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Guardian-86 and Guardian-686: High-End Speaker Protection Circuits

tomchr

Member
Paid Member
2009-02-11 12:58 am
Calgary
www.neurochrome.com
Mains is ±235V with 2× 25 VAC 150 VA power transformers with ±27.5 of secondary output what gives me ±36.5V out of V Power-686.
I had 2×24 VAC Hammond before, which I had on a shelf from other project, but it was so bloody noisy and I replaced it with Toroidy ones.
Toroidy makes good stuff.

I'm still puzzled that you had issues with speaker pops on the MOD286. I've built several and they've all powered up and down quietly. Are you using an unbalanced source and pseudo-differential connection by any chance?

Tom
 

tomchr

Member
Paid Member
2009-02-11 12:58 am
Calgary
www.neurochrome.com
Now this... The Guardian-86 Rev. 2.0 just launched.

Major improvements over Rev. 1.0:
  • Works without modifications on any amp power by ±15 to ±90 V (or single-ended amps powered by +15 to +90 V).
  • Works with all amplifier types: Single-ended and bridged/BTL.
  • Smaller footprint (40 x 45 x 27 mm; W x D x H).
  • Automatic sensing of the power supply and automatic disabling of the output once the power supply voltage drops to 2/3 of its nominal value. This eliminates clicks and pops on power-down.
The Guardian-86 is $99/each and is only available as a fully assembled module. This allows me to provide a better product at a lower cost to a broader market. The Guardian-86 is a mono board. Two are needed for stereo.
Guardian-86_R2p0_CC.jpg


The Guardian-686 will be discontinued once the current stock has sold. I have six fully assembled Guardian-686 in stock and on sale at $169/each (reg. $199/each). I also have a good handful of the bare boards in stock. Shop the sale here: https://neurochrome.com/products/guardian-686

You can read more about the Guardian-86 here: https://neurochrome.com/products/guardian-86

Tom
 

tomchr

Member
Paid Member
2009-02-11 12:58 am
Calgary
www.neurochrome.com
The Guardian-86 Rev. 1.0 and Guardian-686 do not have the auto-sensing of the supply voltage. You set the trip point with a zener diode, but it's not super precise. Basically the Guardian browns out and turns off. In the Guardian-86 Rev. 2.0 there's a comparator that compares the supply voltage with 2/3 of the sensed nominal voltage. Once the power supply crosses that 2/3 threshold, the MOSFETs are turned off and the speaker is disconnected.

The Guardian-86 Rev. 1.0 and Guardian-686 will work without modifications up to 45 V. If you want to go higher than that you need to swap a zener diode.

Tom