replacing an old high end receiver

[rec head]

I was just thinking that the PC that does all my A/V is the oldest piece of equipment I have in use. Then I remembered that my Denon 3808 is still in use as a power amp only.

I just switched to separates. I now have a Dirac enabled pre/pro and a class D amp for the L/C/R speakers. I am hearing things in songs that I never heard before. Loving it.

[sailor]

Count me on the room correction train. I replaced a B&K AVR202 (~$3k new) with a Denon x3700 last fall (~$1k) and everything is much cleaner especially in the bass/sub region. Sound is not quite as warm but I could probably dial that back in. I wish receivers were on class D already, the new stuff has >100db signal to noise+distortion and runs cool with low power usage. Modern technology is actually better when it is designed to be.

[sine]

Sound is not quite as warm but I could probably dial that back in. I wish receivers were on class D already,

Several Pioneer Elite AV receivers have Class D amplification. Some Onkyo receivers do as well.

[pomole]

Im glad to see the renwewed interest in proper audio gear. I no longer pretend to be an audiophile but still like gear that plays music correctly. There so much good stuff out now, and the internet makes used/vintage gear very accessible.

I recently went back to receivers and got a new Cambridge Audio AX85. This is a humble choice but i wanted simplicity: good sound characteristics and enough power to do what i need in my small home. The phono section is very good for the price and it even takes streaming. Most of all- the tuner section works well and i can listen to all the programs clearly. Check it out if your in the market for a new receiver or basic integrated.

[davids]

I've only heard one Class D amp (Rogue's integrated) and was not a fan. I thought it sounded both dark and kind of sharp. YMMV

[rec head]

My new amp is NCore 502 modules. This guy is building them for a steal. https://www.audiosciencereview.com/f...ncement.16835/ He does not have a real business or even website yet but I'm really happy with it. In that post there is a link to a review on the same website. These reviewers are not known for just handing out praise. I looked into building the amp myself but couldn't do it for what it cost to get it from Buckeye Amps.

[davids]

I'm not a fan of that website, Audio Science Review. Their position is that measurements correlate directly with sound quality. That has not been my experience.

This is not a diss of the NCore 502. I haven't had the opportunity to hear it!

[9tubes]

Class D is becoming more popular due to the cost advantage. I have a NAD 758v3 which is Class AB and it appears there are still plenty of AB designs around (even MacIntosh is using AB these days). But here's the thing: I wonder if I could really hear the difference. My suspicion is that sound processing makes far more difference than class of amp, if the amps are suitably matched in quality level.

[9tubes]

I'm not a fan of that website, Audio Science Review. Their position is that measurements correlate directly with sound quality. That has not been my experience.

This is not a diss of the NCore 502. I haven't had the opportunity to hear it!

I have similar suspicions about Audio Science Review. Maybe I'm biased because I have a NAD 758v3 and they got very poor measurements. The sample test results were far from what would be objectively expected. I was taught that the first rule of engineering testing is that if you get test figures that are wildly anomalous from expected, the first thing to do is check the test equipment, then the test protocol, then get another sample. The website has refused to do any of the above. However, they have received 783 comments and 102,000 page views, so refusing to retest has had its benefits.

[spopepro]

Apologies up front for sending this so far OT

I'm surprised to see so many here are cool with class D... promoting minuscule THD numbers and S/N ratios is like telling someone your bike is good because of the modulus of the CF fiber in the tubes.

It's not that I think switching amplifiers can't be made to sound good, I just think making them sound good requires a ton of parts, and the more stages and parts, the more issues imho. There's two reasons I think class d is now being pushed in the high end world: 1. most folks are buying on buzz, reputation, and numbers and damn if you can't make the numbers (WPC, THD, S/N, etc..) pop with class d. and 2. the supply lines are drying up for good linear components so folks are being forced into switching mosfets. And it's true--all the money is in getting transistors that behave close to perfectly as switches and nothing is going to bring back Hitachi, Toshiba, or Semi-South discrete linear silicon. Pass has been able to pull an e-richie and get linear systems to keep some of the supply chain going in good jfets, but like good steel tubing and lugs, eventually the supply chain will dry up because the industry has gone another direction. I'm sure consumer expectations will adjust whether it's actually and improvement or not (and my money is on not).

All that said, having listened to some of Linkwitz's personal speakers I know DSP and intentional correction for the realities of imperfect parts and rooms can have really, really good results. I also *enjoyed* Pass' cheapo open baffle setup with a first-watt amp in the same room better, although it was not an A/B test in any manner (Siegfried was demonstrating speakers, Nelson was demonstrating an amp, and it was a DIY event in an awful space for listening). There's a lot to be said for a simple system that fits well together. It's the gestalt of it yo. It's why I suspect davids' system works so well--a simple mu-follower voltage stage into a complementary BJT circuit operating fully in class A, feeding an electronically simple multi-way speaker that is forgiving about directivity (at least horizontally, just don't stand up...) should be enjoyable. Personally, I've found satisfaction in going as simple and as few parts as possible source to speaker.

[Mark Kelly]

I've only heard one Class D amp (Rogue's integrated) and was not a fan. I thought it sounded both dark and kind of sharp. YMMV

You are possibly very sensitive to IMD (intermodulation distortion).

[sine]

I'm surprised to see so many here are cool with class D...

My first AV receiver was a Yamaha DSP-A1 which powered Sonus Faber speakers. Bit of a gamble as the receiver was purchased at one store and the speakers at another....never auditioned together. Once installed I found the sound uninspired and a bit harsh but I stuck with it for many years. The speakers are exceptional (auditioned at audio store in Bethesda, MD) and craftsmanship.....unmatched Italian.

The Pioneer Elite SC-05 that I purchased in '08 was based on print reviews only......aka another gamble. That the price was recession induced 50% off....helped. I hooked up the Elite and I was impressed. The sound was smooth.....and unlocked much of the speakers potential.

Sold the Yamaha for decent money (the unit has it's fans) and the Elite is very much enjoyed to this day.

Can't comment on today's higher end products. Have not auditioned anything in the last 10+years.

[davids]

You are possibly very sensitive to IMD (intermodulation distortion).

I've been cursed with the gift of golden ears...

Like I said, I've heard one and only one Class D amp, the Rogue Sphinx. And it's made by a company whose products I clearly admire, since I own a Rogue pre-amp. So I really can't generalize to all Class D amps. But I'll admit my experience kept them off my shopping list for an amp.

And also like I said, the Schiit Aegir is a seriously great amp. As long as you don't need much power. I was worried that it wouldn't be adequate for my moderately inefficient speakers in a medium-sized room at reasonable old-guy volume. But it is way more than adequate for me!

now.jpg

[rec head]

I only brought up the ASR site because that is where Buckeye Amps is running his business from. He is just a grad student building amps in his spare time. As for the site I think of it as a tool. I don't base my purchases on their reviews but do use like to see what they said.

As for the Class D debate. I get plenty of clean power and don't know what IMD is. I'd like to be able to hear better but sometimes a curse can be a blessing.

[spopepro]

Intermodular distortion, which is the second most common distortion after harmonic inherent to all amplifiers. IMHO it’s the more important one, since even numbered harmonics are mostly consonant (and even the 3rd harmonic is a perfect interval) I don’t think harmonic distortion is something most people “hear” and indeed some folks report liking it, feeling like it adds to the “depth” or “richness” of the sound. A good example of this in live performance is really good chamber music. If you listen to a great brass quintet who is playing exceptionally well in tune additive interference can make some of the harmonics sort of pop into the sound and it’s kind of magical.

IM is harder to track down, and you’ll need someone like Mark who is a real engineer rather than me to go into all the reasons why. But my understanding is that it’s due to the non-linear interplay of different components and different signals. So it doesn’t get measured or reported as often as harmonic distortion because it’s harder to measure. I think the only time I feel like I can “hear” IM clearly is on cymbal crashes. They sound excessively “crunchy”.

Switching amplifiers generate gobs and gobs of noise from the switching. They then are supposed to filter all of it out with a large set of low pass filters (the mess of inductors and caps on those modules). They also naturally generate quite a bit of harmonic distortion, but because gain is cheap, they use gobs and gobs of negative feedback. They remind me a lot of op amps—the numbers are great, but no one is going to mistake the TL072 as a great sounding amplifier.

I’m not opposed to measurement, it’s an important part of the process. I just think that we don’t always measure or emphasize the right things. It’s like folks who measure the TDS in their espresso and declare that the bigger numbers are better, when taste rarely backs it up. But there’s a class of folks who will say “well, it’s objective, so people’s taste is not to be trusted” instead of questioning the meaning of the measurement. After all, it’s about the enjoyment of taste, or sound. As Pass says “it’s entertainment, not dialysis.”

My amp makes around 3 watts per channel at about 4% harmonic distortion depending on configuration. It sounds great.

[Bob Ross]

I don’t think harmonic distortion is something most people “hear” and indeed some folks report liking it, feeling like it adds to the “depth” or “richness” of the sound.

Heh-heh. When I was in college circa 1979-80 my roommate had a wonderful sounding hi-fi consisting of a pair of McIntosh MC-30 monoblock tube amps with a Dynaco preamp and Acoustic Research AR4 speakers. After extolling the virtues of those MC-30 amps to a friend of his who was an electrical engineer at MIT, his friend offered to benchtest the amps.

They consistently measured between 8% and 10% harmonic distortion.

But as I said... wonderful sounding.

[9tubes]

Heh-heh. When I was in college circa 1979-80 my roommate had a wonderful sounding hi-fi consisting of a pair of McIntosh MC-30 monoblock tube amps with a Dynaco preamp and Acoustic Research AR4 speakers. After extolling the virtues of those MC-30 amps to a friend of his who was an electrical engineer at MIT, his friend offered to benchtest the amps.

They consistently measured between 8% and 10% harmonic distortion.

But as I said... wonderful sounding.

Your friend had far more disposable cash at university than I did. : )

[davids]

I’m not opposed to measurement, it’s an important part of the process. I just think that we don’t always measure or emphasize the right things. It’s like folks who measure the TDS in their espresso and declare that the bigger numbers are better, when taste rarely backs it up. But there’s a class of folks who will say “well, it’s objective, so people’s taste is not to be trusted” instead of questioning the meaning of the measurement.

This.

I was in the measurement camp until I had the opportunity to hear two systems, the only difference between them being the turntable and tonearm - the rest was not just the same brand & model, but the actual items: cartridge, preamp, amp and speakers. Changing between the two well-regarded turntables made a large difference in the sound quality of the music.

When I got over my shock, I realized (even at the tender age of 24) that whatever the experts were measuring was not capturing all of the important qualities of the equipment.

I started trusting my ears. I listen to the characteristics of live music - tonality and dynamics are particularly important to me - and the characteristics of recorded music. I've tried to create systems that reproduce the characteristics most important to me.

[Mark Kelly]

Switching amplifiers generate gobs and gobs of noise from the switching. They then are supposed to filter all of it out with a large set of low pass filters (the mess of inductors and caps on those modules). They also naturally generate quite a bit of harmonic distortion, but because gain is cheap, they use gobs and gobs of negative feedback. They remind me a lot of op amps—the numbers are great, but no one is going to mistake the TL072 as a great sounding amplifier.

FWIW the feedback in a class D amp is applied before the output filter* and is there to correct the non-linearity in open loop gain rather than the noise.

I mention this not to nit pick but because it is also the cause of the IMD: since the open loop gain is non linear, the feedback is also non-linear but in the opposite sense. Applying feedback cleans up the THD but inevitably causes IMD: two inputs into a non-linear stage is the way you build a modulator if you want one (eg for a FM radio).

The non-linearity in the open loop gain is because the output transistors are not perfect switches; such a thing does not exist. I believe current research is all about improving the switches, including in some cases a move away from silicon to new semiconductors such as gallium nitiride. The idea is to get the open loop gain near enough to linearity to be able to reduce the feedback and improve the sound quality.

It used to be said that if an audio circuit wasn't linear enough to work without feedback it would measure well but sound bad when the feedback was applied. Maybe the Class D people are remembering this.


* this is largely because the output filter inserts a large phase delay which would make the feedback loop very hard to stabilise

[Bob Ross]

Your friend had far more disposable cash at university than I did. : )

True story: He picked up those two MC-30s -- along with two more MC-30s, a pair of of MC-275s (!), and at least one other monoblock amp of similar vintage -- from an auction for less than $200 total.

They all had to be re-tubed, and a couple of them needed the output transformers replaced. Selling one of the MC-275s as-is more than covered the cost of the repairs; selling the other MC-275 after it was fixed paid for his room and board for an entire semester.