Sierra Ribbon Towers and Safe SPL

[curtis]

Uh yeah, I’m pretty sure it was Mike....

[davef]

Uh yeah, I’m pretty sure it was Mike....

You remember that incident? Was I right that it was about a decade ago?

[mikesiskav]

I don't remember that lol.

[curtis]

You remember that incident? Was I right that it was about a decade ago?

It might be longer...
I only say it was Mike, because I don’t have any Linkin Park as part of my demo/test tracks.

[davef]

I deduct 3 dB sensitivity for the 4 ohm Sierra towers.

http://myhometheater.homestead.com/splcalculator.html

The speaker impedance specification doesn't matter in these calculations since our sensitivity specification is properly based on voltage, not power. This is the correct way to list sensitivity because impedance varies considerably with frequency. To properly determine what sensitivity to use in this calculator, someone would have to estimate the average impedance value within the typical sensitivity frequency range (typically from 300Hz to 3kHz)

[davef]

I don't remember that lol.

At that time, it was the latest Linkin Park release, you (or it was someone else) was impressed with how deep the bass went. It was very problematic for the Song Tower, but it also badly "popped" the woofers in our tower as well. I didn't own that Linkin Park CD so someone brought it here -- don't think it was Mitch but maybe.

[Pogre]

Thank you Dave.

Yes that makes sense. To be honest I have never measured spl at MLP at that volume. I do have REW and a UMIK mic tho, so when I rearrange and recalibrate my subs I'll try raising the volume in increments and see where levels are in relation to the number setting on my dial using REW's built in tone generator and spl meter.

I agree with you that 97 dB is dangerous and I want to know if that's where I'm at. I'll be shocked if I'm at, or over 100 dB at my seat with music. I've been assuming 85 -90 dB at the "0" setting on my dial, which is what I've been referring to as reference. Sounds like I might be surprised... I'm not trying, nor do I want to hit 105 dB. I never watch movies over -10 or -15 at the most. Above that is just too loud to the point unpleasant.

I like to turn up music sometimes tho. I played drums for years and one of the examples I posted above is a drum solo. That recording sounds so good and he's such a talented drummer I just can't help myself. I turn it up almost every time it plays and it almost sounds like his kit is in my room. When I close my eyes it feels like I'm transported there. I'm used to practicing on the drums so, well, a 2 or 3 minute solo played at max volume every once in a while is right up my alley.

I have definitely not heard those drivers bottom out and appreciate you confirming that they appear to be operating within limits, provided my amp isn't clipping. I can't say I've heard any bad behavior at all, and I've tried to listen for it. FWIW my amp really seems to love the Sierras. It has not gotten more than lukewarm since I've had them hooked up, no matter what I've thrown at it. I know that doesn't mean there isn't any clipping at high volumes, but it is something I noticed that I appreciate.

[davef]

And is the visible excursion within design spec of the driver(s)?

Absolutely, this is how woofers produce sound - they "woof"

[Pogre]

Yep - we use a shallow slope on the mid crossed to the woofers, and a steep slope on the woofers crossed to this mid. Plus that SVS Ultra tower has (2) mids, that automatically cuts the excursion requirements in half, plus they are larger woofers which increases efficiency - further reducing excursion requirements at the same volume levels.

Pogre, you really can't compare one speaker to another with regard to excursion, unless it is a subwoofer with the same size woofer and similar tuning, similar filtering and EQ. It gets complicated. Our Towers were not designed as SPL beasts but I have run ours in our demo room at 110dB for hours at a time, at a listening distance of about - 9 feet in a very well damped room. We have had customers turn up the volume to insane levels at times, often prompting me in the factory area to knock on the door and ask them to turn it down a bit. We have had these same towers in our demo room, which have been seriously abused and with many thousands of hours of listening time on them for close to ten years now. We have yet to have to swap out a woofer or the RAAL 70-20xr. In fact, I believe in an early demo of the towers - I believe Curtis and some other people accidentally bottomed the hell out of the woofers when Mike (I believe it might have been Mike but I could be wrong) played an insane Linkin Park track, full range at about 110dB.

Even more reassuring to you - in many thousands of ribbon towers sold, we have only had (2) customers damage the RAAL 70-20xram. One because the tower got knocked over and landed square on the face, basically shattering the tweeter - and another who used the towers outdoors at his own party, threw an insane amount of power into them and burned up every component, including melting the inductors and resistors in the crossover. That was an interesting situation, as the customer attempted to blame the speaker and fought with us over the warranty -- that was until his some dropped the speaker off at our facility, met Dina and Joe - felt bad and told us the truth as to what really happened

Oh I know it's apples and oranges. I only mention it because it's what I'm used to seeing. Of course I expect more excursion from smaller and fewer drivers. How much more is what I was unsure of.

[davef]

Thank you Dave.

Yes that makes sense. To be honest I have never measured spl at MLP at that volume. I do have REW and a UMIK mic tho, so when I rearrange and recalibrate my subs I'll try raising the volume in increments and see where levels are in relation to the number setting on my dial using REW's built in tone generator and spl meter.

I agree with you that 97 dB is dangerous and I want to know if that's where I'm at. I'll be shocked if I'm at, or over 100 dB at my seat with music. I've been assuming 85 -90 dB at the "0" setting on my dial, which is what I've been referring to as reference. Sounds like I might be surprised... I'm not trying, nor do I want to hit 105 dB. I never watch movies over -10 or -15 at the most. Above that is just too loud to the point unpleasant.

I like to turn up music sometimes tho. I played drums for years and one of the examples I posted above is a drum solo. That recording sounds so good and he's such a talented drummer I just can't help myself. I turn it up almost every time it plays and it almost sounds like his kit is in my room. When I close my eyes it feels like I'm transported there. I'm used to practicing on the drums so, well, a 2 or 3 minute solo played at max volume every once in a while is right up my alley.

I have definitely not heard those drivers bottom out and appreciate you confirming that they appear to be operating within limits, provided my amp isn't clipping. I can't say I've heard any bad behavior at all, and I've tried to listen for it. FWIW my amp really seems to love the Sierras. It has not gotten more than lukewarm since I've had them hooked up, no matter what I've thrown at it. I know that doesn't mean there isn't any clipping at high volumes, but it is something I noticed that I appreciate.

You are very welcome and I am thrilled you are enjoying the towers. Curtis turned me on to an incredible Sheffield Labs drum solo CD that I often use for demos. It is one of my favorites and I like it loud.

To be honest I have never measured spl at MLP at that volume.

I'd recommend it. Those ribbon towers are so clean that we often don't realize we are listening at very loud volume levels.

I've been assuming 85 -90 dB at the "0" setting on my dial, which is what I've been referring to as reference.

This is the wrong assumption to make and I'll explain why. Ever notice that one CD will sound so much louder than another? There are literally no standards with regards to 2-channel mastering levels. That "0" volume level setting assumes a specific input voltage and that is fixed for the Dolby Digital spec. Pre-amps and Amp's just take the source signal and amplify it - they are not self monitoring devices, they don't measure output voltages to maintain 85dB at any input voltage level.

If you have a CD that is recorded hot, and unfortunately - so many of them are these days, - if that CD is +6dB (many are even higher so they sound louder) - than that "0" setting is actually 6dB higher. For example, if the 0 db setting calibrates to 85dB at your listening position for Dolby Digital, that hot CD could very well measure an average of 91dB.

Since you are really into this, I strongly recommend picking up a decent SPL meter from Amazon. It is a very useful tool and they don't cost much.