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  • B652 Modifications- Upgrades?

    I just bought a pair of these for my father for Christmas, and couldn't resist hooking them up to the little T amp included in the "bundle" and I have to say, they aren't awful. In fact, I think they do have some possible room for improvement. What do you think about replacing the tweeter with the inexpensive Dayton Air Motion Transformer tweeter? And then replacing the woofer with either the 6 1/2" buyout woofer, or possibly something else. (I have some Vifa P17's and P18's and some Chinese knockoffs laying around...I know it's probably not worth it....but I want to go for it anyway. Any ideas, or comments? What do you guys think the Dayton AMT tweeter would do for the sound? Could they keep up? Is the "buyout" 6 1/2" poly mid-bass an "upgrade" or am I simply stepping sideways?

    What about crossover? I understand the buyout woofer can be run without any crossover, what would you put on the AMT? Anyone have a design for a crossover to these which would work? Just textbook is fine, and I guess a high order is best?

    Any help in improving the B652 is greatly appreciated...plus it's a little project I could do with my Dad, who is in a Retirement Home, but still loves excellent sound. I made a pair of Zaph Bargain MTM's using the MCM 55-1855 and Seas tweeter, which he loved, but he couldn't have the 100 watt per side receiver and those speakers in his room......but I think this little setup will be just fine....I just want it to sound as good as possible without breaking the bank...

    Oh....I do know of Zaph's crossover changes, but that is for a different version of these speakers than current production,,,,or maybe I could try them....oh and how about the buyout tweeters ...they are 2 7/8", but may be the same tweeter already in the BR......I just am looking for ideas...

    Thanks

    Ideas?

  • #2
    Re: B652 Modifications- Upgrades?

    I believe the 6 1/2" buyout driver is the same driver used in the B652s. A tweeter replacement would mean a new crossover would need to be designed.

    Comment


    • #3
      Re: B652 Modifications- Upgrades?

      It's just my opinion, and I'm just a novice, but I would treat this set for what it is... a budget-priced speaker/amp combo capable of decent casual listening during poker games and while working around the house. I've read that Leroy is correct... the 6.5" buyout woofers are the very same as in the B652 speakers. I'd just enjoy them for what they are.

      BTW, I bought this exact set as a Christmas gift for a buddy who likes to play music through his iPhone during poker games. This will definitely be an improvement over that built-in iPhone speaker!! So, even though I "technically" bought these for him, it's as much for me too. That iPhone micro-speaker sounds like sh..... :D
      "We are just statistics, born to consume resources."
      ~Horace~, 65-8 BC

      Comment


      • #4
        Re: B652 Modifications- Upgrades?

        OK......but IF a guy were to buy the el cheao Dayton AMT's, what would the textbook crossover components be? I am assuming running the woofer either as is, or running it with no crossover...in other words,crossing over and protecting the Dayton AMT's at what point, and using what components?

        Comment


        • #5
          Re: B652 Modifications- Upgrades?

          If the link below goes to the tweeters you are talking about, look at the review by Doc Jones, who used these as additional super-tweeters in the B652 and describes his crossover and the stand. He likes 'em.
          http://www.parts-express.com/dayton-...8-ohm--275-095

          Comment


          • #6
            Re: B652 Modifications- Upgrades?

            I'm not sure I would add a tweeter that costs more than the speakers... I built .5 cf boxes for mine. Big improvement. If they are still the same as the ones I bought 3 years ago then they just have a cap on the tweeter. Adding a L-pad or just a resister before the cap can bring down the tweeter level if it is needed.

            Comment


            • #7
              Re: B652 Modifications- Upgrades?

              Yup, me too Duane, but with Zaph's XO. Took the power handling hit. I've tried some ~ .38 cf boxes too. Half-way "compromises". You just can't let the woofer go so high into break-up range when the tweeter can play nearly an octave and a half lower. Don't try putting a Vifa BC25TG15-04 in the top hole with Zaph's XO. You'll be ruined. It actually sounds like a speaker.

              Comment


              • #8
                Re: B652 Modifications- Upgrades?

                If you try to use textbook formulas, you're using a fixed number like 4 or 8 ohms, for a number that varies. No driver is ever a constant impedance across its useable freq. range, so if you use say, 8 ohms in your "formula", it will not cross where you "assumed" it was going to. It could be 10, 12 15 or maybe 20 ohms at your chosen cross-point. You might be able to get a marginal result if you can find the impedance plot/graph and take note of what the impedance is at the crossover frequency. That will get you closer. I think PE has those simple textbook calculators on the site here, so find the impedance at whatever freq. you're using and use that number in the formula. I just got a pair of those speakers for my nephew for some background tunes in his kitchen. There was a tweeter recommendation, but I can't recall right now. The best improvement (without changing drivers and XO) came from adding in a couple of internal braces, side-to-side and front-to-back and some correct acoustic damping material in the right amounts. I just used some 1" thick Dacron quilt batting to line the inside. We listened before and after, I took my usual evaluation notes, and we both agreed that bracing and acoustic damping made a noticeable improvement. Not night/day, but you could hear it with the bass and midrange being a little more defined and less fatiguing. If you do make any mods, let us know what you think...more opinions/impressions are always good.


                John A.
                "Children play with b-a-l-l-s and sticks, men race, and real men race motorcycles"-John Surtees
                Emotiva UPA-2, USP-1, ERC-1 CD
                Yamaha KX-390 HX-Pro
                Pioneer TX-9500 II
                Yamaha YP-211 w/Grado GF3E+
                Statement Monitors
                Vintage system: Yamaha CR-420, Technics SL-PG100, Pioneer CT-F8282, Akai X-1800, Morel(T)/Vifa(W) DIY 2-way in .5 ft3
                Photos: http://custom.smugmug.com/Electronic...#4114714_cGTBx
                Blogs: http://techtalk.parts-express.com/blog.php?u=2003

                Comment


                • #9
                  Re: B652 Modifications- Upgrades?

                  You already have them so that's something to consider, but in general, I don't see the point of buying cheap speakers and then spending 2x the price trying to make them sound like better speakers. Just buy better speakers. If you have the itch to modify things, buy a kit or build your own instead.

                  The B652 is what it is, and to be substantially more apparently requires a larger box, bracing, a better crossover, and a better tweeter. But hey, you can keep the woofer and terminal cup. ;)

                  Comment


                  • #10
                    Re: B652 Modifications- Upgrades?

                    Zaph's mod put's some BSC on the woofer and some woofer shaping (Zobel-like), moves the XO from a 1st order at about 7Khz (!!!) to a 2nd order @ closer to 2.5Khz, which the tweeter can handle. A non-resonate enclosure bigger than the about 6.2 net stock tightly stuffed above the woofer with loose fiberglas (I used nearly 2 lbs.) and some very very thin fiberglas behind the woofer (mattress topper would be fine) in either a 15 or 12 Liter enclosure (net volume) with the stock drivers make a big SQ improvement at the cost of "power handling". A 11-12L enclosure gains you nearly 10 Hz lower F5, about 5Hz lower F3. The 15 liter enclosure nets you a full 10Hz lower F0, F3, and ~12-14 Hz F10. It also helps tame that nasty 100-200+ Hz hump in a small box. With everything I've done to them, they're just passable audio speakers. They make decent side and upper front "surround" speakers, and a pair of them can pass for a center channel.

                    Comment


                    • #11
                      Re: B652 Modifications- Upgrades?

                      I don't intend to burst the OP's bubble but... building new enclosures plus redesigning and replacing the crossovers seems inappropriate for these drivers. I'll just restate that I think these should be left alone and used as inexpensive systems for very casual listening. I can't see going to all that trouble and expense for these. I dunno... maybe just lower the crossover to 5KHz with a single coil on the woofer and change the cap value on the tweeter?

                      The above stated, I do intend to build arrays with these same buy-out woofers, 3" buyout mids and cheap 50 cent tweeters. But those will be 8 feet tall and mounted on unfinished open back 4x8 plywood sheets. I already have some MCM bi-amp plates with built-in crossovers for the 3's and tweets and Yung SW plate amps to run the 6.5's. It's play... but hoping the great multitude of drivers used will compensate for the low limited excursion abilities of the drivers. We'll see...

                      Again, I don't intend to burst the OP's bubble but if one is going to put so much time and money into making some nice MT speakers I think spending a bit more on drivers makes sense because the single drivers will be pushed much harder than in arrays. Arrays are a different animal because so many drivers are needed that the cost could run up to thousands and excursion is kept to a minimum so maybe these will be fine.
                      "We are just statistics, born to consume resources."
                      ~Horace~, 65-8 BC

                      Comment


                      • #12
                        Re: B652 Modifications- Upgrades?

                        I didn't address the woofer. The buy-out woofer and the OEM woofer in the B652's are just about the same beast. To get much improvement from a better woofer, you need a bigger enclosure, so for ~$150 in parts, you can build Paul Carmody's ClassixII's. I think it's my favorite "get you feet wet" in DIY design. It's easy to build, and it has the eye-opening sound that store speakers don't have until the "listening room" price range.

                        Comment


                        • #13
                          Re: B652 Modifications- Upgrades?

                          Sure, spending even $20 more for a couple new tweeters defeats the price-point purpose. For the same price as the stock '652s, you could get a raw knock-down kit and start with a solid foundation...which will offer much more improvements and benefits regarding SQ than using the stock boxes. Those "mods" I incorporated did not cost hardly anything. Most have scrap left over and laying around, plus some extra chunks of acoustic damping. I wouldn't go out and buy some dowels and poly/Dacron fill for these speakers, but I have a lot of that stuff accumulated over the years. It took about 15 minutes, I got to show my nephew how to do it, and he noticed a bit better SQ by just doing those 2 things. So I mainly do it to show skeptical sorts how much is left on the table just by the omission of those two simple things. I never thought about spending more on tweeters and/or XO parts after I examined the cabinets. But fiddling around with them could lead to learning a little, so that part has value. Fine for two braces and some Dacron batting, but anything beyond that would be better used & spent with a solid foundation/cabinet to begin with.


                          John A.
                          "Children play with b-a-l-l-s and sticks, men race, and real men race motorcycles"-John Surtees
                          Emotiva UPA-2, USP-1, ERC-1 CD
                          Yamaha KX-390 HX-Pro
                          Pioneer TX-9500 II
                          Yamaha YP-211 w/Grado GF3E+
                          Statement Monitors
                          Vintage system: Yamaha CR-420, Technics SL-PG100, Pioneer CT-F8282, Akai X-1800, Morel(T)/Vifa(W) DIY 2-way in .5 ft3
                          Photos: http://custom.smugmug.com/Electronic...#4114714_cGTBx
                          Blogs: http://techtalk.parts-express.com/blog.php?u=2003

                          Comment


                          • #14
                            Re: B652 Modifications- Upgrades?

                            The tweeter isn't really a total pig, it's just crossed to too high as built. It's a single 5.6 uf cap going to a 4 ohm tweeter so by P-E's own calculator, that's about 7KHz. The woofer can't play half that high without hurting your ears, and the tweeter can play 3.5 KHz or a little lower fine. Soooo, just going with cheesy 1st order "textbook" cross-over, L1~.6uH for some BSC and C1~11mF will be better than nothing. You really can't do much harm. Here, a small (20 gauge) inductor is your friend.

                            Comment


                            • #15
                              Re: B652 Modifications- Upgrades?

                              Originally posted by johnastockman View Post
                              Sure, spending even $20 more for a couple new tweeters defeats the price-point purpose. For the same price as the stock '652s, you could get a raw knock-down kit and start with a solid foundation...which will offer much more improvements and benefits regarding SQ than using the stock boxes. Those "mods" I incorporated did not cost hardly anything. Most have scrap left over and laying around, plus some extra chunks of acoustic damping. I wouldn't go out and buy some dowels and poly/Dacron fill for these speakers, but I have a lot of that stuff accumulated over the years. It took about 15 minutes, I got to show my nephew how to do it, and he noticed a bit better SQ by just doing those 2 things. So I mainly do it to show skeptical sorts how much is left on the table just by the omission of those two simple things. I never thought about spending more on tweeters and/or XO parts after I examined the cabinets. But fiddling around with them could lead to learning a little, so that part has value. Fine for two braces and some Dacron batting, but anything beyond that would be better used & spent with a solid foundation/cabinet to begin with.


                              John A.
                              Good points, John. I'm sure I can talk my buddy into the dowel rod reinforcement and extra poly fill mods... especially if I provide the materials. BTW, I'm just a novice but I'd guess those two mods are the best time/money spent on these.
                              "We are just statistics, born to consume resources."
                              ~Horace~, 65-8 BC

                              Comment

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