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Alternate source for Millet-Hybrid PCB - Page 2  

post #16 of 589
Thread Starter 
Okay, so it seems like there's plent of interest in putting together the required order from PCB Fab - which only requires a quantity of 5.

I'll also follow MisterX suggestion of taking a lot at the alternate vendor.

I'm working with someone to modify the current board layout and I'll also be in touch with Mr. Millett to make sure that he has no issues with any of this. As I see it right now the group would like to make the following changes:

1. remove most board mounted components (jack, rca, power, switch)
2. make room for an Alps RK27 pot
3. modify buffer locations to allow use of DIP 8 components
4. compress the board as much as phsyically possible

At the current time I have no real desire to try any of the more exotic mods suggested like paralleling tubes or adding diamond buffers. This board will be for those of us looking to build pretty much a bone stock MH amp.

I'll update this thread when I have anything significant to add or for review of a modified layout. In the mean time I have no issues with people posting there interest but this isn't meant as a group buy thread, yet .


post #17 of 589
Sounds great. Count me in for a definite two if these come in at ~$20. Perhaps we can do a PCB later on with the spiffy upgrades after it's been built and tested.

post #18 of 589
This sounds interesting, I'm definitely subscribing to this thread

post #19 of 589
Thread Starter 
Okay, drewd has been kind enough to offer his board editing/creating skills as the board size is not able to be edited in the free version of Eagle.


At this time would anyone like to augment the list of changes I posted above? I'd like to keep this version of the board as true to the original design as possible (for $$ reasons). The idea of a well thought out, non PTP, approx. $100 tube amp is too much to ask for.

And thanks to MisterX for the alternate vendor suggestions. It would seem highly likely that the boards could be had for under $20 and relatively quickly.

post #20 of 589
the $40 that DIYCable.com wants seems like highway robbery
I totally agree that a $40 board is a bit much for what is supposed to be a beginner's tube project. I'm certain this turns off potential builders for that fact alone. I hope Nate's effort works out for everyone.

The idea of a well thought out, non PTP, approx. $100 tube amp is too much to ask for
It's possible. Keeping board cost at a minimum is key. The price just for the amp excluding shipping, case, psu, and minor stuff is about $75.

modify buffer locations to allow use of DIP 8 components
DIP-8 sockets give you 2 modding options without much fuss: rolling and paralleling buffers. Sijosae's P2P diamond buffer is another possibility. His layout isn't much bigger than a quarter and easily mounts on a DIP-8 socket. I have not tried it though, and my post on the subject is dead pretty much. It looks like I'm the guinea pig.

I have no real desire to try any of the more exotic mods suggested like paralleling tubes or adding diamond buffers
Diamond buffers may sound high-end, but it's just ~$5 in parts from DigiKey. Keep in mind BUF634's costs $8+ for TO-220 and $6+ for DIP-8, so I would hardly call DB's exotic. I admit 4 tubes doubles your replacement/rolling cost, but it looks fun to experiment on without the risk of being zapped by high voltages.

Perhaps we can do a PCB later on with the spiffy upgrades after it's been built and tested
I'm way past the stock board at this point. I want to have fun with Pete's amp, and a prefab just doesn't provide enough flexibility. Pete was very helpful in listing component changes in order to make the tweaks work. He also noted they look good on paper but questions whether I'll get better results. I'm looking at this as a learning exercise. If my P2P puts out even a squeek, I'm happy.

I'll let you know how it turns out. This won't happen until summer though.
post #21 of 589
I'd be interested in a board- i tried contacting DIYCable.com several times about shipping to the UK, but got no reply
post #22 of 589
I'm in as well,

have had the same problems as evo_lution, doesn't seem to want to send to the UK.
post #23 of 589
Count me in too... Go team UK!
post #24 of 589
If someone changes the board for better then I'll take one as well.
post #25 of 589
Things I'd definitely like to see:

1) DIP-8 Buffers - Both to provide the option of diamond buffers and easy buffer rolling / replacement. I think this is the most important change.

2) Off-Board Inputs, Outputs, Volume etc. - I like to do all such things off-board (esp. because I think I would probably integrate it into a pre-amp).

3) As others have already noted - the smaller it is the cheaper it will be... which is a definite plus!

4) But on the other hand, if we could avoid an ultra-tight spacing of pads (obviously this can't be done for every section of the board) it would make the board easier to newbies... and fumbly DIYers!

5) I'd also love to see someone put this together into kit form so that we can all save on shipping... plus they could probably still make a little profit and sell it for cheaper because of the economy of scale.
post #26 of 589
The BUF634 is fairly popular around here. Maybe someone should design a diamond buffer module that will drop in and replace it.

On a related note, if the board is redesigned to handle DIP8 buffers please leave a little room around the socket for a diamond buffer.
post #27 of 589
I just got an email from Pete Millett blessing this undertaking - I emailed him earlier today because I thought that since it's his original design, it would be nice to make sure that he didn't have any objections to me tearing his board apart. He even offered to put links on his webpage to whatever we eventually come up with.

What a class act...

I've spent a little bit of time going over the board and removing most of the on-board input and output components. I've also added an ALPS "Blue Velvet" volume control in parallel with the Panasonic EV-J, a la the PIMETA.

There is room on the board to use both the socketed BUF634 and a discrete diamond buffer, with a jumper to select between the two. That is an option, however there are several implementations of the circuit, so I guess that we'd have to come to an agreement over which would be best. I can also leave space around the DIP8 part so that a custom board could be used. Perhaps that might be a project to run in parallel with this one instead of putting too many options onto the main PCB. I'd be happy to work out space requirements on the main PCB if somebody wants to work on an off-board diamond buffer.

Peter's web site discusses the features of the board. Please speak up if there is more (or less) that you'd like to see on the board and I'll see what can be done to accomodate everything. Nate and I agree that there's no big rush on this - I don't think that he has any deadline in mind yet, so please let your creative juices flow!

post #28 of 589
Thread Starter 
An updated board is already forming, I've already seen a preview . Drew and I are currently working on the the basic list of mods and are exploring the idea of having both buffer types on board with a jumper to switch between the two. We'll see how that shakes out.

I don't think there is any great need to compress the board down super tight. Reducing the board size some will happen by default in removal of all the board mounted components. How much we persue reduction beyond this point is a yet to be determined quantity.

So stay tuned, I expect that we'll have a layout for review in the next couple of days. Seeing as Drew is voluteering his time and effort to do this there's no way I'm going to pressure him at all .

post #29 of 589
Thread Starter 
Evidently Drew beat me to the reply above hehehe.

I also spoke with Peter to get the go-ahead with this project and have to agree with Drew, absolute class act.
post #30 of 589
Will a diamond buffer be absolutely necessary? Modifying another circuit are you absolutely sure you can guarantee stability?..Which would require extensive prototype testing..

Diamond buffers designed from scratch to fit a specific circuit run into stability problem - is there such a thing "universal diamond buffer" out there? I maybe wrong, but I was under the impression that diamond buffers were very sensitive to the components around it..
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