phurbs

[NEWBIE] Hello from a new Wammer! Plus, a question

25 posts in this topic

Hello All!

Firstly, for reasons which will become clear, I wanted to say that I have found this forum invaluable recently, as I have been taking my first steps in to the HiFi world!

A little background, I am 28yr old normal bloke with normal hobbies, especially where tech is involved! I am also a man who loves his music. With a passion. Now, given that these two things are true, it seems surprising that I am only just taking my first steps into what I hope will be a rewarding world of HiFi! But, it is true nonetheless.

Now, I do ALL my music listening on my PC. Always have done. The weird thing is, despite being anal about the quality of my digital music (High Bit-Rate MP3 / FLAC) up until now, I have been making do with an PC on-board soundcard and some little Creative speakers with a sub. However, this is about to change, as I have decided to move into the shallow end of audiophilery! Hopefully it will just be the start!

So, after reading every post in the the epic near-1000 post thread started by JANDL100 devoted to the MiniT Amp, I have decided to make a £60 purchase. Namely this ORDO T-Amp. The unit has a TA2020 main amp, with on-board USB DAC and TA2024 'phone amp.

My 1st question is, have I done OK with my choice of unit? I know it isn't the T-Amp that was raved (or flamed :)) about in the thread, but Chinese no-name aside, I think it hits all the same buttons?

My 2nd question is, what speakers to pair up with it? I have a few weeks to decide while the amp is shipped, so there is no rush, but I was hoping to make a decision and get the speakers long before it arrives!

Now, from what I have read, these amps work best with a high sensitivity speaker (88db+) and with a low-ish impedance so as to pull the maximum wattage out of the unit. Leaving alone that I still dont quite understand impedance (I am working on it lol) I am looking for some decent bookshelf speakers to get my started. The speakers need to be small (they are going on my desk) and will be backed up against a wall, so rear facing bass ports would be better I think?

With this in mind, I have found some cheapo 2nd hand ebay numbers I was hoping to get some feedback on. Namely, some Gale Silver Monitors (£20 from ebay) which I think are a decent first step? They have a sensitivity of 88db and are rated at 6Ohms for impedance, with rear facing bass ports.

The idea, going forward, will be to improve in sections, start with the speakers, then back to the Amp, then back to the speakers etc . . .

So, any advice? :)

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I think one thing you should be considering is binning the MP3 files. Once you get past the boggo soundcard/cheapo computer speakers stage, the shortcomings of (even high bit-rate) MP3 are completely obvious and you'll find yourself becoming frustrated. FLAC is better, but I'm not into computer audio so won't offer any further advice about file formats beyond that.

If you're intending to listen to your music while sat at the computer, then you'll want speakers which work in the 'nearfield' ie a metre or two from your ears at most. If so, most of the 'domestic speakers won't be ideal. I've had some stunning results in such circumstances from Eclipse TD speakers (508's) with their 501 amp which is also a class D design. If you're going to set up in a room and listen in a more conventional way, then I'm sure others will offer thoughts on speakers, personally I like the baby Focals, such as the Chorus 705, but they don't spare your feelings if the amp is a bit on the rough & ready side.

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Dealer

T-amp, best thing to hit the streets since the LP-12 imo. :)

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Gale speakers are cheap and nasty, I'd pass on them. I've seen Kef iQ1s sell for £60 or so and they would do nicely, as would some B&W 685s. Of course, this being the Wam, there may be a few interesting speakers lurking in attics...

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a link to the T-amp but not the speakers got to love a bit of free advertising

I know I am new here, but I think it is clear I am not advertising! Given the word count of my post, a single link doesn't really scream out as being over the top! Plus, I wasnt raving about the product. Infact, I was asking for feedback!

As for the Gales, I know they are cheap, I am looking to get myself started! That said, no point buying something totally sh*te. How would some Wharfedale 9.0s rate?

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Rogers LS2a would be my pick. Wharfedale 9.0s are fine - I use some with my T-amp with the computer :^

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"A little background, I am 28yr old normal bloke with normal hobbies, especially where tech is involved! "

Welcome phurbs, but you will find normality a bit of a drawback here, as we are all as mad as a box of frogs!! Seriously though, don't forget to acquire a silly avatar and signature. Good luck on your (perhaps "long and winding") road to hi-fi nirvana. I am particularly fortunate to have recently almost arrived there, having acquired (at reasonable cost) CHORD pre/power amplifiers(CPA2800/SPM800). This duo will be my final amplification.........probably.

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Hmm. Looks like I can get some Wharfdale9.0s for a similar price to the Gales. Only difference is a slightly lower sensitivity (86 vs 88) but I am assuming this will not be noticeable over the short cable length (1.5m max)?

Alternatively, they are over budget, but what about some B&W Vision DS1s? Seen some on ebay for £100. Worth the extra? I am struggling to find specs . . .

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The cable length will not affect sensitivity. A 2dB difference in sensitivity is actually quite significant - I would really advise looking for something more sensitive.

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"A little background, I am 28yr old normal bloke with normal hobbies, especially where tech is involved! "

Welcome phurbs, but you will find normality a bit of a drawback here, as we are all as mad as a box of frogs!! Seriously though, don't forget to acquire a silly avatar and signature. Good luck on your (perhaps "long and winding") road to hi-fi nirvana. I am particularly fortunate to have recently almost arrived there, having acquired (at reasonable cost) CHORD pre/power amplifiers(CPA2800/SPM800). This duo will be my final amplification.........probably.

Thanks for the welcome! (That goes for everyone btw :)) When I say normal, it is obviously an open ended term! I will make sure I work on my avatar and sig though! I am really looking forward to working my way up the ladder of steadily improving kit. It has always been an ambition to own a seriously kick ass stereo. I am starting small, but I will get there!

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Now, from what I have read, these amps work best with a high sensitivity speaker (88db+) and with a low-ish impedance so as to pull the maximum wattage out of the unit.

There are a couple of misconceptions in this part of the OP which might be helpfully clarified here.

Firstly, sensitivity relates to the number of decibels which the speaker will put out (at a given frequency) for each watt of amplifier power input to them. So, sensitivity relates to maximum loudness you can get from a given power output. It's a logarithmic scale, and a 3dB increase in sensitivity equals a doubling of the loudness for a given power, so an 88dB sensitivity speaker will sound twice as loud as an 85dB sensitivity one, for the same amplifier output. This is mainly of importance if your amplifier is of very low power and/or the speakers are of very low sensitivity, when you may find yourself turning the volume up to get reasonable sound levels. That, in itself, isn't a problem until you turn the volume up too high, and the amplifier starts to 'clip', which a) sounds nasty and b) can damage your tweeters. I'm not that familiar with class D amps, like the T-amp, so I don't know if their clipping characteristics are different in any significant way to those of a regular class A/B design.

Secondly, impedance. As a rule, higher impedance helps amplifiers which can't produce a lot of current, a 4Ohm impedance will require twice as much current (Amps) as an 8Ohm impedance, for the same power output from the amplifier. What this means is that, if your amplifier can produce, say, 15Amps max, a higher impedance speaker will make better use of the amplifier output than a lower impedance one, which might require 30Amps for the same power output, hence your amp may fail to deliver its maximum potential. So low impedance doesn't 'pull' maximum wattage, it 'demands' higher current. If the amp can't deliver that current, it will give whatever lower current it is capable of in the circumstances, which equates to lower wattage.

I'm assuming the T-Amp is fairly low power, most class D amps are around are 20-25 Watts, so it'll also be comparatively low current. Therefore, a reasonably sensitive design (88-90dB) and reasonably high impedance (6-8 Ohms) will make life easier for your amp.

Another point concerning the comment about rear-facing ports being good for up against the wall. I'd suggest the reverse is true, if you put a rear-ported loudspeaker against the wall, the port won't work as intended as it can't 'breathe' properly. Better to use either a sealed (not-ported) design, or a front-ported one.

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If you are going up to £100 for the speakers, to go with the T-Amp, i would look into the following-

Rega Kyte or Rega R1

Tannoy DC1000 (a bit larger but work well close to rear walls)

Keesonic Kubs (very rare but perfect for your application)

I would steer clear of the Gale/warfedales personally you ideally want speakers that are a sealed design, or front ported at a push Have you considered DIY? A full range driver in a simple sealed box would go perfectly with the T-Amp, wont cost the earth and will be fun to do!

http://www.hifiwigwam.com/showthread.php?56463-Smaller-corner-speakers

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I know I am new here, but I think it is clear I am not advertising! Given the word count of my post, a single link doesn't really scream out as being over the top! Plus, I wasnt raving about the product. Infact, I was asking for feedback!

As for the Gales, I know they are cheap, I am looking to get myself started! That said, no point buying something totally sh*te. How would some Wharfedale 9.0s rate?

I think that is obvious to all but the dimmest among us :roll:

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There are a couple of misconceptions in this part of the OP which might be helpfully clarified here.

Firstly, sensitivity relates to the number of decibels which the speaker will put out (at a given frequency) for each watt of amplifier power input to them. So, sensitivity relates to maximum loudness you can get from a given power output. It's a logarithmic scale, and a 3dB increase in sensitivity equals a doubling of the loudness for a given power, so an 88dB sensitivity speaker will sound twice as loud as an 85dB sensitivity one, for the same amplifier output. This is mainly of importance if your amplifier is of very low power and/or the speakers are of very low sensitivity, when you may find yourself turning the volume up to get reasonable sound levels. That, in itself, isn't a problem until you turn the volume up too high, and the amplifier starts to 'clip', which a) sounds nasty and b) can damage your tweeters. I'm not that familiar with class D amps, like the T-amp, so I don't know if their clipping characteristics are different in any significant way to those of a regular class A/B design.

Secondly, impedance. As a rule, higher impedance helps amplifiers which can't produce a lot of current, a 4Ohm impedance will require twice as much current (Amps) as an 8Ohm impedance, for the same power output from the amplifier. What this means is that, if your amplifier can produce, say, 15Amps max, a higher impedance speaker will make better use of the amplifier output than a lower impedance one, which might require 30Amps for the same power output, hence your amp may fail to deliver its maximum potential. So low impedance doesn't 'pull' maximum wattage, it 'demands' higher current. If the amp can't deliver that current, it will give whatever lower current it is capable of in the circumstances, which equates to lower wattage.

I'm assuming the T-Amp is fairly low power, most class D amps are around are 20-25 Watts, so it'll also be comparatively low current. Therefore, a reasonably sensitive design (88-90dB) and reasonably high impedance (6-8 Ohms) will make life easier for your amp.

Another point concerning the comment about rear-facing ports being good for up against the wall. I'd suggest the reverse is true, if you put a rear-ported loudspeaker against the wall, the port won't work as intended as it can't 'breathe' properly. Better to use either a sealed (not-ported) design, or a front-ported one.

Can I also clear up a misconception to the clearing up of the misconception. :dunno:

3dB is indeed a doubling of power, but not a doubling of loudness. 3dB is only very slightly louder, it takes some 10dB of power increase i.e 10x to sound twice as loud. This is because our hearing is logarithmic, not linear.

As to the effects of impedance, an amplifier is a voltage source. That means that within it's capabilities, it will put out a constant voltage regardless of load impedance. A 100 watt into 8 ohms amplifier generates 28.3 volts on its output. Power is voltage squared divided by impedance, so 28.3 x 28.3 /8 = 100 If the amplifier is now loaded with 4 ohms, it will draw 28.3 x 28.3/4 =200 so now the 100w into 8 ohm amplifier delivers 200 watts into 4 ohms. Real-world amplifiers don't all double their power into half the laod, but some do, and it's one sign of a good amplifier.

However, as Vlad suggested, going from 8 ohms to 4 ohms will draw double the current and if the amplifier isn't capable of driving this current requirement, distortion will rise dramatically. Note that 28.3 volts into 8 ohms is 3.5 amps, into 4 ohms it's 7 amps rms or 10 amps peak. To drive a 4 ohm loudspeaker to full power, a 100 watt amplifier must be capable of driving +-10 amps peak.

S.

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