Super Tower power requirements...

Davidinvic · « **on:** 21 Apr 2006, 02:38 am »

I purchased from Brian a set of Super Towers with focal tweeters, mid-range ribbon , 10" mid bass, 15" woofer and 15" passive radiator (sp?) approximately three years ago. I lived in San Diego at the time. I've now relocated to Victoria, BC and am having a real tough time finding a "budget" amplifier to run them as my old Carver (300w per side) equipment fades. I believe I have just toasted a new NAD 372 with its 150wpc output. According to Brian, the impedence of these marvelous speakers can be as low as 3.6 ohms. Any brand/model suggestions? Trying to keep costs reasonable as we just had twins...and audio needs must for a bit take a back seat in the list of priorities. Thank you.

john1970 · « **Reply #1 on:** 21 Apr 2006, 03:32 am »

You might want to try a used Adcom amp and use the NAD as a preamp if at all possible. I am amazed that you damaged a NAD C372. I am currently using that exact amp to drive a pair of RM40s in a 14' x 25' x 8' (W x L x H) living room. At a 9' listening distance I can drive the speaker easily to 95 dB peaks without any problems for an entire CD (Metallica S&M Disc 1). Once I had a problem when I left the doors of my hifi cabinet closed during listening to a movie and the amp did go into thermal protect mode. However, after the amp cooled down everything went back to normal.

Some questions to consider:

1) How is the airflow around the amp?

2) How large is your listening room?

3) How loud do you listen to music?

IMO you will need a larger amp if you do farfield listening in a large room. Lastly, a larger amp will give slightly better bass and I do mean slightly (based on my comparison between my NAD C372 and a Bryston 4BSST driving a pair of RM30Ms).

Good luck,

John

Davidinvic · « **Reply #2 on:** 21 Apr 2006, 04:36 am »

Thanks for the thoughts, John. The Nad is in a cabinet with no doors and 6" airspace above. It goes into thermal protection mode after about 1.5 hours regardless of the volume of the music. I will reconnect with it totally exposed on all sides and see what happens. I like the amp...and a fair value for the money. And it even has tone controls which are currently out of favor. I am concerned that with moderate listening levels it may have a very short lifespan as it does seem to generate a substantial amount of heat and the manual has all sorts of warnings about not running spaeakers below 4 ohms.

john1970 · « **Reply #3 on:** 21 Apr 2006, 09:50 am »

A few additional points:

1) I've used the amp for listening to music for ~2 hours straight with no problems at moderate listening levels (80-90 dB 9' from the speaker). I admit it does get warm, but does not go into thermal protect mode. If in a cabinet try to install a small cooling fan.

2) Remeber that when an amplifier specifies a minimum 4 ohm load that the spec is refering to a nominal (average) impedence. Many 4 ohm speakers have dips that are well below 3.6 ohms. I am still having difficulty believing that the NAD is going into thermal protect mode. NAD does specify a dynamic power into a 2 ohm load which suggests that it can handle temporary dips into the 2 ohm region.

3) You might want to ask NAD directly at their website. Although I've found that getting a reply takes a long time and the response is not always very useful.

http://www.nadelectronics.com/help/

4) In the worst-case-scenario use the NAD C372 as the preamp and a used Adcom GFA-555 MkII (used ~$500) as the main power amp.

Please let me know how it turn out,

John

flintstone · « **Reply #4 on:** 21 Apr 2006, 01:20 pm »

I've been driving mine with an Onkyo M-504 for 9 years...never a problem even at very high SPL's. Mine are part of an old VMPS surround sound system I bought new...still sounds great even after 9 years!

Dave

john1970 · « **Reply #5 on:** 22 Apr 2006, 01:59 pm »

Last night I increased the air space above the NAD C372 to ~ 7.5" from 4.5 inches I noticed that it does run substaintially cooler. I am looking for a quiet cooling method to cool the amp even further.

PLMONROE · « **Reply #6 on:** 22 Apr 2006, 03:49 pm »

You might try a super quiet computer fan above it. Even the slightest increase of air flow will do wonders.

Paul

Davidinvic · « **Reply #7 on:** 22 Apr 2006, 05:05 pm »

At Nad's suggestion, I returned the amp and exchanged it for another...New Nad has run for 18 hours straight with no shutdown. Guess the first unit was a little oversensitive. Both dealer and Nad believe the amp can power the speakers...and at 11o'clock on the volume, the sound levels are about as loud as I would likely go. Sound is good, although a touch less bass than my Carver 300wpc produced. Will keep testing and I will try it once again back in the cabinet with at least 6 inches of airspace on the tp. As suggested, a little computer fan may be necessary. Appreciate the suggestions.

John Casler · « **Reply #8 on:** 22 Apr 2006, 07:34 pm »

If you run into the problem again, I have found Active Thermal Management's products to be helpful, and reasonable.

http://www.activethermal.com/Cool-Shelf.htm

Davidinvic · « **Reply #9 on:** 22 Apr 2006, 08:04 pm »

A great suggestion! I will check on their pricing.