Openly Baffled!

uglymusicuglymusic
edited October 2011 in Loudspeakers
Recently I went over to Jim's place for a bit of hi-fiing (Jim is sometime of this parish).

I took my Young and PSU, James' Lightspeed, and my dicky Eva and PSU. 

Jim's system included a pair of home made Open Baffle speakers based on Lowther full-range drivers and Eminence (I think) bass units. These were driven by a modified Leak valve amp (Lowthers) and a pair of DIY SS monoblocks (bass units) and a Behringer active crossover. 

Front ends are a DIY turntable and the very best TT I've ever heard (no kidding!), a Garrard 401 in a custom plinth with heavily tweaked Rega arm and I don't know what the cartridge was. This thing plays rhythms like the very best digital. If I still had my vinyl, I'd be looking for a 401 and trawling Jim's knowledge.

Anyhow, the OBs were very impressive, particularly on brass and voices, but there was great spatial ability and bass that went way down when there was need to. All with great timing and drive. These speakers seemed at home with all the music we had time to try them with, and with the analogue and digital sources.

My main problem was a difference in character between the bass end and the rest of the frequency spectrum. Jim agreed, and the day after substituted another pair of SS monoblocks (nearly identical to the other pair) for the tube amp. He tells me it's cured the variation in character, but there are some things he prefers about the valve amps.

Meanwhile, I'm very impressed with my first encounter with OBs. They appear to do many of the things I like about horn speakers, but without the cabinet-derived problems. There may not be that last iota of immediacy you get with horns, but everything else seems to do its thing better. And, although the OB world is generally aligned with the high efficiency/low output crowd, there seems no reason why a less sensitive driver shouldn't be chosen to make a better match for my powerful TDSs.

I'm very tempted by the OB route.

Has anyone else here experimented with OBs? Or, indeed, does anyone run OBs?

Comments

  • AlanAlan
    That's pretty interesting Dave, I have never heard a 'good' OB setup (but I've only heard a few). What put me off was the music being projected rearwards and then forwards again off the walls, which gave an impression of scale but was off-putting after a while. How does Jim's rig manage that sort of thing?

    I feel that the cabinet is one of the weakest parts of any speaker (interesting your comments on horns above), but attempting to neutralise it with bracing or plates of rigid material doesn't always yield good results - to my surprise & frustration in the past!

    Removing the cab altogether sounds liken an elegant solution (as does an OB line array in each corner of the room...), and I always wondered about mounting speaker drivers flush into the wall too!

    I have also heard pretty much all speakers benefit from having the crossover removed from the cabinet and installed in a seperate box, but I never tried that trick.

    Speaker design often looks much like a black art to me, I'm glad Jim has found a way to get it to work well.
  • uglymusicuglymusic
    edited October 2011
    Rear reflections are seen to be a plus point of an OB, provided you can get the things far enough away from the back wall. However, Jim had found that in his room the rear reflections were interfering with the depth of the stereo image - it was collapsing back behind the baffles - so he has placed some cloth behind the wide ranger.

    Voila! The image fills the room.

    The crossover here is more than removed from the speakers. It's placed before the amps in an active configuration.

    Jim has been experimenting with speaker design for years and has amassed a lot of knowledge and experience, as well as a good range of drivers. The OBs I heard were based on - at current prices - £1.5k's worth of Lowther drive units, so you could say that Jim's designs aren't primarily for the usual DIYer's reason of saving money, but to get the best sound in his room from the drive units he likes.
  • AlanAlan
    Very impressive stuff - it seems that if you know what you are doing DIY can give the best results on any budget.
  • uglymusicuglymusic
    While Jim gets on with evolving his OBs, he and I have been for the last couple of weeks tossing some ideas backwards and forwards about designing some OBs that may work in my more restrictive listing environment. 

    I'll try to distill what we've been talking about and post it here if anyone's interested.
  • DocfosterDocfoster
    Will it make more sense after a few pints...?
  • uglymusicuglymusic
    Everything makes sense after a few pints :-)
  • DocfosterDocfoster
    Phew.
    It's not just me then.
  • AlanAlan
    Will it make more sense after a few pints...?
    ..Except Ben!

    I'm in, Dave!
  • uglymusicuglymusic
    You're in what???
  • DocfosterDocfoster
    The pub...?
  • AlanAlan
    I was referring to your distillation Dave!
  • DocfosterDocfoster
    If it's distilled, best not have as much as a few pints...
  • uglymusicuglymusic
    I was referring to your distillation Dave!
    Ah, OK. I'll get to it, sah! 
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