PC Hi-Fi: Scythe's Kama Bay Amp

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Devonavar
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PC Hi-Fi: Scythe's Kama Bay Amp

Post by Devonavar » Mon Mar 24, 2008 11:49 pm


floffe
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Post by floffe » Tue Mar 25, 2008 2:49 am

It might be worth buying just to drive the neighbors crazy when their phone drops out...
:lol:

I wasn't aware this kind of amp was available, seems pretty neat. Sounds like a decent enough thing for my possible future needs (i.e. moving to an apartment with more than one tiny room), as an alternative to a used, regular amp.[/quote]

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Post by zoob » Tue Mar 25, 2008 3:03 am

Neat product. I've been toying with the idea of building a Pimeta into a drive bay as well but haven't gotten around to it :D

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Post by HammerSandwich » Tue Mar 25, 2008 5:20 am

Now we need a Sonic Impact review for comparison.

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Post by Avalanche » Tue Mar 25, 2008 5:36 am

t might be worth buying just to drive the neighbors crazy when their phone drops out...
I apologize for not doing any research, but aren't there laws against products that cause RF interference?

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Post by BillTodd » Tue Mar 25, 2008 6:36 am

Avalanche wrote:
t might be worth buying just to drive the neighbors crazy when their phone drops out...
I apologize for not doing any research, but aren't there laws against products that cause RF interference?
Older switch mode amps were notorious for interference and poor distortion etc. but, thanks to much higher frequency switching devices (that make filtering the output easier) the new devices don't produce RF interference and perform as well as most (and better than many) analogue amps.

Have a look at these Hypex modules (http://www.hypex.nl/)

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Post by aburgard » Tue Mar 25, 2008 9:08 am

I have to say that I love my Sonic Impact Super T-Amp and have many times considered mounting it inside the PC.

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Post by jessekopelman » Tue Mar 25, 2008 9:09 am

I'm surprised you didn't mention power draw in the review. The reason I bring this up is that my receiver has a very high idle draw -- 50W. What's funny is that playing music at decent volume only increases the draw by about 10W. With only 15W output, I'm sure the Scythe can't have much of a draw, but I'd be curious to see if it idled close to 0, like one might expect or if the idle draw is actually pretty close to full load (as I'm suspicious it is).

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Post by MikeC » Tue Mar 25, 2008 9:15 am

BillTodd wrote:Have a look at these Hypex modules (http://www.hypex.nl/)
Great link, they look like great products.... Not sure I should thank you tho: I'm beginning to feel the need to build a multichannel amp... :roll:

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Post by matt_garman » Tue Mar 25, 2008 9:38 am

HammerSandwich wrote:Now we need a Sonic Impact review for comparison.
aburgard wrote:I have to say that I love my Sonic Impact Super T-Amp and have many times considered mounting it inside the PC.
Russ Kinder wrote:I think the real competitor to this is something like the Sonic Impact T-amp... The Sonic T sounds amazingly good. I've been using one for a couple of years now in my workshop system, and it consistently impresses people. Jeff Day did a nice write-up of it over at 6moons a while back.
There's another Sonic Impact T-Amp review here.

To those of you who own the Sonic Impact T-Amp, what speakers are you using with it?

I've come to the conclusion that unless you spend a fortune or build your own, generally these low-powered amps will have weak bass without horn-type enclosures for your drivers, or you get the bass but weak overall volume. See the thread I started over on DIY Audio Forums.

Anyway, regarding the interference issues with the Kama Bay Amp's power supply: try using a car battery to power the amp. There are a fair number of people powering their Sonic Impact T-Amps with car batteries. In fact, the Super version of the SI T-Amp comes with a power cord designed specifically to connect to the terminal posts of a car battery.

Of course having a big car battery sitting next to your computer kind of kills the tidy effect of having your amp integrated into the computer case!

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Post by autoboy » Tue Mar 25, 2008 9:46 am

I want to add that you CAN use a subwoofer with this amp. If your sub has line level inputs (they look like regular speaker terminals) then you can run the cables through the sub and the sub's crossover will pull the bass out of the signal and pass the rest on to your speakers. I don't think this is much of a real product. 10W is so little power that it can't really handle bass and the interference is not a good thing. Sure, most speakers operate at only 1W at normal listening volumes, but the spikes for bass require much more than that and an amp with only 10W can't really cut it.

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Post by BillTodd » Tue Mar 25, 2008 9:48 am

MikeC wrote:
BillTodd wrote:Have a look at these Hypex modules (http://www.hypex.nl/)
Great link, they look like great products.... Not sure I should thank you tho: I'm beginning to feel the need to build a multichannel amp... :roll:
I've used them in a couple of pro-audio projects (and have a couple of others in the pipeline), including a 200w/ch amp in a 1U box using SMPSUs which has received praise from all who've heard it.

Recommended.

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Post by derekva » Tue Mar 25, 2008 10:30 am

matt_garman wrote: To those of you who own the Sonic Impact T-Amp, what speakers are you using with it?
I've got one in my garage driving a pair of 1989-vintage Paradigm 3se Mini speakers and being driven by my old Lazarus Cascade Basic preamp, a Kyocera 410dx CD player and a Luxman 410 FM tuner. The speakers are mounted high up on the walls near the ceiling, so there is a decent amount of bass loading (especially given that the 3se Mini is a rear-port reflex design). Fairly musical and plenty loud when I'm working on my car or at my workbench, but not as good as my tube rig inside. :D

I've also tried it on a pair of Axiom M22ti's and a pair of open-baffle Fostex FE103s - all worked well, but they are all fairly sensitive drivers with friendly loads.

The Sonic Impact will work well with any speakers over ~ 95dB/1W/m, so you don't just need horns (although the HornShoppe horn is a decent match).

-D

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Post by kittle » Tue Mar 25, 2008 12:17 pm

I found the best investment was a 25 foot cable with a mini jack on one end and a RCA connecter on the other.
Buy several (or build your own) and you can easily hook your PC soundcard output into your existing home theater setup.
Or if your adventurous, get an optical cable and hook that into the optical output of your soundcard (my card doesnt have one), and then the optical input of your receiver.

One question on the review:
Most amps list a frequency response range. The norm being 20hz to 20000hz Was that stat left out of the review? or does the karma bay amp not publish one?


Derekva has a good thought though. with only 10w output, this amp would be great for a horn setup. Although that goes totally against the idea of using it in small spaces.

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Post by Aris » Tue Mar 25, 2008 12:29 pm

Im having a real hard time trying to figure out who would buy it.

No subwoofer support leaves out A LOT of people. Even my mom who only sufs the net and checks her email, and occasionally downloads something on iTunes has a 2.1 speaker system that has a subwoofer.

Lack of 4 or more speakers isnt that big of a deal. Most people just use 2.1, or headphones if they want a more "surround" sound.

So then your really only left with people who want to listen to music from their computers, (styles light on bass, so not rap etc), and care enough about sound quality to want better than something from creative labs. But i would think if you were one of these people, why wouldnt you just get a GOOD amplifier and just sit it next to your computer? Theres really no reason to make it fit inside the computer.

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Post by Devonavar » Tue Mar 25, 2008 3:31 pm

I'd love to snag a T-Amp sample (and keep it), but I'm not getting my hopes up. Trimark, the company that made the chip inside went belly up about a year ago.
I apologize for not doing any research, but aren't there laws against products that cause RF interference?
Yes. Clearly, Scythe could get themselves into trouble here...
I'm surprised you didn't mention power draw in the review. The reason I bring this up is that my receiver has a very high idle draw -- 50W. What's funny is that playing music at decent volume only increases the draw by about 10W. With only 15W output, I'm sure the Scythe can't have much of a draw, but I'd be curious to see if it idled close to 0, like one might expect or if the idle draw is actually pretty close to full load (as I'm suspicious it is).
I'm afraid I didn't do this, but I can tell you that the brick is rated for 3A at 12V. Some other power tidbits: Scythe cites 88% efficiency and 10W per channel, which works out to ~23W with both channels going full tilt. I think the fact that the interference gets noticeably worse when the volume is turned up suggests that the power draw also increases significantly.
Anyway, regarding the interference issues with the Kama Bay Amp's power supply: try using a car battery to power the amp.
I wouldn't expect this to solve the problem. Remember, the interference was present even when the Kama Bay Amp was powered from the system. The problem is in the unit itself, not the power supply.
Most amps list a frequency response range. The norm being 20hz to 20000hz Was that stat left out of the review? or does the karma bay amp not publish one?
Not published by Scythe, but the datasheet from Yamaha shows a response curve that is almost perfectly flat up to ~20,000 Hz. I'm not really one to trust a spec sheet though. Theoretically, the amp should be pretty good up to about half of its switching frequency.
No subwoofer support leaves out A LOT of people.
Only if you're thinking in terms of regular computer speakers. A pair of good quality bookshelf speakers should sound better without a subwoofer than your average computer speakers with one. Bear in mind that computer subs aren't so much subwoofers as just woofers that are intended to compensate for the poor low end of the tiny satellite speakers that sit on the desk. With proper speakers, you should get decent low end without needing a subwoofer, and you'll have better balance to boot.

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Post by HammerSandwich » Tue Mar 25, 2008 4:37 pm

matt_garman wrote:I've come to the conclusion that unless you spend a fortune or build your own, generally these low-powered amps will have weak bass without horn-type enclosures for your drivers, or you get the bass but weak overall volume.
autoboy wrote:10W is so little power that it can't really handle bass and the interference is not a good thing. Sure, most speakers operate at only 1W at normal listening volumes, but the spikes for bass require much more than that and an amp with only 10W can't really cut it.
I disagree. Speakers with above-average sensitivity play LOUD on a couple watts, and most people don't need their stereos to pin them against the rear wall. FWIW, I've never noticed any problems with my 30W Pass amp's bass after upgrading from a 200W Adcom. As always, quality > quantity.

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Post by subsonik » Wed Mar 26, 2008 8:55 am

With the amp sharing the same power supply as the rest of the system, every drive seek, every mouse click, and every spin of the scroll wheel was amplified audibly as the electrical effect of each action propagated through the system. Using a power supply with lower ripple and better voltage regulation might have helped, but we're hard pressed to recommend the Molex adapter to anyone who wants clean audio.
Actually, this is not an issue of the power supply. Even with an ideal power supply (zero ripple, perfect regulation), you would still hear the clicks and pops. No, it's a serious design flaw in the amplifier!

The root cause for these issues is a ground loop: the "power ground" on the molex and the "signal ground" on the cinch inputs are tied together internally in the amp. Unfortunately, both grounds don't have the same electric potential: components in the PC drawing current cause voltage drops over the power supply cables. These voltage drops become visible on the amplifier's inputs, and get... amplified.

The solution is rather simple, with a component cost of about a dollar. But as they already threw decent output filtering out, they probably didn't bother to fix this, either.

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Post by matt_garman » Wed Mar 26, 2008 9:13 am

HammerSandwich wrote:I disagree. Speakers with above-average sensitivity play LOUD on a couple watts, and most people don't need their stereos to pin them against the rear wall. FWIW, I've never noticed any problems with my 30W Pass amp's bass after upgrading from a 200W Adcom. As always, quality > quantity.
Would such speakers have adequate bass?

I do agree you can get loud with high-efficiency speakers and low amplification.

But I haven't been able to find any info on high-efficiency speakers that have adequate bass at such levels. Except for horns, anyway.

To be honest, I'm certainly no expert, but have recently been reading a bit about this stuff (see that thread I started on DIY Audio). I don't know about your 30W Pass amp, but the (Pass) F2 mentioned in that thread purportedly has better bass than the Sonic Impact T-Amp at similar wattages... But the F2 either costs about $2k, or you build it yourself.

After I ended up with my not-as-good-as-I-hoped setup of Sonic Impact T-Amp and homemade speakers (based on the Audio Nirvana fullrange drivers), I spent a considerable amount of time searching the web for speakers that were high-efficiency enough to be powered by a tiny amount of power, but also had a decent low frequency range. I couldn't find any that didn't cost a fortune.

But I certainly could have overlooked them.

That's why I asked above what speakers folks are using with their Sonic Impact T-Amps. Ideally, I'd like a pair of bookshelf speakers that are capable of as much bass as any bookshelf, but are high-efficiency enough to be powered by the T-Amp. And, they can't cost a fortune! :)

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Post by MikeC » Wed Mar 26, 2008 9:37 am

matt_garman wrote:deally, I'd like a pair of bookshelf speakers that are capable of as much bass as any bookshelf, but are high-efficiency enough to be powered by the T-Amp. And, they can't cost a fortune! :)
You're asking for small size, great bass extension, high efficiency and low cost. You can probably have any combination of 3 things you ask for. Not all 4. :lol:

Actually the first three alone are very difficult to find at any price except in high-end self-powered speakers that have freq contouring built into the amps. Many speaker designers would suggest that a "universal" amp to power a "universal" passive speaker system is a poor way of going about the task of audio reproduction. They'd say that an iMac type approach, where the amps, the speakers, the box, & the xovers are all integrated into a single unity have a much better chance of being really good.

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Post by sanse » Wed Mar 26, 2008 10:27 am

neat and handy to built in, but the rf-interference is unacceptable.

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Post by MikeC » Wed Mar 26, 2008 10:50 am

The review sample is up for grabs -- $30.

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Post by Jipa » Wed Mar 26, 2008 11:10 am

I'm a bit disapointed you didn't take it apart to see what's inside.... So I searched another review and saw the internals.

It made me lol to see some hype about high quality connectors and see the internals with basic connection wire running from the high quality RCA-connector to the PCB :roll: But it doesn't show, so it doesn't matter?

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Post by niels007 » Wed Mar 26, 2008 1:32 pm

T-amps and the Hypex modules are the SPCR equivalent of quality and power efficient amps that perform superbly.

Only hardcore / prejudiced / audio-idiots remain convinced class D can't work. Those who measure and listened simply said they are SUPERB at amazing efficiency.

This Scythe job might not quite be up those standards though.. :)

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Post by HammerSandwich » Wed Mar 26, 2008 3:18 pm

matt_garman wrote:Would such speakers have adequate bass?
Not automatically, but it's not impossible. For full disclosure, I run a Chaintech AV-710 (really!) into a Melos SHA-1, Pass Labs Aleph 3, to Dunlavy SC-IVs (with the Vifa woofers). If you're not familiar with this older equipment, stereophile.com has comprehensive reviews. Basically, a 30W amp drives 91dBA speakers with flat extension below 30Hz. A 10W, 30Hz tone shakes the windows and various items in the room. Full-range horns would need 2-5W for similar effect. Of course, we're not talking about bookshelf speakers now. sthayashi (Hi, Steve!), has listened to Dark Side on my stereo. Maybe he will comment on its bass response.

For your needs, I think a pair of good monitors - PSB Alphas are the $200 choice - matched to a decent powered sub would be a good answer. But you live in Chicago, man! Go to a bunch of real hi-fi shops and listen before you spend more money. Spend 3 hours every Saturday for the next month, and you'll have a far better idea what you want. Listen to everything, no matter how expensive, just to see what you hear & think.

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Post by Sooty » Wed Mar 26, 2008 5:21 pm

What's this review got to do with silent computing? Oh I get it: you turn up the volume knob until you can't hear your noisy computer. Genius! :roll:

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Post by jessekopelman » Wed Mar 26, 2008 9:13 pm

niels007 wrote:Only hardcore / prejudiced / audio-idiots remain convinced class D can't work. Those who measure and listened simply said they are SUPERB at amazing efficiency.
Full power (50 or 100W/channel) A/V receivers based on Class D amps have been around for a while. I have a pretty nice Harman-Kardon model, circa a few years ago. Sadly, H-K got out of this game (bigger and heavier still sells to their core audience), but Panasonic still makes their very well respected SA-XR series. The main benefits of Class D are smaller form factor and better efficiency (= less heat to cook nearby components). Those benefits combine to let you place these amps in tighter spaces than you could otherwise get away with -- nice in this age of flat panel TVs and the like. That Panasonic seems to be standing alone reminds me of Mazda and the rotary engine.

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Post by kittle » Thu Mar 27, 2008 1:23 pm

matt_garman wrote: After I ended up with my not-as-good-as-I-hoped setup of Sonic Impact T-Amp and homemade speakers (based on the Audio Nirvana fullrange drivers), I spent a considerable amount of time searching the web for speakers that were high-efficiency enough to be powered by a tiny amount of power, but also had a decent low frequency range. I couldn't find any that didn't cost a fortune.

But I certainly could have overlooked them.
I dont think you did.
I went the same route looking for high-efficency drivers for my own DIY speakers. I looked and searched for the better part of 2 years and got nowhere.

But it all boils down to getting what you paid for.

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Post by tempeteduson » Sat Mar 29, 2008 3:16 pm

Devonavar wrote:I'd love to snag a T-Amp sample (and keep it), but I'm not getting my hopes up. Trimark, the company that made the chip inside went belly up about a year ago.
I think you meant Tripath. I remember reading a diyAudio.com forum thread some time ago about their going out of business, but I suspect that because many products still use these chips the existing supply is good. The follow-up T-Amp Gen 2 is quite new and still available (now at $50 but with included power brick).

I bought an original T-Amp from Parts Express when the hype just got started and hadn't yet pushed up the price (~$30). I was fairly impressed by it in terms of sound quality in the time I spent testing, but it is perhaps a little overrated. I found the amp to be bright compared to some Class-AB units I have (true in general for Class T, according to others), and subjectively it doesn't sound as effortless as them (okay, maybe "forced") owing to its low power capacity and my inefficient speakers. I would have modded the thing except that it's my only T-Amp and I would have risked ruining it. See here for the best modding advice.

Back to the thread at hand. I think the T-Amp gets the lion's share of exposure on low-cost, low-power Class D/Class T devices, but there are many other, more-expensive and better-sounding choices, the best competitor being the Trends Audio TA-10.1. I was previously unaware of this Scythe product and its star Yamaha chip, so thanks for the coverage. It seems the implementation is very sloppy judging by the interference issues, but then again, the company does not specialize in audio. Another option specifically for computer users is the SilverStone Ensemble EB02 (based on a slightly different Tripath chip), designed as a complement to SilverStone's quite-well-received EB01 USB DAC. It'd be great if you guys could get this particular one in for testing, since I haven't found any reviews.

I feel compelled to mention the Winsome Labs Mouse as the sole Class-T amp I've found that is head-and-shoulders above all others in terms of power output, and seems to me the best design. Granted, it starts at $320 in kit form and is not aimed at computer use, but audio enthusiasts wouldn't mind. Even at this price level, the Mouse still exhibits a hint of brightness that may be inherent to Class-T topology.

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Post by Olaf van der Spek » Mon Mar 31, 2008 7:47 am

This is all an amplifier should ever need.
What about a switch to enable the headphone output for people that would prefer to keep the headphones always connected?

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