Must read....

[klinemj]

Sure looks like that to me...interesting choices of 4 and 6 ohms. Anyone care to share their thoughts on that?

[LCSeminole]

Nov 27, 2010 21:24:49 GMT -5 Lonnie said:

Just a question here, it looks like the amp has an impedance switch on it. Is this correct?

Lonnie, It sure looks like a 4ohm - 6ohm switch. Why does an amplifier need an impedance switch?

[klinemj]

That was exactly what I was wondering! It seems to me like the circuit has to "know" based on Ohm's Law...curious to have one and what it could possibly add!

[geebo]

My old Onkyo receiver had an menu option to select the same impedences. Perhaps when 4 ohm is selected, its cuts the max power available?

[LCSeminole]

I've been researching this amplifier since this thread peaked my interest again in power amplifiers and the difference classes. I haven't found what class this Onkyo power amplifier is, can someone enlighten me. Looking at the picture, the only two I could find with glimpses under the hood, makes me think this has to be quite efficient with only the one heat sink towards the front of the unit. The specs below are from the Onkyo website.




Onkyo PA-MC5500 - THX Ultra 2
AMPLIFIER SECTION:

Power Output -
All Channels 150 W/Ch at 8 ohms;
20 Hz-20 kHz, 0.05%; 2 Channels driven, FTC
Dynamic Power 400 W (3 ohms, Front)
300 W (4 ohms, Front)
180 W (8 ohms, Front)
THD (Total Harmonic Distortion) 0.05 %
(Rated Power)
Damping Factor 60 (Front, 1 kHz, 8 ohms)
Input Sensitivity and Impedance 1 V/47 k-ohms (Balanced)
2 V/22 k-ohms (Unbalanced)
Frequency Response 5 Hz to 100 kHz (+1dB, -3 dB)
Signal-to-Noise Ratio 110 dB
(Unbalanced, IHF-A)
Speaker Impedance 4 ohms –16 ohms; or 6 ohms–16 ohms


GENERAL:

Power Supply AC 120 V, 60 Hz
Power Consumption 11.7 A
Dimensions (W X H X D) 17 1/8" x 7 13/16" x 17 1/2"
435 × 198.5 × 445 mm
Weight 50.7 lbs (23.0 kg)

[bobless]

onkyo's have had this switch for years...wimpy designed amp section if you ask me. They can't handle 4 ohm loads unless you limit the power output??

[NorthStar]

Alright, the impedance switch on the back (4 Ohms & 6 Ohms) is for the UL seal of approval. That's all there is to it!
And indeed, if you select the 4 Ohms position it will limit the overall current. >> Just don't select it and you have a normal Mutichannel Power Amplifier.

And it is an old standard class AB amp just like Emo amps. The main total filter capacitance is only 44,000 uF (22,000 uF each) but it does the trick nonetheless.
- The two caps are rated at 75 Volts each, and 85 degree Celsius for temperature. ...And there is also some secondary microfarads capacitance from each power module amps.
- In addition to the main toroidal transformer, there are two additional transformers; one on top of one of the fans, and the other one, a much smaller one hiding below the rear near the AC power cord entrance.
- And those power transistors (2 per channel) are extra oversized with lots of power (watts) handling.

The weight is 26.0 Kg / 57.32 pounds (with packaging). The net weight is 23.0 Kg / 50.7 pounds.
...And it's a 9-channel amp, with 150 watts per channel.

List price is $1,699 (MSRP). Street price is .... much lower of course.

INFO: => @ www.intl.onkyo.com/downloads/product_info/pdf/pa-mc5500_ex_leaflet.pdf

[ny1pr2009]

This is from the Onkyo PA-MC5500 manual in reference to the impedance switch at the back of the amplifier,

• You can connect speakers with an impedance of
between 4 and 16 ohms. If the impedance of any of the
connected speakers is 4 ohms or more, but less than 6
ohms, be sure to set the minimum speaker impedance
to “4ohms”

[bigred7078]

Nov 27, 2010 22:56:39 GMT -5 geebo said:

Perhaps when 4 ohm is selected, its cuts the max power available?

That's exactly right. It's a power limiter.

[NorthStar]

Nov 28, 2010 0:12:57 GMT -5 bigred7078 said:

Nov 27, 2010 22:56:39 GMT -5 geebo said:

Perhaps when 4 ohm is selected, its cuts the max power available?

That's exactly right. It's a power limiter.

Every man has that too. It's below the waist, right below our mojo, the dual switch, you know... ;D
...Ask Chuckienut! He knows!

[LCSeminole]

Nov 27, 2010 23:59:48 GMT -5 NorthStar said:

Alright, the impedance switch on the back (4 Ohms & 6 Ohms) is for the UL seal of approval. That's all there is to it!
And indeed, if you select the 4 Ohms position it will limit the overall current. Just don't select it and you have a normal Mutichannel Power Amplifier.

And it is an old standard class AB amp just like Emo amps. The total filter capacitance is only 44,000 uF but it does the trick nonetheless. The two caps are rated at 80 Volts each.
In addition to the main toroidal transformer, there are two additional transformers; one on top of one of the fans, and the other one, a much smaller one hiding below the rear near the AC power cord entrance.
And those power transistors (2 per channel) are extra oversized with lots of power (watts) handling.

The weight is 26.0 Kg / 57.32 pounds. ...It's a 9-channel amp, 150 watts per channel.

List price is $1,699 (MSRP). Street price is .... lower of course.

INFO: => @ www.intl.onkyo.com/downloads/product_info/pdf/pa-mc5500_ex_leaflet.pdf

Bob, Just curious, Why exactly is the switch needed for UL Certification? Just nit-picking here, but the weight you gave was for the carton and it's contents, the actual unit weighs 23kg or an aproximate 50.7lbs.

Question about power rating below: Why only show 1 channel driven as opposed to 5 or 7 channels continuous, being that would be more real world usage, or am I interpreting the specs from your link incorrectly? Why not 5 or 7 channels driven at 4 & 8 ohms? or even 9 channels continuous since its a 9 channel power amplifier?

Power Output:
Front L/R 280 W/Ch (6 Ù, 1 kHz, 1 channel driven, JEITA)
Center 280 W (6 Ù, 1 kHz, 1 channel driven, JEITA)
Surround L/R 280 W/Ch (6 Ù, 1 kHz, 1 channel driven, JEITA)
Surround Back L/R 280 W/Ch (6 Ù, 1 kHz, 1 channel driven, JEITA)
Front Wide L/R or Front High L/R
280 W/Ch (6 Ù, 1 kHz, 1 channel driven, JEITA)

[LCSeminole]

Nov 28, 2010 0:12:57 GMT -5 bigred7078 said:

Nov 27, 2010 22:56:39 GMT -5 geebo said:

Perhaps when 4 ohm is selected, its cuts the max power available?

That's exactly right. It's a power limiter.

Steve, Admitting I'm no power amplifier expert, your statement begs the question: Why would you want to limit the power???

[NorthStar]

Nov 28, 2010 1:02:43 GMT -5 LCSeminole said:

Nov 27, 2010 23:59:48 GMT -5 NorthStar said:

Alright, the impedance switch on the back (4 Ohms & 6 Ohms) is for the UL seal of approval. That's all there is to it!
And indeed, if you select the 4 Ohms position it will limit the overall current. Just don't select it and you have a normal Mutichannel Power Amplifier.

And it is an old standard class AB amp just like Emo amps. The total filter capacitance is only 44,000 uF but it does the trick nonetheless. The two caps are rated at 75 Volts each.
In addition to the main toroidal transformer, there are two additional transformers; one on top of one of the fans, and the other one, a much smaller one hiding below the rear near the AC power cord entrance.
And those power transistors (2 per channel) are extra oversized with lots of power (watts) handling.

The weight is 26.0 Kg / 57.32 pounds. ...It's a 9-channel amp, 150 watts per channel.

List price is $1,699 (MSRP). Street price is .... lower of course.

INFO: => @ www.intl.onkyo.com/downloads/product_info/pdf/pa-mc5500_ex_leaflet.pdf

Bob, Just curious, Why exactly is the switch needed for UL Certification? Just nit-picking here, but the weight you gave was for the carton and it's contents, the actual unit weighs 23kg or an aproximate 50.7lbs.

Laurence, you probably heard of such a switch on all Onkyo/Integra, Yamaha, and several other receivers.
Audioholics has some extensive articles about this impedance switch (reason why it's there, what it does, and what's the best position to select).

=> You never see such a switch normally on separate power amps, but as receivers are more for the mass market, they are more restricted to some UL laws and safety measures for the consumers.

* As for the weight (net), you are right, it is 23 Kg / 50.7 pounds NET. It's still a good chunk of an amp.
{I was indeed looking at the Carton specs!} -> Shame on me! ;D

Question about power rating below: Why only show 1 channel driven as opposed to 5 or 7 channels continuous, being that would be more real world usage, or am I interpreting the specs from your link incorrectly? Why not 5 or 7 channels driven at 4 & 8 ohms? or even 9 channels continuous since its a 9 channel power amplifier?

Power Output:
Front L/R 280 W/Ch (6 Ù, 1 kHz, 1 channel driven, JEITA)
Center 280 W (6 Ù, 1 kHz, 1 channel driven, JEITA)
Surround L/R 280 W/Ch (6 Ù, 1 kHz, 1 channel driven, JEITA)
Surround Back L/R 280 W/Ch (6 Ù, 1 kHz, 1 channel driven, JEITA)
Front Wide L/R or Front High L/R
280 W/Ch (6 Ù, 1 kHz, 1 channel driven, JEITA)

Those are just specs Laurence, they don't mean squat in real world performance. I would think Carlos would know best. But then his Def Tech speakers are quite efficient.

Also, I believe Onkyo is playing safe with its amps, and now have a protective circuit limiter so as to not overriding them (heat, stress...) in particular now that they have 9 power amps in their top receivers and in this separate multichannel amp.

Anyway, Emo amps are still unbeatable for the price and they are worthy of the praises from all around. My XPA-2 and XPA-5 won't be replaced anytime soon by this Onkyo amp. ...But then, I'm still short of two power amps! ...Perhaps two UPA-1s? ;D

Also, you have to consider that Carlos had a real good deal on both components (the amp & the pre/pro).

______________________________

* Here's more on it: @ www.areadvd.de/hardware/2010/onkyo_pa_mc5500.shtml

______________________________

[Porscheguy]

Nov 27, 2010 21:24:49 GMT -5 Lonnie said:

Just a question here, it looks like the amp has an impedance switch on it. Is this correct?

I do believe you are correct......

[ny1pr2009]

Here is an article from HighTech Review magazine in reference to the Onkyo PA-MC5500,

PA-MC5500 THX Ultra 2-certified 9-channel amplifier ¨C New!

Onkyo¡¯s mighty 26kg flagship power amplifier is sure to set any cinephile¡¯s heart fluttering, with a dazzling specification that puts it firmly into high-end territory. Benefitting from a host of exclusive amplifier technologies developed in-house by Onkyo the PA-MC5500 power amplifier is also the perfect partner for the PR-SC5507 Network Controller, having been developed in concert with it.
Why is it a good thing to separate the pre and power sections of an integrated home cinema receiver? Simple¡­ an integrated product by definition, has to accommodate both digital and analogue signals within close proximity of one another, raising the spectre of noise interference. Separate those functions into separate enclosures and you immediately lessen that risk.

Onkyo has opted to eschew digital power amplification for an all-analogue configuration in the PA-MC5500, specifically because it wanted to achieve a full-bodied and audibly musical sound quality, something that¡¯s still far from a given in the home cinema world. Both balanced and non-balanced connections (via gold-plated XLRs) and solid brass RCAs, respectively) are provided but, for best performance, the former are highly recommended (happily, the PR-SC5507 has balanced outputs for all channels, allowing the use of long interconnects).

Each of the PA-MC5500¡¯s nine channels delivers a hefty 220w (into 6 ohms), more than enough to drive an ambitious home cinema loudspeaker system to realistically high levels ¨C at full tilt the amplifier draws more than a kilowatt of power from the mains supply. As THX¡¯s engineers will happily attest the PA-MC5500 will easily deliver the goods in large rooms where viewers are sat more than 12 feet away from the viewing screen.

Based around a weighty steel-plate chassis that¡¯s designed to be as physically inert as possible, this amplifier boasts a huge toroidal power transformer, physically separated from the sensitive amplifier stages by a massive heatsink that runs the full width of the amp. In tandem with large capacity 22,000uf audio-tuned capacitors there¡¯s a guaranteed supply of consistent power on tap under all conditions.

Using a Push-Pull amplifier design with a 3-stage Inverted Darlington Stage (to minimise distortion) the PA-MC5500 uses Onkyo¡¯s famed WRAT (Wide Range Amplifier Technology), a basket of techniques developed over decades that have been proven to deliver high-fidelity cinema sound.

The use of a Low Negative Feedback design, for instance, endows the amplifier with an SACD-friendly frequency response that reaches out to 100kHz while HICC (High Instantaneous Current Capability) allows the PA-MC5500 to stay fully in control when there are speaker impedance fluctuations.

Carefully designed Closed Ground-Loop circuits and low-impedance copper bus plates ensure that circuit noise (created by varying ground potentials) is kept to an absolute minimum and that you hear what the director intended you to hear¡­ and nothing else.

To further guarantee consistent performance, especially when dealing with two-channel music, PA-MC5500¡äs power amplifier channels are designed as wholly separate modules that are identical electrically, structurally, physically and electromagnetically.

Short signal paths, symmetrically laid out power devices, and a fully Discrete Output Stage all play their part in helping the PA-MC5500 deliver ultra-clean high fidelity power to a home cinema¡¯s multi-channel loudspeaker array.

[DYohn]

The power limiter is to meet UL specifications, specifically UL-6500 I believe. Besides, consumer products should be limited to less than 13 amps draw so they can be used in a typical home in the US.

Squeezing 9 class A/B amplifier channels into one chassis is a bit of a feat. Note that the ratings list this with 2 channels driven into 8 ohms or with one channel driven into 6 ohms. Not that anyone would ever drive all 9 channels to anywhere near their rating at the same time, but realize that is also impossible to do with this design.

[LCSeminole]

Nov 28, 2010 10:30:14 GMT -5 DYohn said:

The power limiter is to meet UL specifications, specifically UL-6500 I believe. Besides, consumer products should be limited to less than 13 amps draw so they can be used in a typical home in the US.

Squeezing 9 class A/B amplifier channels into one chassis is a bit of a feat. Note that the ratings list this with 2 channels driven into 8 ohms or with one channel driven into 6 ohms. Not that anyone would ever drive all 9 channels to anywhere near their rating at the same time, but realize that is also impossible to do with this design.

David, Thanks for answering, I had a feeling you would know the technical aspect. I was just curious as I've owned several different brands of 5 channel home theater amplifiers: Carver, NAD, Rotel and obviously Emotiva, and I've never seen an impedance switch on a power amplifier. Not that this shows anything about design, but all of those power amplifiers at 5 channels were way heavier and had heat sinks per channel. I just wondered why so little heat sinks, and why no actual conitunous power ratings for at least 5 channels since the Onkyo is a multi-channel power amplifier and would most definitely be used in at least a 5 speaker setup. Power amplifier build/design/specifications have alway interested me, so my curiosity sometimes gets peaked when I see a design thats off the beaten path.

[DYohn]

Nov 28, 2010 10:47:38 GMT -5 LCSeminole said:

Nov 28, 2010 10:30:14 GMT -5 DYohn said:

The power limiter is to meet UL specifications, specifically UL-6500 I believe. Besides, consumer products should be limited to less than 13 amps draw so they can be used in a typical home in the US.

Squeezing 9 class A/B amplifier channels into one chassis is a bit of a feat. Note that the ratings list this with 2 channels driven into 8 ohms or with one channel driven into 6 ohms. Not that anyone would ever drive all 9 channels to anywhere near their rating at the same time, but realize that is also impossible to do with this design.

David, Thanks for answering, I had a feeling you would know the technical aspect. I was just curious as I've owned several different brands of 5 channel home theater amplifiers: Carver, NAD, Rotel and obviously Emotiva, and I've never seen an impedance switch on a power amplifier. Not that this shows anything about design, but all of those power amplifiers at 5 channels were way heavier and had heat sinks per channel. I just wondered why so little heat sinks, and why no actual conitunous power ratings for at least 5 channels since the Onkyo is a multi-channel power amplifier and would most definitely be used in at least a 5 speaker setup. Power amplifier build/design/specifications have alway interested me, so my curiosity sometimes gets peaked when I see a design thats off the beaten path.

I agree about the lack of heat sinks and the apparent light weight of this amp. If those really are Class A/B modules, the thermal management techniques would be very interesting to me (this is one of the things my company does for certain manufacturers; we design thermal management systems.) When i looked at the amp guts picture you posted, I thought it looked like Class D modules to me - with a large linear power supply.

[LCSeminole]

Nov 28, 2010 1:34:49 GMT -5 NorthStar said:

Nov 28, 2010 1:02:43 GMT -5 LCSeminole said:

Bob, Just curious, Why exactly is the switch needed for UL Certification? Just nit-picking here, but the weight you gave was for the carton and it's contents, the actual unit weighs 23kg or an aproximate 50.7lbs.

Laurence, you probably heard of such a switch on all Onkyo/Integra, Yamaha, and several other receivers.
Audioholics has some extensive articles about this impedance switch (reason why it's there, what it does, and what's the best position to select).

=> You never see such a switch normally on separate power amps, but as receivers are more for the mass market, they are more restricted to some UL laws and safety measures for the consumers.

* As for the weight (net), you are right, it is 23 Kg / 50.7 pounds NET. It's still a good chunk of an amp.
{I was indeed looking at the Carton specs!} -> Shame on me! ;D

Question about power rating below: Why only show 1 channel driven as opposed to 5 or 7 channels continuous, being that would be more real world usage, or am I interpreting the specs from your link incorrectly? Why not 5 or 7 channels driven at 4 & 8 ohms? or even 9 channels continuous since its a 9 channel power amplifier?

Power Output:
Front L/R 280 W/Ch (6 Ù, 1 kHz, 1 channel driven, JEITA)
Center 280 W (6 Ù, 1 kHz, 1 channel driven, JEITA)
Surround L/R 280 W/Ch (6 Ù, 1 kHz, 1 channel driven, JEITA)
Surround Back L/R 280 W/Ch (6 Ù, 1 kHz, 1 channel driven, JEITA)
Front Wide L/R or Front High L/R
280 W/Ch (6 Ù, 1 kHz, 1 channel driven, JEITA)

Those are just specs Laurence, they don't mean squat in real world performance. I would think Carlos would know best. But then his Def Tech speakers are quite efficient.

Also, I believe Onkyo is playing safe with its amps, and now have a protective circuit limiter so as to not overriding them (heat, stress...) in particular now that they have 9 power amps in their top receivers and in this separate multichannel amp.

Anyway, Emo amps are still unbeatable for the price and they are worthy of the praises from all around. My XPA-2 and XPA-5 won't be replaced anytime soon by this Onkyo amp. ...But then, I'm still short of two power amps! ...Perhaps two UPA-1s? ;D

Also, you have to consider that Carlos had a real good deal on both components (the amp & the pre/pro).

______________________________

* Here's more on it: @ www.areadvd.de/hardware/2010/onkyo_pa_mc5500.shtml

______________________________

Thanks Carlos & Bob for the explanation, I knew your combined knowledge on Onkyo would come through. I used to be an Onkyo/receivers guy, but I admit it's been a long time since I've run a home theater receiver on its own or as a pre/pro in my home theater and just haven't kept up with mainstream receivers and their developement. I just have not ever seen an impedance/power limiting switch on a power amplifier, which triggered my interest in the Onkyo power amplifier.

[LCSeminole]

Nov 28, 2010 10:56:51 GMT -5 DYohn said:

I agree about the lack of heat sinks and the apparent light weight of this amp. If those really are Class A/B modules, the thermal management techniques would be very interesting to me (this is one of the things my company does for certain manufacturers; we design thermal management systems.) When i looked at the amp guts picture you posted, I thought it looked like Class D modules to me - with a large linear power supply.

Which is why I was hoping the engineering/technical guru geeks ;D,(did I say that) would comment on design and specs as my education was the straight forward applied mathematics & statistics side of this subject.