Like

NAD T753 cooling fan question

 

Anonymous
 
Picked up an NAD T753. I had heard that the cooling subsystem had been reworked. On the earlier model (T752) I'd heard that the fan was a bit loud when it came on. I was surprised to find the that fan on the T753 started immediately when the unit was first powered up and stayed on thereafter. Great sounding A/V amp, though I am a bit disappointed I hear the fan during moments of silence. It's not that loud, but it can still be heard.

Anyone know if this is the normal behavior for the T753?
 

Bronze Member
Username: Paul_t

Post Number: 52
Registered: 12-2003
I've never heard the fan on my T752..
 

Anonymous
 
Yes, the fans (4 of them on the bottom)come on the moment the unit is powered on and run continuously until you turn off the NAD.
 

Bronze Member
Username: Paul_t

Post Number: 53
Registered: 12-2003
Again I never heard them, I just put my ear to the top of my T752 and turned it on and can't hear a thing.. I must be lucky and have a very quiet fan...
 

Anonymous
 
Sorry for the confusion. From my previous post, the 4 fans are on my T753.
 

bi0hazard
Unregistered guest
Paul T: same here, never heard the fan came on on my T752. When I passed it on to my dad (moved on to tubes) he commented (after some use) that it might be broken because he's never heard the fan come on hehe
 

Anonymous
 
I need to refine my initial posting that started this thread. I have "new" information. In fairness to NAD, I discovered yesterday that the noise I was hearing was actually coming from two sources and the fan was not dominant. Yes, the fan(s) on the T753 are comming on immediately but their contribution to the noise is small. Again, the noise in total is relatively small too, but I don't want to hear anything when the source says that there is recorded silence. The culprit now appears to be a quiet whine heard when listening to a CD via a DVD/CD player w/ digital connection to the NAD and processed through a non-stereo surround mode. The whine level is constant regardless of volume setting unless it is set to the lowest possible setting or put on mute, at which time the surrounds are quite silent. Is it my digital interconnect between the DVD/CD player and the NAD? Is it the processor? Not sure yet. More investigation to come....
 

Bronze Member
Username: Goose

Post Number: 23
Registered: 01-2004
Sounds like the dreaded NAD hum ... check out the thread on this a ways down.
 

Bronze Member
Username: Billdashill

Post Number: 51
Registered: 12-2003
What are you gonna do, when NAD whines on you!?!?!

Looks like NAD is sinking fast. Funny thing I haven't heard these issues with NAD's integrated amps I wonder if the NAD amps are built in a different factory. I am strongly leaning towards getting a NAD C352 whwn I get the funds that is.
 

Anonymous
 
I received a forwarded e-mail from NAD describing the fan function. They redesigned it to run continuously at slow speed so that there was less of a need for higher (and louder) operation later. The explaination makes sense, including the design tradeoffs. And, as I noted yesterday, I now realize the fan noise is negligible. The low volume humm/whine on the other hand is what I am hearing the most.

I'm trying now determine if it is due to the amp or something in how my transport is connected. I only hear the noise on the rear surrounds when a relevant mode is active. Downmix and and Stereo do not engage the rears, so the hummm is gone.
 

Bronze Member
Username: Larsa

Post Number: 21
Registered: 01-2004
You could try doing a reset?
Follow Chris Astolfo's advice in https://www.ecoustics.com/electronics/forum/home-audio/10321.html
 

Anonymous
 
Did that and more. Check out the thread https://www.ecoustics.com/electronics/forum/home-audio/9750.html. I didn't say it there (yet) but I tried the Video 6 + Source<(c> (AH? Reset) with no change. The humm is present if I have a digital coax source and all other menu items OFF. Next step I think is to take it to the dealer and set it up there to rule out that it is an interconnect/transport/power problem.
 

New member
Username: Rob

Post Number: 1
Registered: 02-2004
I was interested by the claim of a 'noisy' fan on the T753. My story with NAD is the following: I bought a T752 with a T532 DVD/CD player in march '03. After two weeks the volume didn't work and I got a new one. The second T752 had a disturbant humming, probably the transformator gave some vibration on the case. I gave it back to the dealer and I got a third T752. But also this one hampered after two weeks with the volume. You can imagine I was very disappointed because the sound of NAD is really fantastic.
I told the dealer to give back my money or to deliver a T753. Again a perfect sound, also in combination with the NAD DVD/CD player (optical connection, no hum/whine sound). But now is the problem.... do I have to accept the sound of the fan ?? This sound is indeed neglible at a distance of 1 meter from the T753 with the volume at 60 dB, playing music. During silent moments in a film or on a CD you can hear the fan running. Who has also this experience? Again, the sound of NAD is really perfect, the sound of the fan is at some moments disturbing.
 

Anonymous
 
The explanation I received from NAD via my dealer rep was that on the 753, they redesigned the fans to run continuously at low speed. This is in contrast to the T752 which didn't turn on the fans until they were needed. When the did come on, they were at high speed and could readily be heard during silent or lesser dynamic moments (that's my limited experience. I only had a 752 for a few weeks).

It is a design tradeoff. No fans except when needed and then the sound is a good bit more noticeable (i.e., the 752) vs a quiet low-speed fan running continuously with less of a need for running faster and louder.

This design tradeoff makes sense to me. I don't know everything done under the hood to go from the 752 to the 753, but the sum total added an additional 10 lbs to its weight. I can easily imagine a need to dissipate more heat. If true, I'd much rather have the lower speed fans than higher velocity and louder fans since the latter would need to be on more often. That's my opinion.
 

Bronze Member
Username: Billdashill

Post Number: 52
Registered: 12-2003
How about designing a NAD receiver without the need for fans, period. That would get my attention! LOL The use of fans is a product of bad design IMHO.
 

New member
Username: Bigfan

Post Number: 10
Registered: 01-2004
I believe HK 7200 uses heat sinks and no fans. Do any other makers do this? If not, why is that?
 

Bronze Member
Username: Larsa

Post Number: 23
Registered: 01-2004
I can also hear the slight whirring of the T753 fan(s) from my listening position when there's no sound and the cabinet doors are open. If I close the tinted glass doors of the cabinet though, I'm not able to hear it. The cabinet is completely open on the back side, so there should be no airing problems.
 

New member
Username: Gatt767

Post Number: 8
Registered: 01-2004
From my T762 I can hear the hum of the fans spinning, but only when the volume is set to 0, I really do not hear any fan noise when viewing any films. I think we are being too critical with NAD.
 

Bronze Member
Username: Billdashill

Post Number: 54
Registered: 12-2003
bigfan, yes some Onkyo's and some Pioneer Elites and I believe some Marantz's also use massive heat sinks and proper design for cooling. I've been doing alot of research on this and I still cannot figure out why they all just elimiinate the cooling fans period. It might be that they use cheaper electronics and design it so only a fan will suffice cooling down the unit. I am against this as you know.
 

Silver Member
Username: Hawk

Post Number: 252
Registered: 12-2003
I got my 753 yesterday and after several hours of listening, I was never aware of the fans (there are four).

Jeff:

It is just the opposite. The NAD isn't using fans because of cheap electronics. The fans are needed because the amp is heavily biased toward Class A amplification which runs hotter, but give a much cleaner, smoother signal. Class A is what is used in quality separates. Also, my 753 weighs 45 lbs., so it is fair to say it has massive heat sinks, as well. These fans are just not a big deal (they are on the bottom of the receiver, after all).
 

Bronze Member
Username: Johnny

Post Number: 82
Registered: 12-2003
Hawk,

A quick question if you will. Your discussion on this thread got me wondering, so I started comparing some of the specs of NAD receivers. As you probably know, I am a proud T762 owner. I was wondering if you could explain why the T763 is so much heavier than the 762 (45.5lbs vs. 36.5lbs)? ON PAPER, they seem to be very similar...so why the nearly 25% jump in power between the two? I assume that it is some difference in internal components, but I am not privied to a list of these components (which you seem to be). Also, you mention that the 753 has "Class A" amplification. Does the 762 have this? I am just trying to "educate" myself a little and learn more about what I have.

Thanks!
 

New member
Username: Gatt767

Post Number: 9
Registered: 01-2004
It seems that the power amps in the T763 are a little bit more powerful than the T762. The T763 will give more wattage at lower loads as compared to the T762. As regards to the Fan Structure within these products, Fans doesn't mean lower quality components! Where other designs will shut down when pushed hard due to heat build up, NAD has installed its receivers with Fans to keep its internal power amps cool, therefore the components within do not suffer immature failures and shutdowns when driving speakers with low ohm age at reference level for a long period of time. Several high grade receivers are installed with Fans for example Onkyo, Arcam Etc. and all have there design as how to operate these fans. NAd has always opted for Fans, for example the T760, T751, T752, T761 all use a Fan to deal with heat probs. Do remember that the internals of a receiver, especially with these specs are extremely crammed, therefore heat sinks must be very efficient in dissipating heat plus Space is always at premium as other components need to be installed. Look at Harman Kardon; its receivers do not use any fans, especially the top of the range, which do come close to class A amplification. Its receivers are massive in size and weight as most of the internals are taken with very high efficient Heat sinks to keep heat levels down. As one knows, NAD has always kept to its promises, therefore if it says that a receiver will pump 100 watts * 6 at any load, then that output will be reached with a very minimum amount of distortion. So to offer that kind of performance in a very limited amount of space, shared with other components within the current chassis NAD had to install FANS to keep the internals at a very low Temp. This design also helped in keeping its chassis small plus a particular chassis of one model can be used for other models within the Range, therefore keeping costs down!
 

Silver Member
Username: Hawk

Post Number: 260
Registered: 12-2003
Johnny:

No, I can't be sure why the new models are so much heavier. I was totally surprised when I picked up the box with my new 753 yesterday--my first thought was "I'm toast." I figured I was either going to throw out my back or develop a hernia. Your observation is correct that they weigh significantly more than the 7x2 models, which tended to be heavier than the competition already. At the time I ordered it, I had not checked its dimensions and weight--I just figured it was just like the 752, so I was not prepared to lift it. I know my wife is going to have a cow when she sees it--it is significantly bigger than the unit she thought we were getting.

The biggest source of weight in a HT receiver is the heat sink--usually a large block of solid aluminum with fins cut into it to dissipate the heat generated by the output transistors. Now, I do know my 753 added a sixth channel to make it 6.1, so that also adds some weight, but as I haven't opened it up yet (my usual source for knowing what's inside), I can't be sure. I just know that the NAD website talks about revisions to the architecture made to make the unit run cooler, and the two additional fans simply don't add much weight, so I am guessing it is mostly the heat sink. Now, they may have also added more output transistors, as well, but I can't be sure. Another possibility is that they went to heavier circuit boards (6 layer instead of three or four), which would increase its reliability and longevity. I suspect it is a combination of all of these possibilities as one change is not likely to add that much weight by itself.

As far as the amplification goes, almost all of these transistor receivers have an archetecture that's called Class AB amplification. Class AB is a hybrid of true Class A and Class B, either of which has advantages and disadvantages. By making a hybrid, manufacturers are trying to get the best of both worlds. In executing this hybrid, manufacturers can "bias", that is tilt, their product towards one or the other (A or B) in the architecture. Generally speaking, Class A sounds better--cleaner and warmer, and much more lively sounding in my experience, but the amp can get really hot. This is why most receivers, and even many power amps, are not built in true Class A architecture as this heat can really shorten the life of the product and impair its reliability (I have known some true Class A amps that can actually heat a good sized room). Additionally, many consumers get pretty wary of something running hot--there is a consumer acceptance issue here (see the many posts we have had on this site about receivers running hot). Nevertheless, many separate pre-amps are built in a true Class A configuration because it is so clean sounding. Conversely, I auditioned a Marantz integrated amp a month or so ago and it was clearly biased heavily to the Class B end. Despite a high power rating, it ran cool enough that it was never hot to the touch (barely warm), even after hours of use. It hit every note exactly right and did absolutely nothing wrong--but it wasn't enjoyable to listen to, either. I found it rather boring, in fact. It is the perfect product for those people who don't believe there is any differences in the sound made by different amps. Homogenized is a great description, I think.

Your 762 follows the NAD tradition of tilting toward Class A. Not a true Class A, but heavily biased toward Class A, nevertheless. I think that accounts for the clean, warm sound that I truly enjoy. I know John A. has experienced the same thing with his T760, a full two generations before your product. He clearly has a critical ear and yet has been thoroughly satisfied by what I think is the NAD emphasis on getting the sound to be right and engaging. I think this is the converse of most of the mass market receiver makers who seem more interested in squeezing out another 0.01% of distortion (which none of us can hear, anyways). Heck, if I had had my money before Saturday Audio ran out of them, I would have a 762 myself, and been thrilled to have it.

One more observation. I have gone back and looked at what has been happening with the NAD product line and I think it has benefitted greatly from their being acquired by the Lenbrook Group (owners of PSB loudspeakers). I think NAD had lost its way as an audio company during the 1990s while they were owned by that Scandanavian conglomerate (I have forgotten the name). I know they never interested me in the least and it was even a little difficult for me to even find them in California where I lived. Lenbrook bought them four years ago and every generation they have brought out seems better and better--the sound quality remains, but the buiild quality improves. My first impression of my 753 is that their build quality now is in the same class as H/K and Pioneer Elite, which I have long felt were the top of the industry, build wise. I am thrilled with my new receiver and expect I will be spending some time looking at other components to go with it, like DVD players. The new T542, with DVD-Audio may suddenly be on my Christmas list, if I can wait that long!

Cheers!
 

New member
Username: Gatt767

Post Number: 10
Registered: 01-2004
These are nads rating for the T762
180W, 230W, 260W, IHF Dynamic Power into 8, 4 and 2 ohms, respectively
The following are for the T763
210W, 300W, 370W IHF Dynamic Power into 8, 4 and 2 ohms, respectively
Definitly more power for the T763, it explains why it is more heavier. A Larger Toroidal Power Transformer and maybe a larger heatsink
 

Bronze Member
Username: Gatt767

Post Number: 11
Registered: 01-2004
By the way these are the internals of a T762 to make myself more clear regarding the internal space of these receiversNAD.jpg
 

Bronze Member
Username: Billdashill

Post Number: 55
Registered: 12-2003
Thats ridiculous. Thats why I'm staying with a 2 channel NAD integrated as my choice. C352 or C372 if I'm able to.
 

Bronze Member
Username: Johnny

Post Number: 84
Registered: 12-2003
Hawk, Robert:

Thanks a lot for all of the info...I really appreciate it! I obviously don't like the fact that the "new guy" has more power than my 762, but I guess that is what happens in the world of electronics. I seriously doubt I would ever need all of the power of either. Heck, if I ever do, it will give me an excuse to pester the wife into letting me buy an NAD T973 seven channel amp and use the 762 as a pre/pro. Now that thing is rediculous...it weighs 68 pounds!!! And that is just for the amp! I would need a forklift just to get it into the entertainment rack.
 

Silver Member
Username: John_a

Post Number: 184
Registered: 12-2003
Great photo, Robert.

It's just like my T760, except a few boards are mounted differently. I learned my way around from the service manual, having to replace some blown components on the AC3/DTS board (where the DSP is).

Hawk, I just want to say I had great service from AudioNord in Denmark, recently. They owned NAD before selling it to Lenbrook. They are still the Scandinavian distributor, really know what is what, and in fact introduced the Silver series. They are not at all a "conglomerate". If fact, they sold me a service manual, and a technical guy talked and e-mailed me through a component replacement. It felt like doing amateur brain surgery, but it worked. That is how consumer electronics should be. I got the impression from talking to the guy that they only sold to Lenbrook when they were convinced NAd would stay in safe hands. Which it is! Don't knock AudioNord!

BTW There are actually a number of heat sinks. The DTS/AC3 board has one. On my model the capacitors were only rated to 80 deg C, which was the probable cause of the failure, since they sat right next to a board heat sink. It caused hum in surround mode, BTW. On all newer models (T752 on) they are rated to 110 deg C and this T760 "known issue" is no longer known.

The big aluminium heat sink in the middle is like air-cooling fins on an motorcycle engine. It can, and should, get hot as toast when the units works out - all the power amp stages are connected to it. Even so, it is not the heaviest single component, by far - aluminium is light. The heaviest thing is the big tordoidal transformer to the left. It is a beut. It is soldered in with like an electricity substation. Rock solid. That is half the beauty of NAD, they do not skimp on power supply. The transformer is not a feature, like "bordello surround effect" or whatever it is. It just delivers the goods. I urge people to take off the covers and see what you bought (with unit disconnected, of course). A medium cross-point screwdriver is all you need.
« Previous Thread | Next Thread »

Facebook

Shop Related Deals

Directory

Main Forums

Today's Posts

Forum Help

Follow Us