Introducing: the PET (SS 8545K + BG Neo3 PDR)

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Undefinition

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#1
I have been posting a bit about this on the PE board, but I wanted to share it with the international community here as well.

As you can tell, the cabinet design was "borrowed" from a famous hi fi speaker manufacturer (hint: they are a very "tribal" company). But I thought the slim, relatively small cabinet would have good SAF. It also was a good size to try out a bunch of other floorstanding 2-ways I've always wanted to hear (hence the removable baffle)

A quick add-up of the parts puts these at $500, which is a bit pricey. But put these drivers in a boutique hi fi speaker and well, you know the rest.... It occurred to me while adding up the parts that I have a lot of strange values in the XO. If anyone is serious about building these, drop me a line and we'll find the correct substitutions.

I'm out of adjectives and flowery language to describe my speakers. All I can say is that these are just REALLY good, and they're about all I could ask from a monopolar, 2-channel, 2-way, critical listening experience in my living room.

Crossover here: http://undefinition.googlepages.com/PETdiagram.gif

Frequency Response and Impedance: http://undefinition.googlepages.com/PETv.1.4.2FRandImp.gif

Cabinet = 8"W x 11"D x 34"H. (Shelved at bottom to create 22 Liters.) Vented, tuned to 40 Hz; F3 @ 35 Hz.
An externally hosted image should be here but it was not working when we last tested it.
 
#2
how does this compare to your vic-20? some minor changes in LP, does the midrange compare/differ to the older xover?
looks great! the ss has been used so may times i need to fork out and try it in a proven design.

blue934
 
#3
blue934 said:
how does this compare to your vic-20? some minor changes in LP, does the midrange compare/differ to the older xover?
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The VIC-20 are voiced a bit flatter--probably best-suited for jazz and classical enthusiasts. The PET are pretty reliable for all styles of music... now that I'm thinking of it, they sort of remind me of the way Jeff Bagby voices his 2-ways.

Anyway, in regards to the 8545K, it's not exactly an easy driver to work with (then again, neither is the DC160)... but I'm finding it more cooperative the longer I tweak it. And boy, once you get it under control, it can really put on a show!
 
#5
HiFiNutNut said:
I see a notch filter in the woofer circuit. Would you mind telling me what that is for?
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That particular "pulpy paper" cone has a bump between 800-900 Hz. it's not huge, but unless you tame it, the speaker will sound somewhat "boxy," which is not really something you want when you've just shelled out $160 per driver. If you look at the other DIY designs that use the 18w\8545, you'll see they all have some sort of series RLC shunt filter to mellow the peak out.

As for the commercial speakers that use that midwoofer (ie: WATT/puppy), I don't honestly know if they notch it as well, but I'd hope so. Once you do that bit of EQ on this woofer, it really puts out an excellent sound.
 
#6
Thanks for your note.

I use 18W8545 not 18W8545K so I don't know that problem. The 18W8545 (without the K) does not seem to have that problem.

It is a very good driver from 100Hz to 1.5kHz. But at 3kHz the 18W8545 does not sound smooth. I use high order at around 2kHz and it seems OK.

Regards,
Bill
 
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