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Thread: Sierra Ribbon Towers and Safe SPL

  1. #1
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    Default Sierra Ribbon Towers and Safe SPL

    Hey guys, I've had my new towers for about a week now and am really enjoying them. Gorgeous sound.

    I'm also using a pair of subs and cross them over at 80 hz, which is working really well. My normal listening volumes are 75 dB for music and usually less for movies and tv. However, I do like to crank up the volume from time to time and push reference levels for a song or 2.

    So I did that with Chocolate Chip Trip, a drum solo with an aggressive kick that comes in around 2 minutes.



    I sit 15' from my speakers and that song (among others with good bass) really seems to push the Sierra towers right up to the hairy edge of blowing a bass woofer (midrange also). I can see them moving, easily from where I sit 15' away. They move A LOT. The word "alarming" comes to mind... lol. I don't think I heard any clipping or distorting tho. I have a Monolith 7 amplifier and it's rated conservatively at 350 WPC into 4 ohms.

    Am I becoming alarmed for no reason? Anyone else feel like they've hit limits with the towers? Dave, what say you? Should I use a higher crossover when turning it up like that?
    Last edited by Pogre; 06-11-2020 at 08:00 AM.

  2. #2
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    Default Re: Sierra Ribbon Towers and Safe SPL

    Well geez guys, don't overwhelm me with replies!

    Okay, so I've made it to page 6 of the tower discussion thread and a couple things Dave said seem promising and I've been a little bit braver the last couple of days.
    Quote Originally Posted by davef View Post
    Loudspeaker power handling = massive! (we have yet to reach the speaker's limits but I would estimate it to be about 350 clean watts)
    My amp tops out at just about 350 clean watts into 4 ohms. Not that it's my goal to push my amp to its limits or anything. I'm imposing limits and deciding how much closer I should move the MLP to the front stage.

    Quote Originally Posted by davef View Post
    Also, be sure to run them full range when you get the chance and let me know your thoughts on the bass response.

    I agree, the imaging and detail is fantastic and many others have commented on how well they reproduce vocals. Don't be afraid to turn them up
    Oh I've been playing them full range and crossed over, however I am a little bit afraid of turning them up due to my seating distance, which is 15'. I calculated (by "I", I mean my friend who put the spreadsheet together ) I would need about 660 watts to hit reference level peaks with 1 speaker, so 330 watts for both?

    Calculated results based on Ascend specs, for one single speaker:

    Input data required: Input data Unit
    1) Speaker nominal impedance (Ohms) 4.00 Ohm
    2) Sensitivity in dB/2.83 V at 1 Meter 90.00 dB
    3) Seating distance (1 foot = 0.3048 Meter, 1 Meter = 3.281 foot) 4.57 Meter
    4) Room gain for speaker placement near walls/corners, enter 0 to 3 dB max., to err on the conservative side 3.00 dB
    5) Desired additional amplifier headroom (dB) Recommended minimum is 3 dB
    6) Target SPL - THX reference is 85 dB, with 20 dB of headroom 105.00 dB
    Calculated values from the input data: Calculated values
    Sensitivity loss at seating distance (dB) 13.20 dB
    SPL/W at seating distance calculated from the input data 79.80 dB
    Amplifier power output based on 2.83 V and the assumed impedance at 1 Meter 2.00 Watt (W)
    Power increase in multiples needed to achieve target SPL 331.46
    Power increase in dB needed to achieve target SPL 25.20 dB
    Calculated amplifier output power required:
    For the target SPL at seating distance 663.66 Watt (W)

    I'm getting A LOT of excursion from all 3 drivers the couple of times I've tested reference level (each time with 80 hz crossover). Everything still sounds clean and I'm not hearing any clipping, but I can't tell if they're running out of steam or not and I'm kind of afraid to push them that hard.
    Last edited by Pogre; 06-13-2020 at 12:50 PM.

  3. #3
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    Default Re: Sierra Ribbon Towers and Safe SPL

    I think this is 660 watts for each speaker not 330.

    Also, from the Tower spec page, it's 4 ohms minimum which is different than nominal. If you look at the plot on the measurements page, you'll see impedance looks to be 5 ohms up to 1KHz (with a peak to about 10 between 50 & 90 HZ), and then another peak between 1-3 Khz to about 13 ohms then from 3Khz on up around 8 ohms.

    I'd suggest moving closer or, Heaven forbid, turn it down :-)

  4. #4
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    Default Re: Sierra Ribbon Towers and Safe SPL

    I usually stay out of thread in regards to "reference level" because the term has lost its meaning, and I don't fully grasp the infatuation with it. Reference level was developed as a movie mixing standard for sound in commercial theaters.

    There are even some old forum posts on the internet that has Tomlinson Holman (the TH in THX) stating that reference level in a home theater is too loud because the smaller space. I think he said it should be 4-6 dB lower. Also, reference level in a home theater is the major cause of sibilance. To me, this is clearly audible as you turn up the volume on most movies to "reference".

    In fact, as the volume gets louder past a certain point, the worse your ears get at hearing/discerning "quality".

    Mixing for a commercial theater vs home is quite different, and I have been told that not many movies are remixed for home release.

    As for music, my understanding there isn't a reference level.

    OK...off my soapbox.
    -curtis

  5. #5
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    Default Re: Sierra Ribbon Towers and Safe SPL

    Let me simplify then.

    I just want to know how loud is too loud for these speakers to handle. A max spl at 1 m would be enough for rme to calculate the rest. Thank you.

  6. #6
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    Default Re: Sierra Ribbon Towers and Safe SPL

    Quote Originally Posted by Pogre View Post
    Let me simplify then.

    I just want to know how loud is too loud for these speakers to handle. A max spl at 1 m would be enough for rme to calculate the rest. Thank you.
    I think that would be whatever these two numbers get you at 1 meter:

    Maximum Continuous Power* 300 watts
    Maximum Short Term Peak Power* 500 watts
    Last edited by curtis; 06-14-2020 at 08:15 AM.
    -curtis

  7. #7
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    Default Re: Sierra Ribbon Towers and Safe SPL

    Quote Originally Posted by curtis View Post
    I think that would be whatever these two numbers get you at 1 meter:

    Maximum Continuous Power* 300 watts
    Maximum Short Term Peak Power* 500 watts
    Do you really think 300 watts continuously would be "safe"..?

    It's been my experience that continuous power ratings represent more of a melting point than an actual recommended continuous max power. I DO NOT plan to pump 300 watts into any speaker continuously. I'm setting my volume limit on my Marantz so that NO ONE will be able to turn it past what would be "safe" levels. I'm curious what that is and if I'm pushing any limits right now.

    Look, I have a big room and like it loud sometimes. I have no problems with my Ultras reaching good spls and quite frankly it was of no concern to me at all with them. They're bigger speakers tho. When I turn the Sierras up to the same volumes I don't like the excursion I'm seeing. Perhaps I'm worrying over nothing. Not sure tho because getting a straight answer is proving to be extremely difficult. I'm still within my return period and some of the replies here have me considering possibly sending the Sierras back. I want speakers that can safely hit higher spl in a large room without worrying about blowing a driver. To that point, the tweeters seem to be handling things very well.

    I realize too this is a public forum and I'm not dealing directly with Ascend, so I guess I'm expecting too much. From now on I'll leave the technical questions to people qualified to answer them. I did also send an email to support when I posted this thread so I'll wait for a reply there.

    Thank you?

  8. #8
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    Default Re: Sierra Ribbon Towers and Safe SPL

    Quote Originally Posted by Pogre View Post
    Do you really think 300 watts continuously would be "safe"..?
    Honestly, I have no idea, but I also don't have the need.

    The wattage are numbers that Ascend has spec'd. If you think they are untrue, then that is another issue.

    Here's my take: It is about overall enjoyment. If it worries you, and it isn't something you can adjust your thinking to accommodate, then it detracts from your enjoyment, and you should look for something else.

    Another subjective data point: I have been in Ascend's demo room, and have heard a pair of Sierra-2's hit a 102 db peak with an ADA PTM-6150 amp...spec'd at 150wpc. Fullrange.
    -curtis

  9. #9
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    Default Re: Sierra Ribbon Towers and Safe SPL

    Please let us know what support tells you.
    3.2, Ascend Acoustics Sierra Towers with RAAL ribbon tweeters and $20 McMaster ‘threaded-stud bumper feet’, Ascend Acoustics Duo LCR center, dual SVS SB-3000 subs, Outlaw 2200 monoblocks, Denon X3500H

  10. #10
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    Default Re: Sierra Ribbon Towers and Safe SPL

    Quote Originally Posted by curtis View Post
    Here's my take: It is about overall enjoyment. If it worries you, and it isn't something you can adjust your thinking to accommodate, then it detracts from your enjoyment, and you should look for something else.
    Here's my take: The more information I have, the better. Then I can make informed decisions to "adjust my thinking", tho what I'm really doing is adjusting my expectations (and possibly volume levels). Not sure what it is about my thinking that needs adjustment. I just want to protect my new speakers.

    The speakers sound wonderful. The only thing detracting from my enjoyment is not knowing. I'm weird like that. I like to know stuff.

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