Amplifier help

[John Hoskin]

I have a pair of Polk RTI A9's powered by an Onkyo SR805. They currently sound good but would sound better with more power of course, as of right now they are not getting half the recommended power, which brings me to my question. To mono or not to mono. I'm looking into an emotiva amps, and was contemplating a bi amp supplying them with 300 watts rms or would it be beneficial enough to justify the extra money to give each speaker a mono amp supplying 500watts rms to the towers, max recommended amperage. Any help would be appreciated, as i have never had the luxury of hearing the difference between the two configurations.

Thank you all in advance.


Further thought, also considering mono for future upgrades?

 

[agarwalro]

John,

Welcome to the forum.

The Watt rating of a speaker doesn't mean the amp needs to put out a corresponding amount of power. Only if the amp is clipping can you say that it is running out of juice. In most AVRs and amps made today the protection circuitry will present clipping and instead cause a shut down. Also, clipping in the amp is very noticeable. That Onkyo is no slouch. Unless you're looking for ear bleeding volume, I doubt it is running out of juice.

Monoblocks are good for audio snobbery, but the numbers on paper seldom correspond with measurable real world improvement when compared to properly designed and well implemented multi-channel amp. Passive bi-amping (amp given full range signal and crossovers components placed after amp) is also a waste with questionable benefits.

Rather than monoblocks and passive bi-amping the Polks, spend the money on room treatments and the improvement in sound will be significantly more. If you must add an external amp, an Emotive XPA-3 for the mains and center will be more than sufficient.

 

[baniels]

For what it's worth, I have that same receiver and I have three-way mains that are 88db sensitive (yours are 89db).

I bought the XPA-2 in late October. The jump from 130 to 265 watts was a sufficient increase to get as much out of my speakers as I can ever imagine wanting. With the Onkyo, the sound would start to come apart at the upper end of my louder listening sessions. With the XPA-2, their is no noticeable deterioration of sound quality at dangerously loud levels.

I can't imagine a pair of XPA-1's benefiting my system in an appreciable way. I've never seen the red lights on the XPA-2 and the meters (when I occasionally use them) don't get much past halfway very often.

 

[zumbo]

I built a dedicated 2-channel system. I have spent years here at Audioholics listening to people say bi-amping is a waste of time. My DEFINITE answer is, it depends.

My experience based on MY equipment.
I started with (1) Denon POA-2200 amp, and (2) MB Quart QL-S830(4ohm/87db.) The sound was impressive, but the treble would flatten-out when pushed. Pushed a little harder, the mids(6.5" woofers) would slap. At first, I thought it was overpowering the speakers. The Denon POA-2200 is a pretty sweet amp.

I added another Denon POA-2200. Had Bluejeanscable custom make vertical bi-amp cables for each amp. Each amp has gain controls for each channel. With this, I am able to control the gain separate for the tweets/mids. This is an invaluable feature. The treble NEVER flattens-out. It remains extremely detailed. The mids NEVER slap, and it's truly amazing how much output I get from these two sets of speakers.

System is playing full-range, with no sub.

 

[zumbo]

In a HT environment, I doubt it would be worth the money. I started with a Yamaha RX-V1400 in my HT. Later, added an Adcom 5-channel amp. Later, switched to a Yamaha RX-Z7. While each improvement was justifiable, the sound never changed that much. There is just so much going on with a 5.1 speaker system, along with the quality of the 5.1 media.

This is why I built a separate 2-channel music only system. I took my time, and watched for good deals. VERY glad I built a separate 2-channel system.

 

[AcuDefTechGuy]

I have a pair of Polk RTI A9's powered by an Onkyo SR805. They currently sound good but would sound better with more power of course...

How do you know?

I bet they sound exactly the same.

At what speaker channel level do you have the Onkyo set? Are they at ZERO? Or -2dB or -3dB or more?

Some people run Audyssey or other room correction and end up with the channel levels in the negative. Some like -10dB. And then they have to crank up the master volume to +1 dB to get enough volume. And they wonder why the receiver goes into protection mode.

I make sure the lowest level is set to zero.

 

[mtrycrafts]

How do you know?

.....

Oh, the dark side is very powerful....

 

[agarwalro]

Each amp has gain controls for each channel. With this, I am able to control the gain separate for the tweets/mids.

That's a hybrid setup either than 100% passive bi-amped like the OP wants to do .

 

[zumbo]

That's a hybrid setup either than 100% passive bi-amped like the OP wants to do .

Just so you are clear, I have one 2-channel amp on the left speaker, and an identical 2-channel amp on the right speaker. The amps have separate gains for each channel. Each amp has two gains, for a total of four. So, I have a gain control for each tweeter, and each 6.5" parallel sets.

Vertical passive bi-amp.

 

[PENG]

That's a hybrid setup either than 100% passive bi-amped like the OP wants to do .

His is still set up as passive bi-amp, separate gain control or not. I agree with him, despite many had dispelled the benefits of passive bi-amping but it really does depend....... Besides, at least one reputable amp manufacturer openly suggested passive bi-amping is actually the way to go. We can read into that statement and surmise that perhaps they thought the average audiophile could do passive right but may mess up if they try active, but that would be just speculation. IMHO, passive bi-amping can improve SQ in some people's system/application but not others.

 

[agarwalro]

Just so you are clear, I have one 2-channel amp on the left speaker, and an identical 2-channel amp on the right speaker. The amps have separate gains for each channel. Each amp has two gains, for a total of four. So, I have a gain control for each tweeter, and each 6.5" parallel sets.

Vertical passive bi-amp.

That POA 2200 being a beast of an amp not withstanding, adding the second amp most likely gave the dynamic headroom needed by your inefficient speakers (especially since you don't have subs). A direct connected amp with sufficient power might have yielded similar improvement in speaker performance.

The gain control in your setup is no different than tone controls on an integrated amp. It may sound better, but only serendipity would make it more accurate.

His is still set up as passive bi-amp, separate gain control or not.

+ 1.

Besides, at least one reputable amp manufacturer openly suggested passive bi-amping is actually the way to go. We can read into that statement and surmise that perhaps they thought the average audiophile could do passive right but may mess up if they try active, but that would be just speculation.

Aren't they simply selling more amps to folks that don't know better? That said, to your point, it would take considerable skill to get 100% active setup dialed in perfect.

My DEFINITE answer is, it depends.

passive bi-amping can improve SQ in some people's system/application but not others.

I concede, it may be beneficial to some.

 

[zumbo]

The gain control in your setup is no different than tone controls on an integrated amp. It may sound better, but only serendipity would make it more accurate.

I disagree. I am not boosting/cutting frequencies to be sent to the cross-over networks in my speakers. I am boosting/cutting power of the entire amplified bandwidth, and allowing the cross-over networks to do what they were designed to do. The media remains as is was recorded. The bi-amp set-up has eliminated the ping-pong effect of the heavy bass note draws diminishing the quality of the treble. Having two amps has enabled the mids to have more than enough power on tap to keep the amps way below clipping. Prior to the second amp addition, the treble would flatten-out/loose detail, and I would get a slap from one or more of the mids. That was clipping.

First-hand experience with my own equipment. It's not debatable for my application.

And on top of that, I have 0 chance of noise coming from a pre-amp that would be part the integrated amp you speak of. All I have is a cd player connected to the amps. The cd player has remote gain.

 

[96cobra10101]

"I smoked pot with Johnny Hoskins."

"You don't know anyone named Johnny Hoskins."

"It was Johnny Hoskins and Sloan Kettering. And they were blazing that **** up every day."

 

[zumbo]

You have to understand that these speakers are (4ohm/87db.)

You also have to understand that each speaker only has (2) 6.5" mids, and (1) 1" tweeter. There has to be a huge amount of power to reach the dB I prefer.

There is no powered sub. The speakers are playing full bandwidth.

 

[ichigo]

The SR805 can push out over 300Wpc into 4 ohms, and over 300Wpc into 8 ohms in bi-amp mode; you are going to need some seriously gigantic amps to outdo your current receiver.

These were Sound & Vision measurements:

Output at clipping (1 kHz into 8/4 ohms)
1 channel driven: 201/322 watts (23/25.1 dBW)
5 channels driven (8 ohms): 141 watts (21.5 dBW)
7 channels driven (8 ohms): 128 watts (21.1 dBW)
Distortion at 1 watt (THD+N, 1 kHz)
8/4 ohms: 0.02/0.03%
Noise level (A-weighted): -76.1 dB
Excess noise (with sine tone)
16-bit (EN16): 0.7 dB
Frequency response: 20 Hz to 20 kHz +0, -0.8 dB

STEREO PERFORMANCE, DIGITAL INPUT

Reference level is -20 dBFS; all level trims at zero. Volume setting for reference level was 6.5.

Output at clipping (1 kHz, both channels driven)
8/4 ohms: 185/320 watts (22.7/25.1 dBW)
Distortion at reference level: 0.02%
Linearity error (at -90 dBFS): 0.2 dB
Noise level (A-weighted): -75.6 dB
with 96-kHz/24-bit signals: -88.8 dB
Excess noise (with/without sine tone)
16-bit (EN16): 0.3/0.3 dB
quasi-20-bit (EN20): 9.6/9.9 dB
Noise modulation: 0.2 dB
Frequency response: <10 Hz to 20 kHz +0, -0.8 dB
with 96-kHz/24-bit signals: <10 Hz to 44.5 kHz +0, -1.7 dB

Bridged output at clipping was in excess of 300 watts, two channels driven into 8 ohms.

 

[zumbo]

and for the money it would take to make an arguably slight difference in your current set-up that may lead to disappointments, you could have the joy of building a music only 2-channel rig with new/used components for about the same money.

I have a little over 1k in my 2-channel rig. It's shocking just typing that fact! Patiently watched, and waited. Won auctions for extremely unbelievable prices.

 

[walter duque]

I have my only my center channel passive bi-amped with 350 watts X 2 into 8ohms. I can't tell the difference with 350 watts or 700 watts total. With 7 speakers and 4 subs it's hard to tell.

 

[mtrycrafts]

You have to understand that these speakers are (4ohm/87db.)

You also have to understand that each speaker only has (2) 6.5" mids, and (1) 1" tweeter. There has to be a huge amount of power to reach the dB I prefer.

There is no powered sub. The speakers are playing full bandwidth.

At 100 watts into a 4 Ohm load should give you 107 dB at 1 meter. I guess that may not be loud enough?
At that rated power, 25 dB 112 dB spl peaks is pretty loud.

 

[zumbo]

At 100 watts into a 4 Ohm load should give you 107 dB at 1 meter. I guess that may not be loud enough?
At that rated power, 25 dB 112 dB spl peaks is pretty loud.

I have seen the math here for years. Means nothing to me at this point.

If one amp is clipping enough to give me a slap from a speaker while the treble flattens-out, math is not going to help my situation.

This was a personal experiment for several reasons.

(1) I won an auction for a great pair of speakers at an unbelievable price.

(2) Happened-up on a hot streak with the old-school Denon amps being listed in low-bid auctions.

(3) I wanted to.

 

[zumbo]

One has to also understand that I very well may not be sending any more power than I was with one amp. In fact, I would put money on it. It's just not at clipping. Pretty simple to understand to me.

The amps don't even get hot.