klipschorn speaker impedance

[sasqwatch]

If understand correct they are 8ohm but the impedance varies with frequency.what I would like to ask .I am thinking of bridging my amps so they are 400 watt mono.but to do that the amp has a impedance selector that has to be switched to 4 ohm.will it still be safe to run my klipschorns with it running at 4 ohm (with some self control with the get loud knob) thanks for any insight .

[Don Richard]

What amplifiers do you have?

What year are your Khorns?

Why are you wanting to throw 400 watts into a Khorn?

[garyrc]

400 wt. mono into each Klipschorn? How big a room do you have, and how far away are the listeners? 400 wats is potentially lethal to your Khorns if anything ever goes wrong ... I know they are rated at 100 wts, with 400 wts peak, but the peak they probably have in mind is ultra, ultra brief and devoid of treble. The highest reading I ever got from peak reading meters into my Khorns was 25 wts per side for house warping loudness. Once, someone else got a flicker out of my meters that may or may not have shown 60 wts for a split second. 1/10 of that (reading 6.3 wts) is gargantualy loud.

[sasqwatch]

What amplifiers do you have?

What year are your Khorns?

Why are you wanting to throw 400 watts into a Khorn?

the amps are nad 2700thx the khorns are 1988.I'm New to this hobby so correct me if I'm wrong,I thought by having tons of extra power gave me more headroom .witch in turn sounded better .thanks for the reply .

[sasqwatch]

400 wt. mono into each Klipschorn? How big a room do you have, and how far away are the listeners? 400 wats is potentially lethal to your Khorns if anything ever goes wrong ... I know they are rated at 100 wts, with 400 wts peak, but the peak they probably have in mind is ultra, ultra brief and devoid of treble. The highest reading I ever got from peak reading meters into my Khorns was 25 wts per side for house warping loudness. Once, someone else got a flicker out of my meters that may or may not have shown 60 wts for a split second. 1/10 of that (reading 6.3 wts) is gargantualy loud.

the room is small 15z20 my seat will be around 15 feet from speakers I dont listen to loud volumes very often once in a while for merry shot times I may not understand headroom but I thought having surplus power would give me extra headroom and sound better .thanks for your reply

[Islander]

If you're careful with the volume control, you won't damage your speakers. There's a big difference between "driving your speakers with 400 watts per channel" and "having 400 watts per channel available to your speakers", as in continuous power versus momentary peaks.

If you're listening at sensible volume levels, the extra headroom available may improve the dynamics and the realism of the sound. Doubling the power only increases the volume by 3 dB, and that assumes there's no dynamic compression. It's worth a try, in my opinion anyway. Bridging the amps may change their sound and make it worse instead of better, but that's not certain, and you won't know until you try.

Let us know how it works out.

BTW, the impedance control on the amps may not be a helpful feature. In the case of certain AVRs, changing the impedance switch setting from 8 ohms to 4 or 6 ohms limits the amps' rail voltage, reducing bass output and causing thin sound. Google "Yamaha impedance switch" and you can find out lots about that.

The impedance switch is a feature meant to ensure that the amps never run too hot, even when driving low-impedance speakers at high volume. However, if your amps have enough space around them to allow cool air to enter and hot air to leave, and you're not running them at constant dance-club volume levels, there should be no problem with leaving the impedance switch in the 8 ohm position.

[Don Richard]

the amps are nad 2700thx the khorns are 1988.I'm New to this hobby so correct me if I'm wrong,I thought by having tons of extra power gave me more headroom .witch in turn sounded better .thanks for the reply .

100 watts will drive 1 Khorn to about 125 dB SPL, about 128 dB for 2 of them. That's what a bar band's PA puts out. Is that not sufficient?

[sasqwatch]

Yes 128db is way above my listening level .like I said I was wondering if the surplus power would give me a better sound quality.not that the k horns sound bad .

[sasqwatch]

Thanks for the reply islander ill look into the impedance switch on the amps.probably call nad next week to see what they say about leaving them set to 8ohm.the manual says to switch it to 4 ohm if they are bridged.even if they are to be used on 8ohm speakers.i just bought the second amp today so I wont get it till late next week.may get to try the two amps bridged next weekend. I will let you know how it works out .thanks for the input.

[derrickdj1]

The thing about excessive power is that it is just excess and will not improve SQ and just go unused.

[garyrc]

If you're careful with the volume control, you won't damage your speakers. There's a big difference between "driving your speakers with 400 watts per channel" and "having 400 watts per channel available to your speakers", as in continuous power versus momentary peaks.

I agree that, with care, using a 400 amp with Khorrs won't hurt, but it would make me nervous, in case mistakes are made. Someone (kids? The inebriated?) could have the volume turned way up when the amp is off, and it could come on loud. The classic old mistake was accidently dropping a needle on a record. Paul Klipsch used to recommend putting fast blow fuses in line with the speakers, but we modern purists don't do that.

Sasqwatch, since you say you are new to the hobby, I'll point out that with the most conservative figures I've ever seen (not the Klipsch rating), the Khorns produce 98 dB at 1 wt at 1 Meter. Compared to a typical speaker, which produces about 90 dB @ 1watt @ 1M (generous!), 100 watts into a Khorn is like about 666 (the devil, you say) watts into that typical speaker. 400 watts (for rare peaks) into a Khorn would be like about 2,664 watts into the typical speaker. If we take Klipsch's figures (based on the Khorn being sealed into a trihedral corner with at least 4 feet of uninterupted wall space on either side) of 105 dB @ 1 watt @ 1 Meter, we find that 100 watts into a Khorn is like 3,200 watts into a typical speaker. 400 watts into a Klipschorn would be like 12,800 watts into the usual speaker!

Headroom is nice, but you already have that. It's true that bridging amps may produce better or worse sound. If you had a huge room (like 10,000 cubic feet), or were outside in a park, or open field, I could see bridging your amps, but for that kind of application, you would probably have a bank of speakers of Klipschorn efficiency. I saw such a bank one time, as wide as the end of Haight street. People were on their hands and knees staring at the ground. I investigated, with my ears plugged. The dirt on the sidewalk was bouncing up and down in time with the beat! Bands like that carry spare speaker parts -- even with a bank of speakers to divide and absorb the power, there are risks. JBL once ran an advertisement that stated that a band set up and left such a bank (of JBLs, naturally) and a passing griffen coughed into the microphone, leaving nothing but a crater.

[WMcD]

I think this is fruitless project. You certainly don't need 400 watts potential. You will be listening at 4 watts max.

To explain what is going on with the setting of bridging.

When you set to bridging, one amp output is reverse polarity output from the other. So if one is putting out 10 volts plus at the red terminal of the left output, the other is putting out 10 volts minus, both relative to ground.

Let us assume that you have an 8 ohm speaker (resistance) which the amp "likes" when connected from either red to ground.

But this can be considered as two 4 ohm speaker (resistance) in series.

Now, you connect it across the two red outputs of the "bridged" amp we see that we get:

(+ 10 volts) left output at red - - 4 ohms resistance-- center junction (zero volts) -- 4 ohms resistance -- (-10 volts) right output at red.

This explains what is going on with a stereo amp where bridging seems to give four times the power when bridged mono. You are using both sides of the stereo amp (makes sense for doubling) but also each amp is "seeing" half the resistance (which doubles current draw and power if the power supply of the amp can deliver, often not true).

You have to take a close look at the diagram. The center junction is at zero volts which is the same as ground, a virtual ground. Therefore each amp is "seeing" a 4 ohm load, even though the speaker / resistance is 8 ohms.

The advice to set the amp control to 4 ohms makes sense in view of the above, which assumes 8 ohm speaker.

The problem is that the K-Horn's resistance drops to 4 ohms at some freqs and by bridging, you're presenting either amp with 2 ohms. The power supply of the amp probably can't deliver into 2 ohms and distortion from the amp is higher.

WMcD

[sasqwatch]

WMcD thanks for taking the time to explain amp bridging and its relation to resistance.what I was thinking to accomplish was to gain extra headroom and maybe improve the sound. Although the amp is supposed to be stable to two ohm it has a rms of 150 watts per channel ,which is probably a lot of headroom to start with. If I do bridge them it would just be a short run to see if there was any difference in sound. Thanks again for your time and knowledge. Stacy

[ZAKO]

There will be no difference in sound,,,But you might smell smoke..

[Mongo171]

But you might smell smoke..

I'll bring the marshmallows! [Y]

Might bring a fire extinguisher if he plays it loud! [N]

[Deang]

Bridging sounds terrible, don't do it. Also, your headroom is built into your loudspeakers, it's called "efficiency". Quantity does not always equate to quality, especially in this case. The NADs sound nice - adding power by bridging will be a step back in sound quality.

[DizRotus]

I don't recommend it.

in the 70s, I drove four 8 ohm Speakerlab SKhorns (2/channel in parallel for 4 ohm load) with a Dynaco ST-400 (300 watts/channel into 4 ohms). I was filling gymnasiums with very loud music.

Since then, I've powered Khorns, LaScalas and Cornwalls with as little as 11 watts/channel. Quality is better than quantity.

Bridging your amp won't make Khorns sound better, IMO.

[sasqwatch]

Thanks everyone for your input ,the general consensus bridging my amps would have no benefit and is potentially fatal for the beloved khorns.so I have decided to not peruse the bridging . This is another example of the fine people of this (klipsch community) sharing their experience and knowledge. Stacy

[garyrc]

.i just bought the second amp today so I wont get it till late next week.may get to try the two amps bridged next weekend

Since it sounds like you already ordered the second amp, if you don't or can't cancel the order, consider using the extra amp to add channels to your music listening system. The 4 (two surround), 5, or 5.1 channels available with SACD really add musicality to some of my disks (but fail to improve others), IMO. Streaming pure DSD just became possible (see the current, July 2013, Stereophile magazine, page 49), and pure DSD is reputed to be even better than the SACD disks it is used to author, if the disks must be converted to hi rez PCM by home equipment, as they must be at my house. Streaming pure DSD could be revolutionary. As to SACD, even those who don't hear a difference between the SACD format and CD, usually acknowledge that -- if well done -- the extra channels provide more dimentionality. I have Khorns in the front, and, with SACD, switching on the Belle Center and Heresy II surrounds often improves the audio without seeming to degrede the purity of the music from the Khorns. Sometimes not. Any benefit seems to hold even on those SACDs without a center channel.

I wouldn't even try the bridging, I'm not sure whether the posts about danger are for real or humor, or both, but I am sure that my NAD 150 w.p.c. power amps provide incredible headroom. I think that the truth of the matter is that: 1) bridging may make sense only with normal or inefficient speakers that need 7 to 6,000 times the power that your Klipschorns require2) bridging may sound worse with some speakers 3) There may be some danger with some speakers.

[RRFL]

Thanks everyone for your input ,the general consensus bridging my amps would have no benefit and is potentially fatal for the beloved khorns.so I have decided to not peruse the bridging . This is another example of the fine people of this (klipsch community) sharing their experience and knowledge. Stacy

A.There is something that has not been considered here and that is to use 1 amp per speaker using on 1 channel of each amp. This gives the full capacity of the power supply in each amp to the single channel driven. This can only improve the performance of the amps.

B. Also there is the possibility of adding an electronic crossover into your system so that you can time align the high frequency horns more closely to the folded horn woofer. In this case I would suggest using 1 amp per speaker and using the left channel for the woofer and the right channel for the high frequency horns. Again the power supply would have more available for the woofer where it needs the most as the high frequency horns draw only a small amount. Using the amps in this way makes setting the crossover simpler as the amp sensitivity is the same for all 4 amp channels.

I assert that the improvement with A. would likely be minimal with the quality of the amps you are using, however it's generally the power supply that is the limiting issue with amplifiers.

I assert the the improvement with B. would likely be in your transient response where the high frequency click of the bass drum is better syncronized with the low tonal quality of the drum and have it sound more life like than it already does. This has a flow on effect for everything else that has frequencies spread across this crossover point.

Rod

p.s. to take this a step further you can take the tweeter out of the cabinet and make a small support for it to sit on top of the cabinet so that the tweeter magnet is directly above the midrange magnet. This gives physical time alignment between this pair of components.

Having a pair of Heresy in the rear corners set up so each wall has a left and a right speaker is also a very pleasing result. I did this often back in the 70's in the HiFi shop that I worked in.