HRM 102

[ChrisM]

Getting ready for a 100W HRM build. Got the chassis, OT, PT and a few small parts so far. Putting together some part lists for Mouser and AES so I can work on this amp over the holidays.

Anyways this is the schem I have been referencing since I started my research. https://tubeamparchive.com/files/ods_102_hrm_158.pdf
It can be found in this thread https://tubeamparchive.com/viewtopic.ph ... ht=102+hrm

This is basically the 101 HRM schem but drawn much nicer by ic-racer. There are some slight changes though from the 101. Is this schem accurate? Also where did this schem come from? Pics of real amp?

Does anyone have a source for the main eyelet board? I cant make my own and don't really want to order from Ceriatone.

O and also how is the 25K OD trim usually set? I am thinking of maybe trying 50K or 100K, might make the trim pot a bit more useable, more gain?


Thanks...

[Structo]

Not sure which amp that is modeled after.
It has the high plates and I believe the Skyline tone stack.

I used a 100K OD trimmer in my amp.

Strange how that one has the 4K7 resistor from the trimmer to ground.

[ChrisM]

That 4K7 there is just to set the minimum gain. If it wasn't there you could set the trim low enough that there would be no sound.

The reason I ask if I should make it bigger is I have read a few posts about people "cranking" that control, would like a bit more out of it.

[Structo]

Yeah I assumed the resistor was there to compensate for the smaller trimmer.

What I have found is the OD gets way too fuzzy if you go beyond 12 o'clock.

I set mine around 35K wiper to ground.

[ic-racer]

This is basically the 101 HRM schem but drawn much nicer by ic-racer. There are some slight changes though from the 101. Is this schem accurate? Also where did this schem come from? Pics of real amp?

Someone a while back posted a link to a number of HRM photos, similar to the #124 photos. A number was not given but it was in the low 200s from what I recall. I analyzed the photos and updated the 101 schematic.

I know Chris has seen my thread, but others many not. I have been working on an HRM amp since I did that schematic but the progress is very slow https://tubeamparchive.com/viewtopic.php?t=9772

[ic-racer]

Here is the link. The pictures are all still there!

https://tubeamparchive.com/viewtopic.ph ... hlight=hrm

[George Adzich]

The HRM 102 Schematic is Great!

Is there a similar schematic available for the Non-HRM Version??

I would guess "Non-HRM 102"

[ChrisM]

Thanks IC, that is great. Very interesting seeing detailed pics of a ODS besides 124.

[ic-racer]

The HRM 102 Schematic is Great!

Is there a similar schematic available for the Non-HRM Version??

I would guess "Non-HRM 102"

Well, there is #124, and a number of variations.

If I were to do another non-HRM, I'd search for every post by ayan and read everything he wrote about 100k Skyliner amps and treble bleed.

https://tubeamparchive.com/search.php?s ... uthor=ayan

[ChrisM]

Does anyone have a source or have a main eyelet board for sale? I hoping to build this amp over the winter break but it will be hard with no eyelet board.

[mlp-mx6]

Can you make your own eyelet board? There is a layout in the Files section.

[ChrisM]

Can you make your own eyelet board? There is a layout in the Files section.

I cant unfortunately. I am away from home for another few weeks and I have no supplies to make eyelet boards.