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AudioSector-chip amp kits, dacs, chassis

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karma

karma

Member
Joined 2003
thats what the woods was for. i got it open with a light Wiggle
so far so good im just working on the pcbs. shaving half a inch off
each end to fit.;)
 

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Greg Erskine

Greg Erskine

Member
Joined 2002
Paid Member
rjkdivin said:
Nice looking layout, and nice separation from the signal path to the noisy stuff! Those look like the lower power LM3875 chips rather than the LM4780s, but your amount of heatsinking seems light. Is that an aluminum angle bolted to the rear chassis panel you are using to essentially heatsink the chips into the chassis? How warm are your chips running?
Click to expand...

Hi Robert,

Thanks. They are LM3875s.

The heatsink is two pieces of alumimum angle, 40mm x 3mm thick and about 300mm long. This is a all metal case as well, so it appears to be more than adequate for my use. It does get warm but even after many hours I don't believe its warm enough to be a problem.

Many of my test setups use much less angle (180mm) without getting hot, even after hours of playing. You have to remember these chips are designed for use in small appliances such as car radios. I haven't tried a LM4870.

I have often wondered with Peter's designs, using blocks of metal are aimed at keeping the chips a little warm. :confused:

regards
 
Greg Erskine

Greg Erskine

Member
Joined 2002
Paid Member
rdf said:
Thanks Greg. Were the amps which worked well single transformer? My torroid is a 1000 VA from a dead Zen project so the amp will use ony one. I also have some 2" x 1/4" copper flat stock sitting around, my thought was to use a physical layout similar to the Peter's Patek but mount the single rectifier board on the bar's end opposite the amps and use the flat stock as heat sink and ground return.
Click to expand...

Hi rdf,

I think the attachment shows you how I did mine. A single toriod should be fine. I don't think you can go wrong following Peter's work. I dream of being as skilled as Peter. :D

regards
 

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M

Magsy

Member
Joined 2005
Just want to say a big thanks to Peter for the service he provides! :) I hope you have a nice time in Cancun :bawling:

I ordered the DAC kit on the weekend and it arrived in the UK today!! I wasn't expecting it but its a very nice suprise and gives me something to do over the holidays.

I've been banned from opening it until Christmas day though:santa2:

Some preview pics of a recently built Premium 3875 here
 

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W

wdavis009

Member
Joined 2005
Peter Daniel said:

A simple preamp implemented around OPA627 or AD815 might be a better solution, especially with chip amps, that work actually better with active line stages.
Click to expand...

Peter,

Thank you for the response and recommendation. I agree that an active line stage is what I need to do, but I would want to go with a tube unit if I did that. What about adding a simple buffer stage and paralleling or bridging the amp? I did replace the 10uF electrolytics on the PS board with 100uF PIO's to good effect. It now sounds pretty good when listening to Tracy Chapman, Diana Krall, etc. However, when I listen to anything more complex things begin to fall apart.

Wade
 
O

opt-e

Member
Joined 2005
Wiring.. how much does the type of wire matter?

Stranded vs solid core? Thin vs thick? Copper vs silver?

Ideally, what kind of wire should I be using for what purpose?
I see most people use heavy guage wire for power supply wiring and output wiring, and thin wire for low voltage signal carrying wires.
 
Sangram

Sangram

Moderator
Joined 2002
Paid Member
Whoopeee!

Many thanks for the prompt response Peter.

I have received my parcel today (with a mixed bag of 4780 kits and PCBs), from the other side of the world. That took just ten days, by ordinary post. Remarkable, in any sense of the word. It feels very substantially packed so I'll open it once I get home from work.

I see a busy New Year period in my Crystal ball! This monster will take time to build. Then mid year it's time for the DAC...
 
M

Magsy

Member
Joined 2005
:)

50ohm is computer and 75ohm is video, they are interchangeable in fit but you don't want to run spdif over anything other than pure 75ohm cables/connectors.

75ohm cable is easy to come by but the connectors are not so easy. Many claim 75ohm but they just take 75ohm cable, the connectors are 50ohm.

75ohm BNC's have a very small, or no centre piece (the white plastic)
 
Peter Daniel

Peter Daniel

Member
Joined 2002
audiosector.com
Paid Member
Magsy said:
Can anyone confirm the BNC Peter supplies with premium DAC kit is 75ohm? It looks like it has too much centre to be 75ohm to me...
Click to expand...

It is indeed 50ohm. I can get you 75 ohm version, but it will be $10 more.

The BNC connector I'm using is exactly the same as the one used in all Mark Levinson digital equipment.

I tried both 75ohms and 50ohms and subjectively I don't hear a difference.
 
Sangram

Sangram

Moderator
Joined 2002
Paid Member
I built one too and find it gets very warm, check your DC-offset and how big your heatsink section is.

I also find that the heatsink seems to slightly cool off at somewhat high power levels ~1 watt than at idle or just above idle (few milliwatts is what I mostly use as I'm never home before 10pm and live in a quiet neighborhood)..
 
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