Technik > Tech-Talk Amps

Re: Suche Netztrafo für MAC 4C - A52 Amp

<< < (6/6)

ricothetroll:
Hi,

I'm sorry to speak here in english, in a german forum, but here seems to be the only place with people experienced with this amp.

I have one that is working quite well but has a lot of hum at the output (about 300mV pp).
The hum seems to start at the phase inverter. It happens even with the first preamp tubes removed. It stops when the phase inverter tube is removed. I tried swapping the tubes and replacing them with new ones, but it didn't help a bit.

I see people here talking about mods in the power supply, but I don't understand most of what's been said (google translation is pretty poor for technical translations).

Can someone help me understand the discussion that occured in this thread ? Are there clues to help with my hum issue ? Has anyone ever had this amp hum-free ?

Thanx in advance...

Best regards.

Eric

DerDomze:
Hello Rico,

i think this thread basically describes the powersupply of the mentioned Amp. first a  replacement PowerTransformer and Choke was required.

I didn't read the whole thread word by word but at first sight i could not find anything regarding hum-problems, but regarding temperature and cooling..

this thread seems to be the second Part of:
http://www.tube-town.de/ttforum/index.php/topic,18739.msg189080.html#msg189080

and here there might be schematic which could help:
http://www.tube-town.de/ttforum/index.php/topic,4232.msg34793.html#msg34793
http://www.tube-town.de/ttforum/index.php/topic,8324.msg72416.html#msg72416

regarding your hum: is it
-50/60Hz -> hum from VAC supply
-100/120Hz -> remaining ripple after rectification

BR
Dominik

Racing:
Hm.
As a reflection,i´ve got a 2C at the shop since ages (my own amp) and the differences between the two models is nothing short of staggering.

First up the 2C uses a halvwave rectifier. Second up it uses transistorized entry stages for SOME of the channels.

I opted to convert mine into taking 4pcs of EL-84´s (the 2C is an "18 watt" amp stock),and that made me end up swapping the outputtransformer and mains transformer both. While at it i made the amp all tube driven.

Reverb is transistorized for the 2C as well.

Navigation

[0] Themen-Index

[*] Vorherige Sete