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Old 1st September 2011, 10:08 AM   #1
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Default noob question about sure's 2x100W amp

I know very little about the subjects that are discussed on this forum, however, I hope someone can answer my (pretty dumb) question anyway.

I have 2 B&W speakers with the following specifications:
[spoiler]Description: 2-way 4th order, ported bass reflex
Drive Units:
digital monitor system with bi-wiring/biamplification facility
1 x 26 mm high-frequency with metal dome
1 x 200 mm bass/midrange with rigid die-cast chassis, reinforced propylene diaphragm and 31mm high temperature voice coil
Frequency Response: 70 Hz 20 kHz 2dB on reference axis
Sensitivity: 90 dB spl(2.83V 1m)
Nominal impedance: 8 ohms
Power Handling: 25 W 100 W into 8 ohms on unclipped programme[/spoiler]

I was wondering whether the amp in the thread title would work with those speakers. I am interested in a decent amp for not a lot of money, but I was dumb enough to buy a 20W 4ohm amp which (obviously?) doesn't work with the mentioned speakers.

Could you help me please, so I don't make the same mistake I made before? The people in this forum seem to know an awefull lot about the subject, I hope this is not regarded as spam, despite the fact that I'm fully aware of the fact that this is a pretty dumb/easy question for people who visit this forum.

Thanks a lot.
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Old 1st September 2011, 01:07 PM   #2
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I'll try to help, but it isn't such an easy question to answer without a bit more information.

The Sure amp has sufficient power to drive you speakers and as such should 'work'. There are other alternatives generally regarded here as better quality and still not expensive, as just one of many you might like to also look at something like Hifimediy T1 ALPS sta510A 2*100W@8ohm amplifier | |Hifimediy.

That said your 20W@4 Ohm amp should also 'work' although unlikely to go so loud. There are some other gotchas that might hit you even with the larger amps, so as a quick sanity check:

- What music sources are you going to connect to the amp?
- Will a pre-amp be used or are you connecting source to amp directly?
- How big is your room?
- What sort of music will you listen to and how loud do you want it?

Lastly, what do you mean by the smaller 20W amp not working?
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Old 1st September 2011, 01:44 PM   #3
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Quote:
Originally Posted by goosewing View Post
That said your 20W@4 Ohm amp should also 'work' although unlikely to go so loud. There are some other gotchas that might hit you even with the larger amps, so as a quick sanity check:

- What music sources are you going to connect to the amp?
- Will a pre-amp be used or are you connecting source to amp directly?
- How big is your room?
- What sort of music will you listen to and how loud do you want it?

Lastly, what do you mean by the smaller 20W amp not working?
Thank you for your reply. I will now try to answer your questions.

First, what I mean by 'the smaller 20W amp not working'?
Well, it's pretty simple really. A friend of mine ordered the lepai 20W@4ohm amp, replaced his T-amp with it, and it worked fine. I collected it, connected my ipod to the jack input, and connected the speakers, it didn't work (lights did though). Then I tried connecting my pc instead, tried connecting to the RCA, all didn't work. So I went to a nearby technics shop, and I asked the guy behind the counter whether he knew something about amps, and he said it was a hobby of his, and he was into modding/repairing/etc. amps. He said it was unlikely it'd work, because the speakers required a 'minimum power' input. The speakers would only start working at a certain level, he said it was probably 50W@8ohm. I figured he knew what he was talking about, so accepted I bought the wrong amp. What I mean by my amp not working thus, is, it doesn't work with my speakers, it does with my friend's.

The music source I'd connect to the amp is my pc (simple creative sound card). Since I don't use cd players, AM/FM, and I'd really only connect my pc to it, i figured a simple amp with 1 input and such great reviews would be fine for me. Simple, cheap, yet quality, it was exactly what I needed.

The room I'd use it for is pretty small (~10 square meters). That would imply it might be a better idea to sell the speakers and get a smaller set of speakers for my 20W@4ohm amp. However, the speakers were a gift, are of good quality, and getting a bigger amp/speaker set would offer flexibility. I would have a decent setup, even if i'd move it to a larger environment.

I listen to all sorts of music, dillinger escape plan, meshuggah, but also deftones, mars volta, radiohead, but also dubFX, immortal technique, yet even classical music and jazz from time to time. I never really looked at 'what music the amp is best suited for' since I listen to such a wide variety.

Again, thanks for replying to my inquiry, and I will check out the amp you mentioned.

EDIT: your link didn't work, on ebay I can't find hifimediy amps either, only boards.

Last edited by helemaalnicks; 1st September 2011 at 02:08 PM.
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Old 1st September 2011, 02:23 PM   #4
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OK, either of the Sure or Hifimediy amps should be fine for your setup with a sound card driving them. Folks here do get good sound from the Sure amp - but if you read the messages here you will see that there is quite a bit of DIY modification going on to get there - with the suggested alternative it has good parts quality to start with and the mods aren't necessary.

With a soundcard input you should be OK. I do suggest getting one of the amp modules with volume pot on board as this will allow you to run your soundcard output at max without digital attenuation - and this should improve noise levels.

Lastly, the audio techie you talked to talked cr*p I'm afraid. Fact is music has something like a 10:1 ratio between average listening level and peaks and so even that 20 Watt (probably 10 watt into 8 Ohms) amp would be able to produce decent average sound levels - it just wouldn't be able to go loud enough on the loud bits. You'll probably find that at normal listening levels your amp, even the 100w one, is only putting out 3 or 4 watts most of the time. Therefore if you had no sound at all something else was wrong not the amp's output power.

I would double check the cabling and also check your speakers work with a different amp - just in case it is them at fault. If your amp worked fine with different speakers and there is no sound at all from yours - you can virtually guarantee there is a simple connection fault somewhere. (or a problem with the source, also check the same source set-up playing into something else).
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Old 1st September 2011, 02:30 PM   #5
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[QUOTE= your link didn't work, on ebay I can't find hifimediy amps either, only boards.[/QUOTE]

Their site had problems recently and suggests that if anyone has problems connecting they should try clearing their browser cache. . You are quite right and the link to individual amp doesn't seem to work, this one goes to its parent page http://hifimediy.com/?page_id=18&category=1 or 'hifimediy' as a google search term will find them.

Their amps are on ebay but not always the full range. A quick check shows this one Hifimediy T1 ALPS TK2050 2*80W STA508 tripath amplifier | eBay which is almost the same, a little cheaper but not quite as powerfull. Either would do fine.

Last edited by goosewing; 1st September 2011 at 02:33 PM.
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Old 1st September 2011, 02:32 PM   #6
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It was much easier when i thought it shouldn't work. Now I obviously don't buy a new amp until i've figured out the real problem. Gonna do another round of testing, thanks for replying.
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