SDA-2B power handling

gmcman

Sorry, but I have searched...and cannot locate the specs on this.

I understand people feed these things with big amps but would like to know what the published specs are.

F1nut

30-350 wpc.

gmcman

Thank you.

Presumably the 350 is RMS?

Schurkey

gmcman wrote: »

Thank you.

Presumably the 350 is RMS?

There's more to it than that...right?

I just read through my 1B instruction manual, there's no mention of max power the speaker will accept, or of recommended amplifier power. Just warnings about common-ground; and a warning that too little power is more risky than too much due to over-driving the amp. I've heard that the "max power" is 500 watts...but without reference to RMS, or long-term vs. peaks; or whether that's single-tone or wideband. In short...it's meaningless.

Typically when I see specs like "30--350", they're recommending an AMPLIFIER that is RATED for "30 to 350" watts; but amps ratings tend to be advertised most heavily at an 8-ohm load, and the SDAs are typically a lower ohm load. A QUALITY amp rated at 350 watts/8 ohm is likely to put out considerably more into 6 or 4 ohms; and then there's the matter of short-term dynamic power which is greater than the FTC rating.

Max power for your speakers is likely to be determined by when your ears hurt or neighbor complaints as much as by wattage levels.

heiney9

For reference this is from tests for the SDA 1C

See page 46 the far left paragraph above the cartoon. An 800 watt amp ran out of power before the speakers distorted. One of the most powerful amps of that era.

http://www.polksda.com/sda1creview.shtml

This is not to be taken in absolute terms, but to show that with good clean power you will probably be blown out of a typically sized listening room before the speakers reach their limits.

H9

gmcman

Schurkey wrote: »

Typically when I see specs like "30--350", they're recommending an AMPLIFIER that is RATED for "30 to 350" watts.

Correct, that's how I see it also. I just don't know what the specs are for the 2B, thanks Jesse for that.

I wan't sure if the 350 Watts was MAX or continuous (RMS)

I will be using a Yamaha MX-1000 which is rated at, in RMS:

•260 Watts (8 ohms) from 20 to 20,000 Hz at no more than 0.003% Total Harmonic Distortion.
•295 Watts (6 ohms) from 20 to 20,000 Hz at no more than 0.007% Total Harmonic Distortion
•330 Watts (4 ohms) from 20 to 20,000 Hz at no more than 0.02% Total Harmonic Distortion

Dynamic power @6 Ohms is 560 WPC, but i'm going by RMS.

Also current is a large factor and the MX has a decent flow.

heiney9

The Yammy is respectable, but certainly nothing to write home about, IMO. You will blow something if you you take those manufacturer specs to heart and start cranking stuff. Actually those ratings are pretty weak. A really great push/pull amp will either double down or come close to doubling down when the impedance is halved. Dynamic power means nothing as you have no idea how that number was derived. Many times that number is achieved by performing some kind of test that would never occur in real world use, so it's essentially meaningless.

The Yammy will be fine, but it will give out long before the speakers will and you will end up damaging the speakers when you overdrive the amp. Watts don't really mean much beyond reaching a high SPL.

Schurkey

gmcman wrote: »

I wan't sure if the 350 Watts was MAX or continuous (RMS)

I think you're misunderstanding RMS power.

RMS has to do with AC voltage rather than "continuous" power. Amplifiers have an RMS power spec based on continuous power at a certain distortion level, but it's expressed as RMS power because it's an AC voltage, not because of the long-term (continuous) nature.

Dynamic (peak) power could also be expressed as RMS if measured with an AC output.

gmcman wrote: »

I will be using a Yamaha MX-1000 which is rated at, in RMS:

•260 Watts (8 ohms) from 20 to 20,000 Hz at no more than 0.003% Total Harmonic Distortion.
•295 Watts (6 ohms) from 20 to 20,000 Hz at no more than 0.007% Total Harmonic Distortion
•330 Watts (4 ohms) from 20 to 20,000 Hz at no more than 0.02% Total Harmonic Distortion

Dynamic power @6 Ohms is 560 WPC, but i'm going by RMS.

Also current is a large factor and the MX has a decent flow.

You'll be fine.

gmcman

Schurkey wrote: »

I think you're misunderstanding RMS power.

RMS has to do with AC voltage rather than "continuous" power. Amplifiers have an RMS power spec based on continuous power at a certain distortion level, but it's expressed as RMS power because it's an AC voltage, not because of the long-term (continuous) nature.

I actually am misunderstanding somewhat...but that makes more sense.

I agree there are better options than the MX-1000, but it surely will do better for the 2B's than my Denon 3300.

Schurkey

heiney9 wrote: »

A really great push/pull amp will either double down or come close to doubling down when the impedance is halved.

Takes an ENORMOUS power supply to do that when going from 4 to 2, and from 2 to 1 ohm; at least with conventional Class A/AB output device operation. Most amplifiers don't have the copper or the capacitance. Those that do, tend to be expensive. The huge power supply is part of what makes them "really great".

heiney9 wrote: »

Dynamic power means nothing as you have no idea how that number was derived. Many times that number is achieved by performing some kind of test that would never occur in real world use, so it's essentially meaningless.

Exactly the same as the "crazy" ampere specifications given by far too many amplifier manufacturers. If the amplifier maker is claiming 40, 60, 100 amperes of current flow, ASK THEM FOR THE TEST PROCEDURE PROTOCOL. They won't give it to you; because the protocol involves driving a dead short for a microscopic length of time--musically insignificant. It's a LIE based on "meaningless truth"; and if the FTC wasn't corrupt, they'd put an end to it.

heiney9 wrote: »

Watts don't really mean much beyond reaching a high SPL.

THANK YOU.

I got my **** handed to me for suggesting that some time ago...

(To their credit, I didn't do a good job of explaining myself.)

inspiredsports

The 1987 literature that came with mine shows 10-500wrms

Joe08867

The rating on my 2B's was 10-500watt. But like someone else said there is more to it than that. Clean watts can be up to the 500watt point. As far as the Yammie is concerned I would keep my ears open for clipping. It isn't a bad amp but it also isn't the best amp for SDA's.

PreCd

I am using a Adcom GFA-555 and it works very well driving the 2Bs. Used you can snag one for $300 that is in working order. Be sure to ask what the offset voltage is at the speaker out terminals. If below .050 vdc then get it.

F1nut

The 1987 literature that came with mine shows 10-500wrms

The rating on my 2B's was 10-500watt.

That's interesting as those are the ratings for the 1B's. All the Polk literature I have, including the 1989 owner's manual, states the 2B's are 30-350. I have to think Polk had yet to update the info provided with the 1987 2B's.

stone of tone

It doesn't matter if your listening to ten or a hundred watts, the most dynamic range occurs in the first watt of playback. It calculates out to around 30dB of dynamic range in the first watt. The second watt adds another 3 dB. The power must be doubled for each 3dB of increase. In audio, power comes with diminishing returns.
A typical noise floor in a small apartment is around 45dB during the day. The softest tone the human ear hears at 1000 Hz is about 5 dB. (a tone that is just audible at 30 Hz must be a at least 60 dB.)

You might think there is a huge difference between a 2 watt Zen triode amp and say a 120 watt solid state amplifier but in reality its only 20dB difference. On a 100 dB efficient speaker, 2 watts is 103dB and the bigger amps 128 watts is 121 dB. If you set the volume dial for a peak level of 100 dB (way louder than the average listening level in the home) there is no difference between the 2 watt amps and the 120 watt, 250 watt, or 40,000 watt amps. Gotta have that extra 20 dB of dynamic range, turn down the noise floor - listen at night. This will sound far superior to the same dynamic window during the day with a larger amp since there is 20 dB less ambient noise polluting the sound you hear.

For what it's worth.

F1nut

One of the problems with your statement, 2 watts won't even wake up a pair of SDA's. Nice try though.

stone of tone

Apparently you have never listened to a Zen Select 2 watt Amplifier. IT will drive a 6, 4 and 2 ohm load too. Pentodes run in Triode.
I comfortably listen at 76 to 84db SPL with this Amp WITH MY SDA 1's. The soundstage, tone and timbre, image specificity and holographic imaging will beat any solid state Amp under 20k. Bold statement, but true.

What is the catch? Well, I can't run the SDA function with this Amp and the average SPL can't exceed 80db as described, without compression and then to clipping. However, the preceived/subjective loudness with this Amp sounds louder and all so musical. NOW my Torii MK III, can run the SDA function with great musicality as described from the Zen Select but with even more authority.

SO, nice try Listen grasshopper before saying what you said.

Oh, PS.....if your listening above 90db SPL in your home......your not listening......your having a dynamic range pissing match with your friends weeeeeee......you should have grown out of that stage with the boom boom car stereo years ago............ .

F1nut

The soundstage, tone and timbre, image specificity and holographic imaging will beat any solid state Amp under 20k. Bold statement, but true.

And this you know because you actually owned anything close to a $20k SS amp. LOL

Well, I can't run the SDA function with this Amp and the average SPL can't exceed 80db as described, without compression and then to clipping.

Otherwise known as an epic fail.

Keep digging your hole little boy, it amuses me.

stone of tone

Ah yes, I have heard 20k solid state. Audio Research is in my back yard and I have spent a few listening sessions in their rooms with the Audio Society of MN.....and at Magnepan where I used to work. Got you rattled little boy didn't I.

Epic fail? Reading comprehension, selective reading on your part? The MK III as stated is glorious with SDA.

Hole digging? Your the one being laughed at right now all over this site........... . It is only after 11 for my CAL friends chuckling right now!

Joe08867

OK, So we have someone new to add to the Bozo list. It's always good to come in acting like you know when you haven't a clue. Good luck with that SOT.

F1nut

Ah yes, I have heard 20k solid state.

That's not what I said. I said that you have not owned anything close to a $20k SS amp. Of course, that means that you have not listened to your SDA's on any such amps. Therefore, your comment is completely without merit.

Epic fail? Reading comprehension, selective reading on your part? The MK III as stated is glorious with SDA.

Odd comment, since the both of us were talking about your Zen Select 2 watt Amplifier. Hello!


You are obviously trying to act like you know something that in reality, you don't and therefore lack credibility. On the other hand, my knowledge/credibility is well established, so it matters not what you think of me. I'm not the one trying to get into big boy pants, but I wish you luck with that.

FYI, your SDA 1's with that weird SDA tweeter issue and lack of refinements are the least desired of all SDA's.

inspiredsports

stone of tone wrote: »

It doesn't matter if your listening to ten or a hundred watts, the most dynamic range occurs in the first watt of playback. It calculates out to around 30dB of dynamic range in the first watt. The second watt adds another 3 dB. The power must be doubled for each 3dB of increase. In audio, power comes with diminishing returns.
A typical noise floor in a small apartment is around 45dB during the day. The softest tone the human ear hears at 1000 Hz is about 5 dB. (a tone that is just audible at 30 Hz must be a at least 60 dB.)

You might think there is a huge difference between a 2 watt Zen triode amp and say a 120 watt solid state amplifier but in reality its only 20dB difference. On a 100 dB efficient speaker, 2 watts is 103dB and the bigger amps 128 watts is 121 dB. If you set the volume dial for a peak level of 100 dB (way louder than the average listening level in the home) there is no difference between the 2 watt amps and the 120 watt, 250 watt, or 40,000 watt amps. Gotta have that extra 20 dB of dynamic range, turn down the noise floor - listen at night. This will sound far superior to the same dynamic window during the day with a larger amp since there is 20 dB less ambient noise polluting the sound you hear.

For what it's worth.

I think you are getting caught up in the db game, but my/our comments are related to sound quality.

I rarely listen above 85db (with 92db 1w/1meter speakers).

You can certainly generate high db levels with just a watt or two, but that's not the full story.

I'm not advocating watts either and loathe so-called "Pro" gear, but the OP did ask about power handling capability.

At any rate, specs in the proper context are an important indicator, but sound quality is what most of us here are about, and SDA's thrive on high quality, high current watts and reward you with high sound quality when properly fed.

Did you really say your amp can't handle SDA's with the interconnect connected ?????

sda2mike

i know jack about db's...i do know that my adcom gfa555 drives my 2b tl's to levels that are loud and clear..i'm careful because the adcom doesn't have speaker protection...also the speaker protection in the speaker was eliminated...even so, the level i don't exceed, abt 10 o'clock, is loud enough in my room, that i can't hear myself snap my fingers! the 2b tl's seem to 'blossom' at that power dosage

inspiredsports

sda2mike wrote: »

i know jack about db's...i do know that my adcom gfa555 drives my 2b tl's to levels that are loud and clear..i'm careful because the adcom doesn't have speaker protection...also the speaker protection in the speaker was eliminated...even so, the level i don't exceed, abt 10 o'clock, is loud enough in my room, that i can't hear myself snap my fingers! the 2b tl's seem to 'blossom' at that power dosage

Just a few cautions.

Decibel level isn't the whole story.

You could create highly distorted or clipped signal that could destroy a tweeter at a decibel level that's lower than you might think.

Also, relative clock position of a dial has very little to do decibels. Every piece of equipment is different. Distortion and clipping are the culprits you need to be aware of.

sda2mike

good points...i know, it's all relative...just my system..i have a 'bias' adjustment on my pre..i'm conservative with that...as far as distortion; i hear nothing but sweet music...if, and i'm on watch, trust me, if i hear anything, i'm outta my chair like a bullet! my mw's are just barely dancing..compared to sal's video, mine are doing fine

thanks
mike

heiney9

sda2mike wrote: »

i know jack about db's...i do know that my adcom gfa555 drives my 2b tl's to levels that are loud and clear..i'm careful because the adcom doesn't have speaker protection...also the speaker protection in the speaker was eliminated...even so, the level i don't exceed, abt 10 o'clock, is loud enough in my room, that i can't hear myself snap my fingers! the 2b tl's seem to 'blossom' at that power dosage

Yes, but your 555 should have the distortion lights that flicker. While that is good to watch by the time those lights are full on the damage is already done. Once they just start to flicker at the peaks of the music you are essentially at the clean limits for the particular music you are playing.

sda2mike

heiney9 wrote: »

Yes, but your 555 should have the distortion lights that flicker. While that is good to watch by the time those lights are full on the damage is already done. Once they just start to flicker at the peaks of the music you are essentially at the clean limits for the particular music you are playing.

that's right! i've never seen those lights blink or flicker, ever...i'm sure if i had this setup when i was 22, i would have fried some parts..

PreCd

sda2mike wrote: »

that's right! i've never seen those lights blink or flicker, ever...i'm sure if i had this setup when i was 22, i would have fried some parts..

Me too! I do listen loud at times but rarely above 10:30 or 11 o'clock on the dial.

By the way I just finished recapping my GFA-555 last night and it changed it dramatically. Did not touch the filter caps but replaced the four on the PCB. Have almost all my caps in for my GFP-565 and will get to the fifteen caps in that this weekend.

sda2mike

PreCd wrote: »

Me too! I do listen loud at times but rarely above 10:30 or 11 o'clock on the dial.
By the way I just finished recapping my GFA-555 last night and it changed it dramatically. Did not touch the filter caps but replaced the four on the PCB. .

cool! i've been thinking about tackling this project..i'm a complete novice at this type of repair...while working on the board, did you need to de-solder the leads going to the board? or are they long enough to flip it around? how did the sound change, btw?

i think we mighta derailed op's thread...pm me when you can

thanks
mike

inspiredsports

sda2mike wrote: »

good points...i know, it's all relative...just my system..i have a 'bias' adjustment on my pre..i'm conservative with that...as far as distortion; i hear nothing but sweet music...if, and i'm on watch, trust me, if i hear anything, i'm outta my chair like a bullet! my mw's are just barely dancing..compared to sal's video, mine are doing fine

thanks
mike

And I wasn't so much speaking directly to you, but future new members who might read and not understand that if you are going for high power, it has to be HIGH QUALITY power with LOW DISTORTION to make SDA's sing without blowing something up.

sda2mike

inspiredsports wrote: »

And I wasn't so much speaking directly to you, but future new members who might read and not understand that if you are going for high power, it has to be HIGH QUALITY power with LOW DISTORTION to make SDA's sing without blowing something up.

oh yeah!! DON'T DO THIS @ HOME WITH YOUR RECEIVERS, KIDDIES!!