OK Ive tried the Supravox 215 Field Coil driver on an open baffle system, and the 285 on another OB, so now its time to see if its possible to combine the two to create something even better.
The previous blogs are here :
http://supratekaudio.blogspot.com/2016/10/supravox-215-field-coil-driver-pt1.html
http://supratekaudio.blogspot.com/2016/10/supravox-215-ec-field-coil-driver-pt-2.html
http://supratekaudio.blogspot.com/2016/10/supravox-215-ec-pt-3.html
http://supratekaudio.blogspot.com/2018/08/supravox-open-baffle-high-efficiency.htm
To rehash, high efficiency (HE)gives you dynamics, open baffle (OB) gives you boxless , uncoloured sound.
There are lots of compromises and limitations with HE and OB, but the Supravox drivers are best at minimising them.
So this is what we have.
In the middle the Supravox 215 EXC Field coil driver is still the main star - its run full range without a crossover.
Below it, and filling in the lower midrange and most of the bass is the Supravox 285.
I'm using a MiniDSP digital crossover thats set for 300Hz and does some paraEQ on the subbass.
Amazing good value for sound, and at the bass frequencies does as good a job as my DEQX.
There's no high pass filter on the 285. With OB operation there's an acoustic rolloff with the 215 and although technically not perfect, in real life it works and sounds very good.
Sometimes crossovers do as much damage as they do good.
Supravox recommend a 20mH inductor on the 285 as a first order low pass filter, which I haven't tried yet - I've ordered these
https://www.parts-express.com/erse-super-q-20mh-16-awg-500w-inductor-crossover-coil--266-960
and suspect they might be quite good, although they dont give the option of paraEq for the bass.
The treble horn is from Yamaha's PA range and is the JA-4201 compression driver mounted on an aluminium horn.
The horn is covered in lead sheet and sound-deadening to stop ringing , which is very pronounced untreated.
I wasn't convinced that this was the greatest horn when used as a midrange/treble unit- it was a little ragged in the mids, but used solely as treble it sounds very good- I think that its very important to match efficiencies of the drivers as close as possible, so a horn tweeter is a good choice.
This system is a match of passive and active methodology.
The 215 is used fullrange without a crossover , but being a field coil it does have its own power supply for its electro-magnet.
The 285 is used from 300 Hz down , with the miniDSP digital crossover providing a 48dB cut off and parametric EQ around 50Hz, to counter the open baffles acoustic roll off.
The horn treble simply uses a vintage paper in oil cap for a 6dB first order rolloff at around 2500Hz.
Each driver is connected to its own seperate power amplifier. In this case they are all tube amps , chosen for the specific sound they contribute to the final mix. They all have level controls to adjust the balance between bass, mid and treble drivers.
The preamp is a Supratek, which has very low output impedance and can drive all 3 output channels easily.
I also have the option to use a Dual Cabernet which then gives me the option to connect the bass channel separately , with its own linestage and adjustable output , to easily change bass level, at the preamp.
You may think this system sounds a little "complicated" and complex, but I assure you that it makes fine tuning of the system a very simple and easy, and also very rewarding task.
I've seen people spending months trying to get a three way passive crossover "just right" and never getting there.
This system is very tuneable , and can be quickly adjusted for taste and requirement.
Above all, it is as dynamic as all hell, and throw in the added punch of high efficiency drivers and you get realism that is as real as a punch in the face.
No its not a Magico , its twice as exciting and much more interesting. You can hear EVERYTHING with a Supravox/Supratek/Active-Passive in your house.
Yes they need large panels and the electronics take up a bit of space, but its the price you pay, and what a result.
So how does this 215/285/4201 version compare to the 215/Eminence15"/RAAL version?
I prefer the 215 with the Eminence bass drivers. Just. Its a matter of subjectiveness , they're different , but one's not necessarily better. The 285 is gruntier, has a more forceful punchier bass, that is just a little too much sometimes. It doesn't quite have the naturally defined and acoustic tone of the two 15" drivers, which is what you would expect - one 10" driver v two 15" .
The 4201 horn is very exciting , and without being too obvious, lets you hear all the detail. The RAAL might be a little less exciting , but delivers the same detail, and perhaps is a little more subtle and natural sounding.
I do think the 285 and the 4201 together make an excellent two way HE system- its punchy , has a huge soundstage , delivers big time. Needs little power to make a big sound, and you will never get tired of it, something that the Lowther/Fostek/Tannoy HE speakers seem to be guilty of.
Like the Supratek preamps, the Supravox drivers are not cheap, but neither are they expensive for the performance they deliver, and may be best value you can get, perhaps even at any price.
EDIT.
Supravox recommend the 285GMF be used with low power amps, and it certainly seems very happy with a 300B Single Ended tube amp. Its a little less grunty , and follows the bass line more easily , with better definition with a low power amp than with a SS amp, which seemed to overpower it, which is interesting, and pleasing.
I'm going to see if I can get hold of a 215RTF to go with the 285GMF and the 4201 horn- I think that with an all tube system, it might be something special.
285GMF
