Passive sub build

[manisandher]

I've just received 4x passive subs built by KJF Audio:



The specs for each sub are as follows:

- 91L sealed enclosure
- 1x 12" SB driver (19Hz fs)
- no crossovers
- low-passed 36dB/octave @ 70Hz using DSP
- 25mm MDF
- beautifully built and veneer finished
- 37Kg

Here's how they look alongside my horns:



They work exactly as I had hoped. The upper-bass horn is band-passed 70Hz to 500Hz, relieving it of doing any heavy lifting low down, resulting in a nice uptake in mid-bass performance (to my ears at least - not taken any extensive measurements yet).

A massive shout out to Stefan @KJF Audio. Top man. Absolute pleasure to do business with. (He also builds great Hypex-based amps .)

Feel free to ask any questions should you have any.

Mani.

 

[Psilonaught]

Nice setup there. I still have a desire to listen to a properly sorted horn system.

What DSP approach are you talking? Hopefully not anything using AD/DA given how transparent those speakers look.

 

[manisandher]

Nice setup there.

Thanks.

I still have a desire to listen to a properly sorted horn system.

Horns definitely have their challenges, but set up well, they have a visceral impact that live instruments/voices have and that direct radiators don't seem to be able to recreate easily... that's how I hear it, anyway. But of course, I've only heard a few dozen DRs in my time . And most of the horn systems I've heard over at Munich and elsewhere have sounded pretty underwhelming too. I've had to work really hard to get my horns to where they are now - a sound I could (and will!) live with for the rest of my days .

What DSP approach are you talking? Hopefully not anything using AD/DA given how transparent those speakers look.

No, no AD/DA. I've previously outlined my approach to DSP/crossovers here: https://******************.com/foru...ctive-crossover-using-roon.29882/post-1046848. I've found that having the ability to time-align all the drivers is absolutely critical - small differences in time alignment seem to make vastly more difference than small differences in levels between the drivers. Again, to my ears.

But as an aside, I'm not sure AD/DA is necessarily bad. I use my RME ADI-2 for headphone listening and controlling volume after the phono stage in my vinyl system. The RME has beaten every analogue preamp I've compared it to... to my ears at least. But again, I've only tried a handful of preamps that I've had access to over the years. FWIW, the closest to the RME has been the Audio Synthesis balanced passive (let down by a drop in dynamics), followed by the Pass X1 (let down by a drop in transparency).

Mani.

 

[Psilonaught]

Thanks.


Horns definitely have their challenges, but set up well, they have a visceral impact that live instruments/voices have and that direct radiators don't seem to be able to recreate easily... that's how I hear it, anyway. But of course, I've only heard a few dozen DRs in my time . And most of the horn systems I've heard over at Munich and elsewhere have sounded pretty underwhelming too. I've had to work really hard to get my horns to where they are now - a sound I could (and will!) live with for the rest of my days .



No, no AD/DA. I've previously outlined my approach to DSP/crossovers here: https://******************.com/foru...ctive-crossover-using-roon.29882/post-1046848. I've found that having the ability to time-align all the drivers is absolutely critical - small differences in time alignment seem to make vastly more difference than small differences in levels between the drivers. Again, to my ears.

But as an aside, I'm not sure AD/DA is necessarily bad. I use my RME ADI-2 for headphone listening and controlling volume after the phono stage in my vinyl system. The RME has beaten every analogue preamp I've compared it to... to my ears at least. But again, I've only tried a handful of preamps that I've had access to over the years. FWIW, the closest to the RME has been the Audio Synthesis balanced passive (let down by a drop in dynamics), followed by the Pass X1 (let down by a drop in transparency).

Mani.

Very glad that you are setting crossover points through Roon rather than using a DSP digital active crossover.

In my experience, through careful listening, even very high quality digital crossovers leave a digital edge that a good and transparent system will pick up. That is my experience through various trials including with a Monacor unit

I personally only have a 2-way active setup so not as complex as yours. For me, the sublime audio K231 with fixed, card based crossover points, was an absolute revelation, both in transparency and non-existent noise floor.

I apply my EQ adjustment through my Aries G2.

Interesting multi-channel dac you are using by the way, not familiar with that unit. Have you considered the okto 8 dac?

 

[manisandher]

Interesting multi-channel dac you are using by the way, not familiar with that unit. Have you considered the okto 8 dac?

Haha... I've just added my signature .

But it doesn't seem to be coming out right. Anyway, here it is:

Main: Okto dac8PRO -> 6x Neurochrome 286 mono amps -> Tune Audio Anima horns + 2x Rotel RB-1590 amps -> 4 subs
Office: MOTU UltraLite-mk5 -> 6x Neurochrome 286 mono amps -> Impulse H2 speakers
Vinyl: Technics SP10 / London (Decca) Reference -> Trafomatic Luna -> RME ADI-2 Pro

Mani.

 

[Psilonaught]

Haha... I've just added my signature .

But it doesn't seem to be coming out right. Anyway, here it is:

Main: Okto dac8PRO -> 6x Neurochrome 286 mono amps -> Tune Audio Anima horns + 2x Rotel RB-1590 amps -> 4 subs
Office: MOTU UltraLite-mk5 -> 6x Neurochrome 286 mono amps -> Impulse H2 speakers
Vinyl: Technics SP10 / London (Decca) Reference -> Trafomatic Luna -> RME ADI-2 Pro

Mani.

Great minds

 

[Psilonaught]

What is the power rating of your tweeters and mid-bass horn sections by the way? Just curious why you are not using something glass on the top end?

 

[manisandher]

What is the power rating of your tweeters and mid-bass horn sections by the way? Just curious why you are not using something glass on the top end?

The tweeters? 100W continuous.

Before going fully active, I used to drive the mid- & high-horns with Thoress 300B monos. The sound was nice enough... though (I now realise) quite flat and unexciting.

I didn't even bother trying the 300Bs again once I went active. As soon as I heard the Neurochromes I was sold. Really, really nice-sounding and DEAD quiet - put your ear next to the mouth of the 107dB/W@1m high-horn and you'll hear just the faintest of hiss coming through.

And being able to get the sound I want with 5x totally cool-running amps per channel is a god-send .

Mani.

 

[manisandher]

In my experience, through careful listening, even very high quality digital crossovers leave a digital edge that a good and transparent system will pick up. That is my experience through various trials including with a Monacor unit

Yes, I tried digital crossover a while ago - [Edit: it was a DEQX unit from about 10 years ago]. Hated it. Went with a pair of Pass XVR1 analogue units instead, which were quite good. But as I mentioned earlier, I'm now convinced that time-alignment is a must, especially for my upper-bass horn, which fires downwards and just sounds wrong without time alignment.

If I wasn't doing DSP in software, I'd probably have looked into DEQX again (and perhaps Monacor) just to see if the SQ had improved any.

 

[Psilonaught]

cool-running amps per channel is a god-send .

Mani.

Fair enough. You would hate my tweeter/ mid bass amps

 

[manisandher]

Atma-Sphere monos? In any event, I'm sure they sound superb.

I need 10 channels of amplification for my main system and 6 for my office. Valves and class-A SS are therefore out. Yes, I could contemplate valves for the high-horns in my main system, but I'm not sure what problem I'd be solving by going that route.

I don't for a second want to give the impression that I have everything perfectly sorted. Over the years I've come to the realisation that audio is all about compromises and trade-offs. I the ones I've made seem to work pretty well... to my ears at least.

I'm hoping Stefan @orangeart (KJF Audio) will come over to take a listen at some point. Will be interesting to hear his thoughts.

Mani.

 

[Psilonaught]

Valves can be very problematic - I've had issues with both my main sets of valve monos involving trips to engineers, so last night was my first session in two weeks.

I would love to find a solid state amp that gives me the same rich textures as a good triode amp! I might try one of Ralph's new ganfet amps at some point!

Congrats of a very sorted and visually appealing (important!) setup!

 

[manisandher]

For me, the sublime audio K231 with fixed, card based crossover points, was an absolute revelation, both in transparency and non-existent noise floor.

I'd never heard of Sublime Acoustic before. That active crossover looks superb... at a great price!

 

[Psilonaught]

I'd never heard of Sublime Acoustic before. That active crossover looks superb... at a great price!

It pissed all over the Monacor DSM unit it replaced. Zero hiss, better information retrieval and completely neutral. You can chain two together to give you 4-5 way.

The specs are insane;

THD Better than 0.0005%
THD+N: Better than 0.0028%
IMD : Better than 0.0058%
SNR: 120dB

 

[manisandher]

It pissed all over the Monacor DSM unit it replaced. Zero hiss, better information retrieval and completely neutral.

If you can physically time-align all the drivers, I can imagine that the Sublime would be a great active crossover solution.

In my case, the upper-bass horn is about 1.5m in length, with the driver sitting towards the top and firing downwards. So I need to delay the sub, mid and high drivers by about 5ms in order to time-align with the upper-bass driver. Only really achievable using DSP, AFAIK.

Implementing all the necessary DSP in Roon and feeding to a multichannel DAC is actually pretty straightforward and works incredibly well. I can imagine this helps reduce harmonic and IM distortion, as each driver has its own separate DAC and amp acting across a narrow bandwidth.

I'm certainly very happy with the result I'm getting.

 

[manisandher]

THD+N: Better than 0.0028%

Okto dac8PRO THD+N: 0.00012%

 

[Psilonaught]

Nothing wrong with DSP if you are doing it upstream, like in Roon or like I do in my streamer. It is the AD/DA process that I have an issue with.