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

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#721
Re: Ping: Brian...

mourip said:
Hi Brian,

I am interested in purchasing an amp kit and have a couple of questions.

Do I need to do anything other than going to the web link and ordering through PayPal?

Assuming that you are still taking orders for this run, how long would it take to fill an order placed now for the basic kit?

Thanks a lot,

Paul
Click to expand...

I am still taking orders, and all you need to do is order throught my ordering page here:
http://www.briangt.com/order

As for the current status with orders, I have all the US orders shipped up received before the 21st, and half of the international orders. I am currently waiting for more parts to arrive on Monday, then I will ship the rest of the orders out. New orders placed now should be shipped out by the end of next week.

--
Brian
 
#723
Premium kit!!

Hey Brian-

Please put me down for one of the premium kits since they are still showing as back order on the website.


I have one of each of the three toids from Steve @ Apex on their way so I can try the amp with all three voltages.

Thank in advance,

Troy
 
#724
power needed

if i wanted to build a dual-mono setup and i assumed a 90 db sensitivity speaker, what size power transformers do i need?

also, does anyone have a conceptual list of parts need to build a dual-mono integrated amp setup?

thanks,
kevin
 
#725
planet10 said:


I'm familiar with that technique... sometimes i just pretend i have 3 hands too.

Some hemeostats & a little vise sure come in handy

dave
Click to expand...

Uh, guys, don't use your mouth to feed solder! Remember it's an alloy of LEAD and Tin... and Lead is toxic.

You probably want to not eat, smoke, stick your fingers in your mouth, eyes or other places.. till you've washed your hands after handling solder.. Rub some on paper, you'll see it works almost like a pencil. Rubs off on things easy.

Dosen't poison you right away.. but it's cumulative, and a little adds up over time. Safe levels in water and such are in the parts per billion.

Something to keep in mind....

PS, I'll second small vises for holding boards. Panavise makes some great stuff.. costs a bit but is a good investment if you get into kit building. This one is so simple you hardly need it, but for something with more parts it's worth a lot...
 
#726
I shipped out half of the existing international orders, and the rest should go out tommorrow, along with the rest of the domestic orders (might have to get some of the domestic orders out on thursday).

I am still accepting orders for basic kits, pcbs and monoblock upgrades. I will not be taking orders for premium kits until I have the components in hand, which still might take some time, as it is hard to obtain the exotic resistors. I am hoping to be able to take new orders within 2 weeks, depending on the suppliers.

Order page:
http://www.BrianGT.com/order/
no need to worry about the Wiki

--
Brian
 
#727
Brian:

I am in the process of building my second NIGC from your 3875 kits and now would like to construct something with a little more umph. Here are some questions ... Should I consider building a bridged 3875 or wait for the parallel 4780? What is the anticipated wattage of each unit?

In fact, I'll take anybody's considered opinion.
 
#728
chipco3434 said:
Brian:

I am in the process of building my second NIGC from your 3875 kits and now would like to construct something with a little more umph. Here are some questions ... Should I consider building a bridged 3875 or wait for the parallel 4780? What is the anticipated wattage of each unit?

In fact, I'll take anybody's considered opinion.
Click to expand...

It will take a 3 weeks to a month for the parallel 4780 to become a reality, as I am getting prototypes done at the end of this week, which take a week to get back, then they need to be tested and production boards made, which take a week. Then with all shipping and parts ordering, it will probably take a 3 weeks to a month before people receive the first orders.

If your speakers are 4 ohms, you can parallel 2 channels of the current LM3875 boards. It is recommended that you put a 0.22ohm resistor in series with the output before summing. It should give you about double the power. (each amplifier is seeing twice the load when paralleled)

If your speakers are 8 ohms, you could bridge them together with a DRV134 chip, or a simplier bridging circuit. The same goes for the output resistor. The power output will be about double also. (each amplifier sees 1/2 the load when bridged)

I am eventually going to make a bridgeclone with my boards, aiming for 200w with 6 boards, bridged with 3 paralleled boards per side. I have all the parts matched for this, and everything ready to go, but just haven't made it into lab yet... hopefully details will be posted soon.

--
Brian
 
#730
chipco3434 said:
From the ordering side, what would be the BOM for a 200W bridgeclone version.
Click to expand...

We will see how it goes with mine. Here is my BOM so far:

1 - 1000uF 4x25vac transformer with faraday shield between primary and secondary windings (was supposed to be for my aleph)
6 - basic kits (12 channels and 2 power supply boards)
12 - 0.22 mills 3w 1% MRA resistors (Dale 1% 3W from mouser would be probably as good)
2 - DRV134 chips with decoupling capacitors
2 - protoboards for DRV134 chips
4 - terminal blocks for power supply boards outputs (so you can use 6 channels one one power supply board
2 - moderate sized heatsinks (also from a planned aleph)
some thick solid copper wiring for tying the parallel outputs to (3 parallel channels per output)
various size slow blow fuses to determine the needed size

I posted a bit in this thread with pictures of my transformer and heatsink:
http://www.diyaudio.com/forums/showthread.php?postid=352209#post352209

Hopefully I will complete my prototype for this monster soon, then possibly put together a variation of the kit for it.

The lm4780 would be good for a bridgeclone. I would probably use 4 of them per channel, looking to product 300W or so. Two of them per channel could product 150-200w per channel bridged.

--
Brian
 
#733
yuval said:


did you send it FIFO ?
Click to expand...

I kept it mostly FIFO. Your order has been shipped out.

All international orders have now been shipped out, except for 2 of them, which use the LM3875T. I am unable to find the insulated bushings to go along with the insulators, so I will go try to pick some up locally, and mail them out tommorrow.

I have started mailing out the recent domestic (US) orders. US orders should have received a tracking number, from when I printed out the postage for the orders. I should be able to get the rest of the domestic orders shipped out tommorrow.

All new orders should be shipped out within a week, as I have all the parts for them now. I am still accepting orders for everything except for the premium kits:
http://www.BrianGT.com/order

Hopefully I will get the premium resistors soon.

--
Brian
 
#736
jaume said:
Brian I'm waiting for two basic kits. I'll use to make a 2-way active speakers.

Perhaps I'll build a premium kit for the highs. If so, is there an easy way to bridge these kits in the current form?

Thank you.
Click to expand...

Your kits have shipped out yesterday, or the day before.

For bridging, it should be possible to bridge 2 LM3875 boards, with the addition of an output resistor on each to sum the output.

You will need to create a circuit to bridge the two boards, with opamps, discrete components, or a differential driver chip like the DRV134.

I should also have LM4780 kits out in a month or so, which will be essentially 2 paralleled gainclones, providing more power.

--
Brian
 
#739
Full schematic with DRV134 (from the document linked above):
 

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