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

[Cappy]

Brian,

Thanks for the current draw results.

How efficient are your speakers? This will help me figure out the current draw with my speakers (which are 16 ohms, 99.6 db sens. by the way).

Also, do you have any idea of the current draw when the amps are plugged in but not playing music?

Bill

 

[BrianGT]

Brian,

Thanks for the current draw results.

How efficient are your speakers? This will help me figure out the current draw with my speakers (which are 16 ohms, 99.6 db sens. by the way).

Also, do you have any idea of the current draw when the amps are plugged in but not playing music?

Bill

All of my speakers are less than 90dB efficient, and I used the gainclone with both my Jordan JX92s speakers, my JBL speakers (8), my Seas Thor TL (4 ohms). My roommate ran the gainclone off a pair of big HP bench supplies, 0-50v, 3A each. At 35vdc, the current stayed quite low ( < 1A running both channels ) for low volumes. I always like to design for a factor of at least 2x the maximum current draw though, as you don't always know what to expect. I usually aim for 3x the expected. (explains the pile of 1kVa transformers sitting in my room)...

The idle current draw seems like almost nothing.

--
Brian

 

[BrianGT]

I managed to get a sizable pile of kits that will be mailed out tomorrow.

For all of those waiting for your kits, I put up the pictures from my Gainclone build, using the pcbs, which I did on Saturday. I placed all the pictures on my website:
http://brian.darg.net/gallery/nigc-kit
Captions will follow in a day or two, for all the pictures.

If it says "Bandwidth Exceeded", then it will be back up the following day, or in a few hours. I will speak to my friend, the administrator, if these problems occur, and have him raise my bandwidth.

The pictures are all sized down to 1024x768, 50% from the source photos from my digital camera (my 2+ year old Canon Pro90 IS camera). It doesn't have a macro mode, but the pictures came out fairly good.

I am still working on the users manual, and will post it to my website soon.

A couple quick notes on the pics:
-For attaching the negative feedback resistor (Rnfb), you can alternately solder it to the leads of the LM3875 coming out of the bottom of the pcb, if you do not feel comfortable doing it like I did.
-The second from the last picture is the 2 sets of boards that Meredith, my fiance, soldered, and she put the NFB resistor on the bottom pins.
-The amplifier sounds great, and better than any gainclone that I have heard thus far.
-I would recommend taking advantage of the slide show function in the Gallery software.

EDIT: captions added

--
Brian

 

[Alcaid]

Where do you ground the pot on your boards? Shouldn't the pot be connected to signal ground?

 

[BrianGT]

Where do you ground the pot on your boards? Shouldn't the pot be connected to signal ground?

For my boards, the signal goes in from the RCAs, then into the pot, then into the board. The input ground goes directly into the board signal ground. There might be confusion, because I used shielded cable in my gainclone, where you only ground one side of the shielded cable. The shield is connected to the ground rca jacks.

Let me know if there still is confusion.

--
Brian

 

[Alcaid]

So your pot is only connected to the RCA and the PCB? Shouldn't it be connected 3 places? (RCA, PCB and Signal Ground)

 

[Alcaid]

Something like this?

 

[BrianGT]

Something like this?

Here is a picture that I threw together:

--
Brian

 

[Alcaid]

Ok. Get it now. Thanks for description (Prettier drawing than mine )

 

[BrianGT]

Ok. Get it now. Thanks for description (Prettier drawing than mine )

No problem, as I had to make the drawing for the users manual anyway.

--
Brian

 

[jlh28]

Aelph transformers from VM

Brian,

Do you have the approximate dimensions of the aelph transformers that you bought from VM. I am trying to plan out my enclosure for the 6 channel GC, and I want to know about how big a space to allocate to the monster.

 

[BrianGT]

Re: Aelph transformers from VM

Brian,

Do you have the approximate dimensions of the aelph transformers that you bought from VM. I am trying to plan out my enclosure for the 6 channel GC, and I want to know about how big a space to allocate to the monster.

They are quite big If I had to guess, I would say 6" diameter, 3" tall.

I will try to remember to measure them when I get home. Drop me an e-mail, as this will help make sure that I don't forget.

--
Brian

 

[BrianGT]

Re: Re: Aelph transformers from VM

They are quite big If I had to guess, I would say 6" diameter, 3" tall.

I will try to remember to measure them when I get home. Drop me an e-mail, as this will help make sure that I don't forget.

--
Brian

I measured it finally: roughly 2.75" high x 7" diameter.

For others:
I have packed up another large bunch of orders which will be mailed out today. I will try to send e-mails out later this evening to those whose orders get shipped out. I will really try to get most of the orders shipped out this week.

--
Brian

 

[BrianGT]

Here is the large batch of orders waiting to go out today. I am packing all the components into anti-static envelopes, then into padded mailers, then Meredith will take care of labeling, placing into the priority mailers, addressing and mailing out. All the orders in the hallway should be shipped out today. I will send e-mails tonight to those whose order has been shipped out.

Most of the orders in the hallway now are for a single kit, and I will take care of more of the multiple kit orders this evening.

Please be patient with me, as I am getting the orders out as fast as I can. I am really going to try to get them all out this week.

One more thing: I have currently only been shipping out orders with the BG 4.7uF N upgrade, as I am giving a few more days for upgrade orders to come in. If you are certain that you do not need the upgrade, drop me a mail and I will ship your order out ASAP.

BG 4.7uF N upgrade page:
http://brian.darg.net/order/bg-upgrade.html

--
Brian

 

[leadbelly]

Please be patient with me, as I am getting the orders out as fast as I can. I am really going to try to get them all out this week.

Please be patient? You may not have noticed, but you're turning around this group order in record time! Relax, have a beer. And if you are actually gonna sit home and work on St. Paddy's day, for Pete's sake, have a Guiness at your side!

 

[BrianGT]

Please be patient? You may not have noticed, but you're turning around this group order in record time! Relax, have a beer. And if you are actually gonna sit home and work on St. Paddy's day, for Pete's sake, have a Guiness at your side!

Well, I am trying to set a new standard for group orders

I forgot that it was wednesday already. I guess it is definately time to get some Guiness, preferably on tap, after getting a few more orders out.


Have a good St. Patrick's day!

--
Brian

 

[Guiness]

speaking of Guiness

I am having one right now... I have to live up to my user name.
Brian is it to late for me to upgrade to Blackgate caps not sure if you shipped it or not? If not I will hook you up with the money tonight or tomorrow. I might not make it tonight though it is 10:47am and it is not looking good here in NYC...

Guiness

 

[BrianGT]

Re: speaking of Guiness

I am having one right now... I have to live up to my user name.
Brian is it to late for me to upgrade to Blackgate caps not sure if you shipped it or not? If not I will hook you up with the money tonight or tomorrow. I might not make it tonight though it is 10:47am and it is not looking good here in NYC...

Guiness

at 10:30am? You are one dedicated person.

I have not shipped any kits out yet that haven't been upgraded to use the BG 4.7uF N caps, so you can still submit the payment for your upgrade. I couldn't locate your name on the list, as it is sorted by your actual name. Drop me a mail with your name and I will see where your order is on the list.

--
Brian

 

[MereGT]

I just sent out about 13 more orders at lunch. Brian is motivating me with the potenial reward of alcohol. The "hallway" batch should be sent out before the post office closes today. I don't think the ladies working at my local post office like me very much. Thanks again for all the congrats!

Happy St. Patty's Day!

 

[Dennis Hui]

Hmmm....beer....

Three cheers for Brian and Meredith ... and happy St. Patty's Day!

Dennis