Hi, I am new to the forum here but have been collecting vintage audio for many years. I purchased a Threshold CAS 2 power amp and SL10 preamp at a garage sale this weekend. I am not sure the last time either of these were used and I was concerned to power up the amp. I do own a variac but have never used it. It is basic and just has a dial to adjust the voltage. Should I power the amp up with the variac or not. If yes, can someone advise how to go about it. I ordered a preowned power supply for the preamp as it was missing so I will wait to ask about that. I have some skill but do not want to damage the amp as I have read this is a beautiful setup. Also, if anyone has schematics for either of these, that would be great as well. Thanks in advance.
How y'all doing?
I found this doing a search: Threshold Amplifier - Overview and Schematic Collection of all Models
There might be a schematic...
Also, regarding the question about the variac- it's pretty easy, you plug the amp into the variac, turn the knob up to 120 Vac. It's a good idea to use a dim bulb tester. I suggest you do a search and some reading about it on this here forum. Also, now you will get some more replies.
I found this doing a search: Threshold Amplifier - Overview and Schematic Collection of all Models
There might be a schematic...
Also, regarding the question about the variac- it's pretty easy, you plug the amp into the variac, turn the knob up to 120 Vac. It's a good idea to use a dim bulb tester. I suggest you do a search and some reading about it on this here forum. Also, now you will get some more replies.
Here's a preamp power supply on sale for a good price:
https://www.ebay.com/i/143707411122...1291&msclkid=85723cebf9ac110e29a06365d6273f3b
https://www.ebay.com/i/143707411122...1291&msclkid=85723cebf9ac110e29a06365d6273f3b
Thanks for the response! I actually purchased the power supply for the preamp already. I am familiar with a dim bulb tester. Are you suggesting to use that instead of the variac or together with the variac? How slowly does one typically turn up the voltage on the variac?
I will look.into that link you sent me! Thanks again!
I will look.into that link you sent me! Thanks again!
If you use the Variac, test it first alone with a DVM reading the output,
to be sure you won't damage the amp. Depending on how it is connected,
it could put out up to 140VAC. Also make sure it has enough current output
to run the amp, or the Variac itself will be permanently damaged if it is not fused.
Start at 0VAC, and slowly turn it up over a period of several minutes or longer
(an hour is safer) until the Variac output is 120VAC. Do not go to 100,
this reading is not directly related to the output voltage. The Variac output should be
fused at or below the Variac's rated output current (not the amp's rated current).
to be sure you won't damage the amp. Depending on how it is connected,
it could put out up to 140VAC. Also make sure it has enough current output
to run the amp, or the Variac itself will be permanently damaged if it is not fused.
Start at 0VAC, and slowly turn it up over a period of several minutes or longer
(an hour is safer) until the Variac output is 120VAC. Do not go to 100,
this reading is not directly related to the output voltage. The Variac output should be
fused at or below the Variac's rated output current (not the amp's rated current).
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I really appreciate the help. Yes, I know my variac can output more than 120vac so I will definitely test the voltage so I know what the output is. Thank you for that, I did not actually think of doing that beforehand. I have to check the rating on both the amp and variac to.makensure the variac will handle the amp. This will probably be a weekend project for me. I will post back when I have more information. Thanks again!