HIII and CWIII 100 watt continuous power handling?

[Clarence]

I just checked out the continous power handling specs for my HIII's and the CWIII. Both are rated at 100w continuous, and 400w "peak".

I am considering a NAD 7600 reciever, based on the 2600A amp. This 2 channel reciever is 150wpc RMS and 500wpc peak with its "power envelope" technology. My question is will I be overdriving my HIII's with this reciever? I always thought that speakers were damaged by not having enough power and being driven into distortion. I want to be prepared when a 7600 comes up, so I am doing my homework now.

I plan on moving to CWIII's once I am in a better financial condition. I dont usually listen to music at extreme volumes, but have found myself cranking things like Metallica "and Justice for All" and love the HIII's punch with my 7100 reciever, rated at 50 WPC. Thanks for the advice!

Here is the info sheet on the 7600.. I also am including a pic, they make posts a bit more enjoyable...

http://207.228.230.231/info/NAD_7600.pdf

C

[Colin]

Two decades ago, I lived with a blue-gray solid-state Carver (M1.5t?) amp capable of 750-watt peaks per channel and walnut-oiled <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />Cornwall 1s, with B2 crossovers. The amplifier was capable of sustaining 350 watts RMS into an 8 ohm load with no more than 0.5% total harmonic distortion from 20 to 20,000 Hz. It pushed 600 watts per channel RMS into 8 ohms for musically significant periods. As for the power supply, the M1.5t is regulated to charge the output stages for a brief maximum of 1200 watts. The manual warns proceed gingerly in experimenting with the joyous undistorted sound levels the M-1.5t can drive them to. Amounts of [power] on the order available here can easily - unseat woofer voice coils, damage cone suspensions, char or fuse tweeter voice coils and even demagnetize driver motors..."!

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

The Carver units drove my super-sensitive walnut-oiled Cornwall 1s, with their B2 crossovers, like a diesel engine on a go-cart. Lots of raw power. Every once in awhile, we would tempt fate and turn up the volume in my small 100 year old New England home. The live cannon shots on Telarcs 1812 Overture smacked the floor, tickled the toes, raised dust, rattled windows, impressed teenagers and created a tsunami sound wave big enough to flatten Tokyo. You could feel it all right. Even with out a sub woofer, my Cornwalls had no problems with this unusual musical piece.

The combination of the two components however did not make music. At the low power levels that sensitive horns require, the Carver had copious amounts of THD. Carver's amps are NOT a good sounding or practical spending match with sensitive horns.

Solid-state amps, like the super powerful Carver I had once or the super clean Pioneer I have now, have tremendous amounts of Total Harmonic Distortion down in the micro-watt range. Their THD ratings are from the middle of their output curve, where THD is at its lowest, not the low end or the high end, where THD climbs like a rocket after lift off.

Unfortunately, as I learned from the insane posters on the Klipsch BBS, ultra efficient horns idle along on only a few milli-watts of power. Most of the time, they do not need all that much power. It is only for those rare microseconds of sonic shock, like the levered thump of the kick drum, that the speakers suddenly cry for instantaneous surges of hundreds of watts. But those microcosmic spikes soon pass and the speakers are idling along again with barely a push from the amp.

You don't need lots of power with Klipsch's big old horns - you need lots of good, clean power. Class A is good; tubes, in my own humble opinion, is better performance at a lower price, but with some learning required.

The more sensitive a loudspeaker is, the easier it is to couple it with an amplifier to provide the musical headroom. Twenty watts is all the power that most big ole horns need for many types of music in average size rooms. The lower the power requirements, the more important the quality of the FIRST FEW WATTS.

An amplifier with 10-watts Class A power is going to be running Class A almost all of the time. The Pass Laboratories Supersymmetry Balanced Single-Ended Class-A X250 Stereo Amplifier is designed to give you "Class A" quality below 75 watts (http://www.enjoythemusic.com/magazine/archives/). In fact, using the thunderous Pass X250 on a big old pair of Cornwalls Is, we never saw the needle in the single blue eye move into the Class A/B range, even with some painfully loud levels (>110--dB) and some pretty violent action scenes (The Matrix).

[Clarence]

Hey Colin, thanks for the quick reply.

I reread your post trying to draw a specific conclusion to my question. I think that I came up with "it wont be a problem as long as the amp section of the reciever has acceptable distortion specs."

Did you peek at the attatched sheet regarding the NAD's thd? I do not know how to tell a good thd rating from a bad. Does this amp have favorable distortion specs?

I also gathered from your post that the 100 watt continuous power rating on the Klipsch speakers in question is a conservitive estimate. Am I reading this right?

I appreciate the time you took on your post,

C

[Z4!]

THD specs are quoted at their best, which is usually at high power for SS amps, not at a watt or two (or below). If you contacted NAD's egineering department they may be willing to tell you what the THD is at a watt or less. []

[PrestonTom]

The discussion is absolutely correct.

It is very hard to ascertain what the "effective" levels of distortion will be (esp with an efficient speaker). THD (usually at near max output) is provided, but it is usually not specified at levels between a half watt to a few watts. Trying to determine IM levels and transient IM levels is even more difficult.

That is why I always encourage folks to try out various amps before buying. This is especially true if you are using efficient speakers. My K-Horns seem to reveal everything...

Good Luck,

-Tom

[djk]

The NAD 2600 is a bright sounding amp that has no real high end. Edgy comes to mind. It is very lean in the low end. It also can eat Cornwall woofers if you crank it hard. That amp destroyed more Klipsch woofers than any amp I can think of. It can tear the voice coil clear off the apex of the cone. Of course if you don't crank it up, you won't have this problem.

An amp like an Adcom 555 sounds better balanced, and doesn't destroy woofers when cranked.

If a Carver amp sounds bad at low volume, it needs the bias adjusted. The old M1.0T was one of the best sounding amps on Klipsch that I heard that was reasonable priced.

30 years ago Yamaha receivers were rated at less than 0.1% distortion from 20hz~20Khz from 100mW to full power. They all exceeded this specification, I know because I ran the amplifier clinics and confirmed it.

The main reason SS amps sound bad is electrolytic coupling caps. Tube amps always use film types. Adding film bypass caps to electrolytic coupling caps is always a revelation. The same thing goes for adding power supply bypass caps. For the end user (that's you), we're talking about adding $4 worth of parts.

[colterphoto1]

You are less likely to blow stuff up with a bigger amp than a smaller one. Reason why- you wont send the amp into clipping. It is the distorted signal from the amp that tends to toast tweeters. (say three times fast).

So crank it up. But if it starts sounding distorted, you're blowing stuff up. I try to stay at -10db on my receivers so as to always have some headroom for peaks, as a general rule.

Michael

[oldbuckster]

Interesting, let me ask this; Aren't you better off using a higher powered amp/pre amp with the tone controls set at flat, as apposed to less power with the tone controls turned up?H2/3's and Cornwalls2/3's won't they kick-off if driven to clipping?It also seems to me that SS needs more power to sound the same as a lower powered tube set-up at the same volume setting?I don't know, just asking, seems to tie in with original question.

[stormin]

Nad 2600 and Nad 7600 use the same amplifier section.

[sheltie dave]

Clarence, you like NADs a lot(well, if you're a guy, everyone kinda likes their own, IYKWIM,) so I'll let you draw a few conclusions about their quoted specs.

If this NAD has only one power transformer, then ALL the power for both channels is being supplied by that one transformer. In the past, NAD has built a huge advertising campaign out of their reknown soft clipping, power envelopes, and instantaneous output levels.

If this 150 wpc can actually put out 500 watts instantaneous, how much is the other channel driving? Why is there no set of specs quoted for both channels at the stated instantaneous 500 watts peak for one channel? The likely scenario is you have a 3 dB headroom design, so there is a max of 600 watts total to play with. The current limit is set so only 500 watts instantaneous peak can be delivered with either channel at one time. There are very few musical stretches that will require a 5:1 channel output ratio....ie a lousy stereo recording.

If you want to pour some serious watts on a continuous basis through your Klipsch, you may consider some actual commercial power amps that have dead solid rail voltage to deliver the goods, ie Crown, QSC, and Bryston. They all have similar chain saw effects with Klipsch at/past certain levels for most people.

The thumbrule I use for desired power is a multiplier schedule - 10 for classical, five for jazz, and three for rock recordings. In order not to clip a signal, just divide your rated wpc RMS by the multiplier, and the only clipping/compression you may hear will be on the source.

For a 200 wpc amp, run the amp at 20 wpc continuous and the +5 to +8 dB normal peaks will cause no problems. Most jazz albums are also recorded with minimal compression, but rarely contain the wild dynamic crescendos like classical music, so you would expect 40 wpc continuous to work fine. Most rock music is severely compressed, so it holds the least dynamic range on average.

Sometimes more is less, when it comes to distortion, clipping, and blowing quality speakers. If you start pushing the envelope with that NAD home amp, you'll end up blowing the tweeter on the channel with the LOWER instantaneous peak. Been there, done it. I don't like that power borrowing scenario, because the manufacturer never details what may happen.

If you routinely run your amps at or above 50% rated continuous power, you may think about getting a new amp before your speakers tell you to do so.

[Clarence]

thanks for the great information!

about my listening habits: Never past mid dial, if ever slightly past is as hard as I will run an amp, I never would consider clipping my amp or damage to my speakers. Now that job is being handled well by a 50wpc NAD 7100, and it is doing a phenominal job. I am still toying with the idea of putting together NAD seperats, and the offer the amp section in 3 flavors 2100 for 50wpcx2, 2200 for 100wpcx2 and 2600 150wpcx2. IIRC.

"The 7600 is rated at 150 watts/channel for continuous test tones, but its Power Envelope circuitry produces much higher levels of tone-burst power for music. Even with compressed recordings of rock music in which the peaks are only a few dB higher than the aver-age power, the 7600 maintains a clipping level above 500 watts per channel into the complex 4-ohm impedance that is typical of real loudspeakers. In bridged mode a 7600 matched with a 2600A will deliver nearly 3000 watts of dynamic power into a pair of such speakers."

So there is where the bear shits in the woods. I have provided my personal tastes with facts, and represented them to you in a way as to hopefully garner a solution regarding adding a NAD 7600 into the stables. (With, oh course, the hopes oif someday running the mighty Cornwall III and letting my HIII's rest a bit.

[Z4!]

Of the three choices offered, I'd go for the 100wpc 2200. I'm sure others will advise to go with the 2600 and that is surely fine too; I'd just go more than the 50wpc if I had the option.

[Speedball]

Lot's of good information .......I was just going to say........it's a fine looking receiver.[]

[oldbuckster]

Don't fight it Get the Power, this is an old thread, and no one seemed to answer my question so, Crank the power on, the speakers will handle it..................Go for it Clarence...............

[colterphoto1]

Interesting, let me ask this; Aren't you better off using a higher powered amp/pre amp with the tone controls set at flat, as apposed to less power with the tone controls turned up?H2/3's and Cornwalls2/3's won't they kick-off if driven to clipping?It also seems to me that SS needs more power to sound the same as a lower powered tube set-up at the same volume setting?I don't know, just asking, seems to tie in with original question.

ok, I'll give it a shot.

I don't know why you'd have to adjust the tone controls for a different wattage amplifier unless something was seriously wrong with the lower powered one. Yes, using the tone controls, especially BASS, calls for reserves of energy, which the lower powered amp might not have, causing clipping.

I don't know anything about any 'kick-off' component in the CW or H systems unless the newer ones have them. The LS AL had diodes in the xover that were tweeter protection devices and maybe some of the other designs as well. Indusrials are fused in the back panel.

Many amps are not rated correctly. THere is what I call a 'balls' factor that seems to be in the power supply of SS amps. For instance, my little HK430 drives my Khorns just fine to nearly hideous levels. A modern Sony 20 wpc amp would sound anemic. It also goes back to that 'clean first watt' theory that for these super efficient speakers, many times we are in the very low wattage numbers, so the amp needs to behave with low THD and flat response as these lower outputs. Many do not. That might also be where the Tube advantage kicks in.

Michael

[oldbuckster]

Colter, let me put it this way, what is a better , using a higher powered unit with controls at flat, or using a lower power unit with controls turned up to compenstate for lack of proper tone control level, increased bass or treble response? Did that come out right, I hope. By kick off component, I mean Tweeter Protection, which if the amp clips, off go the speakers. Wouldn't that be more likely to happen with the lower power unit, with the tone controls turned up, as opposed to a bigger more powerful unit with tone controls at flat?

Too much power is less of a problem, than not having enough power, and turning up your tone controls to compenstate for bass or treble response....................

[Guest " "]

"will I be overdriving my HIII's with this reciever"

Yes it can happen.

The drivers individually can handle approx 100 watts for the woofer, 40 watts for the mid horn (per atlas specs) and 5 watts for the tweeter (per electro-voice spec's). The drivers can take higher peak signals for short bursts.

Now there is some power being soaked to ground by the crossover network, meaning the amp is putting out the juice, but some of it never makes it to the drivers.

So it doesn't take much to figure out that a 100 watt power rating needs qualification. Is this continuouis, program, at what frequency? If you play tricky math, you can come up with a spec sheet that will say the t-35 driver can handle 50 watts. But thats a peak measurement, and it certainly is not at 3000kz, the lowest recommended crossover point for the t-35.

Your amp has a rating of headroom or dynamic range. Depending on how your amp is scaled, this can add as much as 50% more peak power to the max output an amp can put out.

[marems]

Speakers do not like DC voltage, which is passed on from the amp or receiver when clipping is occuring. Its always good to have some sort of anti- clipping curcuitry built in the the amp or receiver.

[Duke Spinner]

apparently ..nobody reads Crown spec's ..

where they Usually rate THD at 1 watt as well as full power

[MrMcGoo]

The Duke is right, always look for the 1 watt distortion level. However, your ears should also be used as numbers can be used to lie. Klipsch speakers do not lie, they just put out what was put in.

Headroom is needed for good musical reproduction. The amount of headroom needed is a function of room size, listening habits, speaker sensitivity etc. More is better as long as the quality on the first watt is good.

Bill