New ODS-101-HRM layout

[benoit]

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.

Hmm.. I was planning 6L6. I went with the Twin iron from mojotone.com. Is that going to be a problem with this layout?

I feel kind of silly because I didn't give a whole lot of thought to tube type in relation to schematic/layout/values.

In any case I very much appreciate the look. I'm starting to get an idea of why such a schematic didn't already exist

[heisthl]

the ODS-101 schematics sound great as drawn - 6L6es and all, and require minimal,if any tweakage. If you build it the tone will come.

[dogears]

6L6 is fine. No issues.... I was only suggesting if it were a fresh build. In any event, check the masters. You have a 100K on the OD. Also, make sure you use a treble trimmer in the HRM that measures aroudn 250k-260k. You can add a resistor in sereies with the treble cap to raise the value. Those trimmers can be all the way down around 210k!

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.

Hmm.. I was planning 6L6. I went with the Twin iron from mojotone.com. Is that going to be a problem with this layout?

I feel kind of silly because I didn't give a whole lot of thought to tube type in relation to schematic/layout/values.

In any case I very much appreciate the look. I'm starting to get an idea of why such a schematic didn't already exist

[ic-racer]

Looks like you put a lot of time in this, good work. The only thing I can comment is that personally I would like to see a layout that is as close to the real deal as possible. Since component location dictates lead dress, and lead dress is so important, starting with everything in the right place would be good.

These pictures all came from this forum, but you mentioned you had not seen pictures of the power supply, so here they are.

[ic-racer]

Close up of the power supply cap board.

[benoit]

ic-racer: thanks for the pics.

Question: When you said you wanted to see the layout more like the real thing did you mean in terms of overall layout (like, where the main board sits in relation to the power board in relation to the PT cutout) or more in the details (power supply board layout, for example)?

There were some compromises I made simply because I don't have the knowhow to manufacture PCBs and had to come up with my own way to do it (or cop someone else's, as the case may be )

Specifically what would you change?

[ic-racer]

Specifically what would you change?

Your layout is pretty good, so these are just little details.

Location of the Larger power resistor on the cap board near the upper side
Arrangement of the grid resistors on the power tubes
Space for the Fet input jack
Spacing of the components on the rear panel. (These all may be insignificant, but for example, if the effects jacks are not in the right place, the signal wires that come from the front of the amp may have to cross over things that they shouldn't.)
Footswitch jack (DIN instead of Switchcraft)
Power input (standard cord)

Not that I am trying to change the way you build yours , but maybe have two layouts, one that shows how you did it and a 'Gold Standard' layout as a universal reference based on the real ones.

Here is another picture that you may not have seen, it is Gil's HRM build.
All the pictures (and Gill's HRM build) have 2 capacitors on the rectifier board. I'm not an HRM expert yet so I'm not sure about the discrepancy.

[Structo]

The only problem I have with the layout since I'm not knowledgable enough to point out errors is probably a software issue related to the program you are using.
I find it difficult to follow the wire paths because of the small lines drawn.
I know that the Visio (sp) program is great but has a bit of a cure to learn it but when I see layouts drawn with that ( Brown Note) I can easily follow the wire paths.
But still, nice job on the attempt to layout a great amp!

[benoit]

Location of the Larger power resistor on the cap board near the upper side

What resistor is this, I'm been checking out pics and can't seem to figure out what it's for.

Ben

[ryanf]

I have a question.

Is there any reason why the presence resistors and capacitors are mounted on the board? It seems to me like that just introduces more wire than is needed. Must it be this way, or will it work otherwise?

[ic-racer]

Location of the Larger power resistor on the cap board near the upper side

What resistor is this, I'm been checking out pics and can't seem to figure out what it's for.

Ben

Its the first dropping resistor.

[Bob-I]

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.

I'd suggest you look over the pics and re-route the leads. A good layout should represent the lead dress as well. At times a good layout looks like a mess, in reality it's because it's 2D. Lead dress is really critical in these amps, or any other sensitive amp for that matter.

Also I don't see the snubber caps on V2.

[Guitarman18]

benoit, it seems to me as though you have the cathode of V1a connected to the 2K2 cathode resistor and V1b connected to the 3K3. It's also difficult to see how the cathodes on V2 connect. They both appear to connect to the 1K8.
Also you have the 3K3 cathode resistor on the front panel side of the board (which seems to be the way Ayan has it on his HRM build) but I have always wondered why that is, the cathode lead of V1a needs to be twice as long as V1b. I've had real difficulties trying to figure this out as other pics that show close-ups of cathode resistors, tend to be builds with 1K5 cathodes on both V1a&b.

On V2 you have the cathode resistors set out the other way. (again, I can't help you here because most pictures have the cathodes resistors of V2 covered by the HRM board or goo.

Perhaps someone with first hand experience can shed some light on this issue? (Or should I not worry so much.......)

Cheers, Paul.
PS. It's a great piece of work. Many thanks for doing this.

Bob-I wrote:

Also I don't see the snubber caps on V2.

Don't forget it's an HRM layout.


heisthl wrote:

make the 150K slope a carbon comp unstead of a VDale type, ditto for the OD entrance resistor

Shouldn't that be Carbon film?

[heisthl]

Lead lenght on Cathodes is a non issue. Yes I meant carbon film although I've noticed lately at least one of the "real" amps has metal film there.

[Bob-I]

Did you notice that 2 of your screens are 500, the other 2 are 1K?