Will this set up produce good spl?

[organ]

Will the RF-15 put out some serious spl with the nOrh SE9 integrated tube amp in a small room? The int is rated at 9w/ch.

www.nohr.com/products/se9/index.html

Thanks

Maurice

[lynnm]

A 9 watt/ch amp will yield an SPL of 106db +/- at 1 metre ( approximately 39" ) from each speaker resulting in a combined 107-108 db Spl at that distance. Translation = LOUD

That little Norh might be a little hard put to play really loud in a large room but the combination of 9 watts/channel and 96 db/w/metre looks like a winner for a small room.

The other consideration is that even those with powerful amplifiers rarely draw more than a few watts under normal listening conditions. Braggin' rights aside most ( even those of y'all with 3 sets of organs Like fini) listen to music at the 60-70db. level most of the time. You would be getting there within that first watt.

[Audio Flynn]

SPL ios not a primary objective!

[Tubinhard]

Maurice's primary objective obviously isn't 'loudness'. I mean, looking at a 9 watt amp makes that kind of obvious.

"A 9 watt/ch amp will yield an SPL of 106db +/- at 1 metre ( approximately 39" ) from each speaker resulting in a combined 107-108 db Spl at that distance. Translation = LOUD"

I wish folks would quit figuring it this way, because it doesn't work. 5 minutes with some watt meters, and an SPL meter -- shows just how far off figuring SPL as above is. If you have 9 watts, and use all 9 watts -- you'll be in clipping 75% of the time. Also, if those speakers are not positioned in corners, sensitivity will drop to 92db/w.

I can safely predict that with that amp, in an average size room, with those speakers, a steady 85db, with near 90db peaks will be reached -- cleanly. This is probably plenty loud enough for most people, but not all. Personally, I consider 60db to be a near whisper.

[jt1stcav]

I'm lousy at math...how does that translate with an 8 watt amp driving horns with 98.5dB @ 1W/1M? Maybe about 107 or 108dB at 1 meter? According to Dean, most likely much less. My Cornwalls are in the corners slightly toed in.

[Audio Flynn]

Dean,

The deal is what music software preferences and other considerations are important.

Some people use a Nohr; some sold it.

It may not have the "meat", detail, and fullness one would quest for, from other comments I have read in the past year.

As you have said...

SPL is influenced by many factors.

-distance from speakers

-room size and orientation

-placement in realtion ot reart wall and corner

Nothing I have read indicates a Nohr is a long term investment.

NOTE

Room sizes in Europe are small.

Large houses are for the aristocracy.

Nohr is a european desin as I recall.

[Johnny dB]

Tommorow morning, I will hook up my 8W/ch tube amp to my Khorns, bust out the Digital sound meter, and voila, I'll post my test results. I love science projects.

[Klipschfoot]

----------------

SPL ios not a primary objective!

----------------

I remember an album, maybe James Gang - Rides Again?, that had "made loud to be played loud" inscribed either in the inner blank groove or, perhaps, it was on the album spine. So, there CAN be an invitation to crank it from the artist. Just ask The Nuge!

[Johnny dB]

Test results are in!

First the setup:

S-5 8 watts/ch tube amp uses 4 x 11ms8.

Dynaco CDV-1 CDP

2 x Klipschorns

Tape measure

Radio Shack Digital Sound Level Meter

After letting the amp warm up for over an hour, popped in Norah Jones CD. With the volume at 12:00 on the CDP and 11:00 on the amp. 98dB w/ peaks at 102dB @ 39" approx 1 meter. Then I popped in the Toadies CD. 100dB w/ peaks reaching 106dB. Sound was still nice and clean. If the volume went any higher than that, sound quality degraded drastically.

[NOSValves]

John,

Why at 39" what about in the spot you listen at ?

Craig

[Johnny dB]

That was reference the point they used in earlier post.

[Johnny dB]

From my listening position (11'6") from both speakers. 99dB w/ peaks @ 101dB. That's w/ Tool in the CDP.

[Colin]

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On 12/30/2003 10:31:52 PM organ wrote:

Will the RF-15 put out some serious spl with the nOrh SE9 integrated tube amp in a small room? The int is rated at 9w/ch.

www.nohr.com/products/se9/index.html

Thanks

Maurice

----------------

Yes, the nOrh SE9 will put out loud SPL, but that is not the issue, any noisy receiver will put out crap that sounds loud, compared to other tube amplifiers, like the ASL, I think you will be disappointed by the SE9 sound with big ole horns, I know that I was

[Tubinhard]

That's about right John.

Now, let's figure it using just math that most use.

The Klipschorn is 104db/w, add 3db for the other speaker, and we are sitting at 107db/w.

1 watt = 107db

2 watts = 110db

4 watts = 113db

8 watts = 117db

You are about 12' back, and so now we subtract 3db for every 3 feet you move away from the speakers.

117db at 3 feet

114db at 6 feet

111db at 9 feet

108db at 12 feet

So now, someone would say that with 8 watts and Klipschorns, you should be able to hit 108db, 12 feet away -- but that's not what you found is it? In fact, you found EXACTLY what we have been saying since last month: That you need between 3 and 5 times the steady state amount (depending on recording), to reproduce the peaks cleanly. Your ears were telling you that 99db was pretty much IT. Where did the rest of the ouput go? This is the difference between "watts", and "acoustic watts".

Now, and I know this is hard for people to accept, but because of the soft clipping nature of tubes, and especially SET amps -- dynamic peak restriction is clearly evident when you compare lower power to higher power. For example: with a 30 watt amp, your steady 99db would have been generating peaks of near 104db. Try your experiment again with another amp. Take it up to 99db and watch the peaks.

[Johnny dB]

Learning is fun!

I'll have to do the SPL thing with the MC250, tomorrow. I have to go earn a living now. Can't just sit on my couch all day and play with my meter.

[sfogg]

Dean,

" and so now we subtract 3db for every 3 feet you move away from the speakers. "

Where do you get that number from?

The normal fall off of a point source speaker is -6dB every time you double the distance. It is the inverse square law.

For a line source it is about -3dB every time you double the distance.

I believe a horn is closer to a line source then a point source in power drop off since its output is more focused.

JOOC, I was playing around with this a little last night.

Playing a pink noise source (equal energy per band which is a little more brutal then *most* music) to hit 85dB at my listening position (C weighted which reduces the SPL level a little because of the lower weighting in the bass) from one speaker playing was about 0.93v on my RMS multi-meter. I didn't get a chance to crack out my bench meter or my unweighted RTA. Making the assumption that the speaker was presenting about a 6ohm load I was putting about 0.1w into it.

That test tone was recorded at -20dB on the CD. Without changing my systems volume I can then determine that to reach the highest peak I would need 10w of power.

85dB at 0.1w (record level -20dB)

95dB at 1w (record level -10dB)

105dB at 10w (record level 0dBFS)

For those also into HT you might recognize that 105dB peak per speaker at the listening position is THX Reference Level for main channel speakers.

Shawn

[sfogg]

I just checked my notes and need to make a correction to the above numbers... when I tested in my normal setup of the speakers high passed at 60hz I was measuring .81v for 85dB at the listening position. That equated to the 0.1w I posted above.

When I was running the speakers full range I was measuring 0.93v which is:

0.14w of power at 85dB (record level -20dB)

So I'd need

1.4w of power for 95dB (record level -10dB)

14w of power for 105dB (record level 0dBFS)

Shawn

[lynnm]

I submit that the original question was whether the n0rh amp could drive those speakers to serious SPL's and my answer was and is yes. Furthermore the original post specified that the room is a small one. All the more reason to state that the system could indeed reach high volume levels.

I cannot comment on the sound of that amp as I have never heard one but I have no reason to suspect that it should not be a decent little amplifier and well suited to high efficiency speakers. I second the recommendtion regarding Antiqe Sound Lab amps having been well pleased with my AQ1003DT.

Dean I think you need to rethink your ideas about the need for large amps with Khorns. My AQ1003DT is rated as being able to deliver 30 watts per channel and believe me when that baby is cranking my horns the walls are vibrating and the windows and window blinds sometimes rattle......Soooooooo do I need 2 or 3 times that power to get the best from my horns ?

I don't think so unless I were trying to deafen the next door neighbours

[Tubinhard]

Oh Lynn, I agree with you completely. I think 30 watts is plenty with Klipschorns, in fact it was perfect amount with the RF-7s. 30 watts is a number I'm very comfortable with. It's 10 watts and under that I'm a little leary of -- but only because of peak demands at the higher levels.

My next venture, though power being way beyond what is necessary or even reasonable -- is more centered around my curiosity regarding the sound of the circuit. I just want to hear a good hybrid approach, and see what the Klipschorns do with an amp not influenced by variations in load impedance.

[organ]

Thanks a lot for the help guys. Someone I know on the Polk forum is thinking about that amp to go with a pair of RF-15. He took a look at ASL as well and I see that some of you recommend the ASL over nOhr.

Thanks for the help.

Maurice