Looking for advice with D class amplifier choice

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Dear DIY colleagues.

I am product designer living in Prague and i am designing small loudspeakers for PC/ Ipod/Mp3 use.The goal is perfect sound quality and rasonable volume with lowest possible distortion in nearfield use. So far i have chosen the speakers, i will use Dayton ND-90 8 ohm version (higher sensitivity, more linear at upper frequencies than the ohm version ) one per side, probably closed enclosure.
I have searched the possibilities of a good amp for this setup and i have found out these three finalists. (I decided that i will need more than basicall T-Amp power because the distortion around 10 percent is quite high on full power and the Daytons are quite insensitive.
I have found three suitable amplifiers with power starting 2x5O W
The last two of them are with USB and D/A converter, but being not educated in audio conversion i cannot judge how good/bad these converters can be.

1)Hifimediy for 60 Usd

2) Wholesale TDA8920 Product-TDA8920 CLASS D AMP WITH USB DAC AND HEADPHONE AND SMPS
for Usd

3) The third is new prototype of 2x 125 watt Sinewawe amplifier, offered to me from Xinlai. I dont know how to post a pdf file and it is nowhere on the internet :confused:
It is called G 100 mini amplifier and it comes with USB input, 3,5 mm input and it is in nice aluminium box with controlls. The spec say that it has:
TAS 5613 and SMPS 90-265 Vac...

I will be very glad for your opinions and recommendations.

Thank you
 
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Dear DIY colleagues.

I am product designer living in Prague and i am designing small loudspeakers for PC/ Ipod/Mp3 use. The goal is perfect sound quality and rasonable volume with lowest possible distortion in nearfield use.

Certainly there is some debate as to what "perfect sound quality" encompasses, but reasonably efficient speakers and a D-amp is a very good starting point to achieve your goals.

... I will use Dayton ND-90 8 ohm version (higher sensitivity, more linear at upper frequencies than the ohm version ) one per side, probably closed enclosure. ...

I would suggest you obtain an impedance curve for any loudspeaker you are considering. The common practice of designating speakers by manufacturers as "8 ohm" or "4 ohm" is in reality a broad generalization that does not really tell us much.

Check the curve for minimum impedance and at what frequency it appears, and insure it is above the amplifier's minimum recommended impedance. Also check the phase curve superimposed on the impedance curve. A combination of low impedance and large phase swing at a given frequency (typically @ a low frequency) is by definition a difficult load; choose another speaker in that case.

By way of example I have included a link of a loudspeaker chosen more-or-less at random that exhibits a difficult load and a brief explanation, which provides a good starting point by way of understanding the issue, and in choosing an appropriate driver.
Focal Maestro Utopia - Stereophile - measurements


I have searched the possibilities of a good amp ... I decided that i will need more than basicall T-Amp power because the distortion around 10 percent is quite high on full power and the Daytons are quite insensitive.

Generally speaking you should not pay much attention to the 10% THD value. This is simply a common specification point for evaluation. Pay attention to the lower THD @ x ohms value (say, at less than 1%) = x watts RMS specified ... this will be your maximum design estimated output power assuming appropriate power supply. Also, for near-field use, you will need much less power than for in-room use.

Since loudspeaker choice is vast and amplifier power is relatively expensive, you should choose a more efficient speaker where possible.

I have found three suitable amplifiers with power starting 2x5O W
The last two of them are with USB and D/A converter, but being not educated in audio conversion i cannot judge how good/bad these converters can be.

1)Hifimediy for 60 Usd

2) Wholesale TDA8920 Product-TDA8920 CLASS D AMP WITH USB DAC AND HEADPHONE AND SMPS
for Usd

3) The third is new prototype of 2x 125 watt Sinewawe amplifier, offered to me from Xinlai. I dont know how to post a pdf file and it is nowhere on the internet :confused:
It is called G 100 mini amplifier and it comes with USB input, 3,5 mm input and it is in nice aluminium box with controlls. The spec say that it has:
TAS 5613 and SMPS 90-265 Vac...

I will be very glad for your opinions and recommendations.

Thank you

Re-evaluate those choices based on the lower THD = output power rating as outlined above. 50W RMS is in all likelihood more than enough power for near-field use ... you could get by with 10~15 W with appropriate sensitivity speakers. Use this online SPL calculator to determine adequate amplifier requirements. 100 dB SPL at near-field is very loud. For best imaging, choose a loudspeaker with smooth and wide off-axis response curves.
 
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Having looked at the specifications for the Dayton speaker you mentioned, two things stand out.
One ... very low sensitivity of 82 dB 1w/1m
Two ... reasonable phase/impedance curve

You may want to explore a different driver with higher sensitivity. You may find increasing the driver size slightly (say, 4" or even 5") gives you more choices. Alternately, you can consider an array of 2 or more of these drivers (adds +3dB SPL with 2 per side, also if wired in parallel [net 4 ohms] you will obtain greater power output from the amplifier, assuming power supply is adequate).

Without regard to sound quality (which would require evaluating a sample) the TDA8920 item's overall specifications seem attractive for your purposes. The Hifimediy unit will require an adequate power supply and some ancillary parts, which adds to it's overall cost, and again an evaluation would be required for sound quality assessment.

Broadly speaking all these amp modules (and most others you will find) rate power and THD at 1 kHz only. Since this is a very easy load it may not be representative of actual output power over the normal audio range (20 Hz ~ 20 kHz with varying phase/impedance). It would be wise to assume somewhat lower power output in actual use with full-frequency content and an actual speaker load.
 
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Johnny2Bad :
Thank you for your very helpful insight, i am uneducated in electronics.. If i understand it correctly, you are pointing out that the impedance is frequency related and and the manufacturer info is approximated value. I was somehow attracted with this Dayton driver, i have read some article about Murphy line array which i liked and i was also thinking about trying to make prototypes of a speakers with more drivers per side later . I did not wanted to go for a bigger driver, because i wanted the speaker to be slim considering also the "on table" use. About the sensitivity-i did not pay attention to it, because i have seen that you can easily buy 2x50 or 2x80 W class D amp for around 60 USD and the quality looks acceptable. I also had in mind that the speakers should be somehow universal and able to play at higher volumes when not used as nearfield. So i like the option to use two per side preferably, the box will be thinner and that is better for me. Can you, please have look at this G100 Amp with USB DAC and tell me what you think comparing to my other choices above ? It is new model and they are offering it for unbelieveable 60 dollars.
Maybe i will made the speakers passive and the amp will be next to the computer on the table.. Thank you very much !
 

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Johnny2Bad :
Can you, please have look at this G100 Amp with USB DAC and tell me what you think comparing to my other choices above ? It is new model and they are offering it for unbelieveable 60 dollars.
Maybe i will made the speakers passive and the amp will be next to the computer on the table.. Thank you very much !

Again, it is difficult to say without a closer examination and audition. There is also the issue of who you are buying from and their policies should something go wrong. Finally I find that when obtaining a product online, you should give serious consideration to shipping costs and whatever shipping issues that may apply to your unique situation.

When I am searching for product online, I first go to the shipping policy page before I even consider looking at the products themselves, and often I simply leave at that point. Sometimes that plays a big role in what products we eventually choose.

Your particular situation will vary, but it's worth investigating as it can impact your shipment transit time and the project cost significantly. Do some research and determine which carrier and method is best, and only deal with vendors that offer those options.

Considering the speakers you seem to prefer to use, it appears any of the units you've mentioned will have acceptable performance, assuming they work as advertised. It is difficult to assess build and parts quality from photos, but it does appear the units you are considering are built to a price. $60 may not be a bargain if the unit is not reliable, for example.

The speakers you are looking at are typical of store-bought mp3 players, plasma tv sets, etc. If you consider the average flat screen TV to have adequate sound quality, then you are probably on the right track.

If you do choose a particular unit, please post back and let everyone know what it's all about. A few good photos are always appreciated as well ... chinese suppliers seem to put a great effort in saving bandwidth by using relatively low quality images.
 
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Again, it is difficult to say without a closer examination and audition. There is also the issue of who you are buying from and their policies should something go wrong. Finally I find that when obtaining a product online, you should give serious consideration to shipping costs and whatever shipping issues that may apply to your unique situation.

When I am searching for product online, I first go to the shipping policy page before I even consider looking at the products themselves, and often I simply leave at that point. Sometimes that plays a big role in what products we eventually choose.

Your particular situation will vary, but it's worth investigating as it can impact your shipment transit time and the project cost significantly. Do some research and determine which carrier and method is best, and only deal with vendors that offer those options.

Considering the speakers you seem to prefer to use, it appears any of the units you've mentioned will have acceptable performance, assuming they work as advertised. It is difficult to assess build and parts quality from photos, but it does appear the units you are considering are built to a price. $60 may not be a bargain if the unit is not reliable, for example.

The speakers you are looking at are typical of store-bought mp3 players, plasma tv sets, etc. If you consider the average flat screen TV to have adequate sound quality, then you are probably on the right track.

If you do choose a particular unit, please post back and let everyone know what it's all about. A few good photos are always appreciated as well ... chinese suppliers seem to put a great effort in saving bandwidth by using relatively low quality images.

Thanks for your help ! I will post some photos of the amplifier when it arrives. Please,if you do know about some fullrange speaker of similar size and affordable price that will be significantly better for my purpose, i am open to any sugestions. About the flatscreens-i honestly almost never really listened to flatscreen own speakers, they sounded mostly terrible. At home i have only projector and computers, no TV. I may be wrong, but i somehow doubt that some 1000 USD flatscreen will have 4 inches fullrange driver with neodymium magnets, i think that the speakers they are putting in are smaller and also the cheapest 2 USD papercones in thin plastic.

Thanks again for your reply.
 
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having the same question

hello,
everybody,

i have actually the same question, i'm looking for a very good cheap amp.
at this moment i have a ta2020 (i have it since 2006), and i like it, but now these days there is better so i'm on the search for something new.

i can easily live with 15 watt per channel, more is great, less is okee, (but no less then 10w).

i'm looking for a super sound quality, when it comes down what speakers it will drive, i cannot say, i have a few.

every time i open a topic where somebody is looking for a new amp, i find out
that there a even more models and shops ...

So here are so questions

1)which chipset is considered as best sounding ? a tp2050, ta3020 ....
or something else, like mentioned above : the cd224

2)which seller offers a great package, i know you can buy a tp2050 at various places, some places it is stuffed with great components AND a great DESIGN
(i have red that that is the reason why 41hz amps cost more than the sure)

3)which amp has great support, this is important if i wanna teak it further, what i most of the time do..


things i have looked at

hifimedia or a nick12.. model (tp2050, stereo)
41hz amps
sure
and 5 minutes ago cda224,

thanks so much
greetz
 
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