High Power Chip Amp

[Mark Allen]

Load it at 1 ohm and let me know if it works ..........

Well, the Class D board won't work at 1 ohm so whats your point? I suppose we could parallel in a couple of more 3886 chips and it probably could do 1 ohm.

Star... Considering this is Class AB I'm actually very surprised at how cool the chip amp stays for the amount of power it can put out. Of course this is three chips paralleled not just one. At idle it barely gets warmer than the T.I. board does. I've never had any issues running hot class A amplifiers here during summer... Most houses here use evaporative cooling in the summer!!

So now I have Krell Clone(KSA50 & KSA-100), 3- Pass Clones, BPA-300 Chip amp, and T.I. based Class D board all here in one room... so it's time to invite the listening panel over...

Mark

[Samuel Jayaraj]

I saw that the 3 Pass clones you have built are Pass Aleph 2's, Aleph 30, Aleph Mini. The Alephs do have their signature sound - some like it, some don't. I guess the X-version might help in removing some of that haze you notice! Then there is the FirstWatt series which do not exhibit the Aleph Current Source, except for the AlephJ.

[AndrewT]

the easy solution to arguing over 2ohm or 1ohm speakers is to ban the manufacture of 1ohm and 2ohm drivers/speakers.
Even 4ohm is unnecessary. We can all manage with 8ohm, even for the professionals into high SPL PA equipment.

Now, if we accept that 8ohm is the standard driver impedance then we need the chipamp manufacturers to come clean on the current capability into real 8ohm speakers/crossovers.
A 3886 is limited to >=7Apk when cold. That cannot drive an 8ohm speaker load in real music driving conditions at higher SPLs, if the speaker if less than high sensitivity(>=93dB/W@1m).

The advantage of the parallel chipamp set-ups is the increased current ability.
Chipamps desperately need more current ability into 8ohm speakers. Don't consider using low sensitivity (<=87dB/2.8V@1m) 4ohm speakers.

[star882]

How much did the hybrid cost altogether? What about the analog? At high powers, the hybrid has a significant cost advantage, although it might be obscured somewhat by artificial price premiums.

the easy solution to arguing over 2ohm or 1ohm speakers is to ban the manufacture of 1ohm and 2ohm drivers/speakers.
Even 4ohm is unnecessary. We can all manage with 8ohm, even for the professionals into high SPL PA equipment.

I have no idea why they even make speakers with an impedance so low. The stray resistance losses are just too significant. Maybe if there are several sets of speakers to be driven from the same source, which can then be simply connected in series. But series/parallel with 8 ohms works as well.

[a.wayne]

Originally Posted by AndrewT

the easy solution to arguing over 2ohm or 1ohm speakers is to ban the manufacture of 1ohm and 2ohm drivers/speakers.
Even 4ohm is unnecessary. We can all manage with 8ohm, even for the professionals into high SPL PA equipment.

Now, if we accept that 8ohm is the standard driver impedance then we need the chipamp manufacturers to come clean on the current capability into real 8ohm speakers/crossovers.
A 3886 is limited to >=7Apk when cold. That cannot drive an 8ohm speaker load in real music driving conditions at higher SPLs, if the speaker if less than high sensitivity(>=93dB/W@1m).

The advantage of the parallel chipamp set-ups is the increased current ability.
Chipamps desperately need more current ability into 8ohm speakers. Don't consider using low sensitivity (<=87dB/2.8V@1m) 4ohm speakers.

Originally Posted by star882

How much did the hybrid cost altogether? What about the analog? At high powers, the hybrid has a significant cost advantage, although it might be obscured somewhat by artificial price premiums.

I have no idea why they even make speakers with an impedance so low. The stray resistance losses are just too significant. Maybe if there are several sets of speakers to be driven from the same source, which can then be simply connected in series. But series/parallel with 8 ohms works as well.

Yes I guess we should all get un-listenable dinky toy speakers so our likkle chip-amps can drive them .....

[Mark Allen]

I've actually built 4 Alephs. Mini, Aleph 3 for a friend, Aleph 30, Aleph 2's... also Both Krell Klones.

the easy solution to arguing over 2ohm or 1ohm speakers is to ban the manufacture of 1ohm and 2ohm drivers/speakers.
Even 4ohm is unnecessary. We can all manage with 8ohm, even for the professionals into high SPL PA equipment.

Andrew... I think that statement is a little off the wall my friend! Well there are the Apogee ribbon speakers that dip down to 1 ohm... and they are stunning speakers... thats what brought the KSA-100 into existance. In movie theaters we don't like to series-parallel speakers. You have more phase related problems from doing this than load problems from paralleling them. So we usually parallel them in groups that get us to two ohms and this usually means 4 speakers on a channel of a given amp. Many commercial amps are available that will safely drive 2 ohms today. I usually use QSC. I do however consider the Class D board to be high quality to the point that it could be used in Cinemas so I am looking into doing that. I have a myraid of places I can install and test them under all sorts of different conditions.


Star... The LM3886 based amp cost about the same to build as the Class D board and large switching power supply cost to buy. I had a pair of old AB Systems power amps that I stripped out and used the chassis for the chip amps. The Class D board still sits on top of one of the Dynaudios. FYI: If you want to the same chip amp on the cheap you can buy the same chip amp board assembled from China for $40 USD but they do them with through hole parts. I got mine from Per Anders and also bought the SMT parts from him at the same time in that last group buy. The boards and parts were about $110 USD for four boards and sets of parts.

Mark

[star882]

Maybe compare them to a pure digital, then. (You'll obviously need a digital source or it will lose every time.) In theory, pure digital is the very best, even better than hybrid. In practice, I like the smug factor of the hybrid, not to mention that most pure digitals need a microcontroller to start them up.

[AndrewT]

Originally Posted by Mark Allen

Andrew... I think that statement is a little off the wall my friend!
.............................So we usually parallel them in groups that get us to two ohms and this usually means 4 speakers on a channel of a given amp. Many commercial amps are available that will safely drive 2 ohms today.

why put four 8ohm drivers in parallel and then drive them with a 2ohm capable amplifier? It makes no sense other than economy.
A four amplifier system driving four individual 8ohm drivers will be far more resilient if any component fails during a performance. This applies especially to PA, where the sound MUST GO ON.

Mark,
your reasoning may go a long way to explaining why most PA systems, whether disco, or cinema, or live concert (indoor and outdoor) sound pretty near dreadful.

[a.wayne]

Apples and oranges Andrew ,


The discussion was regarding series vs parallel speakers not one amp vs 4.

[AndrewT]

no, the discussion became 1ohm and 2ohm loading.
Avoid at all cost and limit to no lower than 4ohm if and only if one is forced down that route.
Stay with 8ohm, or higher, if the budget allows.