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Old 7th December 2008, 03:54 PM   #11
rhysh is offline rhysh  United Kingdom
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Quote:
Originally posted by theAnonymous1
I have >100 peices of PGA2320 if anyone needs some.

rhysh, maybe we can work out a trade if you think you can put together an IR controller like mentioned above.

I will see what i can do.
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Old 7th December 2008, 07:57 PM   #12
Dr_EM is offline Dr_EM  United Kingdom
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It'd be good if through buying large quantities and possibly supplying the chips with the PCB costs could be kept down.

I mention the DIP PGA chips since there is a supplier where they can be obtained very cheaply:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...%3DI%26otn%3D1

I ordered 2 sets a fair while back but after chasing it up it appears they were lost and are being re-sent. If they do actually arrive I will be sure to let you know as that price (about 3.50 each) is pretty unbeatable I'd think. Plus DIP easier to solder or mess with on breadboards
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Old 7th December 2008, 08:07 PM   #13
rhysh is offline rhysh  United Kingdom
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Quote:
Originally posted by Dr.EM
It'd be good if through buying large quantities and possibly supplying the chips with the PCB costs could be kept down.

I mention the DIP PGA chips since there is a supplier where they can be obtained very cheaply:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...%3DI%26otn%3D1

I ordered 2 sets a fair while back but after chasing it up it appears they were lost and are being re-sent. If they do actually arrive I will be sure to let you know as that price (about 3.50 each) is pretty unbeatable I'd think. Plus DIP easier to solder or mess with on breadboards
The DIP PGA's do look cheaper, but rerember to look out for fake IC's, there are a huge amount floating around at the moment (im not trying to suggest there is anything wrong with your purchase).

I have got my mind set on using SMD for this project, i can think of 5 advantages right now.

1. Digital traces remain on one layer only unless needed (no thru holes)
2. Smaller IC size (between 30-50% of dip size), smaller board.
3. SMD resistors are 20% the size of normal resistors
4. Less noise, no leads that need trimming in the digital section etc.
5. Components can be placed on the layer below, as SMD does not cross layers.
6. No routing round parts is required on the layer below, as there are no pins or pads to avoid.

Put it this way, you can probably fit 11 of these boards on one sheet of A4 paper, if i was using DIP packages the board would be quite a lot bigger then this.

If you are intrested in boards, and you really did want to use the DIP package im sure i would be able to find a way into using it.
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Old 7th December 2008, 08:14 PM   #14
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Have you seen the similar project by fellow member error404?

http://audio.gotroot.ca/minivol/

I have a bunch of these boards and they work great. This is what I would like the IR controller for.
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Old 7th December 2008, 08:19 PM   #15
rhysh is offline rhysh  United Kingdom
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Quote:
Originally posted by theAnonymous1
Have you seen the similar project by fellow member error404?

http://audio.gotroot.ca/minivol/

I have a bunch of these boards and they work great. This is what I would like the IR controller for.

Yes, that is where i got the idea for the project, except that i wanted a input and output buffer on there. The firmware by error401 is compatible with my pcb, except that i do not offer the mute led function.

It looks like if i do get around to developing this IR controller, it will be directly compatible with your PCB, as we are working off the same microcontroller, basic schematic and firmware.
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Old 7th December 2008, 09:14 PM   #16
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Hi rhysh

I am very interested in this project, bored of messing about with expensive attenuators. So count me in for a couple of those boards if you decide to go for it.

I agree with your choice of smt components & through hole for signal path - i think you could use smt throughout to minimize signal path

I don't quite like the choice of DRV134 for balanced output, I would prefer a THS4131 in smd as well.
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Old 7th December 2008, 09:16 PM   #17
rhysh is offline rhysh  United Kingdom
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Quote:
Originally posted by chatziva
Hi rhysh

I am very interested in this project, bored of messing about with expensive attenuators. So count me in for a couple of those boards if you decide to go for it.

I agree with your choice of smt components & through hole for signal path - i think you could use smt throughout to minimize signal path

I don't quite like the choice of DRV134 for balanced output, I would prefer a THS4131 in smd as well.

Hi, thanks for the reply. The real reason i picked the drv134 is becuase i have a few to hand, and i am confident with using it. I will take a look at the THS4131 and see how easy it is to implament.

Rhys
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Old 7th December 2008, 09:36 PM   #18
Dr_EM is offline Dr_EM  United Kingdom
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Have definately considered they may be fakes, will have to check when/if they arrive. Thats some fair points on SMD though, guess I'll have to get my soldering skills up a bit

I probably wouldn't be using the balanced outs since I never made my power amplifiers balanced (might have been wise to do so though in hindsight). The chip could be bypassed and/or not installed if wanted?

Small board size is nice, especially when 3 or 4 must be installed along with active crossovers, power supplies and other bits!

Through hole resistors might be lower noise due to thier higher thermal mass? I like them anyhow
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Old 7th December 2008, 09:46 PM   #19
rhysh is offline rhysh  United Kingdom
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Quote:
Originally posted by Dr.EM
Have definately considered they may be fakes, will have to check when/if they arrive. Thats some fair points on SMD though, guess I'll have to get my soldering skills up a bit

I probably wouldn't be using the balanced outs since I never made my power amplifiers balanced (might have been wise to do so though in hindsight). The chip could be bypassed and/or not installed if wanted?

Small board size is nice, especially when 3 or 4 must be installed along with active crossovers, power supplies and other bits!

Through hole resistors might be lower noise due to thier higher thermal mass? I like them anyhow
Dr.EM,

Yes, if you are not using balanced outs you may indeed bypass those chips, that is all you need to miss out. This was intended to be an option anyway.

Basicly, i have used SMD resistors in all the digital paths to save space, and through hole resistors in all the signal paths so higher quality resistors can be used, as you can see round the input and output buffers.

The actual board size is 93x44 mm, very small and easy to fit a few in a enclosure.

SMD is not that hard to solder at all! just flood all the legs then remove the excess solder with the braid, this has been the easiest way for me! (before i bought a toaster oven from argos)

Rhys
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Old 7th December 2008, 09:49 PM   #20
rhysh is offline rhysh  United Kingdom
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I will be doing a low profile power supply to go with this board, for anyone who is intrested. (under 4cm height).
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