DIY upgrade from wood 6.1 to wood 9.0 with Murphy xover???

sas · « **on:** 13 Nov 2005, 12:55 pm »

Hi everyone,

I am thinking of doing a DIY upgrade of my Classic 6.1's (wood) to use the parts from 9.0's. If all works out, I would end up with wood 9.0's.
But I need some help thinking this one through.

On the parts side, I need:

-ScanSpeak 15W8530-K00 woofers ($362.50 pair from madisound)
-ScanSpeak Revelator 9900 tweeters ($416.00 pair from madisound)
-Parts for Dennis Murphy-design crossover ($139 from soniccraft.com)

On the cabinet changes, I will need to:

1. Get the existing baffle out, because the driver holes in the 6.1's are too big. MBarnes says it is glued and nailed in, but I think it can be removed with some care, and making a new one is pretty simple.

My main worry is cabinet size: when Norh introduced the Classic 6.1's they said "the cabinets are ... the same size as the nOrh 9.0 and the nOrh 6.9". However the wood walls may be not quite as thick as the 9.0's, meaning a slight difference in internal volume.

So: is this something that could be tuned afterwards with a bit of padding?

The other thing is port length: MBarnes says this would need to be made "longer or shorter to tune the bass response for the different drivers."

Wondering if anyone has an idea on hown this could be done, or even if the above issues are CRITICAL to the upgrade.

Barnes suggested I just go for some mini 9.0's, but to be honest I prefer the wood (the cabinets are beautiful) but would like to upgrade them with better drivers. The 6.1's are also 90db sensitive, and far too loud and a bit too harsh with my Le Amp II's.

Thanks in advance for any advice, comments.... (Marbles & co, are you out there?)

sas

Marbles · « **Reply #1 on:** 13 Nov 2005, 01:57 pm »

If it were me, I would sell your speakers and buy the marble 9.0's currently for sale.

Then I would DIY the murphy XO's.

If you can find a pair of wood 9.0's, they would not cost above $1000 I would think.

Maybe the seller of the marble 9.0's (agon) would come down from his $1500 asking price....

The Marble cabinets sound better than the wood, and look nicer (to me) as well.

As to the internal volume...I wouldn't worry about that too much, you could always find ways to fill it up if you needed to.

sas · « **Reply #2 on:** 13 Nov 2005, 02:19 pm »

Thanks Marbles....
I understand how you prefer marble.

but I actually prefer the look of the wood, which is why I'm intending to stick with them. WAF is a big factor -- the other half loves them too because they just blend in so well.
I don't want to sell them (shipping would be a pain), so I'll just try to upgrade.
Thanks for the comment on the internal volume not being too critical ( don't think norh are that accurate from speaker to speaker anyway). But do you have any idea on port length?

The other thing any chance you could tell be what the front baffle dimensions/holes are for the 9.0's?

BTW, I was thinking of upgrading to use the 7.0 drivers, but there is no Xover design for th 7.0's and I would have to buy Xovers from Norh, which I'm worried about because of the issues with the other xovers. And I doubt the DM Xover's would work with the 7.0 drivers. But do you think the DM Xover's would work though with the 9700 tweater instead of the 9900 for the 9.0's?

Thanks again and apologies for the bother!
[/i]

Marbles · « **Reply #3 on:** 13 Nov 2005, 02:41 pm »

Quote from: sas

But do you have any idea on port length?

The other thing any chance you could tell be what the front baffle dimensions/holes are for the 9.0's?

BTW, I was thinking of upgrading to use the 7.0 drivers, but there is no Xover design for th 7.0's and I would have to buy Xovers from Norh, which I'm worried about because of the issues with the other xovers. And I doubt the DM Xover's would work with the 7.0 drivers. But do you think the DM Xover's would work though with the 9700 tweater instead of the 9900 for the 9.0's?

...

No idea on port length, but I can measure my daughters later today.

I could only tell you the outside diameter of the holes...it's best to get that info off the Scan-Speak website, or maybe Madisound or Partsexpress.

I think the DM XO WOULD work with the 9700, but not as well as it would work with the 9900. If you ask Dennis what he would change for the 9700, I bet he would tell you, as it shouldn't be much. The tweeters are VERY similar.

Marbles · « **Reply #4 on:** 13 Nov 2005, 03:47 pm »

Port seems to be about 7" long by just under 2" in diameter.

sas · « **Reply #5 on:** 13 Nov 2005, 04:15 pm »

Quote from: Marbles

Port seems to be about 7" long by just under 2" in diameter.

thanks for that. My 6.1's are just under 2" in diameter, and just under 6" long -- close enough me thinks.

I already have the dimensions for the holes I would need in the new baffles. All I really need to know is how far down from the centre point of the baffles would be the centre point of the woofer and how far up from the centre point of the baffle would be the tweeter... If you have a chance to get your measuring tape out again I'd be enormously grateful!!!

Other quick question while I'm at it: do you think there would be any point placing the DM Xovers externally, in some kind of little box just outside the spkrs, rather than internally?

Thanks too for the tip on the tweeter - I reckon I'll go for the 9900 anyhow, the price difference between it and the 9700 is not massive.

thanks, sas

fredgarvin · « **Reply #6 on:** 26 Nov 2005, 01:28 am »

Actually, Mr.Barnes is correct, the port volume is very important in dialing in good bass response. A one inch port differance in a speaker that size is probably not "close enough". You should definately check with Murphy or one of the on-line calculators, as Marbles suggests. Good luck and keep us posted.

Gordy · « **Reply #7 on:** 26 Nov 2005, 05:22 am »

One way to adjust your port length would be to use drinking straws cut to about 5" or so and packed in just snug. Sliding them inward enmass will give you an inch or three to experiment with...