HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

They don't look much like Marantz speakers now.

Stu, we can only admire your imagination, when it comes to use of materials in those experiments

antonio66 wrote: ↑Thu Nov 24, 2022 7:10 am They don't look much like Marantz speakers now.

They shrunk a bit and changed shape . I've still got those Marantz cabs, steel lined to within an inch of their lives. Hoping to do something with them eventually. All the drivers went to the scrap yard a month or two back.

Firebug1 wrote: ↑Thu Nov 24, 2022 1:05 pm Stu, we can only admire your imagination, when it comes to use of materials in those experiments

Thanks. Maybe it's an indication that I have too much shite knocking about

Didn't know where to plonk this quote but seeing though i have talked about Green Mountain audio speakers then i put it here. It's all about phase (timing) innit.

Steve Toy - hfs 2015

"Green Mountain speakers. They don't quite have the gravitas of Tannoys but they have coherence to the point of almost eerie lucidity with the right partnering equipment. To me, this is more of significant than tonal neutrality which, although desirable, is not the holy grail for me."

My current speaker set up- really happy with them

Latteman wrote: ↑Fri Dec 30, 2022 2:54 pm My current speaker set up- really happy with them

Interesting shape. Is there some science behind that ? And how do you get adequate bass ? Muller rice ?

I remember hearing something very appealing with my dabbles with OB. None of it was done very well though.

Me, I was just openly baffled about it all

Shape progressed from pure squares to get an asymmetrical baffle- by chance- the Audax / Marsden Hall have a nice deep tone naturally and in this baffle have great bass for my taste & room- if you look closely there is a tweeter on the centre of the grill. The speakers now sit closer to me than any other speaker I’ve had in this room- the sound stage is bang in the middle of the two with great depth, space (air) and musicality. The crossover has taken time to get right I got a pair of doc mod 12” from Ant but these had an annoying ’cone noise’ at certain volumes- not an actual manufacturer fault just what the doping was adding rather than improving, I felt it spoilt what I believe is another very musical driver- this convinced me to move away from the simple cap and resistor and enter the dark art of crossover design- what a headache that is but worth it when u get it right.

Good stuff.

I haven't the time or inclination to try and do a good crossover, no point me even trying. I did consider at one point doing a first order low pass filter for the mid bass as well as the single order high pass on the tweeter but I was going to do it passively at line level like I do with the tweeter high pass.

My experience so far has led to me much preferring the passive high pass filter at line level. It is so easy to do. With my nva amp boards all it requires is one signal coupling cap inserted in series with thd signal before thd first resistor to 0V. For a low pass it would require the value of a capacitor changing on the amp board. You can only really do a first order before running into too much insertion loss and impedance problems. No problem doing a first order high pass when using my 2" wideband drivers as they can handle the slow roll of at 6dB per octave, their resonance frequency is much lower than a 1" dome and they just sound so much more detailed probably due to less distortion down low.

There is a lot of bollox written about active designs. I don't consider a capacitor at line level to be active (no psu required), it is passive in my view. In effect it is the same as active only in the sense that there is only speaker cable between amp board and driver (as long as driver sensitivities are suitable so no padding resistor is required at speaker level. Plus as the filter is before the power amp then the amp only has to amplify a restricted range of frequencies.

I think it is the ideal solution for me. No nasty components between amps and drivers. The tweeter amp is having much less "work" to do because it doesn't have to amplify much of the lower frequencies. That is a big advantage I think. There is still change of phase (timing) but there is no reactive cap (or coil if doing low pass) to play silly games with the driver. Another advantage (theoretical) is that in the case of nva amps with no signal coupling capacitor the whole amp's low pass filter knee frequency doesn't move up and down when you change volume.

Disadvantages- you can't try different speakers at the drop of a hat. You have to pull the amp boards and get the soldering iron out. Only other con that I can think of is that in most cases you are limited to first order. Second order can be done but I don't think I would ever attempt it.

Sorry a bit of a brain dump which could all be bollox. The proof of the pudding is the listening though.

I need to find some new mid bass drivers for this project. The B&W have gone back to the P4's, their original home . Decent mid bass drivers suitable for sealed enclosures are not that common. Most are more suited to bass reflex with qts lower than 0,4. The B&W drivers were not that suitable for closed but I made it work with dope which increases qts and dropping the volume of the enclosure.

I seem to gravitate towards Monacor drivers for some reason. There doesn't seem to be a suitable 6 - 7" with a roll off as smooth as I would like. More searching required.