Doug Self Preamp from Linear Audio #5

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#562
Eldam said:
Hi Forr,
Should I change something please for a 100 K inputt amp and a DAC outputting 1.5 V ?
Click to expand...
Currently the input impedance is 50 kOhm on the pin2 and the pin3 of the XLR socket. Is that not enough for your DAC output wihch should have a low output, probably far less than 470 Ohm ? If the gain of the preamp is too high, do just as JMK did or insert an attenuator before the input of the power amp. Built 680 and 330 Ohm resistors, the signal will be lowered by 9.7 dB
 
#564
graemed said:
Impressive build. Would you be able to show us inside as well?
Click to expand...

As requested.

IMG_0693_zpspzpa6uin.jpg


I hate drilling holes for standoffs, so I've used nylon computer standoffs to elevate the boards (main amp and I/O PCBs) off the floor of the enclosure. But the boards are really held in place by the nuts on the front panel and the screws on the back panel. Only the power supply PCB is mounted by standoffs that are affixed to the bottom of the enclosure. And even here, I used ColdWeld adhesive rather than drill holes.
 
#565
** Doug Self Preamplifier PCB Kits **

Here is the revised list of interested parties for this last round of Doug Self preamplifier PCB kits.

pchw - 1 kit - PAID
kissmurphy - 2 kits - PAID
Rick G - 1 kit - PAID
Flugelmere - 2 kits - PAID
hasenmuehle - 1 5x1 IO kit - PAID
gorkyh - 1 kit - PAID
J.M.K - 1 kit - PAID
quicklizard - 1 kit - PAID
graemed - 1 kit - PAID
Eldam - 1 kit - PAID
canyoncruz - 1 kit - PAID
sek - 1 kit - PAID
Mraudionut - 2 kits - PAID
Art M - 1 kit - PAID
Lutto - 2 kits - PAID

*> KITS WERE SHIPPED TO THE ABOVE PARTIES SATURDAY 10-01-2016 <*
 
#566
PICs of the Latest Doug Self Preamplifer

Below are PICs of the rev 1.3 PCB. Performance is identical to previous version. Changes for v1.3 amount to ...

#1) The BOM was made simpler. Previous version called for 2 version of 470uF capacitors. The board now accepts 6 Nichicon UES1V471MHM capacitors

#2) Some builders complained that the power connector needed to larger to accept a larger gauge of wire. As result the EURO power connector is now 5mm on center. It is specified to be a Phoenix #1755910 connector or equivalent

PIC_01.jpg

PIC_00.jpg

PIC_02.jpg
 
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#567
HaroldHill said:
As requested.

IMG_0693_zpspzpa6uin.jpg


I hate drilling holes for standoffs, so I've used nylon computer standoffs to elevate the boards (main amp and I/O PCBs) off the floor of the enclosure. But the boards are really held in place by the nuts on the front panel and the screws on the back panel. Only the power supply PCB is mounted by standoffs that are affixed to the bottom of the enclosure. And even here, I used ColdWeld adhesive rather than drill holes.
Click to expand...

You inspired me. I just ordered a case from the DIYaudio store.
 
#568
HaroldHill said:
As requested.

IMG_0693_zpspzpa6uin.jpg


I hate drilling holes for standoffs, so I've used nylon computer standoffs to elevate the boards (main amp and I/O PCBs) off the floor of the enclosure. But the boards are really held in place by the nuts on the front panel and the screws on the back panel. Only the power supply PCB is mounted by standoffs that are affixed to the bottom of the enclosure. And even here, I used ColdWeld adhesive rather than drill holes.
Click to expand...

Wow. Neat as...

Hope my build turns out to look as professional as this one. The enclosures readily available in Aus are not as good as this.

Thank you HaroldHill.

Graeme
 
#569
Hi Carl,

Thanks for posting the nice pics. 🙂

Carl_Huff said:
Below are PICs of the rev 1.3 PCB. Performance is identical to previous version.
Click to expand...

Excellent!

Carl_Huff said:
Changes for v1.3 amount to ...

#1) The BOM was made simpler. Previous version called for 2 version of 470uF capacitors. The board now accepts 6 Nichicon UES1V471MHM capacitors

#2) Some builders complained that the power connector needed to larger to accept a larger gauge of wire. As result the EURO power connector is now 5mm on center. It is specified to be a Phoenix #1755910 connector or equivalent
Click to expand...

Thanks for the improvements and for making it a little easier.

It doesn't look like you ran into any show stopper issues with the test build.

Cheers!
Rob
 
#572
kissmurphy said:
Hi Carl,

Thanks for posting the nice pics. 🙂 Excellent!

Thanks for the improvements and for making it a little easier.

It doesn't look like you ran into any show stopper issues with the test build.

Cheers!
Rob
Click to expand...

Yes!

With the exception of one cold solder joint (working too late into the night ...) the new boards came right up.

I have been listening to it intently for the last week. All is well.

Thanks again to Douglas Self and Jan Didden for making this available to the DIY community.
 
#573
"Love the wood case, is that mahogany ? also how did you get the printing on the front panel."

PJN,
i believe it is Walnut. My Brother gave it to me a while back. As for the Printing, go to
Waterslide Decal Paper, Image, Transfer Paper, Iron On, Decals. Black on the dark wood is kinda hard to read from a distance but looks COOL to me. Had to get the wife (a typesetter by trade) to re-do the template for the correct size of the front panel so everything aligned up properly.

Rick
 
#580
Using less voltage ?

Hi !

I already have a very good +/-15 Volts linear PSU.
Is there any drawback in using +/-15V,
instead of the +/-17 Volts recommended in the documentation ?

Thanks a lot ......

JM

(17V is the maximum voltage acceptable according to LM4562's datasheet)
 
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