Onkyo S-8000 tweaks - diyAudio
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Old 20th July 2008, 04:20 AM   #1
Stuey is offline Stuey  Australia
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Default Onkyo S-8000 tweaks

Hi there,

I recently picked up a pair of near mint Onkyo S-8000's along with a load of 'matching' Onkyo components.

I expected them to sound reasonable but not great - listenable but not critically. But I was wrong; they are quite poor. The mids and highs are quite harsh and coloured.

Attached is a pic. The mfr specs are: 310mm woofer, 80mm mid/tweeter, 40mm 'supertweeter'. Crossover points 2000Hz & 9000Hz. Cabinet 65 litre, dimensions WHD 400mm x 753 x 335.

Weight 22Kg.

The cabinet is pretty solid; 22mm chipboard with some bracing and double thickness in the lower sides near the woofer.

Removal of the woofer shows that the aluminium surround is not just for show. This is part of the cast alloy one piece basket. The dust cap is vented and the surrounds are a sort of foamy cloth, fully intact. They are retained by four massive hex bolts into big T nuts, and the frame has a rubber O-ring gasket in a channel.

The crossover uses bipolar electrolytics, ferrite cored inductors and cement 'coffin' resistors and goes through a three position control for tweaking of the highs. The mid and 'supertweeter' (their term) are paper coned. It is claimed that this has response to 40KHz.

Anyway (finally) my question is to ask for opinions as to whether it may be worth doing a quick and dirty tweak by buying reasonably priced dome mid and tweets to replace the ones in there, without any changes to the crossover. I don't have time to fiddle around (too many other projects) but these have to be used or sold...(says 'er indoors...). Maybe it could cope with outdoor barbecue duty then...?

What do you reckon?

Cheers

Stuey
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File Type: jpg onkyo s-8000.jpg (28.1 KB, 97 views)
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Old 20th July 2008, 04:51 AM   #2
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Hmm "bipolar electrolytics, ferrite cored inductors and cement 'coffin' resistors"

It seems like another case of C.C.C. Crappy Crossover Components.

The bad news is that whatever performance those drivers are capable of, it's being strangled by those low grade parts in the circuit. At this point, putting in better drivers won't get you much.

The good news is that those parts are so bad, almost anything is an improvement.

[IMG] http://Nate-Diggidy.smugmug.com/phot...10_G6yvr-M.jpg[/IMG]

This is the factory x-o in a pair of Infinity speakers I have. Pretty much an example of what not to do. I bypassed the stock tweeter cap with a .1uF film & foil poly, substituted in some air core inductors and the speakers are much better sounding. Inspired by this, the x-o's are getting a complete remake and I'm changing everything but the resistor in the woofer's Zobel network. Seperate woofer & tweeter x-o boards even!
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Old 20th July 2008, 05:51 AM   #3
Stuey is offline Stuey  Australia
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I should say at this point I have scratch built a couple of my own loudspeakers, including crossovers, but I lack the experience borne of constructing many. I took short cuts where relatively expensive measurement equipment was required, just in order to see just how good they could be before I invested more. While I was pleasantly surprised by mine, I have now decided to build a pair of Zaph's Waveguide TMM's.

Back OT, are you sure that the crossovers are the current 'weakest link'? I would have thought that at this level the components in the crossover would have a more subtle effect on performance than the drivers, hence the biggest improvement would be from new better quality drivers. I'm thinking (very) poor man's NS1000. Ha Ha! (Yes, I have a pic of the NS1000 crossover, by the way!).

The look and solidity of these just makes me not want to dispose of them too quickly...!

Thanks for the input.

Cheers

Stuey
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Old 20th July 2008, 09:38 AM   #4
Stuey is offline Stuey  Australia
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Well that's got to be the shortest 'project' ever! I was stepping through a test tone CD to gain an idea of where these things were lacking, and one woofer went silent. The upshot was that the voice coil is now kaput! And it was only at about 1/5th of the power of my gainclone test amp.

I guess that's my answer then!

Hmmm, what to do with a solid 65 litre cabinet...

Cheers

Stuey
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Old 20th July 2008, 09:47 AM   #5
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If the box is solidly constucted use it for a subwoofer, using a new front face; if it's not advertise it honestly and use Ebay to pass it on, start the bidding at $0.99 and charge a bomb for postage
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Old 20th July 2008, 10:37 AM   #6
Stuey is offline Stuey  Australia
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Yep, both thoughts already crossed my mind, Dog! The box is very solid, and with additional bracing it'd be STRONG.

I'll probably pass them on via the Big E, but I'll have a think. Of course, with total honesty.

Cheers

Stuey
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Old 20th July 2008, 12:25 PM   #7
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I used a second hand box as the base for this project

First open baffle project

May help your decision
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