Upgrading from passive to active

I think thats a bit tough thorsten. In fact I am going to apologise for the room not the speakers. Obviously you like room independent designs and thats dandy but it isnt the only way. Just the same as some cartridges dont work in the environment of some arms so some speakers will vary from room to room. With a little bit of room treatment to correct the high frequency behaviour and the two bass suckouts I think the room would be good. Unfortuntely I cant do that as it stands for the reasons I have outlined. With the django in place, the shelves filled and a few tweaks to the crossover I suspect the problem will be largely mitagated. As it stands the system still sounds good but these areas will improve the sound no end. Almost all domestic systems would benefit from room treatment and that would seem to be the conclusion here.

 

I really can't listen to PMC's at all, Bryston's are fair amps yes, just not what I would chose due to the lack of texture and and control.
Though by using 3 amps instaead of one does redress the balance I suspect.
Nick instead of trying to put patches on the problem in a hope of finding a cure, why not try building it PROPERLY from Sctach
Save a lot of time, money and effort my old Darth Moll appriecation society chairman

 

I guess every room I have heard large active PMC's in is problematic then? Even those two studios?

It would be interesting to see the off axis measurements for the PMC's - whilst those for ATC are hardly textbook, at least they seem to ensure that the reverrbent field is unlikely to lead to brightness in most rooms.

 

Darth Moll? They seem to have plenty of control

With the crossovers I shoud be able to get any balance I like surely? Perhaps Tenson can show the final plot - I think there is still a mid treble lift. I have adjusted down since that time and will see how I get on with it.

The pmcs sounded terrible in the studio when I bought them - but it was going through a desk.

 

It was always my intention to go active and it clearly needs some more tweaking and longer term treatment. Just out of interest though what would you propose WM?

 

bbv

active cross overs are not just a tone control.
the speakers are voiced to have the designers intentions and the crossover is used to enhance room funtionality.
the idea of a crossover is to integrate the drivers not tune them like a graphic.
you are approaching the system from the wrong way.
i'd suggest listening to the advice of more experienced people.
glad to see your on the way to a good pre amp but i still regard the bryston amps as basically muscle p.a. amps of a better than average sound but no more than that.
not really a big fan of pmc's either.

 

Nick,

A full room sweep, sit down run through the results in a logical fashion. This will give you a start point from which to help you make the correct desicion.
I have had a lot of experiance with active systems and active near feild too!!!! (what, hey???)
These (at the time) had the best full adjustable x/overs/time alignement/indivdual level controls etc.
Seriously top of line amps.
yet as impressive as the sound was, ultra dynamic detailed and powerful presence.
It really didn't give that 'I'm not moving from this seat' ability, a high wow factor, but no long term musical satisfaction.
Personally I would select a pair of floorstanders that complimented the room (preferably with lesser sesnitivity), with an amplifer capable of producing total involvement & iron like grip on the drivers. Bryston are good, just not in the all round stakes.
My take nothing else.

 

Nick, so your long term plans dont include Bryston amps and you wish/intend to tweak the active's tweaters? So this isnt the satisfying upgrade that your other posts imply. Or am I missing something?

 

You can still go back to passive Nick. There's some guy called Paul selling some IB2's on HFFS. Also a pair of 7bsst (although I know you preferred the st series!).

What a coincidence. I'm sure this Paul character will soon reduce the price which is optimistic to say the least.

 

Hi,

Are you quite sure? I mean the REAL WORLD crossover (passive or active), not some idealised book concept....

If you actually take at least one of any given funloving speaker and you analyse the electrical output from crossover to the drive units you will find almost invariably that some degree of response shaping above and beyond just the "crossover" function happens and is neccesary.

If you tune the EQ and level to each individual driver you can produce systems with vastly superior channel matching and much better drive unit integration.

It is usueally the lack of the equalisation required that makes "activating" traditional passive speakers by simply adding a generic adjustable active X-over so unsucessful.

Here an illustration of my point. Picture 1 is the raw response from the drive units of a specific Speaker (project here: http://www.musicanddesign.com/HiVi.html)....



(Woofers blue, Midrange Green and Treble red)

And here is response after applying the crossover circuit:



In order to arrive at the second from the first a LOT of response shaping and equalisation is going on. If you applied "just a croosover" the result would be neither funny nor particulary good....

Ciao T

 

hi

i agree thorsten.
that is how a crossover should work.
not the way bbv is tweaking a problematic system.
otherwise the note harmonic relationship becomes obliterated.
hence i am agreeing with you and your recommendations are totally sensible to me.
this is why i am trying to get bbv to audition a proper digital crossover , same as you are i think !
i'm sure you agree that eq and crossovers are slightly different devices to adjust the system as a whole not just a tweak to a room but to get real life musical improvements.

 

Daryl - yes I know its not just a graphic eq. However the bryston crossovers supplied are not the standard 10bs and have been heavily modified by pmc to suit the specific drivers as well as having upgraded components (as the power amps do). Level matching is ONE of the roles of a crossover given the drivers have different sensitivities. The main problem is the room needs treatment - along side the replacement of the pre. After that I will address any issues that might remain. I am going to buy a behringer this week as a starting point. I will then install software on my pc, buy a mic and take a look at the frequency response in earnest. We only had about 5 hrs to listen to the old system take it to pieces assemble the new one do some basic measurements, play with the digital eq and then the django. The initial results are promising but more work is needed and some of the issues can only be addressed when i am in my own place. Obviously as I am new to room measurement and crossover tuning / eq I accept any advice with an open mind. Do remember however that my preferences are not the same as yours so I am gong to be happy with different kit. I guess I like the "harmionically threadbare" variety.

I suggest tenson post the final system plot - currently the mid and high are probably on the high side slightly on the graph. Take a look and tell me what you think.

 

WM - thanks, that exactly my plan. This is going to take more than the hour or so I have spent already and I clearly need to learn a few things in this area to get it right. What crossovers would you recommend?

Greg - merely keeping my options open. It may be I stick with the brystons. Any system can always be improved. A nice ribbon tweeter maybe?

SM - why would I go back to passive when the active sounded better in every way???

 

Hi,

Allow me for the hyperbolic effect to give you a little thought experiment to illustrate why your position is completely the reverse from that the least common of all senses dictates!

If a car manufacturer made a new "supercar" with the biggest engine and a massive topspeed, but they completely goofed up the suspension and aerodynamics so that the any slight sidewind would almost throw the car off the road and curves could only be driven at walking pace safely, who would you say was at fault?

Would it be the Car suggested that was wrong because it failed to account for real roads with curves and bumps and sidewinds, or would the road be to blame because it had not been constructed propperly (eg, flat, straight with no bends and sheltered from sidewinds?

I repeat as many times as neccesary, a Speaker that requires specific room positioning, acoustic treatments and so on to perform reasonably within an acoustically small room is a speaker counter to common sense, basic acoustics and so on. I appreciate that this condemns 99% of all speakers currently sold.

Yet that, as you no doubt are aware, merely illustrates Sturgons Law.

But, if cars where designed like current "High Fidelity" speakers driving would be a lot less safe and a fun, if a lot more interresting....

Ciao T

 

Thats hardly a fair analogy - consider my brinkmann deck. It requires external isolation to perform any where near its best. Does that mean it is "broken"? No it is just a certain type of design meant to work best in a specific environment. Like the pmc.

A better analogy would be buying a ferrari and expecting it to corner well with narrow retread tyres ... you have to get high performance tyres to really get the best out of its handling.

I dont think anything is "goofed up" with the pmc - its just a certain type of design solution.

Ok my flame proof underpants are on - let me have it.

 

I'm surprised that it wasnt possible to use the TT as your primary source. I cant really imagine a £200 DVD recorder would be much use as a source for this level of analysis. Certainly not a source you should be hanging any true conclusions on. Or am I a mentalist?

 

You are entirely correct and that is indeed part of my point. Sadly the phono stage started oscillating and then it conked out. The dvd recorder adds some harshness and when my PT de capo dac gets back from being repaired this will also no doubt improve things. We did also use the dac in the behringer which improved matters.

 

I still think that your room is too small to cope with large monitors. I would advise downsizing them.

 

5m by 7.5m (plus the kitchen adding to the length at the back) isnt that small bub. Plus when I move I will get a much bigger lounge. One of the flats I was looking at was more like 8m by 12m.

 

Hi,

Well, when I reviewed my current deck I did criticise that the supplied matching stand was overly resonant and non-suspended and thus required substantial modifications in my review. If a Turntable is sold as "use only with an additional suspension system" that's fine. If a Speaker is sold with a sticker "only use in padded cells" that is fine with me too.

If any item requires special attention well beyond and above what one might expect and this is clearly stated I'll take that as "read".

It raises the question however, "Where is it written that I cannot do that?", with respect to placing the PMC Speakers (or most others in fact) into a normal room without applying large amounts of acoustic treatment?

Note, I am not picking on PMC specifically, but rather generically at the type of design they represent.

A Ferrari does not come with narrow threaded tires for the simple reason that it would be almost undrivable that way. You would expect Ferrari to deliver you a car that is drivable (and safely so, with a modicum of care), would you not?

True.

My point is in fact that no matter how "well" this design solution is implemented, it is a design solution that is in direct contradiction and the polar opposite of what common sense and acoustics dictate.

If you like to know what a "common sense" solution to a high performance speaker looks like, check out the Legacy Whisper....

Ciao T