DEQx + speakers?

After buying a MC750 I am thinking of a bit of a system shuffle. I have quite a bit of kit on loan at the minute but think I might try a bit of a new direction

After reading a bit about the DEQX 2.6p I am thinking of going down this route..............(i know pc's can do it better but i like the idea of a pre amp and xover in one unit).....the DAC is useful as well.

My problem is what speakers to go for....I love the mid /treble of electrostatics but I feel the bass can be better than the Martin logans. (i have tried the more expensive active bass model and thought it was awful!)

Purely for hifi......my listening space is 6m X 3.5m....
looking at the TANNOY System 15 DMT II (or 12 DMTII....but this has a none paper cone....and i usually like paper cones ) also seems to be a waste of an internal xover??

Any ideas I have about £7k ....- £2k for the DEQX so around 4-6 k for speakers inc any subs that may be needed.

 

I think you are suggesting getting a pair of commercial speakers and removing the passive Xover. Then using the DEQX to go active. This is possible, but you had better know what you are doing when it comes to speaker design, as it is no simple matter to design a really good xover, even with the DEQX (talk to Shinobiwan on here). If I may speak freely, its a very expensive way to f*ck up a pair of speakers.

If you want to experience state of the art professional monitoring get yourself a pair of Musikelectronic Geithain RL901K active speakers. All you need to do is add a source and pre-amp, no need to mess about with a DEQX and separate power amps, for what is most likely an inferior result. Meyersound also make some nice monitors but I think my preference would be the MEG.

http://www.me-geithain.de/index.html

Sorry if I sound like a kill-joy but really the DEQX is for speaker builders, not audiophiles, so it depends which you are.

 

mmmm....ok

I have built a few speakers.....single horn full range (well nearly).............a LOT of audiophile speakers have a very simple xover.....(my previous Audionote £2.5k speakers had a very simple xover)....

I respect you opinion .......I have NO knowledge of the DEQX....maybe I may start simple ..........2way monitor keeping the internal xover with two subs...using the DEQX to xover the subs and use the room correction.(i need a pre anyway)
I quite like messing about........I have done the "pay the money for the shiny case hifi thing". I realised when I built a phono stage for £100 last year that I was wasting money and enjoyed it more than a pre built. (i am fortunate that i trained as an electronics engineer specialising in TX/RX 20years ago!!........bit rusty but its coming back...................funny how I had no interest in valves then.......but a lot of the equipment used them.....ha)..I understand different filter slopes etc. (didnt think I would EVER use any of that stuff when I learned it)

I really want passive speakers and seperate subs..........maybe mids with separate supertweeter and subs.
I feel a a few lessons with a pc oscilloscope coming on here.......

 

Is what's being suggested just bypassing a passive crossover and fitting an active crossover? Don't get me wrong, it's not something I've ever done, so I'm talking from a level of complete ignorance but why would it f*ck things up? If you know the parameters of the passive crossover (crossover points, slope etc.) you could presumably emulate those with the active crossover ... or do passive crossovers do other stuff I'm unaware of?

No plans to go active myself - right now I'm a pretty happy bunny with the sound - but its a concept that's always fascinated me and I'm aware there's a lot I don't know about it.

 

Hi Uncle,

Its tricky to simply replace a passive xover because most are not text book 2nd or 3rd or whatever filter slopes. They are a wibberly wobberly transfer function that gives a good response in combination with the natural response shape of the driver. Not only that but they take in to account the exact impedance curve of the driver. This is why you could not just replace one tweeter with another that has a different impedance curve, even if they are both 6 ohm nominal. The response will be different where they differ in impedance.

Your standard active xover just has a text book slope. The DEQX on the other hand can do all this stuff, and much more, but to replicate the original xover (and keep the speaker sounding as it was intended) you would need to reverse engineer the transfer function of the xover taking in to account the component values and the precise impedance curve of the driver (its not simply resistive) its connected to. Thats usually more than people are able to do. Listener666 being an electronics engineer is probably familiar with some computer modeling software that could do this for him, though.

Even if you did that, it would be a waste of so much functionality from the DEQX which has FIR filters, time delays, super steep filters etc.. so you would really be at the point of redesigning the entire speaker only with the same drivers. You would have an end result that is nothing like the original speaker you bought and depending on your skill may be better or worse.

So, I'd say either go with the DEQX and build from scratch, or buy a good pair of active speakers and be happy. You could go for passive mid and treble and use the DEQX to xover to subs but it is a huge waste of such a capable unit. You could get a normal pre-amp for less, and build a couple of simple active filters. A pre-amp with one of ma modified DCX2496 to split the signal would also work very well and be far less costly.

 

So in laymans terms you are saying that a good passive crossover does a lot more than just a straight crossover and just yanking the passive and fitting an active (whatever sort) crossover is very likely gonna screw up the speakers frequency response?

 

Pretty much.

 

Makes sense, but the next obvious question then is what sort of speakers would you use with an off the shelf straight active crossover? Wouldn't the results be very variable or are these always used in conjunction with EQ of some sort?

 

Most active off the self crossovers are used with PA speaker systems where exact accuracy is not so important. Really they are of very little use for high quality sound.

Something like the digital units from BSS, Behringer, DEQX are far more functional, but as I said you then need to know enough to use them correctly. You should really just buy an active speaker if you want an active speaker, and buy a passive speaker if you want a passive speaker. Converting passive to active properly requires about as much skill as designing the thing in the first place.

 

Okay, well I'll not be tenmpted to mess with me spendors then Though I believe there was an active version of em.

 

You could ask Spendor to send you one of their active xovers, of course.

 

Get some active Quested pro speakers. Roger Quested is using MC2 amps and XTA digital crossovers. If you have an MC2 you probably can negotiate with Quested to build a speaker without one amp.

 

I was using a DEQX first with an Avantgarde Trio and a Rel Stentor II sub, with fantastic result. Next I was using the Danley SH 50 with the TH 112 subs again with the DEQX, but now the DEQX was used as a really digital crossover to get in through SPDIF input and using two Altmann Attraction DACs on the SPDIF output of the DEQX. The result was much better than any other speaker my life, including the Trios. Absolutely live dynamics with two MC2 amps and Evidence Audio cabling. No harshness, brightness, and quick, punchy but smooth bass to dream of. There are no words, the equipments disappeared. Unfortunately my wife could not tolerate this setup, it is ugly like hell and takes lot of space.

 

I posed this question to a well-regarded engineer as I have been considering an active crossover. He warned me that my speakers have been eq'd with the internal crossover, therefore a complete bypass of the speaker's own network would not be advisable, although I could use the active electronic crossover in conjunction with my speaker's own crossover network. This may be different for your speakers though, but you should check beforehand.

 

I have a pair of Tannoy 15 DMTs and an MC650. They are an absolutely superb pairing (with a tube preamp, at least). Highly neutral, open, effortless. There was a small amount of SS glare (compared to tubes) but either its diminished due to the amp and new cable settling in, or I've simply got used to it. Returning to the tubes should confirm either way.

Having used several amps with these speakers (t-amp, Canary 301mkii, Avondale 260z, ZH-270), I can safely say the MC2 is the best overall match, even on its own. Biamping may indeed be even better, and not necessarily with a second SS amp. But a single MC2 is superb.

I was once advised by someone with many years studio experience that I should actively biamp the Tannoys. They are commonly used in this manner in studios.

 

cheers

Thanks.....just the sort of thing i am looking at. I have just tried my Tube pre (George Wright, which i loved with my 2A3 3.5 watt monos and Audionote AN-E).........but to be honest ......i preferred the sound directly out of the krell ikid as a pre.........very direct and dynamic through the MC750. The problem is i have to plug a 3.5mm jack in to the ikid aux in to use me turntable.....sounds good though
I am still not sure if i need to set the amp at 2/4 or 8 ohms though???

Do you think they compete with 3-5k "hifi" speakers? Would I need to use a sub?

I have seen a pair of 215's ....new for £2K....i presume its similar to a 15dmt (which i can't find new!)but with an extra driver for the bass. I am sure someone on the forum has a pair.........but cannot remember.

I

 

The 15s and 215s definitely punch above their weight and compete favourably with domestic designs at those prices. They have incredible drivers and cabinets (the latter putting some older Tannoy models to shame). However, their simple x/overs, while very good, can be improved upon.

They are very strong down to approx 40hz and then roll off without much energy below 30 hz. You may miss the last 20 hz big classical stuff or dub but might also need to spend a lot on a sub that's able to keep up!

One thing to bear in mind, is that the DMT range was designed to be used on the end of powerful solid state amplification and in this respect their high sensitivity (around 97dbl for the 15s) can be deceptive for those used to domestic speakers. Recommended amp power for the 15s is 300 watts. Although the ZH-270 is undoubtedly better than the MC2 650 in certain areas (goes deeper too!), it takes the very high damping factor of the latter to really open the 15s up fully (at least to my ears).

The 15 DMT cost about £2.8K new and the 215 quite a lot more, so £2k new for the 215 is bit of a bargain and is close to what you'd expect to pay s/h. They are meant to have a little bit of extra magic than the 15s but you need to be able to accomodate them too.

 

Couldn't agree more. DEQX 2.6 is great, if a little expensive, and the newer PDC 3 looks like a nice incremental upgrade but some design know-how is required to get the most out of the speaker/DEQX partnership. You hint at the auto setup wizard on the DEQX but using this is merely OK and when your spending thousand on speakers and digital crossover then OK probably won't cut it.

You really need to be able to take a good long and hard look at every aspect of each driver as it performs both in and out of the cabinet. This primarily means distortion plots, polar plots, impedance curves. From these and with a bit of understanding you can see where the drivers are working best and where they are most suited to crossover to other drive units. Once the strengths and more importantly, the weakness have been found for each drive unit then you can start to play around in these target area's and combine the output of all drive units to create a working loudspeaker. Then through a process of iteration, measurements and listening you arrive at a sound that is accurate, balanced and correct.

All that might sound relatively simple at first glance but there's a host of factors to account for such as power response or off axis performance, distortion, baffle step, diffraction dips, comb filtering, cone resonances, crossover types/points/rates etc. I don't mean to put you off but a digital crossover unit that accounts for all these factors and does so with an auto setup routine doesn't exist just yet so the loudspeaker designers out there still have jobs. What the DEQX does provide is an auto feature that will get the ball rolling and do so quickly but the real lure is the outright flexibility and power offered when things are taken out of the hands of that feature.

Even without knowing about such things right from the start, it sounds like your quite industrious so such a setup could work to your advantage whereby research, learning and experimentation brings incremental improvements over time. These types of setups are incredibly powerful. So powerful in fact that their real limit is your ability to make the right choices and design decisions.

 

Now that I think of it, they were usually sold in pro-audio shops as single speakers- so it's probably £2k for just one and £4k for a pair.

 

you beat me to it, i saw some ad for 215, 2k for a single speaker