New 100W non-HRM born in a Funk chassis

[mlp-mx6]

Here is my latest amp, a 100W non-HRM. I used Twin iron including a 4/8/16 OT from Brandon and a Hammond Twin PT. The chassis was a joy to use.

I added an IEC power inlet with integrated fuse. I have not yet implemented the FET input. Instead I used that slot on the sidewall to install a 2nd relay connected to the OD switch to turn off Bright when in OD mode. I used a 5-pin XLR for my footswitch connection. (DMX cable)

220/150 220/150 for the plate resistors. Basic ODS-101 circuit, except I have Rock/Jazz instead of Deep (this is what the chassis said, so I had to go that way). Interestingly, there is not a solid reference schematic for Rock/Jazz with the 101 circuit.

I did use all RV4 pots - most are NOS 2W pots. I had hoped to use an old 10K locking pot for the bias control, but there was not room for that pot with the power supply board at the proper height.

I used a 12.6V Radio Shack xfmr (0.45A output) bridge rectified and regulated for my 12V supply to the relays and the LEDs on the footswitch and the pilot light.

My footswitch controls OD, PAB, and Mid boost (the black relay board).

So far I'm LOVING this amp. It has that "vowel" quality that others have mentioned. I'll try to find a way to record a clip - I am not set up to do that at this point.

I'm wrestling to get pictures uploaded to this forum, but I'll keep trying.

[mlp-mx6]

Here she is.

[mlp-mx6]

Initially I had EH 12AX7s in V1 & V2. Once I switched those to JJs the tone sweetened and the noise dropped. I am amazed at how quiet this amp is at idle in OD mode. It's wonderful!

[tubedogsmith]

Did you install a 150k dropping resistor at the V1 filter cap to compensate for the FET circuit? This will bring your preamp voltages in line.

[mlp-mx6]

As of now, no, as I am still deciding whether or not to install the FET board. I manipulated the dropping string to get the preamp voltages to where I wanted them (which is according to convention).

[Structo]

Sweet looking build.

What size of mid cap are you using?

[mlp-mx6]

Caps are straight off the ODS-101 schem, so it's .01 for the mid cap.

Yeah, a Strat is not it's favorite guitar. Tele works well, though.

[Structo]

Weird huh?
Both single coils.

What I did on my amp was to install a small toggle on the back to switch between midcaps.
I have a .01uF on the board and a .047uF on the switch.
It adds the .047uF in parallel so I get .01 and .057uF when switched.
Kind of a Fat and Thin switch.

I plan to also put a switch on the LNFB loop on V1.
I already have the holes in the chassis there from a different effects loop I had before I built the Dumbleator.

If you don't have the D'Lator yet, I encourage you to build one.
I put that off for way too long, it really helps these amps.

[bigmik]

man I LOVE seeing all these new amps being built gives me the icth for another, well maybe just dumbelator for now

NICE AMP!!!

[David Root]

Another really nice build! Great stuff! It must be winter, we are all down in the basement just knocking them out!

I am thinking about a Music Man HRM, anyone have opinions/experience with that combination? Or is it best to do a standard ODS with the 700V plates?

[mlp-mx6]

Thanks, folks. It is SO rewarding building an instrument such as this. Dare I use the term "ampstrument"?!?

Yep, down in the basement working on amps this very cold winter - cold even in Atlanta!

I'm buying the parts for D'lator right now. I have 2 amps with a built-in D'lator, but I need a standalone one too. OK, I *want* one.

[mlp-mx6]

One other comment. For a long time dogears had told me that a 100W is the way to go. Though I believed him I had not tried it. I have 2 other 50-watters and a 20W guy. The *feel* of this 100W just destroys all the others. There really is something about the feel, the girth, of a 100W output section that is a quantum leap above all the others.

[UltraHookedOnPhonix]

Sweet build!
Why is there a 47pF cap across the PI plates? It doesn't appear you used a BM PI.

[mlp-mx6]

Correct, it is not a BM PI, it is a standard ODS-101 . The 47pF is a trial tweak that may or may not stay. It cuts a *little* high end out of the PI.

The other tweak - that I also may revert - is the resistor following the OD2 coupling cap is 180K rather than 150K. This darkens the OD tone ever so slightly.

I *really* like turning off the bright in OD mode but having it there in clean mode.

[Luthierwnc]

I use two OD relays. One does the usual. The other opens the circuit on the bright cap when in OD mode. It is just a series connection between the pot lugs in the N/C position.

The #2 side of that relay disengages the V2 NFB loop in my non-HRM. A switch in the back determines whether the loop is always on, always off or controlled by the OD relay. I've thrown in a diagram.

Works well and on the HRMs it keeps the clean master from bleeding highs to ground in OD mode. Skip