Amplifier warm up...

jaxwired

Well-known member
Feb 7, 2009
284
6
18,895
I've always been a semi-skeptic about amplifier warm up and I'm still a semi-skeptic. However, here's what I'm experiencing. Mostly these days I listen to headphones, but I also get a chance to listen to my PMC DB1is on occassion. I'm powering them with a NAD C316bee 40w/ch amp. The amp stays fully off when not in use. Meaning I turn it off on the back switch, not standby. I do this because the speakers are not left connected and I worry about the speaker wires touching each other and shorting out the amp. So when I get a chance to listen to the PMCs with the NAD amp, I've consistenly had the same experience every time. At first listen I always think the PMCs sound muddy. Both the bass and the mids. And the treble lacks sparkle. Overall, completely unimpressive. In fact, I usually think to myself, "self...I should sell these PMCs and buy something else." BUT, after about 15 minutes of play time, I've not only reversed this position, I'm so impressed with PMCs, I'm wondering if I should replace my large Dyn speakers with more expensive PMCs because they sound so fantastic. Stringed instruments are particularly impressive, but overall presentation is a joy to hear with lots of sparkle and a clean clear live sound to everything.

So, it could be my imagination. That's what I chalked it up to the first few times, but now I've realized this happens everytime I play the PMC/NAD combo. It's a consistent experience. It could be the amp needs warm up. Or it could be even the speakers need warm up. Not sure what's going on here...
 

bladeslap

New member
Jun 17, 2008
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In my experience both amp and speakers and everything else need warming up to produce their best.

I tend to switch on half an hour before listening...and in the days of lower fuel bills I kept the amps on at all times.
 
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Anonymous

Guest
there are many things Hi Fi I am sceptical about, however, In my experience amps work their best when fully warmed up. I used to own the Monitor Audio Br2's and found that they really started to shine after about an hour and a half. I even phoned MA to ask than about this. Ok so it could be in my head, ( maybe I am more relaxed after that amount of time listening to great tunes). I did some research and in conjuction with another forum user discovered that the tweeters in MA Bronze collection do infact change character when the drivers are warmed up. If I find the right link a will post it.
 
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Anonymous

Guest
I would like to add that when rehearsing we used to experience a dramatic change in sound quality after the room had warmed up.

Follow this link and scroll down to

Temperature and Humidity Effects on the Speed of Sound.

http://www.rane.com/pdf/ranenotes/Enviromental%20Effects%20on%20the%20Speed%20of%20Sound.pdf
 
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Anonymous

Guest
I know it's a simplistic view but imagine the massive change in sonic properties of a concert hall empty compared to the same one filled with 5000 sweaty humans.

In fact when rehearsing a large symphony orchestra it's wise to take into account that the halls sonic properties will change dramatically during the actual concert( if sold out) due to the amount of people in the hall. In fact in choral music in can impact a great deal on the reverb/ delay of the building and thus change the performance compared to how it sounded in rehearsal. Good musicians can adapt quickly to this change and still put on a superb performance. Of course it can go the other way. I have heard a choir brake down during a performance due to underestimating the change in delay of the building from the rehearsal.
 

simon3102000

New member
Oct 1, 2010
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I find my headphones take 10mins or so to get at their potential... But my wharfdales sound awsome from the get go!!! All my amp, cd player etc is left on standby so im sure this keeps the circuitry warm for when you use it????
 
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Anonymous

Guest
I am sure someone can correct me if I am wrong

but 10 fahrenheit change in a rooms temp cause a 1% change in the speed of sound through air. Whilst a change of humidity in a room from 1% to 100% will cause a 0.1 % change in the speed of sou d through air.

So turning the central heating on will have a more dramatic change on the speed of sound through air compared to boiling a pan of water in the kitchen will do. or will it as

humidity affects absorption which could impact the qualities of high frequencies in a room.

Which is a very good reason why Hi fi should always be auditioned in the home. I guess it's no surprise therefore that two identical Hi fi set ups can sound entirely different in different rooms

Auditioning over a long period is really the only way to be sure.
 
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Anonymous

Guest
And I guess to keep some consistency I am sure that What Hi Fi try and keep the same ambient temperature of their listening rooms when conducting each review.
 
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Anonymous

Guest
brittondave:........ when rehearsing a large symphony orchestra it's wise to take into account that the halls sonic properties will change dramatically during the actual concert.............

+1 for this observation ^^^^^

It's not just classical music that this applies to either.

I have worked with enough top rock bands to know that there is such a difference in sound between an empty hall, theater or arena and one filled to capacity, that rehearsing is a pointless exercise except for reasons of acclimatisation, ensuring PA system and monitors wired up correctly, and stage lighting focus.

As far as sound balancing and volume settings are concerned, as i said, it's pointless as the changes are so great.

The prime reason for top rock bands rehearsing is to enable a quick visit to the tour caterers to avoid having to eat hotel food !
 
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Anonymous

Guest
willieeckslyke:
brittondave:........ when rehearsing a large symphony orchestra it's wise to take into account that the halls sonic properties will change dramatically during the actual concert.............

+1 for this observation ^^^^^

It's not just classical music that this applies to either.

I have worked with enough top rock bands to know that there is such a difference in sound between an empty hall, theater or arena and one filled to capacity, that rehearsing is a pointless exercise except for reasons of acclimatisation, ensuring PA system and monitors wired up correctly, and stage lighting focus.

As far as sound balancing and volume settings are concerned, as i said, it's pointless as the changes are so great.

The prime reason for top rock bands rehearsing is to enable a quick visit to the tour caterers to avoid having to eat hotel food !

Indeed! " Eat to the Beat " are responsible for some of my favorite dinners ever. and it takes some serious will power to stay away from the cheese board at lunch.
 

jaxwired

Well-known member
Feb 7, 2009
284
6
18,895
Cypher:

Jaxwired,

has the C316bee enough power to drive the PMC's ?

Well, it does sound shockingly good once the warm up completes. Would they sound better with 300 watts of Bryston gear? Guaranteed. But I think most people would be surprised how good the PMCs do sound with this little NAD driving them. And of course NAD amps have "power drive" with quite a bit of dynamic power available for short bursts.
 

Blackdawn

Well-known member
May 7, 2010
88
1
18,545
Very intersting. In comparison with the 316BEE, the 3020A sounded really good from cold. Again could be a room thing.

Anyway, very intersting to read that Jax found the NAD to sound really good with his higher end speakers. Makes we think speakers and source are still good places to put your money as apposed to purchasing a really expensive amp with moderate speakers.
 

idc

Well-known member
Jan 2, 2008
1,113
67
19,270
I think that there is no doubt to amp and speaker warm up, with amps it really is getting to running temperature and with speakers it is running in the cones.

I prefer my amp with its cold sound, so it is well ventilated.
 

audioaffair

New member
Feb 21, 2009
100
0
0
There is some science to this, especially if your hi-fi has been off for a while and capacitors saturate after being turned on. The effects are arguably greater with valve amps as letting them warm before conducing can extend their life in hours and protects cathodes from damage - similar in principle to letting a car engine warm up before driving.

I'm surprised in some respects many valve amps don't have a cut in option that stops the circuit being used (and mutes the signal) for a few moments before being able to be used - the only product I've used with something similar is the Pure Sound A8000 CD player with a valve output stage which has to warm up for 30 seconds before you can use it (and does a cool count down on the display). Having said that there are a few other amps (even far back as the Pioneer A400) that had a cut in period of about 5-10 seconds which isn't as great as it could be but is about all that some people might stand before complaining about the wait!
 

plastic penguin

Well-known member
brittondave:I am sure someone can correct me if I am wrong but 10 fahrenheit change in a rooms temp cause a 1% change in the speed of sound through air. Whilst a change of humidity in a room from 1% to 100% will cause a 0.1 % change in the speed of sou d through air. So turning the central heating on will have a more dramatic change on the speed of sound through air compared to boiling a pan of water in the kitchen will do. or will it as humidity affects absorption which could impact the qualities of high frequencies in a room. Which is a very good reason why Hi fi should always be auditioned in the home. I guess it's no surprise therefore that two identical Hi fi set ups can sound entirely different in different rooms Auditioning over a long period is really the only way to be sure.

I understand the thesis regards speakers but amps I'm not too sure. If an amp is spanking brand new then yes... like a car it needs running or bedding in, but if you just need to warm up an amp, not sure.
 
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Anonymous

Guest
well having just spent a lot of time with my amp and a multimeter i can say without any doubt that amplifiers will sound different as they warm up!
i have been adjusting the dc bias current on my a400. with my multi-meter attached to one of the resistors on the pcb to measure the amps i can see the measurement increase gradually from a cold start until it reaches its operating temp at which time the reading will peak and stabilise.
so what does this mean in terms of sound quality? well the factory setting for this amp was about 50 milli-amps. I now have it running near 200 milli-amps and the difference in sound quality is significant. The sound has bag loads more detail and drive!
I do realise that not all amps have the same design as mine but im sure that they will have a similar reaction as they warm up.
 
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Anonymous

Guest
im disappointed that no one has replied to my post. i thought laying down some cold hard facts would have been appreciated...
 

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