My experience with Class-D Amplifiers (Part 1 & 2)

venkatcr

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Thank you for clarifying that. Seems a good option to consider for driving recently acquired Pioneer SP-FS52 floorstanders (6 ohm speaker; max input power 130 watts).
Just be careful about speaker sensitivity. The Lepai has enough juice to blow away high sensitivity speakers. As I mentioned in the article, the Lepai has been measured to deliver 130 watts into 4 ohms. Six omhs, I reckon should get between 90 to 100 wats. All these Class D amps, beyond a certain volume, generate a lot of noise.
 

PCA

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Just be careful about speaker sensitivity. The Lepai has enough juice to blow away high sensitivity speakers. As I mentioned in the article, the Lepai has been measured to deliver 130 watts into 4 ohms. Six omhs, I reckon should get between 90 to 100 wats. All these Class D amps, beyond a certain volume, generate a lot of noise.

Not a super sensitive speaker. Specified sensitivity is only 87dB. Still risky, you think?
 

sud98

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How do Class D amplifiers work for subwoofers? I know there are some manufacturers who build it using AB and some using D. Also, how does Lepai compare to a Crown or a Behringer or even our own Sonodyne or Ahuja?
 

Kannan

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Class D amps have come a long way. I was running a full 4-way active setup in my car with four ALLO 3116D2 boards Diyed into an enclosure.
I had made some jugaad ti run them off laptop adapters.
They sounded quite good.

Hypex models are supposed to be the best of Class D breeds
 

venkatcr

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Not a super sensitive speaker. Specified sensitivity is only 87dB. Still risky, you think?
Should be fine.

How do Class D amplifiers work for subwoofers? I know there are some manufacturers who build it using AB and some using D. Also, how does Lepai compare to a Crown or a Behringer or even our own Sonodyne or Ahuja?
Almost all subwoofers use Class D amplifiers called plate amplifiers.

Comparing Lepai to a Crown or Behringer is difficult. Crown and Behringer are designed to be used in public places. With that requirement, they have enormous power and the capability to drive multiple speakers. Their SNR may not be good.

Sonodyne and Ahuja, though they are also solid state devices, may not be using modern ICs for amplification circuits. They will, most probably, be going the standard transistor route. That needs large power, and will not be able to deliver high SNR.

Cheers
 

sud98

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Should be fine.

Sonodyne and Ahuja, though they are also solid state devices, may not be using modern ICs for amplification circuits. They will, most probably, be going the standard transistor route. That needs large power, and will not be able to deliver high SNR.

Cheers
I was referring to this amp from Sonodyne which claims a SNR of >104db

Also wanted to check is Lepai overstating the power as the rated output is at 10%THD while typically the THD is <0.1%? So what is the real output?
 
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venkatcr

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Also wanted to check is Lepai overstating the power as the rated output is at 10%THD while typically the THD is <0.1%? So what is the real output?
Please view this video -

Results:

(1) Using included 32V power supply, and measured to 1% TDH @1kHz

57 watts @ 8 ohms
75 watts @ 4 ohms.

(2) Using 33V power supply : 96 watts into 4 ohms
(3) Using 35.4 V : 109 watts into 4 ohms.

Cheers

I was referring to this amp from Sonodyne which claims a SNR of >104db
Could very much be possible. But I was not interested in a 4 channel amp. My requirements were different.
 
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shyamv

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Hi Venkat,

Thanks for your detailed impressions on Lepai. I loved it.

I completely agree that Class D amps have come a long way and are going to the mainstay of audio amplification in the years to come. Audiophiles who equate the price of the amp with the perceived quality might turn up their noses at Class D amps but these have been increasing embraced by manufacturers and buyer alike.

I have used a variety of Hypex, UcD, ICEPower, etc and have always been impressed by most of them. I love the low noise floor, clean power, mostly uncolored sound in comparison to Class A or Class AB. This gives me the flexibility to partner with a variety of speakers and not be overly worried about partner matching.
 

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I have been using XTZ Edge A2-300 from about 3 months now with Paradigm Monitor SE 6000F speakers, and results are amazing.
This barely 8 x 12 x 3 inch Class D amplifier replaced my Marantz PM6006 and I am very happy to do so.

So YEAH... Class D amplifiers are no way limited to cheap stuff now, they range from 10 to 10000 $ and competing very well.


1595948930155.png

1595949002455.png
 

audiofreakss

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i have been impressed by the sound of nad c368 class d amplifier which has an bluos module and mqa dac installed add ons.

paired with jm la micro utopia be speakers.any one has tried this amp
 

shankarcams

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A lovely writeup. I love many of the same numbers and am able to totally understand the time points Venkat refers to.
 

sud98

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One thing I wondered about the price to performance ratio of Class D amps. Is it a factor of who is making them rather than whether its Class D or AB?

For example if a Bryston or even NAD makes Class D I am sure they wont be very cheap versus a smaller company based in Asia.
 

raghupb

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NAD does make Class-D gear and their Masters series can cost quite a bit.
Cheers,
Raghu
 

venkatcr

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There are several issues here:

1. Companies such as NAD, Bryston have a reputation that they have worked hard to maintain. Irrespective of the Class they use, I am sure they will spend a lot in terms of optimizing the product as well as matching each amp to their signature sound. Of course, quality is also there.

2. These companies spend a lot on advertisement, marketing, participating in exhibitions, etc. That costs a lot of money and is amortized to the product cost.

3. Their reputation also means they have to maintain spares and service network and ensure the product is repaired and returned to the user ASAP.

4. Irrespective of how old their product is, I am sure they maintain circuit diagrams and BOM of all their products. For example, just a few days ago I wrote to Hsu Research on a hum that my VTF-2 started giving. Within a few minutes, they write back to me as to what to do exactly. With part number and location in the circuit!

5. Again, irrespective of the Class, these companies do a lot of research into sound and how it is to be delivered. For example, IC manufacturers such as TI, ST and others provide the complete circuit diagram for an amplifier based on their chip. They also provide fully populated boards as prototypes. Companies such as NAD may certainly look at it, but they will never use that circuit. They will find ways of improving in every part of the circuit.

6. These companies have a certain size that they find comfort in terms of selling. So they will never use an external power unit as companies such as Lepai do. They would rather design their own and build it as part of their over product design. A Lepai, on the other hand, would use cost cutting to the max extent possible without losing quality.

All these steps cost money, and when we buy a product, we pay a part of these costs.

Now begs the question. Why would a user spend, say, 1000$ for a reputed brand's Class D amplifier, when they can get the same sound, wattage and specifications for $100? Ego? 'Oh, I will never tarnish my sound system with these here today and gone tomorrow products'? That is human nature when it comes to what we love. We would like to show off what we have, not what we hear!! Even if the show off is to ourselves.

I still remember when I lugged my Hsu VTF2 from the US. When I reached Chennai customs, the customs officer asked me what it was. I told him it was a sub-woofer for my HT. He looks at the name, tuts tuts, and whispers in my ear. 'Next time don't buy such trash. Get a Sony!'. Since I was so ill-informed about sub-woofers, he shooed me out with asking for any duty. Poor me!!

The good part for us at least is that some of the Asian companies are beating the pants down of established names in DACs. Companies such as Topping have improved their product so much in terms of specs and usability that established names have to seriously rethink their strategy. The bad part for us is that these Asian companies, once they attain a certain reputation, have started charging what the established companies would charge for their product. But again comes the question - we would happily pay $2000 for a Benchmark DAC. Would we pay $1500 for Topping DAC that has better specs?

Something we all need to think about. Why should I not have two Lepais with one as a standby spare? At 200, it will still be 1/5th of what I have to pay otherwise.
 

rpanand25

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I want to know how how FX audio D 502( available in HiFi mart) fares for entry level class D amp given that it ticks all the boxes for me so far as inputs are concerned. The amp section appears to have similar claimed specifications ( TAS5342 )as that of ST TDA7498E i.e 2x108W into 4Ω . The implementation will be different I know. This for driving Infinity 89db bookshelf speakers with 6.5 inch mid bass.
 

guddu478

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There are several issues here:

1. Companies such as NAD, Bryston have a reputation that they have worked hard to maintain. Irrespective of the Class they use, I am sure they will spend a lot in terms of optimizing the product as well as matching each amp to their signature sound. Of course, quality is also there.

2. These companies spend a lot on advertisement, marketing, participating in exhibitions, etc. That costs a lot of money and is amortized to the product cost.

3. Their reputation also means they have to maintain spares and service network and ensure the product is repaired and returned to the user ASAP.

4. Irrespective of how old their product is, I am sure they maintain circuit diagrams and BOM of all their products. For example, just a few days ago I wrote to Hsu Research on a hum that my VTF-2 started giving. Within a few minutes, they write back to me as to what to do exactly. With part number and location in the circuit!

5. Again, irrespective of the Class, these companies do a lot of research into sound and how it is to be delivered. For example, IC manufacturers such as TI, ST and others provide the complete circuit diagram for an amplifier based on their chip. They also provide fully populated boards as prototypes. Companies such as NAD may certainly look at it, but they will never use that circuit. They will find ways of improving in every part of the circuit.

6. These companies have a certain size that they find comfort in terms of selling. So they will never use an external power unit as companies such as Lepai do. They would rather design their own and build it as part of their over product design. A Lepai, on the other hand, would use cost cutting to the max extent possible without losing quality.

All these steps cost money, and when we buy a product, we pay a part of these costs.

Now begs the question. Why would a user spend, say, 1000$ for a reputed brand's Class D amplifier, when they can get the same sound, wattage and specifications for $100? Ego? 'Oh, I will never tarnish my sound system with these here today and gone tomorrow products'? That is human nature when it comes to what we love. We would like to show off what we have, not what we hear!! Even if the show off is to ourselves.

I still remember when I lugged my Hsu VTF2 from the US. When I reached Chennai customs, the customs officer asked me what it was. I told him it was a sub-woofer for my HT. He looks at the name, tuts tuts, and whispers in my ear. 'Next time don't buy such trash. Get a Sony!'. Since I was so ill-informed about sub-woofers, he shooed me out with asking for any duty. Poor me!!

The good part for us at least is that some of the Asian companies are beating the pants down of established names in DACs. Companies such as Topping have improved their product so much in terms of specs and usability that established names have to seriously rethink their strategy. The bad part for us is that these Asian companies, once they attain a certain reputation, have started charging what the established companies would charge for their product. But again comes the question - we would happily pay $2000 for a Benchmark DAC. Would we pay $1500 for Topping DAC that has better specs?

Something we all need to think about. Why should I not have two Lepais with one as a standby spare? At 200, it will still be 1/5th of what I have to pay otherwise.

These are all good points venkatcr.
We will always be paying incurred cost to manufacturers, big animals eat much so we pay more to those big established brands.
I bought Topping D90 in March 2020 and this DAC is not less than any other in the market coasting way more than its price, its funny that you mentioned Benchmark above, one of my friend bought Benchmark DAC3 around the same time and he always regrets the money spent whenever he visits my place and listen D90.
I guess it is kind of preference for most of us to go with those established brands if money isn't a problem.
Truth to be told, I was also hesitant to spend around 750$ for Topping product and I give it a go as it is easy to try and return a product here if you don't like it. It turned out that I loved everything about D90 and decided to replace my Schiit DAC.
Likewise, I tried Peachtree Decco 125 SKY, PS Audio Sprout, Rotel 80WPC and XTZ Edge. Finally decided to replace my old Marantz PM6006 with XTZ and returned others.
These were not apple to apple comparisons but I was not looking for that anyway.
So I guess we need to be open for these no so well established company products and give it a go.
Reliability and after sales support might always be fishy but it is true for brands like Marantz as well!!!
 

venkatcr

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I want to know how how FX audio D 502( available in HiFi mart) fares for entry level class D amp given that it ticks all the boxes for me so far as inputs are concerned. The amp section appears to have similar claimed specifications ( TAS5342 )as that of ST TDA7498E i.e 2x108W into 4Ω . The implementation will be different I know. This for driving Infinity 89db bookshelf speakers with 6.5 inch mid bass.
HifiMart has two Fx-Audio products. There are reviews available on the Net for both. Please check them and make up your mind.
 

superczar

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Reliability and after sales support might always be fishy but it is true for brands like Marantz as well!!!

1) I have a Marantz PM-17 that has a somewhat scratchy volume knob
It's wired in pre-amp delinked mode with my AVR so it is a non-material defect for me
However if I ever decided to use it as an Integrated, the repair alone would set me back by the cost of 3X class D amps

2) With the convenience of anytime streaming, I really don't like powering up devices before I can start listening (and religiously shutting them off)
My class D streamers are left always on while with this one, I have had to make convoluted home automation arrangements for auto power on/off
Not to mention the multi second delay before playback actually starts

3) From a hobbyists' perspective, I personally feel that the subjective difference between amps are down to the respective native colorations each one has. With decent AB amps costing north of $1000, good luck experimenting and settling down unless you are really loaded.
No such issues with these D amps

What's not to love? :)
 

arunlouie

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Very nice write up Venkat!! Good to see you back!!

I was using Tripath based amp for 2.1 in Edifier for years. Even it was replaced recently with HT AVR, I am still saving it for using for future.

Now a week back started using another amp with TPA3255 based board from 3e Audio. Highly Impressed.
It was hardly 5k for the board price, my best purchase of 2020. And the quality of the board is also impeccable.
I am starting my Frugal horns again. :)
 

venkatcr

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Very nice write up Venkat!! Good to see you back!!

I was using Tripath based amp for 2.1 in Edifier for years. Even it was replaced recently with HT AVR, I am still saving it for using for future.

Now a week back started using another amp with TPA3255 based board from 3e Audio. Highly Impressed.
It was hardly 5k for the board price, my best purchase of 2020. And the quality of the board is also impeccable.
I am starting my Frugal horns again. :)
That is very nice to hear. Since you are in Chennai, I would like to drop in sometime and hear the TPA3255.

I have read a lot of nice things about the TPA3255 from 3eAudio. Getting the fully assembled amplifier is on my to-do lists. A little worried to order from Ali-Express into India. We will see.
 
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