Threshold Fet Ten HL/E - balancing issue

[albe58]

Hi all,
just joined the forum after long and careful reading your very interesting forum!.
I have a Threshold Fet Ten HL/E and a Nakamichi PA-7EII that gives (a lot of) power to a couple of Tannoy HPD 15’’ in a GRF cabinet made by myself.
The overall system sounds (imho) very good and I’m quite satisfied about this “mix” of components (there should be a good synergy among them).
But, there is always something that goes wrong (Murphy theory?)
I recently discovered that the overall sound scene is not balanced properly; I have more “sound” on the left side, so I have to compensate by givin the Fet Ten balance knob 1-2 step more to the right channel.
The strange thing is that the same “behavior” has been found by a friend of mine, who has the same pre Fet Ten HL/E.
Now the question: is anyone that experimented the same problem? Is it something already known about Fet Ten HL/E? is there any solution to fix this issue?


Many thanks for your contributions,
Alberto.

[Zen Mod]

if you swap left-right channel interconnect , between amp and preamp , there are two possible scenarios :

weaker channel stays on same side as before - amp need fixing

weaker channel goes to other side - amp is good , and you need same swapping exercise with interconnects - between preamp and source .
same - if , after swapping ICs , weaker channel is still on same side , then preamp is in case and need fixing

in any case - be sure that all interconnect contacts are clean , and that some funny window glass near louder speaker is counted in entire story

[albe58]

Originally Posted by Zen Mod

if you swap left-right channel interconnect , between amp and preamp , there are two possible scenarios :

weaker channel stays on same side as before - amp need fixing

weaker channel goes to other side - amp is good , and you need same swapping exercise with interconnects - between preamp and source .
same - if , after swapping ICs , weaker channel is still on same side , then preamp is in case and need fixing

in any case - be sure that all interconnect contacts are clean , and that some funny window glass near louder speaker is counted in entire story

Hi Zen Mod, thanks for your contribution.
I've already done the suggested checks between pre & amp and between sorce & pre, the result is always the same: problem is on Fet Ten side.
Same situation for the room check (i.e. wall, windows, pictures, etc.): there are no significant differences between left and right side of the room.
Moreover, the same problem is experienced by a friend of mine who has the same preamp but, obviously, in a complete different setup (electronics, speakers, room, etc.).
I think that volume and/or balance knobs could have some problem.
Do you have any hint to better check the issue and establish proper fix?

Alberto

[Zen Mod]

unfortunately - I don't have direct experience with Fet10

but - preamp as preamp - you need to examine what's in question - going from back to front ;

so - even output of PC sound card as signal generator , connected via 1K pot and 2u2 cap , Sigjenny program set to 400Hz , and plain DMM as Vac meter connected to output.

inject signal after pot - right in line stage and measure both channels

then move forward - in front of pot , repeat measuring - always comparing two channels

there are many physical variables what's worth checking - almost every physical contact , switch , pot etc.

[Nounours18200]

Hi albe58,

I own a Fet-10 He that I have used with many different sources, different amps, different loudspeakers, and I have never faced this problem.

I have performed a significant upgrade on it (refer to this post: Threshold Lovers - Threshold - Fet-10 HE 'competition upgrade') because the Fet-10He can really be a top performer.

I fully agree with Zen Mod: you should follow his instructions to find where the problem comes from... a preamp is a preamp !...