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Old 30th November 2001, 09:43 AM   #11
ergo is offline ergo  Estonia
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I wondered the same and then found

http://www.lcaudio.dk/zappulse.htm

It danish, but you can read out the useful....

Ergo
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Old 30th November 2001, 10:21 AM   #12
Helix is offline Helix  United Kingdom
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7 or 8 in one case would be good for AV use. But then you will need a switch mode power supply, because a traditional one would be far too big. Actually you could get a couple of 1kw trannies in a 3u case, but then the amps and the smoothing caps will be a squeeze (don't want to compromise PS caps just because of lack of space)
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Old 8th December 2001, 03:28 AM   #13
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But I really dont understand what is the usage for the onboard LCXO2 on the Zappulse? Anyone can explain?
Is it accept the digtial in or something?

Actrally I tried this amp at the office of their agency in Koren. The phototype which they testing havent the LCXO2 onboard. The sound compare with the Lcaudio poweramps "T.E.M" and the class A 50W. This Zappulse is lost! But when they tell me it just run-in about 24 hours only! Then I have supprise. Actrally the bass of Zappulse not heavy enough than the Class A and the T.E.M. But other just lost little only! It is terrble that it seems really powerful too! I think when it hae more time to run-in, maybe really great! And the price is attractive too!!!
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Old 15th December 2001, 07:56 PM   #14
km is offline km
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Smile pwm amplifiers

hi.

i have some news for those of you interested in pwm amplifiers.

we can now sell our demo boards as samples and the prices are reasonable (i think).

recent listening tests has shown that they actually sound better than other class-d amps involved in the tests (they may have better specs though , hehe)

we will be conducting a series of demos where we compare to other "digital" amplifiers and some cool a/b designs as well.

bye k madsen

(link to info : www.cadaudio.dk/pwmaudio.htm)
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Old 15th December 2001, 11:46 PM   #15
Dave is offline Dave  New Zealand
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Default Digital Amp - Not Class D

I think the way to go is a true digital amplifier - not Class D.

A true digital amp accepts a digital input, converts it with a DSP or similar to a pulse stream which drives the output switches. There is no feedback and no low level analog. The volume is adjusted by changing the voltage level on the output stage supply rails.

I think Texas Instruments have come out with a true digital amp chip based on the tact audio amp. Has anyone tried it?
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Old 19th December 2001, 10:30 PM   #16
km is offline km
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Smile digital amplifier

hi.

there are many analog sources out there

i agree that a "true digital" amplifier , meaning a pcm to pwm chip and a pwm amplifier sounds interesting , we will take a closer look at it for sure.

i also think its fair to say that you can get quite good results with a good dac and an analog imput pwm amplifier.

the difference between the two schemes arent that big really.

we will perform a series of demos/listening tests with high quality pwm amplifiers (in copenhagen) if any of you have an interest in this or want to do the same please contact me/us and lets see what we can do.

regards - k madsen - www.cadaudio.dk/pwmaudio.htm
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Old 19th December 2001, 11:04 PM   #17
Nisbeth is offline Nisbeth  Denmark
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Hi there

Hatasa: As far as I can understand, the LCXO2 on the board is so you can sync the amp with the clock in your CD/DVD-player, which should eliminate jitter(??). The amp will not accept a digital input.
BTW, LCaudio.com allows you to download the datasheet/whitepaper which I think is in english (havent bothered to DL'it, since I'm Danish ;-)

For those who wanted to know: The normal price for the Zappulse is app. 5000 DKK (~600USD/670 Euro). However, a stereo set of evaluation boards is now sold at the introductory price of 2500 DKK (~600USD). The kit includes two amp. boards (two channels) + 12 V gate supply. You need a 700 VA tranny and caps to build a functioning amp.

Regards,
Uffe
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Old 19th December 2001, 11:23 PM   #18
km is offline km
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Default digital amplifier

hi.

have you heard the lc amps?

how are they regarding emc?

how are they regarding power supply ripple rejection?

bye k madsen - www.cadaudio.dk

ps. $600 "normal price"?? hehe
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Old 31st December 2001, 05:46 AM   #19
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Default semi OT :

Helix, what is the "new" class B topology you referred to in your post? Can you point me to any schematics/info on it?
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Old 1st January 2002, 04:55 AM   #20
Helix is offline Helix  United Kingdom
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yes i can, please hold on a day or two, while i'll recover from new year's day
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