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Re: Gonna Try Building a 1kW Class D Amp for Only $396
SRoode #335307 01/22/11 01:54 PM
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As a test, I directed my HEPA filter fan at the stock heatsinks. I was able to turn the receiver up to +7db with no cut outs and the amps stayed at about 78F. I was only able to hit about -3db on the receiver before. This volume was painfully loud, so I had to take pictures quickly and get out of the room. So, it's definitely something that can be fixed with better cooling.





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Re: Gonna Try Building a 1kW Class D Amp for Only $396
SRoode #335319 01/22/11 04:07 PM
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That's quite a difference. Good to hear, Steve.


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Re: Gonna Try Building a 1kW Class D Amp for Only $396
Adrian #335346 01/22/11 06:38 PM
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Only here (and a few other sites) would someone understand the need* to improve an amplifier so that it can play comfortably and reliably at a level which forces you to leave the room wink

* I originally said "desire" but "need" is probably more accurate


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Re: Gonna Try Building a 1kW Class D Amp for Only $396
bridgman #335355 01/22/11 10:36 PM
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That right!

Quick question. Since I'm probably going to leave the amp unbridged, the idea popped into my head to bi-amp the M80s just to see what it sounds like.

If I remove the jumpers on the binding posts, is each pair of posts a 4 ohm load, or are they now an 8 ohm load? My guess would be 8 ohm since the jumpers acted to put the loads in parallel.


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Re: Gonna Try Building a 1kW Class D Amp for Only $396
SRoode #335356 01/22/11 10:36 PM
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No, don't think so. Someone explained this awhile back, and they remain 4 ohm.


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Re: Gonna Try Building a 1kW Class D Amp for Only $396
Ken.C #335357 01/22/11 10:51 PM
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They're reactive loads due to having the crossover involved, as you get into the "cut" range of the filter it starts to act like an open circuit. So the two halves of the speaker are not in parallel.


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Re: Gonna Try Building a 1kW Class D Amp for Only $396
ClubNeon #335359 01/22/11 11:00 PM
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Yep. The two halves of the speaker present their 4 ohm load at different frequency ranges, and have a higher impedence outside of their active ranges.

The problem is that without an electronic crossover you're sending all of the frequencies to both amps anyways, so you wouldn't get the benefits of a "real" bi-amp system that sends different frequency ranges to each amplifier.


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Re: Gonna Try Building a 1kW Class D Amp for Only $396
bridgman #335360 01/22/11 11:18 PM
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But you do get the advantage of full voltage power to each side, rather than having that voltage split between the upper and lower sections, not sure if that makes alot of difference to SQ, might make it even a little tighter in the bass region.


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Re: Gonna Try Building a 1kW Class D Amp for Only $396
bridgman #335361 01/22/11 11:26 PM
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True, (and I know this was discussed many times on this board years back), but since each "half" of the speaker is only really reproducing it's frequency range and not reproducing the frequencies outside of it's range, the speaker is actually drawing less power from each amp stage at any given setting on the receiver when I bi-amp right?

What I mean is, lets say I have the receiver at -12db. The high part of the speaker is dissipating, let's say 10W, and the low part of the speaker is dissipating, let's say 10W also. That means the single amp is "delivering" 20W.

If I leave the receiver setting at -12b, and change to bi-amp, both low and high still dissipate 10W, but now each amp is only "delivering" 10W.

In the end, if I had my sound meter measuring before and after, the sound level should be the same, right? And, I gained headroom on each amp.

Am I missing something?


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Re: Gonna Try Building a 1kW Class D Amp for Only $396
SRoode #335362 01/22/11 11:34 PM
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I think if tweeters dissipate 10W, I think they melt.


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