Pumpkin preamp - ordered by Steen , official making thread

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#121
I was just tryin to bait you with the old chap remark.....failed miserably...

seriously, it does sound good without a pre, the original spec on the SB said 2 volts and if thats correct then its got surprising clout......I'm surprised but I'm loving it!!

all except the 50 cycle buzz which I'm trying to track down at the moment....I may have made the same mistake as with the F2 and crammed stuff(the tranny) in a bit too close...we'll see

Ed
 
#124
vitalstates said:
Ok..
You play baldrick and I'll play bladder....

now, Baldrick, where do I start looking for the cause of this damned buzzing????
Click to expand...


besides that this thread is official :Pumpkin: building thread and that OT isn't wellcomed here ( a you can see from all previous posts) ...........

-lemme ask few Qs (very cunning ones ! ):

do you have bUzzzzzzzz with shorted inputs?

do you have bUzzzzzzzzzz few moments after powering OFF that dreky amp?
 
#125
oh I do feel good playing OT with Mr OT himself.....apologies

1. yeah the buzz is with shorted and open inputs
2. buzz stops when switch is flicked off
3. can't measure any ac with dmm it only goes to 3 decimal places on 2v setting, i.e min reading is 1 mv.
4. spks are 96db average , which is why its probably annoying........

I'll get the scope out tomorrow and move stuff around.....seriously, I didnt mean to take your thread OT but thanks for sticking with me....

regards

Ed
 
#126
vitalstates said:
oh I do feel good playing OT with Mr OT himself.....apologies

1. yeah the buzz is with shorted and open inputs
2. buzz stops when switch is flicked off
3. can't measure any ac with dmm it only goes to 3 decimal places on 2v setting, i.e min reading is 1 mv.
4. spks are 96db average , which is why its probably annoying........

I'll get the scope out tomorrow and move stuff around.....seriously, I didnt mean to take your thread OT but thanks for sticking with me....

regards

Ed
Click to expand...


how much caps you have in PSU filtering ?

are input RCAs isolated from chassis ?
have you PTC between safety and audio gnd?

is it 50 or 100 HZ buzzzzzzzz?

it's same in both channels?

is it same in one channel if you remove supply to other channel


etc

one by one ,please
 
#129
jormajj said:
The Pumpkin and Shunty PCBs arrived today, Thanks Choky and OLy !

Great looking boards :worship:

Here are some examples of heatsink types fitting on the PCBs
( 50 mm high):

Fischer
SK81-50 SA
SK75-50

Austerlitz
KS100.3-50
KS32.1-50E

jormajj
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LL where are you ? If jormajj got his PCB's yesterday in Finland you should be half way through building your Pumpkin today..
😀 Are you getting a little slow on the trigger ?😀 😉
 
#130
ROVSING said:



LL where are you ? If jormajj got his PCB's yesterday in Finland you should be half way through building your Pumpkin today..
😀 Are you getting a little slow on the trigger ?😀 😉
Click to expand...


jormajj's :Pumpkin: was in first set of envelopes - some 8-9 days ago ;

LL's and yours (if I'm not mistakin' ) is in second set of envelopes ;

I tracked it to leaving Serbia border , two days ago , so LL can see little package in next week, I suppose ......

edit:

did LL forwarded pdf to you ?
 
#134
Well - thank you fore your expert advise - helpfull and friendly as usual😀
I'm looking forward to get the pumpkin /shunty PCB's they will look nice in my collection.
I am doing sports 4 or 5 times a week and that gives me less time to DIY - to be honest my children are doing sports i'm just the driver!
Hopefully i'll get a little more time for DIY as they grow older, and then i have a lot of projects laying around - if i can remember where they are at that time...😀
 
#135
vitalstates said:
Hi choky

sorted the F4 buzz, it was RF from the tranny, just the same problem I had with the F2. For info, the common factor is clairtronic transformers....

This cured it completely:
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why on earth you place that drek ditto to input terminals and cables ?

turn it around - place it on blind front plate , place PSU pcb in middle of amp ;

find biggest tuna can , eat what's in it , and make lalalala shildie pot for crummy donut
 
#136
patience mon brave, nothing is fitted in that pic, its all just resting in free space......I just took the pic to show the orientation that works.....

btw we don't have tuna tins that large(well maybe we do but I havn't seen one)...but I'm going to mount the tranny on a bracket in roughly the same place it is shown and turn the ps board round 90 degrees where is has more room.........its not artistic, but hey it works


this is what it looks like when lying flat on the floor in the middle
 
#137
vitalstates said:
patience mon brave, nothing is fitted in that pic, its all just resting in free space......I just took the pic to show the orientation that works.....

btw we don't have tuna tins that large(well maybe we do but I havn't seen one)...but I'm going to mount the tranny on a bracket in roughly the same place it is shown and turn the ps board round 90 degrees where is has more room.........its not artistic, but hey it works


this is what it looks like when lying flat on the floor in the middle
Click to expand...


well - since all is sorta dismantled now - try it as I said ;

there is less harm in routing 220 line all the way to front plate , than keeping lousy xformer near sensitive lines

(I didn't invent that , so - don't thank me :clown: )
 
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