HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

Yes don't do it.

Feck - that was an epic read- 2 days on /off

And its not even finished yet.

You should try reading the 2200 page marantz cdp modification thread on diyaudio. I have got half way through but need a rest for a while.

My friend is doing that

Thoughts turn back to my speakers. The more i think about it the more i think Doc's version with 12 inchers is the way to go for several reasons.
1) The bass drivers are upfiring so in phase with the ground
2) Mid driver is side firing so still not pointed directly at you
3) With my isobaric implementation it is a much better use of space. I can give each driver a cube to work in and the cabinets will not get too deep, only taller.No stands needed.

Thinking of trying a third 12 incher to make three in total. Only thing is that Richard is no longer here to do the doping. So i am on my own with that one. I have enough bison kit and platidip and can copy the amount that is on the ones i have. I'm sure Richard would approve and would be egging me on.

I have a pair of diy BBCs too- the 12” up firing but decided to fire the tweeter & midrange forward- to each side of my speaker placement is glass- window one side & ‘French doors’ on the other - I was worried this may adversely affect room acoustics- but it’s an itch I know I will have to scratch and try the Doc configuration too.

Now is the perfect time to try and dope drivers yourself in honour of doc modding.

Just remember bison in the centre near the dust cap and plasti dip all over. The amounts are personal preference.

Anybody who builds speakers owes to themselves to hear the doc way

If my watching is anything to go by, don't just 'splalm' the bison all over the cone, but do it in layers starting around the edge of the dust cap.. before spraying the whole with Plastidip. Tom may hopefully confirm and expand on that, as he's seen and is able to do the job first hand I gather.

Glass can be horrible for room acoustics if there's too much of it. It 'rings' right where our ears can be very sensitive, so having the mid drivers facing you or facing inwards isn't necessarily a bad thing to try. Whatever suits your 'way' with the music - no hard and fast rules really, just go with your gut feelings and try to keep live and other 'HiFi speaker' sounds as a kind of reference for 'steering' your builds.

One thing to bare in mind. Heavy doping destroys efficiency (twelve ohms inline on the tweeter pad must tell you something - the tweet isn't a high efficiency compression driver either). It's all a balance of compromise.

The resistor on the tweeter is dependant. I use expensivec scans peak tweeters with a 5 ohmn resistor..

Doping increases the effeciency it deos not destroy it. There is an argument to say its the same as a passive xover

Thanks for the doping tips. I have some experience doing it but with continuous cones with no dust cap. I did that in thin layers but it did not work out. Aluminum continuous cones are not for doping.

I have enough confidence to do it and know which drivers to use. The doc held his dopi g se rets close to his chest and rightly so. However, any input from those in the know would be much appreciated (by PM if necessary).

Stu