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Group order of non-inverted LM3875 pc boards? Anyone interested?

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Re: My condolences for GT

JazzzSpazzz said:
I just wanted to give Brian & his new wife my congratulations on their marriage and pass on the Brian my condolences on GTs loss to UConn. Pretty much everyone here in CT is charged up for the women's game tonight--double champions would be really cool. If it makes you feel any better, Brian, the Univ I work at will probably never send a basketball team to the sweet 16, ever!

I also wanted to mention, I got my stuff last week in great shape (Thanks again, Brian) and I just picked up a 120 + 120 / 25 + 25 Avel Lindberg toroidal tranny at their headquarters in New Milford yesterday. Really nice people. Check out their web page if you are interested. They do not have any problem selling & mailing 1 tranny out--but these trannys are heavy!

I think I've settled an a design & as soon as I finish my taxes (& watch the UConn women's game), I'll get building.

Cheers & thanks again,
Bret Morrow

Thanks, it was a sad loss in the final game, but it is great that they made it that far. I would imagine that it would be crazy in CT if the women win tonight!

What did you pay for the Avel transformer directly from them?

Good luck with yours project

--
Brian
 
Quality of Avel

I had put in an order with John at Victoria Magnetics, then canceled because I was thinking of going with dual transformers. Because VM is working on a 10-14 day lead time, I got impatient and ordered a pair of Avel 2x25 250VA from Parts Express. When I got them I was kind of disapointed in the quality, they arent wound as neat the the input/output wires seemed cheap.

I then flip-flopped back to a single power supply (after concerns that I wouldn't be able to match the power supply voltages between the 2 supplies and I've read that voltage regulators may not be a good idea with the GC) I ordered a 2x26 520VA from VM with taps at 2x20. That way I can run 28v rails for 4 ohm loads and 36v rails for 8 ohm loads. And I have 4 Panasonic 12v 7.2ah SLA batteries on the way to try battey power.

Am I just being too anal about the Avel transformers? Should I just keep them for some standard grade GCs? Anyone else with any thoughts on the quality of other manufacturers?

David
 
Re: Quality of Avel

net-david said:
I had put in an order with John at Victoria Magnetics, then canceled because I was thinking of going with dual transformers. Because VM is working on a 10-14 day lead time, I got impatient and ordered a pair of Avel 2x25 250VA from Parts Express. When I got them I was kind of disapointed in the quality, they arent wound as neat the the input/output wires seemed cheap.

I then flip-flopped back to a single power supply (after concerns that I wouldn't be able to match the power supply voltages between the 2 supplies and I've read that voltage regulators may not be a good idea with the GC) I ordered a 2x26 520VA from VM with taps at 2x20. That way I can run 28v rails for 4 ohm loads and 36v rails for 8 ohm loads. And I have 4 Panasonic 12v 7.2ah SLA batteries on the way to try battey power.

Am I just being too anal about the Avel transformers? Should I just keep them for some standard grade GCs? Anyone else with any thoughts on the quality of other manufacturers?

David

I have gotten most of my transformers from John at VM, and every one of them has been great quality.

I have seen a Plitron transformer before, and it looked nice also.

--
Brian
 
Re: Re: My condolences for GT

BrianGT said:


Thanks, it was a sad loss in the final game, but it is great that they made it that far. I would imagine that it would be crazy in CT if the women win tonight!

What did you pay for the Avel transformer directly from them?

Good luck with yours project

--
Brian

Wow, talk about wild. This is the only time both the men & women from the same university won both championships the same year. GT has a lot to proud about--they had a great season.

I paid $38.42 USD picked up in New Milford, CT. I got the D4040, 230VA 25+25--this one has solid leads rather than braided. They were out of the braided one. The woman who handles the orders knew what I was going to use it for and even heard of gainclones. It was a nice drive for me--1 funny thing: in New Milford there is a very old graveyard with a very old sign "gallows hill cemetary". I'm not kidding--I nearly drove the car off the road looking at the sign Wild, wild west (of Connecticut)!!

Cheers,
Bret Morrow
 
Re: Re: Re: My condolences for GT

JazzzSpazzz said:


Wow, talk about wild. This is the only time both the men & women from the same university won both championships the same year. GT has a lot to proud about--they had a great season.

I paid $38.42 USD picked up in New Milford, CT. I got the D4040, 230VA 25+25--this one has solid leads rather than braided. They were out of the braided one. The woman who handles the orders knew what I was going to use it for and even heard of gainclones. It was a nice drive for me--1 funny thing: in New Milford there is a very old graveyard with a very old sign "gallows hill cemetary". I'm not kidding--I nearly drove the car off the road looking at the sign Wild, wild west (of Connecticut)!!

Cheers,
Bret Morrow

LOL! Gallows hill cemetary? Must have had a few witch hunts up there in Connecticut, too. How many "resisdents" does it have?
 
Re: Re: Re: My condolences for GT

JazzzSpazzz said:


Wow, talk about wild. This is the only time both the men & women from the same university won both championships the same year. GT has a lot to proud about--they had a great season.

I paid $38.42 USD picked up in New Milford, CT. I got the D4040, 230VA 25+25--this one has solid leads rather than braided. They were out of the braided one. The woman who handles the orders knew what I was going to use it for and even heard of gainclones. It was a nice drive for me--1 funny thing: in New Milford there is a very old graveyard with a very old sign "gallows hill cemetary". I'm not kidding--I nearly drove the car off the road looking at the sign Wild, wild west (of Connecticut)!!

Cheers,
Bret Morrow

That is totally insane. I can't imagine what it must be like in CT now. I have seen some rioting videos on the news.

What gauge solid wire do they put on their transformers?

heh.. strange sign 😉

--
Brian
 
Re: Re: Re: Re: My condolences for GT

BrianGT said:


That is totally insane. I can't imagine what it must be like in CT now. I have seen some rioting videos on the news.

What gauge solid wire do they put on their transformers?

heh.. strange sign 😉

--
Brian


Actually, its a lot less mayhem than the last time the men won. Its a shame that some idiots feel the need to behave like that. UConn has always had some problems with bored white kids from the 'burbs "acting out". Women's basketball on its own rarely results any violence--it also usually has a much bigger following.

With regards to the gauge, I add a note when I get home & can check, but the power in lines look fairly thin to me. The secondaries are more robust. I guess that the primaries are 19-20 ga. & the secondaries are about 16-18 ga. I drop an email in tonight with more accurate measures.

Cheers,
Bret Morrow
 
Re: Re: Re: Re: My condolences for GT

tpenguin said:


LOL! Gallows hill cemetary? Must have had a few witch hunts up there in Connecticut, too. How many "resisdents" does it have?

It was just a small old New England cemetary. It looked like about 50 graves or so. Cast iron fence--to keep people out because they are......dying to get in there 😀 (Sorry!) I am guessing that it has graves from Colonial times or early 1800's, but I didn't stop to look. "Only" 4 documented "witches" killed here in CT ~1650's and none in New Milford. Not enough to fill a cemetary, anyways. Killing people as witches was something that those nuts in Mass really excelled at! 😉 (Sorry again!)

Cheers,
Bret Morrow
 
grimberg said:
BrianGT,

I sent you an e-mail through the forum yesterday. Have you received it? I just want to make sure your e-mail address is current.

I have quite a few e-mail in my box now that I haven't answered yet, as I am just starting to get over a cold that I have had for the last week. I will catch up soon and answer all the mail in my box.

--
Brian
 
The Caddock resistors in the kit I received a couple of days ago are of a slightly different value. probably due to availability.

No problem, of course.

But I wonder what the effect of that slightly lower value will be?

The 4 Caddocks are different , 19.8k.
That means the feedback is different and the over all ratio will be 19.8k/620.

How is the chip going to react, sonically?
Will I have an even better amp?

I hope so...

Marc
 
zeno said:
The Caddock resistors in the kit I received a couple of days ago are of a slightly different value. probably due to availability.

No problem, of course.

But I wonder what the effect of that slightly lower value will be?

The 4 Caddocks are different , 19.8k.
That means the feedback is different and the over all ratio will be 19.8k/620.

How is the chip going to react, sonically?
Will I have an even better amp?

I hope so...

Marc

620 ohms / 20k (19.8k) is almost the same exact ratio as 680 ohm / 22k. Sonically, there should be no difference. This is clearly a result of availability. I had to buy out the stock of Caddock resistors from 6 different vendors to get enough for the kits.

If you calculate the gain by the equation Av=1+Rf/R3, you will see that 1+22k/680k = 33.35, and 1+20k/620 = 33.25. In your case, 1+19.8k/620 = 32.9. A gain of around 30-33 seems to work good in the given gainclone configuration, which is what the kits have been put together with.

--
Brian
 
Re: Wire gauge for Avel Lindberg Tranny

JazzzSpazzz said:



(SNIP) With regards to the gauge, I add a note when I get home & can check, but the power in lines look fairly thin to me. The secondaries are more robust. I guess that the primaries are 19-20 ga. & the secondaries are about 16-18 ga. I'll drop an email in tonight with more accurate measures.

Cheers,
Bret Morrow

Hey Brian,

Weellll, I got home and took a look and realized that I'd need a micrometer to get an accurate measure. Of course, I have 1 at work.....🙄

I would re-guess that the primaries are a little thicker than I guessed yesterday, maybe 18 ga. and the secondaries are 15-16 ga. If you need to know exactly, tell me & I can bring the micrometer home & measure them. I'm out of the office tomorrow and visiting family for the weekend, so I couldn't get back to you until next Monday. Drop me an email & I measure them for you.

Sorry,
Bret Morrow
 
Back by popular demand:

I have started taking orders again for NIGC (non-inverted gainclone) basic kits and pcbs. I put a new order page up on my website at:
http://www.BrianGT.com/order
Be sure to add the appropiate shipping to your cart before checking out.

I am only offering Basic kits and PCB sets at this time. I have ordered the parts for the premium kits, and am expecting them in a few weeks. Basic kits are selling for $35, and pcb sets are selling for $15. I am keeping the prices at a reasonable level, and a portion of the profits will be donated to diyAudio.

I will start shipping out the new orders out at the end of next week.

The premium kits will be offered again in the near future, as soon as I receive the parts for them. I won't be accepting any payment for the premium kits until then. (expecting 2-5 weeks, according to manufacturer's lead-times)

Here is a link to my gallery of projects using my kits/pcbs:
http://www.briangt.com/gallery/nigc
and build pictures from my amplifier using the kit:
http://www.briangt.com/gallery/nigc-kit

The Wiki here also has information on the kits:
http://www.diyaudio.com/wiki/index.php?page=NI+GC+PCB+Group+Order+Phase+II

Drop me an e-mail, or make a post here if you have any questions.

--
Brian
 
Now offering Dual Monoblock upgrade for kits

By popular request, I am now offering a monoblock upgrade for the kit, consisting of a pcb set, 8 - MUR860 diodes, and 2 - 4.7uF capacitors. This will allow you to add an extra power supply unit to your kit to run a dual monoblock setup.

The pricing is:
$18 for the upgrade with 4.7uF Panasonic FC capacitors
$24 for the upgrade with 4.7uF Blackgate N capacitors

The ordering page is here:
http://www.BrianGT.com/order

Drop me an e-mail, or make a post in this thread if you have any questions.

Note: I am unable to offer just the power supply pcb, since the pcb set is combined on a single pcb, with scoring to easily break them apart.
Picture of pcb set:
http://www.briangt.com/gallery/nigc-kit/build001

--
Brian
 
Speaking of dual mono this will be the way that I'll have to go the transformer's that i have on hand are not large enough to power a stereo gainclone 22volts @ 130va I already have three sets of yor boards.Could you post the proper way to wire up the supplies to the rectifier and in turn to the Amp boards.Almost failed to mention these have dual secondaries or four output wires
 
jhead said:
Speaking of dual mono this will be the way that I'll have to go the transformer's that i have on hand are not large enough to power a stereo gainclone 22volts @ 130va I already have three sets of yor boards.Could you post the proper way to wire up the supplies to the rectifier and in turn to the Amp boards.Almost failed to mention these have dual secondaries or four output wires

Jack,

The manual should go over how to wire up the kit with a transformer with dual secondaries, which is the standard way to put together the amplifier.

If I am misunderstanding your question, drop me an e-mail and I will try again to answer your question.

The manual is on my website at:
http://www.BrianGT.com

--
Brian
 
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