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Ming,

I was thinking about this SG146LD4 driver again. They say: 106 dB/ 20 - 500 Hz, 19,000. Well, let look at this a little bit further as I feel that might be very interesting driver.

I admit I never heard about this driver. All that I know about Got was from here: http://www.eifl.co.jp/index/goto/goto.htm, where the SG146LD4 driver was never mentioned.

So, the SG146LD4 is driver that GOTO clime might work down to 20Hz. I think they slightly fool of it and it is … very good. Considering the side of the driver and a few other things I presume that it might be a 40-60Hz driver with reasonable primary resonance of ~50Hz -60Hz, or even twice higher. Making the climes that this is 20hz driver was foolish for GOTO as then turned off many perspective customers that might find this driver worth of their interest. GOTO did not lie; you can push 20Hz out of this driver. The driver looks like has 4” throat and if someone decided to run fill 20Hz mouth from 4”  then it will have tremendous horn equalization, I would say it will have +12dB -18dB at bottom, or perhaps even more. Sure it will be 50-70 feet long but it is not my main point. My main point is that 20Hz application of this driver is not something that should be advertised. Such 70 feet 20H horn will have a super high throat reactance and I down that the driver is optimized for that duty.

I intentionally write it while you are in Japan visiting your GOTO folks because they need might like to review what they say about the driver and some other things. If I were a perspective customer then the very first question I would ask myself if the driver might be optimized for MY GIVEN HORN. A MF drive might be with fixed compression ratio and fixed back chamber as using it in 1000Hz horns or 700Hz horn make lilt difference. However, with midbass driver is very different story – in such a driver the volume of back chamber is the key for proper driver to horn interface. The GOTO folks if they are intend to sell those drivers to horn people who have brain, experience and ears (me for instance) shell make the back changer of that driver adjustable or tunable with publishing the available open air resonance frequency for max and min chamber.

If GOTO folks with I can pitch a few ides how it might be done with “back chamber bleeders”. I think, what you are there you might talk to them about it. I well understand what GOTO is trying tom do – thy try to use fixed back chamber and to deal with throat resonance by multiplying drivers. I can give many reasons why it is wrong direction in attempt to match driver to horn.

So, what I would like to see is GOTO converting SG146LD4 driver into the SG146LD4 with variable cone damping. You, as a distributor will be benefited as well as it would make the SG146LD4 more attractive for perspective users.

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