[[email protected]]

Hi,

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 two
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, and DIN
power at 250W (4ohms) 1 KHz. their specification goes like this (BTW,
yamaha is an old amplifier, from 90's, so any info on it would be
greately appreciated, because I cannot find anything, including the
differences between AX-1050, AX-1070 and AX-1090 amps, the specs of
which look absolutely identical):

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 a bit on the pricey
side for me. Note the low damping factor, which might be a bit of a
problem, is it not? Plus it doesn't have a pre-out, which is weird.
Does this mean I would not be able to connect a subwoofer to it?

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 rated at 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). Which one of these would fit
my speakers better?

Thanks so much in advance!

Ray

[Richard Kuschel]

On Dec 5, 5:58 am, wrote:
Hi,

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 two
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, and DIN
power at 250W (4ohms) 1 KHz. their specification goes like this (BTW,
yamaha is an old amplifier, from 90's, so any info on it would be
greately appreciated, because I cannot find anything, including the
differences between AX-1050, AX-1070 and AX-1090 amps, the specs of
which look absolutely identical):

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 a bit on the pricey
side for me. Note the low damping factor, which might be a bit of a
problem, is it not? Plus it doesn't have a pre-out, which is weird.
Does this mean I would not be able to connect a subwoofer to it?

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 rated at 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). Which one of these would fit
my speakers better?

Thanks so much in advance!

Ray

What are you using the amplifier for? Since this is a Production
newsgroup i would assume that you would be using it with a mixer so
you wouldn't need preamps anyway.

If this for home HiFi application, buy the4 one that sounds best with
your current equipment. You cannot compare sound from a spec sheet.
As to the 4 ohm rating, either of the amplifiers will drive 4 ohm
speakers safely. Unless ou are really cranking the system to high
levels, either will be adequate for sound levels.

[[email protected]]

Thanks, Richard! I'm just not good with all these numbers, that's why
I'm worried. I mean, if the Yamaha amplifier is suitable for 4 ohm
loads, why the hell do they write RMS power in 8 ohms and 6 ohms only?

Thanks again.

Ray

[Scott Dorsey]

wrote:
Thanks, Richard! I'm just not good with all these numbers, that's why
I'm worried. I mean, if the Yamaha amplifier is suitable for 4 ohm
loads, why the hell do they write RMS power in 8 ohms and 6 ohms only?

It's always a good question when hear that kind of thing... odds are
it's because the power at 4 ohms is not twice more than at 8 ohms,
meaning the power supply is petering out.

Still, the power ratings don't really matter... the speakers are pretty
efficient and you won't be using them loud. Worry about what the amps
sound like instead.
--scott

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

[Richard Kuschel]

On Dec 6, 5:48 am, wrote:
Thanks, Richard! I'm just not good with all these numbers, that's why
I'm worried. I mean, if the Yamaha amplifier is suitable for 4 ohm
loads, why the hell do they write RMS power in 8 ohms and 6 ohms only?

Thanks again.

Ray

Check the specs here-- It shows the AX1090 at 2 ohms.

http://www.yamaha.co.jp/english/prod...hf/ax1090.html

[RD Jones]

On Dec 7, 1:01*pm, Richard Kuschel wrote:
On Dec 6, 5:48 am, wrote:

Thanks, Richard! I'm just not good with all these numbers, that's why
I'm worried. I mean, if the Yamaha amplifier is suitable for 4 ohm
loads, why the hell do they write RMS power in 8 ohms and 6 ohms only?

Thanks again.

Ray

Check the specs here-- It shows the AX1090 at 2 ohms.

http://www.yamaha.co.jp/english/prod...hf/ax1090.html

And it has a "speaker impedance selector" ?

rd

[Chris Hornbeck]

On Sun, 7 Dec 2008 21:28:20 -0500, Charlie Olsen
wrote:

And it has a "speaker impedance selector" ?

This is typically a choice of taps on the power transformer's
secondaries to vary supply voltages to the output stages.

As for ratings, maybe the reason they didn't rate at the lower impedance is
because they could not make the frequency response or distortion figures.

FTC preconditioning specs were notoriously dangerous thermally,
requiring long periods at high thermal loads (less than full power
outputs can cause *higher* heat loading - strange but true).

An honest amplifier manufacturer was typically limited more
by FTC protocols than by frequency response or distortion,
in modern-era amplifiers.

All the best fortune,
Chris Hornbeck