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Three very different amps. Which to choose?

DanielT

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The Fosi amp has more power at higher phase angles

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That's how it is. For that price you can't get the best "high end" but you get a damn good amp for the money.:)
 

Doodski

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The Fosi amp has more power at higher phase angles

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Do you know the test methodology for the 4 Ohm and 2 Ohms tests? Is it a blip/short burst of a signal for a short duration etc? If so what is the duration?
 

SIY

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That's not correct, Purifi vs AHB2: Link
I was wondering how long it would take you to get back to your obsession.

O/P: This is stuff best ignored.
 

Doodski

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That's how it is. For that price you can't get the best "high end" but you get a damn good amp for the money.:)
I am veryyy impressed at the Fosi. I can't say enough good things but I am holding reservation until I see how it performs with heat and the longer duration transients that cause the thermal overload to possibly be affected.
 

FWLarson

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Would it sway your opinion if I could get the pass labs 250.8 amp used for $6700 usd in good condition?
On the basis of performance and sound, we chose the X250.8. Excellent, remarkable control at all power levels (our speakers are 4ohm, 87db efficiency, smaller room with unoptimized acoustics).
 

Beershaun

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Come on guys, please understand, the woofers of the F208 have a combined rated power handling of 120W per speaker. If an amp can deliver this power without too much distortion, the sound doesn't improve if more amp power is available. But even with 120W (or less) from the amp, this speaker would distort and compress significantly I guess.
You didn't bother to watch the video I posted did you?
 

Beershaun

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Because some amps are false specced?
More amp power usually don't hurts if not pushed to the speakers, just makes your wallet lighter.
I would be curious what this speaker would do if 350 real, low frequency Watts would come from the amp.
What amps are false spec"d? Almost none that Amir has rated. How are speakers power spec'd?
 

Beershaun

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Yes I watched it before and now again. As I remembered, this "demonstration" can easily be fake, especially on a video.
Omg stop. You have been promoted to my ignore list.
 

YSDR

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I think active speakers is good examples of amp to speaker matching. A close thing to an F208 is an ATC SCM45A Pro for example (yes I know that ATC claims two 164mm woofers but they are clearly 8" woofers in the traditional view of drivers) and they put a single 150W amp for the woofers. They could have done it with their 2x275W amplifier pack, but they didn't because probably it would be a waste.
Anyway, as I said, more Watts don't hurt the speakers if not delivered to the speakers. If someone want a thousand W amp, then buy and use it, it's his money and decision.
 

Willem

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To go back to the original question: of these three amplifiers I would only ever consider the Purifi one. However, if what the OP wants is impactful clean bass, it would still not make a huge difference. For that, he needs to reconsider the framework of the problem. For clean and forcefull bass he needs multiple subwoofers, properly equalized (they do not need to be very large). Those will add power where it is needed, and extension. I don't know if the current amplifier allows or has a high pass filter, but that would make the multisub route even more successful as it relieves the power amp and main speakers of the heavy lifting of lower frequencies. Of course, such subs would need proper dsp room equalization, and I would suggest Muti Sub Optimizer, as that equalizes across a wider listening space.
 

Blumlein 88

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I think active speakers is good examples of amp to speaker matching. A close thing to an F208 is an ATC SCM45A Pro for example (yes I know that ATC claims two 164mm woofers but they are clearly 8" woofers in the traditional view of drivers) and they put a single 150W amp for the woofers. They could have done it with their 2x275W amplifier pack, but they didn't because probably it would be a waste.
Anyway, as I said, more Watts don't hurt the speakers if not delivered to the speakers. If someone want a thousand W amp, then buy and use it, it's his money and decision.
None of the three amps were 1000 watts. The Apollon was what 375 watts. That is not quite 5 db more than 120 watts..
 
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Willem

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I dont have room for a sub bigger that 12" on th left.

So, do I get one larger sub on the right 15-18" or two 12" subs?
Multiple smaller subs are always better. Multiple subs make for a smoother response, and potentially also across a larger listening space. Two is the minimum, but three or four is usually even better. Also, they don't have to be identical. Earl Geddes argues that one pretty big sub is enough to get really low, while the others can be smaller serving to smoothen the response. That is what I did in an almost similarly sized room (one SVS SB2000 in a front corner, a 2x8 inch B&W PV1d in the back, and a Kef Kube 8b on the side. I am currently pondering where to place a fourth sub). Such large rooms really ask for largisch subwoofers. Multi Sub Optimizer software is the best way to equalize multiple subs because it equalizes them independently for best results across a large listening area. Unfortunately it is pretty hard work.
 

Gorgonzola

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Hi,

I have done a good bit of research over the past 6 weeks - on-line reviews, forums, YouTube videos, etc. Opinions are all over the place and I am having a hard time deciding on a new amp to power Revel F208 speakers, with possible future speaker upgrade. (large room 20x30 20' ceilings). I have gotten a lot of great advice and gained knowledge during the process, however, some of it is conflicting.

I've managed to narrow it down to three amps and I'm going to throw it out there to hopefully recieve your direct comparative feedback and insight.

Which do you like and why? They are all highly respected and reviewed, but differ in approach to audio fidelity.

I've got a serious case of analysis paralysis ;), but expect to pull the trigger within a couple weeks. I hoping for a keeper for the next 15-20 years.

Pass Labs X250.8

Quicksilver KT Mono

Apollon PET1200

There could scarcely be three more different amplifiers: all of them over priced IMHO.

But briefly, I've owned Pass and I've owned Purifi and I personally would go for Purifi every time ... but not Apollon's "Premium" products, (being both a tightwad and poor).

If you're willing consider a Quicksilver KT, then a lower powered Purifi should work very well for you. If you prefer a mono, I'm I consider a Purifi 1ET7040SA model, e.g. Buckeye's PURIFI 1ET7040SA Monoblock, v2 for a lot less money.
 

YSDR

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None of the three amps were 1000 watts. The Apollon was what 375 watts. That is not quite 5 db more than 120 watts..
Of course that was just an exaggeration from me. 5dB don't seems too much difference with a layman's eye but the excursion of the woofer(s) is almost 4x for that 5dB, which means the voice coil can easily hit the pole piece or jump out of the gap and suffering permanent damage. Or simply burns down from the electrical power.
 
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Blumlein 88

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Of course that was just an exaggeration from me. 5dB don't seems too much difference with a layman's eye but the excursion of the woofer(s) is almost 4x for that 5dB, which means the voice coil can easily hit the pole piece or jump out of the gap and suffering permanent damage. Or simply burns down from the electrical power.
It won't burn down from the power unless you run it max power for a few seconds. Which isn't happening with music. I'm pretty sure 5 db won't hit the pole piece, but I need more specifics on that I suppose. Revel suggested amps up to 350 watts. Such ratings are drawn with a fat crayon not a sharp mechanical pencil. I'm not advocating super high power or that you get benefits from excess power only that moderate extra power is unlikely a problem or danger to the speaker.
 

Willem

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Big power is mostly required for short dynamic peaks in, for example, the symphonic repertoire. Such short peaks normally do not destroy speakers. What does is high levels of continuous power, such as in pop music that is mastered with limited dynamic range, or clipping of underpowered amplifiers.
 
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