Pumpkin preamp - More Boring Making Thread

[steenoe]

I hooked up the simplest imaginable DAC to my Pumpkin/AX setup. Just for fun and out of curiousity. (And ofcourse for liking a solder job!) How small and simple does it get? I dont know, but a DAC of 125X125mm is pretty small I guess! (5"X5") Here is pic of the front, its a TDA1543 DAC.

[steenoe]

Here is a pic of the gut's. It's all P2P wiring and the CS8414 is soldered to a standard DIP board. Counting the parts; I am pretty amazed that it plays music.

[steenoe]

Here are the connections. Why use BNC, you ask? Because the SPDIF standard says 75ohm impedance! The BNC is by far the easiest way to do that!
How does it sound? Not too well.....

[Zen Mod]

Originally posted by steenoe
Yes, that is probably the next step. I will try and figure out something that can be squeezed onto the board. It will have to be fed by the single-ended supply though.
Funny enough, there is a little room left on the perfboard
.........

"buffer for Blues" or Borbely buffer ( two N Jfets in toob fashion )

Originally posted by steenoe
.........
BTW, I consider rebuilding the Pumpkin and use 2 case's instead of 1. The wooden box is not able to dissipate the heat, really. It runs a bit warm, inside. Alternatively the top and bottom plates could be filled with holes, but that wouldnt look too good.

well - YOU asked for F4 capable preamp ; now suffer

I could make you one with 1/10 of dissipation , but that was outa fashion ........

[zeonrider]

Originally posted by steenoe


This might be the company that produce the cool looking heatsinks. Go through the catalouge and you will find some extrutions that look pretty much like those on the pic.



http://www.newtronic.dk/picture/upload/Pada_83_110.pdf

You sad the truth, model 8075 on page 7 but i, cuted left and right side. It look beter.

Regards zeoN_Rider

[Zen Mod]

Steen - I just tried for you that version ( if I'm not wrong - PD's ?) of simple 1543 DAC , feeding 22K input impedance of next stage ;


there is not enough dynamics ; sound is -sorta interesting (different than SSDac with xformers , certainly ) but just with occasional glimpse of life in it ; details are almost there , but everything is somehow flat ;

you'll always know that impedance mismatch is in case , if you have wakoo response of volume control ....... turning it up almost without normal response , and then suddenly you have enough volume ;

purely subjective described ......

[Magura]

Originally posted by steenoe


This might be the company that produce the cool looking heatsinks. Go through the catalouge and you will find some extrutions that look pretty much like those on the pic.



http://www.newtronic.dk/picture/upload/Pada_83_110.pdf

But isn't that what we have been using since forever?


Magura

[housing]

Look.........Look!@@@@

[housing]

Originally posted by jacco vermeulen
Very nice, what is it ?

A pair of Pumpkin and Shunty!

The heatsink on the Pumpkin is an old cheapie NOS that I found in the cabinet. It was bought long time ago for less than US$2. I saw and adapt it for use on the Pumpkin. Now it measures the full width of the PCB and is 50mm high, 15mm deep and has a base plate of 5mm thick, fixed with stainless steel bolt and isolated from ground plane with teflon washers.

The heatsink for the pre-regulator of the Shunty is also an old cheapie NOS that I bought for less than US$1.0. It protrudes a couple of mm beyond the PCB. The CCS and the shunt Darlington transistors are installed on 2 RISC CPU heatsinks that measures 51mm x 54mm and 16mm deep that have base plates of 5mm. The 2 heatsinks are bolted together using 25mm Al flat bar. These CPU heatsinks are provided with fans but have been taken out and thrown away! They cost about US$2.50 a piece in the junkyard here.

[housing]

Originally posted by Zen Mod


it's always nice to see other fellow junkdog

I just can't find anything better than these CPU heatsinks in the local market. They looked like gems to me when I spotted them. They have some 3M VHB (Very High Bond Joining System) glue on the base plate and I find the most convenient way to remove it is to rub it out with my bare thumb. Now I can't go to the US for I have lost all my finger print on my thumbs!