Diplomat - Matchless DC30's EF86 Channel

[vigilante398]

Alright, I kind of teased this one a bit ago in the Echo Foxtrot thread as this is the reason Echo Foxtrot has been discontinued. Diplomat is based on the EF86 channel of the Matchless DC30, my favorite amp ever. Since this is a single pentode stage it will not overdrive by itself, but you can put a boost or drive before it to push it, or you can use it as a clean boost to push something else.

It's a pretty straightforward build, especially if you've built anything else by me before, and it uses the same general setup as Particle Accelerator. It has two controls: a master volume, and an 8-way rotary Tone selector. The original only used a 6-way, but I went for an 8 partially because they're more common and partially because I wanted to add some extra values to make it work better as a bass preamp.

I have a couple dozen boards on hand and ready to go and have some enclosures being milled now, but I still need to finish getting the build doc put together before I can list them for sale.

It sounds fabulous, especially driving another tube preamp (my use of choice) or being driven with another boost (still very good). I will mention it's very loud, but obviously there are steps that can be taken to tame it down a little if you don't need to push a power amp. I have a handful of NOS EF86 I picked up, but I have probably 50 or so "winged C" 6Ж32П so I use those most of the time.

 

[Silver Blues]

Hehehe. Looks great, I'll be grabbing one for sure.

 

[benny_profane]

Nice one. This is one is definitely intriguing. Did you mention the tubes because you’ll be selling those as well?

 

[vigilante398]

Nice one. This is one is definitely intriguing. Did you mention the tubes because you’ll be selling those as well?

I wasn't planning on it, but maybe I could? I used to sell an EF86 pedal so I stocked up on tubes, then I discontinued it and was left with a stash of tubes. The tricky bit is that EF86 are more likely than other preamp tubes to go microphonic, and some of the ones I have are certainly more microphonic than others. I would have to go through and sort out the unusably noisy ones and see how many I have left.

 

[benny_profane]

I wasn't planning on it, but maybe I could?

Yeah I’d pick one up along with the board/enclosure for sure.

 

[music6000]

Something Like This:

 

[zgrav]

Does a silicone ring around the tube tamp down the microphonics? And is there clearance for a silicone ring on this build?

 

[vigilante398]

Does a silicone ring around the tube tamp down the microphonics? And is there clearance for a silicone ring on this build?

A solid question. They should tamp down the microphonics a bit, most EF86 amps I've seen use the dampers on the EF86. I have some around somewhere, I'll have to see if I can fit them in the pedal. It wasn't specifically designed to be able to fit dampers, but they still might fit, it just may be a bit tight.

 

[zgrav]

A solid question. They should tamp down the microphonics a bit, most EF86 amps I've seen use the dampers on the EF86. I have some around somewhere, I'll have to see if I can fit them in the pedal. It wasn't specifically designed to be able to fit dampers, but they still might fit, it just may be a bit tight.

I appreciate the design is already using the available space inside the enclosure, so this is one of those "great if it fits, but OK if it doesn't" sort of questions. Or maybe a smaller ring would fit at the narrower glass base of the tube and still provide some damping.

In either case, I am looking forward to placing the order.

 

[music6000]

Does a silicone ring around the tube tamp down the microphonics? And is there clearance for a silicone ring on this build?

Use to put something similar on male sheep, took a couple of hours for them to settle down!

 

[Robert]

Use to put something similar on male sheep, took a couple of hours for them to settle down!

A lady I used to work with talked about doing that on her boyfriends farm..... then would continue on to mention how the sheep didn't like her.

No shit?

 

[Passinwind]

A lady I used to work with talked about doing that on her boyfriends farm..... then would continue on to mention how the sheep didn't like her.

No shit?

I'll bet there was mucho shit involved!

 

[vigilante398]

Use to put something similar on male sheep

A lady I used to work with talked about doing that on her boyfriends farm

Pretty sure it gets done for the same reason as on an EF86, based on my understanding of sheep and pentodes.

 

[Betty Wont]

Does a silicone ring around the tube tamp down the microphonics? And is there clearance for a silicone ring on this build?

I use them and they fit just fine on my GTO build. There appears to be about the same clearance on this design. They also act as bumpers that protect the tube should the pedal be jarred enough that the glass could impact the metal of the enclosure. I used 7/8 x 3/4 x 1/16 silicone o-rings

 

[benny_profane]

I use them and they fit just fine on my GTO build. There appears to be about the same clearance on this design. They also act as bumpers that protect the tube should the pedal be jarred enough that the glass could impact the metal of the enclosure. I used 7/8 x 3/4 x 1/16 silicone o-rings

Did you get your builds up and running?

 

[Betty Wont]

Did you get your builds up and running?

I was successful with the revised version. The the first edition attempts all ended up in the bin unfortunately.

 

[benny_profane]

I was successful with the revised version. The the first edition attempts all ended up in the bin unfortunately.

Ah. Sorry to hear that. No luck with the latest buffer breakout?

 

[vigilante398]

Just finished updating the build doc, the only thing missing (as usual) is the drill template. I'll get it uploaded when I get home from work and I'll try to make time in the next day or so to see how many EF86 I have on hand that I would be comfortable selling, then I'll make boards available on the website.

 

[zgrav]

The build doc looks great. Really impessive to see how much time and detail you put into thosel

 

[vigilante398]

Mmkay, I finally pulled out my tube stash to look through, I have a total of 29 Winged C 6Ж32П. I already tossed a couple because it looked like the seal was going bad and the getter flash had faded, I'll go through these and see how many test good for me to be comfortable selling them. I should be able to get that done by tonight, I'll let everyone know when boards are available for sale.

As a clarification, these will be available for purchase with PCBs while supplies last, I don't plan on consistently keeping a stock of tubes on hand for this purpose.