RD-75 clone?

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studley

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RD-75 clone?
« on: 26 Nov 2018, 12:22 am »
Danny
Having successfully cloned the Neo 3, I have a suggestion for you.  There  are a LOT of DIYers who would love to be able to get hold of RD-75 ribbons ( have a search on DIYA if you doubt it) and so I was wondering whether you have thought about the possibility of cloning them?   I can confidently predict that you would sell a lot of them . . . .

Danny Richie

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Re: RD-75 clone?
« Reply #1 on: 26 Nov 2018, 03:19 am »
Danny
Having successfully cloned the Neo 3, I have a suggestion for you.  There  are a LOT of DIYers who would love to be able to get hold of RD-75 ribbons ( have a search on DIYA if you doubt it) and so I was wondering whether you have thought about the possibility of cloning them?   I can confidently predict that you would sell a lot of them . . . .

That is interesting. I had a tough time finding a good use for them myself. Sensitivity was rather low and they lacked the real dynamics and clarity of the Neo's. The top end was also rolled off pretty hard too. So they lost some of the upper spacial cues. And they didn't play down low enough to catch all of the mid-range (playing down to 200Hz). 300Hz was about the extent of their range, so it dropped the lower vocal and then that range had to be split with a different driver.

And the the sensitivity so low it was hard to find a line of any woofers to match them. In the LS-6 and LS-9 line sources the tweeter line hit just over 91db. To match that I had to design a 3 ohm woofer that was 83 to 84db sensitivity.  The RD-75 hit only 85db with 1 watt. So a line of woofers to match it would have to be in the 78db range.

HT cOz

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Re: RD-75 clone?
« Reply #2 on: 26 Nov 2018, 06:14 am »
That is interesting. I had a tough time finding a good use for them myself. Sensitivity was rather low and they lacked the real dynamics and clarity of the Neo's. The top end was also rolled off pretty hard too. So they lost some of the upper spacial cues. And they didn't play down low enough to catch all of the mid-range (playing down to 200Hz). 300Hz was about the extent of their range, so it dropped the lower vocal and then that range had to be split with a different driver.

And the the sensitivity so low it was hard to find a line of any woofers to match them. In the LS-6 and LS-9 line sources the tweeter line hit just over 91db. To match that I had to design a 3 ohm woofer that was 83 to 84db sensitivity.  The RD-75 hit only 85db with 1 watt. So a line of woofers to match it would have to be in the 78db range.

But Danny they look so cool!   :lol:

studley

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Re: RD-75 clone?
« Reply #3 on: 26 Nov 2018, 10:26 am »
There’s a long thread on DIYA started by StigErik.  It documents his OB journey over about 6 years in which he tried lots of different drivers and approaches.  He stopped experimenting after he acquired a pair of RD75s.  He runs them from about 200hz all the way up.  Below 200hz he has I think 4 humongous H frame woofer stacks, each one using multiple 21” woofers.   He does however use DSP.   

Danny Richie

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Re: RD-75 clone?
« Reply #4 on: 26 Nov 2018, 02:27 pm »
There’s a long thread on DIYA started by StigErik.  It documents his OB journey over about 6 years in which he tried lots of different drivers and approaches.  He stopped experimenting after he acquired a pair of RD75s.  He runs them from about 200hz all the way up.  Below 200hz he has I think 4 humongous H frame woofer stacks, each one using multiple 21” woofers.   He does however use DSP.

You can correct a lot with the DSP system, and make them work. I would not however want too many of those DSP system in my signal path. Rich Hollis has the only high quality system that I know of. So his system would make it work and sound pretty good.