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β24 Mono Block from South Africa

beta24

Re: β24 Mono Block from South Africa

Postby Hasren » November 16th, 2019, 1:41 pm

Thank you...
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Re: β24 Mono Block from South Africa

Postby Hasren » January 14th, 2020, 8:24 am

Quick Update: I received the new matched JFETs quads (thanks Ti), installed and did the initial set-up with ease and it sounds superb. The RLED changed to 100KOhms and they light beautifully. Considering that I am driving 4Ohm speaker load I upgraded the unregulated trafo from the 300VA Novutem Telema to a 500VA Block Trafo. The Novutem trafo had a buzzing sound, so I had to bypass the SSR and connected the Block Trafo directly to the empty side of the MJN2CE-DC12. However, I am experiencing a bit of a problem with the amp sometimes not powering on. I don't know if this is because I am using one relay (MJN2CE-DC12) for both draining the capacitors (through the 30 Ohm 25W bleeder resistor) and also for a soft start function? For filtering Capacitors am using the Nichicon LNR1H153MSE (2x15000uF 50V). Otherwise, the 500VA Block trafo is dead quiet no audible Hum/Buzz at all. In terms of sonic difference, I cannot detect any advantages of a bigger trafo (300VA vs 500VA) particularly at my listening level (which is moderate). I have received the board for the second channel and will give updates of how that goes.
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Re: β24 Mono Block from South Africa

Postby amb » January 14th, 2020, 12:17 pm

Hasren wrote:...
I don't know if this is because I am using one relay (MJN2CE-DC12) for both draining the capacitors (through the 30 Ohm 25W bleeder resistor) and also for a soft start function?

Can you post a diagram of how you wired this up? It is not clear from your description.
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Re: β24 Mono Block from South Africa

Postby Hasren » January 15th, 2020, 5:03 am

Please find a quick hand-drawn diagram. I hope it will be clear enough. The MJN2CE-DC12 is drawn at a de-energized state.
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Re: β24 Mono Block from South Africa

Postby amb » January 15th, 2020, 11:18 am

I don't see any "soft start function" you referred to. But what you've drawn seems reasonable since you have a monoblock, so one pole of the MJN relay was unused, which you now use in lieu of the SSR to switch the mains power for the transformers.

If the amp fails to turn on fully when you press the power button, it could be because you're getting a mains voltage drop condition. When the amp turns on there is a large surge current (to set up the magnetic field of the transformers, and to charge the bulk caps). If your AC mains is coming over a long wire (house wiring and power cord), the surge current will create a voltage drop glitch that could de-activate the ε24, turning the amp back off.

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Re: β24 Mono Block from South Africa

Postby Hasren » January 15th, 2020, 11:56 pm

Mmm "Soft-start" I meant to mean T1 T2 connections ;) . Thank you very much. Your assessment of the mains and the long power cord is spot on. It really makes sense. Otherwise, it wasn't a major concern. I am enjoying my amp :D although for now, I have paired it with one channel of the NAD M25. I can't wait to complete the second monoblock. :lol:
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