Pumpkin preamp - More Boring Making Thread

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#322
The brass things i posted (P789) are not DIY, they're serial production heatsinks for 92s.
The bottom edge is flared to add some spring resistance that makes them clamp the little ones and not slide down slowly.
Making them like that is not all that easy, you'd have to machine a 2-piece mold to press the flare.

The easy way would be to fold a thin strip of brass/copper around the devices, then tighten it with a chica plastica
(Ruben Blades: fav. actor and all-time abfav. salsero)
 
#323
Thx a lot Jacco
I post this your pic again ( If I may)

Interesting too are the isolation of zistors legs ,
I didn't notice it the firts time a saw the pic.
Very nice and accurate work.

Manu
 

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#324
Leads have a considerable effect on the cooling factor of semis/resistors, from that on their operating temperature.
(for lesistols, the distance to the PCB is also vely impoltant, read a tech paper on lead length and mounting height from e.g. Vishay)

An amp case needs to be ventilated, the airflow within the case is not a stasis situation.
Most of the cooling will take place at the top of the Baldricks if the leads are insulated with teflon leggings, more uniform

Some day i'll get the matches back to Guernica
 
#325
jacco vermeulen said:
The brass things i posted (P789) are not DIY, they're serial production heatsinks for 92s.
The bottom edge is flared to add some spring resistance that makes them clamp the little ones and not slide down slowly.
Making them like that is not all that easy, you'd have to machine a 2-piece mold to press the flare.

The easy way would be to fold a thin strip of brass/copper around the devices, then tighten it with a chica plastica
(Ruben Blades: fav. actor and all-time abfav. salsero)
Click to expand...


Manu said:
Thx a lot Jacco
I post this your pic again ( If I may)

Interesting too are the isolation of zistors legs ,
I didn't notice it the firts time a saw the pic.
Very nice and accurate work.

Manu
Click to expand...


someone here have short memory

lazy greedy boyz

lookie lookie

and - makin' these Jaccovitty cool stuff is POC - you don't need even to make that skirt of one edge

http://www.diyaudio.com/forums/showthread.php?postid=1237712#post1237712
http://www.diyaudio.com/forums/showthread.php?postid=1237714#post1237714
http://www.diyaudio.com/forums/showthread.php?postid=1244829#post1244829
http://www.diyaudio.com/forums/showthread.php?postid=1244830#post1244830


ya can do it that way too ....... even nicer

edit - for Manu :

just a little memo :
http://www.diyaudio.com/forums/showthread.php?postid=1247765#post1247765
 
#334
hershann said:
substitute with film cap
Click to expand...

Better any cap across a rectifier diode than no cap, stuff like distortion figures and tolerance don't mean sheet for diode damping.
Cheapo cookybookie says better add some ceramics on the next orderlist, Z/X/NPo ceramics are superior to any film as rectifier bypass and cost mucho less.
(esoteric pric-picks an NPo/COG, 3.9pF-100nF)
 
#335
hershann said:
Are terminal blocks to allow easier testing and rearrangement of configuration a bad idea for audio pcb boards?

her shann
Click to expand...

I usually let them sit for the PSU connections. Its very convenient when you have to take it apart. For the signals its mucho better to solder the leads directly to the boards.



🙂
 
#336
jacco vermeulen said:


Better any cap across a rectifier diode than no cap, stuff like distortion figures and tolerance don't mean sheet for diode damping.
Cheapo cookybookie says better add some ceramics on the next orderlist, Z/X/NPo ceramics are superior to any film as rectifier bypass and cost mucho less.
(esoteric pric-picks an NPo/COG, 3.9pF-100nF)
Click to expand...

Is it true for any kind od Rect.-Diode?
Shotky, Soft recovery, ultrafast etc...?

Manu

Je commande?
 
#337
Very high efficiency speakers. . .

While waiting with eager anticipation for the Pumpkin/Shunty boards, I've been collecting parts out of my junk boxes, and figuring out what I need to order. However, I'm thinking that I may not need the truly manly voltage swing of the Pumpy/Shunty into the F4 with my 106db/w/m DIY Edgarhorns. . .

I've followed the threads on "how" to lower output, but what is stumping me is "how much" I ought to be considering -- I don't want to be running the volume control just cracked open. A pot can be touchy enough, and with stepped attenuators I've found that it is *always* one click to soft, the next click too loud. . . 😱

I currently run the Edgars with a Brenneman cathode follower tube integrated with a whopping 10 wpc, and usually never have the volume control more than 1/4 open.

Suggestions? 😎

It would be nice to have a volume control with very fine control down where I actually use it, and I don't care if it makes 6dB steps at full volume, 'cause it never gets close to that high!

Thanks for your time -- and thanks for the most interesting and entertaining DIY threads I've ever come across. 🙂 :cheers:

Steve Z
near Libby, Montana USA
 
#338
Re: Very high efficiency speakers. . .

zettelsm said:
While waiting with eager anticipation for the Pumpkin/Shunty boards, I've been collecting parts out of my junk boxes, and figuring out what I need to order. However, I'm thinking that I may not need the truly manly voltage swing of the Pumpy/Shunty into the F4 with my 106db/w/m DIY Edgarhorns. . .

I've followed the threads on "how" to lower output, but what is stumping me is "how much" I ought to be considering -- I don't want to be running the volume control just cracked open. A pot can be touchy enough, and with stepped attenuators I've found that it is *always* one click to soft, the next click too loud. . . 😱

I currently run the Edgars with a Brenneman cathode follower tube integrated with a whopping 10 wpc, and usually never have the volume control more than 1/4 open.

Suggestions? 😎

It would be nice to have a volume control with very fine control down where I actually use it, and I don't care if it makes 6dB steps at full volume, 'cause it never gets close to that high!

Thanks for your time -- and thanks for the most interesting and entertaining DIY threads I've ever come across. 🙂 :cheers:

Steve Z
near Libby, Montana USA
Click to expand...


did you downloaded Cook Book ?

http://czsr_bac.on.neobee.net/The Pumpkin & Shunty.pdf


just say -yey or ney , and I'll answer , or will not ........

:rofl:

edit :

it's really not important did you downloaded it ; what is important - did you read it ?

:devily:
 
#340
Cookbook/gain question

Yes, I did download and read the Cookbook, (and I thought it was a great thing for you to do). I believe I understand the "how to" part of lowering the gain/voltage swing of Pumpy. But maybe I missed something. I've had the flu for the last couple of days and haven't been in my right mind. :xeye:

What I am not sure about is "how much" to lower the gain. Or perhaps I don't need to lower it at all. I don't mind using the lower part of the pot or stepped attenuator, so long as I have enough control over small adjustments without always hunting and being too loud or too soft.

:dead:

I tried a a well-thought-of Chinese 2A3 integrated amp a while ago with my DIY Edgarhorns, and besides being unacceptably noisy, it was too loud at the third click of the stepped attenuator. :hot:

So maybe all I need to do is figure out the right range of potentiometer. I remember reading that a lower value is theoretically better for performance

Am I barking up the wrong tree? 😕

Feel free to heap ridicule on my head!

Steve Z
Libby, MT USA
 
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