Threshold sa6

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Me thinks NP had already left the stage before the SA/6e was released.

MSRP of the monaurals was around 10% more than the comparable stereo Threshold model.
The 100W monaural SA/2e did ~$7K/set in the US around 1990, and in the EC the equivalent of ~€10K.
The SA/6e shares the chassis of the SA/2e, same 800VA size toroid, identical size output stage.
Different is the big can size, the SA/6e has twice the 60KuF/Ch. of the SA/2e.

Asking price for a mint condition SA/2e is likely somewhere around €4.5K, also some 10% more than what to expect for the SA/4e stereo model, i'd estimate the SA/6e to fetch a somewhat lower price.
Add some bumps and scratches, and it's down the hill you go.
 
I have recently (12 months) bought a pair of SA/6e in France.

You have to know that the SA/6e are extremely rare in Europe because of an original selling price that was stratospheric... (due to the European importer). I have bought them for 5k€ whereas the seller asked 6k€.

I would bet that it is possible for you to find a pair of them < 5k$ in the States.

Good luck,
 
Dear all,

I use this old topic concerning the SA/6, because I have a problem with the SA/6 I recently purchased, so some advices would be welcome.

Basically I think it's a ground problem : if I let the amps switched on and connected to the speakers, I have no noise at all, just a very low "Shhhh" in the tweeters, but as soon as I connect a source (solid state ou tube one), using RCA or XLR, immediately I can hear a noise in the woofers. If I switch off the preamp the noise is still there, I have to remove the power chord of the source to make the noise disapear. I have had the same problem with a SA 3.9e, I sold it as I thought it was not compatible with my installation, but the SA/6 do the same. I have also a pair of tube (845) monoblocs, and when I put them in the system with the same cables, no problem at all. I also tested an Accustic Arts power amp without any problem.

The only way to remove the noise is to disconnect the ground of the SA/6 power cable, which is not safe.

For me it looks like a ground problem through interconnect with the Thresholds. I was supposed to make them upgraded, but as it's quite expensive I won't do it if this problem is not solved before (or if it can not be solved during the upgrade).

So any kind advices would be welcome, I would be really disappointed to sell them for a so stupid reason.
 
Sorry for the double post, I would just add that the ground pin of the power socket is directly linked and screwed on the bottom of the case. On the third picture the cables look strange, they seems connected together (bottom right of the picture, below the RCA connector)
 
Official Court Jester
Joined 2003
Paid Member
I wouldn't worry about those cables

can you see anything anywhere , as connection between main audio GND and case ?

I am blind , but this time double ...... ;)

Pa is your man , but better to check by your self

btw. that's adorable chunk of hardware ....... don't despair , hum prob will be solved

make one test - connect just one input cable from preamp , tell is it humming ;

connect both , tell how is humming

whatever - we must find present element (most probably plain wire) between gnd and chassis and replace it either with NTC or Graetz bridge
 
Hello :)

I did the test tonight, connecting RCA 1 to the amp 1, the hum starts in speaker 1, no hum in speaker 2, if I connect RCA 2 in amp 2 (removing RCA 1 in amp 1), I have hum in speaker 2 but not in speaker 1. If I connect RCA 1 and 2 both amp 1 and amp 2, I have hum in both speaker

The plain wire between ground and chassis is the green/yellow which starts on the ground pin of the power socket of the amp and which is screwed on the other side in the chassis ? I saw it when I took the pictures. There is an other thin cable connected to the chassis with the same screw and which goes I don't know where below the big caps.
 
The one and only
Joined 2001
Paid Member
For the purpose of testing only , I suggest that you go to the hardware store
and buy a "cheater plug" which is a 2 prong male that goes into the AC wall
receptacle but which has a 3 socket female. This can be used to temporarily
isolate the AC line earth ground from the chassis and break a potential ground
loop.

:cool:
 
Thanks a lot Nelson I didn't expect an answer from you, I just discovered these old Thresholds and their incredible qualities a few month ago, and I'm very happy to get some words from you :))

No cheater plug in France but I can simply disconnect the ground in my power cables just for testing, I'll do that tomorrow after work, it's time for sleeping here :)

Concerning the upgrade of the blocs, the big Malaury Caps can be replaced by BHC ALS30 63V 47000 µF or F&T Elco 63V 47000 µF ? These are the caps used for this purpose in France, but are there better options (there's a limit in terms of size, no more that 75 mm diameter) like the Felsic 105 TFRS ?

Also the FRED bridge rectifier can be changed for the IXYS 68A 600V ?

These parts have been used in the SA/3.9e updraged I had before the SA/6, and it was really working well.

Ok I'll try to remove the ground tomorrow and see what happen.

Thanks !
 
I did the test so the results are :

- Without ground connected both amps are silent, nothing in the speakers.
- If I connect the ground on amp 1, hum appears in speaker 1, speaker 2 remain silent.
- If I connect the ground on amp 2, hum appears in speaker 2, speaker 1 remain silent
- If I connect the ground on amp 1 and amp 2 hum appears in speakers 1 and 2.

What would be the next step ?

Thanks.
 
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