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AudioSector-chip amp kits, dacs, chassis

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Peter Daniel

Peter Daniel

Member
Joined 2002
audiosector.com
Paid Member
karma said:
peter i got the power supply finished. and im burning the amp 1 in. i find it gets really warm is this normal when u build one and burn it in? not thats it a big deal just never owned a case that gets warm all over:)
Click to expand...

When idle, LM3875 should be cold. If it runs warm, it may be oscillating.

That case gets a bit warmed up when playing music, and if you really push it, it may get quite warm, but not to any unusual levels.

DC offset doesn't have anything to do with heatsink temperature, and depending on the chip, values up to 80mV are quite normal (with minimized config).
 
W

wdavis009

Member
Joined 2005
karma said:
thanks peter. its been runing for 7 hours now and i find it is cooler
than when i first fired it up. not sure what it was but its fine now.
Click to expand...

Karma,

For what it's worth, mine too ran fairly warm the first few hours. It's been burned in for about a week and now it runs really cool.

Peter,

Tweaking the PS and switching to my TVC preamp made a big difference. Much better dynamics, bass, drive, etc. I'll try a parallel configuration next, but want to build your DAC first. Did you get my email about a DAC parts kit?

Regards,
Wade
 
Peter Daniel

Peter Daniel

Member
Joined 2002
audiosector.com
Paid Member
Hi Wade,

Got your e-mail and will reply soon. The TVC works fine with the DAC/amp combo, but I still prefer the active preamp here. Maybe because the output impedance of the DAC is rather high (about 3k) and with active preamp the dynamics and involvement factor are even better (however, coloration may be higher, and not everybody may like it).
 
W

wdavis009

Member
Joined 2005
Peter Daniel said:
The TVC works fine with the DAC/amp combo, but I still prefer the active preamp here. Maybe because the output impedance of the DAC is rather high (about 3k) and with active preamp the dynamics and involvement factor are even better (however, coloration may be higher, and not everybody may like it).
Click to expand...

I'm thinking an active preamp is the way to go with this amp also given the improvement brought about by just switching to my TVC preamp. I'm waiting to see what you come out with. ;)

BTW, right now I have replaced the 10uF electrolytics on the PS board with 100uF PIO's, and then by-passed those with .1uF PIO's. This set-up sounds really good with my Vandys. Unfortunately the four big PIO's are larger than the Plitron transformers so the Cocobolo case I just finished won't work. :smash:
 
karma

karma

Member
Joined 2003
mailed express plus the extra i .o.u from last time. for the mod

:D


thanks.
 

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rjkdivin

rjkdivin

Member
Joined 2005
Magsy said:
Have I got something on backwards in the PSU section? If I'm reading it right I have 9-10v DC after the chokes, but also 20v AC?! (2x9ac toroid)

3v of dc offset, have sound but badly distorted as you would expect.

An externally hosted image should be here but it was not working when we last tested it.


http://magsy.net/headfi/gainclone/dacbig.jpg (Bigger picture)
Click to expand...


Magsy,

Your board looks really flat on the table.....have you installed all of the components on the other side? It doesn't look like the pins for the CS8412 are sticking through the pcb from the other side or soldered?

Robert
 
M

Magsy

Member
Joined 2005
Tried two Emu 0404s and onboard SPDIF with the same effect.

It sounds like clipping, but it is not clipping according to Foobar (the player) or the soundcards control panel, levels stay well below 0db.

Running the volume -6db on the PC sorts it out though and it seems to sound ok.

I don't actually have anything standalone in the house with coax SPDIF. Tomorrow I will get a DVD player or something for testing.

I had a CS8412 + TDA1543 DAC here a few months back and that was fine with default configuration.
 
M

Magsy

Member
Joined 2005
Bought a cheap DVD player today with coax out. Playing a CD from it results in the same thing, distortion sounding much like clipping.

I've removed the input driver and bridged 6+8 and 5+7 but the sound is still the same. I've checked and double checked, resoldered the whole board but it is still the same.

The whole thing was put together using a 15w iron and considerable care, this is my 10th or so project with SMD - I am amlost certain I haven't killed something through heat.

It does leave me wondering if one of the chips is faulty but so unlikley!

Any ideas Peter? Do you have any high res pictures of a completed green board? (top down/underneath?)

Thanks:D
 
karma

karma

Member
Joined 2003
nice call. i just wanted to see if you could find the problem i had the same thing with one of my cheap dvd player with the coax out


stay away from diamond visions dvd player from walmart;)

try digital out on a another player my dac works great just not on this dvd player i get the same result that your getting

does your dvd player have digital volume on the remote?
if so turn it all the way down the coax out works with the volume
its not fixed on mine
 
M

Magsy

Member
Joined 2005
That ain't good....I'm all over this thing like mad, I can't leave it alone but it could possibly be 'normal'?

Specifically which of your players can run this DAC, with no distortion and no volume alterations?

The player I got is a supermarket own brand, but I have a pair of professional EMU 0404 soundcards, they should not be a problem.

Turning the volume down is not the answer, because you cannot attenuate a digital signal without losing bit depth...no?

Thanks for the info:)
 
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