[petrL]

Hi,

my SE-9 in the last months sometimes makes a crackling noise or bursts into the loudspeakers shortly after switch on. I think it is the period when capacitors are charging to B+. Afterwards everything is o.k. So I'm thinking that the electrolytic capacitors after 5 years may need replacement. But since I use the amp daily, it would be great is somebody could advise the original capacitor values, so that I can order them. They are not readable without removing the PCB from the amp.

[jqp]

try yuths @ nortech.com, copy mbarnes @ nortech.com

[petrL]

Ok., Mr. Barnes promptly forwarded my former message again to youths, but still no reply for more than one week. I think they already lost any connection with the OEM manufacturer (TS Audio). I'll have to order some 3 probable values (22uF, 33uF, 47uF) based on the physical size and voltage which must be 450 V at least - or to be with SE-9 disassembled for couple of long weeks 

[Wayne1]

The main power supply caps are 100 uF @ 450 VDC. One before and one after the choke.

The PS cap to the 12AX7 is rated 33 uF @ 450 VDC.

[yeldarb]

Mine was making some noise, too.  I pulled the tubes and cleaned the pins.  Noise has gone away.  Try this first.

[petrL]

Thank you, Wayne1! I already ordered smaller values, so will have to find 100uF. I didn't expect so high value because these are the same voltage, temperature and dimensions as the 33uF one...

yeldab: could be, but I changed rectifier first, then also ecc83, and el34 not so long ago. And the tubes (contacts) don't warm up in half minute.

[yeldarb]

The noise in mine came up in the left channel, almost immediately after turning the power on, cold start.  Tubes not even glowing  Maybe I got lucky, or maybe just coincidence, but when I rotated the tubes to see if noise moved, it went away.  So I cleaned the pins and haven't been bothered.

 I have wondered if adding some "reserve" capacitance would make it sound even better.  Let us know if you get any noticable improvement by a cap change.

[petrL]

After some discussions I did another trial and changed coupling capacitors, because this can be done easily. Auricap 0.33uF/400V instead of the original Wima 0.25uF/250V (bigger than Auricap!). Not yet enough cold starts to see if this was the fault. As expected, the sound has clearer highs and slightly better bass, but unfortunately the midrange sounds stressed. They still need some burn in.

yeldrab - at least I'll try to add C after the choke. .....But what am I doing? I'm satisfied with SE-9 sound as is.

[yeldarb]

Fired my SE9 up last nite, after a long unused spell.  Lots of noise in the left channel which went away quickly. Amp then sounded fine.

Any news on the cap replacement front?  Any suggestions as to brands?