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post #31 of 57 Old 05-12-2012, 09:07 AM
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So almost any brand name solid state amplifier will handle the speaker identically, especially the varying resistance levels of the speaker.
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post #32 of 57 Old 05-13-2012, 02:28 PM
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Originally Posted by chikoo View Post

Prove it that what i said is irrelevant. Just knowing how many fallacies out there does not make you the smart intelligent one.

You don't have to get so personal. Your statement was answered in post 24 which AFAIK you have not responded to.
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post #33 of 57 Old 05-13-2012, 08:08 PM
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I get all the discussion about amps sounding the same, and for the most part, I agree. In general, I think Dennis Erskine nails it when he says that amps should not be "tone controls." However, I'll add the caveat that amps need to remain within their own performance envelope with respect to distortion and clipping.

Therefore, if the OP is hearing "brightness", it begs the question: Is he using his amp within its' performance envelope? Let's look at the amps in the Sony STR DH820:

Quote:


Output Power

(8Ohms 1kHz) THD : 1%
(8Ohms 20-20kHz) THD : 0.09%
8Ohms 1kHz : 110W+110W
8Ohms 20-20kHz : 100W + 100W

Output Power (JEITA 10%)/ Rated Output Power(0.09% 20Hz-20kHz 4Ohm) : 10%
Output Power (JEITA 10%)/Rated Output Power(0.09% 20Hz-20kHz 8Ohm) : 150W
Total : 945W (135W/ch x 7 (8?, 1kHz, 0.05% THD))

Amplifier Features

4 Ohm/8 Ohm Switching : 8 Ohm only
Advanced Auto Volume : Yes
Analog Direct : Yes
Bi-AMP : Yes
Digital Legato Linear : Yes
Number of amp. channels : 7ch (Sub must be self powered)
Sound Optimizer : Yes
Speaker Selector : A/B/ A+B
Speaker Terminal : Screw
Sub Woofer X' Over : 17 points (40-200Hz)

http://store.sony.com/webapp/wcs/sto...specifications

So, we have an amp that is specified for 8 Ohm loads, (i.e., can't deliver enough current to drive 4 Ohm loads), and a power supply that causes the spec's to change depending on the frequency(s) driven, (i.e., 110 watts @1 Khz, 100 watts 20Hz - 20kHz, which is another indication of a marginally inadequate power supply.)

Now, let's look at the speakers:

Quote:


Aviano 6

Specifications

Drive units (1) 1" aluminium dome tweeter
(2) 6.5" CPC aluminium mid/bass
Frequency response 38Hz - 22kHz
Sensitivity 88dB
Nominal impedance 4 - 8 Ohms
Crossover Damped 2nd order with DVP
Recommended amplifier power 15-150 Watts
Magnetically shielded within 50mm of cabinet
Weight 17.3kg (38.1lbs)
Dimensions (h x w x d) 950 x 205 x 298mm
38 x 8.2 x 11.9"
Available Finishes Dark Walnut, Black

http://www.mordaunt-short.com/products/aviano-6

(Actually, it's much worse than that: S&V measured the speaker at 3.3 to 6 Ohms with a sensitivity of 83 dB): http://www.soundandvisionmag.com/art...ystem?page=0,2

So, we now have a low impedance speaker, with low sensitivity, being driven by an amp not capable of driving low impedance speakers and with a limited current delivery capability. That sounds (PI) like a recipe for clipping, compression and distortion.

Something else the OP says plays into this:

Quote:


...but it just sounds to bright and not punchie enough on 2 channel stereo. dd sounds fine tho with the sub running.

Most ported speakers show an impedance dip just above the port tune, which in this case is about 35 Hz. If he uses the sub with DD, (and sets a typical crossover of 80 Hz), he eliminates, (or more correctly, greatly reduces), the impact of the impedance dip, AND he reduces the power demands on the amps significantly. This would reduce the clipping, compression and distortion significantly. Hence why "dd sounds fine tho with the sub running."

Bottom line, IMO, the "brightness" and "lack of punchiness" he's hearing is probably the amps clipping. He's not using the right amps for his low impedance, power hungry speakers, and he probably *would* benefit from an amplifier upgrade. Unfortunately, his Sony receiver doesn't seem to have preamp outputs, so he would have no way to upgrade the amp section, short of getting a new receiver.

garthvader86, if you decide to upgrade your receiver, look for a receiver capable of driving low impedance loads. In the Amplifier Specifications, look for a spec for power delivery into 4 Ohm loads. If there is no such spec, the receiver can't drive 4 Ohm speakers. The ideal spec would be a doubling of the 8 Ohm spec, but don't expect to find that. However look for at least a 50% wattage increase into 4 Ohms over the 8 Ohm spec.

Good luck.

Craig

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post #34 of 57 Old 05-14-2012, 12:51 AM - Thread Starter
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Hi Craig thanks for the informative reply,could you suggest any amps that have this ability without braking the bank? the speakers are sounding a lot better but like people have said I don't think I'm getting there full potential.

Quality is in the ear of the beholder (but a little knowledge helps)
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post #35 of 57 Old 05-14-2012, 03:54 AM
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Quote:
Originally Posted by craig john View Post

I get all the discussion about amps sounding the same, and for the most part, I agree. In general, I think Dennis Erskine nails it when he says that amps should not be "tone controls." However, I'll add the caveat that amps need to remain within their own performance envelope with respect to distortion and clipping.

Therefore, if the OP is hearing "brightness", it begs the question: Is he using his amp within its' performance envelope? Let's look at the amps in the Sony STR DH820:


http://store.sony.com/webapp/wcs/sto...specifications

So, we have an amp that is specified for 8 Ohm loads, (i.e., can't deliver enough current to drive 4 Ohm loads), and a power supply that causes the spec's to change depending on the frequency(s) driven, (i.e., 110 watts @1 Khz, 100 watts 20Hz - 20kHz, which is another indication of a marginally inadequate power supply.)

The idea that an amp with that particular set of ratings indicate that "can't deliver enough current to drive 4 Ohm loads" is not necessarily true. I base this statement on personally bench testing over 100 different power amps and receivers over the years.


It appears that the cited "Output Power (JEITA 10%)/ Rated Output Power(0.09% 20Hz-20kHz 4Ohm) : 10%" is a typographic error that afflicts the Sony web site pages for this particularl line of products. JEITA power is supposed to be given in watts, not percent. Therefore this information should be disregarded. This leaves us with no evidence at all to judge its performance at 4 ohms.

In the real world virtually every power amp's actual performance depends on the frequency it is driven with. This is even true of amps with 5 figure prices, that weigh like 100 pounds, that have upwards of 50 output transistors, and that have massive toroidal power transformers.

An amp's power output also depends on how you specify distortion. A modern SS power amp with 10% THD or 1% THD or even 0.1% THD is almost always clipping. Drop the power output by say 10%, it stops clipping, and the THD is orders of magnitude less. It is the non-clipping performance that is more generally representative of how the amplifier sounds.

Finally, an amp's distortion may depend on how its loaded. Lower impedance loads generally increase distortion. However, this effect has limits as long as you stay out of clipping. If a power amp's distortion doubles when the impedance is cut in half, then it may be less linear with lower impedance loads. If a power amp's distortion increases more dramaticaly when the impedance is cut in half, then it is probably clipping, and lower distortion operation could easily come with a nominal (10% more or less) decrease in power output.


Specification sheets are designed by marketing departments, or engineers that are highly influenced by how something looks on paper. They are often very meager sources of reliable information about how things sound.
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post #36 of 57 Old 05-14-2012, 03:55 AM
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Quote:
Originally Posted by garthvader86 View Post

Hi Craig thanks for the informative reply,could you suggest any amps that have this ability without braking the bank? the speakers are sounding a lot better but like people have said I don't think I'm getting there full potential.

Unfortunately it appears that Craig is taking a spec sheet with an obvious typographic error well outside of its logical range of application.
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post #37 of 57 Old 05-14-2012, 05:59 PM
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Quote:
Originally Posted by chikoo View Post

So almost any brand name solid state amplifier will handle the speaker identically, especially the varying resistance levels of the speaker.

Umm... This was supposed to be a question. Forgot the question mark
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post #38 of 57 Old 05-14-2012, 07:30 PM
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Quote:
Originally Posted by arnyk View Post

The idea that an amp with that particular set of ratings indicate that "can't deliver enough current to drive 4 Ohm loads" is not necessarily true. I base this statement on personally bench testing over 100 different power amps and receivers over the years.


It appears that the cited "Output Power (JEITA 10%)/ Rated Output Power(0.09% 20Hz-20kHz 4Ohm) : 10%" is a typographic error that afflicts the Sony web site pages for this particularl line of products. JEITA power is supposed to be given in watts, not percent. Therefore this information should be disregarded. This leaves us with no evidence at all to judge its performance at 4 ohms.

In the real world virtually every power amp's actual performance depends on the frequency it is driven with. This is even true of amps with 5 figure prices, that weigh like 100 pounds, that have upwards of 50 output transistors, and that have massive toroidal power transformers.

An amp's power output also depends on how you specify distortion. A modern SS power amp with 10% THD or 1% THD or even 0.1% THD is almost always clipping. Drop the power output by say 10%, it stops clipping, and the THD is orders of magnitude less. It is the non-clipping performance that is more generally representative of how the amplifier sounds.

Finally, an amp's distortion may depend on how its loaded. Lower impedance loads generally increase distortion. However, this effect has limits as long as you stay out of clipping. If a power amp's distortion doubles when the impedance is cut in half, then it may be less linear with lower impedance loads. If a power amp's distortion increases more dramaticaly when the impedance is cut in half, then it is probably clipping, and lower distortion operation could easily come with a nominal (10% more or less) decrease in power output.


Specification sheets are designed by marketing departments, or engineers that are highly influenced by how something looks on paper. They are often very meager sources of reliable information about how things sound.

OK, ignoring the "marketing spec sheet" for a moment, let's look at the spec's documented in the actual Sony's user's manual for the STR-DH820:

Quote:


USA model1)
Minimum RMS Output Power
(8 ohms, 20 Hz - 20 kHz, THD 0.09%)
100 W + 100 W
Stereo Mode Output Power
(8 ohms, 1 kHz, THD 1%)
110 W + 110 W
Surround Mode Output Power2)
(8 ohms, 1 kHz, THD 10%)
150 W per channel

Page 83 from the manual found here"
http://esupport.sony.com/US/p/model-...ls#/manualsTab

So.... when you limit the frequency range from "full range" (20 Hz - 20 kHz) to a single frequency, (1 kHz),... AND you raise the distortion tolerance from less than 1/10 of 1%, (0.09%) to over 10x as much, (a full 1%),... and the power output only goes up by 10 dB, from 100 to 110 dB, what does that say about the current delivery capability of the amp???

Add to that the fact that Sony doesn't even specify an output into anything less than 8 Ohms.... I'm sorry, but these are just not very robust amps, and IMO, they should be used with significant caution when driving more *difficult* speaker loads.

To address that point: The Mondurant-Short speakers are very insensitive @ 83 dB/1 watt/1 meter, non-anechoic. Add to that the additional current drain these speakers expose the amplifiers to with their low nominal impedance of 3.6 to 6 Ohms, and the significant "load" the amplifier "sees" is quite formidable.

So, Arny, are you saying it's OK to run an 83 dB sensitivity, low impedance, (3.6 to 6 Ohm), speaker with an amp rated at 100 wpc into 8 Ohms, and no rated power output at any lower impedance?

Although we don't know the room size, the speaker/listening position, the listening distance, or the listener's SPL requirements, I would still be embarrassed to recommend such a setup, (unless the listener is not looking for anything more than "modest" (<95 dB), listening levels in a "small" room.) At anything above "modest" levels, I would expect excessive heat generation in the amp, compression, distortion, clipping, and at higher levels, amplifier thermal shutdown... hopefully *before* the tweeters blow.

If I personally owned these M-S speakers, and I had a more normally sized listening space and listening distance, and I wanted more "spirited" SPL's, I would want at least several hundred watts of amplification, as well as the ability to drive low impedance loads. Short of that, I would expect significant amplifier "limitations."

Am I missing something?

Craig

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Perfection is not attainable, but if we chase perfection we can catch excellence."

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post #39 of 57 Old 05-15-2012, 10:43 AM - Thread Starter
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Right guys can some one clear this up for me as I don't really understand what it all means( o 160 W/Ch at 6 ?, 1 kHz, 1%, 1 Channel Driven)I'm gonna get a new avr as I'm paranoid that I'm gonna damage my speakers with my current setup the avr in question is a onkyo TX-NR609.

Quality is in the ear of the beholder (but a little knowledge helps)
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post #40 of 57 Old 05-15-2012, 11:03 AM
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Quote:
Originally Posted by arnyk View Post

The idea that an amp with that particular set of ratings indicate that "can't deliver enough current to drive 4 Ohm loads" is not necessarily true. I base this statement on personally bench testing over 100 different power amps and receivers over the years.


It appears that the cited "Output Power (JEITA 10%)/ Rated Output Power(0.09% 20Hz-20kHz 4Ohm) : 10%" is a typographic error that afflicts the Sony web site pages for this particularl line of products. JEITA power is supposed to be given in watts, not percent. Therefore this information should be disregarded. This leaves us with no evidence at all to judge its performance at 4 ohms.

In the real world virtually every power amp's actual performance depends on the frequency it is driven with. This is even true of amps with 5 figure prices, that weigh like 100 pounds, that have upwards of 50 output transistors, and that have massive toroidal power transformers.

An amp's power output also depends on how you specify distortion. A modern SS power amp with 10% THD or 1% THD or even 0.1% THD is almost always clipping. Drop the power output by say 10%, it stops clipping, and the THD is orders of magnitude less. It is the non-clipping performance that is more generally representative of how the amplifier sounds.

Finally, an amp's distortion may depend on how its loaded. Lower impedance loads generally increase distortion. However, this effect has limits as long as you stay out of clipping. If a power amp's distortion doubles when the impedance is cut in half, then it may be less linear with lower impedance loads. If a power amp's distortion increases more dramaticaly when the impedance is cut in half, then it is probably clipping, and lower distortion operation could easily come with a nominal (10% more or less) decrease in power output.


Specification sheets are designed by marketing departments, or engineers that are highly influenced by how something looks on paper. They are often very meager sources of reliable information about how things sound.




Sony "clearly" notes the speaker impendance range that can be used with their AVRs. 8-16 Ohms is the impedance range as noted on the rear of the AVR in question.

From the instruction manual:


LL
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post #41 of 57 Old 05-15-2012, 12:02 PM
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Quote:
Originally Posted by J_Palmer_Cass View Post

Sony "clearly" notes the speaker impendance range that can be used with their AVRs. 8-16 Ohms is the impedance range as noted on the rear of the AVR in question.

It could be a problem, or it could be the common situation where the amp can drive music which is varying and impulsive into lower impedance speakers, because the music keeps changing, and so does the speaker's effective impedance.

The cautions about 4 ohm loads usually only actually refer to test bench operation with continuous tones.

There are so many 4 ohm speakers and speakers that go even lower than 4 ohms (like 3.0 or 3.5 ohms) that its hard for me to imagine that anybody would completely ignore them. Of course Sony is losing money like there's no tomorrow, so what used to be totally sure may not be so sure any more. :-(

For their sake, I hope that Sony isn't building stupid amps.

The other thing to remember is that the power drain on an amp for 4 ohm loads and less-than-rated power is the same as it is for 8 ohm loads @ rated power. Since few ever run their amps near clipping or even rated power, still not so much of a problem.
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post #42 of 57 Old 05-15-2012, 12:35 PM
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Quote:
Originally Posted by garthvader86 View Post

Right guys can some one clear this up for me as I don't really understand what it all means( o 160 W/Ch at 6 ?, 1 kHz, 1%, 1 Channel Driven)I'm gonna get a new avr as I'm paranoid that I'm gonna damage my speakers with my current setup the avr in question is a onkyo TX-NR609.

How big is your room? Is it sealed or open to other spaces?

How far do you sit from your speakers?

How far are the speakers from the walls?

How loud do you like to listen?

Are you willing to use your subwoofer when you listen to 2-channel?

What is your budget?

Use this calculator to get you into the ballpark of how much wattage you need to reach the levels you desire:
http://myhometheater.homestead.com/splcalculator.html

Craig

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Perfection is not attainable, but if we chase perfection we can catch excellence."

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post #43 of 57 Old 05-15-2012, 12:51 PM
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Quote:
Originally Posted by garthvader86 View Post

Hi Craig thanks for the informative reply,could you suggest any amps that have this ability without braking the bank? the speakers are sounding a lot better but like people have said I don't think I'm getting there full potential.


Instead of running in the 2 channel mode (no subwoofer no crossovers), try the auto select mode. That will allow you to run in the 2.1 mode. Go into the crossover menu, and check the crossover frequency. If the R & L mains are crossed at 80 Hz, try 40 Hz and work your way up.
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post #44 of 57 Old 05-15-2012, 12:58 PM
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Quote:
Originally Posted by arnyk View Post

It could be a problem, or it could be the common situation where the amp can drive music which is varying and impulsive into lower impedance speakers, because the music keeps changing, and so does the speaker's effective impedance.

The cautions about 4 ohm loads usually only actually refer to test bench operation with continuous tones.

There are so many 4 ohm speakers and speakers that go even lower than 4 ohms (like 3.0 or 3.5 ohms) that its hard for me to imagine that anybody would completely ignore them. Of course Sony is losing money like there's no tomorrow, so what used to be totally sure may not be so sure any more. :-(

For their sake, I hope that Sony isn't building stupid amps.

The other thing to remember is that the power drain on an amp for 4 ohm loads and less-than-rated power is the same as it is for 8 ohm loads @ rated power. Since few ever run their amps near clipping or even rated power, still not so much of a problem.


Sony AVR's in the modest price range have been stamped 8 - 16 ohms for at least a decade. They will not drive 4 ohm loads "properly", at least when the mains are set to large.

Driving the typical 2 way 8 ohm speaker will be no problem for those AVRs.
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post #45 of 57 Old 05-16-2012, 03:41 AM
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Quote:
Originally Posted by J_Palmer_Cass View Post

Sony AVR's in the modest price range have been stamped 8 - 16 ohms for at least a decade. They will not drive 4 ohm loads "properly", at least when the mains are set to large.

I been looking for an actual technical test that sheds light on this claim.

Gotcha! ;-)

First, this is a typical Sony receiver, a STR-DH520, a bottom of their line sub-$200 street price unit with only 8 ohm ratings:

"http://store.sony.com/wcsstore/SonyStyleStorefrontAssetStore/pdf/warranty/SEL-asset-248878.pdf

"Amplifier section USA model

Minimum RMS Output Power (8 ohms, 20 Hz – 20 kHz, THD 0.09%)
90 W + 90 W

Stereo Mode Output Power (8 ohms, 1 kHz, THD 1%)
100 W + 100 W

Surround Mode Output Power (8 ohms, 1 kHz, THD 10%)
130 W per channel
"

There are no 4 ohm ratings on this receiver's specification page. None.

Now for what happens when the rubber hits the road - actual performance:

http://www.hometheater.com/content/s...-labs-measures

"This graph shows that the STR-DH520's left channel, from CD input to speaker output with two channels driving 8-ohm loads, reaches 0.1% distortion at 114.8 watts and 1% distortion at 141.7 watts. Into 4 ohms, the amplifier reaches 0.1% distortion at 133.6 watts and 1% distortion at 160.6 watts."

Clearly this cheap Sony receiver is capable of delivering substantial reasonably clean power (> 100 watts @ < 0.1% THD) to 4 ohm loads.

Moving up this Sony line, we find the STR-DN1020 at nearly three times the street price:

I have confirmed that the back of this receiver has the following text printed below its speaker output terminals:

http://www.docs.sony.com/release/STRDN1020.pdf

Example P 23.

"Speakers, Use 8-16 ohm".

http://www.hometheater.com/content/s...-labs-measures

"This graph shows that the STR-DN1020’s left channel, from CD input to speaker output with two channels driving 8-ohm loads, reaches 0.1 percent distortion at 115.1 watts and 1 percent distortion at 133.4 watts. Into 4 ohms, the amplifier reaches 0.1 percent distortion at 144.0 watts and 1 percent distortion at 169.6 watts."

Again, > 100 clean watts are delivered into 4 ohm loads.

I also confirmed this for a Sony ES-line receiver.

http://www.hometheater.com/content/s...-labs-measures

"This graph shows that the STR-DA4600ES’s left channel, from CD input to speaker output with two channels driving 8-ohm loads, reaches 0.1 percent distortion at 122.3 watts and 1 percent distortion at 155.3 watts. Into 4 ohms, the amplifier reaches 0.1 percent distortion at 158.2 watts and 1 percent distortion at 224.2 watts."

Game, set match! ;-)

I think it is safe to say that if the bottom of the line and the top of line have appreciable power @4 ohms, so does the rest of the line.
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post #46 of 57 Old 05-16-2012, 06:42 AM
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And here is the Sony STR-DA4600ES A/V Receiver, (MSRP $1,499), measured by Sound and Vision:



Quote:


Output at clipping (1 kHz into 8/4 ohms)
1 channel driven: 157/242 W (22.0/23.8 dBW)
5 channels driven (8 ohms): 65 W (18.1 dBW)
7 channels driven (8 ohms): ~20 W (13.0 dBW)*
*Restricted by protection circuitry when 6 or more channels driven

STEREO PERFORMANCE, DIGITAL INPUT
Reference level is -20 dBFS; all level trims at 0. Volume setting for reference level was 0.

Output at clipping (1 kHz, 8/4 ohms, both channels driven): 133/199 W (21.2/23.0 dBW)

http://www.soundandvisionmag.com/art...eiver?page=0,3

IOW, the power supply is fine driving ONE or TWO channels at 8 Ohms, but it's current limited when driving multiple channels. They didn't even measure the multichannel output at 4 Ohms.

Using the calculator I previously linked, (which I admit is only a basic guideline), shows that 199 watts with (2) 83 dB sensitivity speakers at 12 ft. yields about 98 dB with no headroom. Using 5 speakers and 65 watts, yields 97 dB. IOW, Full Reference Level is not possible with this receiver and these speakers. In fact, to be safe, it should never be run higher than about 10 dB below RL. And this is Sony's TOL, $1,500 receiver. I can't imagine the power supply in their $400 receiver is as robust.

I still say that I would not use this Sony STR DH820 receiver to drive 83 dB sensitivity, lower impedance speakers. If I did use this receiver to drive these Mondurant-Short speakers, I would *only* do so with Bass Management with an 80 Hz crossover engaged at all times, and I would be very cautious with the Master Volume Control.

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post #47 of 57 Old 05-16-2012, 07:03 AM
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Quote:
Originally Posted by craig john View Post

And here is the Sony STR-DA4600ES A/V Receiver, (MSRP $1,499), measured by Sound and Vision:




http://www.soundandvisionmag.com/art...eiver?page=0,3

IOW, the power supply is fine driving ONE or TWO channels at 8 Ohms, but it's current limited when driving multiple channels. They didn't even measure the multichannel output at 4 Ohms.

So what?

One problem with your comment is that you are equating a bench test with a resistive load and a steady sine wave signal at specified power with someone listening to music using a loudspeaker.

I've been bench testing audio gear almost as long as I've been using it. I did my first bench test of a piece of audio gear in or before 1960. I currently own more test equipment related power amps to and have it at my full disposal right here in my house. Two operational Audio Precision test sets in my workroom, for example. Not only that but I have serious chops when it comes to doing listening tests. I invented ABX.

So here's the deal. Maybe a decade ago a well-known magazine writer brought about 10 varied power amps over to my house for testing. For example, 2 or 3 were Brystons.

I had a new computer-assisted procedure for testing power amps that required almost zero investment in test equipment. It was all about Volksmeasuring. My tests were centerpieced by a loudspeaker simulator that was about as tough of a load as a speaker can present to an amplifier and still claim to be a reasonable design. It is about twice as tough as any used by any magazine that prides itself about such things.

It didn't take to long to see that the tests with resistive loads as always, caused a lot of stress on the power amps. But, the ones into a the toughest loudspeaker like load likely to show up in any audiophile's life and still relate to a mainstream or credibly designed high end speaker was a cakewalk in comparison.

If we added to that, when we used signals that had frequency and varying amplitude content like music, the stress on the power amps was so slight that it almost seemed like they would run with their power cords cut. Well, not quite but it makes the point.

The bottom line is that you're never going to put any significant stress on a receiver that is even a fraction of the tests you cited, as long as you:

(1) Use speakers that were professionally designed and weren't designed by a madman or a rank amateur.

(2) Listen to music, even highly clipped CD tracks, but somethng that sounds something like music. IOW not sine waves, but even regular pink or white noise would be OK.

(3) And keep peak levels in all channels lower than the 2-channel power rating for the receiver.

So, does the scare story painted above relate to someone asking about bad sound of their system on AVS? Nope.
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post #48 of 57 Old 05-16-2012, 07:55 AM
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Quote:
Originally Posted by arnyk View Post

So what?

One problem with your comment is that you are equating a bench test with a resistive load and a steady sine wave signal at specified power with someone listening to music using a loudspeaker.

I've been bench testing audio gear almost as long as I've been using it. I did my first bench test of a piece of audio gear in or before 1960. I currently own more test equipment related power amps to and have it at my full disposal right here in my house. Two operational Audio Precision test sets in my workroom, for example. Not only that but I have serious chops when it comes to doing listening tests. I invented ABX.

Wow. And you play tennis too?

Quote:
Originally Posted by arnyk View Post

So here's the deal. Maybe a decade ago a well-known magazine writer brought about 10 varied power amps over to my house for testing. For example, 2 or 3 were Brystons.

I had a new computer-assisted procedure for testing power amps that required almost zero investment in test equipment. It was all about Volksmeasuring. My tests were centerpieced by a loudspeaker simulator that was about as tough of a load as a speaker can present to an amplifier and still claim to be a reasonable design. It is about twice as tough as any used by any magazine that prides itself about such things.

It didn't take to long to see that the tests with resistive loads as always, caused a lot of stress on the power amps. But, the ones into a the toughest loudspeaker like load likely to show up in any audiophile's life and still relate to a mainstream or credibly designed high end speaker was a cakewalk in comparison.

If we added to that, when we used signals that had frequency and varying amplitude content like music, the stress on the power amps was so slight that it almost seemed like they would run with their power cords cut. Well, not quite but it makes the point.

The bottom line is that you're never going to put any significant stress on a receiver that is even a fraction of the tests you cited, as long as you:

(1) Use speakers that were professionally designed and weren't designed by a madman or a rank amateur.

(2) Listen to music, even highly clipped CD tracks, but somethng that sounds something like music. IOW not sine waves, but even regular pink or white noise would be OK.

(3) And keep peak levels in all channels lower than the 2-channel power rating for the receiver.

So, does the scare story painted above relate to someone asking about bad sound of their system on AVS? Nope.

Whatever, Dude. I still would not pair that receiver with those speakers. But hey, you invented ABX so, "Game, Set, Match" to you buddy.

Craig

Lombardi said it:
Perfection is not attainable, but if we chase perfection we can catch excellence."

My System

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post #49 of 57 Old 05-16-2012, 09:45 AM
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Quote:
Originally Posted by arnyk View Post

I been looking for an actual technical test that sheds light on this claim.

Gotcha! ;-)

First, this is a typical Sony receiver, a STR-DH520, a bottom of their line sub-$200 street price unit with only 8 ohm ratings:

"http://store.sony.com/wcsstore/SonyStyleStorefrontAssetStore/pdf/warranty/SEL-asset-248878.pdf

"Amplifier section USA model

Minimum RMS Output Power (8 ohms, 20 Hz – 20 kHz, THD 0.09%)
90 W + 90 W

Stereo Mode Output Power (8 ohms, 1 kHz, THD 1%)
100 W + 100 W

Surround Mode Output Power (8 ohms, 1 kHz, THD 10%)
130 W per channel
"

There are no 4 ohm ratings on this receiver's specification page. None.

Now for what happens when the rubber hits the road - actual performance:

http://www.hometheater.com/content/s...-labs-measures

"This graph shows that the STR-DH520's left channel, from CD input to speaker output with two channels driving 8-ohm loads, reaches 0.1% distortion at 114.8 watts and 1% distortion at 141.7 watts. Into 4 ohms, the amplifier reaches 0.1% distortion at 133.6 watts and 1% distortion at 160.6 watts."

Clearly this cheap Sony receiver is capable of delivering substantial reasonably clean power (> 100 watts @ < 0.1% THD) to 4 ohm loads.

Moving up this Sony line, we find the STR-DN1020 at nearly three times the street price:

I have confirmed that the back of this receiver has the following text printed below its speaker output terminals:

http://www.docs.sony.com/release/STRDN1020.pdf

Example P 23.

"Speakers, Use 8-16 ohm".

http://www.hometheater.com/content/s...-labs-measures

"This graph shows that the STR-DN1020’s left channel, from CD input to speaker output with two channels driving 8-ohm loads, reaches 0.1 percent distortion at 115.1 watts and 1 percent distortion at 133.4 watts. Into 4 ohms, the amplifier reaches 0.1 percent distortion at 144.0 watts and 1 percent distortion at 169.6 watts."

Again, > 100 clean watts are delivered into 4 ohm loads.

I also confirmed this for a Sony ES-line receiver.

http://www.hometheater.com/content/s...-labs-measures

"This graph shows that the STR-DA4600ES’s left channel, from CD input to speaker output with two channels driving 8-ohm loads, reaches 0.1 percent distortion at 122.3 watts and 1 percent distortion at 155.3 watts. Into 4 ohms, the amplifier reaches 0.1 percent distortion at 158.2 watts and 1 percent distortion at 224.2 watts."

Game, set match! ;-)

I think it is safe to say that if the bottom of the line and the top of line have appreciable power @4 ohms, so does the rest of the line.



Silly child!

I performed an operational test of two Sony AVRs with the same pair of speakers.

Sony STR-DE985

Sony STR-DA4ES

NHT 2.9 speakers

The STR DE-985 did not have enough current capability to drive those NHT speakers properly. The only way to get the NHT 2.9 speakers to sound proper with the DE-985 was to do a passive bi-amp setup via an external "subwoofer" amplifier.


The review of the speakers showed a similar outcome:

"The NHT's impedance (fig.1) stays between 4 and 6 ohms over much of the audioband, with a dip to 3.4 ohms at 54Hz but a moderately low phase angle overall. The combination of 6 ohms magnitude and 45 degrees phase angle at 40Hz might be too demanding for some receivers, but an amplifier rated into 4 ohms would be a good match for the speaker. My estimate of the 2.9's voltage sensitivity came in marginally higher than spec at 88dB/2.83V/m, meaning that even a 50W amplifier will drive it to quite high levels in a moderate-sized room."


http://www.stereophile.com/content/n...r-measurements



Game, set and match with real world trial!
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post #50 of 57 Old 05-16-2012, 01:44 PM
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Quote:
Originally Posted by J_Palmer_Cass View Post

Silly child!

I performed an operational test of two Sony AVRs with the same pair of speakers.

Sony STR-DE985

Sony STR-DA4ES

NHT 2.9 speakers

The STR DE-985 did not have enough current capability to drive those NHT speakers properly. The only way to get the NHT 2.9 speakers to sound proper with the DE-985 was to do a passive bi-amp setup via an external "subwoofer" amplifier.

The above looks to me like opinion stated as fact. No objective criteria stated, none applied, no indication of pass or fail by any means other than personal opinion. No indication of test signal, no indication of desired performance levels, no indication of kind of technical failure.
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post #51 of 57 Old 10-24-2012, 07:35 PM
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I bought the STR-DN1020 on special 4 months ago. In the history of buying receivers for 32 years, this is the worst garbage for playing 2 channel music. I have thin bass, almost no kickdrum punch. This is flat. I can go to +10db bass and it doesn't sound natural. Lots of mids and highs though. They forgot the bass amplifier, assuming were are buying subs. I refuse to. So let me raise the bass, lower the mids, and highs but there is no mid EQ. Same speakers pound my chest on a 20 watt 1990 HK3300. Flat! Even using sound optimizer (loudness) doesn't solve the lack of punch. Absolute garbage. When I started dj'ing in the early 80's at home, i had SL1200 Mk2, Shure Sc35C carts and a Yamaha PM430 mixer with vinyl. Outputted to an old receiver with 2 custom built monitors, non engineered box with 8" woofers and piezos and I could hear bass and mix with flat EQ's. If I would use this receiver, I would not be able to mix. My friend has an Onkyo AVR with dual 8" towers and he has no bass. Anyways i bought it for my STB and DVD/Bluray and that's all it's good for.
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post #52 of 57 Old 10-25-2012, 09:26 AM
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Quote:
Originally Posted by chikoo View Post


Umm... This was supposed to be a question. Forgot the question mark

Umm...if you don't know the difference between resistance and impedance, perhaps you should back out of the thread...it's way over your head.
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post #53 of 57 Old 10-25-2012, 02:26 PM
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Ummmm, if you had nothing to say 5 months ago, why is it important for you to "break chops" now? rolleyes.gif
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post #54 of 57 Old 10-26-2012, 04:19 AM
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I see that once again, you have nothing to add....just upping your post count wink.gif
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post #55 of 57 Old 10-26-2012, 06:11 AM
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Quote:
Originally Posted by wz1 View Post

I bought the STR-DN1020 on special 4 months ago. In the history of buying receivers for 32 years, this is the worst garbage for playing 2 channel music. I have thin bass, almost no kickdrum punch. This is flat. I can go to +10db bass and it doesn't sound natural. Lots of mids and highs though. They forgot the bass amplifier, assuming were are buying subs.

Show me a receiver with a built-in subwoofer power amp, and you will show me something that is almost as hard to find as hen's teeth.

Demanding deep throbbing bass from small speakers without a sub is like expecting a car to drive without putting in any gasoline. ;-)
Quote:
I refuse to.

Well, if you want to fight the whole audio industry, then your chances of prevailing are pretty minimal.

Quote:
So let me raise the bass, lower the mids, and highs but there is no mid EQ. Same speakers pound my chest on a 20 watt 1990 HK3300. Flat! Even using sound optimizer (loudness) doesn't solve the lack of punch.

It appears that this receiver has a far more sophisticated facility than just tone controls or a loudness contour switch - "Digital Cinema Auto Calibration" . How does it wotk?

Quote:
Absolute garbage. When I started dj'ing in the early 80's at home, i had SL1200 Mk2, Shure Sc35C carts and a Yamaha PM430 mixer with vinyl. Outputted to an old receiver with 2 custom built monitors, non engineered box with 8" woofers and piezos and I could hear bass and mix with flat EQ's.

So how do your old speakers work with the Sony?

If you don't know, its not a fair comparison.

Quote:
If I would use this receiver, I would not be able to mix.

How so? Are you saying that you can't hook a mixer to it? Why?

Quote:
My friend has an Onkyo AVR with dual 8" towers and he has no bass.

Probably no sub, just like you! ;-)
Quote:
Anyways i bought it for my STB and DVD/Bluray and that's all it's good for.

I sense that old habits and prejudices just aren't working for you any more.

With this modern equipment, you sometimes have to also modernize your thinking...
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post #56 of 57 Old 10-26-2012, 12:49 PM
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Don't need a sub and probably that's why Sony included 2 sub outputs to compensate. My problem is solved by putting back my Pioneer VSX-D509S in the same place with the same speakers. I lose out on HDMI switching though but I am informing myself this time on Pioneer, Denon, or Yamaha products.
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post #57 of 57 Old 05-13-2013, 07:50 AM
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I'm back to say that i was forced to buy a subwoofer after purchasing the STR-DN1020 and not having any bass whatsoever in fullrange mode. I have 2 sets of the same exact bookshelves with 5.5
drivers. One set is with an HK3300 vintage receiver rated at 20 watts/channel. No subwoofer. Sound is fantastic. Other set with the Sony STR-DN1020. Sound is awful and thin. Added a 10" sub with the Sony and sound is still awful. Yesterday I had a breakthrough though. I have to set the crossover point to 120 hz between front/sub for fairly decent sound with fullness.. That means this amplifier is so ****** that it cannot produce bass and it needs all to be offloaded to a sub at 120hz.
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