Power Needs for SDA-2

Paraclete

I have a pair of SDA-2, and have been using a Sony STR-DB930 receiver to power them (110W/Channel). I use them as the front two speakers in a 5.1 surround system, and at higher volume levels coupled with dynamic audio parts of movies (explosions etc) I hear some popping and clipping. I suspect that it is a lack of power, but 110w does not seem like a small amount. What is the needed power for optimal sound from these wonderful speakers?

F1nut

Welcome to the forum.

You suspect correctly. Either a better AVR or adding a separate amp would improve things greatly. Don't believe for one second that your current AVR is putting out 110wpc of clean, high current power.

There's a lot of info pertaining to AVR's and SDA's buried in here that would be worth reading when you have the time. Enjoy!

Paraclete

So, how much power do you think they need? What AVR's do you like for them?

dkg999

If your current AVR has pre-outs, then I would look for a good quality 100 wpc or more power amp to drive the SDA-2's. Something from Adcom, Parasound, Onkyo, NAD, or other reputable brand would work fine.

Spawndn72

I run my SDA-2's with an Adcom 545(100wpc) and I think I could use twice that.

read-alot

More is better and will be a big surprise for you when you do.

bert26

I used to run my SDA2a's with a Carver CM-1090 (using pre outs) into an Adcom 545 (100 wpc @ 8 ohms). This was more than enough to power them but I think that the sound was so big because I had them in a bedroom.

I am currently running SDA1b's with a Nakamichi PA-5 out of a Nakamichi CA-5. They are currently sent up in my basement and sound a little underpowered (especially when compared to the 2a's). Maybe it just has something to do with difference between the two speakers efficiency and ohm ratings.

In any event - I think 100 wpc from a reputable company should tide you over.

RuSsMaN

60 watts with a couple db headroom should get the 2's plenty loud.

honestaquarian

Paraclete wrote:

I have a pair of SDA-2, and have been using a Sony STR-DB930 receiver to power them (110W/Channel). I use them as the front two speakers in a 5.1 surround system, and at higher volume levels coupled with dynamic audio parts of movies (explosions etc) I hear some popping and clipping. I suspect that it is a lack of power, but 110w does not seem like a small amount. What is the needed power for optimal sound from these wonderful speakers?

Which generation of SDA-2's do you have?Do you have the original SDA-2's?The SDA-2A's?The SDA-2B's? It sounds like you have the older ones.All of the older SDA loudspeakers had an issue with presenting a low impedance load to the amplifier when the crossfeed cable was used(which OF COURSE is ALL THE TIME)So it is not necessarily an issue with how much power you have.It is how much CURRENT you have.Remember the power output rating can be and IS manipulated by manufacturer's ALL the time.To make their products look more favorable to the public.Power(as rated in watts)is voltage times current into a load(that being resistance-but in the case of loudspeakers it is called impedance,since it is CONSTANTLY changing).You can increase the voltage from the power supply if it doesn't put out much current,in order to get the same power output rating and vice-versa.The catch is that voltage naturally sags under load.The point of all of this is simple.Low impedance loads require CURRENT which most A/V receivers CANNOT supply,because the power supply(which happens to be THE most expensive part of a receiver) is cheap.Due to cost constraints to bring it in at a price point.YOU NEED MORE CURRENT to drive these speakers.I used to have the exact same problem with my SDA-1B's being driven by a Realistic(remember THEM?)receiver.I changed to an NAD receiver which put out GOO GOO GOBS of current,problem solved.Just like DKG999 said above.If your receiver has pre outs for the front channels then purchasing a good quality amp from a reputable brand will help.The brands that he listed are good.Sony ES is ALSO good(PLEASE note i said SONY ES and NOT SONY)
Hope this helps and doesn't confuse you too much!

Paraclete

You guys are great! Thanks for the info. I think I will look to get better power. I am not sure if I am up for separates, due to cost factors, but clearly more/better power will help.

BTW: I have the original SDA-2's. I have always loved them, and I think that if I power'em better, I will like them more.

schwarcw

Paraclete wrote:

I have a pair of SDA-2, and have been using a Sony STR-DB930 receiver to power them (110W/Channel). I use them as the front two speakers in a 5.1 surround system, and at higher volume levels coupled with dynamic audio parts of movies (explosions etc) I hear some popping and clipping. I suspect that it is a lack of power, but 110w does not seem like a small amount. What is the needed power for optimal sound from these wonderful speakers?

Welcome to the Club Polk Forums!

I was in the same situation as you when I first got my SDA-2's. I never clipped them though. But when I got a separate amp using the front pre-outs the speakers really started to sing. I have a Parasound Halo A-21, 250 wpc @ 8 ohms. I would recommend at least 200 wpc from a high current amp. There's a lot of good used stuff out there. Good luck and keep us posted.

dudeinaroom

I've got an adcom gfa-555 (200/ch in 8ohms 325/ch into 4 ohms) and I think I could still use more. My receiver does not have pre outs(which is the case with most sonys I have seen) so I used a headphone to rca adaptere cable and made a passive pre amp to set the volume so It would be matched to the rest of the speakers in the system. I have marked the postion of the volume knob for HT use, and if I want more volume for stero listening, I can just crank it up, and then set it back for movies.

TroyD

Quality over quantity. I've got 75 wpc running my 2.3tl's and it's just FINE.

BDT

read-alot

TroyD wrote:

Quality over quantity. I've got 75 wpc running my 2.3tl's and it's just FINE.

BDT

Don't the SDA2 have a diffeent ohm load than the 2.3tl ?

TroyD

It's a moot point.

People can say and believe what they like about power, however, the fact is that all SDA's were around 90db efficient so they don't require THAT much power. Hoosier21 drove 1.2tl's insanely loud on a 20 wpc NAD integrated. Again, 50-60 wpc with a couple db's of headroom will power just about any speaker that you care to imagine.

BDT

read-alot

The 2's are 4 ohm the 2.3tls are 8 ohm. Some amps can't pull 4 ohm loads.

Spawndn72

Don't get me wrong, my 100wpc amp powers the SDA-2's just fine and they get plenty loud. I just think they could handle 2-3 times more and maybe be even better.

TroyD

The ohm rating is an average taken accross the response band. Again, a competently designed amp with 50wpc and a couple of db headroom will drive any SDA speaker as loud as you want to listen.

BDT

Spawndn72

TroyD wrote:

The ohm rating is an average taken accross the response band. Again, a competently designed amp with 50wpc and a couple of db headroom will drive any SDA speaker as loud as you want to listen.

BDT

Ok, just popped Metalica's "... And Justice for All" into the cd player, cranked the pre-amp up to 12 O'clock(starts to clip at 1 O'clock, so I like to be on the safe side). Listend to all of "Blackened" and most of "One". It was plenty loud, loud enough that from 8 feet away I could feel the music. Feel, as in things were vibrating. This is in a room that is 24x13x8.

Now that is probably as loud as TroyD wants to listen to music. However there are times that I would like it to be louder. Concert level louder.

So it kinda depends on just what you think loud is. If you want your ears to be ringing, then you will need more power than I have. If not then TroyD might be right.

BTW incase you did not read my earlier post. I am running an Adcom 545 which is 100wpc and I think it is a quality amp.

F1nut

read-alot wrote:

The 2's are 4 ohm the 2.3tls are 8 ohm. Some amps can't pull 4 ohm loads.

The 2.3TL's are 6 ohm nominal.

I think you're talking about AVR's because if an amp can't do a 4 ohm load, it's not an amp worth owning. In fact, I can't think of a single amp that won't do 4 ohm loads. Do you have an example?

However there are times that I would like it to be louder. Concert level louder.

Rock concert level is about 120-125dB at one meter. Do you know how loud that really is. I've run my 2.3TL's up to a fairly steady 115db, peak at 117dB and it will hurt your ears, believe me.

read-alot

F1nut wrote:

The 2.3TL's are 6 ohm nominal.

I think you're talking about AVR's because if an amp can't do a 4 ohm load, it's not an amp worth owning. In fact, I can't think of a single amp that won't do 4 ohm loads. Do you have an example?




Rock concert level is about 120-125dB at one meter. Do you know how loud that really is. I've run my 2.3TL's up to a fairly steady 115db, peak at 117dB and it will hurt your ears, believe me.

SRS2.3TL
Floor-standing home stereo loudspeakers.
Listen carefully...everything you hear is true.

55" H x 20-5/8" W x 13-1/8" D
( 139.70cm H x 52.39cm W x 33.34cm D )

Available Finishes
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MSRP:
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Overview Specifications Customer Reviews


Driver Complement
Subwoofer 1 - 15" Diameter (38.10cm)
sub bass radiator
Midrange 6 - 6-1/2" Diameter (16.51cm)
drivers
Tweeter 3 - 1" Diameter (2.54cm)
SL3000 trilaminate dome tweeters

---

Electrical
Overall Frequency Response 12Hz-26kHz
Lower -3dB Limit 30Kz
Upper -3dB Limit 25kHz
Nominal Impedance 8 ohms

read-alot

Another quote that may help someone.

"Many amps manufactured these days are rated only for 8-ohm-and-above loads, and not for 4-ohm loads. This is done largely as a cost savings by the manufacturer. Amps which are capable of driving 4-ohm loads to the same output voltage require heftier power supplies, heatsinks, and (often) output-stage transistors: they'll be delivering twice as much current into the load, and will be dissipating roughly twice as much heat within their output stages.

If a manufacturer chooses to quote a power rating at 4 ohms in their advertising, the amp must be capable of delivering this much power after a 'warmup' period of operation at 1/3 power (which level actually dissipates _more_ heat in the output stage than full-power operation).

In order to save money during manufacture, manufacturers often use skimpier power supplies, heatsinks, and output stages - and as a result, the amps may have a 4-ohm power rating which is _less_ than the 8-ohm rating. This is somewhat embarrassing for the manufacturer to advertise - and, so, they often do not quote a 4-ohm power rating at all, and state that the amp is designed to be used only with loads of 8 ohms or above.

With many such amplifiers, you can drive a 4-ohm load safely, as long as you don't try to drive it too hard. If you drive a low-Z load to too high a volume, one of several things may happen: the amp may begin to "clip" (sounds very harsh and distorted, may damage the tweeters), or may overheat and shut itself down, or may overheat and burn up (all the magic blue smoke leaks out)".

F1nut

Ummm....it says they are "compatible" with 8 ohm outputs. If you were to actually measure them you'd see that they are 6 ohm. Polk also says the CRS+ are 6 ohm nominal, but if you measure them, they are 4 ohm. Don't believe everything you read.


Again, do you have an actual example? I know of no power amp that isn't rated to drive a 4 ohm load.

read-alot

Jesse, we are talking about these aren't we.

http://www.polkaudio.com/homeaudio/specs/srs23tl/

I don't believe anything I read, and half of what I see.

F1nut

The one and the same.

honestaquarian

honestaquarian wrote:

Which generation of SDA-2's do you have?Do you have the original SDA-2's?The SDA-2A's?The SDA-2B's? It sounds like you have the older ones.All of the older SDA loudspeakers had an issue with presenting a low impedance load to the amplifier when the crossfeed cable was used(which OF COURSE is ALL THE TIME)So it is not necessarily an issue with how much power you have.It is how much CURRENT you have.Remember the power output rating can be and IS manipulated by manufacturer's ALL the time.To make their products look more favorable to the public.Power(as rated in watts)is voltage times current into a load(that being resistance-but in the case of loudspeakers it is called impedance,since it is CONSTANTLY changing).You can increase the voltage from the power supply if it doesn't put out much current,in order to get the same power output rating and vice-versa.The catch is that voltage naturally sags under load.The point of all of this is simple.Low impedance loads require CURRENT which most A/V receivers CANNOT supply,because the power supply(which happens to be THE most expensive part of a receiver) is cheap.Due to cost constraints to bring it in at a price point.YOU NEED MORE CURRENT to drive these speakers.I used to have the exact same problem with my SDA-1B's being driven by a Realistic(remember THEM?)receiver.I changed to an NAD receiver which put out GOO GOO GOBS of current,problem solved.Just like DKG999 said above.If your receiver has pre outs for the front channels then purchasing a good quality amp from a reputable brand will help.The brands that he listed are good.Sony ES is ALSO good(PLEASE note i said SONY ES and NOT SONY)
Hope this helps and doesn't confuse you too much!

You guys keep going over the above information.Pretty lively debate though.My Realistic receiver could drive my old SDA-1B's---until i turned up the volume.Then the protection circuitry would shut it down,because the impedance would dip too low for it to safely drive.All of the older SDA's had this same issue with a low impedance load.The newer ones had changes to the crossovers so this was no longer an issue.Or at LEAST not as big an issue.:rolleyes:

Spawndn72

F1nut wrote:

The 2.3TL's are 6 ohm nominal.

Rock concert level is about 120-125dB at one meter. Do you know how loud that really is. I've run my 2.3TL's up to a fairly steady 115db, peak at 117dB and it will hurt your ears, believe me.

I know what you mean, I am just saying that I could stand for system to be a bit louder at times. I do not have a db meter so I have no idea how loud it really is, I just know that I could stand for it to be louder.

For the most part though....like 99.5 percent of the time, my system is more than loud enough, and I keep the volume level around 10-11 o'clock.

dudeinaroom

F1nut wrote:

Ummm....it says they are "compatible" with 8 ohm outputs. If you were to actually measure them you'd see that they are 6 ohm. Polk also says the CRS+ are 6 ohm nominal, but if you measure them, they are 4 ohm. Don't believe everything you read.


Again, do you have an actual example? I know of no power amp that isn't rated to drive a 4 ohm load.

Impeadance is the measure of ac, resistamce is the measure of dc. If you use a multi meter your are reading the dc resitance of the speaker, and not the ac impedance. Amps put out ac signals so that would be the proper measure.

Sorry f1 nto trying to knock you.:rolleyes:

F1nut

I'm always up for schooling. So, exactly how would you determine the nominal ohm rating of a speaker?

honestaquarian

Actually i was wondering the same thing myself that F1nut was asking.Considering the fact that EVERY time the driver moves the impedance changes.Do you take an average over some frequency spectrum?Thanks for that very useful information.

heiney9

Impedence varies with frequency and amplitude. Not to mention the speaker cables, inter connects and their associated lengths, materials and build quality. A nominal rating is an average as TroyD has stated. TroyD and F1 are competely correct in their analysis.

Read-alot, your splitting hairs and really the impedence shouldn't be an issue at all if you are using even a modestly competent amp or receiver. Certainly more power in almost any situation is better; is it necessary to power the later generation SDA's..........no.

Because of the varying amplitude and frequency, impedence is infinitely variable.

H9