Cyrus 2 + PSX as a Subwoofer Amp

This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Morning all

I'm currently building a 'resto-modded' all 80's Cyrus set up, with a fully active digital crossover, DACs and PSU built in to two refurbished Cyrus tuner cases. The idea is to have my Mission 770 Freedoms actively driven from a Cyrus 2 each. I'm also building an infinite baffle subwoofer into (or under) my lounge floor which at the moment is going to use 2 15" 4R woofers(!). I need a fair bit of grunt for these (or at least I think I do) and to keep the Cyrus theme going i was going to build some class-D amps into another Cyrus case, something like those L15, L20 or L25D modules maybe? But i've just acquired a rather tasty Cyrus PSX and i'm wondering how best I can put this to use. The PSX outputs plenty of juice, but its 'only' 40 volts DC, which seems to be a bit restrictive in terms of using it to drive high power class D amplifier modules, most of which seem to like at least 50 to 80 volts. So I wonder if I can canvass some opinions?

Question 1 - could I get 100w plus from a class D amp module running on 40 volts DC? What would you recommend? It doesn't have to be a class D amp: do you have any recommendations for high power class A/B amps that could work off the PSX supply and maybe give at least 200/250w?

Question 2 - my initial investigations seem to reveal that i'll be struggling to find a DIY amplifier module that'll do much more than 100 watts or so with 40 volts DC, in which case, I may as well use the original Cyrus 2 amplifier. With a PSX this should provide approx 90 watts or so into 4 ohms...but is it an ideal choice for a subwoofer amp? I suspect not, but I could be wrong?! The quality will be lovely, but those output devices are quite small and i'm not sure it will be that robust. I wonder if some extra cooling aids would give some extra insurance? Then again, in all honesty, i'm not after huge sound intensities but for something that's going to be working from 50Hz or so downwards it'll be working hard regardless.

Question 3 - could I upgrade the PSX? I could fit another 500va transformer with higher voltage secondaries...but then i guess i'd have to increase the voltage across the PSU board including those expensive slit foil PSU capacitors. Sounds expensive...but could something be done I wonder?

Answers on a postcard :)
It depends on the impedance of your bass driver.
If you stick to 4 ohms, then a realistic 150w RMS @ +-40vDC could be achieved from a Hypex UCD 180, although I would go for the NC400 as it has 25 Amp current capability compare to 10 amps for the UCD180.
However, there is the possibility the PSX could be getting quite old and the reservoir caps may require replacement.

The Cyrus 2 can supply lots of current for bass duties, +- 60 Amps, but will run out of puff at high volumes, due to voltage limiting as its not as efficient as Class D.
You will only get about 80 watts from the Cyrus into 4 ohms.

A more cost effective solution may be to purchase something like a Hypex Plate amp, which has PSU and Bass filtering in place.
Cyrus will be very happy to drive low frequency signal ...The band width and speed of this amplifier actually can only support this

But from stability issues IE quiet a lot of power , constant duty , demanding load , stability versus temperature , ability of the beer can amplifier to dissipate heat and a few other voltage issues you are simply D R E A M I N G !!!!! ....

Happy transistor replacement
Sakis !
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.