Upgrade to ??

[bvk_houtx]

I currently have Klipsch RF3-II, RC3-II, RS3-II powered by a McIntosh MHT100 receiveer ( 100 watts x 8 channels, 4 ohms). I would like to upgrade to a 3 way speaker system. I was looking at the Klipsch Heritage line but my wife likes the looks & sound of the B&W 804S & 803S. I like the sound of the B&Ws but I think I would need an amplifier upgrade to go along with the speaker upgrade. My questions are is my current receiver a good match for anything in the B&W 8xx line? If not the 8xx, maybe the 7xx? My usuage is 75% movies & 25% music. My music tastes are varied, R&R, Country, Classical. Thanks in advance for any feed-back.

[audioqueso]

The 700 series sound is closer to the Klipsch RF line. The 800 series is a completely different sound, you know that right? Your receiver will PLAY the 804/083, but will really not bring them out to their fullest. You could probably get away with the 805 bookshelf, but for anything higher you'll probably want to get an amp eventually. The 700 is a lot easier to drive and can be done with the receiver.

[Karma]

HI audioquesto,
Your satement about the 700 series being much easier to drive than the 800 series got me wondering. You see, I think the 800 series are very easy to drive but I am not familiar with the rest of their product line. The entire 800 sereis except the 805 has a sensitivity rating of 90dB. That is a moderately easy drive in my book especially when compared to many speakers on the market that are rated around 85dB. Among audio pro's, B&W speakers have always had a reputation for being easy to drive.

So I took a look at the specs on the B&W site and found the published specs for the 700 series to be essentially identical to the 800 series. They are sensitivity rated at 90dB.

With all respect for your views, I don't see the basis for your statement. To be fair I have seen others make the same statement. Is this another urban legend? Or do you have knowledge that goes beyond second hand opinion that we should know about? Inquiring minds would lke to know.

Granted, the sensitivity spec does not tell the whole story for any speaker. There can be impedance anomalies that can drive amplifiers nuts that do not show up on the sensitivity number. But, when comparing speakers, the sensitivity spec is the usual way one compares different speakers for amplifier compatability.

Sparky

[RebelMan]

To be fair I have seen others make the same statement. Is this another urban legend? Or do you have knowledge that goes beyond second hand opinion that we should know about? Inquiring minds would lke to know.

It's not an urban ledgend, just plain ole' physics at work. Power can be expressed in a number of ways. In one way it can be expressed as the product of current and resistance (impedance). In another way it can be expressed as the product of voltage and the "inverse" of resistance (impedance). To deliver the same power as impedance drops, current would have to increase in the first case and voltage would have to decrease in the second case.

Speaker sensitivites are voltage driven and speaker impedance curves are current driven. A speaker with high sensitivity requires less voltage to drive and thus less power. On the other hand, a speaker with low impedence curves requires more current to drive and thus more power. Judging the demands that a speaker places on an amplifier by sensitivity alone will only tell part of the story. You need to know what the impedence levels are as well.

This is why some B&W 800 series models with high sensitivies can be difficult to drive.

[Karma]

HI Rebel,
Impedance is certainly a key issue and a very complex (pun) one. The specified impedance value for any given speaker is, as you know, an average over the specified frequency range. All B&W's are specified as 8 ohm speakers. The deviation from the average can usually only be discovered through testing since most manufacturers do not specify it.

The value will vary some from this average especially at the crossover points (we come back to that subject again 8) ). Impedance also drops on conventional magnetic speakers as the frequency is reduced in the bass frequencies. On electrostatic speakers the situation is reversed with the impedance reducing as frequency in increased in the high treble regions.

These are the the simple facts. However, they do not, a priori, expalin why the 700 series speakers are easier to drive than the 800 sereis. So far, I'm not buying into the legend because I still don't see the evidence.

BTW, sorry to say that impedance is not the inverse of resistance. Rather, it is the AC reactive equivalent of resistence. If the F (frequency) term in the reactance equations is equal to zero (is DC), resistance and impedance are equal.

Sparky

Edited to remove an incorrect conclusion and irreverant reference which further posts showed had no basis in truth. This edit did not change the content of the main subject of this post.

[Gump]

When I used to run my 604 speakers at high volume for extended listening periods the cooling fan on my Marantz SR-8200 receiver would kick on leading me to believe the receiver was working hard to maintain that level of performance. Since I've had my 803D's the Marantz's fan hasn't kicked on once and I've cranked the daylights out of it for extremely long listening sessions. This leads me to surmise that the 803D's are very efficient speakers and easier to drive than the 604's. (and no, I don't believe the fan is broken!)

That being said, I'm obviously not getting the peak performance from the speakers with this receiver and I'm still shopping for the ideal amp....

[RebelMan]

BTW, sorry to say that impedance is not the inverse of resistance. ... This misinformation is how urban legends are born. We always need to guard against this.

I never stated that impedance is the inverse of resistance. It was stated that power is inversely proportional to resistance (aka impedance) when expressed in terms of voltage.

In DC circuits impedance is simply resistance. In AC circuits impedance is composed of capacitive reactance and inductive reactance in addition to resistance. Capacitive and inductive reactance are functions of frequency that varies with time. These changes in frequency, in addition to the construction and components used in the crossover network, will in turn dictate the load the amplifiers see at a given point in time. When these loads are sufficiently high, i.e., of low impedance, and they occur with some regularity the current neccessary to satisfy the demands of the speaker goes up.

Perhaps some mathematical examples can illustrate the point further and dispell your urban belief that this is misinformation? Though, if you had an education in electrical engineering it would be moot, you would believe.

[RebelMan]

Gump, did anything else change in your system? Are you using the same room, the same equipment (in the same location) and supporting speakers (surrounds, etc), the same cables, and the same listening habits (warmup, volume, position, etc)? Was the only thing that changed the 803D's and absolutely nothing else? If absolutely nothing else changed then your results would be puzzling as both the 604 S3's and the 803D's are rated about the same.

[Karma]

HI Rebel,
I do have an education in electronics. With your clarification I believe we are saying the same thing. I do understand AC theory. Shall we get into the "why crossovers are bad" discussion again from an impedance and phase angle point of view?

If you check, I edited out the legend reference but not the technical information which I believe is useful and consistent with you clarification. You are hereby removed from the Propagators of Urban Legends list. 8) . Sorry for the misunderstanding but I'm sure you agree that these terms are commonly misunderstood.

When I was running my repair shop I ran into this all the time from people that should know better. Sometimes I actually had to pull out my multimeter to demonstrate that the resistance of a voice coil was close to zero ohms and not the impedance value indicated on the speaker. Indeed, a common misconception.

Sparky

[Karma]

HI All,
Rebel and I have moved this thread into an area (speaker impedances and variations therein) where we can discuss speaker efficiency which is the point ot this thread.

Since we are working with anecdotal information it is really difficult to come to definite conclusions. Does anybody have access to B&W speaker impedance curves? A selection of models in the 700 and 800 range would be nice. But anything is better than nothing.

Sparky

Edited to Add: I am going to post this question as a main topic. Thanks all.

[Gump]

Rebelman,
Everything in the setup is ABSOLUTELY identical....
I gave this some thought and if pressed I'll concede that the volume level on the receiver may not have been consistantly quite as high with the 803D's as with the 604's. But this is due to the 803D's sounding so much "bigger" and "louder" at lower volume levels. The 604's had to be driven at higher volumes to get the same satisfaction from their sound. This may be unscientific logic, but to me this still indicates that the 803D's are "easier" to drive because less power was required to get the same level of enjoyable sound. And I assure you that they WERE being driven at extremely high levels with occasional extended periods equalling or surpassing the volume levels used with the 604's. (certain surround DVD's, Eagles, Clapton, Led Zepplin require mega volume! IMO).

If I'm bored one day I'll try to do a more controlled A/B with the 604's and see just exactly what it takes to get that Marantz's fan cranking!