3way Seas in a Harbeth40 SpendorSP100style

obiwan · 27th October 2007, 10:43 PM

Can anyone see any problem with this sort of design? I'm getting a quote to get made up a pair of speakers similar size and shape (widish baffle) to the HarbethM40 or Spendor SP100. I have a DEQX to do the crossover and for drivers I'm thinking of the W26FX001 for the woofer and the Crescendo tweeter. Not sure which mid would be best, the W16NX001, the W15CH001 or the W12CY001. I'm thinking more the 15 at this stage. I just thought I'd stick with all Seas as the supplier has the range and doesn't have Scan Speak etc, plus he makes great cabinets for commercial speaker companies here in Australia.

I know you'll say go plywood, but this guy uses mainly 32mm MDF and bitumen lining, so I'll just go with that. So yeah, I guess I just want advice on the drivers and whether you think its a flawed idea going wider baffle in this narrow baffle universe these days.

castlesteve · 28th October 2007, 12:19 AM

Here`s a similar themed design from Troels.

http://www.troelsgravesen.dk/3WClassic.htm

obiwan · 28th October 2007, 12:31 AM

Thanks for that. He does seem to like the Seas Magnesium drivers. So hopefully I'll end up with a more refined but simply less sensitive version of his classic 3-way. Hopefully!

jupiterjune · 28th October 2007, 01:01 AM

Obiwan-

Go for the 12's. In my experience, the breakup mode of metal domed woofers will cause audible nasties at 1/3 the of the breakup resonance peak. By setting the crossover below the frequency that is 1/3 of the breakup peak, you will (hopefully) have no problems.

I have a pair of ODIN's that I found to be unlistenable due to this problem.

JJ

obiwan · 28th October 2007, 04:47 AM

Hi JJ,

Thanks for that advice. So do you feel this 1/3 rule applies even with DEQX's steep (up to 300dB per octave linear phase crossovers)?

And if I understand you properly, you're saying that with the W12 which looks to have its resonance peak at 10kHz then you need to cross at 3.3kHz or less. And with the W15 I'd need to cross under 2.67kHz (8/3), and with the W16NX under 1.6kHz (4.8/3). I was planning on crossing around 2kHz anyway so looks like the 12 or 15 should be OK, but I'd guess the 12 would have greater dispersion, but conversely, lower sensitivity and power handling.

OB1

obiwan · 28th October 2007, 04:54 AM

Actually, in the 700 to 2kHz range, looks like the 12 and the 15 are similarly sensitive, its only the 16 that jumps up in sensitivity.

obiwan · 28th October 2007, 07:35 AM

And do you think it would be better to just go the standard TMW arrangement (HarbethM40 style) or place the tweeter between the mid and the woofer (Spendor style).

Having the tweeter in the centre makes things perhaps a little easier measuring the speaker at 1 meter with DEQX ,given that the mid and the woofer will be closer to microphone axis, as opposed to the TMW where the woofer is significantly further off axis if the mike is placed at tweeter height, potentially adding a source of error to DEQX's automatic time alignment.

Or is it more important to have the woofer closer to the midrange?

Questions questions.

jupiterjune · 29th October 2007, 12:09 AM

Obiwan-

Quote:

Thanks for that advice. So do you feel this 1/3 rule applies even with DEQX's steep (up to 300dB per octave linear phase crossovers)?

Yes, I feel it still applies. --Although, I've never tried them with a DEQX, so I could be flat out wrong on that point.

I believe George Short and Zaph have pretty much the same view on those drivers. Check out the designer's comments:
http://www.northcreekmusic.com/Pegasus/Pegasus.htm

Regarding the crossover frequencies, yes that is what I meant.

Quote:

And do you think it would be better to just go the standard TMW arrangement (HarbethM40 style) or place the tweeter between the mid and the woofer (Spendor style).

I am not sure about this one as it applies to the DEQX usage. If the speaker is tall, putting the tweeter on top puts it further back, so you get a little bit closer time alignment. I believe the DEQX has a built in time delay function ? (from what I've read), so I don't think that would be an issue.
Having the woofer and mid far apart should cause a dip off axis. But in this case the axis is the vertical plane, where you are much less likely to be listening "off axis".

Hey--do you know Lord Vader -- I think he is down your way on the globe.

JJ

obiwan · 29th October 2007, 03:16 AM

No I don't know Lord Vader. Wonder what city he's in?

jupiterjune · 30th October 2007, 12:52 AM

Obiwan-

I don't know what city LordVader is in (use the force!)

I do really like small metal coned drivers. I think they give a level of detail that is unmatched by 'paper or plastic'.

Keep us posted on how the DEQX works out.

JJ

27th October 2007, 10:43 PM	#1
obiwan diyAudio Member Join Date: Jun 2006	3way Seas in a Harbeth40 SpendorSP100style Can anyone see any problem with this sort of design? I'm getting a quote to get made up a pair of speakers similar size and shape (widish baffle) to the HarbethM40 or Spendor SP100. I have a DEQX to do the crossover and for drivers I'm thinking of the W26FX001 for the woofer and the Crescendo tweeter. Not sure which mid would be best, the W16NX001, the W15CH001 or the W12CY001. I'm thinking more the 15 at this stage. I just thought I'd stick with all Seas as the supplier has the range and doesn't have Scan Speak etc, plus he makes great cabinets for commercial speaker companies here in Australia. I know you'll say go plywood, but this guy uses mainly 32mm MDF and bitumen lining, so I'll just go with that. So yeah, I guess I just want advice on the drivers and whether you think its a flawed idea going wider baffle in this narrow baffle universe these days.

28th October 2007, 12:19 AM	#2
castlesteve diyAudio Member Join Date: Nov 2003 Location: N. Virginia	Spendor clone Here`s a similar themed design from Troels. http://www.troelsgravesen.dk/3WClassic.htm

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28th October 2007, 12:31 AM	#3
obiwan diyAudio Member Join Date: Jun 2006	Thanks for that. He does seem to like the Seas Magnesium drivers. So hopefully I'll end up with a more refined but simply less sensitive version of his classic 3-way. Hopefully!

28th October 2007, 01:01 AM	#4
jupiterjune diyAudio Member Join Date: Nov 2006	Obiwan- Go for the 12's. In my experience, the breakup mode of metal domed woofers will cause audible nasties at 1/3 the of the breakup resonance peak. By setting the crossover below the frequency that is 1/3 of the breakup peak, you will (hopefully) have no problems. I have a pair of ODIN's that I found to be unlistenable due to this problem. JJ

28th October 2007, 04:47 AM	#5
obiwan diyAudio Member Join Date: Jun 2006	Hi JJ, Thanks for that advice. So do you feel this 1/3 rule applies even with DEQX's steep (up to 300dB per octave linear phase crossovers)? And if I understand you properly, you're saying that with the W12 which looks to have its resonance peak at 10kHz then you need to cross at 3.3kHz or less. And with the W15 I'd need to cross under 2.67kHz (8/3), and with the W16NX under 1.6kHz (4.8/3). I was planning on crossing around 2kHz anyway so looks like the 12 or 15 should be OK, but I'd guess the 12 would have greater dispersion, but conversely, lower sensitivity and power handling. OB1

28th October 2007, 04:54 AM	#6
obiwan diyAudio Member Join Date: Jun 2006	Actually, in the 700 to 2kHz range, looks like the 12 and the 15 are similarly sensitive, its only the 16 that jumps up in sensitivity.

28th October 2007, 07:35 AM	#7
obiwan diyAudio Member Join Date: Jun 2006	And do you think it would be better to just go the standard TMW arrangement (HarbethM40 style) or place the tweeter between the mid and the woofer (Spendor style). Having the tweeter in the centre makes things perhaps a little easier measuring the speaker at 1 meter with DEQX ,given that the mid and the woofer will be closer to microphone axis, as opposed to the TMW where the woofer is significantly further off axis if the mike is placed at tweeter height, potentially adding a source of error to DEQX's automatic time alignment. Or is it more important to have the woofer closer to the midrange? Questions questions.

29th October 2007, 03:16 AM	#9
obiwan diyAudio Member Join Date: Jun 2006	No I don't know Lord Vader. Wonder what city he's in?

30th October 2007, 12:52 AM	#10
jupiterjune diyAudio Member Join Date: Nov 2006	Obiwan- I don't know what city LordVader is in (use the force!) I do really like small metal coned drivers. I think they give a level of detail that is unmatched by 'paper or plastic'. Keep us posted on how the DEQX works out. JJ

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