Threshold 400A Amplifier and Conrad Jonson MF2500A


Hi members. I need some opinions on a Threshold 400A  wich I got 2 days ago for a reasonable price. The Amp sound amazing but it gets really warm. Should I leave it  on all the time or turn it off every night? your advice will be appreciated. Thanks Osiris.
osirir
The 400A is a Class A amp, so yeah, it runs hot and should.

I have a pair of Class A mono amps that run really hot and sound better the hotter they get.  

IMHO, you should always leave Class A amps on 24/7.  That provides the thermal stabilization that they require to work and sound best. Only turn them off, if you're going to be gone for an extended period of time.

I've owned several different Class A amps and they have all behaved the best when left on all the time.  My favorite amps are Class A, just a personal preference, but they sound the best to me.

Thanks for your advice, I will leave it on all the time. So the temperature does not affect  the live span of internal parts?  
There are two sides to that question. IMHO turning it on and off is worse than leaving it on all the time, but some others will argue with that.  The in-rush of current, stresses the internal components when the piece of gear is turned on and off, (unless the equipment has a "slow start" circuit).

Class A amps do run hot and depending on where you live and the season, they can sometimes force you out of the room. Also, if electricity is expensive where you live, that’s another concern.

Over my many years in the audio biz, I’ve found that leaving SOLID STATE gear on all the time, stabilizes and reduces wear and tear and makes them last longer.

With tube gear, I always turn it off to keep from replacing tubes so often, which can be expensive depending on the type of tube.

Maybe Al, (Almarg) will chime in on this subject. He’s our resident electrical expert and I’m sure has stated a few times his feelings, but I can’t find any of his comments about this subject right now.

YMMV...
Hi Osirir

IME don't plug the Threshold 400A into any kind of power conditioner. I remember I plugged it into a 1.8Kva Isolation transformer & when I turned the 400A on the isolation transformers started humming even louder. After that it went straight into the wall.

Now I didn't leave it on all the time. Electricity by me is expensive. What I had to do to get the amp sounding right was leaving the amp on for 10-12 hours before a listening session. I would turn it on in the morning before work and when I got home after doing some chores in the evening I would start my listening session then. The music sounded real sweet.


Thanks for your wonderful advice. It makes me feel good to be a member when you get honest and useful  response from beautiful people. Thanks Again. Chears  
osirir just curious why does the title of your post mention the Conrad-johnson MF2500A?
Yes indeed. The CJ 2500a is a fine amplifier!
I'd be a little paranoid leaving the 400A on all of the time.  I had one and loved it.  The energy waste is huge so I only left it on if I was going to listen again in the near future. 
Why paranoid?  This is a fairly old unit and it well known that when they fail it can be catastrophic.  If they fry, it won't just be one transformer but most likely a whole bank of 8...
Use a surge protector if you aren't using a conditioner.  Also, have a tech check it out before leaving it on all the time.
Hi Jond. The reason was because I have a CJ MF2500 upgrade to A version and I was comparing it with the Threshold 400A. I love the MF2500, it is a sweet Amp. Chears
Hi Elevick. Yes that is exactly how I feel : paranoid: I'm using a Audioprism Mantissa power conditioner. I just got the 400A  and the previous owner had a full revision done in 2013. It is a great Amp. Is there any way to find out when it was build?. Thanks for your response. Osiris 
I concur w/ the panel- an amp like this does not plug into any line/power conditioner.
I turn amps on a couple hours prior to listening. I dont find many hours necessary for getting them up to good running temperature. But as pointed out keeping amps on cuts back on the wear and tear.

Keep in mind you while leaving amps on you also risk damage if a bad electrical storm passes through while your not close and able to unplug electronics. I live in a region where electrical storms are common from about may into September so only do I power everything down I take the extra measure and unplug electronics for the insurance.  
Hi jafant. What would be the benefit of not using a power conditioner on the 400A and the negative of using one?. Thanks Osiris
Right at this moment I,m listening to the 400A plug directly to the wall no power conditioner. The top end of this amplifier is out of the world. Threshold 400A blue circle BC3 Despina Tube PreAmp Audiolab MDAC with ATC SCM 11 V2 Thanks for the advice guys. The power conditioner does not improve the 400A. This is a gem of  an amplifier. 
I'll admit I'm a c-j fanboy, but that Threshold is a killer amp.....enjoy
Glad to hear you like it, those are butt kicking good. Looks and sound wise. I think any amp will sound at its best directly into the wall outlet and nothing breaking there communion. Reserve the filter plug ins for other sensitive electronics like your multiplayer/ cable box/ laptop and so.

I'm in a pinch for time I have a reference saved somewhere, it has lots of info and pretty pictures of past Pass designs of the era I will have to locate that one. 
No conditioner can be risky.  At least use some sort of surge protector or UPS.  I have a whole house surge protector (only trips on big hits).  Additionally, I have PS Audio & Blue Circle conditioners throughout the house.  We had lightning hit a transformer a few years back, it tripped the house surge, it totally fried one of my PS Audio pieces (Dectet), which in turn saved about $10k worth of gear plugged into it.
Would I go straight into an outlet???  Never, especially with something like a 400A which is amazing, impossible to replace and would be too expensive to repair if you do have a power surge.