[cdyckes]

I've decided to add a better power amp stage to my Denon 4306/Gallo AV Reference speaker 7.1 setup and get a bit more power reserve at the same time.

As I'm quite good with a soldering iron (I'm a graduate EE), I've looked at the ClassD modules by Hypex and ColdAmp.

I know the Hypex ones are used in the CI Audio D-200 which gets rave reviews, but I've also read that the ColdAmp BP4078 400W modules have a warmer fuller sound which is definitely what I'm after for exclusively 7.1 useage, even for music (PLIIX Cinema mode for everything).

I'm about to hit the 'buy' button on two of these kits:-

http://www.coldamp.com/opencms/openc.../pack_hifi_mch

to make up an 8 x 230W (into 8 ohms) power amp using switch-mode psu's and the case of my old Technics SE-A50 (sacrilege maybe, but technology moves on ).

Anyone think I'm making a mistake and should go for the Hypex instead???

Colin

[garyb9900]

Dunno about choice of kit but are you sure you want to run everything through it in PLX II?

[pcavelle]

Hello Colin - my only comments, apart from your slightly dubious choice of case - is that the Hypex are very well established and are now being used in the Meridian reciever that has just been announced. Also - they look a bit neater all round than the ColdAmps. and are possibly cheaper too.

Have you seen the Dutch company, can't remember the name, that are doing very nice kits based on Hypex modules, in good looking aluminium cases. I will try & look them up for you.

Have you looked on DIY Audio forum? They're pretty biased towards Hypex there but there are some very knowledgeable people there who can advise.

Finally - don't know whether you are interested in IcePower fromn B&O? The modules are very difficult to get hold of but if you search for 'IcePower' on audiogon.com, you will find some 'box stuffers' like Magnum, who are producing inexpensive multi channel IcePower based home cinema amps.

Cheers, Paul

[cdyckes]

Paul,

Thanks for that info. The Hypex with the better input op-amp are about 30% more expensive, but that's not really a relevant factor as the total projected cost for 8x230W into 8Ohm using the ColdAmp with 2xSMPSU's is sub £1000 allowing £150 for connectors - can't be bad! This time, buying European means we don't get ripped off by 'distributors', especially as the manufacturer sells direct

I'd found a couple of threads elsewhere that compared the two and other peoples comments on the 'warmth' of the ColdAmp attracted me. Made a mockup of 8 amp modules and two PSU's and they fit the case with room to spare (as would 8 x Hypex).

I'll check out the links you gave me.

p.s. I LIKE the case

[pcavelle]

Please let me know how you get on with this Colin, I've been itching to try out a three channel version (Hypex) for a couple of years but the Coldamp may be a better bet from what you're saying.

Thanks & regards, Paul

[cdyckes]

Ordered the Coldamp gear today. Hopefully get the bits late this week/early next!!

Not sure whether to bother with volume control on the power amp. If I do, it'll probably be by digital pots controlled by the two buttons I have on the front panel (probably make a quick PIC micro board and use I2C pots). The Coldamp units have a volume control capability after the initial input stage so this should work well. Will also add 12v switching.

I'll let you know how I get on and post some pics (if FileXoom ever sort out my account again)

[cdyckes]

Paid the PayPal invoice from ColdAmp on Monday (not a bank holiday in Spain). They had told me that they had ths SPS80's in stock but were expecting BP4078's on Tuesday/Wednesday. They shipped my order on Wednesday and I received it in the UK on Thursday (today)!

Two pics of probable layout:-

Old speaker connector blocks will be replaced by ones with 4 speakers on each side giving a 'dual-quad' amplifier. Input phonos will be at top centre rear of case and screened. Input routing for each quad amp. are together and away from speaker outputs and mains.

Just need to see if I need fan cooling. If so will add two 120mm slow speed computer fans in case lid controlled by thermistors in BP4078's.

They were so quick delivering, I haven't even got the connectors yet, so will do a quick stereo lash-up to test the principle and maybe try an A/B test.

Will only post any results I get for interest, as if I post any more construction details I'll probably get moved to the DIY thread where no-one will see them

Colin

[pcavelle]

any progress Colin? Got it all working now?

Paul

[cdyckes]

Paul,

I've got it all working in 'breadboard mode' driving 4 channels at at time via the old speaker terminals. Checked both sets of 4 amps and all work. Have a minor switcher sound breakthrough on one amp nearest to the LH switcher. I only need 7 and was going to use one as a 'cold backup' so probably not an issue, but may try some shielding. All the others work perfectly.

Haven't got it fully finished and any form of comparison testing done yet as I'm relearning my CNC program for my mini-mill to make the terminal plates for the back-panel (I want them to be perfect). Hopefully not long now.

Initial inpressions are VERY good.

[cdyckes]

Finished and working and sounding VERY good.

Still can't answer the question I posed in the thread title, but I can say they make mincemeat of the Denon 4306 power stage!

Fans just rest on top of amp modules and are NTC controlled via thermistor in coldamp modules and speed control circuit in sps80 SMPSU. Cooling is via three rows of holes alongside the amp modules (6.5mm diameter on 20mm centres) and two speed controlled fans.

with fans lifted out of the way.

originals in my gallery at
http://www.pbase.com/cdyckes/misc&page=all

Total cost was about £1200 all-up including all connectors (but excluding case which I had).

[JohnWH]

Have you considered bolting the amp modules onto a couple of rows of vertically mounted heat sinks so that you can dump the fans? Or do they tend not to kick in very often?

Impressive how much punch can be packed into a small box though...

John.

[cdyckes]

John,

Yes I did consider that, and it would almost certainly have been enough to dispense with the the fans.

The fans run constantly, but are speed controlled by the NTC sensor/speed controller in the SPS80's circuit. The fans themselves are only supposedly 21dbA at full speed (though I doubt this is true), but they're totally inaudible more than half a metre or so away (and make less noise than the PF9 fans).

I know fans are frowned on, but I thought they'd help long term reliablility by keeping temperatures down (My Denon 4306 ran far warmer than I liked).

[pcavelle]

very very impressive!

[Resonance]

I just came across this thread. Very impressive Colin.

After living with the ColdAmp modules for 6 months how would you rate the sound? Would you go for the same ones again?

I am looking for a good 2 channel power amp (maybe 4-channel if I decide to bi-amp the speakers) and this looks as though it could be a good low cost route.

Ian.

[cdyckes]

I'm VERY happy with the sound and would go for them again.

I have one minor reservation, in that at extremely loud settings (Pink Floyd 'Comfortably Numb' at VERY high volume), the front side channels occasionally cut out for a second or so as the protection kicks in. I mentioned this to ColdAmp and they suggested adding the LEDs that show if I'm hitting the voltage rail limits, which I've yet to do.

Obviously this is dependent on speaker impedance curve and sensitivity, but I've noticed a definite lower maximum sustained output with the Gallo Reference AV's and ColdAmp setup as compared to the old Technics 5.1 amp and KEF 104.2 fronts and KEF Reference Theatre centre and dipolar sides.

I'd qualify this by saying that I'm no audiophile, and basically use the system with the Panasonic 65" PF9 as an expensive TV/DVD player