Alternative HF Ribbon Tweeters
I was sent the following reference info from a friend. Hope it helps!
The MHT12 should be a close drop-in for the RHT12, but is very expensive.
An alternative, if you can handle the mechanical changes to the tweeter mounting, would be the HiVi RT1C-A.
HiVi RT1C-A Planar Isodynamic Tweeter
It has a slightly lower DCR and a slightly higher sensitivity.
Adding a 2.2 Ohm series resistor to bring the impedance up should fix the excessive sensitivity too (end result 7.7 Ohm/91dB just as the original tweeter).
You could put a 3.3uF cap in parallel with the 2.2 Ohm Resistor to bring the extreme high-frequencies up a little.
I was sent the following reference info from a friend. Hope it helps!
The MHT12 should be a close drop-in for the RHT12, but is very expensive.
An alternative, if you can handle the mechanical changes to the tweeter mounting, would be the HiVi RT1C-A.
HiVi RT1C-A Planar Isodynamic Tweeter
It has a slightly lower DCR and a slightly higher sensitivity.
Adding a 2.2 Ohm series resistor to bring the impedance up should fix the excessive sensitivity too (end result 7.7 Ohm/91dB just as the original tweeter).
You could put a 3.3uF cap in parallel with the 2.2 Ohm Resistor to bring the extreme high-frequencies up a little.
I have replaced the RHT12 s with the MHT12.
But there are some unnoticeable changes on the sound, but i do not mind.
I have concerns about changing the PR170MO with the first one i had PR17HR702CA7-8 so i can fix the frequency of 4000-5500 khz. I'm currently using an active cross over.
There are spare parts on the market.
But there are some unnoticeable changes on the sound, but i do not mind.
I have concerns about changing the PR170MO with the first one i had PR17HR702CA7-8 so i can fix the frequency of 4000-5500 khz. I'm currently using an active cross over.
There are spare parts on the market.
Lucky me!
I have sourced a pair of SD1 in light oak, and they are a lovely match with my OBS. My other SD1 are black ash. It was interesting to compare and contrast. The RHT12 tweeters have the waveguides fitted (and are mounted upside-down in the cabinet). Other than that, they are the same as my black pair.
The bass and mid drivers are per the parts numbers listed above. They are rather heavy, with quality cast baskets. The cones are both doped, the dust caps are perfect, but they all need re-foaming. Any links to reputable UK/EU suppliers gratefully received! The bass and mids all have a RC filter directly at the terminals.
Mid 10R 7W / 4.7uF 50v axial bipolar Bennic
Bass 10R 7W / 16uF 50v axial bipolar Bennic
Re-foaming looks quite straightforward.
Cheers
Jon
I have sourced a pair of SD1 in light oak, and they are a lovely match with my OBS. My other SD1 are black ash. It was interesting to compare and contrast. The RHT12 tweeters have the waveguides fitted (and are mounted upside-down in the cabinet). Other than that, they are the same as my black pair.
The bass and mid drivers are per the parts numbers listed above. They are rather heavy, with quality cast baskets. The cones are both doped, the dust caps are perfect, but they all need re-foaming. Any links to reputable UK/EU suppliers gratefully received! The bass and mids all have a RC filter directly at the terminals.
Mid 10R 7W / 4.7uF 50v axial bipolar Bennic
Bass 10R 7W / 16uF 50v axial bipolar Bennic
Re-foaming looks quite straightforward.
Cheers
Jon
need SD OBS xover info
hello Jon,
I was hoping you can help me out with regards to my SD OBS , mine are the Mk-2 with the - ribbon tweeters - .
Purchased recently, some previous owner has made a DIY crossover that makes no sense ,
its basically just 1 cap on the tweeter
2 caps + 1 resistor ( in series ) to the mid
nothing at all on the bass
see photo attached.
do your OBS have the original xover? if so a photo of it and/or circuit diagram would really help me out
(. I do not understand what this DIY xover on my speakers, as the mid has the terminal going to 2 caps in parallel ( 112uF + 14uF ) > connected to a 4.7 resistor, THEN connected to driver terminal
this isnt even a correct low pass filter (?) .
hello Jon,
I was hoping you can help me out with regards to my SD OBS , mine are the Mk-2 with the - ribbon tweeters - .
Purchased recently, some previous owner has made a DIY crossover that makes no sense ,
its basically just 1 cap on the tweeter
2 caps + 1 resistor ( in series ) to the mid
nothing at all on the bass
see photo attached.
do your OBS have the original xover? if so a photo of it and/or circuit diagram would really help me out
(. I do not understand what this DIY xover on my speakers, as the mid has the terminal going to 2 caps in parallel ( 112uF + 14uF ) > connected to a 4.7 resistor, THEN connected to driver terminal
this isnt even a correct low pass filter (?) .
Attachments
This is great , v helpful......... I know this an old thread now , but what is the ' missing bass take off ' ?
I,e. Is that a missing component from the circuit diagram?
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Hi. Once again sorry for not being here very often. Where I have marked "bass take-off" is where the + wire to the woofer should be attached. There are no components which are not visible in the diagram, only those words.
Hi everyone,
Glad to see Steen's designs are still around.
The Visaton tweeter in the SD1 is definitely the MHT12 (it's the most expensive ribbon tweeter in Visaton's catalogue.
The OBS carried the RHT12 I think but not too sure.
My dad used the SD3 which weren't bad either, I used the SD1 as a reference demo speaker in my company, the OBS occasionally too.
The Swiss distributor even used the SD1 for the Basle Hi-Fi show back in 1986 or thereabouts with excellent results for demoing Jadis amps.
And Steen wouldn't be Steen if he wasn't going out of his way to help a customer with one of his babies. (Too bad for his lovely wife though)
I'm currently running a set of Wharfedale EVO4's and you can see quite a bit of resemblances between both designs.
The SD1 were way ahead though, probably still are. Excellent value for money.
When replacing either the midrange or woofers make sure you use the exact same model and check the specs, they sometimes change.
Also, both mid and woofer were treated with a coat of butyl made by Dunlop IIRC.
Cheers, 😉