[Squalish]

Since the group-buy thread got closed(turned into a for-proft, I think), I'd like to start a new thread to discuss the sijosae mint-gilmore PCB and its possible implementations.

Summary: We were musing on a Gilmore PSU and a Gilmore battery pack in modular mint tins. The transformer alone seems to be larger than a mint tin, but if we were to get an unregulated wallwart and put the other components into a mint-tin, it might fit. An RC battpack or two in a mint tin looks like a good portable source.

 

[Whit]

Maybe something like a Jung-Didden regulator? How could we fit the smoothing caps? A smaller Gilmore power supply definitely seems possible but fitting any "real" power supply in an altoids tin seems near impossible.

 

[martioz]

To feet "full size" KG into mint box you need to go into SMT, but in this case you still need kind of energy source like batt pack or unregulated "wall-bug".
I would vote for the external battery pack since is easy to control and gives you more flexibility (main is not really portable). To reduce size we should go into Li batteries (Is rechargeable LI-S available?), otherwise you will have to carry quite a lot of weight.
By the way what is SMT replacement for transistors use in KG?

 

[Squalish]

Quote:

Originally posted by martioz To feet "full size" KG into mint box you need to go into SMT, but in this case you still need kind of energy source like batt pack or unregulated "wall-bug". I would vote for the external battery pack since is easy to control and gives you more flexibility (main is not really portable). To reduce size we should go into Li batteries (Is rechargeable LI-S available?), otherwise you will have to carry quite a lot of weight. By the way what is SMT replacement for transistors use in KG?

Sijosae made a KG in a mint tin. His layout of KG's design was made into an expressPCB file by subsonic, with plans for a group buy. Making the PSU was at issue. The idea was that it could be made with a short-life battery pack in a mint tin, with interchangeable connectors to a mint-tin PSU, so when you get home from work you just unplug the battpack and plug in the PSU. The transformer seems to have no chance of fitting in a mint tin, however, it can be replaced by an unregulated wallwart, with the regulation components in a mint tin.

I believe that this thread will be redundant when jude edits the group-buy thread for commercial content.

 

[Maxvla]

subsonic:

do you have any plans for making a psu pcb as well?

wouldn't it make sense (for the group buy) to get both boards since we have such high volume?

the pcb for the psu looks to be a bit simpler so the cost should be slightly less than the amp board.

 

[Subsonic]

At the moment, I don't have any plans on producing a pcb for the power supply. The size of the caps, transformer, heatsinks, etc... would make the pcb way too big for portable use.

 

[Maxvla]

Quote:

Originally posted by Subsonic At the moment, I don't have any plans on producing a pcb for the power supply. The size of the caps, transformer, heatsinks, etc... would make the pcb way too big for portable use.

i'm not asking for it to be portable.

i just need a board

 

[Voodoochile]

Maxvla- Antness has Gilmore PSU boards available today.

 

[tangent]

Quote:

wouldn't it make sense to get both boards since we have such high volume?

The power supply is independent from the amp board, when it comes to "volume". 100 each of two different boards isn't as cheap as 200 of a single board.

The only reason to rush ahead on a power supply board is to save people paying two shipping charges, and having to change from a working power supply to a new one when the new boards are ready.

I looked into DC-DC converters, and it's not that wonderful a situation:

Cosel ZUW102412: 18-36V in, +/-12V 450 mA out. $46.62 This one is good for 2x 9V rechargeable batteries, like the Plainviews.

Cosel ZUW100512: 4.5-9V in, +/-12V 350 mA out. $46.62 This one is good for 4x 1.2V rechargeable cells.

Here's what a board with this converter could look like, using AAA's:

You'd have to use metal battery holders to get that many batteries on the board -- plastic holders are too bulky. I haven't actually checked if you can pull this off yet, so maybe even metal holders are too big. The same board will allow enough room for 2x9V, if you don't use battery holders. 9V's are snug enough in a mint tin that you don't need battery holders.

I should point out that only the AAA version would really need a board. For the 9V version, you could just glue the DC-DC converter upside down in the mint tin and give the batteries the remaining space.

With the first setup (2x9V Plainviews, 170 mAh), you get about 20V in and +/-12V out, and plenty of current. Since there's a 1.2x voltage gain and a 81% efficiency, you can expect a 400 mA output to require something like 600 mA input. Two Plainviews can hack that okay. But I wonder how useful this is relative to just a pair of 9V batteries driving the load directly. There's a bit of voltage gain here, which may be helpful, but there's a fair bit of power loss. Battery life effectively goes to about 225 mAh (down from 340 mAh) with these losses in effect. The question is, is the voltage gain worth this loss?

With the second setup (4xAAA, 750 mAh), 4.8 to 5.6V input gets transformed to +/-12V out. Current output is lower with this setup, but apparently at lower voltages the KGCA doesn't need 450 mA. To get all 350 mA out of this converter, you need to put about 2.25A in. That's a pretty heavy load for 750 mAh batteries -- it's really right at their outer limits. ("3C") This isn't that great, either.

I dunno, the battery idea isn't looking that great to me, except as a curiosity. And, going the board-less 9V route is a lot cheaper and may actually work better.


Okay, I've shot the battery idea down.

EDIT: ...and Subsonic just shot the wall supply idea down. I guess that settles it.

 

[Maxvla]

Quote:

Originally posted by Voodoochile Maxvla- Antness has Gilmore PSU boards available today.

yeah i see he has them for 35 bucks.

i figured since we got our amp board from 33 bucks a piece to 5 bucks a piece it would make sense to devise our own board and save some money. or is it wrong to do that?

 

[Maxvla]

Quote:

Originally posted by tangent The power supply is independent from the amp board, when it comes to "volume". 100 each of two different boards isn't as cheap as 200 of a single board. The only reason to rush ahead on a power supply board is to save people paying two shipping charges, and having to change from a working power supply to a new one when the new boards are ready.

i understand its 100 of 2 boards.. but you are still getting the 100 discount on two boards. still a significant savings.

there's no rush i can see from anyone who posted in that other thread. he could take his time making the psu board then getting prototypes for each and making sure they work.

edit: i've put up a temporary ezboard for discussion of the group buy. the discussion on headfi is purely design. here's the link to the ezboard: http://pub21.ezboard.com/fgilmorehea...picID=12.topic

 

[tangent]

Quote:

i figured since we got our amp board from 33 bucks a piece to 5 bucks a piece it would make sense to devise our own board and save some money. or is it wrong to do that?

Yeah, it's wrong to do that, and probably somewhat pointless, too. Competition between different designs -- even different sizes of the same basic design, like the META42 vs the Fixup Super Mini -- is a good thing, but just making a direct competitor splits the market. Splitting a small market means one guy probably goes out of business. I dunno, $35 might be a bit high for a full-size Gilmore board, but it's not a big enough deal to be worth the hate and discontent you'd cause by trying to put Antness out of business. High-end audio is too small a world to tolerate cut-throat business tactics.

Besides which, you've got to remember that Antness' boards are something like 4x the board area as Subsonic's little mint tin board. Board cost goes up as a function of board area. $30 might be a very good price, I dunno. And, I hope Subsonic doesn't sell these mini-KGCA boards for just $5 each. If he does, he'll probably only make one run, ever, because he'll get burned out. Just like not putting Antness out of business, we don't want to burn out willing servants like Subsonic. We'll run out of volunteers quick if we treat them like that.

 

[Maxvla]

Quote:

Originally posted by tangent Yeah, it's wrong to do that, and probably somewhat pointless, too. Competition between different designs -- even different sizes of the same basic design, like the META42 vs the Fixup Super Mini -- is a good thing, but just making a direct competitor splits the market. Splitting a small market means one guy probably goes out of business. I dunno, $35 might be a bit high for a full-size Gilmore board, but it's not a big enough deal to be worth the hate and discontent you'd cause by trying to put Antness out of business. High-end audio is too small a world to tolerate cut-throat business tactics. Besides which, you've got to remember that Antness' boards are something like 4x the board area as Subsonic's little mint tin board. Board cost goes up as a function of board area. $30 might be a very good price, I dunno. And, I hope Subsonic doesn't sell these mini-KGCA boards for just $5 each. If he does, he'll probably only make one run, ever, because he'll get burned out. Just like not putting Antness out of business, we don't want to burn out willing servants like Subsonic. We'll run out of volunteers quick if we treat them like that.

while i was typing that i was thinking about how that really is wrong to do that. i was just trying to save myself some green. :/

and you brought up a good point about the board area. i hadn't even thought about that.

better to not do a psu board. just the amp and buy the psu boards from antness. i'm don't wanna take someones design.. mass produce it like a walmart or something and put him out of business.

edit: re: 5 bucks

talking about the board cost.. not the end price. he better charge more than it costs. he should get some reinbursement for shipping out 90 boards. i sure wouldn't do it for free. i might do 5 or so but not 90.

 

[damonpip]

One way to make the PSU cheap would be to make it on the same expressPCB layout as the amp board, only problem is, everyone would have to buy both boards and cut them apart, or Subsonic would have to cut them apart

 

[Maxvla]

Quote:

Originally posted by damonpip One way to make the PSU cheap would be to make it on the same expressPCB layout as the amp board, only problem is, everyone would have to buy both boards and cut them apart, or Subsonic would have to cut them apart

doing that would make antness lose alot of potential money. basically pulling the rug right out from beneath him.

even though he charges 35 for his psu board i think we should buy it from him. the amp board subsonic is making is purposely for the smallest enclosure possible and therefore is mostly acceptable even though it is a similar (or same, i'm not that gifted to know the differences) design to the original.