Is 10dB enough?

[Andrej]

I remember a post, I think by Amir, that if the preceding device has at least 10dB SINAD advantage, it will not negatively impact the performance of the device in question. For example, if the DAC has 10dB higher SINAD than the pre-amplifier, which in turn has a 10dB higher SINAD than the power amplifier which has a 10dB higher SINAD than the loudspeaker, the determining factor, in terms of fidelity/SINAD, is the loudspeaker. Of course, speakers have many other criteria for evaluating their performance. The question is, if the 10dB rule is applied to the signal chain, can one rest easy until the loudspeaker distortions are sufficiently reduced. How does one measure the most relevant metric (at the speaker level) to apply in this scenario? THD? IMD?...

Following this thinking, and building speakers myself, I have concluded that Hypex plate amps provide all the fidelity I will need for a long time to come, even if my current speakers opperate at less than 0.1% THD from 160-10kHz at a reasonably loud listening level (>90dB @ 1m). Am I wrong? How can I meaningfully improve on the Hypex plate amps? Thanks!

 

[Blumlein 88]

I don't know if that is really what Amir said in regards to SINAD. This is a case of over-simplifying something. Adding distortion linearly from component to component doesn't work quite that way plus SINAD is distortion plus noise. For your purposes you need to look at noise separately from distortion.

You might read that measuring something you need the measuring device to have distortion or noise 15 db (preferably 20 db) lower not to make a meaningful difference in what is being measured. Has to do with db being a log scale so simple addition/subtraction doesn't work to give the result.

We could expand on why this is so if you wish. Bottom line for your purposes is the Hypex is low enough in distortion that it won't impact what comes out of your speakers unless you push the amp very much to or a bit beyond its limits.

 

[fpitas]

Following this thinking, and building speakers myself, I have concluded that Hypex plate amps provide all the fidelity I will need for a long time to come, even if my current speakers opperate at less than 0.1% THD from 160-10kHz at a reasonably loud listening level (>90dB @ 1m). Am I wrong? How can I meaningfully improve on the Hypex plate amps? Thanks!

I think you're right. They have far less than 0.1% THD or IM, in fact they're far better than almost any speaker.

 

[DVDdoug]

Following this thinking, and building speakers myself, I have concluded that Hypex plate amps provide all the fidelity I will need for a long time to come,

Most amplifiers are better than human hearing unless over-driven into clipping. But sometimes noise can be an issue depending on the sensitivity of your speakers and how close you are to your speakers (and ambient room noise).

If you aren't hearing noise (hum hiss or whine in the background) and you're not hearing distortion when you crank it up, you're good!

 

[DonH56]

As has been said, most amplifiers have much lower distortion than speakers by a wide margin. You need enough power to reach your listening levels without clipping, assuming the speakers can handle that much power, and low enough noise to not be bothersome. The -10 dB rule of thumb is to contribute <10% additional whatever (noise, distortion) but in a chain of components that can be misleading because the gain of each component also matters. If a component has 10 dB lower noise, for instance, but also 10 dB lower gain so you need to turn up the volume, then you've gained nothing.

SINAD itself is a nice one-number answer but can hide a lot of things. Generally if SINAD is well below audibility then it's a don't care to me. However, if it is relatively poor, then you need to dig deeper to see why. Bad SINAD could be a high noise floor, high distortion, high power supply spikes, etc. and they affect the sound differently. If the distortion is high, then the frequency distribution matters. High 2nd or 3rd harmonics tend to be less annoying than higher-order terms like 5th, 7th, 9th, etc. If noise is high (SNR is low) but you sit fairly far from fairly insensitive speakers, then noise may not be an issue, as compared to sitting closer to a set of highly-sensitive horn speakers. And so forth. It gets complicated.

That said, IME/IMO, as long as the Hypex or any other amps have low enough noise and high enough power to meet your needs then you'll be fine.

 

[Andrej]

Thanks all, I think we are all in agreement with some caveats about gain in various components. Since Hypex plate amps can take digital input, gain should not be so much of an issue. It is more likely to be a problem if using it with an AVR for HT, so I'll pay more attention in that case. With active speakers sensitivity is harder to pin down, but the midrange and the tweeter are well above 90dB/1m. There is barely any sound with my ear by the mouth of the horns, so I do not see noise as a problem. You can see some measurements of the future center channel speaker in https://www.audiosciencereview.com/...bargain-drive-units.45505/page-3#post-1703416 where the distortion varies from about 0.2-0.4% at 106 or so dB @1m. I have bigger midrange waveguides using an 8" driver with comparable (slightly better at the lower end, 170-300Hz) THD. Still looking for the best 15" pro driver for the bottom end. I welcome any suggestions! I am not concerned with lowest frequencies as I am planning to add multiple subwoofers in the future. Everything is modular so that I can mix-and-match various pieces, as you can see in the attached images. Work in progress

 

[sam_adams]

Ack-shew-ally, 6dB is all that is needed—approximately 1 digital bit for each downstream device—to preserve the original fidelity of any DAC or other source. Brief mention is alluded to in this article from Benchmark. So, 10 dB is definitely enough.