Salas DCG3 preamp (line & headphone)

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Thanks. Will check with load before. Or I can just bring down the psu voltage a little with a resistor swap.

There are little Mosfet adjustable constant current load things you can make for such jobs since you test various stuff often. Like this Pico Load Kit - 2 Amp Adjustable DC Electronic Load - ubld.it - TrueRNG and Electronic Kits

Unless you get something like this :D

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


For now though make do with this :)

wholesale-10x-axial-lead-ceramic-cement-power.jpg
 
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We have music :D I completed the assembly of my DCG3 on its plank of wood and spent a pleasant couple of hours listening to Act 1; Kate Bush Before the dawn and Yello Touch on headphones. The headphones are an old pair of Leak 300 isodynamics which I bought in the early 1980's. they had been at the back of the wardrobe for close on thirty years and I was surprised that they hadn't disintegrated never mind sounding as good as they do.
The bias is running at 122ma and offset is sitting at 0.01/0.02mv with the heatsink which is a piece of 10mm thick alluminium 250x80mm sitting in the upper 30's.I'll check that tomorrow when I find my t/c for my dmm.
Gonna have a good listen tomorrow through the PMC's.
Thank you Salas another good one:cheers:
 
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That's great. Off to a nice start then. Are those cans planar magnetic type by any chance? Old planar ones were heavy in general lacking highs never challenging a Stax. You will surely discover more music tomorrow on the PMCs

P.S.
Plank ancient diy ritual assembly photo required :D
 
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That's great. Off to a nice start then. Are those cans planar magnetic type by any chance? Old planar ones were heavy in general lacking highs never challenging a Stax. You will surely discover more music tomorrow on the PMCs

P.S.
Plank ancient diy ritual assembly photo required :D

Definitely looking forward to listening through the main system.I will post some pics tomorrow. A bit of information here.

IC/WTT: Leak 3000 vintage ortho(NOS in box)
 
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They are planar magnetic alright and a very rare model to have at all not to mention intact these days. Some collector somewhere is surely looking for.

Did you manage any good levels at 3x with them? They must be very difficult to drive anyway even if the magnets are potentially still strong enough.
 
Question about the LED orientation on the boards:

Typically the square pad on the pcb indicates cathode (neg) I think. The silkscreen on the pcb says square pad is positive. I believe the silk is correct? Get this wrong and bad things could happen.

Silkscreen is correct?
 

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They are planar magnetic alright and a very rare model to have at all not to mention intact these days. Some collector somewhere is surely looking for.

Did you manage any good levels at 3x with them? They must be very difficult to drive anyway even if the magnets are potentially still strong enough.

A collectors item; I could be sat on a fortune:D

With 3X gain and listening to cd's I have the volume control between 12 & 2 o'clock.
 
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Full modern measurements, nice. About 94dB/mW with very linear mids but with more droop in the highs than in the lows that does not seem friendly for EQ compensation due to THD rise in bottom and highish octaves from as low as 90dB. Should be a sweet vocal headphone subjectively. Medium ease of drive, medium loud clean SPL. Says DIY mod, maybe some foam behind or a wooden cup or both.
 
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The resistor are MFR5 half watt 1% metal films.Others are a mixture of Holco H8 and RC55Y's.
Yes I connected signal ground to mains and there was no hum through the cans with 2/3rds volume.
I am going to have to experiment a little with foam backing on the headphones or see if I can knock up a wooden cup for the back of them. It should prove interesting.