Top subs (velodyne, Revel etc)- Transparent enough for the purist?

Hi

There has been a lot of positive feedback in recent years about how great the top subs are- you know, the DD velodynes and Revels of this world, ones which utilise microphones or SLMs and eq software to provide a flattish overall response and controlled deep bass, often rolling off the main speakers slightly in the process.

Even some with purist vinyl/valve systems have sang the praises of these subs stating that their benefits outweigh the risks of putting the delicate audio signal through a digital filter.

But just how transparent are the high-pass filters in these subs? And surely the use of long cables (even at line level), quite possibly many metres long if a sub is in the corner, must have a sonic penalty?

Other folks say that they prefer to keep the signal digital filter-free by using subs at high (speaker) level or by using a second output off a preamp.

My own system could be described as reasonably purist (for want of a better term) in that it utilises a MFA passive pre and silver-wired 300b push-pull amp into large Tannoys. I would be very interested to hear opinions on this matter, especially from those with similar systems to my own.

 

Wow!

I have a customer who has a very very similar set up. I just sold him a pair of Glenairs to go with his huxly scientific intergrated. He still has his MFA. I sold him a couple of SPJ turntables as well.

But to get to the point. He uses an old Rel sub with his system.

SPJ Laluce
SPJ Ebony cartridge
MFA pre
Huxly Scientific SE triode intergrated
Tannoy Glenairs
EAR phono
and an old REL Sub

Sounds quite nice. It certainly adds in a positive way to the over all sound.

 

Lets Active

Hi Baudrillard

This subject is of current interest to me. I have been reading recently about the advantages of active crossovers with active speakers (see articles on TNT Audio and Elliott Sound amongst others) and it is absolutely clear that such active systems are inherently superior to the passive systems most of us have. If I was starting from scratch now I would have no hesitation in going the active route e.g. the Linkwitz Orion system. However I've too much invested in passive gear to trade it all in.

What has all this got to do with subwoofers? Bear with me.

I have Quad 989 speakers. According to their specs they go down to 40hz. Now there aint much happening below that so why my interest in a sub? Well because it offers an opportunity to go partially active. Ideally this is how it would work:

preamp to active xover which has 2 outputs and splits the signal between low frequencies (say 80hz and below) and everything else. The low frequencies go to a powered subwoofer (which has NO inbuilt crossover, just a volume control) and the rest of the signal goes to my power amp which drives the 989s.

The principal advantage of this set up would be that my power amp and main speakers would not be having to deal with those difficult bass frequencies and related low impedances. Relieved of these onerous duties my power amp would be able to perform much better than at present.

Finding a suitable active crossover is easy but so far I've not been able to find a crossoverless sub (although some of the more expensive ones have bypasses).

The alternative is a sub like the Velodyne DDs that have line level inputs and outputs, which would enable you to do something similar:

preamp to sub which splits off the 80hz + frequencies to its line outputs and then on to the power amp that just drives those higher frequencies through the main speakers.

Without wishing to hi-jack the thread, I'd be interested in other peoples views on this or indeed if anyone knows of a good crossoverless or even passive sub?

Ian

 

Ian, I'd reccomend getting a Velodyne DD or a Revel Sub15/30..

let them take the hard work out of it for you, and have room measurement software and EQ to meet the room thrown in.

I've only recently used the downloadable software - which basically tells you what to set your EQ to for your room.. why didnt I do it sooner? (couldn't be arsed is the honest answer).. but I should have, because it sounds loads better now.

I honestly believe these are the best options out there, until you decide to spend many thousands of pounds constructing something huge, and have the room for it.

 

I agree with bottleneck. I got a Velodyne DD-15 at about the same time as he got a Revel, and we are both very satisfied, I believe.

I too only did the full room correction recently (due to a wish to update the internal software first) and I feel the same way. It was a revelation seeing and hearing the results of some annoying room resonances tamed.

I'm not aware of a review that commented much on the passthrough transparency. The Stereophile review http://www.stereophile.com/loudspeakerreviews/604velodyne/index.html used a DD in pass-through with Quad 989s and it turned out very well. Personally I use a separate AV LF output.

 

I use subwoofers in both my systems, and proved to visitors, again and again, that either system sounds much better with the subs and digital crossover...

I did try the "REL" passive high-level connection in both systems, but it defenetely sounds worst, probably because the amplifier and the speakers have to work harder...

In Riga I have full-range speakers and tubes...

 

Thanks for the feedback everyone!

The reason I started this thread is because I DO actually have a Revel in my system right now, which I'm trying out. My initial impression of it is that there is a very slight drop off in overall transparancy compared to what I am used to- not necessarily a reduction in information but rather some of that 300b delicacy and cohesion, which is normally left delightfully unveiled (a topical issue ) by the MF passive pre- difficult to explain what I mean here but the sub does appear to get in the way a bit- although you really wouldn't know it unless you knew what was before.

There is also the introduction of a little hiss through the main speakers (and perhaps a very slight increase in hum?), which wasn't there without the sub. This is not welcome in a small room where the listening position is quite close to the speakers.

However, I must stress that I have not even got round to correctly positioning the sub or using the eq software yet! So, my impressions are merely initial ones and unfair at that.

That said, I was also playing acoustic music without any deep bass content, where proper set up of the sub might be less necessary.

 

Maybe you have a ground loop...