I just love big, old power amps! And now I'm considering buying a model 4000 Threshold amp that is for sale. The look of this class A amp is fantastic, I can imagine the sound is too. But, there is very little information on the specs on this amp. My biggest concern is how well it can handle low impedance loads, since I will be using it on a pair Infinity Kappa 9.2i speakers.
Anyone here have some info on this amp?
Anyone here have some info on this amp?
A quick google search led to this very interesting blast-from-the-past article. https://www.stereophile.com/interviews/1191pass/index.html
But, otherwise, I am of no help to the OP's query.
But, otherwise, I am of no help to the OP's query.
Nice, good reading. Looks like everything is here.
But still no info on impedances below 8ohm.
Do any of you maybe have some first hand experience with this amp and know how well it handles 4 to 2ohm? And the what are the rating of filter caps?
But still no info on impedances below 8ohm.
Do any of you maybe have some first hand experience with this amp and know how well it handles 4 to 2ohm? And the what are the rating of filter caps?
I know this has been asked several times over the years but could really use some help.
After doing several searches, I can still only find some sporadic notes and some low res drawings, mostly hand written notes. I recently acquired a Threshold 4000 amp in need of some major work and quite a few transistors; A good friend of mine who does vintage audio repair is willing to help me (volunteer time) get it working again but is asking if I can find any good readable schematics, parts list and values to help eliminate some of the guess work and save a lot of time to getting it back in working order.
If anyone can provide any service documents & useful schematics for the 4000 that can help for diagnosing and speed up repairs to get it back to it's original design and parts will be greatly appreciated. I would love to save this amp and having it playing sweet music as it was originally intended to.
Thanks in advance
Pics of my amp
After doing several searches, I can still only find some sporadic notes and some low res drawings, mostly hand written notes. I recently acquired a Threshold 4000 amp in need of some major work and quite a few transistors; A good friend of mine who does vintage audio repair is willing to help me (volunteer time) get it working again but is asking if I can find any good readable schematics, parts list and values to help eliminate some of the guess work and save a lot of time to getting it back in working order.
If anyone can provide any service documents & useful schematics for the 4000 that can help for diagnosing and speed up repairs to get it back to it's original design and parts will be greatly appreciated. I would love to save this amp and having it playing sweet music as it was originally intended to.
Thanks in advance
Pics of my amp
Attachments
Just checking in to see if anyone has the schematic for the 4000 or can help with the parts list. I have one of these sitting at my tech's shop collecting dust because he can't find the info he needs. Thanks
One just popped up by me, is it something I should consider? Anyone know where I could send it to be refurbished?