Running Out of Power

[Q-Man]

Calling all you Tube Heads, and I mean that in a nice way. I thought that I would post this here in two channel land.

Now that my cabinets are finished for my modifeid Klipschorns I moved them into the theater room. The speakers just need a little more network tweaking and this project is over.

While trying to figure out how much attenuation the JBL tweeter requires I also began increasing the volume. I wanted to see how loud these speakers would play in this larger room. For the last year or more I've been doing all my experimenting in my smaller 16' x 20' room. I hit 110dB at my listening position

in this smaller room with the volume control around 11:00 O'clock on a 110 watt receiver. I think I could go a little louder, but my ears and the room can't take anymore. But, I do enjoy levels around 104 dB for short periods of time.

In the larger room I was using a six channel McIntosh

power amp rated at 200 watts per channel at 4 Ohms and 120 watts at 8 ohms. I wasn't watching the power amp, just the digital readout on the volume control. At -35 (what ever that means) I was taking readings of around 101 dB on the Rat Shack meter from my listening position. I increased the volume to -25 and and was only getting a reading of about 104 dB. I never went to below -35 before in this room, but I always had seven more channels playing. I never listen to two channel in this room like I was doing now. When I saw -25 I took a look at the power amp and the Power Guard lights were flashing. This means that McIntosh's Power Guards circuits were on. This is an anti- clipping circuit that reduces the volume or the power to the speakers to keep you from frying them. I slowley decreased the volume control untill the power guard circuit went off. I repeated this several times, and I can't go below -33 without going into clipping. I need to repeat this with a variety of CDs. My old standard was to not turn the volume control past 12:00 O'clock and you should keep the amp from clipping. How consistent are these new digital readout volume controls from one unit to another? Should I be warning everyone not to go below -33 or 35? Or is the McIntosh amp too protective?

Anyway, I now have midrange and tweeter drivers that can handle much more power the the stock Klipschorn drivers and I can't go any louder, because I'm running out of power with a 120 watt amp.

How do you Tube Heads use such low wattage? Also, if you enjoy high volume levels keep your room sizes below 7200 square feet.

For you theater people remember I was listening to two channel, something that I never do in this room.

So once I turn on my other seven channels I'm sure the sound level should improve without having to increase the power. But I'm maxed out, more would be better.

[Deang]

"How do you Tube Heads use such low wattage?"

Why that's easy Qman, I sit 3 feet in front of my speakers, and practically jam the drivers into my ears!

Well, I use 20 wpc with my RF-7's, and can hit semi-clean peaks of 105db. The room is 12 feet wide, and extends the length of the house (cape cod). The speakers are 9 feet apart, and I sit 9 feet back.

How big is this new room of yours, and how far back are you sitting now?

I remember when my buddy Mark moved into his new house, and after setting up his DQ-10's, I thought they sounded "small". The room is 22 x 26, and it wasn't long before he bought my RC-7's and stacked subwoofers.

Smaller rooms have their advantages.

I would say you need more power, but doesn't the K-horn only take 100 wpc to begin with? Of course, a two channel tube amp with 75 watts or so would play with much more authority.

[AnalOg]

semi-clean peaks of 105db

Dean,

What the hell is that, I must be missing something. Is that on slow or fast response on the SPL meter.

On slow thats some serious LOUD, on fast if there semi clean, I would say somethings WRONG.

Tom

[Q-Man]

Dean,

Part of the reason I posted here is because of your post about sensitivity, efficiency and room gain.

It's not a new room, it's just my same old theater room. I just havn't listened to music in there in a long time, and when I did before it was all multi- channel. I've been too busy in the smaller room that I mentioned. I've been working in there on this mod for over a year and any music listening was done in there to get familiar with the changing speakers.

The theater room is 17'x 50'x 8.5' The sweat spot is abour 25' in front of the speakers.

Your right about the power handing of the Klipschorn, but my weak link in my modified Klipschorns is now the woofer, not the tweeter and mid driver.

Sure it's the large room for me, but since I hit my limit it makes me wonder about these 3 watt set amps that are discussed. I didn't think my amp was clipping where I had it. I couldn't hear any distortion as a clue. That McIntoch power guard circuit must work quite nice. With other amps I would always hear distortion then back off the volume.

While watching movies the volume control never gets below -42. All those action scenes blow you out of your seat.

I think I'll add that my meter was set to "C" and Slow.

[minn_male42]

"semi-clean peaks of 105db

Dean,

What the hell is that, I must be missing something. Is that on slow or fast response on the SPL meter.

On slow thats some serious LOUD, on fast if there semi clean, I would say somethings WRONG.

Tom"

i thought the same thing when i read that......

[3dzapper]

Remember the FTC power rating rule allows amps under test to thermal cycle on and off while being tested and say nothing about clipping. So 100WPC is not availiable in a 100WPC amp in normal use. Plus they are rated at single frequencies from 20-20KHZ not all at once. The demand that music puts on amps is much more rigorous. If your average wattage use for a volume level calls for 2 watts an attack of a bass drum will be looking for about 64Watts and that bass player laying down the bottom, he wants some too as does the Tamborine Man.

There must be a reason Klipsch puts a 650 watt amp in an RSW-15.

Bottom line what you experienced is not unusual. You can just see it on your Marantz. The rest of us go blissly along in ignorance.

I think that tubes get away with it because rather than become harsh with odd order harmonics when they clip they compress the dynamics of the wave.

Rick

[minn_male42]

How do you Tube Heads use such low wattage? Also, if you enjoy high volume levels keep your room sizes below 7200 square feet.

the simple fact is that you cannot have low wattage with high volume levels in larger rooms....

basic physics do not allow that....

if you have a large room and require higher volume levels you will need more power... a simple fact.... whatever power you select...tubes..ss..digital... you will need more......

[Deang]

I rarely if ever use the slow setting. However, I did tonight, and really didn't see THAT big of a difference. I mean, when you flip to slow, it just stays in the area where fast was most of the time anyways. I won't agonize you with what I was listening too.

This thread is just going to end up being an extension of the "sensitivity/efficiency" thread.

In order for my RF-7's to deliver the flatest response possible, I have to have them on the four ohm taps. This means my RF-7's go from being an 8 ohm 102db/w speaker, to a 4 ohm 99db/w speaker. With 22 watts, I can hit peaks of 105db before I notice the pinching up I associate with clipping. When I flip to slow, it's a very steady, and very loud 100-102db. If you'll read through the other thread, you'll see that this right where I should be.

In defense of the low wattage folks, I will say that triode watts sound very "big", and I have found myself listening at lower volume levels since getting the Canary. There is something going on that belies the modest power rating. Hell if I can explain it. I suppose if I was forced to speak in audiophile language -- I suppose the best way to explain the sound is that it seems to permeate the air. Now, with that said, make no mistake -- the sound does not explode into the room like a good ultralinear amp, however, it sounds so good you don't care.

If I had Klipschorns in a big room like that, I would have them on a good 60 to 80 watt Ultralinear amp -- but I would definitely be building something up quick in a smaller room using low power -- with a nice chair 8 or so feet in front of the speakers.

[maxg]

Well for what its worth my immediate reaction is that it is the speakers and not the amps that is the limiting factor.

From memory the KHorn is 104 db/w/m sensitivity and will take 100 watts continuous. That equates to around 124 dB maximum at 1 meter from the speakers.

You sit 25 feet away which is roughly 8 meters. A loss of 20 dB over the extra 7 meters is fully believable.

If so then the highest peak value you should see is something in the order of 110 dB at your position (130 at 1 meter).

Big room!!!

[J M O N]

Q-Man:

That's gotta be the largest room on the forum!! FYI: I have Khorns in a much smaller room. I currently have a 40wpc ARC tube amp connected and they produce way more volume than I would ever want. True rock concert volume levels are easily achievable if so desired.

I have recently picked up a 2A3 amp to use. I have only briefly been able to audition them, but there was still plenty of volume. I didn't play them very loud, but there was more if I wanted it. Funny thing I kinda noticed is that I didn't feel like I needed to turn it up as loud. I haven't been able to spend enough time with them to really come to a conlusion yet, and I probably won't be able to for a while. Regardless, I would say though that I don't think anyone would recommend low power SET amps for home theater.

[Guest Anonymous]

I need to get me an spl meeter

[Allan Songer]

Just for the hell of it I pulled out the Radio Shack SPL meter and played some stuff that I ALWAYS play LOUD:

Miles Davis "On the Corner"

Miles Davis "Live at Fillmore East"

Lonnie Smith "Move Your Hand"

James Blood Ulmer "Tales of Captain Black"

Ornette Coleman "Dancing in Your Head"

My room is about 16 x 25 and I sit 12 feet from the speakers.

I could have chosen others, but these were at hand.

On the "slow" setting at what I consider CRANKED, the SPL meter NEVER got above about 101-103 db. How the hell can you guys listen to ANYTHING at volumes higher that than and still hear anything?

I then went beyond the threshold of both pain and good taste and turned it up to beyond half-way on the C22 volume control and the SPL meter was reading 107-108. Sounded like crap--even though it was still pretty "clean" and the bass wasn't fart-like yet, it was just TOO DAMN LOUD!!!

Am I getting old or what?

[Parrot]

Nobody is going to be listening that loud at average levels. It's the abliity or lack thereof to handle instantaneous peaks that is important.

I don't know how fast the Radio Shack SPL meter is. If it's not fast enough, then a lot of what everyone is discussing is not valid. All the manual says is that the FAST setting works "quickly."

[Deang]

I'm with you guys. It's nice to know what you can top out at -- but you sure don't want to live there. A clean 90-95db, and I'm very happy.

[Guy Landau]

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On 11/11/2003 8:05:29 PM DeanG wrote:

I'm with you guys. It's nice to know what you can top out at -- but you sure don't want to live there. A

clean

90-95db, and I'm very happy.

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So you're finally ready for SET .

[Q-Man]

I was just trying to make a point. Everyone believes that the mighty Klipschorn is so efficient that it doesn't need much power. That you could never feed it 100 watts and put your amp into clipping and be able to stand the volume.

The room really isn't as big as it sounds. When you think about it some of your rooms might have the same cubic footage. It's really 17' x 30' room, only seperated from the 17' x 20' kitchen by a 42" high knee wall that is 12' long and then a open walkway. Of cource the speakers see this area as a 17'by 50' room.

I've drawn up a dedicated home theater room that I'm hoping to build someday. Now I'm going to think about the design and size some more, because the Klipschorn won't be enought speaker to fill the room that I drew up. I now believe that 7200 cubic feet is about the largest room size that you should use the Klipschorn in. My modified Klipschorn midrange and tweeter drivers can handle four times the power that the stock Klipschorns can. By rights I should try to find a woofer that can handle 400 watts to replace the K33E. Then the speaker could handle 400 watts and I could use 400 watt amps. All this, and all I would do is increase the max. SPL levels by 6dB. Hardley seems worth it. But who knows? This hobby keeps leading me to places that I never thought that I would go.

On the other hand these modified Klipschorns sound so much better then the stock ones that I too feel that I don't have to turn them up as much as I used to, to hear what I want to hear from them. Maybe something that you Tube Heads are hearing from your amps. The only reason that I bought the McIntosh six channel amp is because of you Tube Heads. I was trying to get a SS multi-channel power amp that might resemble the tube sound. Did I achieve that? I don't know.

I will most some pictures of the finished modified Klipschorn in the near furture. I'm undergoing some more network tweaking. I have to go beyond a Klipsch designed network. I won't be using John Warrens beautifull sounding AA for this mod after all. I'll spare you the details for now.

[trvale]

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On 11/11/2003 8:00:04 PM paulparrot wrote:

Nobody is going to be listening that loud at average levels. It's the abliity or lack thereof to handle instantaneous peaks that is important.

I don't know how fast the Radio Shack SPL meter is. If it's not fast enough, then a lot of what everyone is discussing is not valid. All the manual says is that the FAST setting works "quickly."

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I don't understand instantaneous peaks. 106 dB is 106 dB whether it is for 1 sec or 30. I wouldn't want my system to ever have peaks that went that high. For me 95-100 dB starts to get really uncomfortable.

Q-man, if you are looking to replace the KHorn woofer with something that will produce higher spl's, look no further than Pioneer. They have a woofer that can handle 5000 watts! 170 dB!!! I would love to see a human being standing in a room filled 170 dB of sound.

Edit: By the way, I am running a 14 wpc Eico HF-81 and could never go back to 125wpc SS!