[[email protected]]

Hi there,

Could anyone please tell me if I could power my passive BM15s
with a Technics integrated amplifier, which specs a
4 ohm, 1 khz continuous power output both channels driven 2x100W,
63-12,5 kHz continuous power output both channels driven 2x85W?
If so, is there going to be any difference to my QSC USA 900 power
amplifier
(2x450W at 4 ohm) at all? I've read that amplifier has to be powerful
enough
to fully drive speakers (especially low frequencies),
others say that there is no diference in the amps at all, and that
they all
sound the same with volumes matched, unless they are overdriven.

Is the Technics amp powerful enough and can it drive these speakers
properly?
Is there going to be any loss in the lower frequency range?

Another question: Is it possible to burn/damage the speakers or the
amp
because the amp is not powerful enough? How loud you'd need to get the
volume in this case?

Thank you so much! I appreciate it!

Ray

[Scott Dorsey]

wrote:

Could anyone please tell me if I could power my passive BM15s
with a Technics integrated amplifier, which specs a
4 ohm, 1 khz continuous power output both channels driven 2x100W,
63-12,5 kHz continuous power output both channels driven 2x85W?

Sure. If it starts to clip, turn it down. You can use any amplifier
as long as you don't care about sound quality.

If so, is there going to be any difference to my QSC USA 900 power
amplifier
(2x450W at 4 ohm) at all?

Yes.


I've read that amplifier has to be powerful
enough
to fully drive speakers (especially low frequencies),
others say that there is no diference in the amps at all, and that
they all
sound the same with volumes matched, unless they are overdriven.

All of these are true. The thing is, you want an amplifier to have a
really low output impedance to drive the low end well. The easiest way
to assure that is to get a powerful amp.

But, the BM15 is pretty efficient and will work fine with a small amp,
as long as you don't clip the amp.

Is the Technics amp powerful enough and can it drive these speakers
properly?
Is there going to be any loss in the lower frequency range?

The Technics is a total piece of crap, and I would be more worried about
that than about the power rating. Try the two out for yourself and
you'll understand what I mean.

Another question: Is it possible to burn/damage the speakers or the
amp
because the amp is not powerful enough? How loud you'd need to get the
volume in this case?

It is possible. Don't clip the amp and you'll be fine. Let me repeat
this: don't clip the amp. If it starts to sound bad, turn it down.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

Thanks for your answers Scott! I appreciate that!

The Technics is a total piece of crap, and I would be more worried about
that than about the power rating. Try the two out for yourself and
you'll understand what I mean.

That just amazes me. I can probably understand if there isn't enough
wattage to power up the speakers, as for sound quality of the Technics
amp (it's a SU-A800DM2), it's amazingly clean and powerful. In my own
experience, I haven't noticed any difference at all while comparing
these those above mentioned amplifiers.

These are a couple of links that you will probably find interesting:

http://www.hometheaterfocus.com/rece...d-quality.aspx

http://www.matrixhifi.com/contenedor_ppec_eng.htm


What do you think about that?

Cheers!

Ray

[Scott Dorsey]

wrote:
Thanks for your answers Scott! I appreciate that!

The Technics is a total piece of crap, and I would be more worried about
that than about the power rating. Try the two out for yourself and
you'll understand what I mean.

That just amazes me. I can probably understand if there isn't enough
wattage to power up the speakers, as for sound quality of the Technics
amp (it's a SU-A800DM2), it's amazingly clean and powerful. In my own
experience, I haven't noticed any difference at all while comparing
these those above mentioned amplifiers.

These things use really noxious-sounding hybrid output modules which are
run as far into class B as they can get away with, in order to keep the
heatsink costs down. The top end on them tends to be very harsh.

Do an A-B comparison between the thing and any one of the mid-priced home
stereo amps with discrete output stages, and you'll hear a surprising
difference.

These are a couple of links that you will probably find interesting:

http://www.hometheaterfocus.com/rece...d-quality.aspx

http://www.matrixhifi.com/contenedor_ppec_eng.htm

What do you think about that?

I think anyone citing Stereo Review about anything ought to be ashamed
of themselves. Also I think even the cheap Behringer in that second listening
test is a step up from the Technics. Give it a listen and see.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[david correia]

In article
,
wrote:

Thanks for your answers Scott! I appreciate that!

The Technics is a total piece of crap, and I would be more worried about
that than about the power rating. Try the two out for yourself and
you'll understand what I mean.

That just amazes me. I can probably understand if there isn't enough
wattage to power up the speakers, as for sound quality of the Technics
amp (it's a SU-A800DM2), it's amazingly clean and powerful. In my own
experience, I haven't noticed any difference at all while comparing
these those above mentioned amplifiers.



If you've got any friends with a Bryston amp, borrow them for an hour
and listen to your Dynaudio's. Your speakers will not sound the same,
particularly the top end.

Another idea is to call Dynaudio's tech support and see what amp(s) they
recommend. Tell them what you think.

Scott ain't blowing smoke at you.






David Correia
www.Celebrationsound.com

[Eric B]

On Oct 16, 12:59*pm, wrote:
Hi there,

Could anyone please tell me if I could power my passive BM15s
with a Technics integrated amplifier, which specs a
4 ohm, 1 khz continuous power output both channels driven 2x100W,
63-12,5 kHz continuous power output both channels driven 2x85W?
If so, is there going to be any difference to my QSC USA 900 power
amplifier
(2x450W at 4 ohm) at all? I've read that amplifier has to be powerful
enough
to fully drive speakers (especially low frequencies),
others say that there is no diference in the amps at all, and that
they all
sound the same with volumes matched, unless they are overdriven.

Is the Technics amp powerful enough and can it drive these speakers
properly?
Is there going to be any loss in the lower frequency range?

Another question: Is it possible to burn/damage the speakers or the
amp
because the amp is not powerful enough? How loud you'd need to get the
volume in this case?

Thank you so much! I appreciate it!

Ray

Ray,
Dynaudio's design philosophy leans toward quality over efficiency.
Most of their speakers are a bit lower in efficiency than other
brands, but handle way more power. That said, the Technics will work
fine unless you want to get really loud with lots of deep bass. Beware
the little know fact that under powering a speaker will blow it out
faster than over powering it, due to clipping distortion. The Technics
being a hifi piece probably doesn't say when it is clipping. The
Bryston 2B or 4B is a much better alternative. Look on line for used,
sometimes they are available for $5 or 600. If this scares you stay
with the Technics and keep an eye out for a fast, powerful respectable
amplifier. I think the BM15s are rated at 150 watts but has been a
long time since I needed to know that spec.
Party on.
Eric Blackmer

[Arny Krueger]

wrote in message

Hi there,

Could anyone please tell me if I could power my passive
BM15s with a Technics integrated amplifier, which specs a
4 ohm, 1 khz continuous power output both channels driven
2x100W, 63-12,5 kHz continuous power output both channels
driven 2x85W?

Yes you can, and you will obtain some predictable results.

For example, they are rated at 88 dB/W at one meter (actually relevant as
stated if you use them as near fields).

In rough numbers your amp's output is 20 dB above 1 watt, so we're talking
108 dB at amp clipping presuming no compression in the speakers. You
speakers are capable of over 120 dB, so you aren't going to be able to
fully exploit their dynamic range. OTOH, your ears will thank you if you
don't actually exploit their dynamic range in the near field.

I've had speakers that put out 108 dB @ 1 meter at amp clipping, and they
were loud but not awe-inspiring in actual listening room (intermediate
field) use.

If you follow the 85 dB rule for monitoring, probably no problem.

If so, is there going to be any difference to my QSC USA
900 power amplifier (2x450W at 4 ohm) at all?

Two things for sure - the USA 900 has a fairly noisy fan, and 450 watts is
about another 6 dB worth of power.

I've read that amplifier has to
be powerful enough
to fully drive speakers (especially low frequencies),

These speakers aren't subwoofers, they are speced to be rolling off pretty
significantly below about 40 Hz.

others say that there is no difference in the amps at all,
and that they all sound the same with volumes matched, unless they are
overdriven.

The chances of overdriving the Technics integrated amp is greater than the
chances of overdriving the QSC.

Is the Technics amp powerful enough and can it drive
these speakers properly?

Depends on the room and your expectations.

Is there going to be any loss in the lower frequency
range?

That is probably the least of your problems since the speakers are always
going to be arguably marginal on the bass end unless you add a subwoofer.

On balance, monitoring with speakers that roll off below 40 Hz is not
necessarily a problem unless you are mixing rap or other material that is
very dependent on strong low bass. A speaker with a 40 Hz roll-off is not
going to tell you what your customers with large systems are hearing. Of
course if like me you don't have many customers like that, and you don't
make them a priority, then these speakers will probably be fine as is.

If you don't like these speakers, I'll pay shipping from anyplace in the 48
states to my house. ;-)

Another question: Is it possible to burn/damage the
speakers or the amp because the amp is not powerful enough?

That's an old argument, and after long consideration, I'd say that maybe
yes, maybe no, but probably not.

How loud you'd
need to get the volume in this case?

I think that anybody who actually tries to get 120 dB out of these boxes
is playing with fire. ;-)

[Peter Larsen[_3_]]

Eric B wrote:

On Oct 16, 12:59 pm, wrote:
Hi there,

Could anyone please tell me if I could power my passive BM15s
with a Technics integrated amplifier, which specs a
4 ohm, 1 khz continuous power output both channels driven 2x100W,
63-12,5 kHz continuous power output both channels driven 2x85W?

Yes you can, but you need to align things and use markers or whatever so
that you KNOW that it doesn't clip.

If so, is there going to be any difference to my QSC USA 900 power
amplifier (2x450W at 4 ohm) at all?

You have a strange way of thinking, as explained by Arny it is capable of
being loud enugh for sane listening, but what worries me is that you do not
seem to consider sound quality to be a parameter.

I've read that amplifier has to be powerful enough
to fully drive speakers (especially low frequencies)

An amplifier should not clip or otherwise overload, that's all there is to
that. Note the wording "otherwise overload", some designs were considerably
better at driving resistors than at driving loudspeakers because
loudspeakers are quite complex loads that are likely to require current to
flow when the voltage driving the is zero. This is caused by the phase
difference between voltage and current in a circuit with complex impedance.
I recall an amplier test that came to the conclusion that a 2 X 300 watts
amp should have its spec altered to read 2 X 11 watts due to the actions of
its protection circuitry when loaded with a real loudspeaker.

others say that there is no diference in the amps at all, and that
they all sound the same with volumes matched, unless they are overdriven.

Yes, I have heard that too. Not all agree, but it IS relevant to be aware
that you do not need more power than you need, you just need to avoid
"clipping and otherwise overloading". You don't need more, and there are
small amps out there with great punch and large ones that sound anaemic in
comparison. My basis for choosing the household poweramp in another age was
a method called listening.

Is the Technics amp powerful enough and can it drive these speakers
properly?

Dynaudio use a crossover strategy that should cause the loudspeaker to
constitute a benign load, interpreting "drive properly" to mean "able to
deliver the required current" I'd say yes to both and ask you how it sounds
compared to other poweramps. If you can't hear the difference in sonic
signature between different items of electronics you need to train "techie
listening". It is very differerent from "musicians listening" because it is
about listening for what should not be there rather than listening for what
is there. Can you hear the layers in a mix, can you hear the recorded rooms
ambinece signature, etc. etc. ...

Is there going to be any loss in the lower frequency range?

No.

Another question: Is it possible to burn/damage the speakers or the
amp because the amp is not powerful enough?

That is a silly way to circumscribe it, an amp that is "not powerful enough"
is an overdriven amp, and you of course align your setup so that amp
clipping is well beyond clipping whatever it is that feeds it AND so that
you know what peak SPL that corresponds to. 108 dB in the room from a dual
100 watt amp is "close enough" as a guess, and it is slighly louder than you
should listen IF you want to avoid hearing damage, ie. you have headroom
beyond the 100 dB instantanous peak that should be considered the clipping
point of the human ear, above that range the ears mechanical transmission
path starts to distort more than the brains autocorrelator can compensate.
In laymans terms: the louder it gets beyond 100 dB instantanous peak the
less you will hear, then AND afterwards.

How loud you'd need to get the volume in this case?

If you align it properly and it is not loud enough, then you need a bigger
amp. What matters with amps is not only whether they clip, but also HOW they
clip, an ill-behaved or partly faulty amp that goes into a short burst of
white noise instead of just "flat-topping" the waveform is in my experience
quite likely to damage treble loudspeakers even if only marginally clipped
and one that decides to take a lengthy trip to either plus or minus Vcc is
quite good at frying bass loudspeakers or anything else, all bets are also
off in case an amp decides to practice being a medium wave transmitter, ie.
goes into oscillation.

Large amps do more damage fast if things go wrong.

Dynaudio's design philosophy leans toward quality over efficiency.
Most of their speakers are a bit lower in efficiency than other
brands, but handle way more power.

It is their policy to aim for a 1 kWatt _peak_ powerhandling, but peak means
peak and comes with an exact defintion of for how long time and there may be
frequency range specs that go with it. Hotplug a phonoplug into a 1 kWatt
amp with is input attenuator fully open and anything can be blown up.

That said, the Technics will work
fine unless you want to get really loud with lots of deep bass. Beware
the little know fact that under powering a speaker will blow it out
faster than over powering it, due to clipping distortion. The Technics
being a hifi piece probably doesn't say when it is clipping.

His scope will tell him when he align things. Or a 30 dB attenuator and a
pair of headphones, but don't wear them, just hold then near enough so that
you can hear the very audible onset of clipping a sine wave, open output is
OK for that alignment .... just set max imput level to the power amp 2 dB
lower.

The
Bryston 2B or 4B is a much better alternative. Look on line for used,
sometimes they are available for $5 or 600.

I recently got me a second hand Yamaha P1600 and it is not, like their
P2200, slightly boring, I like it a lot. My grieance with the P2200 is not a
major one, and it could - by having metering - be a very good choice for the
OP's use. The P1600 has better inter-transient silence and a rock stead bass
range and is much better at doing violins and has much better ambience
detail, but the P2200 is OK and will tell you what you need to know about a
recording, even it it may keep quiet about how good it (the recording)
really is, I found one that appeared to be OK and got that one too, the aim
being biamping a small event rig via a CX 2300

Does Dynaudio have an amplifier sizing reocmmendation for those
loudspeakers?

Eric Blackmer

Kind regards

Peter Larsen

[Chris Hornbeck]

In addition to lots, and very high-Q, responses already posted,

On Sat, 18 Oct 2008 12:33:30 -0400, "Arny Krueger"
wrote:

wrote in message

Hi there,

Could anyone please tell me if I could power my passive
BM15s with a Technics integrated amplifier, which specs a
4 ohm, 1 khz continuous power output both channels driven
2x100W, 63-12,5 kHz continuous power output both channels
driven 2x85W?

For example, they are rated at 88 dB/W at one meter (actually relevant as
stated if you use them as near fields).

In rough numbers your amp's output is 20 dB above 1 watt, so we're talking
108 dB at amp clipping presuming no compression in the speakers. Your
speakers are capable of over 120 dB, so you aren't going to be able to
fully exploit their dynamic range. OTOH, your ears will thank you if you
don't actually exploit their dynamic range in the near field.

If you follow the 85 dB rule for monitoring, probably no problem.

All of the usual suspects, lounging around here on the corner, just
looking for trouble, like maybe a flareup between the Sharks and the
Jets..., or maybe something a little less gay (or whatever...) know
all about the 85 dB SPL monitoring paradigm (Brother, can you spare a
paradigm?) but the OP likely mightn't.

But it goes (very, very roughly, Tiger) like this: To establish a
reference acoustic volume level, the studio tech generates some
reference combination of sound outputs from all monitoring speakers
and measures acoustic level at the monitoring location(s). A reference
"0 VU" is decreed, or alternatively, a standard is accepted.

An earlier standard of 85 dB SPL or a later standard of 83 dB SPL
actually makes little difference in the finished product - we're
very adaptable critters. What matters is that we reference a sound
pressure level number ("0 dBVU") rather than some nebulous "amplifier
power" number expressed in (linear) dollars, rather than (log) sound.
This "0 dBVU" is our only real working reference point.

Amplifiers, their working range in active crossover systems, and even
their most important characteristics (ferzample, the design choice in
balancing small-signal performance with large-signal, or the
design choice in balancing local degeneration vs. global feedback)
are fundamentally affected by the choice of "0 dBVU".



An amplifier needs to be able to generate an SPL of at least 20dB
larger than the reference 0 dBVU and to have negligible distortion
through the dynamic range of (at least) 0 dBVU through -60 dBVU.

Doesn't sound like such a much, but getting that range perfect has
taken folks at least as smart as us a lifetime to approach.

The modern emphasis on the +20 dBVU end of the working range, for
advertising purposes, is often at the expense of the -60 dBVU end.

Doesn't have to be this way.



Much thanks, as always,
Chris Hornebck

"Beauty will save the world."
- Feodor Dostoevsky

"Information is not knowledge. Knowledge is not wisdom. Truth is not
beauty. Beauty is not love. Love is not music."
- Frank Zappa

[[email protected]]

Hi,

Thank you so much everyone for your input. I really appreciate it. It
is strange that some people are writing about me wanting to sacrifice
the quality of music, and I'm sure they think they can here all kinds
of diferences in amplifiers, which sounds like magic to me, but that's
just my opinion. I prefered the Technics since it has a remote
control, plus this amplifier worked like a tank so far, and all this
live gear I'm sure is very solid and nice, but I need something for my
home, not rehearsal room, something with a remote control and
something that would nicely fit my Dynaudio BM15 (later on I'll think
about adding a subwoofer to the setup). Until recently I thought there
is no way that I can find something for a decent price (not costing
1000s), but (hurray hurray) I found to contenders, and I would really
appreciate your thoughs on those pieces, it's Onkyo and Yamaha
integrated amps, which don't need pre-amps. My biggest concern is that
Yamaha states it's a 8ohm-6 ohm amplifier, though they rate the
dynamic power at 8/6/4/2 ohms, their specification goes like this:

Yamaha AX-1090

Minimum RMS power per channel
8 ohms, 20hz to 20 khz 0.01 THD - 145W
6 ohms, 20hz to 20 khz 0.02 THD - 185W

Dynamic power per channel
8/6/4/2 ohms - 220 / 290 / 360 / 460W

DIN standart output power per channel
(europe model only)
4 ohms, 1khz 0.7 thd - 250W

Dynamic headroom
8/6 ohms - 1.81 db / 1.95 db
IEC power (8 ohms, 1 khz 0.01 THD
(europe model only) 170W

Power band width
8 ohms, 72.5W 0.03 THD

Damping factor
8 ohms 20 hz to 20 khz 350 or more


The other contender is an Onkyo A-9755, which is 8-4 ohms amp, but on
the pricey side for me:

Power output: 150 W + 150 W (8 Ù, 1 kHz, DIN)
300 W + 300 W (4 Ù, 1 kHz, JEITA)
Dynamic power: 330 W + 330 W (3 Ù, Front)
270 W + 270 W (4 Ù, Front)
170 W + 170W (8 Ù, Front)
THD (total harmonic distortion): 0.08 % (1 kHz, 1 W)
Damping factor: 25 (Front, 1 kHz, 8 Ù)
Input sensitivity and impedance: 200 mV, 50 kÙ (CD)
2.5 mV, 50 kÙ (PHONO MM)
Output level and impedance: 200 mV, 2.2 kÙ (REC OUT)
Phono overload: 70 mV (MM, 1 kHz, 0.5 %)
Frequency response: 10 Hz-60 kHz, +1 dB-3 dB (CD)
Tone control: +10 dB, -10 dB, 100 Hz (BASS)
+10 dB, -10 dB, 20 kHz (TREBLE)
+10 dB, 50 Hz (LOUDNESS)
+2 dB, 10 kHz (LOUDNESS)
SN ratio: 100 dB (CD, IHF-A)
70 dB (PHONO, IHF-A)
Speaker impedance: 4-16 Ù

These are my speakers: Dynaudio BM15 passives:
Frequency Response
(+/- 3 dB) 43 Hz - 20 kHz
Peak SPL 1m, pair
(IEC Long Term) 127 dB Peak
Peak SPL 2m, 5.1
(IEC Long Term) 128,5 dB Peak
Max SPL 1m
SPL @ 1m (+4/-10) 109 dB RMS
Amplifier Minimum 50 W ( 94 dB SPL @ 2m)
IEC Long term powerhandling 250W
IEC Short term powerhandling 1000W
Sensitivity 88 dB
Impedance Nominal 4 ohm
Impedance HF (200 kHz) 5,9 ohm
Resonance Frequency 43 Hz
Internal Cabinet Volume 25,8 liters
Bass Principle Bass reflex
Crossover Frequencies 2700 Hz
Crossover Slope Woofer 6 dB/oct; Tweeter 12 dB/oct

I know that Onkyo is 4 ohms, so it's more fitting to my speakers, but
as I said it's a bit on the pricey side, plus it wouldn't hurt to
understand (for me) is there any difference in those specs (except for
the obvious power difference in wattage).

Thanks so much in advance!

Ray