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Old 20th May 2013, 07:35 AM   #11
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Afaik Zetex DDFA stuff is used in famous NAD MA51 and other NAD PCM/PWM full digital amps. They've got quite a good rep.

Are there any other known products that use Zetex tech
out there?


When can those EV modules be expected ??


When it comes to solutions:


1 MiniDsp NanoDigi with 1* SPDIF in - 4 * SPDIF out.

or

PC + RME AES16

feeding via SPDIF

e.g.

HifiMeDiy Fulldigital amp modules in the speaker.

That would still require 24V at least to be supplied to the speaker.
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Old 20th May 2013, 09:56 AM   #12
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Default Zetex Ealuation boards

Hi Soundcheck,

I heard a fully functional Zetex amplifier last month and it was very good.
It was configured for multi channel ( I think 5 Ch of 50 watts each Ch) and I only used two Ch, it was very close to my own power amp in overall performance, there were 10 people in the room ( large room with good layout) and most preffered the DDFA!!

My amp is a 22Kg Class A / B ( up to 5 watts class A)using a specially made UK power supply and modified power amp modules from Belles in the USA.
It sounds great but is big, hot and heavy...
The DDFA is the size of a paperback book, runs cool as a cucumber and weighs 2Kilio's!!
The fact that the DDFA also is a full blown DSP / Eq / crossover / DAC etc is just amazing.

I am now persuing a MOQ directly with Zetex in the UK and depending on the investment required, I will try to pull together a DIY forum team and set up a group buy later this year.
I will need some help with the firmware and control interface so please let me know if you will have some time in the summer?

Cheers
Derek.
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Old 20th May 2013, 11:31 AM   #13
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Quote:
Originally Posted by Overkill Audio View Post
The DDFA is the size of a paperback book, runs cool as a cucumber and weighs 2Kilio's!!
The fact that the DDFA also is a full blown DSP / Eq / crossover / DAC etc is just amazing.

I am now persuing a MOQ directly with Zetex in the UK and depending on the investment required, I will try to pull together a DIY forum team and set up a group buy later this year.
I will need some help with the firmware and control interface so please let me know if you will have some time in the summer?

Cheers
Derek.
Hi Derek,

I have been working with the Zetex amps - and have also a much improved driver stage design with galvanic isolation between the driver and output JFETS The driver high current pulses (noises) are the major problem in all switching amplifiers...
The 2 kilos are only a "dream" if you want the real SQ out of the design.
I have a prototype with a proper linear power supply (180.000uF) pr. channel that have nearly the SQ of my JFET class A amps. The difference are that I get annoyed with the switching amps as time passes by..
You cannot directly hear anything wrong, but after some weeks it is a relief to switch back to the JFET class A amps... I have made my own custom coils for output filtering etc. etc..
Have Zetex still the requirements regarding NDA etc. as they had a couple of years back ??
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Old 20th May 2013, 04:10 PM   #14
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Hi Soundcheck,

Thanks for the input. Right now I have a Mac Mini for DSP/XO hooked up to a RME UFX that I'm planning to run XLRs from to the amps in the speakers. If I'm going to run four a bundle of cables, I feel they might as well be analog so I have access to in practice unlimited DSP power.

Overkill,

Are you planning to put together an MOQ for boards or for the chips? Do you know what quantities are required? I'm working on a pair of active 4-ways and this sounds interesting to explore. I am a software engineer; I think I might be hard for me to find the time for yet another side project, but it sounds fun. What does their stack look like today and what software is in your opinion missing?

Cheers
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Old 20th May 2013, 09:28 PM   #15
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Default MOQ boards

Hi Guys,

I think it would have to be a deal on the eval boards as building up a system from the chipset on its own will be a major project.
I think both DigiKey and RS Components supply the chipsets in low MOQ, but you really have to have a lot or resource to do all the design and R&D to go from chips to finished product.

The chipsets are not under NDA but the eval boards are.

Gvr, I think the project will need a lot of software / firmware / interface development, but the end result would be worth it, pretty much game over as far as source / electronics goes, and makes the loudspeaker interface so much easier with the DSP crossovers and Eq.

Cheers
D.
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Old 20th May 2013, 09:34 PM   #16
gvr is offline gvr  United States
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I kind of agree on game over; hooking all these different products up feels like a very dated and dumb approach for small volume products since you don't care about a few unused outputs, a bit too much power, or whatever excess capacity there is, and on high volume stuff you probably want custom boards.

What software does the eval boards ship with? None?

Cheers,
Marcus
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Old 20th May 2013, 09:51 PM   #17
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Hi Marcus,

The amplifier I heard was fully functional with a good basic software and user interface, easily up to dealer / show standard, but would require some slight customisation for end user.
I am not sure if it ships with that level of "plug and play" or whether this is one of their demo units that they give out on loan to OEM's.

I hope to have a more detailed spec of MOQ / spec / support / by the end of the month.

One thing they have made clear is that they wont supply a one man band working out of his garage... So I am out! LOL
They will deal with me if I have ( a) enough cash to buy the MOQ upfront & (b) the recource to develop the product without them having to hand hold all the way... I need help from a team of DIY guys who can work together and make a group buy happen and then make the R&D a realistic project.

Even if it takes 6 months or a year ( as many DIY projects take this long) the prize is worth it.
Cheers
D.
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Old 20th May 2013, 10:03 PM   #18
gvr is offline gvr  United States
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With software/UI I meant for configuring the chip (filters/XO/etc.) The only UI I want is a volume control.
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Old 20th May 2013, 11:07 PM   #19
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Ah right, I think all the basic crossover and Eq functions are available on the eval board.

As soon as I can get up there for a visit (maybe next week) I will know more, until then I am just kind of guessing based on a short phone call with a sales guy who told me the technical DDFA guy is on holiday but he will try his best to help!

Cheers
D.
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Old 22nd May 2013, 10:56 AM   #20
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I wouldn't be interested to do complex and usally compromised DSP on a standalone system.

The DSP work should be done on the PC/server. And the digital amps which reside inside the speakers will get a plain PCM signal via SPDIF/AES/Toslink.

BTW.

Do those amps have VCC based volume control al la TI (VCC of output stage) .

To me that would be a key ingredient for a useful project. Many of the solutions I've been trying doing too much volume/gain control and driver leveling in the digital domain.

Cheers
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