My initial impressions switching from Parasound Halo to an ATI AT524nc

[PENG]

Yes, but that's not as funny.
Buzz that I have heard is not 60Hz either.

- Rich

Naturally, like musical instruments, there will always be harmonics accompanied with the fundamental. Even birds can't do a single frequency pure tone.

 

[RichB]

No need, Dirac Live will fix it for you.., for the money it should everything, even if Shady says (he just might) not possible.

Yes, I understand that Dirac and other REQ fixes everything, if you run it enough times.
It is the ultimate objectivist methodology

- Rich

 

[PENG]

However unlikely, but I would not RULE OUT the part about "hearing sensitivity", so I would not call it BS.

It's not like anyone has done a massive scale double-blind research into this topic.

I agree the overall home electrical environment is the salient factor.

Interesting enough, someone on ASR just posted this:

"Long time Denon user, (despite the measurements and various advise on this forum) couldn't resist the deal for an openbox Arcam AVR20 for £2240 (new retails for £3199). First thing I noticed is 'transformer hum', may be not audible for average user but I certainly did (and family members once I explained what to listen)."

Denon AVR-X4700H is better than Arcam AVR20 | Audio Science Review (ASR) Forum

So it sounded like his family members only heard it after he explained "what to listen"..

 

[AcuDefTechGuy]

Interesting enough, someone on ASR just posted this:

"Long time Denon user, (despite the measurements and various advise on this forum) couldn't resist the deal for an openbox Arcam AVR20 for £2240 (new retails for £3199). First thing I noticed is 'transformer hum', may be not audible for average user but I certainly did (and family members once I explained what to listen)."

Denon AVR-X4700H is better than Arcam AVR20 | Audio Science Review (ASR) Forum

So it sounded like his family members only heard it after he explained "what to listen"..

Ignorance is bliss.

Now they can't unhear it.

 

[ejsmoove]

I did not really expect to notice any sonic difference, I wanted to give Class D a try

I was considering switching with the following reasons:

• Lose some weight on my amps (partially solved, still pretty heavy)
• Get rid of the slight "Hiss/Power Buzz" that was coming from my tweeters (Check)
• More power efficient amp (Check)
• If it was sonically a wash, sell my A31/A51 consolidate to 2 amps instead of 3 and pocket a little $$ for other things (In Process)

I was completely happy with the sound quality from my Halos and I am happy to report, I don't feel like I lost anything switching over to the class D ATI. Will live with it for a few weeks and if all goes well, will change over completely. I am also going to give my untested opinion: I felt there were some sonic differences, but I am not going to even touch the subject, because I have done no testing to back that statement up. Going to play around with it over the weekend.

Parasound Halo A31

• Halo wins the beauty contest hands down, its also packaged nicer with a double box
• I like the fact that Halo has a 12v Trigger input and output + threshold knob
• Manual Gain control and THX Ultra2 certification (Not a big deal)
• Amp Transformer hum can only be heard if I put my ear next to the unit
• Sound Quality is excellent, no complaints
• Had slight tweeter noise that can only be heard 2-3 feet away from speaker, but the anal retentive person that I am, wanted to get rid of it.

ATI AT524NC

• The ATI is not the prettiest amp, but this will go into my equipment room
• It is DEAD SILENT - I do not hear transformer hum, and the slight Tweeter noise I noticed on my A31 is gone (This was a huge selling point for me)
• Only 1 12v Trigger Input, not a huge deal as my Pre/Pro has 2 outputs and I plan on running 2 amps
• It is about 25-30lbs lighter then the 80lb Halo, which is nice but still heavy
• As far as moving it, even though the weight is more than other class Ds, it's smaller form factor (not as deep) makes it a lot easer to take in and out vs the longer Halo because of the more centralized weight distribution
• I like the speaker binding posts better on this vs the Halo
• Save significant $$$ vs the comparable Halo

Bottom line for me was that class D impressed, not going to complain about a 7 year warranty either.

Weird. I've had my A31 a month and its dead silent with my ear nearly touching the unit. No tweeter noise and no transformer hum but I also don't have any tweeters with the Martin Logan 11As.

 

[Cos]

Nothing wrong with the Parasound Amps, sonically they worked as expected. Weight loss and less heat were the two biggest changes,.

 

[surajg]

I said some may be more sensitive to hearing the hum because I wanted to be diplomatic about it, instead of saying things like: you didn't listen careful enough, close enough, room's not quiet enough, you are exaggerating, or worse, you must be deaf. RichB called me out on that so okay now I am being blunt.., sorry!

Yes, "electrical environmental issues" including those related to the incoming power that you can't do much about it unless it is serious/obvious, or caused by your other devices in the house, are likely the culprit, more often than not.

To your last question, even under the best scenario, that is, the power source is super clean, transformers will still hum but the good ones fed with clean power source will only hum loud enough to be audible with you ears touching the chassis nearest to the transformer. And, all else being equal, larger transformers hum louder.

I posted some links earlier so one can dig into why they hum. Without digging into the details, it should be easy to understand if something vibrates, there will be noise. Obviously transformer core laminate sheets and windings must vibrate with the AC so it will make noise, but the noise could be kept to the point you may consider it "silent".

If you look at Denon's marketing hype about their sand type Aluminum casting filled with resin approach in "eliminating" vibration. That made sense to me and it is believable that such expensive transformers should be near silent, my only issue is with the word "eliminate". If they chose to be more honest, they would have substituted it with "substantially reduce..", or even "minimize", but then I would be splitting hair.

May be its time to agree that if one cannot hear the hum regardless, or can hear it only with the ears touching and with the room under near silent condition, then the transformer is "silent". I am totally fine with that, and I am sure you are as well.

Since your amps are all hum free, and knowing you have much more than 1 or 2 amps, you obviously have clean power coming into your electrical panel, lucky you!

I appreciate your candidness and your efforts to navigate the discussion diplomatically. It's essential to address these matters with sensitivity, and I understand the intention behind your previous approach.

Regarding electrical environmental issues and the hum you mentioned, it's indeed a common challenge, often stemming from factors beyond our immediate control, such as incoming power quality or other devices within the household.

Your explanation about transformer hum and its correlation with the power source clarity makes perfect sense. Even in optimal conditions, transformers may emit a hum, albeit at levels only perceptible when in close proximity. And you're correct in pointing out that larger transformers tend to produce louder hums.

The links you provided earlier offer valuable insights into the technical aspects of transformer hum, highlighting the correlation between vibration and noise generation. Denon's approach to minimizing vibration through specialized casting techniques seems logical, though perhaps their use of the term "eliminate" could be interpreted more accurately as "substantially reduce."

Ultimately, if the hum is imperceptible except under extremely quiet conditions or when in direct contact with the transformer, it's fair to consider it "silent." It's a pragmatic approach that acknowledges practicality while ensuring accurate characterization.

Indeed, the absence of hum in your amplifiers suggests a fortunate circumstance with clean power delivery to your electrical panel. It's a situation many would envy!

Thank you for your insights and contributions to the discussion. Your knowledge and willingness to engage enrich our collective understanding of these technical nuances.

 

[highfigh]

The biggest issue it solved for me was the tweeter noise (even though is was only audible within 2 ft of the speakers), that along with not impacting sound quality would have been enough. The main reason I decided on ATI, was the warranty. It is 4-5 years longer than any of the competition.

Side note, I called ATI for support for a question about the cord. Its has a 20A power connector on the amp with15A wall plug. Someone actually picked up, took the time to answer that question and a few others, so A+ on support for me so far.

Did you have the input level control turned wide open? That's not reference level and it's a good way to have noise.

The Parasound warranty for Halo models other than CD-1 and D3 players is 5 years as long as they were purchased from an authorized dealer.

 

[Cos]

Did you have the input level control turned wide open? That's not reference level and it's a good way to have noise.

The Parasound warranty for Halo models other than CD-1 and D3 players is 5 years as long as they were purchased from an authorized dealer.

I was referring to other Class D Amps, most other brands do not offer that long a warranty. As for the Parasound I did tweek the level control nob, it did not effect noise. Granted the noise could not be heard from 3ft away or more.

 

[AcuDefTechGuy]

I was referring to other Class D Amps, most other brands do not offer that long a warranty.

Yeah. It says a lot to me when a company can offer a 7 YR warranty on all their amps (not just their flagship amps) while some smaller companies can offer only offer 1 YR warranty or 2 YR.

 

[highfigh]

I was referring to other Class D Amps, most other brands do not offer that long a warranty. As for the Parasound I did tweek the level control nob, it did not effect noise. Granted the noise could not be heard from 3ft away or more.

So, you reduced the input control to minimum and the noise remained?

While the usual warranty covers a certain length of time because "They either go immediately, or last forever", it would seem that the manufacturers of ClassD amplifiers aren't so confident in the 'last forever' idea. Bryston has offered a 20 year warranty for a long time but they aren't Class D.