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Actives.

hearhere

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This seems to have become a bit of a myth - that when you apply DSP over the whole range, you lose top end sparkle. Not so in my experience.

Firstly, if you are using DSP as the basis for the crossover, then there's no escaping the fact that DSP is being applied over the whole range.

Secondly, if what is being referred to is applying EQ across the whole range, then that is certainly a choice - and one of the choices that can be made is to enhance the top end sparkle by de-emphasising the rest of the range. In the more sophisticated approaches to DSP such as Dirac, this is formalised by allowing the user to define a "target curve" that tells the DSP engine what the desired FR profile should look like - and its shape is under the user's control.

Certainly, with powerful tools like DSP, there is enormous scope to screw things up if you don't know what you are doing, but there is also enormous scope to create a FR profile that actually matches your listening requirements.


If you are using an amp with DSP room correction built in (eg Dirac in NAD or RoomPerfect in Lyngdorf) the full range signal from the preamp either bypasses the DSP (filter off) or is subjected to it (filter selected). This happens to all frequencies even if the version of Dirac (as mine is) can only adjust sub 500 Hz frequencies.

I have Dirac in my NAD M33 and I've used RP in a demo Lyngdorf 3400. When the signal is subjected to a filer, there is no doubt whatsoever that the top end sparkle is compromised. This can be easily demonstrated with speakers that offer an abundance of sparkle! In less good speakers, this loss of detail may not be noticeable.

There is no choice about this - I’m not saying that DSP is all bad, but in full-range amps you cannot prevent the higher frequencies from this DSP circuit. Unless, of course you split the incoming full range signal into bass and the rest before DSP and amplification and DSP is applied only in the bass amp . Work it out, this is the only way to protect high frequencies from DSP, but of course bi- or tri-amping is required to achieve this.

DSP can offer an apparent improvement in sound quality but it should (as others have said) be used as a last resort. There are plenty of other steps to be taken that should negate the need for DSP, but some systems (mostly multi-speaker AV ones) are complicated and the easy route is to bung DSP at the problem.
 
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tuga

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I couldn't agree more. I've built DIY speakers in the distant past but followed precise drawings from established and well-respected brands - in my case the Wharfedale Airedale from the 1970s. This was their top-of-the-range model and Gilbert Briggs stated in his "Cabinet Handbook", "Although difficult or probably impossible to make at home, we are including drawings as they may be helpful in more remote corners of the earth". Whether he was referring to Guildford, I doubt, but it presented me with a challenge - I had to build an Airedale. I did so, complete with sand-filled panels, quarry tiles, 15", 8" and 3" Wharfedale drivers and XO, all in my home-built huge 6-sided cabinet. I was very chuffed and went on to build a second - for stereo! How they actually measured is another matter, but to me for 20 years or so they were the dog's bollocks! They went through several changes ending up with KEF drivers - 139B "race track" woofer, B110 mid and T33 tweeter - all now facing forward. Bigger bollocks as far as I was concerned!

How good these speakers would have been with a bit of DSP to smooth out the response curve, I can only imagine!

Now, with the benefit of DSP, DIY speaker designers for can cut corners but, as you rightly say, some of the sparkle will be lost from the top end, unless they tread carefully and apply it only to the bass – with multiple amps in an active system.

Digital Signal Processing in speakers can be used for crossovers (filters and driver EQ) or Digital Room Correction.

If the former, any good designer will know that the frequency response should be flat on-axis at 1 metre.

DRC should be performed on in-room response measurements below the transition frequency (~2-300Hz depending on the room) only. Above that it should be done using the on-axis anechoic response and you will be EQ'ing the speaker not the in-room response. EQ'ing in this case may be a correction of the speaker's inherent response or the applying of a tone curve (adjusted to the listener's taste).
 

hearhere

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What if you have the full version of DIRAC which measures/adjusts to 20Khz ??
It is more likely to make matters worse than better.

With the sub-500 Hz version, the top end is compromised by the additional processing circuit in much the same way it would be in old amps featuring tone controls or graphic equaliser. These methods of signal processing have been largely removed from amps, but surely DSP is a more aggressive processor?

The full frequency version certainly allows you to manipulate the top part of the frequency curve, but why should you? These DSPs are designed to correct the response that arrives at your listening position after being buggered up by your room’s acoustics (or just as likely by poor speaker setup!), but high frequencies aren't buggered by your room's acoustics - only the bass is - generally speaking. Yes, like the old treble control, you can boost high end but that doesn't eliminate the fact that these high frequencies are unnecessarily processed and lose some of their sparkle.
 

LSPC

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Linns Exakt system seems quite useable I am very impressed with it over their activ crossover cards, and can be used with other speakers as well as Linns range of speakers

There are also people who will write exakt filters for most speakers when using Linns amplifiers (Exaktbox)
 

fredbatch

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Talking of which...

Here are an old pair of AE speakers which I have refurbished and converted to active, replacing damaged mid/bass drivers with alternatives, stripping the original tatty vinyl wrap and respraying the cabinets and stands.

The passive crossovers have been removed and after measuring the characteristics of each drive unit to obtain impedance curves and T/S parameters, I have configured bespoke active digital filters using “Linn Exakt Design”, an FIR based linear phase Crossover design “engine”.

As well as controlling crossover points and roll-off slopes it provides magnitude and phase compensation across the full frequency spectrum with respect to the listening position. Additional filters are incorporated to correct for baffle step and it is also possible to compensate for cone breakups or other known anomalies. Combined with standard calculations, I used REW FR measurements to feed back into model computations.


AE.jpeg exakt.jpg


Inevitable but unwanted LF room modes are mitigated using, in this example, the highly compatible and well integrated Linn Space Optimisation tool.

SO.jpg pan.jpeg

Unfortunately, the original speaker design was full of holes, so at some point I’ll probably do a bit more work to convert them to sealed box alternatives.

I think I paid about £150 for the original speakers and resurrecting them in this new guise after much neglect has been quite a fun project. Being able to quickly repurpose pretty much any loudspeaker with these tools opens up many avenues.

Precise pan matching is surprisingly often overlooked with this kind of thing. Now I’ve got the finish I want, I’ve just got to make sure I don’t fry the drivers.
 
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EddieRUKidding

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Manticore goes back a while!, think I had a Dual at the time...Systemdek,Michell...fancied the Syncro but bought a Planar 3. Happy days before I got into serious hifi! 😀.
My First Nad was a 3120 and first turntable a 5120 (plastic fantastic), so I started at the top ;)
The Manticore Is what I traded the 5120 in on in 1984 and it still sings like the day I bought it, I it ain't broke don't fixed it I say ;)
 

Pedro2

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One draw-back with actives is that they have more that can go wrong inside. One of my Hedd's started playing up recently and I sent it back for replacement or repair. I've now got it back and it's working again. Problem appeared to lie in the power saving automatic shutdown facility - it was shutting down while playing! Also turns out that I could have probably sorted it myself as there is an online tool from Hedd that allows for firmware updates (including an option to turn off power saving).

Pleased it's back, as delivery of a new speaker from Hedd is currently looking like a 6 month wait.

I would love to have a quality power amp and passive speakers here to compare side by side with my present active system - I don't really miss the box swapping/upgrading although there's some fun to be had with it. I also find the DIY active speaker stories fascinating - might give it a whirl at some point.
 
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Chumpchops

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My powered, to active, to active with DSP, to all in one EQ etc - speakers journey since 2008, is as follows:

Audioengine A2s
Audioengine A5s

Dynaudio Focus 110a

iLoud Micro Monitors
iLoud MTMs

Buchardt A500s

….still have them all dotted around my sonic empire. I listen to more music than I ever did with separates, and am no longer even slightly intrigued or concerned ‘what’s in the box?’ at the component levels.

i let the clever folk do the matching. It’s very liberating and the lack of domestic clutter is also helpful in calm living.
 
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Pedro2

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One good thing with ATC, a very simple design
Yes. I agree. Fortunately, when my Hedd was out for repair/return, I could still use my AE1a (still waiting to go on eBay). The AE1a, like ATCs, are a simple design (type AB amps, active crossovers, drivers and no DSP).

I still rate the AE1a as fabulous active speakers and at £1000 new, amazing bang for buck. The Hedd's however, do have the edge to my ears (and our 12 year old son's ears - his are much better than mine). They just dig up so much detail but without sounding harsh. At approx £1500 a pair, I can throughly recommend them (Hedd Type 05 mk2), although I combine both the AEs and Hedds with a quality small sub - the sound is a combination of both.

Acoustic Energy AE1a and Hedd Type 05 mk2 - both great little speakers (with a big sound).
 
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Tony_J

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I also find the DIY active speaker stories fascinating - might give it a whirl at some point.
Well worth it in my experience. I have no idea how mine stack up against commercial offerings, but the sheer satisfaction of listening to a system that you have built yourself is priceless.
 
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