High end Vintage SS amp vs the best Class D amps

[Plcamp]

the RF issues are an added complication.

Maybe not entirely added (rf issues can exist in any product), but certainly more complex.

I am wondering…while it is obvious that amp designers/manufacturers pay attention to suppressing rf noise from affecting their products, is there any rf immunity standard that is the design goal? Is rf immunity quantified as a product release requirement?

 

[Goodman]

If your question is "classic" amplification vs "modern" class D, I have one anecdotal experience with one of my customers who measured FR and distortion from his speakers powered by my stereo Purifi on one side, good old class A monoblocs on the other side.
Amplifiers of equivalent power, level matched at 1 kHz, very well designed listening room.
Basically, the FR and distortion were almost the same above 150 Hz. But my amp was allowing 1.5 dB more on the whole spectrum below 150 Hz. So completely different sound balance at the end.

The beginning of your statement is true, even if a bit of attention is needed when integrating these modules and complying to various regulations requires a lot of work. The end is completely false. Getting a high performance class D requires a lot more engineering than a high performance class H. This is why only 3 to 4 companies are on the market supplying both minor and major OEMs.

Of course, you are right, I was exagerating to make a point, but why all this efffort to promote class D? I still think it would be useful, even if more complicated to revisit class H and G.

 

[tomtoo]

Of course, you are right, I was exagerating to make a point, but why all this efffort to promote class D? I still think it would be useful, even if more complicated to revisit class H and G.

Couse class d is in many use cases superior.
This has nothing to do with promotion.

To provokative, why should we hang on old, expensive, inefficent amp topologys, when they not sound better???

 

[MaxBuck]

I’m going to jump in with a completely passive but important reason for loving the new class-D amps. I was sceptical that class d could perform in real world conditions. Light and inexpensive seems to be counter intuitive. An amp that has 6 channels rated at 4ohm @500 WPC. That’s 3K on tap. In a unit that is the size of a Blu-ray player and maybe lighter in weight. I said “No-Way”. Then Amir did some measurements and a tear down review. All this power for under $1.6K? But in the end, in actual use case operation, all of the above faded away to background noise rationale.

You see I live in South Florida. The land of high heat and humidity. Where the home is locked up tight running A/C 9 to 10 months out of the year. Where the Electric bill runs second only to your Mortgage payment. It’s the Heat, or rather the lack of any! Pushing low Ohms load speakers this little 6ch Amp barely gets warm. My previous Amps were like room heaters pumping out gobs of heat. That I then had to run the A/C temp thermostat even lower to compensate. This major benefit was unexpected but most welcome. My cooling costs have dropped more than 30% this year alone. Essentially paying for the Amp in its first year of use. For comparison last year I averaged 10 run hours a day on the A/C. This year I am seeing 6 to 7 hours a day. The outside temperature has been essentially the same over the time period. 30% reduction in run time on my A/c System is another form of savings not calculated.

Use case FYI. I run my gear hard. My System is on for about 12-14 hours a day. Every day. I am retired and have some mobility restrictions. My use case is pretty extreme but I think it’s worth consideration. The cost savings are derived from the increased efficiency of the amps themselves and the reduced heat output as it relates to cooling needs of the home. I came to the class D amps for the improvements in the normal power amp specs. However, I will keep this amp and replace all the rest of my amps with class D for the Heat factor. Hard to beat purchases that pay for themselves.

Great points. I'm neither as intensive in use nor as activity-limited, but live in a very hot climate. As you say, the electrical savings for you and me go way beyond the draw from the amplifier.

 

[Goodman]

I would say a Class D from scratch would be incredibly challenging. Beyond my abilities for sure. A class D from a bulletproof module- not hard at all. Hypex and Purifi are handing the crown jewels to the assemblers. All they have to do is not f#%k it up. Some do, some don't.

Super high performance Class AB is an art and it sadly appears much of the gurus have retired or died, and it's almost like it's being re-discovered/re-invented again. Look at the AHB-2 Benchmark. It uses 1980s technology, wrapped up in a few (?) patents and hand waving. But it works..

The Benchmark is actualy on top of my list to test (listen=

I would say a Class D from scratch would be incredibly challenging. Beyond my abilities for sure. A class D from a bulletproof module- not hard at all. Hypex and Purifi are handing the crown jewels to the assemblers. All they have to do is not f#%k it up. Some do, some don't.

Super high performance Class AB is an art and it sadly appears much of the gurus have retired or died, and it's almost like it's being re-discovered/re-invented again. Look at the AHB-2 Benchmark. It uses 1980s technology, wrapped up in a few (?) patents and hand waving. But it works..

The Benchmark AHB-2 is actualy on top of my wishlist to try, however it is not a powerful amp so you probably need 2 at €3650 each! Some of the old Gurus are still alive and kicking, Bob Carver please come in!

 

[boXem]

Of course, you are right, I was exagerating to make a point, but why all this efffort to promote class D? I still think it would be useful, even if more complicated to revisit class H and G.

It's a good question. Two things come in my mind, there may be a lot others:
- even if good to very good, class H or G are less energy efficient that class D. Like it or not, founding R&D for something highly energy efficient is easier.
- class H and G necessitate complex power supplies while class D is working with whatever off the shelf. Increased procurement costs + integration complexity

 

[Goodman]

Great points. I'm neither as intensive in use nor as activity-limited, but live in a very hot climate. As you say, the electrical savings for you and me go way beyond the draw from the amplifier.

I share your concern for wasting energy, I have a pure class a amp 20W I use only in winter months, it is overrated anyway.

 

[Koeitje]

I would say a Class D from scratch would be incredibly challenging. Beyond my abilities for sure. A class D from a bulletproof module- not hard at all. Hypex and Purifi are handing the crown jewels to the assemblers. All they have to do is not f#%k it up. Some do, some don't.

Super high performance Class AB is an art and it sadly appears much of the gurus have retired or died, and it's almost like it's being re-discovered/re-invented again. Look at the AHB-2 Benchmark. It uses 1980s technology, wrapped up in a few (?) patents and hand waving. But it works..

I think I should have worded it differently. Shouldn't have said implementation, but design. Like you said, its incredibly hard to make a high performance class D amplifier.

I also agree on others not pushing class AB at all. Class A is dead for me regardless.

Class D from modules is harder class A/B from scratch? I guess I'll just call into work today and tell them to have the cleaning lady do the class A/B designs, and I'll go fishing.

I never said a module was hard, I said designing your own switching amplifier implementation is hard. But my wording might have confused you, should have said class D design. It is harder to design a good class D design than a class A/B amplifier.

 

[DWPress]

Like @AdamG247 I've moved to good class D amps for heat reasons as well and I live in N MI where winter is a thing for a good 7 months but I sit about 2 feet away from the gear.

I was using a stack of 3 NAD 2200s in BTL which Amir measured here on ASR and were found to be quite good for 1980's tech coming in with a SINAD of 95 just below a modern Nord NC500. Now I never ran the NADs on my speakers since I changed drivers and rebuilt them so can't comment on differences but I suspect there wouldn't be anything audible and not much measurable but my left leg stays a lot cooler!

 

[Mart68]

A couple of years ago I compared a TPA3116 against a Mk 2 Krell KSA100. Here's a pic of that happening although it's not very good one



The Krell won but it does have about 15 times the power.

 

[tomtoo]

I think I should have worded it differently. Shouldn't have said implementation, but design. Like you said, its incredibly hard to make a high performance class D amplifier.

I also agree on others not pushing class AB at all. Class A is dead for me regardless.


I never said a module was hard, I said designing your own switching amplifier implementation is hard. But my wording might have confused you, should have said class D design. It is harder to design a good class D design than a class A/B amplifier.

" ....It is harder to design a good class D design than a class A/B amplifier...."

Why do you think so?

 

[somebodyelse]

I am wondering…while it is obvious that amp designers/manufacturers pay attention to suppressing rf noise from affecting their products, is there any rf immunity standard that is the design goal? Is rf immunity quantified as a product release requirement?

Both the rules and the likelihood of enforcement vary depending on where you are. In Europe you're meant to meet the requirements of the EMC Directive 2014 (among other requirements) in order to use the CE mark and sell in Europe. That includes limits for both conducted and radiated emissions. The FCC in the US has similar standards with stricter requirements on the paperwork. How actively they're policed is another matter entirely, and there are apparently ways to pass the letter of the requirements while failing the spirit.

 

[boXem]

" ....It is harder to design a good class D design than a class A/B amplifier...."

Why do you think so?

Because the requested level in control theory and mathematics is higher.

 

[jae]

The biggest criticism of Benchmark's $3000 class AB is the lack of power, and the answer to that is a Purifi class D stereo build at half the price (+/-) for the cheapest option and almost double the power at similarly low distortion. This is going to be the best option for probably 99%+ of people when looking at the purchase holistically. If for whatever reason you need more than ~400+ WPC then you can opt to give up some specs for Hypex NC1200 or NC2k with not much change in price, maybe a couple hundred more. When you are comparing these to class A amplifiers that have comparable specs, or cost many thousands or tens of thousands and may in fact have inferior specs at worse, the answer is fairly clear if you care minimally about aesthetics or ease of future serviceability. If a module dies outside of warranty you can just replace it easily or even upgrade it with whatever is the best in the future. I feel like with these options available most big class A amps are for the ostentatious, or those in need of a space heater in winter.

 

[AdamG]

General FYI. I just talked myself into buying another 6ch Nc502mp amp from Buckeye Amps for $1600usd shipped. Have already made arrangements with Amir to bench test then do a Tear down inspection as well. Amp is projected to ship directly to Amir around Mid-September. Will be the first Hypex Nc502mp tested by Amir.

 

[Doodski]

General FYI. I just talked myself into buying another 6ch Nc502mp amp from Buckeye Amps for $1600usd shipped. Have already made arrangements with Amir to bench test then do a Tear down inspection as well. Amp is projected to ship directly to Amir around Mid-September. Will be the first Hypex Nc502mp tested by Amir.

If all things are in moderation and you are buying a 6 channel Nc502mp amp setup then what is going overboard? Love it. 6 channels of lotsa powaH! At that kind of power output and current draw I imagine this thing is going to need one of those 20 amp breakers in the breaker panel.

 

[AudioSceptic]

I’m going to jump in with a completely passive but important reason for loving the new class-D amps. I was sceptical that class d could perform in real world conditions. Light and inexpensive seems to be counter intuitive. An amp that has 6 channels rated at 4ohm @500 WPC. That’s 3K on tap. In a unit that is the size of a Blu-ray player and maybe lighter in weight. I said “No-Way”. Then Amir did some measurements and a tear down review. All this power for under $1.6K? But in the end, in actual use case operation, all of the above faded away to background noise rationale.

You see I live in South Florida. The land of high heat and humidity. Where the home is locked up tight running A/C 9 to 10 months out of the year. Where the Electric bill runs second only to your Mortgage payment. It’s the Heat, or rather the lack of any! Pushing low Ohms load speakers this little 6ch Amp barely gets warm. My previous Amps were like room heaters pumping out gobs of heat. That I then had to run the A/C temp thermostat even lower to compensate. This major benefit was unexpected but most welcome. My cooling costs have dropped more than 30% this year alone. Essentially paying for the Amp in its first year of use. For comparison last year I averaged 10 run hours a day on the A/C. This year I am seeing 6 to 7 hours a day. The outside temperature has been essentially the same over the time period. 30% reduction in run time on my A/c System is another form of savings not calculated.

Use case FYI. I run my gear hard. My System is on for about 12-14 hours a day. Every day. I am retired and have some mobility restrictions. My use case is pretty extreme but I think it’s worth consideration. The cost savings are derived from the increased efficiency of the amps themselves and the reduced heat output as it relates to cooling needs of the home. I came to the class D amps for the improvements in the normal power amp specs. However, I will keep this amp and replace all the rest of my amps with class D for the Heat factor. Hard to beat purchases that pay for themselves.

"That I then had to run the A/C temp thermostat even lower to compensate."
That's a great plus, but I'm puzzled about one thing. Why would you need to change the thermostat setting? Surely you want the same temp as before? Or am I misunderstanding how your stat works?

 

[AdamG]

"That I then had to run the A/C temp thermostat even lower to compensate."
That's a great plus, but I'm puzzled about one thing. Why would you need to change the thermostat setting? Surely you want the same temp as before? Or am I misunderstanding how your stat works?

I have multiple zone thermostats. The room with all the A/V gear has its own wireless thermostat.

 

[MaxRockbin]

https://www.stereophile.com/content/boulder-amplifiers-2150-monoblock-power-amplifier-measurements

I would say one of the best high power amplifiers ever built.

I'm sure it sounds wonderful until the AC kicks on. You would basically have two space heaters running full throttle in your listening room.

 

[AdamG]

If all things are in moderation and you are buying a 6 channel Nc502mp amp setup then what is going overboard? Love it. 6 channels of lotsa powaH! At that kind of power output and current draw I imagine this thing is going to need one of those 20 amp breakers in the breaker panel.

An older Emotiva XPA-5 will be sold off. I already have one of these Nc502mp 6ch amps running on 15 amp circuit and not a problem yet. I run a 9.2.6 setup. So the plan is to run the base 9 channels on the 502 plus my front heights (slim towers) for a total of 11 channels used. 1 channels sits unused on the front L,R,C,LS,RS. The remaining 4 height channels will be driven by a Denon 8500h. Confused yet? I might be….