I am looking for either an integrated amplifier, or an amp with level
controls on the front. It will drive a pair of Tannoy Reveal speakers
(specs at "http://www.tannoy.com/Default.asp?Id=4246"). The source will
be a computer. I am looking for something compact, with passive cooling
(no fan). The tricky part is that I'm on a budget. My goal was to
spend not much more than $300 on speakers and amplification, and I just
spent close to $200 for the speakers. So, I'm looking at the
$100-$150 price range. So far, these are the models I'm considering:

AudioSource Amp Two (80 wpc amp)
Pioneer Elite A-35R (45 wpc integrated)
Rotel receiver/integrated?


Obviously I'm not going to get any of these new for $100-$150, so
I've been looking on ebay. I'd like to stay away from larger
receivers, just because I'd like something compact. Any suggestions?

-Greg

It seems that most people use Hafler amps to drive these speakers. I
might be able to find one at a price I can afford on ebay. The P1000 is
the only one with RCA inputs though. The rest only have balanced
inputs. I'm trying to figure out if my soundcard (Chaintech AV-710) has
a strong enough signal to connect it directly to an amp, and if it's
possible to go from the unbalanced output of my soundcard to the
balanced input of one of the bigger Haflers. So...

Do I need a preamp if I get an amplifier instead of an integrated
amplifier?
Should I consider an amp that only has balanced inputs?

Any advice would be greatly appreciated.

-Greg

"Greg" wrote in message
oups.com...

a strong enough signal to connect it directly to an amp, and if it's
possible to go from the unbalanced output of my soundcard to the
balanced input of one of the bigger Haflers. So...

You need to know what the soundcard's maximum output voltage is, and what
the gain of the amplifier is. This will tell you what voltage the amplifier
can produce in the speaker outputs when driven by your soundcard, and you
can decide if that will meet your needs.

The Hafler P1500 for example has a gain range of 14dB to 29dB, which means
the output voltage is a maximum of 28 times the input voltage (the voltage
multiplier for a gain of x db is 2^(x/20).)

According to the spec, the balanced input sensitivity varies from 437mV to
2.4 volts per phase for an 8-ohm load. The voltage of a balancedsignal is
twice the voltage per phase - so the 437mV per phase input is an RMS voltage
of 875mV, which multiplied by 28 gives an output voltage of 24.6V RMS. With
8-ohm speakers, that's a current of about 3 1 amperes, which into an 8ohm
load is 75 watts - exactly what the P1500 spec says.

If you were driving with a 0.5 volt unbalanced input, the maximum output
would be 14 volts, which into 8 ohms is 1.75 amperes for a power output of
about 25 watts. However, into 4 ohms, the 14 volts would be 3.5 amperes,
and just over 40 watts of output power.

I should think it's best to avoid pre-amplifiers. Assuming you won't
operate the amplifier at full power anyway, all you'd be doing is improving
the S/N ratio of the amplifier section, but unless the pre-amplifier is
significantly better quality than the amplifier, the noise introduced by the
pre-amplifier will be the same as the noise avoided in the amplifier by
boosting its input. If the sound card output is inadequate, it might be
cheaper to change the sound card.

However, if you want to boost unbalanced sound card output for use with
balanced amplifiers, one way woud be to build a balanced line driver. There
really isn't. very much to these ...a dual op-amp and a few resistors,
probably about $5-$6 dollars worth of components, plus whatever connectors
yo use.. The power supply is the awkward thing. Most op-amp circuits are
shown with +-15 volt supplies, but I've had success using +-6 volts, powered
by AA batteries.

There's a single-channel circuit here; you can use a different op-amp if
you prefer.

http://sound.westhost.com/project51.htm

Tim

"Greg" wrote in message
oups.com...
It seems that most people use Hafler amps to drive these speakers. I
might be able to find one at a price I can afford on ebay. The P1000 is
the only one with RCA inputs though. The rest only have balanced
inputs.
I'm trying to figure out if my soundcard (Chaintech AV-710) has
a strong enough signal to connect it directly to an amp, and if it's
possible to go from the unbalanced output of my soundcard to the
balanced input of one of the bigger Haflers. So...

Sound cards have enough output to do this.

Do I need a preamp if I get an amplifier instead of an integrated
amplifier?
No.

Should I consider an amp that only has balanced inputs?
All you need is an unbalanced RCA to 1/4" adaptor, one for each channel. A
couple bucks each.

Any advice would be greatly appreciated.

-Greg

A preamp is useful, but not essential. It allows you to trim the levels for
optimal soundcard performance.
I would still go with the Hafler, as it is the highest quality of what
you've mentioned.

"Tim Martin" wrote in message
...

"Greg" wrote in message
oups.com...

a strong enough signal to connect it directly to an amp, and if it's
possible to go from the unbalanced output of my soundcard to the
balanced input of one of the bigger Haflers. So...

You need to know what the soundcard's maximum output voltage is, and what
the gain of the amplifier is. This will tell you what voltage the
amplifier
can produce in the speaker outputs when driven by your soundcard, and you
can decide if that will meet your needs.

The Hafler P1500 for example has a gain range of 14dB to 29dB, which means
the output voltage is a maximum of 28 times the input voltage (the voltage
multiplier for a gain of x db is 2^(x/20).)

Tim, the dB is a base 10 logarithm, so the correct formula for voltage gain
is 10^(x/20) .

Wow, thank you Tim and Robert. It sounds like I don't have much to
worry about, and will keep an eye on ebay for a P1500 or (preferably)
P3000. From what I read, the Tannoy Reveals do quite a bit better with
a high-watt amplifier.

I know this is an old question, but how does something like the P3000
compare to consumer amplification (decent brands, like Marantz, Denon,
etc.)? If I got a Hafler amp now, would I want to connect it to the
pre-outs of a surround receiver in the future?

-Greg

http://www.swee****er.com/store/detail/Servo120a/

Greg wrote:
I am looking for either an integrated amplifier, or an amp with level
controls on the front. It will drive a pair of Tannoy Reveal speakers
(specs at "http://www.tannoy.com/Default.asp?Id=4246"). The source will
be a computer. I am looking for something compact, with passive cooling
(no fan). The tricky part is that I'm on a budget.

I'd try driving around and visiting local pawn shops to look for used
amps and receivers. Make sure to try before you buy.

eBay is another alternative, but it's easier to check for problems
(such as hum) when you shop at local stores.

(snip)

"Greg" wrote in message
oups.com...
Wow, thank you Tim and Robert. It sounds like I don't have much to
worry about, and will keep an eye on ebay for a P1500 or (preferably)
P3000. From what I read, the Tannoy Reveals do quite a bit better with
a high-watt amplifier.

I know this is an old question, but how does something like the P3000
compare to consumer amplification (decent brands, like Marantz, Denon,
etc.)? If I got a Hafler amp now, would I want to connect it to the
pre-outs of a surround receiver in the future?

-Greg

I have a P3000. It is a superb amplifier, much better than the brands you
have mentioned.
In fact, I consider it in the top rank of all amplifiers.
You can connect it to pre-outs. It's much better than the sound of any,
perhaps all, receivers.

"Robert Morein" wrote in message
news
Tim
The Hafler P1500 for example has a gain range of 14dB to 29dB, which
means
the output voltage is a maximum of 28 times the input voltage (the
voltage
multiplier for a gain of x db is 2^(x/20).)


Robert
Tim, the dB is a base 10 logarithm, so the correct formula for voltage
gain
is 10^(x/20) .

Thanks, that's correct. I wrote it wrong. I did the calculations correctly
though ... :-)

So the output voltage is a maximum of 28 times the input voltage.

Tim