Suggestions for power amp build

[Spirit]

Hi guys,

I'm looking to build a power amp to drive some Dali Ikon 7s - 8ohm, measured 89dB (specced at 92), recommended power 25-200W.

Will use the buffalo as source, volumite as volume control (which incidentally doesn't go to silence at minimum).

I've been eyeing off the ULD Extreme www.diyaudio.com/forums/solid-state/142166-new-amplifier-uld-extreme.html
- Douglas Self's "Blameless" design, more or less. 170W or so into 8ohms.

Jeff also suggested I look at the Pass F5 - far better documented to be certain, class A or AB depending on output. Power tops out at 25W.

In the room I have them in now, I probably wouldn't use more than about 3W (if the display on my current receiver is to be believed).

After about 2W, distortion on the F5 does rise fairly rapidly.

Any thoughts/suggestions etc?

Cheers,
Phil

[Deleted]

I've been eyeing off the ULD Extreme www.diyaudio.com/forums/solid-state/142166-new-amplifier-uld-extreme.html- Douglas Self's "Blameless" design, more or less. 170W or so into 8ohms.

Phil
Have you checked out the Jaycar modules that the thread was based around ? Like all of these recent projects, the case metalwork is the hard part. The cost of bringing fancy power amplifier cases into Australia is prohibitive for most. You could also PM Alfred (Alchemy) or Allan Pagan for further advice in this area. Altronics also have the complete kits for the 20W Class A and the earlier SC ULD. Fairly expensive though.
Alex

P.S.
My front end balancing mod is VERY easily fitted to this one, as Alfred can attest.
www.jaycar.com.au/productView.asp?ID=KC5470&CATID=25&form=CAT&SUBCATID=557

[robertkd]

Well my preference would be somewhat more then a few watts, even looking at the speaker specs of 89db spl firstly you normally don't sit 1 metre back from your speakers more like 2 to 3 or more add some room absorption and your down to 80 odd db SPL at listening position.

also factor in that the rating normally refers to single tone a more likely 1Khz, boring to be sure but music normally has a wide spectrum density simultaneously plus added dynamics before you know it your running 10db or more peak power then your original 1 or so watts that you might have expected.

Also consider compression, no not in the production of the material but the compression that comes from "speakers" just because manufacturer says peak power is x doesn't mean this will be a certain db louder then at 1w, simple fact most domestic speakers run out of go somewhere between 100 to 110db SPL

So for an average listening level of say 85db spl and that's pretty loud with good dynamic range without compromising the amp I'd go for the ULD or similar 100 to 150W whilst I don't expect to use all of it the dynamics will be good and less distortion artefacts on peak transients.

The low power stuff will give similar if you can get your speaker up to around 98db spl or better.

my thoughts anyway

<typo>

[Spirit]

Alex,

I had seen them. I understood that the ULDE was an improvement?


Cheers,
Phil

[Spirit]

Cheers Robert
I was leaning towards it for those reasons, but without any of the knowledge to back it up

[Spirit]

P.S. Alex - the cost doesn't worry me all *that* much... just means the project finishing date gets put back a month or two

Having said that, I have a bit of choosing to do - there are a cr*pload of things I'd like to buy/do over the next 18 months.

Shortlist:
Radeon 5850 / custom cooling (video card)
Power amp
Possible trip to UK in October to see/hear Jean Michel Jarre (depends entirely on uni)
Replace woofers in Mach Three's
2-3 month trip to India at end of 2011
Android-based phone

Yeah.

[XTRProf]

May 6, 2010 10:08:36 GMT Spirit said:

Jeff also suggested I look at the Pass F5 - far better documented to be certain, class A or AB depending on output. Power tops out at 25W.

Phil, the F5 is designed more for high efficiency fullrange speakers. The F2 sounded beautiful when driving the Coral fullranger based on what I heard more than 2.5 years ago. Fyi.

[Deleted]

I've been pondering the possibility of a DIY power amp for a while now.
The ULD looks attractive, in Jaycar short form but leaves loads of questions!

I assume that;
Jaycar KC5471 PSU
...........KC5470 AMP
...........MT2140 TRANSFORMER
...........MT2086 TRANSFORMER
would take care of the basics. Plus an appropriate case and all panel mount hardware.

Initial Qs;
Would I need to add a speaker protection board?
What size heatsink?
Do the transistors need to be insulated from the 'sink?
Any essentials I've missed?

I started reading through www.diyaudio.com/forums/solid-state/142166-new-amplifier-uld-extreme.html but drowned somewhere between page 3 and 4

All advice-for-idiots greatfully received