Iron Pumpkin(s) and other smaller vegetable animals, Tips 'n' Tricks thread

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#421
Plott said:
And the issues: the main issue is the hum 🤔 The transformers are about 70 cm away from the amp, but there is hum. Weird: the amp itself produces some mechanical hum/resonances - the noise comes from inside, it is like the "sound" of an old transformer with loose windings, or I don't know. In the next days I will try to find out where the source of the hum is.
But it sings beautiful 😍
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"amp" - you're speaking of power amp, being close to Iron Pumpkin?

anyway, be sure that at least those panels you have in Iron Pumpkin are connected to Safety GND, giving some shielding
you did it simpy beautiful, but your case is far from (say) Modushop 3U/280(350) with Fe panels, which is my preferable solution , considering how sensitive AVCs are for external pumping magnetic fields


did I said Fugly! ?

anyhow, move that amp away ....... :clown:


- if you're speaking of preamp itself (?!?!?!?!?!) ....... then you must give me more info to figure it out what's happening ........

jhstewart9 said:
Looks like you have an HP 141 Spectrum Paralyzer system. Is it the vers with the storage CRT?
That setup was an easy sell, we did a great business here with them. A joy to demo, my favorite!🙂
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entire setup in linked post is of my Buddy Zeljkor.... so I can't tell much
 
#422
Many thanks fellas, glad you like my Pumpkin 👍 :deerman:
Many thanks ZM for the official fugly nomination :yes::worship:
"Amp" is the preamp, but to begin at the end: the main hum is caused by - yes - the power amp right next to the Pumpkin.
So one issue solved.
The plates are of course connected to the safety gnd.
The "noise" in the preamp is a slight hum from - I think - some or one of the relais, in certain Zen amount positions, but this hum don't comes everytime even in the same position, switching further and back and the noise is gone. But it comes in another position. This noise comes not through the speakers, it comes even if the power amp is completely disconnected.
Input 1 (SE) and input 5 (bal) have higher hum (through the speakers).
So I have to re-install my racks so that the Pumpkin is far away from the power amp.

But I don't know how to solve the issue with the "relais noise" 🤔
Anyway, the sound is wonderful 😍
 
#425
Zen Mod said:
Modushop 3U/280(350) with Fe panels
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Dually noted…must check my stockpile of cases.

I went through a “noise issue” that appeared after I finished my NOS TDA1541 DAC.

Eventually figured out the DAC was the problem on the shelf above my preamp. I ended up putting a steel plate on the shelf under the DAC and everything was quiet again.

My Pumpkin/Turtle was shifted down in the “Que” once the Mighty ZM helped me add iron to my DCB1 in the KISS thread.

Every time I see one finished I sigh…
 
#428
You mean it is this relais which makes the noise?
Okay, no real problem, it just makes me crazy :rofl:
With Takamisawa would be better? Just because they were used originally.
Maybe I should change the relais, but the Takas are not available now...
It is weird that the noise is not always here. Sometimes it goes when switching further, sometimes it stays no matter in which position... The same occurs sometimes with the attenuator relais, same noise...
 
#430
dunno what voltage you have at drain of regulating IRF510, maybe it is borderline low (it depends of your xformer itself)

in that case it is possible that relay voltage is having excessive ripple, it is deliberately made without too much capacitance neither in front of IRF, nor after

measure what's voltage at IRF drain so we will see

Zettler relays are rare ones for which I have both confirmation and experience of being equal quality as Fujitsu, at least that size/type

it was major pain in one moment (batter saying - period) getting Fujitsu ( or any other decent) relays; that's the reason why I now have appropriate files for these and also smaller (micro :rofl: ) ones - just in case, to prevent whatever parts market is bringing as surprise

availability of parts is gone nutz and unpredictable ..... it doesn't matter what's price and complexity of production

heck, I believe that even Pa's Crew must be more clever than usual, when checking their parts inventory

edit: you can increase C2 cap

now it's 10uF, put there whatever you want

maybe easier way of doing that, without messing with Motherboard is to solder it at volume switch pcb, across + and - wirepads

it'll cover entire circuit that way

470uF to 1000uF/35V will do
 
#434
Plott said:
Well, this voltage seems to be quite low. With 24vac input there should be about 34vdc - or is this drop because of the load of circuit?
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if there is confirmed 24Vac, you can increase C1 to, say, 100uF/35V

again, I intentionally didn't put higher capacitances there, majority of small xformers, Donut or other ones, are having poor regulation factor (that's normal) thus with so light load AC is higher than nominal 24Vac
 
#439
After eliminating the problem with the nervous relais and with the nervous myself :rofl: I moved the power amp just 50 cm away from the Pumpkin - and there you have it, the Pumpkin is dead silent, absolutely no hum even at the highest volume position :worship:
And I think, the zingy relais had some influence regarding sound quality (it would be logical), now it is absolutely unbelievable gorgeous😍
 
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