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post #181 of 958 Old 02-09-2010, 11:48 AM
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Quote:
Originally Posted by Sickneedhelp View Post


My main speakers have a Fane 18" with four inch voice coils. My upper subs are two 24" Fanes with 4 inch voice coils and 1/4 thick poly cones.

What is the DIY community using?

Pro sound oriented drivers typically require a heck of a lot less power. They are optimized for a different bandwidth than home theater marketed gear. Most average 'pro' drivers can't even begin to use 500 watts, despite being rated at a redonkulous number.

I have a few TC Sounds LMS 5400 18's, they have a 4" coil that is wound out of heavy gauge aluminum wire, dual 10" diameter spiders and it will move 38 mm one way in it's linear range. It will hard bottom at 44 mm one way, that's 88 mm p-p.

Moving mass is 575 grams... and it's motor develops a whopping BL^2 /Re of 176.44.

This is a picture of one beside a 'pedestrian' JBL 10" car sub.


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post #182 of 958 Old 02-09-2010, 11:55 AM
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Quote:
Originally Posted by Sickneedhelp;18101713 [B View Post

Ricci[/b], The upper and lower subs are being driven by a single Crest 9200 that at 20Hz does 2,350 watts per channel, both channels driven for a duration of seconds depending on when the breaker feels like tripping. If you zoom up to message 154 you will see what I was using for an amplifier until I decided it was to heavy to mess with for the difference in performance.

What is the DIY community using?.


I'm a little bit out of the "norm" I would imagine.

1 Mackie M1400i
2 Crown CE4000
4 Crest 8002 (the same amp that you mention below. I love this amp BTW)
2 QSC PL9.0 running on 240v
2 AeTechron 7560 monoblocks (92lb ea, DC coupled, MRI's, motors, subs, etc)

Quote:
Originally Posted by Sickneedhelp;18101713 [B View Post

Ricci[/b], basically you are correct. With rare exception (IPR is one) when I do the spec sheet, I bypass the breaker. This allows time for the measuring equipment to settle in and read what the unit does with hot transistors. Generally that allows the amp to run continuous sine wave until it overheats. To me, if the amp runs for several minutes at a given spec with the breaker bypassed, I'm comfortable with that rating and I know there won't be any issues in the field. Using a breaker that doesn't permit minutes of operation is a separate issue. Doing burst ratings is something that is marketing driven. So far, I haven't used burst ratings, yet companies like Lab Gruppen do. If the Crest 9200 above were rated burst exactly as Lab measures theirs, we could claim 4kW per channel and sell more amplifiers. What is saving us here is that most of our customers do compare amplifier sonic performance and feel that the 9200 has better low end punch than the Lab 6400, despite the ratings.

Crest owns the patent for PFC amplifiers. We had one called the 8002. It had great low end due to the stiff supply. The marketplace voted for the smaller and lighter non-PFC 8200, so we discontinued the 8002.

The IPR6000 versus 8200 is a dilemma since it will also nip at the heels of the 9200. It's a major concern since it cannibalizes one of our high profit margin models that we can still afford to build in the USA. Suffice it to say, the 6000 will turn the marketplace upside down, including ours. Pass the ammo please.

Manuf's like LG and Powersoft are using burst ratings quite obviously as mentioned.

Just to clarify you are saying that the IPR6000 should be nearly a replacement for a Crest 9200 and is a more powerful amplifier in everyday use than the 8200? (On paper it is.) Will you be discontinuing the Crest Pro series and more expensive Peavey's? What advantages does a 9200 have over a IPR6000?


IPR's are China manufactured?


Clarification #2. Crest nor Peavey currently have a PFC amplifier? Is this because of cost, complexity of design, weight, reliability, or some mixture of the aforementioned?

One more question and I do appreciate your answering our questions...If the IPR6000 does provide a true and reliable amount of power comparable to Crown IT6000's, Pro 9200's, QSC PL360's, etc...At a weight of 1/4-1/8th and a cost to the consumer of 1/2-1/8 of these other amps, with what looks like almost nothing inside the amplifier case, it must have some sort of new breakthrough in amplifier technology if not multiple ones, patents associated, etc, because it will be miles ahead of everything else on the market.

What are these new technologies or implementations that are allowing this revolutionary performance from the IPR line? How soon will we see this approach the entire Crest and Peavey lines and get licensed into plate amp technology for active subwoofers and speakers and car audio taking over the market there as well? I can only see this as being the eventual case if the amps perform as claimed.


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post #183 of 958 Old 02-09-2010, 12:05 PM
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Ah.. my bad... I was assuming you were asking what people were using for subs for home theater.

As far as power amps go, I am not quite the 'norm':


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post #184 of 958 Old 02-09-2010, 12:06 PM
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Nice "small room" set-up Mike.


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post #185 of 958 Old 02-09-2010, 02:00 PM
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Quote:
Originally Posted by michael hurd View Post

Most average 'pro' drivers can't even begin to use 500 watts, despite being rated at a redonkulous number.

Michael, I checked with one of our transducer engineers. He says our LoMax 18" in an eight cu ft box will handle 1200 watts sine wave @ 30Hz continuously. I've never known this engineer to BS anyone, so I'd bet on the above. B&C makes a 21" that is good for 2000 watts continuous

Ricci, Thanks for buying the 8002. Crest designed that one after I left, and before Peavey bought Crest. I have LOTs of respect for the QSC 9.0. Lack of PFC is a dollars per watt issue. The market decides. Ditto IPR6000 versus 8200 or 9200. Let the market decide. IPRs are made in China. Must say, their quality is very good. As for the technology, I have to stay zipped on that for obvious reasons.
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post #186 of 958 Old 02-09-2010, 02:06 PM
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Quote:
Originally Posted by michael hurd View Post

Ah.. my bad... I was assuming you were asking what people were using for subs for home theater.

Not sure if that was directed at me or not. If so, yes, I was asking about home theater. If not, ignore and don't read this reply.
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post #187 of 958 Old 02-09-2010, 02:11 PM
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A friend of mine loaned me a Peavey IPR1600 to run through the paces. So here is a mini review. I won't waste my time on the light weight or the ugly blue lights-except to say that I think it is a bad idea to have the power button and logo litwhen the unit is OFF. The lights glow brighter when it is actually on-along with the internal lights coming on.

My dummy load only goes down to 4 ohms-so I could not test 2 ohm performance. This was just a quick and dirty test-so I did not worry about betting exact numbers. I also did not do both channel driven. No regulated AC voltage-just whatever live voltage was available.

If you want to test it yourself- BE VERY CAREFUL!!!!! Ground is NOT the same on both channels. On one channel-pin 1 - is chassis ground. On the other channel pin1 + is chassis ground!

Be careful when hooking up scope leads and make sure how your dummy load does its grounding.

Anyway, the 8 ohm continuous sine wave output was just under 300 watts and the 4 ohm sine wave was right at 500 watts.

So now the heating test, I ran music into hard clip (the DDT light was on more than it was off) into a 4 ohm load for 4 hours. The amp was just sitting on the bench. Not only did it not get hot-I could not find any place on the chassis that I would even call warm. Because of the fan cooling-I am not sure it even got up to room temp.

I backed the power down to just under clipping, and the chassis was actually cold on the exhaust exit (where it should be hot). This thing is VERY efficient.

Freq response. When sweeping down in freq it is rock solid until 8 hz. At 7 hz the level dropped quite a bit and started fluttering. However I had to raise the generator to 11Hz to get it stabile. Again, this is sine wave and was tested at around 300 watt output.

The generator I was using only goes to 20Khz and it was flat up to that freq.

I have not listened to it (that is for another day), but so far on the bench I am pretty impressed.

No, I did not do distortion tests. This was just a quicky thing-in between everything else I have to do.

So far I am impressed. I wonder how good the DSP version is.

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post #188 of 958 Old 02-09-2010, 02:27 PM
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Hi Ivan,
I know you are busy, but if you have the opportunity could you please bridge it and see if it holds up? I asked JD earlier and he said
Quote:
The 1600 & 3000 can be externally bridged. Inputs get paralleled (no polarity flip). Output connects to CHA 1+ & CHB 1- This works because B channel is inverted in the signal path and inverted back at the spkr connector (two wrongs make a right). Crest versions get a bridge switch and dedicated bridge output connector.


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post #189 of 958 Old 02-09-2010, 02:31 PM
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"He says our LoMax 18" in an eight cu ft box will handle 1200 watts sine wave @ 30Hz continuously. I've never known this engineer to BS anyone, so I'd bet on the above. B&C makes a 21" that is good for 2000 watts continuous"

Are those "real" rms watts?

Whenever I read the pro audio spec for power, I never quite get what it means; IIRC it's pink noise w/a crest factor, and it's not clear what the equivalent heating effect is.

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post #190 of 958 Old 02-09-2010, 03:26 PM
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[quote=noah katz;18103302 Are those "real" rms watts?[/QUOTE]

Yes, continuous sine wave, A.K.A. real watts.
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post #191 of 958 Old 02-09-2010, 04:11 PM
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Watts can be misleading. Voltage into the load would be more appropriate.

For instance, at 30 hz, depending on the enclosure and driver combination, you could see anywhere from 3 ohms to 50 ohms.

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post #192 of 958 Old 02-09-2010, 04:57 PM
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Looking at the specs on the Lo Max 18 @ the Peavey website, in an 8 cu ft cab tuned to 33 hz, the driver is moving it's full rated excursion @ 1200w. ( 10.2 mm ) It should be able to cool itself with that much excursion.

@ 48 hz, 1200 w PIN puts it already 3 mm over it's coil overhang.

550 watts is much more realistic power handling across the board. Adding an even modest 100F coil temp increase, I'd de-rate it even more, closer to 400 w.

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post #193 of 958 Old 02-09-2010, 05:18 PM
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From the above, you might think that I dislike Peavey... but that isn't the case, infact I do like the Peavey Low Rider 18.

I helped a friend out who wanted a pair of cabinets to fill in the bottom end of a pair of Heresy Industrials for in shop as well as outside use.

http://forums.klipsch.com/forums/t/129471.aspx

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post #194 of 958 Old 02-09-2010, 08:03 PM
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Keep in mind that as the voice coil heats up, its impedance rises so more voltage out of the amp looks like less power...also, the Xmax is usually 70% of Bl, so there's usually at least another 30% of very nonlinear throw. As the Bl goes down, the excursion is no longer a linear function of input power. In other words, you've got a few variables changing the electrical voltage to excursion ratio (gain if you will) that will make it seem like the driver can handle more power than the linear models predict. It behaves much like a compressor which is why I think the name "power compression" is so fitting.

I believe 100W of pink noise with 20dB crest should be 100W "RMS" with occasional peaks showing up 20dB louder. You really can't have "RMS" power, but it's referring to the RMS voltage being used to calculate the average power. Crest factor is the ratio between the peaks and the average. Wikipedia has a cool table of RMS vs average values for different waveform shapes:
http://en.wikipedia.org/wiki/Crest_factor

However, 100W with 20dB crest seems kind of insane because that would be a 800Vp-p signal into an 8 ohm load. That's got me wondering if maybe the average power isn't 20dB lower than the 100W, but that would be misleading because the real average power would then be 1W....either way, there's a 20dB difference between the peaks and average. Also note I didn't say 10,000W peak because you can't really have peak power either.

In fact, the power being pushed out by the amplifier doesn't all go into the speaker either. I would love to see some power factor measurements of speakers, but I do know that a perfect inductor has a power factor of 0 (which means a perfect inductor dissipates no power). Speaker motors are predominantly inductive, but there is some resistance and capacitance too. At the very least, I believe the Re of the coil should determine the minimum amount of heating you'll see.

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post #195 of 958 Old 02-09-2010, 08:54 PM
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All of which gets so complicated that you can't answer the customer when he asks how many watts worth of amplifier he needs to drive his Big Woof brand piezo tweeter array. So..... we conclude a nominal impedance, determine the max voltage, and pretend it's watts. That way us amp guys can consume a career extrolling the virtues of how our amplifier drives a resistor better than the other guy's.
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post #196 of 958 Old 02-09-2010, 09:08 PM
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lol, truer words were never spoken.

For what it's worth, my comments about power factor are more aimed towards speaker design than they are amplifier design...the amplifier would need to work just as hard regardless of the power factor.

At the end of the day, I don't think there will ever be a single marketing spec that could be used to rate amplifier performance perfectly. It's a multi-dimensional problem trying to be described with one variable...there will always be some assumptions made that aren't applicable to very application.

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post #197 of 958 Old 02-09-2010, 09:43 PM
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JD, thanks for the clarification on power spec's.

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post #198 of 958 Old 02-10-2010, 08:55 AM
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Quote:
Originally Posted by Ivan Beaver View Post

So now the heating test, I ran music into hard clip (the DDT light was on more than it was off) into a 4 ohm load for 4 hours. The amp was just sitting on the bench. Not only did it not get hot-I could not find any place on the chassis that I would even call warm. Because of the fan cooling-I am not sure it even got up to room temp.

I backed the power down to just under clipping, and the chassis was actually cold on the exhaust exit (where it should be hot). This thing is VERY efficient.

Thanks for the mini review - that's some good news. I doubt I'll be replacing my QSC sub amp for one of these, but if they stay that cool they should hold up pretty well.


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post #199 of 958 Old 02-10-2010, 11:12 AM
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Interesting report Ivan...I was about to copy it to here form PSW. No need now.


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post #200 of 958 Old 02-10-2010, 07:23 PM
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Thanks Ivan.

This might be perfect for me. Anyone know how loud the fans are on these? It won't be in a closet for a while... my ep2500 would drive me nuts if I had it in my room.
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post #201 of 958 Old 02-10-2010, 08:52 PM
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The fans on Peavey amps (Crest as well ?) are variable speed controlled so near silent...

Cheers..
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post #202 of 958 Old 02-10-2010, 09:27 PM
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Monger, if you use it at four ohms it will run relaxed and relatively quiet. I tossed one on the test bench today to qualify "continuous power". To prevent the circuit breaker from tripping, I ran it one channel at a time. Each channel did 600 watts <0.1% for ten minutes before I stopped the test. Since there are no heat sinks, equilibrium takes a minute or so. Ten minutes is basically the same as years. Running typical program material at four ohms simply doesn't require much cooling. If it is too noisy, trade it in later for the Crest version. It gets extra enhancements, but will cost you more.

At two ohms things change. The fan will wail and you are thermally limited to a 22% duty cycle if pushed to full power. That covers normal program with some margin.
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post #203 of 958 Old 02-11-2010, 03:47 AM
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Quote:
Originally Posted by Ivan Beaver View Post

Anyway, the 8 ohm continuous sine wave output was just under 300 watts and the 4 ohm sine wave was right at 500 watts.

So now the heating test, I ran music into hard clip (the DDT light was on more than it was off) into a 4 ohm load for 4 hours. The amp was just sitting on the bench. Not only did it not get hot-I could not find any place on the chassis that I would even call warm. Because of the fan cooling-I am not sure it even got up to room temp.

I backed the power down to just under clipping, and the chassis was actually cold on the exhaust exit (where it should be hot). This thing is VERY efficient.

Why baby the amplifier? if you did a continuous sine wave test to
calculate "watts" (assuming this was a short duration test), why
switch to a music test and claim it's a "heating test" ? Playing music
vs. sine waves is cake walk for any amplifier, a real heating test is
to let the amplifier run those sine waves at lowest rated impedance
to get a smile or a kaboom.




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post #204 of 958 Old 02-11-2010, 03:49 AM
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Quote:
Originally Posted by Sickneedhelp View Post

Monger, I ran it one channel at a time. Each channel did 600 watts <0.1% for ten minutes before I stopped the test.

Gotta love the one channel only testing. Imagine if automobile manufactuers use this method to test their engines.
Chuck was doing one channel only tests on certain amplifiers, IIRC the PLX (I have those). Since I run them in bridge
mode, it's silly to have one channel tested as you use two by default in this mode - I want to know the real skinny... :wink:



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post #205 of 958 Old 02-11-2010, 05:07 AM
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Quote:
Originally Posted by thylantyr View Post

Why baby the amplifier? if you did a continuous sine wave test to
calculate "watts" (assuming this was a short duration test), why
switch to a music test and claim it's a "heating test" ? Playing music
vs. sine waves is cake walk for any amplifier, a real heating test is
to let the amplifier run those sine waves at lowest rated impedance
to get a smile or a kaboom.


I was runnng sine waves for several minutes before I took my "readings". Now they could be off a little bit, as where I had the amp setup and my good HP voltmeter were not in the same place-so I was just using my handy VOM.

So it would not be considered short term.

If you say that running an amp into hard clip is a "cake walk", then consider this. I have tested thousands of amps over my career (most of the time as s bench tech), and when run this way they would ALL get pretty hot-even single channel driven.

Maybe you have tested some that don't-but I haven't. Now granted I have not tested every amplifier-but enough to be able to make a real statement based on actual testing-not "arm chair quarterback" type guessing.

But this amp didn't even get the slightest bit warm. I am talking about getting up to room temp-and that is after 4 hours-non stop. When run just below clipping-the amp was actually COLD to the touch.

This temp comparison was using the "high tech" way of touching the amp chassis and other pieces of metal around the same area.

I have NEVER seen any amp that ran this cool.

I disagree about using sine waves to even attempt to test an amp for heating in a real world situation. Great for various other testing-but that would overheat just about any amp. So what would that prove. I believe in some type of tests to find the limits-and other types of tests that attempt to simulate the real world.


Yes I only drove a single channel-but do you really think that driving both channels would result in a huge increase in heating? Some yes-but nowhere near enough to keep me from saying this is a VERY COOL running amp.

Please enlighten me on other amps that run this cool.

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post #206 of 958 Old 02-11-2010, 06:25 AM
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Quote:
Originally Posted by Ivan Beaver View Post

If you say that running an amp into hard clip is a "cake walk", then consider this. I have tested thousands of amps over my career (most of the time as s bench tech), and when run this way they would ALL get pretty hot-even single channel driven.

No one said it's easy on the amps. But fact is that it happens all the time in pro audio, heck, i've seen DJs overdriving $3k+ Pioneer consoles all night long, and not only once.

Quote:
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Yes I only drove a single channel-but do you really think that driving both channels would result in a huge increase in heating? Some yes-but nowhere near enough to keep me from saying this is a VERY COOL running amp.

Well, both channels driven = double the power thus double the heat. I agree with the results of your tests though, with one little gripe - you said it runs cooler than room temp. The laws of physics say that's impossible, since you're still using air in the room to cool the thing.

Thing is, by the looks of its internal structure, and by the Peavey guy's comments, heat isn't coupled to its case at all. Have you tried touching the output transistors? I've had my experiences with fans exhausting cold air while devices were melting inside. I sure hope it's not the case here though.

Anyway, if it becomes available in Romania at a reasonable price (i know it's gonna be more than $300 here but let's see how much), i'll buy one this summer since i need a pro amp of this power. And it's going to be used entirely for pro audio jobs, mostly for driving subwoofers as the top end is covered already.

Quote:
Originally Posted by Ivan Beaver
The nice thing about standards is that there are so many to choose from.
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post #207 of 958 Old 02-11-2010, 07:15 AM
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Originally Posted by thylantyr View Post

Gotta love the one channel only testing. Imagine if automobile manufactuers use this method to test their engines.
Chuck was doing one channel only tests on certain amplifiers, IIRC the PLX (I have those). Since I run them in bridge
mode, it's silly to have one channel tested as you use two by default in this mode - I want to know the real skinny... :wink:

Thylantyr, I noted reading some of the Pro Sound forums that this topic comes up occasionally. Someone claims amps need to do 100% duty cycle and 50 people jump in and bitch slap him back down. Now .... in this forum we are way too polite to do that. I'll just calmly (while biting down hard on a stick) tell you that you must get a grip on the real world and let go of some of your assumptions. The audio field is a small market. Us old timers didn't survive this industry because we don't know what we are doing. We don't get paid for making unsuccessful product that doesn't work for the customer. Some of us have too much street cred and too many recognitions and product awards through the years to not have learned a few things about reality. We know how to make sound for tens and hundreds of thousands of people. We also know how to make enough sound to fill up a living room.

My published spec sheets give single channel and dual channel continuous power ratings. They also give 20Hz to 20kHz ratings. You can go on line to get them. The breaker limitation that caused me to do single channel measurements and post them at 202, is not a way to make something that doesn't work and then trick the industry into thinking that they can actually use the non-functional amplifier so that we can take the money and run. Sorry for the long sentence and poor grammar. Imagine what would happen if there were a rap concert with a full house and the sound system failed because the amplifiers shut off. How long do you think our doors would be open if our dealers kept getting returns from their customers because amps shut down?

Buy an IPR, use it, flog it, then comment if it doesn't perform for you. I'm sure the dealer will refund your $299 if it doesn't meet your expectations. Until then, you are only speculating and spreading bad vibes, (unlike the boquet of roses I'm spreading here).

The PLX you said you run in bridge mode is a fine amplifier. Kudos to QSC. Bet they would tell you it will not run full power on both channels for more than a fraction of a second. Bet they also don't care that it doesn't. They sell LOTS of them.

Okay, morning rant is over, stick is being removed.

As for Ivan's metaphor "runs cooler than room temp", I'm sure that's just a global warming caused anomaly that is responsible for everything that isn't George Bush's fault.
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post #208 of 958 Old 02-11-2010, 08:31 AM
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Originally Posted by Sickneedhelp View Post

Buy an IPR, use it, flog it, then comment if it doesn't perform for you. I'm sure the dealer will refund your $299 if it doesn't meet your expectations. Until then, you are only speculating and spreading bad vibes, (unlike the boquet of roses I'm spreading here).

Subjective reviews dont hold much water here. I'm with Thylanter and I'd like to hear some quantitative numbers. What will it do continuous into a 4 and 8 ohm load bridged? Any other measurement (subjective or objective) is of little use to me.

It may not matter to most pro audio people but it matters to us.

Quote:
Originally Posted by vasyachkin
Even i, the genius, only vaguely understand what i am saying here.
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post #209 of 958 Old 02-11-2010, 09:03 AM
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Hey JD,

Do you have any word about the IPR6000? When it will be available, pricing, weight, the owners manual and detailed specifications? Anything? That's the one that a lot of people are interested in and I may have to buy one and give it the real world subwoofer/ amplifier test ( quite a bit more strenuous than some concert kick drum) . If it works out I may be able to sell all of my old amps convert to the 6000's and make a small profit in the process.

I'm still skeptical, but hey that would be some tasty Kool-aid.


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post #210 of 958 Old 02-11-2010, 09:20 AM
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Originally Posted by LHD21 View Post

Subjective reviews dont hold much water here. I'm with Thylanter and I'd like to hear some quantitative numbers. What will it do continuous into a 4 and 8 ohm load bridged? Any other measurement (subjective or objective) is of little use to me.

It may not matter to most pro audio people but it matters to us.

Okay, I'll play along. What currently mass produced amplifier are "us" using that has a fuse or circuit breaker allowing continuous sine wave full power?

Ricci, the 6000 will be a few months still. Electronic component deliveries are as much as six months on ceramic capacitors and semiconductors. Nothing is happening on schedule these days.
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