On the Overtone, the switch labled "Deep" is a "Mid-Boost." Some original Dumbles that were made with the "Deep" circuit, were converted by Mr. D to a "Mid-Boost" and I don't think the label on the switch was ever changed by Mr. D. So, Niki's amp is like one of these converted Dumbles.

About the schematic, I cannot imagine someone building an amp without one, so I suspect Niki has one. If he wants to post it then that should be up to him. Personally, for my project using Niki's kit, I drew up a schematic by following the circuit in the layout posted here. My project has a different power supply, different transformers, slightly different grounding scheme and is 100W, so it does not exactly match the pre-built Overtone that Nike sells. I have no problem sharing it on this forum if it is OK with Niki.

Hi,

I got the chassis locally, but from the looks of it, it is available on the internet. The chassis came screen printed with all the lables.

Since I used Hammond replacement/reproduction Fender Twin transformers. They are made in USA and Canada and are reasonably priced. I got in on a "Holiday Special" and got free shipping (25LBs!) when I ordered the transformers. I chose Fender Twin transformers because thats what Mr D used in the 80s. Niki's amp is a clone of an 80s style amp.

The original output transformer only has a 4 ohm tap (just like an 80s style original amp). The chassis I have only has the single 4 ohm speaker output also, so everything fits together like the original. This output transformer is also for four 6L6 tubes.

The power transformer only has input taps for 120v and has no 6v output. This is different than Niki's transformer, but it is exactly like the original 80s amp.

More dependent on the tube design. The 6L6s have a certain heat that they can tolerate and beyond that they can fail or have a shortened lifespan. There are volumes written on biasing. The 'D' amp that the Overtone is based on had an output section like a 100W Fender twin (which Mr D copied) . So you can research 'biasing fender twin' on the net as I suspect the bias settings should not be different weather you have a 100w or 50w version.

Again, you can read pages and pages on biasing but it does come down to adjusting the trimmer pot to where it sounds best and measuring cathode current to make shure you are not pushing the tubes too hard.

The advantage of having a number to go by lets you set the amp to a reasonable bias setting (that has worked for you for other similar amps) while on the bench, without having to hook up a guitar and speaker.

Did you guys get an e-mail from Niki telling you your amp shipped, or did it just show up? Can't wait for mine to get here but I don't want to keep bugging Niki with e-mail "is it ready yet..." I'm waiting on a kit/parts so I hope it is not 6 weeks. Did Niki say how long for the kit?

I don't even have my kit yet, but after my build I will be biasing my 6L6s around 35ma.

I know what you are talking about on the overtone layout. I am using regular Switchcraft jacks, so I don't know how the pins on those jacks Niki is using are wired. Here is a schematic that shows how I am wiring the jacks.

50/100 switch and LED.

Updated shot of the chassis.

Likewise, on my chassis I used the washers over areas that I scrapped with a Dremel. Turns out, on the original, these speaker output jacks get the ground through the chassis, where as many of the other components have a separate ground wire.

I think the originals were anodized also. Here are some pictures of where I believe Mr D used these star washers to ensure adequate ground on the components that need to be grounded to the chassis.

I got the chassis at a swap meet here in the states. I don't know where it originally came from, do you have a link to songwut's chassis? Maybe it matches.

Here is another picture of the underside. Unlike Niki's power transformer, the original Fender transformer does not have a 6v tap for the relays and Leds. So, like the original D amp, I have added a small 6v transformer.
http://img.photobucket.com/albums/v670/ic-racer/t_6v_pt_846.jpg

If anyone is interested in specific part numbers on the transformers let me know, am glad to share the info with anyone else building an overtone.

I'm kind of in the same boat as all of you waiting for my overtone parts. I have ordered the boards and hardware and cabinet to use for my project.

Here is the chassis that I already have, getting some original Switchcraft components (redily available in USA).
http://img.photobucket.com/albums/v670/ic-racer/Chassis2.jpg

As you may know, Nik's version of the overtone is 50w. I am re-creating an amp with 100w output. This requires a custom powersupply (to match the original D amp). The original had 300uf capacitors, which are difficult to locate.
http://img.photobucket.com/albums/v670/ic-racer/BigCaps.jpg

Since the original used Fender transformers, these are easily available in the USA, so I have these already installed on   the chassis. http://img.photobucket.com/albums/v670/ic-racer/Transformersinplace.jpg

Unfortunatly, I must wait for my parts from Niki to do any more with the project.