Sansui Eight
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stereofun
Super Member
If you can physically check it out, you will need to turn it on - then after a few seconds you will hear a click if it has a relay, while not loud it is unmistakably. If you are buying online its more tricky - aside from asking seller, the dates can give a clue. A very rough split goes something like this: 1970 = no relay, 1971 = some with some without (the earliest relay I know of is February 1971) 1972 = Relay. The production date is on the yellow sticker on the back, 3rd digit indicates the year (eg. 2=1972). then next four digits are mm/dd
Trnsfmr
Well-Known Member
And I would add that the Eight without the relay has fuses in the speaker outputs, which are bar none the safest speaker protection you can get. That protection relay is just an electronic circuit that is subject to degradation and failure. If the unit has not been completely recapped, I would not trust the relay to protect my speakers.
I have a pair of NS-10s that an amp with a speaker protection relay fried one of the woofers that I still haven't gotten fixed. We now have fuses in all our speaker lines in the shop. They never fail to protect. And they are cheap too.
I have a pair of NS-10s that an amp with a speaker protection relay fried one of the woofers that I still haven't gotten fixed. We now have fuses in all our speaker lines in the shop. They never fail to protect. And they are cheap too.
slimecity
Super Member
Sorry to slightly hijack this thread but Trnsfmr what is a good value fuse to use for this application? I am building a Pass-designed class-A VFET amplifier and want to build in some simple speaker protection (Im not actually sure if a VFET would react the same way as a standard output transistor if the speaker leads were shorted). thanks
Trnsfmr
Well-Known Member
A good way to look at is to take the rail voltage, say 46 volts or so for a typical 60-70 wpc amp and divide it by the speaker impedance. If the output should go to rail, you want the fuse to blow instantly.
So... 46v/ 7.2ohm= 6.38Amp. A 3A or 4A fuse would go very quickly. You also might want to just start with 3 amp fuses and see if you ever blow them in normal op. If you do, go a little higher.
On Justin's workbench, he has all 4 speakers fused with 1A fuses. He blows one pretty often. His speakers will play amazingly loud with the 1A fuses. But the slightest problem when turning on a rebuilt amp or setting bias, etc. and, 'zap'... they're gone. He has those in line fuse holders, and when they blow they make little flashes of light, always accompanied by an "ooops" and a chuckle. I have 2A's in mine, but I usually am not doing 1st power ups, or setting bias.
You can buy fuses at Allelectronics.com for $0.15. We of course, have a lot of fuses in the parts rack. They also have the inline fuseholders, cheap.
KingBubba
"Too Much Stuff"
As my Model eight ages, it has had some issues with occasional spikes. I will replace it with the G-8000 soon. In the meantime the non relay protection has kicked in and done its job; silently but effectively so far. I do think the relay version would be preferable, but beggars can't be choosy. I found this eight on CL many years ago and have never seen another regular Eight since.
Integra88
New Member
Thank you for this very valuable advice. I just acquired an Eight from the son of the original owner. I am planning on having it serviced. Any advice ?
