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GB: Millett UniAmp PCB groupbuy
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Author:  Bluesman [ 17 Apr 2009, 19:09 ]
Post subject:  GB: Millett UniAmp PCB groupbuy

Current Group Buy Status: CLOSED - See Interest Check for more Millett UniAmp PCBs for a potential 2nd round.

I placed a small order for Millett UniAmp PCBs this first time to get an idea of interest from my fellow DIYers, with further orders possible. Estimated delivery date is May 11. These will be shared at my actual costs plus shipping. This initial quantity is limited to 10 pair, so please advise in this thread if you are interested. Boards will be reserved in the order of posting. I would like to limit it to one pair/request initially. Don't know of a more fair way to do it. Cost is not yet certain, but if my 50% new customer discount is applied correctly, it appears to be less than $20/pair, depending on shipping charges to me, and any other costs I may not be aware of. Again, this is not-for-profit to me.

Please visit Mr. Pete Millett's site at the link below. For those who may be brand new to DIY, Mr. Millett is well known, both as a contributor to the DIY sector and commercially, formerly doing business as Wheatfield Audio. He is a regular contributor to DIY magazines. His Millett Hybrid headphone amp/preamp is near legendary status. I personally have built at least a dozen of them.

There is a lot of info on his site about the UniAmp. The boards are each for a single channel. Very slick connection set-up. Power tubes are chassis mounted off the pcb. Mr. Millett even has an example of his chassis layout. It's a push-pull design, and can be used with KT88s, EL34s, 6L6s, 2A3, and even 300Bs with few, if any changes needed in component values. Should be a fun build. I'm ready for a nice pcb after a couple of point to point builds.

Again, please respond here on this thread if you are interested in a pair of these boards. If needed I can place another order. I have "new customer" status with Imagineering, Inc. and get that 50% discount until I spend $2000 or until October, whichever comes first.

Here's another example of Mr. Millett's work. ... ts_id=1193

Cheers, Greg

Author:  booangler [ 17 Apr 2009, 20:10 ]
Post subject:  Re: Millett UniAmp PCB groupbuy


If you are looking for participation, I would be interested in a pair.


Author:  Bluesman [ 17 Apr 2009, 20:27 ]
Post subject:  Re: Millett UniAmp PCB groupbuy

Thanks, Alan!

Yes, this thread is to offer the extra ones I have to other DIYers. Guess I should have made that a bit more clear.

Author:  Gio [ 18 Apr 2009, 12:18 ]
Post subject:  Re: Millett UniAmp PCB groupbuy

Yes, I will take one pair.

I'll be setting up a For Sale / Wanted / Group Buys Forum shortly and then I will move this post in there.

Author:  Endspec [ 19 Apr 2009, 21:31 ]
Post subject:  Re: GB: Millett UniAmp PCB groupbuy

I was thinking of a pair myself but the phase tranny might be a problem for me, is there something else that can be used inplace of it?

Author:  Bluesman [ 20 Apr 2009, 04:10 ]
Post subject:  Re: GB: Millett UniAmp PCB groupbuy

EndSpec, Don't know how to implement it exactly, but using a tube as the phase splitter is very common in older equipment. I have vintage Silvertone and Sherwood amps that both use that method.

Cheers, Greg

Author:  Endspec [ 20 Apr 2009, 06:51 ]
Post subject:  Re: GB: Millett UniAmp PCB groupbuy

yes Greg all my tube units use small tubes for this, I am hoping some one might know how to convert it over to a tube phase unit.
Steven A.

Author:  Dan [ 20 Apr 2009, 18:00 ]
Post subject:  Re: GB: Millett UniAmp PCB groupbuy

Pending freight costs to Adelaide, Australia. at 20usd each pcb i will be in for one pair.


Author:  Bluesman [ 20 Apr 2009, 18:40 ]
Post subject:  Re: GB: Millett UniAmp PCB groupbuy

Endspec, wouldn't you know there was a group buy a month ago on for a domestic replacement for the Sowter. ... did=139408

I think I'll stick with the Sowter. May go ahead and try all Sowter transformers. What the heck! I'm planning to make these UniAmps a very nice looking pair of monoblocks that I'm going to keep, so I may go all out.

Dan, I received price confirmation from Imagineering. The production cost is going to be right at $15.50/pair USD, plus shipping. Costs above and beyond that will be actual shipping fees to you guys, a few padded envelopes, and Paypal fees. I have no experience so doing so, so I can't say what shipping will cost from here to Down Under. I'll leave that to you to estimate for reasons of deciding whether to join in or not.

BTW, do you know any Bloomfields? That's my surname. I talked to one of Tommy Emmanuel's reps a while back and she said Australia had lots of Bloomfields. Figured it must be some long ago convict relatives sent there from England. HA! HA! I'm related to Staffords too, so I'm sure they're there, as well.

Cheers, Greg

Author:  Bluesman [ 25 Apr 2009, 14:31 ]
Post subject:  Re: GB: Millett UniAmp PCB groupbuy

FWIW, I received a message from Imagineering that the order is in production and will be shipped before May 11.

FYI, I'm going to make a mention on a couple of bigger forums about having these, so if anyone is on the fence about wanting a pair of these boards, speak up. There are only 6 pair left, as I'm holding a pair for Endspec and Dan, in case they want them. Anyone can back out if they want. I'm in no hurry to get rid of these, and I feel certain I can unload as many as I need to elsewhere, if it comes down to it. Would just rather do it here first.

My short term plan is to try to help develop a definitive parts list. Not recommendations for brand names, etc., just components, their values, and their spacing or size limits on the board. I've been working on it some with the limited info I have. I used the schematic posted on Mr. Millett's site to come up with a rough idea of what we need.

I would love input from experienced builders to advise on what type of component to use for each spot on the board, and why. For example, should we use a really nice quality .22uf cap for C2 and C3, or is it just as well to use some generic part. That kind of thing.

On each pcb there will be 24 or 25 resistors, depending if you use NFB. 13 capacitors, 7 electrolytics and 6 films. Also the phase splitter transformer and a pair of 6SN7s and the rectifier tube. I read a short thread on and some guys mentioned having problems getting their holes spaced correctly in their chassis for alignment with the pcb mounted tubes. This can make a real hack job of a nice chassis, but I know from experience it's not that difficult if you plan ahead, measure properly, and then cut properly. If you do pcb mount the tube sockets, then you have to do a decent job of aligning with the cutouts you make in the chassis. As a last resort, you could chassis mount all the tubes and run wiring to the pcb, or if you goof up, buy some of these; ... d=1021#613

Off the pcb there will be 5 or 6 transformers and chokes, depending on if you build monoblocks or use a single chassis design. 4 more tubes, and the usual chassis jacks, fuse holders, power cord, IEC power inlet, wiring, etc. And of course the chassis itself, and probably some things I overlooked.

Cheers, Greg

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