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Hifisonix kx-Amplifier
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Old 11th November 2018, 05:14 PM   #21
maty tinman is offline maty tinman  Spain
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KEF Q100, graphs measurements by kimmosto

Coaxial drivers for ultimate speaker?

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KEF LS50, graphs measurements by kimmosto

Coaxial drivers for ultimate speaker?

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KEF Q100 with only first order crossover. It is more lineal... always.
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Old 11th November 2018, 05:15 PM   #22
Vunce is offline Vunce  United States
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Hifisonix kx-Amplifier
Default KX Amplifier is Born

Hello Bonsai!! Your timing is impeccable, I’m so glad you started this thread for the KX amp. My build is almost completed, the Walnut wood top and front panel need to be fabricated along with placement of switches. In the meantime this newborn is singing away!! Here are a few details: Pair of Antek AS-3224 transformers w/covers Pair of Ripple Eater psu’s This combination gives me final voltages of -28.5vdc/+28.1vdc loaded. The dc offset varies from -5mV to +5mV when the KX is at operational temperature.

The reclaimed heat sinks are large enough to mount both the psu and amp board without a problem keeping the heat dissipation under control even when running at the high side of 28vdc. I do not have experience with your other amplifiers (SX/NX) so unfortunately I can’t compare to them. In my short listening time, the soundstage is very impressive. Music seems to flow from well outside the speaker “box”. The bass is very solid and articulate. Definitely not an amp that should be cranked up in an upstairs apartment, the downstairs tenants might think a thunderstorm is approaching

On my test bench, the speakers are low efficiency 4ohm bookshelf type. I couldn’t hear any hum/noises. Now, I have the KX in my main rig paired with very efficient 8ohm floorstanders and there is a slight hum that’s audible. I’ll have to get that worked out. Thank you Bonsai for sharing a wonderful amplifier project, I’m really going to enjoy this one.

And.... WELCOME BACK!!
Vunce

I can build the amp but can’t flip the pictures, I apologize.
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Old 11th November 2018, 05:22 PM   #23
maty tinman is offline maty tinman  Spain
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I saved the article: http://www.medleysmusings.com/kef-q1...-unit-testing/ now the site is out.

KEF-Q100-drive-measurements-by-medleymusings.zip, 740 KB:

http://maty.galeon.com/WP-imagenes/k...leymusings.zip
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Last edited by maty tinman; 11th November 2018 at 05:24 PM.
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Old 11th November 2018, 06:46 PM   #24
xrk971 is offline xrk971  United States
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Hifisonix kx-Amplifier
Nice work Vunce! Wondering how it compares to Alpha BB?
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Old 11th November 2018, 07:30 PM   #25
maty tinman is offline maty tinman  Spain
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Default Ripple Eater PSU / Capacitance multiplier.

Quote:
Originally Posted by Vunce View Post
I do not have experience with your other amplifiers (SX/NX) so unfortunately I can’t compare to them. In my short listening time, the soundstage is very impressive. Music seems to flow from well outside the speaker “box”. The bass is very solid and articulate. Definitely not an amp that should be cranked up in an upstairs apartment, the downstairs tenants might think a thunderstorm is approaching...
Simple Ripple Eater PSU for the sx and kx-Amplifiers

http://hifisonix.com/simple-ripple-e...kx-amplifiers/

Quote:
...I used a ripple eater on the e-Amp to clean-up the supply to the amplifier front end and got better than 30 dB ripple rejection, so the technique works extremely well in practice.
Harmonics

Click the image to open in full size.

Click the image to open in full size.

For me it is very important to clean the noise because I suffer from a terrible electrical grid at home. I was struck by the Capacitance multiplier / Ripple Eater PSU. Together with my gadgets it can be the definitive solution to my problems, I think/hope.

Each time I managed to lower the noise, the soundstage increased, the details and music filled the room more.
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Old 12th November 2018, 01:11 AM   #26
PRR is online now PRR  United States
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Hifisonix kx-Amplifier
Quote:
Originally Posted by maty tinman View Post
...Calculators / Audio / Acoustics / SPL...
You set Distance to 3 meters (10 Feet).

Inside a domestic room, the Critical Distance is more like 3 or 4 feet, ~~1 Meter. Closer, SPL rises; further, and SPL hardly drops, due to reverberant field "filling" the room.

The direct sound at 3 meters will indeed be 88.2dB SPL, but the *total* sound at your ears will be 6 or 8 dB higher, ~~95dB SPL.
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Old 12th November 2018, 09:27 AM   #27
Bonsai is online now Bonsai  Europe
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Hifisonix kx-Amplifier
Quote:
Originally Posted by Mark Johnson View Post
I wish the square wave tests (page 25) weren't presented with oscilloscope bandwidth limiting turned on. There might be a bit of overshoot or underdamped ringing, which BWLIMIT prevents us from seeing.

Just barely visible is a smidgen of overshoot: the smoothed, BWLIMITed yellow trace just barely overshoots enough to kiss the upper dotted line. Then it recovers from overshoot and settles down to its final asymptotic value. Click on the white "X" at lower left to see the image full size and undistorted. The overshoot is also visible in the zoomed out (20usec/div) picture on the same page.

I also wish there were 3A or 5A "catch diodes" across the Zobel networks, to protect the output transistors when clipping into crazy reactive loads. And I wish the "OMG a rail is dead" safety diodes {Cordell section 15.3, p.325} D2 and D3 had a continuous DC current rating higher than fuses F2 and F3. I personally prefer to use the 10A04 thru hole diode in those positions; I don't mind paying 2 x $0.76 to buy them.

_
All good points - perhaps something to consider for a future spin of the board. That said, I've not had any problems on the 10 or so kx and sx board sets I've personally built, or had any reports of problems on any of the other builds. Re the 'OMG' diodes, I've popped the supply fuses on the sx-Amp quite a few times during development without issue (the OP devices are hugely overrated on the recommended supply rails). I guess however the case would be different if one of the OPS transistors were to fail.

Overshoot - ok - we can split hairs over it but not an issue in use and remedied with a change in resistor and/or cap if someone believes its objectionable. In practice its a non-issue.

Have you looked at some of the square wave plots on Stereophile (tube and solid state)?

Last edited by Bonsai; 12th November 2018 at 09:43 AM.
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Old 12th November 2018, 09:33 AM   #28
Bonsai is online now Bonsai  Europe
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Hifisonix kx-Amplifier
Quote:
Originally Posted by Vunce View Post
Hello Bonsai!! Your timing is impeccable, I’m so glad you started this thread for the KX amp. My build is almost completed, the Walnut wood top and front panel need to be fabricated along with placement of switches. In the meantime this newborn is singing away!! Here are a few details: Pair of Antek AS-3224 transformers w/covers Pair of Ripple Eater psu’s This combination gives me final voltages of -28.5vdc/+28.1vdc loaded. The dc offset varies from -5mV to +5mV when the KX is at operational temperature.

The reclaimed heat sinks are large enough to mount both the psu and amp board without a problem keeping the heat dissipation under control even when running at the high side of 28vdc. I do not have experience with your other amplifiers (SX/NX) so unfortunately I can’t compare to them. In my short listening time, the soundstage is very impressive. Music seems to flow from well outside the speaker “box”. The bass is very solid and articulate. Definitely not an amp that should be cranked up in an upstairs apartment, the downstairs tenants might think a thunderstorm is approaching

On my test bench, the speakers are low efficiency 4ohm bookshelf type. I couldn’t hear any hum/noises. Now, I have the KX in my main rig paired with very efficient 8ohm floorstanders and there is a slight hum that’s audible. I’ll have to get that worked out. Thank you Bonsai for sharing a wonderful amplifier project, I’m really going to enjoy this one.

And.... WELCOME BACK!!
Vunce

I can build the amp but can’t flip the pictures, I apologize.
Wow - quite a build Vunce!


Trust it goes well and you'll have it up and running shortly. Once you have finally wired it up f you still have noise issues we can sort it out. Remember to twist the power cables from the transformer to the PSU board, and from the PSU to the amplifier boards. Same for speaker terminals to amplifier boards. Keep input cables well away from power supplies and associate wiring.

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Old 12th November 2018, 11:43 AM   #29
zman01 is offline zman01  Bangladesh
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Hifisonix kx-Amplifier
Vunce,

Impressive build, congratulations!

Those heat-sinks look like they mean business ; love the clean layout and wiring, well executed. The chassis dimensions and red glow remind of high end gaming rigs!
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Old 12th November 2018, 02:59 PM   #30
maty tinman is offline maty tinman  Spain
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Default Schaffner FN 9244B IEC inlet filter

Vunce, I can see a RF/EMI IEC inlet filter in your DIY. Which?

Years ago I was researching about it and those who had better specifications were those manufactured by Schaffner, and by far. I have a few in my two systems.

Schaffner FN 9244B 3A

https://www.schaffner.com/product-st...heets/fn-9244/

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Click the image to open in full size.

Click the image to open in full size.

* B = medical
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