[AngelEyes]

I thought I would share some useful links for my fellow DIYers. If I can design, build and use one of these and ditch the BFD I will be a happy bunny.

ESP - The Linkwitz Transform Circuit

TA Speaker Topics - Designing a Linkwitz Transform

Linkwitz Transform Design Program

http://www.trueaudio.com/downloads/linkxfrm.xls

If you find any other useful links or tools, please let me know.

Adam

[j0hn]

open active crossovers Library

[Moonfly]

Well, this could be a nice beneficial side effect of my delayed start in the building department.

Cheers Adam!

[Russell.Williams]

Don't forget that these have to be applied at the line, not speaker level. You will therefore have to make a box that fits in the signal cable, not the speaker cable.

I had half an hour spare tonight and managed to effect a very good approximation using a BFD that wa snear as dammit what REW predicted in my DIY thread. If going this route, I'd work out the gains/slopes with a BFD and then build an LT that mimics your best effort as you will gain a flatter response boost sub 30Hz.

Russell

[Moonfly]

There must be something available you can buy, like a manual LTC. t's really only like a PEQ, but woks the other way around so to speak. Something as small as the antimode would be nice, the BFD is hardly a discreet unit. Sounds like though, if I want to add a LTC (and mimicking M&K would suggest I may have to in one form or another), then I may need a BFD to design it, in which case I may as well st stick with it I guess

[AngelEyes]

Apart from the fact a BFD introduces hum in my system, would there be any SQ benefits of using a LTC over a BFD? Would it add a delay to the signal as the BFD does?

My gut feeling is a well built LTC would be better but I have no idea if this is true or not?

Adam

[Nimby]

I found this to practice your soldering skills:

Linkwitz Transform Subwoofer Equaliser

[Moonfly]

Originally Posted by AngelEyes

Apart from the fact a BFD introduces hum in my system, would there be any SQ benefits of using a LTC over a BFD? Would it add a delay to the signal as the BFD does?

My gut feeling is a well built LTC would be better but I have no idea if this is true or not?

Adam

If M&K (as they were!) had it as the eq of choice, then its good enough for me.

[Nimby]

What about room modes? You still need a BFD however perfect the nearfield or theoretical response.

[Moonfly]

I intend to invest in an EQ-1 at some point. Depending how the finished product reacts to my room I can rule out the antimode, as I could hear no real difference between manual tweaking and the antimode. Thats was with the PB13U though, I no longer have the benefit of port tuning, variable phase, PEQ and room compensation.

[AngelEyes]

Originally Posted by Moonfly

If M&K (as they were!) had it as the eq of choice, then its good enough for me.

We are talking M&k here so it would have been their EQ of 'cheap'

Adam

[IronGiant]

Not being an electronics buff My understanding is that anything with digital processing in it will most likely introduce a delay, whereas an analogue crossover won't...

Dave

[Moonfly]

Originally Posted by AngelEyes

We are talking M&k here so it would have been their EQ of 'cheap'

Adam

Cost and value are two completely different things , and I think the subs M&K produced speak for themselves. I look at it this way, if thats what they can do with cheap parts, then they, or rather he, must have known what he was doing

The difficult bit is going to be designing your LTC to suit your particular sub, and perhaps unfortunately its going to be optimised for only your room, unless of course you test your sub in an anechoic chamber and eq it from there.

[AngelEyes]

Originally Posted by Moonfly

if thats what they can do with cheap parts, then they, or rather he, must have known what he was doing

Yes but think what you could do with better parts, after all you already have vastly superior drivers.

Adam

[Russell.Williams]

Originally Posted by Nimby

I found this to practice your soldering skills:

Linkwitz Transform Subwoofer Equaliser

I'd downloaded that .xls at work and couldn't find the website again at home. Thanks for that.

Russell

[Russell.Williams]

Originally Posted by IronGiant

Not being an electronics buff My understanding is that anything with digital processing in it will most likely introduce a delay, whereas an analogue crossover won't...

Dave

It'll just introduce phase shifts instead....

Russell

[IronGiant]

Thanks Russell, see I knew I knew nowt

Dave

[Nimby]

Big subwoofers aren't allowed phase shifts. You can't move them about.

It's long overdue that there was a simple and cheap, line level, phase shift box for those of us handicapped by subwoofer immobility.

[IronGiant]

We could design one and call it the Pink Trolley

Dave

[Nimby]

Originally Posted by IronGiant

We could design one and call it the Pink Trolley

Dave

Just as long as it isn't triangular...

[j0hn]

Originally Posted by AngelEyes

Yes but think what you could do with better parts, after all you already have vastly superior drivers.

Adam

If it made that much difference there would be modded units flying around. Ken would have done his own he would have done some for friends, it would have leaked somehow. I dare say what you get is pretty much the best that m&k could do. Unless there are modded units out there?

[AngelEyes]

Originally Posted by j0hn

If it made that much difference there would be modded units flying around. Ken would have done his own he would have done some for friends, it would have leaked somehow. I dare say what you get is pretty much the best that m&k could do. Unless there are modded units out there?

Very few manufacturers produce the 'best they could do', it wouldn't make financial sense. To assume you can't improve on a manufacturers product when you aren't operating within the same financial, cosmetic, size, weight etc. restrictions is a bit pessimistic IMO.

PP designs are a special case admittedly and I doubt Dan will get an improvement in perfromance over a conventional design proportional to the investment in his superior drivers. The main benefits of PP seem to be when using cheaper drivers as in the M&K designs but I very much hope Dan proves me wrong and a PP design is even better with better driver.

Adam

[j0hn]

Originally Posted by AngelEyes

Very few manufacturers produce the 'best they could do', it wouldn't make financial sense. To assume you can't improve on a manufacturers product when you aren't operating within the same financial, cosmetic, size, weight etc. restrictions is a bit pessimistic IMO.

PP designs are a special case admittedly and I doubt Dan will get an improvement in perfromance over a conventional design proportional to the investment in his superior drivers. The main benefits of PP seem to be when using cheaper drivers as in the M&K designs but I very much hope Dan proves me wrong and a PP design is even better with better driver.

Adam

you misunderstood what I said Adam. I didnt put any financial constraints. I said Ken would have built one for himself, he would have modified his friends. The cost would not come into it. Yet we dont see any leaked info so I dont think his products could have been bettered.

[AngelEyes]

Originally Posted by j0hn

you misunderstood what I said Adam. I didnt put any financial constraints. I said Ken would have built one for himself, he would have modified his friends. The cost would not come into it. Yet we dont see any leaked info so I dont think his products could have been bettered.

You can't call a lack of evidence for something existing, proof that is does not exist. There are many reasons why Prototypes or custom products if they did exist should remain out of the public domain.

The very fact that M&K, probably more than any other manufacturer, had so many versions of the same or similar products is because KK was always improving his designs.

M&K were constantly upgrading components on all their designs, including the drivers on their subwoofers. If KK thinks his designs can be improved upon with better components, why don't you?

Adam

[j0hn]

Originally Posted by AngelEyes

You can't call a lack of evidence for something existing, proof that is does not exist.

what are you being serious? think about what your saying. Look at it this way. You make subs. Your my mate. You know your cost cutting. You soup mine up for me. You do the same to your own. Now we have to assume we both have no mates who hear our subs because if we did have mates they would listen to other peoples stuff and say 'yea its good but not as good as Adams and Johns'

its human nature to talk. We have no talk therefore ...

[AngelEyes]

I am serious, you can't prove a theory without evidence to support it.

Your theory that KK couldn't improve on their commercial subwoofers because you haven't seen some gossip about it online is a little thin at best, especially when I already pointed out he has constantly improved upon his own designs with component upgrades.

[j0hn]

I have offered my proof and evidence but im repeating myself

[IronGiant]

You have suggested a theory that relies on not finding evidence in order to "prove it" In order to get your theory accepted you need to be able to prove you have looked hard enough...

[AngelEyes]

Originally Posted by j0hn

I have offered my proof and evidence but im repeating myself

Ok, we won't go round in circles as we obviously don't agree.

You haven't responded to my point that KK did improve on his designs throughout their product lifespan with superior components. So why do you think an M&K product can't be improved upon further? The new MK company certainly do as they have also changed components on some of their products.

Adam

[IronGiant]

Just say you're going to put a "HEADROOM MAXIMIZER V" CIRCUIT in it, a logical continuation and improvement of the pioneering progression through M&K's own versions I-IV before further R&D was halted for financial reasons.

Dave