the letter are probably going to want a footswitch.

Anyway I'll update when I get a minute or two.

[HiGain]

Looks good I'll look it over tonight. It's probably best to create a layout that matches closely the real thing, for which you can use the *umble pics floating around here, as well as Brandon's, who followed closely the real deal.

The reason why it's important to follow the layout is becuase lead dress DOES matter with this amp. Asside from the issue of stability or oscillation, it matters for the perceived character of the midrange and treble. Trust me!

I also have minor updates to the schematic, which will not alter your layout, BTW.

Thanks for the effort!

[Stanz]

As a suggestion, nothing wrong with having a few different versions of layouts. As we can see, many different approaches. The one size fits all never really works in the end. I do like the idea of the strictly ODS-101 HRM layout.

[benoit]

Looks good I'll look it over tonight. It's probably best to create a layout that matches closely the real thing, for which you can use the *umble pics floating around here, as well as Brandon's, who followed closely the real deal.

The reason why it's important to follow the layout is becuase lead dress DOES matter with this amp. Asside from the issue of stability or oscillation, it matters for the perceived character of the midrange and treble. Trust me!

I also have minor updates to the schematic, which will not alter your layout, BTW.

Thanks for the effort!

I agree about keeping the layout basically the same. As far as front and back panels, I basically eyeballed the pics of 124 aside from leaving a few things out (like the ground switch and half power switch) and adding an impedance selector. As for the guts I don't have any pics of the precision power supply in a real d-style but have mine set up according to a normster (I think) layout. The preamp board is pretty darn close as well. I will definitely leave room in the layout for relays done as close to the real thing as possible. I also left out the FET input, as no one seems to include it except for authenticity's sake and because it's not in the ODS-101 schmatics, and leaving it out doesn't really change any layout things except leaving more space in the chassis.

It's important to note that my layout should NOT be used as a guide for lead dress. All wire connections are meant simply to represent that two points should be connected by a wire with no regard to how that wire should be routed. In this case there are really no substitutes for good gutshots. Again thanks for the input and I agree wholeheartedly.

Also remember that this layout is meant to be nothing but ODS-101 HRM and that I will be doing a fleshed out version for my actual build.

What revisions to the schematics would you make and why?

As a suggestion, nothing wrong with having a few different versions of layouts. As we can see, many different approaches. The one size fits all never really works in the end. I do like the idea of the strictly ODS-101 HRM layout.

Amen. I plan on doing at least two, as I said earlier. One strictly ODS-101-HRM and one with relays also.

[dogears]

A few things, this particular Dumble that this layout was based off of was an EL34 amp. I would build that as all the examples I have seen of Dumbles with this topography were EL34. So, 1K screens on the outputs (check out anyway as you have a mistake). The masters are 1M. Midpot is 250Ka.