Do they REALLLY need that much power?

iliveinyourhead

So i am pretty new to my pair of SDA SRS 2's (1986).. I keep reading posts about need more power, get a big big amp. To this i am pretty confused and surprised.
I am driving my pair with a Yamaha PC2002M (has meters), and even at levels i know my neighbors than hear through my plaster walled house and into their plaster walled house i dont see my meters going over 50w. even getting to 50w was WAY loud.

So i am wondering what level everyone is listening to their rigs at in order to really say you need monster watts?

seabeerob213

morequality power = less distortion, you can push a weak amp to play loud, but you will push distortion to your speakers and lose your tweeters

pitdogg2

well its not all about power it is about the current also. In looking at that amps specs I see no where were it has a 4ohm rating. 8/16 ohm no 4ohm. Just because you have 500wpc does not mean you use that much it's about the ability of the amp to drive the speakers without clipping the signal that is what destroys tweeters and voice coils. From what I could find that amp is 120wpc in stereo. Do you use the interconnect cable with the SRS2's?

iliveinyourhead

i use the interconnect yes.

my question is more a general not specific to my current setup. in my setup my ears tell me it sounds great. I am just questioning the true need for large amps i see many of the threads recommending to new SDA SRS owners posting looking for info.

xjghost

What amps would be good for the 3.1's I have? Running a Hafler 500 in stereo and have thought about a set of Carver amps. Thoughts? What other brands and other amps should I be looking for?

Schurkey

Best thing is to re-calibrate your mind. STOP thinking in terms of "watts"; start thinking in terms of dBW. When you get "converted" to dBW, lots of watt-based misunderstanding falls away--starting with how much "power" it takes to make a difference in volume level. Better still is to separate "watts" or even dBW into the component voltage and amperage.

Next, we have to consider the accuracy of amplifier power meters. Most "watt meters" are actually measuring voltage, but the meter face is printed in watts. 50 watts on the meter, could really be 100 watts delivered to the speaker, if the speaker is 4-ohm but the meters are calibrated for an 8-ohm load. There's also the issue of meter accuracy, along with the inability of the meter to register instantaneous peaks.

Remember that Ohm's Law applies even to Audio; it's still about ohms, volts, and amps; with capacitance, inductance, and impedance thrown in to make things interesting. Folks say that Polk speakers need a high-current amp. This is dependent on your view of "high current". To me, a 4-ohm (nominal) load isn't excessively low. An audio amp that has trouble with a 4-ohm nominal load is either of substandard design; or faulty. By contrast, a one-ohm nominal speaker needs a "high current" amplifier! At the time that these speakers were new, 100+ watts per channel was on the huge end, and most decent equipment would handle a 4-ohm load without too much stress. Now that Big Business owns the Federal Trade Commission, making the FTC their lap-doggie instead of a consumer advocate, we see obviously under-designed amplifiers advertised at insanely-high "watts" specs...at ten percent distortion, or over an unrealistically-restricted frequency range, or without the ability to throw current into a 4- or even 6-ohm load without messing the bed.

Polk advertised their speakers as "Easy to drive" except, of course for the requirement for a common-ground amp; and the 4-ohm impedance.

What amp do you need: How loud do you want to play? How big (and how lively/dead) is your room?

I drove my 4-ohm nominal 1Bs with a "120-watt" **** receiver for years. Sounded fine, until the receiver developed some reliability issues. Of course, this was in a series of small-to-medium rooms. The volume knob rarely went past "3".

A Hafler 500 (a friend of mine has multiple Hafler amps, and loves them) is entirely suitable for driving Polk speakers, IF (big IF) it's in good condition. The older Haflers were kind of known for their "FET--Flame-Emitting Transistors) and the input boards are somewhat fragile. All of this is fixable, and Musical Concepts (and others) can set you up better than new. Not much different for Carver gear. IF IT'S WORKING PROPERLY, it's fine stuff, and will easily handle a 4-ohm nominal load--but in modified form, it's exceptional. The story is the same for dozens of brand-names--if the equipment isn't defective, it'll be just fine; and there may be aftermarket support to take them beyond their "factory specs". Keep in mind that any amplifier older than 20 years is probably going to need service work.

In contrast, receivers especially "AV receivers" are pretty-much hated on this forum; and with some good reason. Truth is, there is NO reason a receiver can't drive Polk speakers as well as "separates"; the problem is in the execution, not the concept. There's nothing inherently wrong with a receiver, but virtually all of them are deliberately sabotaged in terms of audio performance in order to cut costs. THAT is the real problem: when you describe your product in terms of watts, and watts are volts X current, it becomes real easy and profitable to build product with lots of voltage and hatefully little current. Volts are cheap, current (amperes) are expensive.

iliveinyourhead

nice reply. thanks.

It's nice to see a response saying you have used a receiver to power your polks.

Schurkey

double-post, sorry.

iliveinyourhead

I have yet to listen to mine from my Pioneer SX1980 or my Yamaha RX-A3020 (AVR). I'll play with them at some point to see if i can hear a different sound.

Schurkey you are correct i did calibrate my PC2002M Meters with an 8ohm load, but they are calibrated per spec so i'm not sure what happens to them on a 4ohm load.

Schurkey

iliveinyourhead wrote: »

Schurkey you are correct i did calibrate my PC2002M Meters with an 8ohm load, but they are calibrated per spec so i'm not sure what happens to them on a 4ohm load.

Current, and therefore wattage, doubles when impedance drops from 8 ohm to 4 ohm. 50 watts indicated, is really 100 watts. (if the meter is accurate.)

iliveinyourhead

i'm just happy to see the meters move they really barely move with my Klipschorns :0)

Mystery

I was at a friend's place.
He has JBL array speakers ($12K I think) powered by McIntosh MC602 600 wpc amplifier plus four more amps for mid bass (one 15" each side) and low bass (one 18" each side).
We listened not even 8 feet away and they sound amazing.
Very clean, crisp and clear. I can feel the thump but never harsh even at very loud levels.

Back to power... I watched power meters on the MC602 and most of the time it was around 50 - 60 watts but every now and then meters went past 500 watts sometimes for just a few fractions of a second while others little longer.
It needed that much power for some notes and it delivered without any stress.
If the amp itself was 50 wpc, those notes demanding 500+ watts will put stress and the notes won't sound clean.
That's my highly non-technical answer.

pitdogg2

Mystery wrote: »

Back to power... I watched power meters on the MC602 and most of the time it was around 50 - 60 watts but every now and then meters went past 500 watts sometimes for just a few fractions of a second while others little longer.
It needed that much power for some notes and it delivered without any stress.
If the amp itself was 50 wpc, those notes demanding 500+ watts will put stress and the notes won't sound clean.
That's my highly non-technical answer.

Highly non-technical but true none the less I see the same thing on my TFM45 all the time while playing Stevie Ray Vaughan. Sometimes while plucking his guitar the meters will just bury themselves while 97% of the content it 30-50 watts on the meter.

We call that headroom if you tried to do the same on a lesser amp I'm sure that signal would square as all get out. ie clipping and sending bad mojo to the speaker

MarkTX

i don't listen loud usually, but there are those times when i want to crank up a certain part of a song. I hit my rta15tl's with about 600 watts peak of nice clean power for a short duration and sounded like they wanted more

Schurkey

Mystery wrote: »

most of the time it was around 50 - 60 watts but every now and then meters went past 500 watts sometimes for just a few fractions of a second while others little longer.

pitdogg2 wrote: »

Sometimes while plucking his guitar the meters will just bury themselves while 97% of the content it 30-50 watts on the meter.

If I put an indicated 50 watts "average" power into my speakers, the neighbors across the street and three houses over could listen to them. My eardrums would meet in the middle of my head on peaks. Back when I had that receiver connected to my "main" speakers, 97% of the time, the meters didn't go over ONE watt, (really, more like 1/3 watt) never mind 30 to 60 watts. (No wattmeters on the Aragon amp I use now, but I suspect similar power levels for "normal" listening.)

Thus listening level (and therefore room size and "liveliness") is so crucial to selecting an amp with enough power for your needs.

drumiv

iliveinyourhead wrote: »

I have yet to listen to mine from my Pioneer SX1980 or my Yamaha RX-A3020 (AVR). I'll play with them at some point to see if i can hear a different sound.
When I first got my SRS's, '85's. 4ohms, the only thing I had was my SX 1980. It sounded awesome. However, it did shut down once, granted, volume was at 1 o'clock. This is a rebuilt unit, in better-than-new cond. My tech begged me not to continue using, as parts are near non-excitant. My point is although it did well, it was very hard on it. They are now powered by 2 Parasound 2200II's, that hardly break a sweat.

F1nut

Do they REALLLY need that much power?

That will depend on a number of factors, one being the efficiency of the speakers one is trying to drive. For example, your SRS 2's are 92dB efficient. My 2.3TL's are 90 dB. For you to achieve a SPL of 110 dB it would take 64wpc. For mine it would take about 200wpc.

That said, one should never under estimate the importance of having enough reserve power on hand. Not only for those times when the urge to rock out hits you, but more importantly to reproduce all that is there at lower volume levels, which is something that a lot of folks don't seem to understand. Unless one experiences that for themselves, they just don't know what they are missing.

There was someone (I forget who and what speakers) that figured out it would take 1000 wpc to accurately reproduce the sound of scissors snipping. Of course, that sound would happen so fast that the meters on any amp would never be able to react fast enough for you to see it. Yeah meters look cool, but don't put any faith in them telling you exactly what your amp is doing.

BTW, I don't care what speakers one is trying to drive, thinking that a receiver is going to drive them properly is only fooling yourself.....never going to happen, ever. The power supply in a receiver is no match for a power amp.

F1nut

Let add another comment. When your amp is pushing out those 64 wpc to obtain 110 dB, there isn't hardly any headroom left and it will sound very loud to your ears because the sound becomes sharp and strained. When my amp is pushing 200 wpc to obtain the same SPL, it still sounds smooth as silk because there is still a lot of headroom at over 500 wpc.

Phish56466

If you can afford it YES, GET MORE. BUT if it sounds good, listen too it. F1nut is DEAD ON though-HEADROOM! You might not need it, but it's nice to have it(your tweeters will thank you).

[Deleted User]

Hi Jesse,
This is taken from Bob Carver's M-1.5 product brochure:

"Once Bob Carver visited a famous sound researcher who was attempting to recreate the "snip" of an ordinary pair of scissors. Between the microphone and the speakers he had installed TWENTY-FOUR 200-watt amplifiers. Yet when viewed on an oscilloscope it was apparent that the final tip of that instantaneous transient was being distorted. Believe it or not, he needed more power!
Bob was blown away, but not exactly surprised. Even playing back a recording of his daugher's first cries had exhausted even HIS enormous sound system's power reserves. It was evident that real- world sound occurs very quickly and requires much more power than ANY current ampl ifier could produce."

Enjoy, Ken

TennMan

I can understand the need for an amp with lots of power and headroom. What I don't understand is how the guys here on the forum with the best gear, and the most knowledge, seem to be very happy with 30-50 watt tube amps and often recommend them over the high power amps. Could someone please explain why a low power tube amp is often preferred over a high wattage, high current amplifier?

motorstereo

TennMan wrote: »

I can understand the need for an amp with lots of power and headroom. What I don't understand is how the guys here on the forum with the best gear, and the most knowledge, seem to be very happy with 30-50 watt tube amps and often recommend them over the high power amps. Could someone please explain why a low power tube amp is often preferred over a high wattage, high current amplifier?

Hmmm; I'd be interested in knowing that as well. I have a pair of relatively high power tube mono's (85wpc) and an A1 interconnect. I keep thinking about trying those monos on my 1.2tl's but my thoughts are it would be an exercise in futility. I currently use a 650wpc Mcintosh power amp and I just can't see them bettering the sound of the mac in any way.

tonyb

TennMan wrote: »

I can understand the need for an amp with lots of power and headroom. What I don't understand is how the guys here on the forum with the best gear, and the most knowledge, seem to be very happy with 30-50 watt tube amps and often recommend them over the high power amps. Could someone please explain why a low power tube amp is often preferred over a high wattage, high current amplifier?

Depends on what they are driving with said amps and how loud they listen. To some, they much prefer the silky smooth top end tube amps are famous for.....or an expansive snappy midrange, but they never listen all that loud or use speakers that don't have a lot of drivers and are fairly easy to drive. When you get into multiple big drivers on floorstanders, low wattage tube amps won't cut it. That's when you get into 100-200 watt tube amps which cost come coinage.

Big multiple driver speakers need a lot of power to start and stop all those drivers as the musical transients present themselves. This is where SS amps excel and why most prefer adding that tube flavor in the pre amp stage and use a SS amp. More power is beneficial, even when not needed most the time, rather than not enough.

Phish56466

tonyb has a point also-listening habits. I PERSONALLY like mine loud when I do listen, otherwise it's an HT rig. Someone correct me if I'm wrong, but doesn't the dampening factor of an amplifier come into play, pertaining to this conversation(i.e. higher is better as far as control)?

xjghost

Thanks for all the info. I had the Hafler looked at recently. I haven't and don't plan on pushing it till I can get it reworked by Musical Concepts. Generally I push it to half the volume level but not much more then that. I'm scared to. I am not familiar with dBW at all. Going to research that some more. I heard somewhere you needed 3x's your current watts to double your volume. I know at louder levels it seems like my speakers need more. I'm not an audio expert nor do I know much about electronics, but I know what I like that that is clean undistorted music and loud levels some times.

F1nut

Kenneth Swauger wrote: »

Hi Jesse,
This is taken from Bob Carver's M-1.5 product brochure:

"Once Bob Carver visited a famous sound researcher who was attempting to recreate the "snip" of an ordinary pair of scissors. Between the microphone and the speakers he had installed TWENTY-FOUR 200-watt amplifiers. Yet when viewed on an oscilloscope it was apparent that the final tip of that instantaneous transient was being distorted. Believe it or not, he needed more power!
Bob was blown away, but not exactly surprised. Even playing back a recording of his daugher's first cries had exhausted even HIS enormous sound system's power reserves. It was evident that real- world sound occurs very quickly and requires much more power than ANY current ampl ifier could produce."

Enjoy, Ken

Thank you very much Ken.

Deadof_knight

you need the power of the gods ....... more is definitely better for the 1.2's

Schurkey

Kenneth Swauger wrote: »

Hi Jesse,
This is taken from Bob Carver's M-1.5 product brochure:

"Once Bob Carver visited a famous sound researcher who was attempting to recreate the "snip" of an ordinary pair of scissors. Between the microphone and the speakers he had installed TWENTY-FOUR 200-watt amplifiers. Yet when viewed on an oscilloscope it was apparent that the final tip of that instantaneous transient was being distorted. Believe it or not, he needed more power!
Bob was blown away, but not exactly surprised. Even playing back a recording of his daugher's first cries had exhausted even HIS enormous sound system's power reserves. It was evident that real- world sound occurs very quickly and requires much more power than ANY current ampl ifier could produce."

Enjoy, Ken

How do you connect 24 amplifiers to "the speakers"? How many speakers were involved? What kind of speakers? What was the volume level he was trying to achieve (everyone assumes--but it is never stated--that the intended volume level was "unity gain", in other words the scissors clip was intended to be reproduced at lifelike level, not louder or softer. The guy could have been trying to recreate the scissors clip at The Who Stadium Concert volume level.) How was an oscilloscope connected to this system of microphone, 24 amps, and "the speakers"?

Bob Carver was a two-way genius: Creative thinking in Physics, and creative thinking in Marketing. I have REAL respect for the physics part of that.

tonyb wrote: »

but they never listen all that loud or use speakers that don't have a lot of drivers and are fairly easy to drive. When you get into multiple big drivers on floorstanders,

The amp sees the speaker load as impedance + phase, not the number of drivers.