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Bass driver to mate with a 6 dB @ 35 Hz boost circuit

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  • Bass driver to mate with a 6 dB @ 35 Hz boost circuit

    Looking for a driver recommendation. I have a Dayton Audio SPA250 plate amplifier that I would like to make best use of in a bass bin to compliment a pair of original NHT SuperZeros. By make best use of, I'm thinking present with a 4 ohm load (more power) and use a driver, or drivers, as in a dual opposed configuration, in a sealed enclosure of appropriate size to mate with the amp's switchable boost circuit, 6 dB @ 35 Hz, thereby allowing the enclosure to be more compact. Per Stereophile's review, the SuperZeros are -6 dB at 88 Hz, which is why I use the term bass bin -- I'm more concerned about the quality of bass at 90 Hz than I am the quantity of bass below 32 Hz. Price is not the determining factor, and music is the goal, not LFE Your suggestions are appreciated.

  • #2
    https://www.youtube.com/watch?v=BdF7nTU_QOQ

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    • #3
      What size enclosure do you have in mind? Also, what SPL levels are you targeting? There are so many options, these basic questions might narrow it down a bit.

      I am happy to see that you are looking for musical bass, not just low frequency extension. I believe it is possible to have one without the other.

      I would be looking at relatively large drivers that make bass an octave or so lower than the Super Zeros in a sealed enclosure. This is where the Parts Express Optimum Cabinet Size suggestions are very useful.

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      • #4
        Using 6dB of bass boost at 35Hz to compensate for a speaker that's down 6dB st 35Hz is an option, but there are two caveats to consider. 6dB of boost increases power by a factor of four, which the amp needs the capacity to provide and the voice coil needs the capacity to handle. 6dB of boost also doubles cone excursion, which the driver must be capable of at the intended output level.
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

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        • #5
          The 10" & 12" (4ohm) HO subs look pretty good in your pass band. The 10" in 0.5cf, but I'd probably go w/the 12" in 1.0cf (closed).

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          • #6
            Originally posted by dstmbgh View Post
            Looking for a driver recommendation. I have a Dayton Audio SPA250 plate amplifier that I would like to make best use of in a bass bin to compliment a pair of original NHT SuperZeros. By make best use of, I'm thinking present with a 4 ohm load (more power) and use a driver, or drivers, as in a dual opposed configuration, in a sealed enclosure of appropriate size to mate with the amp's switchable boost circuit, 6 dB @ 35 Hz, thereby allowing the enclosure to be more compact. Per Stereophile's review, the SuperZeros are -6 dB at 88 Hz, which is why I use the term bass bin -- I'm more concerned about the quality of bass at 90 Hz than I am the quantity of bass below 32 Hz. Price is not the determining factor, and music is the goal, not LFE Your suggestions are appreciated.
            The RS270P-4 might be an option for you.

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            • #7
              Thank you for the comments and questions.

              I have been using this plate amp for a number of years in a bass bin paired with the SuperZeros, but without the bass boost circuit engaged. I was living in a small apartment and in order to conserve floor space I built a bass bin that matched the footprint of and was placed under an old RCA oak console TV. A grill made with oxblood vintage grill cloth extending up and covering the swivel base, and some Minwax Expresso Polyshades coating both TV and bass bin made a very handsome pairing that looked originally made for one anther. Because of the proximity to the CRT picture tube, I had to use shielded drivers, and by that time there were few still on the market. I came across the 65 liter EBS alignment that Fbov/Frank used in his build of the Natalies with the RS180S-8, and, while one would normally not think of the RS180 as a driver for a bass bin, this suited my needs well and sounds great. When Phil Bamberg came over with his Omnimic to help me fine tune adjustments, he commented that he would have had no idea he was listening to two 7" drivers. With Frank's EBS alignment and the gain from being situated at the floor, the bass was that good. Phil also remarked, "I had no idea the Superzeros sounded that good." I'm still listening to this combo, but I've since ditched the CRT TV. I mention this to convey that I've had enough bass and enough power. Again, the bass boost is not switched in, and the 8 ohm drivers are connected in parallel for a 4 ohm load (amp is rated at 250 watts at 4 ohms).

              So, now the RS180s are unhappy -- they feel their magnet shielding is obsolete with no CRT close by, and, knowing they are far superior drivers to the inexpensive ones in the SuperZeros, they're resentful, like one being upstaged by a less talented sibling. It's just not fair. So I want to help them realize their full potential, and Wolf has suggested that Lou C's Cryolites might be just the ticket. Looks like I can still get the Neo 3PDR's from a Michigan supplier, and Paul K has graciously provided a slightly tweaked version of the MLTL he used for his Brillante, or I could use Paul C's box alignment for the Amiga. Perhaps then the RS180S's will feel like they have achieved their destiny and will stop whining at me.

              Then...I can use the amp I already have to make something ideally suited to the SuperZeros, which are compact value busters. I'm considering that the bass boost circuit could help with compactness without sacrificing extension too much, but, as helpfully pointed out above, the trade off is power consumption and added excursion. The thought went through my mind to use something like two 10" RSS265HO-44 dual opposed in 1 cu ft and wired voice coils parallel and drivers series for a 4 ohm load, but $300+ for drivers is probably over-reach to pair with the inexpensive SuperZeros (so says my most rational mind). While I am not locked into any specific size, I think I want to keep with the compact theme of the SuperZeros, as this set may get passed along to a family member for whom pragmatic concerns out way performance. I could dispense with the notion of using the amp's boost circuit and use my amp with Jeff's B's Baby Boomer sub, maybe with the PR's instead of the port, and I would achieve a cost/performance/size that's in line with the SuperZeros.

              What would you do?

              It's been suggested that I have a tendency to over think things. Hmm, let me think about that.

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              • #8
                Looks like this is Parts Express's suggested package/pairing for the SPA250 with bass boost. Question is, given that a 500 watt plate amp is also suggested, is the 250 watt barely enough, as in the caveat shared above by Bill? Might I be better advised to dispense with the idea of using the boost circuit given I "only" have 250 watts?
                Dayton Audio 10" Reference Series HO Subwoofer and Cabinet Bundle

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                • #9
                  This is a weird coincidence. My friend just bought a system at an estate sale. NHT super zeros, a Carver receiver, and an NHT sub with amplifier. We set it up in my living room which is roughly 13 x 18 I think. Speakers about 4' out from the wall, and the sub near a corner. We got it dialed in to our satisfaction in about two hours. The Carver has a mid-range tone control, along with bass and treble. I felt the zeros were a little forward sounding, but the tone controls took care of that nicely. This setup was very good in my opinion with classical. I'm not sure if the sub amp high-passes the mains, but I suspect that it does. The sub low-pass adjustment was set at 50hz. We tweaked everything by ear using some familiar rock, and jazz type recordings. We didn't push the SPL more than about 85dB. I think the zeros could get damaged if played like I play my larger speakers.

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                  • #10
                    I feel that deep down you really want to make all new speakers.

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                    • #11
                      Rpb, I've enjoyed my SuperZeros a lot. I first heard them in a used Hi-Fi shoppe playing Miles Davis, Kind of Blue. Think I paid $140 for them. My wife wanted smaller speakers in the family room which at the time were occupied by the first speakers I ever built from parts obtained from McGee Radio -- Rockwell 8" with butyl rubber surround paired with the then ubiquitous Motorola piezo tweeter in a 1.6 cu ft cab with a 12" passive radiator. Those went to Alaska with my best friend where they are still in use. For the price the SuperZeros do what they do well, but there's a complete absence of middle and low bass, and, yes, there's some excess energy between 1300-2300 kHz, which -1 on my treble tone control nicely takes care of. As an aside, my friend in Alaska recently asked about upgrading the drivers and using the cabinets and I've recommended Wolf's Zingers (with Paul C's original larger cabinet tuning).

                      Djg, guilty as charged (smiling and raising my hands). It kinda bugs me that the RS180s are relegated to playing two octaves when I know that they can do so much more, and do it well (Modula, Amiga, Cryolites, etc). And the cabinet they're in is now out of place without the TV which sat on top. My SuperZeros are still playing away on some nice custom stands I made for them out of stair tread (1 1/8" particle board) which I showed in Grand Rapids at the Meniscus gathering in 2016. So, yes, before I build something completely new I'll optimize what I have. This is what we do, right?

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                      • #12
                        Sure, I made speaker stands out of stuff laying around.

                        I think RS180 towers of some sort would be great.

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                        • #13
                          Originally posted by rpb View Post

                          The RS270P-4 might be an option for you.

                          Why not model the boost transfer function and turn the active portion on and show the difference it makes?
                          Click here for Jeff Bagby's Loudspeaker Design Software

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                          • #14
                            Originally posted by Jeff B. View Post

                            Why not model the boost transfer function and turn the active portion on and show the difference it makes?
                            At the time I posted, no one could upload pictures. This picture was already in one of my threads. Although not perfect, the boost probably would extend the bass pretty well.

                            Guess I could do it now, but I think the OP might be looking for more output than this driver would provide.

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