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Old 14th May 2008, 12:46 PM   #1051
Coulomb is offline Coulomb  England
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Am I missing something? Why not order Brian's PSU boards for the MiniA's??

Anthony
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Old 14th May 2008, 01:45 PM   #1052
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Default Re: Re: Re: Mini Aleph Power Supply

Quote:
Originally posted by cfcubed


Ha ha... And YOU should locate the POWER SUPPLY BOM he asked about in those XLS downloads you referred him to... Especially prior to slamming him I only see Amp board BOMs in them...

You are ABSOLUTELY CORRECT. I totally missed the words "power supply".

Probably because if you have to ask for a power supply BOM you need to be reading more about electronics and not BUILDING anything yet.

We're not talking a regulated supply here, we are talking diodes, caps and in this case the option of resistors.


So as I will apologize for missing the intent of the original question, it just highlights how much more research needs to be done by someone who posts such a question. Mains AC can kill. In some cases just burn down the house. Either way only those who are well read and READY to work with electricity should be building devices. A pwr supply BOM is pretty elementary, and as mentioned, BrianGT has the PSU PCB's he designed when he did these Mini-A PCB's.

And it was never intended to be a slam.
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Old 14th May 2008, 03:04 PM   #1053
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Default Re: Re: Re: Re: Mini Aleph Power Supply

Quote:
Originally posted by troystg


You are ABSOLUTELY CORRECT. I totally missed the words "power supply".

Probably because if you have to ask for a power supply BOM you need to be reading more about electronics and not BUILDING anything yet.

We're not talking a regulated supply here, we are talking diodes, caps and in this case the option of resistors.

So as I will apologize for missing the intent of the original question, it just highlights how much more research needs to be done by someone who posts such a question. Mains AC can kill. In some cases just burn down the house. Either way only those who are well read and READY to work with electricity should be building devices. A pwr supply BOM is pretty elementary, and as mentioned, BrianGT has the PSU PCB's he designed when he did these Mini-A PCB's.

And it was never intended to be a slam.
Geez, lighten up man... I did put smileys in my reply after all.

In my builds w/aquired PCBs there was always a place to get a baseline BOM at least, even for PS board/section.

"We're not talking a regulated supply here, we are talking diodes, caps and in this case the option of resistors"

Guess so, but even using Brian's PS board as shown here there are options & one place you wouldn't want a noob playing around is in a PS board w/options, etc. unknown to him.

Would think it more constructive to point to some concrete information (e.g. just what should R1, etc. be - value & wattage).

Whatever, maybe BrianGT or someone else will do that...

Later.
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Old 14th May 2008, 09:32 PM   #1054
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Default Re: Mini Aleph Power Supply

Quote:
Originally posted by camarillo
Hi,
I am a new user. Excuse me for my English. I have ordered the MiniAleph pcbs to Briangt.
Where can I find the parts list of the power supply?
The site of Briangt addresses me to diyamps.com, but I don't succeed in connecting me.

Thanks.
Alright, lets get back on track.

My diyamps.com website is no longer available, as the server crashed that it was hosted.

As for the boards, they are very simple. Here is a component listing:

LED circuit:
R20 - 10k resistor
LED - I used a blue LED here
D5 - 1N400X diode (I used a 1N4004)
C9 - 10uF 50v (the value isn't terribly important)

PSU Circuit
D1-D4 - standard bridge rectifier setup, 2-pin TO-220 diodes are used here. I used MUR860 diodes, as I had them on had from the chipamp stuff.
C1-C2 - optional decoupling capacitors (0.1uF)
C2-C8 - the footprint should fit most snap-in capacitors. I used 10,000uF capacitors, as that was what I had on hand. I used 22,000uF caps for the Aleph30 project.
R1,R2 - bleeder resistors, I choose 2.2k for here
R4-R12 - these are for an optional R in a CCRC filter. If you aren't using these, install a a jumper across the terminals. I provided pads that should support up to 10-12ga wire for this. Otherwise, calculate what you need for a CCRC filter, and calculate what parallel combination of resistors you need to obtain this.

Transformer wiring
The connections for the transformer secondaries are labelled as:
AC0 and AC0(bar), and AC1 and AC1(bar). You can also use a centertapped transformer, connecting the center-tap to either AC0(bar) or AC1 (they are both tied to the ground plane).

I don't have schematic for this, but the circuit is just about as simple as you can get. I will still see if I can dig one up from my old computer, which is currently in storage.

Let me know if you have any more questions,

--
Brian
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Old 14th May 2008, 10:17 PM   #1055
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Default Re: Re: Re: Re: Mini Aleph Power Supply

Quote:
Originally posted by troystg



You are ABSOLUTELY CORRECT. I totally missed the words "power supply".

Probably because if you have to ask for a power supply BOM you need to be reading more about electronics and not BUILDING anything yet.

We're not talking a regulated supply here, we are talking diodes, caps and in this case the option of resistors.


So as I will apologize for missing the intent of the original question, it just highlights how much more research needs to be done by someone who posts such a question. Mains AC can kill. In some cases just burn down the house. Either way only those who are well read and READY to work with electricity should be building devices. A pwr supply BOM is pretty elementary, and as mentioned, BrianGT has the PSU PCB's he designed when he did these Mini-A PCB's.

And it was never intended to be a slam.

This is my first diy amp and I thought to start from a tested project how beginning of learning (diyaudio is a mine of information). I know the dangers of the mains Ac ,I have some practice in solder and I know how to use a tester. I thought that the apparently simple Mini Aleph (ready pcb and list of parts ) could be a first diy-amp of quality. Today I have seen the new thread Commercial Gainclone kit- building instructions of Peter Daniel.
It will not play like a Mini Aleph but sure I don't burn down the house.

Thanks cfcubed for your support and Thanks troystg for your warnings.

PS : however I don't surrender
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Old 15th May 2008, 12:21 AM   #1056
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Quote:
PS : however I don't surrender
Welcome to the forum.

You'll do fine
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Old 15th May 2008, 02:49 AM   #1057
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Default Re: Re: Mini Aleph Power Supply

Quote:
Originally posted by BrianGT
As for the boards, they are very simple. Here is a component listing:
<snip>
Thanks for that info Brian & thanks for making the boards available again..
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Old 15th May 2008, 08:13 AM   #1058
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Default Mini Aleph Power Supply

Thanks Brian
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Old 15th May 2008, 11:18 PM   #1059
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Is the correct schematic Brian?
Attached Files
File Type: pdf minialeph-sch.pdf (27.0 KB, 376 views)
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Old 15th May 2008, 11:23 PM   #1060
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Quote:
Originally posted by Coulomb
Is the correct schematic Brian?
It appears to be.
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Old 13th June 2008, 05:18 PM   #1061
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Default Owe troystg an apology & mini-A guys thanks

Yeah, I shouldn't have jumped all over troystg cause 1) it was a simple mistake & 2) BrianGT's PS PCB BOM is pretty much dead simple.
And any PS BOM is full of variables (xfmr secondaries, what builder is shooting for, filtering, LED brightness, etc.) See? At least I *think* I'm learning

Anyway, wanted to show my absolute noob & mostly cheapo mini-A build.

Click the image to open in full size.

It's alive! And working very well I might add. Notes:
- Yeah, spare cheap fleabay mis-matched heatsinks add to the uniqueness
- that's the fleabay 16-0-16 300VA that should have been the 15-0-15 200VA. As is 21V .8A draw X 2 per side & I can still hold the sinks for 5-10 secs after an hour & is about as far as one should push those 2 devices I'd think.
- that's a SOHA headamp w/12-sec output delay relay acting as a preamp... And it's making a darn nice one IMO so far.
- MOSFETs matched from tech-diy made 1 less thing to worry about (DC offset quickly drops to < 15 mv).


Click the image to open in full size.

Empty case ready for boards, holes & filing/sanding.
- .12 plates cut w/80-tooth non-ferrous blade on table saw
- yes, I used a very lite coat of high temp grill paint to make the mismatched HS a little more matched.

Good stuff & might be done this weekend...
Thanks again to Mr. Pass, Brian & others involved.
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Old 15th June 2008, 01:27 AM   #1062
troystg is offline troystg  United States
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No appologies needed, and congratulations on your build!

Yes, we should all be thankful to Mr. Pass, Mr. Grey and BrianGT. All VERY fine gentlemen. The world is a better place with them in it.
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Old 16th June 2008, 12:02 PM   #1063
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Quote:
Originally posted by troystg
No appologies needed, and congratulations on your build!
Thanks! Yep, got it done yesterday... Sounding good & temporarily using Radii pre
Click the image to open in full size.

Quote:
Originally posted by troystg
Yes, we should all be thankful to Mr. Pass, Mr. Grey and BrianGT. All VERY fine gentlemen. The world is a better place with them in it.
YES, if naming names to thank, mustn't leave out Grey (GRollins)!
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Old 25th June 2008, 09:16 PM   #1064
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Good morning,

I exchange 2 original mini aleph PCB circuits from Brian GT against a original power circuit PCB from Brian GT

thank you
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Old 26th June 2008, 02:18 AM   #1065
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Congrats! Looks good!
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Old 8th July 2008, 04:08 PM   #1066
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Default Couple more tidbits I've learned...

Me being new to Class A SS, I've made a couple noob discoveries & changes... So this is for other noobs & maybe as entertainment for seasoned builders

> my "As is 21V .8A draw X 2 per side.." Yeah, that's not really ideal for these output devices. Should draw at least 1A so I raised R13 to about 150k to get my build drawing 1.2A per rail per side. This got each fet to 25W idle (into the bottom of its "sweet" range from what I've read).

I used too small TO220 sinks I had on hand on the rectifiers (too hot to touch) as can be seen from this bench pic:
Click the image to open in full size.
and bought some taller solid alum ones. Although the too large transfo is not wedged against fets, its real close but amp is still dead quiet. BTW, this is a scrap build & the scrap dictated its size.

Well, even with 1/2" slots in the bottom front & back top, the thing was an oven So used screen from $1 kitchen strainer & hacked a nice, big hole in the top. Now I think its done
Click the image to open in full size.

Loved the tube pre/miniA/Hornshoppe combo... While it lasted that is. Found out the hard way that my new-to-me tube pre had nasty DC offset for a bit at turn on & turn off. It took only one out-of-order power up to fry the FE126s in my Hornshoppe horns But, Ed is coming to the rescue w/a new pair of matched & treated drivers for about the same price as the raw drivers themselves. Great guy that Ed.

Since added a full minute turn on muting delay (w/instant off) to my tube pre outs (based on a simple delay circuit).
Lessons learned for sure.
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Old 12th September 2008, 01:46 AM   #1067
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Default Matched ouput fets on A30

Hi everyone...

I am finally at the point of finishing my A30 proyect which started about 3 years ago... its been a long time. I was in the original group buy in this thread and I have the boards all stuffed only the output fets are left.

I got he parts from jasonīs kits and I have all 12 fets in matched pairs.... but only now I am thinking that I have sets of 3 fets ... so I am not really sure how to use these matched pairs.

Should it be
Pair 1 - Q8, Q9
Pari 2 - Q10, Q11
Pair 3 - Q12, Q13

or

should I have four sets of 3 matched fets, each set for Q8, 10, 12 and the other for Q9, 11, 13 ....

please advice...
thanks.
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Old 12th September 2008, 06:10 PM   #1068
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Default bump

Come on... throw me a bone here please... I have searched, I read the service manual and I dont know which way to go...
Please

thx
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Old 12th September 2008, 06:21 PM   #1069
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Seems they have to be Vgs matched.
Taken from BrianGT original part list for A30.
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Old 12th September 2008, 06:27 PM   #1070
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Default matching

The 'top' fets need to be matched to each other, and the bottom fets need to be matched to each other. Thus if you are using 6 fets per channel total, three for the current source (top) and three for the output device (bottom), you'd need two groups of three...I don't think there is anything to be gained from matching across these groups.

IIRC the input pair should be matched too.

HTH

Stuart
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Old 12th September 2008, 07:31 PM   #1071
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Default thanks

thanks guys.... that is what I thought from the same spreadsheet that korben shows, but since I got only matched pairs with my parts kit I thought I might be wrong.

So, Jason.. (jleaman) ... why was I sent matched pairs it sets of 3 are needed.... I know this is an old group buy but I would like to know from you or anyone else that was in the same buy.... maybe I am missing something here.

thanks again...
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Old 12th September 2008, 07:54 PM   #1072
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Mine were "matched" in the fact that they were ALL in the similar range.

Yes some were exactly the same but all were within a grouping.

It may be coincidental that you got pairs that were the exact, as long as you have a third just barely out..
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Old 13th September 2008, 10:47 PM   #1073
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Default Re: thanks

Quote:
Originally posted by rebojorge
thanks guys.... that is what I thought from the same spreadsheet that korben shows, but since I got only matched pairs with my parts kit I thought I might be wrong.

So, Jason.. (jleaman) ... why was I sent matched pairs it sets of 3 are needed.... I know this is an old group buy but I would like to know from you or anyone else that was in the same buy.... maybe I am missing something here.

thanks again...

I matched the FETs for Jason and I can assure you it is very problematic to match 6 devices indentically. I started with a batch size of 1000 all from the same date code, I special ordered them that way. I measured the VGS on all 1000 and then repacked them into kits for Jason. In 99% of the kits the devices were within .005 of each other. I think even Mr. pass uses a figure of .020 as an acceptable tolerance.

Can you tell me what the numbers were on the little white stickers?

Anthony
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Old 14th September 2008, 05:56 PM   #1074
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Thanks Coulomb...

I donīt have them with me right now but if I remember correctly I have

Pair - Number
1 - 400
2 - 406
3 - 408
4 - 413
5 - 419
6 - ?... canīt remember this last one but it is within this range.

Are these numbers millivolts?

thanks!
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Old 15th September 2008, 02:41 AM   #1075
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Quote:
Originally posted by rebojorge
Thanks Coulomb...

I donīt have them with me right now but if I remember correctly I have

Pair - Number
1 - 400
2 - 406
3 - 408
4 - 413
5 - 419
6 - ?... canīt remember this last one but it is within this range.

Are these numbers millivolts?

thanks!
Yes they are mV. You can easily use 123 as one side and 456 as the other IMHO.

Anthony
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