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Rogers Export Monitors MkII

Discussion in 'classic' started by Pulse Studio, Feb 3, 2009.

  1. Pulse Studio

    Pulse Studio TubeTech

    I have just brought the most gorgeous pair of Rogers Export Monitors from a fellow PFM'er, cheers Rick, they are in absolutely immaculate condition and finished in amazing Rosewood veneer.
    I have them stood on open frame trolly stands with spikes, these are plunged deep into my carpet and onto a solid concrete floor, room size 21' x 16', powered by a NAP250 fitted NCC200 boards and NAC32.5, driven by my AAA5.

    I thought these speakers should be idealy suited to my room size, they are stood well clear of any boundary walls to the tune of at least 3' side and back and the bass is just so bloody boomy, am I missing something here, is there a known bass bloom from these speakers, or is this just what reflex enclosures do, loads of wet, farty, one note bass with no articulate timing to the bass lines, or am I expecting too much from a late 70's speaker design, does anyone know of any mods for these classic speakers to tame this problem or should I just stuff the port to dampen it with foam or resistive load it with drinking straws ? any advice or help from anyone greatly appreciated
    Paul
     
  2. DSJR

    DSJR Between us and them

    I thought I'd answered that Paul, and any PFMer's here would regard these old BBC inspired speakers as sleepy at best with very poor pr@t zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz.

    Have you tried the cushion trick I suggested yet? it worked for me, but I'm too darn lazy to open the bloody things up yet again to take any pics.. When I do the re-wiring I'll take some and send/post a few.

    [​IMG]

    I know that response plots don't tell the whole story by any means, but the trough between 700Hz and 300KHz would send the upper mid back a bit and this, coupled with an underdamped bass (as in the BC1 and 2 also, as well as the first Rogers Studio 1) and an amp with low damping factor [citation needed here] would definitely cause the problems you're having.

    Are they playing across the room? A friends 24' x 11' room aided 'Briks really well when they were playing down the room, but they sounded light in the bass and "shouty" when playing across it. I was always told to use "properly neutral" bigger speakers across the width of an oblong room wherever possible.....

    The Export monitor dates from the mid-seventies as I recall and if yours are late seventies, they were not long for the production world, as the Studio came very soon after as a "Best Buy."

    By the way, the Studio came with T27's used as a super-tweeter, so your late pair of Exports may be perfectly correct.

    [​IMG]
     
  3. Pulse Studio

    Pulse Studio TubeTech

    Hi Dave
    Yes tried a cushion insert fitted inside each cab as you suggested, totally destroyed everything to my ears, lost most of the boom n bloom and too much else sadly. I did try stuffing the very short port with some ( only available ) plastic drinking straws yesterday evening, now this has taken them to another level, it seems to kill the bloom and has resulted in a much better controlled bottom end, still a little too much in terms of bass energy though. So my next plan is to add some additional long haired wool to the internal space behind the bass driver, this area was totally void of any filling, now it may be argued that this will increase the effective volume and therefore make it sound really bottom heavy, but I will try anyway, never really got my head around this science, but apparently it does !
    I strongly believe that the MkII's were indeed fitted with the T27 as the super-tweets, only operating above 13Khz so no nasty lower resonances to contend with, and they most definately are identical in every respect to the 3/5a tweets, so selected in-house for correct spec it seems. To be perfectly honest, I really love the mid and HF that these things are spewing out, a little more forward than the 3/5a's but couple this to the extended LF and it balances really well, and I would definately not classify them as sleepy, not with a NAP250/NCC200's pushing them, they are incredibly well behaved and well balanced even when driven quite hard, and the thing that has most amazed me is the space around the speakers, a really amazing 3D soundstage from such a large baffle area, quite something, which is why I am so intent on getting the LF to sound correct, more work to do it seems, happy days :)
    Oh BTW I will post your few bits tomorrow, been working from home today so did not get into the office to catch the postie, you will go to the ball fair prince :D
    Paul
     
  4. stugeek

    stugeek Slow-editing Nutjob

    That's just the Rogers sound I'm afraid - they'll never do rythmic bass in the same way that say a set of Missions will.

    All I can suggest doing is what I did with my Rogers - Blu-tac them to their stands, use spikes on the bottom of said stands and put a bag of builders sand on top of the cabinets.
     
  5. Pulse Studio

    Pulse Studio TubeTech

    It all sounded like sound advice until the last line stugeek, a bag of builders sand on top of the cabinets :D are you smoking something that maybe I need to share ;) I do have spikes on the stands, but they are not ideal stands, they are those open frame thingys made from 1" tubular steel, not the best I know and maybe this is where the problem lies, I used to have a pair of Target 3 column stands, HS15 I believe they were called, sadly I let them go with my Rogers LS7t's, and now regret it :( need another pair, and indeed I did place a wanted in the classifieds, nowt doing so far.
    The changes I have made so far have brought about a noticable improvement though, so not all a waste of time and effort.

    Paul
     
  6. stugeek

    stugeek Slow-editing Nutjob

    I'm using some target 1" tubular steel stands - not heavy enough IMO but one has to make do.

    But yeah, builders sand seemed to do the trick for me (and you're more than welcome to share :D).
     
  7. 337alant

    337alant Negatively Biased

    Paul
    Natural lambswool is good and I also like deflex panels for damping.
    You could also try making the port a little longer to reduce bass

    Alan
     
  8. DSJR

    DSJR Between us and them

    The cushion trick was to leave half the bass unit open to the port. When I covered the bass unit in the Harbeth HL5's I once owned, it killed the midrange details stone dead. Adding damping/wool to half the cabinet but letting the drive unit "see" the port helped me with these two speakers.. Regarding the port, the BC1 and 2 only had port holes to start with, the tuned ports came much later..

    Good luck with the Rogers'. I have some Target three prong stands (14" with open tops) on their way. If they're the ones I'm thinking of, they worked well with this kind of speakers.

    I'm sure your NCC200 equipped 250 will be fine, a chap I knew used a standard 250 with SP1's with no problem.
     
  9. Pulse Studio

    Pulse Studio TubeTech

    I will keep you to that stugeek ;) but not gonna try the bag of builders sand mate,

    Alan to the rescue, at last someone who hasn't been on any ellicit substance, the stuff I have is called Dr Baily's long haired wool, is that lambs wool, or does this mean a trip to Wales again with my shears :)
    The extra length port has been suggested by Dave ( DSJR ) I am reluctant to hack them about as they are as near to mint as anyone could expect and as they are quite rare with the Rosewood finish, they may possibly be quite sought after too, so don't really want to start a hack job, the panels are already damped with bitumous felt pads on every side except the baffle, then a 1" layer of medium density foam then a roll of that white wadding in the top half of the cabinet, that's it, the Rogers boxes of that era used thin wall cabs as their design philosophy, so there is no internal bracing either, flappy walls and flappy bass, they do really need a damn good heavy solid pair of stands. I have actually been thinking of taking a trip to the garden centre, (no stugeek not for some weed) but to look at their range of 12" x 12" square pots, they did some rather attractive granite looking pots last summer, thought I could stand it the wrong way up and place the speakers on the top with Blu-Tak to decouple them, any thoughts, and if they didn;t work I could always use them for growing weed..........^£$*(*)(*)(&%"$%£7-)(^6576£%^" I mean plants, no flowers.............yes !! lovely, pretty flowers :D
    Paul
     
  10. DSJR

    DSJR Between us and them

    The Spendors have no extra wadding at all apart from the bitumen and acoustic foam inside, so Rogers obviously felt it necessary to add a roll in addition to what's there. The bass units do seem to be rather compliant on the suspensions and the crossover does much to appear to decouple the bass unit from the amp, so damping factor (all else being equal) does play a part here I think.

    My suggestion for stands would be something fairly light and rigid, only touching the cabinet base at the edges (RS "clear bumpon style feet" well here). Heavy stands that ProAcs like(d) seemed to make things worse. Heybrook HBS1 stands are a bit high but seemed to work (the top spikes damage cabinets though).

    How long ago was it that you had the LS7's? I wouldn't say their bass was any better from memory...
     
  11. RSC

    RSC pfm Member

    Good advice there... might be worth having a look at what Spendor/Harbeth users use nowadays?

    Paul, YGPM...
     
  12. Pulse Studio

    Pulse Studio TubeTech

    Hi Dave, we do get around us old uns don't we ;)

    I did the cushion mod exactly as you had suggested in your personal mail to me, and believe me it did kill everything, so out they came, at least my back is better now I have them back on me ol armchair.

    I had my LS7t's up until about 4 years ago, sold them on u-pay to a very nice man.
    The bass form them was totally different to the Export Monitors, I could not live with the HF if the truth is known, very lively and quick, the Exports have a slightly warmer upper bass/lower mid compared to the 7t's from memory, again maybe the stands are the main contributing factor here.
    I will try the additional long haired wool tomorrow night and if that don't seal it then I must souce some heavy stands of some kind, maybe just a pile of bricks would let me kkear the difference, that and a bag of builders sand sat on top and my lounge soon becomes a building site, and of course me builders bum :D
    Paul
     
  13. Pulse Studio

    Pulse Studio TubeTech

    After a bit of a break from the toils of tooooooo much bass from these "so called" monitor speakers I decided to try some further experiments today, too cold for swimming in the Thames :D

    So up into the loft to search out a bag of long haired wool, clutching tightly in hand I made my way to the lounge where the speakers have been resting, off came the baffle again and I set about filling the void with the said LHW.

    :eek: :eek: :eek: Shock :eek: Horror :eek: what is this, Oh shit no !!! I know I should have looked before, please don't call me names :( one of my bass units has been wired out of phase to the one in the other cabinet, what the heck, how long has that been like that, I do believe the baffles have been off before judging from the cross head screws that secure it, but surely Rogers could not have possibly let it out of the factory like that ??? could they !!!
    Well the offending wires are now reversed and the baffles back on an secured firmly down, oh my God what a difference, totally, totally awsome, now they sound just like my old LS-7t's but the HF is much better, I am still mad at myself for not thinking to check the wiring in the first instance, but I would not really think it necessary, a true lesson learnt and one happy Export Monitor owner, they do sound really, truly amazing for a late 70's design, well chuffed :)
    Paul
     
  14. RSC

    RSC pfm Member

    Not referring to port noise here, I hope, Paul... :D
     
  15. DSJR

    DSJR Between us and them

    My hearing ain't what it was (although I can clearly hear output from my super-tweets) but drivers out of phase used to give me severe headaches, unless it was 'Briks, where the whole thing is a bit "phasey" anyway.

    Enjoy them.....
     
  16. Pulse Studio

    Pulse Studio TubeTech

    LOL no thank God and it ain't chaffing either :D ooooow sir :)


    David it was only the bass unit of one speaker that was incorrectly wired, the HF and imaging was all still present which is porbably why I had not suspected the phase issue, I think somewhere I did say that I was really impressed with the soundstage, which when you think about it I would have been as the out of phase bass units would have given this all around bloom, it all seems so bloody damn obvious now, but not at the time.

    Enjoy them I certainy am/will my friend ;)

    Have you done what I told you to do yet ?? you know what I refer too :(

    Paul
     
  17. ian r

    ian r 401's Nakman

    Brilliant story Paul brilliant. I have to say though I check that every time with the test cd, large or small systems, I dont trust myself to get it right first time. That weed can also phase one out two!


    Any more to share on phasy briks DS? When I dumped some albums on top of mine this week I was most surprised at the effects. We were moving them from one roo to another and I forgot I'd dome it. Its a new location in the lounge and I havent got them as far back as poss yet due the tight curve already pressing on the wiring up from the crossover below. SO I didnt notice `i was bloccking off the upward firing set! I then plopped more albums on t'other one and listened for a few days.Lots of imaging all of a sudden.

    I wondered about the phasyness - thinking it might be worse than before due to being say 3inches plus from the rear wall. It was easier to achieve in the last location. How much pressure can those leads take? Perhaps L shaped bananas would help, but is that my phasy issue
     
  18. stackowax

    stackowax pfm Member

    "but surely Rogers could not have possibly let it out of the factory like that ??? could they !!!"

    Don't know about Rogers but I once had a brand new pair of Linn Speakers in my house and it was readily apparent that the midrange drivers were wired out of phase. Too bad fixing that problem didn't have the same effect that it did on Paul's Export Monitors--they still sounded dreadful.

    One thing I've always found curious about the BBC monitor speakers I've heard (Spendor SP100, SP1, BC1 & Rogers Studio 1a) is that the louder you play them the tighter the bass gets. Now sure how they do it but its a nice effect.
     
  19. TheDecameron

    TheDecameron Unicorns fart glitter.


    Could it be that the NAIMS with their unremarkable damping factor are unable to control the Exports?:eek:
     
  20. DSJR

    DSJR Between us and them

    Out of phase 'brik drivers..

    It really depends on the room, but the very lively "Concert Room" we had at Studio 99 London totally absorbed the out of phase front mid drivers on some acive 'Biks we had on dem. To be fair, we didn't have many of these odd ones, despite selling at least two pairs of 'briks a week in the heyday.

    Regarding driving these BBC inspired boxes hard, I wouldn't these days, as getting blown bass units fixed will be difficult. BC1's in the early days used to sound as if they were going to shake apart if driven hard.

    Now where is that Erika Badu CD???????????????????:D:D
     

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