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PostPosted: 17 Jul 2010, 10:50 
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Nice presentation of the pics.
Kramme, pls post some build pics of your ZCA once you start the project !

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PostPosted: 17 Jul 2010, 13:12 
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dtsup1 wrote:
Nice presentation of the pics.
Kramme, pls post some build pics of your ZCA once you start the project !

Pics of the build, yes when the build is going on ...it seems i'll have to wait for the resistors :bawling:

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PostPosted: 20 Jul 2010, 15:18 
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A little update...ZCA has been playing non stop for 10 days now. Yup, one tiny MOSFET working it's BUTT OFF 12 hours a day to provide great music for the whole family. Even mum knows how to use the system!!

Guess what...nothing changed over 10 days. NO break in/burn in was involved here and amazingly the amp sounded superb from the 1st minute of play till now. Perhaps it has something to do with the cheap caps I used requiring no break in at all.

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PostPosted: 21 Jul 2010, 09:44 
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dtsup1 wrote:
A little update...ZCA has been playing non stop for 10 days now. Yup, one tiny MOSFET working it's BUTT OFF 12 hours a day to provide great music for the whole family. Even mum knows how to use the system!!

Guess what...nothing changed over 10 days. NO break in/burn in was involved here and amazingly the amp sounded superb from the 1st minute of play till now. Perhaps it has something to do with the cheap caps I used requiring no break in at all.


Sounds great ...it seems you've got a lot of fun with the ZCA.

I've found one new ZCA at diyaudio.com's site ..added yesterday, by tubem :P

http://www.diyaudio.com/forums/solid-st ... t-amp.html

Also roger_lew's build, from march is a beauty, i like it 8-)

http://www.diyaudio.com/forums/solid-st ... ost2115577


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PostPosted: 21 Jul 2010, 09:58 
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Thanks Kramme. More ZCA builders !!
I have seen Roger's build before. Notice how both builds take steep measures to ensure proper cooling without the use of a fan. Roger's comments are spot on. Im guessing the ZCA has predominant 2nd order harmonic distortion and that is why it is more pleasant to listen to.

I'm enjoying the amp so much that I'm currently building more efficient speakers specially for the ZCA.

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PostPosted: 21 Jul 2010, 10:46 
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dtsup1 wrote:
Thanks Kramme. More ZCA builders !!
I have seen Roger's build before. Notice how both builds take steep measures to ensure proper cooling without the use of a fan. Roger's comments are spot on. Im guessing the ZCA has predominant 2nd order harmonic distortion and that is why it is more pleasant to listen to.

I'm enjoying the amp so much that I'm currently building more efficient speakers specially for the ZCA.

Yep i've seen this build with a fan, but i think it's a sin. I want to make use of large heatsinks where both diode bridge, the 50 W resistors and Mos-Fet transistors can be mounted.

About speakers ...what have you got in mind ? i guess wide range drivers as Fostex, Lowther and Coral, would be great for this amp.


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PostPosted: 21 Jul 2010, 11:33 
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Umm.. I tried some fullrangers ; Hemp acoustics FR4.5C(92dB) and FR8C(96dB). The detail retrieval was too good and unfortunately this made both the midrange regions a little harsh. This forced me to add a baffle step/notch filter but I felt it killed the music. Also I didn't fancy the bass output of those drivers as they have trouble blending in with my sub.

This amp also has very good bass response and I wanted to use an upcoming 2 way MTM with dual 8'' Scanspeak drivers. Hoping for 91-92dB/m/watt with in room F3 of around 30Hz. This should be easy as the 8'' have an Fs of 23Hz.

One issue with the ZCA. I noticed that it doesn't like high inductance midwoofers and large air-core/iron core inductors in the bass drivers. The damping factor is probably low. With my other 200W aussie Nxv200 amp, they had a supreme grip on the bass drivers. Ironically, it had no problems driving a 4ohm load speaker to satisfying levels 2-3m away.

Depending on the speakers you have in hand, I would recommend trying a fullrange driver first.
Fostex FE206En looks like a superb choice but you need a horn loaded enclosure :shock:
Better still you can just build it for your OB speakers !!

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PostPosted: 21 Jul 2010, 14:41 
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Hi Dinesh

I've never listened to Hemp but a friend told me, that he didn't like the sound of them and if he says so i believe something is wrong. Have you ever heard Fostex FE 167E ? I think it sounds okay.

I wouldn't use the ZCA build for my OB's ...i've got a DIY build with Mos-Fet's SK135/SJ50 to handle those. The ZCA i am working on, should be used with an easier load. But who knows, maybe the ZCA will create a need and some new loudspeakers will have to be build, just for the ZCA :mrgreen:

I would like to listen to Fostex FE206, when it's possible.


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PostPosted: 21 Jul 2010, 22:35 
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Hi Kramme,

The 4'' hemp actually sounds better than the 8'' hemp. (both not using any bafflestep).
People either loved or hated the hemps. The 8'' was my first ever speaker , thus it has some sentimental value and I have kept them ever since.

I have owned a pair of Fostex FE167E in 20L bookshelf speakers. They were very enjoyable. Bass had a very nice punch but nothing much below 40Hz. The whizzer cone imparts a sonic signature. I call it a "quacky" tone. Same thing for the 8'' hemp.

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PostPosted: 22 Jul 2010, 21:58 
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dtsup1 wrote:
Fostex FE206En looks like a superb choice but you need a horn loaded enclosure

Here are some photos of my Fostex FE206E back loaded horn.
They are great with lighter music. You don't get deep bass, but very solid and full from 50 Hz up. They are bright and somewhat forward. I've heard a lot of diy phase plugs and they all are an on axis improvement. :twisted: One of these days I'll do surgery on my drivers.
Cheers

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