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Lateral Mosfet Amplifers 250W - 2000W RMS Power Amplifier modules

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richie00boy said:
Would you care to highlight what you feel are the issues with class-d in high quality sound reproduction?


Very difficult and complex area it is not so much the sound quality which to be fair can be ok I have class d amplifiers that sound very good but when you compare them to a good linear they are lacking. It is the top end that the problem lies most are described as brittle. for bass cabinets they are superb sound ok and very effcient.

We have run our small modules along side well known class d amplifiers frankly its a no brainer

At low power it is ok high power big question mark.

The other problem is not audio but control of RFI and EMI related noise people pretend it is,nt there but it is. This leads to false switching, distortion and heat and eventually a loud smelly bang.
This problem is made worse by the fact that to produce high quality high end sound you need very fast sampling rates this just increases the suseptability to noise borne false switching

some amps have a fixed frequency so you can lock the frequencies to eliminate heterodynes others frequency shift here the problem of using multiple amps at high power becomes impossible.This problem is exacerbated if you try and add a switching PSU

I am not trying to knock switching amps have worked with them for 15 years just know their limitations.

This why they have now found their niche in mobile phones etc they are ideal for this very efficient power saving,low power not a big audio bandwidth.

It was orinally thought that they were the audio industry solution to cheap high power amps I think now most people think that claim may be a little premature
 
richie00boy said:
Prices of the amps is excellent value, I wouldn't have much left over making one myself. Some of them I couldn't even make for that cheap.



Pleased you think so we can reduce prices further for volume.


Our intention is quite simply to be the most competetive supplier in the market place it has taken 5 years and a lot of investment.

We have a lot of improvements to make yet both to product and marketing but it will all be attended to
 
noah katz said:
So what is the efficiency of your amps?

Sorry to be a pain, but whether intentional or not, your statements strike me as hyperbolic and misleading to the unsuspecting consumer.


The whole field of efficiency in audio amps is misleading every body has their own views.

I have my own particular views where a lot of the heat comes from and it is not efficiency related

Lets put it simply and I would not believe this unless i saw it

One of our prototype amplifiers runs 2 18 inch bins 15 inch tops and high ends at 1200 watts the amp is is in a 1u unit and the only heatsinking is an aluminium plate and a 40 mm fan which is not on all the time.

You should remember we are pro audio more than HI FI
 
soppelsa said:



The whole field of efficiency in audio amps is misleading every body has their own views.

I have my own particular views where a lot of the heat comes from and it is not efficiency related


In my experience, statements like this lead to a lot more discussion than they deserve, with hesitation I weigh in. As a degreed electrical engineer with 10+ years experience professionally designing switch mode power supplies, battery chargers, linear amplifiers, speaker systems, RF modulator and demodulator systems I can, with certainty, tell you that there is no question as to calculating efficiency in power amplifiers.

Whether one understands the impact of imaginary impedance and duty cycle on those calculations is up for debate, as your bass-bin experience shows.

I was interested in your lateral FETS, but honestly the marketing claims made on your web-site give me second thoughts. If I were you I would take a look at the spec sheets given out by Renesas for their lateral FETS and make sure you give all of that information.

Scott
 
SpeakerScott said:


In my experience, statements like this lead to a lot more discussion than they deserve, with hesitation I weigh in. As a degreed electrical engineer with 10+ years experience professionally designing switch mode power supplies, battery chargers, linear amplifiers, speaker systems, RF modulator and demodulator systems I can, with certainty, tell you that there is no question as to calculating efficiency in power amplifiers.

Whether one understands the impact of imaginary impedance and duty cycle on those calculations is up for debate, as your bass-bin experience shows.

I was interested in your lateral FETS, but honestly the marketing claims made on your web-site give me second thoughts. If I were you I would take a look at the spec sheets given out by Renesas for their lateral FETS and make sure you give all of that information.

Scott


I could not agree more efficiency is very difficult area some absolute baloney discussed with some class d amplifiers

we are up for advice on the mosfets any expert opinion is greatly received.

Our intention was not really to sell mosfets but completed amplifiers which we do quite successfully however we are always open to business.

We are not really trying to compete with the likes of renesas Hitachi our real aim is to take the far east on head on and in this we are succeeding taking substantial orders of them in the pro audio large volume business
 
So, you sell large quantities of "home made" MOSFETs to manufacturers in Asia? Interesting.....as I work with a company manufacturing some products in China.

Would you say your FETs are better than the 2SJ201/2SK1530 pair? At least yours are much cheaper, so thats one reason the consider using them in a larger scale.

But I would need much more extensive data on them to be able to compare things.

Any comments are appreciated! :)
 
Rikard Nilsson said:
So, you sell large quantities of "home made" MOSFETs to manufacturers in Asia? Interesting.....as I work with a company manufacturing some products in China.

Would you say your FETs are better than the 2SJ201/2SK1530 pair? At least yours are much cheaper, so thats one reason the consider using them in a larger scale.

But I would need much more extensive data on them to be able to compare things.

Any comments are appreciated! :)

Rikard you misundertand a little We do not supply this type of product to Asia for obvious reasons. It may be of interest to you as well that we will have a range of switchmode PSU to go with these modules shortly prototypes are under test now.

These prices are low volume we can improve

We actually manufacture in Europe and sell in europe.

I am not going to claim they are better but as good. Maybe we could discuss by email mike@class-d.com or phone 0044 7908 600373. If you are in Sweden no problem to come over and discuss


 
Rikard Nilsson said:
So, you sell large quantities of "home made" MOSFETs to manufacturers in Asia? Interesting.....as I work with a company manufacturing some products in China.

Would you say your FETs are better than the 2SJ201/2SK1530 pair? At least yours are much cheaper, so thats one reason the consider using them in a larger scale.

But I would need much more extensive data on them to be able to compare things.

Any comments are appreciated! :)

The difference doesn't seem to be very big:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=2SK1530YF-ND

But if you really want lateral fets these seem to be the cheapest I can find. Ampslab seems to have a pretty good price on Renesas though:
http://www.ampslab.com/trans_2sk1058.htm

They are 160V parts so won't do it for the highest powered amps though.
 
"The whole field of efficiency in audio amps is misleading every body has their own views.

I have my own particular views where a lot of the heat comes from and it is not efficiency related"

Heat comes from energy that was supplied by the AC line.

Efficiency may not be as straightforward to measure as we'd like, but it can and certainly should be, preferably at idle, a few intermediate levels, and full power.

If you didn't measure it, your claims are baseless. A cool heat sink may be due simply to good air circulation.
 
noah katz said:
"The whole field of efficiency in audio amps is misleading every body has their own views.

I have my own particular views where a lot of the heat comes from and it is not efficiency related"

Heat comes from energy that was supplied by the AC line.

Efficiency may not be as straightforward to measure as we'd like, but it can and certainly should be, preferably at idle, a few intermediate levels, and full power.

If you didn't measure it, your claims are baseless. A cool heat sink may be due simply to good air circulation.

Noah thanks for your comment and it is noted.

The coolness is not due to good air circulation because we actually do run them without fans.

Your mains idea is interesting.

An all N amplifier will run cooler than an N and P amplifier A lot of the answer lies in the heat generated in Class D amplifiers understand that and you are making progress.

We easily achieve 55% could claim a great deal more have the figures to prove it but that would just open a can of worms on here something we do not want to get involved in.


However we would say this the efficiency claims of most Class D amplifiers are baloney and probably nearer 75% on a good one.

We can approach 60%/70% and if you put in extra controls maybe more so the real difference efficiency wise between AB and Class D does not justify the amount of problems involved with class d at reasonable power levels.

There is a design of Class D amplifier which has ZVS this is a significant step forwardand does address a lot of the problems.

However if you combine a good linear amplifier with a reasonable switching power supply and all the associated controls it ends up a very close call efficiency size and weight wise.

And no way does a Class D amplifier sound as good as a linear amplifier
 
Hi!
This is a board where evidence based statements are well respected and vague talk like yours about efficiency are questioned. You statement that we are not mature enough to understand the concept of efficiency is a statement that I can´t share. Actually we do like to discuss and to find out what the truth is, and if you talk about worms in this context you better be very careful about our claims.

Efficiency is by definition the relation between the input of resources put into a process compared to the output of other (wanted ) resources enabled by the process. Of course it´s possible to measure the energy put into an amp compared to the output of energy available at the output. If there isn´t a standardized method to do just that there is still possible to obtain a result that can be claimed to reflect real life conditions. A discussion how to make comparisons between different classes of operation seems more relevant than saying that the problem is that big and people are unable to understand..... a statement that is clearly disparaging.

Quote:"An all N amplifier will run cooler than an N and P amplifier." Do you mean an amp with N-channel MOS FETs at the output? In case it´s not unique to use such an approach.

Quote:"However we would say this the efficiency claims of most Class D amplifiers are baloney and probably nearer 75% on a good one." Comment: "probably" should be verified with measurements including under which conditions the measurements were made. Hmmm "have the figures to prove it but that would just open a can of worms on here something we do not want to get involved in." Making statements without the willingness to prove them don´t impress.

In the first issue of 2004 the German magazine Audiophile reviewed an advanced class D amp; Audio Physics Mono which got a top verdict. According to the magazine it had some features like a circuit patented by Mircea Naiu and the amp was indeed expensive. But the appearance of it may point at the possibility to address the problems involved with Class D amps even in a high end environment.
 
The golden mean said:
Hi!
This is a board where evidence based statements are well respected and vague talk like yours about efficiency are questioned. You statement that we are not mature enough to understand the concept of efficiency is a statement that I can´t share. Actually we do like to discuss and to find out what the truth is, and if you talk about worms in this context you better be very careful about our claims.

Efficiency is by definition the relation between the input of resources put into a process compared to the output of other (wanted ) resources enabled by the process. Of course it´s possible to measure the energy put into an amp compared to the output of energy available at the output. If there isn´t a standardized method to do just that there is still possible to obtain a result that can be claimed to reflect real life conditions. A discussion how to make comparisons between different classes of operation seems more relevant than saying that the problem is that big and people are unable to understand..... a statement that is clearly disparaging.

Quote:"An all N amplifier will run cooler than an N and P amplifier." Do you mean an amp with N-channel MOS FETs at the output? In case it´s not unique to use such an approach.

Quote:"However we would say this the efficiency claims of most Class D amplifiers are baloney and probably nearer 75% on a good one." Comment: "probably" should be verified with measurements including under which conditions the measurements were made. Hmmm "have the figures to prove it but that would just open a can of worms on here something we do not want to get involved in." Making statements without the willingness to prove them don´t impress.

In the first issue of 2004 the German magazine Audiophile reviewed an advanced class D amp; Audio Physics Mono which got a top verdict. According to the magazine it had some features like a circuit patented by Mircea Naiu and the amp was indeed expensive. But the appearance of it may point at the possibility to address the problems involved with Class D amps even in a high end environment.


Strange sort of reply really says very little maybe attempting to be a little disparaging yourself.

However I do not intend to get into a bun fight with you.


Suggest you go and put your hand on one of these so called super efficient class d amplifiers and explain what all the heat is

Reality is much sounder that talk and speculation
 
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