Multi-channel amplifier for Theos

[edwinr]

After reading the 'Aerius bi amping or bridging ?..' thread which I posted in, I decided to give the T777 another go, so I pulled the receiver out and carefully examined the NAD's speaker binding posts (which I criticized early). I noticed that the NAD's binding posts don't give a very secure connection unless they are tightened VERY firmly. These terminals are deceptive, when they initially feel secure, they're not. You have to wiggle them a little so they tighten properly. So maybe insecure connections were causing the receiver to turn off when driven hard. Also the connection with banana plugs is quite loose. Mmmmm, poor design = possible problem here...

Solution?

This time I inserted QED silver anniversary cable using bare wire connections into my system. I used the QED cable because it's a little thinner than my standard Tara Labs cable and way more flexible. I took even more care than before, making sure the connections were very, very secure and that there was no stray wires. I wired for passive bi-amp mode. On switch on everything ran okay, so on with some serious listening. As I said in the other thread, I thought I heard some very subtle improvements in dynamics, and a little improvement in sound staging.

I'm not saying that more ability to drive 'difficult' speakers wouldn't go astray - but what a difference it makes when everything is connected properly. I still can't see the T777 staying though if it keeps switching off.

Shame on NAD for crippling what could be the best upper mid range av receiver on the market with cheap speaker terminals. Also their marketing is askew. They're suggesting that their receivers have more real world power than other brands - despite their advertised low power ratings in comparison to other similarly priced receivers. I am starting to think this is a con job. I also doubt whether I will ever buy another NAD product.

 

[edwinr]

The NAD experiment is over! After many, many weeks, NAD were unable to come up with a workable solution to their amplifier shutting down while driving electrostatics. They suggested I take the amplifier to a local technician who would under their direction, replace some resistors in the protection circuitry and; "...that might work".

I spoke to the local ML distributor who said (quite rightfully too!) if NAD can't sort their mess out then he wouldn't support any warranty claims if I plugged any 'butchered' NAD product into my speakers. I am very disappointed with NAD. I'll never buy their stuff again.

I have back traded the NAD T777 receiver and I've replaced it with a Denon AVR 3313ci receiver. A less expensive option but from plug in, what a difference! Instant (relatively) high quality sound, plenty of power, no switch off problems. I still prefer the looks of the NAD receivers. At the end of the day, however, if it doesn't deliver, it doesn't deserve to be in my system.

For smaller rooms, I can see the Denon AVR 3313ci being a very good recommendation for the Theos/Vista type Martin Logan speakers for those just starting off. I was surprised how musical the Denon sounds playing some audiophile SACD jazz recordings. The build quality is good, and the connectors are reasonable quality. The remote is a bit basic, but it does what it's supposed to. The Denon runs a lot hotter than the NAD receivers. The Denon provides an easy upgrade path, allowing owners to plug in separate power amplifiers via the full set of pre-outs provided. All in all, a good recommendation.

Next step - I'll pick up my custom tube monoblocs, plug them into my Denon and use it as a preamp/processor driving the surrounds only. I am now confident that the Denon will drive my Theos comfortably if I need to service or change power amplifiers in the future.

I'll post pics when I set the rest of my system up.

 

[Guitarist]

I just bought a Parasound A 51 5-channel amp--I can't get over how much better it sounds than my Sony receiver! More detail, better bass, far more warmth--it's simply more effortless and musical.

 

[Nielsen]

The Nad also has preout terminals for all channels....
Nad is one of the few companies (along with Harman Kardon) that state specs accurately, many of the other companies wildly exaggerate, some 100 watt receivers have been measured to around 30 watts only drivin a real load.
Here where I live the Denon cost half that of the Nad so if you say Denon is a better receiver than Nad I am really surprised.....
Many Martin Logans have a nearly short curcuit load in the high treble, my speakers have 1,3 ohm at 19.000 hz I think, and when you drive these speakers of for instance a digital design amplifier you will get no treble from the speaker at all. This load is probably also why the Nad shuts down at higher levels. Even though Nad is quite stable, my experience with Nad is that the sound is rather dark when they drive electrostatics.
Anyway, I would never dream of running Martin Logans from a mid priced home theater receiver....
Normally, when having a home theater and stereo, then you get a good integrated amp with a home theater loop, like the Bryston B-100 and a receiver with preout for the front channels. You then use the preouts to the integrateds home theater bypass input, attach the front speakers to the integrated, and connect all you stereo sources to the integrated amp.
Now you use the integrated just like any normal integrated amplifier, and when watching a movie the integrated will drive your main speakers. Just do a room correction setup with the receiver and you are ready for movies. Dont forget a subwoofer, its essential for movies since the LFE bass is a separate track on a movie.

 

[edwinr]

Thanks for your comments, Nielsen. I never said the Denon 'sounds better' than the NAD I made comments earlier that the new NAD receivers sound great. Problem is, the NAD receivers shut down when trying to drive Martin Logan speakers. From NAD themselves, they said their receivers should be able to drive a short circuit, and they recommended their T777 as suitable. They have since admitted there is a problem with their new receiver designs relating to electrostatics and other speakers that sometimes dip low in impedance. This is possibly in the protection circuitry itself. Their quick fix was unacceptable.

I thought it was a bit sad when a Denon receiver at nearly half the price could drive the Martin Logans to quite high levels without any shut down or other problems. At the end of the day many people cannot afford an initial spend on both something like a pair of Theos AND a high quality pre-power multi channel setup. A mid priced receiver with pre outs is a good option, leaving an upgrade path. I would definitely prefer the NAD range if it worked - but it didn't.

Nielsen, I like your setup. I was looking at the Bryston B100 myself as a future option. My B-60 was a real treasure and could drive the Theos quite well - but it's been sold to help pay for the tube mono blocs I have ordered.

Kind regards.

P.S. I note that the Theos will make any amplifier sound as good as that amplifier can, but it doesn't necessarily work the other way round. I can't wait to hear what the Theos will do with quality amplification.

 

[Nielsen]

I think you will be very happy with tubes on the Theos, although I think Bryston is better, always. Sorry, Bryston is my last amplifier I am sure, had it for 6 years now, and I havent thought about an "upgrade" even for a second, it does everything extremely well. Almost every day I play some quiet pianomusic after work and I am just floored by the texture, dynamics and awesome clarity it throws at me. For many years I would change amplifier once a year or so, always looking for the right thing and finally I feel free, at ease, home, you name it, wonderful feeling.
Just a hint, if you ever come across a used Coda amp at a good price, buy it! Here where I live they are very expensive, but I used to own a 10.5 power amplifier, sold it because I was going to build a home theater, I curse that day, must have been out of my mind. Anyway, Coda is extremely well built amplifiers, built by former Threshold employees. The 10.5 had 120.000uf, 16 output devices per channel and was build like a tank. I used it together with a Sonic Frontiers SFL-1 Signature preamp, those were the days....but back then I had fullrange electrostatics, the Audiostatic ES 100 DCI. My wife loved those speakers....ok, its time for me to go to bed now....

 

[edwinr]

Thanks and goodnight Nielsen. You make some great points about the need for quality amplification.

Guitarist, I've heard some good things about Parasound. The kind of things you're talking about regarding sound quality, is what I'm hoping to hear when I insert my new tube mono blocs into my system.

 

[Guitarist]

Guitarist, I've heard some good things about Parasound. The kind of things you're talking about regarding sound quality, is what I'm hoping to hear when I insert my new tube mono blocs into my system.

I thought about going the tube route, but coming up with a reasonably priced 5-channel system didn't seem to be possible! Parasound uses a mix of class A and AB--class A in a few critical areas of amplification, so the result is a more tube-like tone. I'm ecstatic, and I hope tubes make your speakers sing!