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Building Around a Hivi Q1R Tweeter

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  • Building Around a Hivi Q1R Tweeter

    Hello all, first post and it's a marathon, so here we go!
    Earlier this year after completing my first set of DIY speakers (Overnight Sensation TMMs) I impulse bought a pair of Hivi Q1R tweeters in anticipation of completing a project I saw on diyaudio com. After enjoying my OS TMMs more and more, and seeing the impressive results other people were getting for less money than the woofer budget in the linked project, my ambition for that protect stalled.

    Now I haven't built anything for awhile and I'm getting the itch, but whatever I build needs to use these tweeters that apparently aren't very popular except for as direct replacements in Acoustic Research AR3A speakers. I've had multiple ideas cross my mind, but I'm an extremely indecisive person and am hoping for some discussion to help me narrow this down/start over. Those ideas are:
    • A TMM with the Dayton TCP115
    • A TMWW with Vifa TC9 and Dayton TCP115
    • An MTM with either the Peerless 830656 (iron driver at InDIYana awhile ago), Dayton DC130BS-4 (TriTrix drivers), SB Acoustic SB13, or SB Acoustic SB16
    • A TMW with the TC9 and any of the woofers from my MTM list
    • Anything else I haven't thought of but definitely exists
    What I'm looking for:
    • Preferably a floor standing tower but maybe an MTM on a stand
    • 2 way or 2.5 cascaded crossover preferred but entertaining the idea of a 3 way
    • Something with clear mids and comparable amounts of bass to my OS TMMs that can integrate with the Q1R
    • Something oriented towards music listening, of which my tastes are a wild card. Equal parts Rock and electronic with some blues and classical thrown in. They will be pulling double duty, being used for TV watching as well but I'm more concerned with musical performance as opposed to theater
    • Passive crossover
    My limitations are, in my mind and quite obviously by definition, a bit limiting:
    • Roughly $100 for drivers. SWMBO would not be happy to see more than this show up on the doorstep when I "already have a perfectly functioning set of speakers".
    • Somewhat slim profile, trying for a baffle of around 6 inches but no bigger than 9 and a height staying around 40 inches or a bit less. The first comment when I placed the OS TMMs in the living room was "oh, they're kinda big". Definitely realized I should've started with something way bigger because I'm screwed now.
    • No subwoofer to help on the low end
    • Placed no more than about 2 ½ feet from the front wall of a 15 x 17 room with 7 foot ceilings, a hallway off the back wall, and a similarly sized kitchen off roughly half the left "wall"
    Whatever I do build will be played from a Marantz SR7400 AVR. I've been walking myself through PCD and Response Modeler with a couple of the aforementioned drivers (and tons of reading on this forum). It is extremely generous of Mr. Bagby to offer such incredible programs for free!

    So, apologies for the extremely long post, but am I on a reasonable path with any of this? Is there another option/options I'm completely missing? What would you do different with these constraints? Feel free to tell me I'm off in the weeds, that's kind of how I feel about it anyway!

  • #2
    The TCP115 is a very impressive little driver. If you can get help with the crossover to get things right I think your TMM option using it would sound best of your options. If you can live with a 95 DB max SPL (which is pretty darn loud} the Q1R and a single TCP115 might satisfy.


    • #3
      I have a pair of the HiVi D6 that came with a kit, the kit uses the Q1 tweeter. I'll let them go for a very good price.
      Don't listen to me - I have not sold any $150,000 speakers.


      • #4
        I've been wanting to use some sb drivers. Since the tcp115 and the b4n have the same outer dimension the baffle could remain the same as the OS tmm possibly offering more AWA acceptance. A 9" baffle will fit a 6.5 or maybe a 7" driver.


        • #5
          Johnny's HiVi's would be a great option - he always seems to offer a deal that's hard to turn down. Other than that, the TCP115 isn't bad - I'm listening to some right now and I'm surprised how good they sound (now that I have them in the right box!). Not super detailed, but very easy on the ears. That said, at the clearance prices on those SBs out of Wisconsin, there's no contest there. Even using 2 of the TCP115s, the 6" SB has almost 3 times the displacement and should play a little lower. Yes, you will need a bigger box, but it'll still be well under .75 cu ft. You could always make it a nice slim floorstander. Let your wife pick some nice hardwood and stain for the baffles - then she's involved in the project.
          Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.


          • #6
            No help whatsoever ...

            Generally it's best to have a tweeter w/a small OD faceplate (or at least the smallest possible). HiVi makes some of the largest dia. tweeter faceplates out there (inc. yours).
            Looking at the (probably) min. recommended Fc (of 2.5kHz) for that Q1R limits you (by conventional ROT) to using 5", MAYbe 6" midbasses.
            The Q1R has a low power-handling (it says 15wRMS) AND a low sensitivity, of 89dB. Too much extra woofer capability would be a waste.
            A PAIR of TCP-8s would really like the (SIZE, internally) 0.23 cf Denovo knock-down box, but due to the LARGE Q1R faceplate, you'd need a baffle at least 15" tall. The Denovo is only 10".
            I think these could probably reach into the mid 50s range (possibly not quite as low as your OSes?) ?
            Would they sound better? - not sure I'd call it an upgrade, but maybe?


            • #7
              Thanks all for the replies! The TCP115 option I think has been consistently towards the top of the list in my head, but I keep wondering if I could get away with a slightly larger baffle and escape the wrath of SWMBO. She's forgiving and understanding enough that if I follow the advice from tom_s and let her be involved in baffles and colors she'd be just fine. I messaged Johnny on his Hivi drivers, as I always like the sound of getting a deal. I understand (I think!) what you're saying though, Chris, it would be a shame to waste a bunch of driver potential if the tweeter can't follow suit. I might be inclined to switch out the tweeter and redo the crossover for something different down the road, who knows! I do have one question on what you said Chris, when speaking of the crossover frequency are you saying I'd be limited at those woofer sizes because the larger woofers would have issues reaching up that high to meet that tweeter? I still have much to learn!


              • #8
                My $.02.

                I am not familiar with that tweeter but it appears Chris Roemer is and that it doesn't reach down very far so the woofers have to reach up higher to meet it. Generally speaking, the smaller the woofer the higher up it will reach in frequency, although other factors also come into play. So the answer to your question is yes.

                Just throwing this out there. Maybe go with a different tweeter for the mains and use those hivi for the surrounds in a HT setup? Some fairly decent tweeters can be had around the $20 mark.


                • #9
                  That makes sense. Sounds like this tweeter is kind of painting me into a corner, but I'm not opposed to a challenge. That's how I learn! Unfortunately, with my financial situation combined with keeping a happy relationship, I need to use up these tweeters and I'm not allowed to put more speakers in the room; no HT surrounds for me for the foreseeable future. Personally I like the idea (my Marantz is capable of 7.1 after all!) but I fought a major battle to successfully get a bass trap in the worst corner of the room, I'm currently on the give side of the give-take relationship.


                  • #10
                    Update! I decided to go with the drivers johnnyrichards offered up, tom_s was right; the deal was too good to pass up! With that decision out of the way, it's on to box and crossover design. With a 6.8 inch OD on the woofer and 4.5 inch OD on the tweeter, best I can do on a center to center mounting is 5.65 inches (keeping it centered on the baffle, which I'm not dead set on) and a crossover frequency of 2,400 Hz. This seems to ask a bit much out of the tweeter, as Chris mentioned, but these two were used in a kit from Hivi at some point, so I'm determined to make it work. I understand following commercial manufacturer's lead doesn't exactly ensure great results, but I'm up to the challenge of getting something to work. One benefit to all this is johnnyrichards has already done T/S measurements on these so I can design the box to what he measured, which is apparently far off from the manufacturer listed specs. Next up, Response Modeler and a bunch of learning for me!


                    • #11
                      Nothing but good things to say about JR.

                      Off on another tangent. Have you considered adding some paintings to your listening room? For ht surround speakers you could always do some small dml panels. It may take you a bit of searching, but there is a thread where the guy actually had his wife turn them into artwork. They looked quite nice.


                      • #12
                        In case you haven't seen it yet, here's a thread from 2013 that might have some useful info for you.
                        Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.


                        • #13
                          Kornbread I agree, JR has been great in the short time we interacted ! It's funny you mention dml, I've already made a couple panels for that exact reason! But neither of us are artistic so they're raw and I hit a snag figuring out how to hang them on our rear wall (wood paneling in a rental) so they've just been sitting behind my AVR, only getting dragged out on occasion when the better half is out of town.

                          tom_s that's a good thread! Working my way through it right now.


                          • #14
                            Alright I've put in some Response Modeler and PCD time, thought I'd share some progress. The woofers, to be specific, are HiVi D6.8IIB woofers originally meant for a kit with the Q1R. In a post johnnyrichards made after measuring these woofers a few years ago, he got a Qts of 1.26. From what i've read on this forum and others, that is far too high for a vented enclosure, and is higher than most things I've seen in a sealed box. I don't have room space (or funds) to turn this into an open baffle design, so my next thought came when I read a thread mentioning aperiodic enclosures. It seems like an interesting option, but for a cost of $30 per vent. For now, I'm modeling in a sealed box 36"H x 7.5"W x 5.5"D out of 3/4" material for a volume of 897 cubic inches or 14.7 liters. I tried to watch xmax limits, but that seemed essentially frutless at any levels past 90 db. I'm not looking to play these very loud very often, but I'm definitely open to suggestions. In any case, using Response Modeler, I modeled the box and the baffle with a 3/4" roundover, extracted minimum phase, modeled the tweeter on the baffle and extracted minimum phase, and moved to PCD.

                            Using the FR listed for the D6.8B on the Parts Express website, the woofer does some nasty things around 2,500 Hz, so I tried crossing it over all the way down at 1,000 Hz (3rd order) to get rid of part of the issue, and put an RLC (notch filter?) on it to tame the other other peak up high. I experimented with crossing the tweeter higher and 3,800 Hz 2nd order ended up surprisingly flat. I feel like this method is absolutely wrong, having such a massive gap between electrical crossover points, but the response is closer to flat than I expected at this point. My only complaint is the very end of the tweeter response,

                            My suspicion starts at the filter transfer functions. My extremely basic understanding was that these were supposed to be relatively smooth until the crossover point, and then fall/rise with similar slopes. My filter transfer functions are anything but smooth. My next suspicion is the impedance graph. It looks very oddly shaped, multiple peaks, but I'm not too sure what is ok to see here. I'm using the manufacturer FR for both woofer and tweeter, as I couldn't find any other measurements that weren't in a box/on a different baffle and I don't have measuring equipment. My woofer impedance was extracted from Response Modeler after box and baffle modeling, but I didn't know which impedance plot to use from the manufacturer spec sheet so I know I have more work to do on that end.

                            I'll try to attach the FRD plots I'm using and some screenshots of my PCD session. Anybody have suggestions/corrections?
                            Attached Files


                            • #15
                              You need to enter acoustic center offsets and coil dcr values. The drivers are not coincident, and the coils have inherent resistance. The Q1R is likely not going to like being xover so low. For aperiodic box model, make Ql =3, and just stuff a floor drain with foam for a much cheaper vent.
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