"OffTopic" @
2004-05-08 17:01:42 UTC
This little 15W 2xEL84 based amp has always been my favourite for singing
tone at less than paint-peeling volumes. Granted, I chucked the Sovteks in
it and replaced them with NOS GEs (preamp) and EHs (PI & outputs), and I
replaced the speaker with a Weber Blue Dog. BUT, even stock this amp sounds
inspiring. The one thing driving me nuts though was the persistent 60Hz hum
that was always present, particularly in light of the fact that Traynor
makes a big deal about the great S/N ratio of this model in their
advertising copy. My Traynor YCV40 was extremely quiet by comparison. I
searched the net and found that I wasn't the only one with this problem. I
finally resorted to calling the folks and Yorkville and was provided with
two suggestions for improvement:
1) torque of input jack nut insufficient for providing chassis ground (that
wasn't it in my case)
2) routing of ribbon cable from preamp PCB to effects loop PCB (mounted on
chassis rear) incorrect
It was number 2. The main problem was its routing close to the preamp PCB.
Lift the cable away and the level of 60Hz hum noticeably changes. Also, the
effects loop PCB was unnecessarily rotated a full turn, shortening the
available cable length by adding another fold, thus causing the choice of
less-than-ideal routing.
CAUTION: all precautionary statements about working on tube amps apply. You
can seriously hurt yourself. If you are not comfortable or experienced with
high voltage electrical gear, have this done by a tech.
The fix: disconnect the speaker and drop the chassis. Remove the chassis
bottom cover plate and reconnect the speaker (do NOT operate without the
speaker connected!). Remove the effects loop sub PCB (three jack nuts) and
rotate it 360 degrees to remove on fold in the ribbon cable, then reinstall.
Now route the ribbon cable from its preamp PCB origin DIRECTLY towards the
chassis rear wall, providing a single 90 degree foldover near the chassis
wall. Keep the cable as close to the preamp PCB surface and as close to the
chassis wall as possible while aiming for the effects loop PCB. With the amp
running, you can find the best routing by ear. I had to remove to chassis
grounding posts to facilitate a clean routing, but I am very anal about
this.
The pain-in-the-ass factor of this fix is relatively high due to the
mechanical layout of the amp but well worth the effort. My amp is now quiet
as a mouse.
tone at less than paint-peeling volumes. Granted, I chucked the Sovteks in
it and replaced them with NOS GEs (preamp) and EHs (PI & outputs), and I
replaced the speaker with a Weber Blue Dog. BUT, even stock this amp sounds
inspiring. The one thing driving me nuts though was the persistent 60Hz hum
that was always present, particularly in light of the fact that Traynor
makes a big deal about the great S/N ratio of this model in their
advertising copy. My Traynor YCV40 was extremely quiet by comparison. I
searched the net and found that I wasn't the only one with this problem. I
finally resorted to calling the folks and Yorkville and was provided with
two suggestions for improvement:
1) torque of input jack nut insufficient for providing chassis ground (that
wasn't it in my case)
2) routing of ribbon cable from preamp PCB to effects loop PCB (mounted on
chassis rear) incorrect
It was number 2. The main problem was its routing close to the preamp PCB.
Lift the cable away and the level of 60Hz hum noticeably changes. Also, the
effects loop PCB was unnecessarily rotated a full turn, shortening the
available cable length by adding another fold, thus causing the choice of
less-than-ideal routing.
CAUTION: all precautionary statements about working on tube amps apply. You
can seriously hurt yourself. If you are not comfortable or experienced with
high voltage electrical gear, have this done by a tech.
The fix: disconnect the speaker and drop the chassis. Remove the chassis
bottom cover plate and reconnect the speaker (do NOT operate without the
speaker connected!). Remove the effects loop sub PCB (three jack nuts) and
rotate it 360 degrees to remove on fold in the ribbon cable, then reinstall.
Now route the ribbon cable from its preamp PCB origin DIRECTLY towards the
chassis rear wall, providing a single 90 degree foldover near the chassis
wall. Keep the cable as close to the preamp PCB surface and as close to the
chassis wall as possible while aiming for the effects loop PCB. With the amp
running, you can find the best routing by ear. I had to remove to chassis
grounding posts to facilitate a clean routing, but I am very anal about
this.
The pain-in-the-ass factor of this fix is relatively high due to the
mechanical layout of the amp but well worth the effort. My amp is now quiet
as a mouse.