What are these ribbon drivers?

I came across someone selling these speakers locally and I have no idea what they are. Does anyone recognize them? I'm not sure if they're a DIY effort or an older production driver. Pictures aren't great because he didn't have a light on and it was hard to get a good picture without light.

Here's the whole speakers (in two parts):

RFvIJS45FyHX1W5d6W_mXlYv6emCeLuHr3nFQwt-F_nbV7BFkgQTTALoVI8cGfv_4QGa8p4krAat2MsNH_cNkGD7mE56-i_NDO_DeflhKcWMyZ2pER63CbaWMTetGYl9ibizjLj3nNFaydYe_IK5B2lpyIYl-fV1zPQ_7IvScaQazVusl9avyc8LYwU2vSG41El-M1ElW5trFT0k0r8rZk1iFnBYsFXwrFyaOibX9_bjtKcfZ_atkx4mQ-LBf0QywkFudRPDMN9fOlNiUvwBmoD_xqa8jHm5EMoqsY9kyn3jR_WliVVUxAiX9jO2xK1lrZcE_JZGFD5OwA9NRUPNkYJslgrrFi2SoLqt9OkKd1bUydyqwMgkxbi4P1NVy6Uq3MIsv07TaZ3qqqc_z5aUUXgzipDS5Yx2NDejiwlT7sbmsTjizPYdADxwf0vpBWkBgomigCI-s5DlAT5apef-Wh-ZFNGn3qT7vxn0YZMC2yUDNavqY0gFDNwFjiLVfXdDQC56CITFuXKhdrDm7BJgBtjIbjw5ahEcxYDMMMDA_Ig8FLsqmgFGvYB48Ju3IBospjQC=w598-h1063-no


close-up of tweeter:

3UwYT7TMEpay_Jn2Wsc4NJPsgYACE29ZwngFXLCG-OqRx9V7HXDbNBdQpvCaxheuZFielfeRWHPymH7piuFFy7SQVeFcpYfk3Dus61MKF2ipwvaWuC-pWQ-TRJDZI_-b8deYegGlaGbxKB9dmUkt8wAw1OPhEGyz9UMVtFgM17VIt0IWUgjV7Tfi2XcGGIq8AqoZISDSIm9xmiTXYLvH4H6TUd9xESovh7D9bvtUzR3hwDLN2qOIXkkqBnLel4cAzd6cWGp8K6hMRyvnIrhW1MJNry8q8qxnOZZP_cu72tUgZ_ZB5inqZKXinfFoAW-srqpfpxy-v1o6hl14IG2dY2doz9l4Z_iLSoDnLHVTNSdW2JNzudIdFSk7WAJxFpBQsYF_Lg3kzijG0EXUJJvpsX0HBZN1-Iyjpuy0hlOVI9NZmh6wfvA2CtQ2FqxhP8mWZghBxJO41gAAa1Wv1zdDVKRi7j6g_IDXqAhAofXqkUEUFVnwTfuznJ3F_kRM-jyoofWgvFaekHTQgyQVCXYQNY29FJjP4W2fG5WCgpd9ep25_GVjU0lXX6xP7OsLLUqRW9YY=w598-h1063-no


another view of front of tweeter:

ny0nIpmq1IKQbcscGwaJSlW1aP0CiAzSE_2QFdhriE9krDDxbDt-dttqJJ5a_bYvpXbGCfDX3IC6xNDFA6T7uxzwVHDZbvXHdVxzQ4YD2YYTuarj-Mpuufz-8GpRsNPKHgZTH1juI11QBJCHLnoYWcGrNNoz8g7E307gTsPMFyH3hRIb--tM1VN7sIqUJUX5JJMlfjuRXAaIkMTHf2QVVhZOFimSMfH1VeaE1enx5yyy7X-HV72NwtJGyIIIaSqp40Mj9nutKgcr4tzJbFpy49pz5tHmlOFiiv7p3WDzSKNnJd18z24nTtUiPcvw9XKwtTefkwqeOkj43Yp0FRy6yRhhWU4_PqP_iTyWuhE6mh2GvrGlaXJAQnk1Aj3Lzi6MwRp8Xc8n888bL-UgcLCiSS6z4vpup9VDDryXA5Mp9sBhcaVanwDTyRM2FOfjZkr4QCpcVBD-ibwzTjWlr_cn7fMy9R6DXcMrpqEpUa-FGJd-V5VTJGYHApfF-zNCSSKGBWXPBg6SVrdZUfk-X-VTDJHoevMeWK88d4yL65UfbSF1og8jV4Q_yAwrITB1SxKl1rv7=w598-h1063-no


back of driver:

I0_wDVerRhgBDOxMXvWoHfv8GaqRSzS7GKkwES4Qbz7nn-H_EkTbXrtAH0kPVx4Ui_sGCyqehxZC6upqfyNWh0aq0Z01I0w2EzVRlkKwaHisaRiXKnNbTK73taFxfhdzOvMD7d0J416StFVfVBoCTFgWBCNgejRY15Z2RQfmkQsmCGKxe6Djemn_HGPl5tXJrEq-KtEz8mwe-3i63kkqy7pW_mHfK0NbdruQHGRINQyknI0wIRpWsEJbhFmaUyKzGED901wpXn13f8VHolkHiFnkgBiYK6hEJ8cD_lcre83bYpNhNjQi4-EaLkmvfpPwKZhIqQn3HI5fHcIh3-f_P08F17aEjeuDun3xhGF55NScxRpXLL2olUvm8wjO9pKf0703655ieADf7-55iUV6RBdTDCpD-yqODhpdyQl_VJOAyEDKDC5Uf6-VprFZSFmEe7snkeqbcbpl6cQ2v06bsiuP90utWRJUcrnwhAxNU-56ktEM7hRqOHjFEpQ4ZpPZf5I4-UdLstBgryaH2lu9u66Xj7cPTJnxFWRbOry_vnXhd8wnWBIzYCDelFb24Ee_B_jF=w598-h1063-no


The tweeters are 23"x5" overall and there are two a side. The Boston Acoustics drivers were added later, the white/clear cone drivers were what came in the speakers. Does anyone recognize these or are they a really nice DIY speaker?
 
The name of the ribbon unit in your loudspeaker.

Strathearn developed/made it, used it in their own loudspeaker, also manufactured them for other audio companies.
Arnold Nudell used the unit in his late '70s Infinity loudspeaker model, renamed the Strathearn model to EMIRM.


(MRHF is short for mid-range/high-frequency)
 

Attachments

  • Infinity-QRS.jpg
    Infinity-QRS.jpg
    62.3 KB · Views: 552
Could be.

The EMIT was a further development by Mr Christie, original design was by Mr. Von Recklinghausen.
Both MRHF and EMIM are not true ribbons, but planar magnetostatic.
Very likely that Mr. Christie also used the MRHF driver as a start, to develop the EMIM.

(also a fair chance that it was born of logistic necessity after the Dublin drama of the late '70s (what other way is there for the Irish but dramatic)
 

lowmass

Member
2016-01-26 12:46 am
I have a bit of experience with the Stratherns and even have replaced the diaphragms on a few pr. They are capable of very good performance when used properly. Easily competing with modern planer magnetics. In stock trim they use some very low density fiber board as damping material for the tensioned film diaphragm and the perforated aluminum on the back sides holds some fiberglass in place to give some further diaphragm loading. Check to be sure the magnets are all in place and none broken loose. the build is quite fragile so be carful poking around. Very good plainer sound from about 400hz on up to approx 18khz. they have a couple bumps in freq response cant remember where exactly but its up around 5-10 khz. Typical dual slot planer peaks I believe. Many people used a trap circuit or two to tame. Early units had slightly thinner foil traces than the latter units but not a significant perf difference. Make sure they come with the transformers. If in good condition you would pay easily 500 pr or more for a modern driver to compete.
 
thanks lowmass.

they appear to be in excellent shape actually. I hooked them up straight (through an electronic crossover at around 300hz) and they sound very very good. they're missing a tiny but on the highs, but not much. they are pretty directional, but sound good.

they did NOT come with transformers. there's a 2 ohm resistor wired in series between the two panels on each side, making for a ~3 ohm load. I paid $200 for all 4 plus a few other drivers, so it was a great deal.
 

lowmass

Member
2016-01-26 12:46 am
well you got a great deal IMO. I used to run them straight too. I think I still have a pr of the transfomers somewhere. I made a foil resistor out of kitchen foil Ha.

Done right these drivers can run with any new planer mag IMO.

Back in the day I experamented with changing the mass and damp of these. Stock foil was around 6 micron and the film was about same or just a hair thicker. I tryed a few diff thicknesses of foil and film. Believe it or not I liked the heavyer stuff better BUT in the end its largly how you taylor the overall freq response. Still the heavyer stuff, probly about 12 micron sounded best to me. A bit more dynamic. Many complane about the highs. They do roll off above maybe 15k. Some went to extra tweeters to compensate. I never really liked that sound as good.

The best mods are to remove all the fiber board dampers and attach 1/4 ich thick 2 lb density polyurathane foam to them and reinstall with a light compression. This terminates the diaphragm a bit better and allows you to get rid of the fiberglass and aluminum screens out back. They seemed a bit more natural with this mod but its subtle. Then just use some trap circuits to tame peaks. You end up with about +-1 db all out. Very smooth strings.
Full line is always best and if you can get 1 more par you will have a reference quality system that can go to about 150 hz with wide baffle.
 
I have 2 pair of the coffin shaped cabinets. I stacked them and used 4 15 inch bass drivers 2 per cabinet and 4 8 inch mid bass drivers 2 per cabinet in a trit amped system sound was great but system was huge.
Wife gave the bass units away but I still have the 8 statherns. I stopped using them when a got a pair of Reference 3A Supremea most will have never heard of these they are the Reference 3A with a ported bass cabinet as stands. The low and mid bass was better then the tramped system and a lot smaller. I have been thinking running them dipole with the 3A Supremea used for bass and mid bass. I would like to make the cabinets for them as small as possible. What would be the minium width of the baffle need to be if I use them from 500 up.
Thanks
Lonnie
 
Hi Lonnie, do you have the Strathearns?

I have 2 pair of the coffin shaped cabinets. I stacked them and used 4 15 inch bass drivers 2 per cabinet and 4 8 inch mid bass drivers 2 per cabinet in a trit amped system sound was great but system was huge.
Wife gave the bass units away but I still have the 8 statherns. I stopped using them when a got a pair of Reference 3A Supremea most will have never heard of these they are the Reference 3A with a ported bass cabinet as stands. The low and mid bass was better then the tramped system and a lot smaller. I have been thinking running them dipole with the 3A Supremea used for bass and mid bass. I would like to make the cabinets for them as small as possible. What would be the minium width of the baffle need to be if I use them from 500 up.
Thanks
Lonnie