Soffit mounted 15" Tannoy Dual concentric project - Page 3

Charles Darwin · 29th November 2012, 08:29 PM

I am using 3 MC2 amps, one T series and two MC series ones (predecessor of the one I linked to) and I can only hear any fan noise when I'm really quiet and no music is playing.
Bought all mine s/h, one came out of the Abbey Road mastering suite but I don't know if it was in the same room. That was at the time when Abbey Road still used Quested monitoring and before B&W paid them to use their stuff. According to Roger Quested MC2s are the best amps by far. All I can say is that you'd have to prise them out of my cold, dead hands.

I also got a QSC (JBL badged) which sounds like a helicopter taking off in comparison.

Lucky man, I quite like Living Colour.

Actualsizeaudio · 29th November 2012, 08:49 PM

Quote:

Originally Posted by w_oswald

Hi, Mike!
I'd be very grateful if you could share some details - possibly even a close-up picture or two - about those "Hard Edge" surrounds.

https://www.dropbox.com/s/931ol96c1pl5yye/IMG_3280.JPG
https://www.dropbox.com/s/xv4deywy4xv9wfw/IMG_3281.JPG

w_oswald · 30th November 2012, 05:28 AM

Mike, thanks so much for those pictures - very helpful! So, although there are any number of aftermarket sources for the foam type surrounds, I have been unsuccessful at turning up a supplier for the type pictured (treated fabric, double roll) that will fit the HPD 385. Anyone know of one, or am I gonna have to make them myself? (No clue as to how I'd do that, b.t.w.

)

Charles Darwin · 30th November 2012, 06:51 AM

Lockwood Audio:Lockwood Audio

Charles Darwin · 30th November 2012, 10:02 AM

Just to clarify:
If you want to get rid of the HPD foam surrounds you have got two options.
You can either go with the Lockwood 'hard-edge' HPD cones in which case you end up with a driver that is technically similar or identical to the HPD or you can use use Monitor Gold cones in which case you technically end up with Monitor Golds ie slightly higher efficiency at the expense of bass extension.
In both cases you will end up with a substantially higher power capability due to modern former material and glue.

If you go the MG route just do not be tempted to sell them as Golds which command a much higher price than HPDs as that would be tantamount to fraud.

PS: Many foam surrounds sold are not specifically made for Tannoys. They are slightly larger and have to trimmed and cobbled which is not going to be perfect as the resulting joint will be stiffer than the rest of the surround. To the best of my knowledge there are only 3 sources for genuine surrounds world-wide: Lockwood Audio of London, Speakerbits and Speakerparts (not 100% sure of the names) of either Tampa, Florida or Australia. Lockwood is the only one actually recognized by Tannoy themselves.

Actualsizeaudio · 30th November 2012, 11:42 AM

Quote:

Originally Posted by Charles Darwin

Just to clarify:
To the best of my knowledge there are only 3 sources for genuine surrounds world-wide: Lockwood Audio of London, Speakerbits and Speakerparts (not 100% sure of the names) of either Tampa, Florida or Australia. Lockwood is the only one actually recognized by Tannoy themselves.

After seeing how nice a job they did on these, I wouldn't hesitate to pull the drivers from the cabinets and send them to Lockwood. They really did what looks at least to be a perfect job.

The gentleman who sold me these didn't tell me about the HPD, vs. Gold cone, just the hard edge, vs. foam surrounds.

Charles Darwin · 30th November 2012, 12:54 PM

If you were closer to London you could actually take them to Lockwood in person and watch Roger do the job. He is quick and tidy but then he has been doing it for decades!
It is however quite possible to do it yourself, posting those drivers safely can be quite expensive.

In all honesty I don't think it is that widely known that you can use Gold cones to replace HPDs and in these days of nearly unlimited amp power most probably choose bass extension over efficiency. Also HPD cones are heavier than Gold ones and so should reduce the danger of break up.

Actualsizeaudio · 8th December 2012, 11:44 AM

OK, so I've got my carpenter lined up for the project the 2nd week of January. Time to get serious.

If I simply try to build a 300L cabinet, with proper bracing, how do I arrive at the final dimensions? I've been reading a lot of different opinions on wether or not the Golden Ratio is the best ratio for me to adhere to. Also, since the back and sides of the speaker will be hidden, wouldn't it be useful to make all of those non parallel to avoid internal standing waves? Does anyone want to make a few dollars and design this thing for me? I don't have any cad drawing capabilities, and I'll need some sort of plan to go off of.

However, before I commit to that I suppose I need to make my mind up regarding the bass driver. I'm leaning towards doing it for several reasons. While I do have 2 capable subs, I would prefer all of the sound coming from a singe source. I'm just not sure how this changes the requirements of the internal volume of the cabinet. Also, it certainly adds cost to the project. It will be very useful for me however to have extended bass response with this system since it will be my set of client pleasing monitors.

Which leads me to another issue: Power handling of the drivers. As of right now I have a Bryston 4B, and a Bryston 3B. My plan was one for the high, and one for the low component of the Tannoy. However if I add a bass driver I have a few options: 4B for bass driver, 4B for Tannoy woofer, 3B for Tannoy horn. Or I could go 4B for bass driver, 3B for Tannoy woofer, and a smaller amp, possibly a topping T amp for the horn. I'm concerned about the power handing of the horn. Should I be? In my studying of other tri-amped main systems it seems the high driver has a much smaller amp than the other drivers. Sorry Charles, the MC2 amps are going to have to wait till I actually get this thing up and running, and I actually find a way to stay within budget! Is a 100 Watt amp on a high driver of a Tannoy Dual Concentric over kill, and possibly dangerous?

Charles Darwin · 8th December 2012, 01:05 PM

If you cross high in the 150-200Hz region the box for the Tannoy can be quite small and sealed, 40-50L should do.
In which case the size of the bass cab depends completely on the woofer you decide upon.

To go low Tannoys need huge ported boxes ie the 300L you are eyeing up. In a sealed box they will roll off somewhere between 150 and 200Hz regardless of size. I just whacked the HPD numbers into an online calculator and it gave me 34L with a 1dB drop at 120Hz. So if you remove the requirement of low bass from the Tannoys you also remove about 90% of the size requirement.

Golden ratio should matter little for soffit mounted speakers. Just make sure that none of the internal dimensions is a multiple of another. I ended up using 46L for my 12" Tannoys with the internal dimensions all being prime numbers in cm.

Amp-wise I'd go 4b for bass, 3b for woofer part of Tannoy and whatever else you can find for the Tannoy treble. 100W into 8Ohm seems about right, the Tannoy treble is a quite rugged device. I think it officially takes 25Wrms but it may well be a 16Ohm unit (I never measured its impedance) so 100/8 would give about 50/16 or twice the rms which is a good rule of thumb anyway as you want plenty of clean headroom.

At the moment you really have to decide what to do about the bass since that influences every following step you'll take. I'd still go with the Volt RV3863, there is a reason Quested and PMC use these. It'll give you 29Hz out of 200L, so even with the extra woofer you get to stay below 300L total. PMC claim a usable output down to 17Hz using that driver in a transmission line which makes sense since t/ls should roll off less steep than ported and I take the 17Hz as a -6 or -10dB figure.

AndrewT · 8th December 2012, 02:07 PM

The 15" Tannoys generally need 200Litres and more, of vented box for extended bass response.

If instead you go a dedicated bass driver in it's own box then I would use a "butterworth" roll off for the big Tannoy. Charles gives indicative size & frequency for this that I have simulated (but never implemented) in Winisdpro. The Tannoy could then have a single pole active filter added to give an L-R crossover into the bass only driver.

I would direct drive the Tannoy Horn with a 25W ClassA amplifier using a capacitor to protect the Horn from DC & LF.

30th November 2012, 05:28 AM	#23
w_oswald diyAudio Member Join Date: Jan 2010 Location: Manitoba	Mike, thanks so much for those pictures - very helpful! So, although there are any number of aftermarket sources for the foam type surrounds, I have been unsuccessful at turning up a supplier for the type pictured (treated fabric, double roll) that will fit the HPD 385. Anyone know of one, or am I gonna have to make them myself? (No clue as to how I'd do that, b.t.w.)

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29th November 2012, 08:29 PM	#21
Charles Darwin diyAudio Member Join Date: Nov 2009 Location: Birmingham, UK	I am using 3 MC2 amps, one T series and two MC series ones (predecessor of the one I linked to) and I can only hear any fan noise when I'm really quiet and no music is playing. Bought all mine s/h, one came out of the Abbey Road mastering suite but I don't know if it was in the same room. That was at the time when Abbey Road still used Quested monitoring and before B&W paid them to use their stuff. According to Roger Quested MC2s are the best amps by far. All I can say is that you'd have to prise them out of my cold, dead hands. I also got a QSC (JBL badged) which sounds like a helicopter taking off in comparison. Lucky man, I quite like Living Colour.

30th November 2012, 06:51 AM	#24
Charles Darwin diyAudio Member Join Date: Nov 2009 Location: Birmingham, UK	Lockwood Audio:Lockwood Audio

30th November 2012, 10:02 AM	#25
Charles Darwin diyAudio Member Join Date: Nov 2009 Location: Birmingham, UK	Just to clarify: If you want to get rid of the HPD foam surrounds you have got two options. You can either go with the Lockwood 'hard-edge' HPD cones in which case you end up with a driver that is technically similar or identical to the HPD or you can use use Monitor Gold cones in which case you technically end up with Monitor Golds ie slightly higher efficiency at the expense of bass extension. In both cases you will end up with a substantially higher power capability due to modern former material and glue. If you go the MG route just do not be tempted to sell them as Golds which command a much higher price than HPDs as that would be tantamount to fraud. PS: Many foam surrounds sold are not specifically made for Tannoys. They are slightly larger and have to trimmed and cobbled which is not going to be perfect as the resulting joint will be stiffer than the rest of the surround. To the best of my knowledge there are only 3 sources for genuine surrounds world-wide: Lockwood Audio of London, Speakerbits and Speakerparts (not 100% sure of the names) of either Tampa, Florida or Australia. Lockwood is the only one actually recognized by Tannoy themselves.

30th November 2012, 12:54 PM	#27
Charles Darwin diyAudio Member Join Date: Nov 2009 Location: Birmingham, UK	If you were closer to London you could actually take them to Lockwood in person and watch Roger do the job. He is quick and tidy but then he has been doing it for decades! It is however quite possible to do it yourself, posting those drivers safely can be quite expensive. In all honesty I don't think it is that widely known that you can use Gold cones to replace HPDs and in these days of nearly unlimited amp power most probably choose bass extension over efficiency. Also HPD cones are heavier than Gold ones and so should reduce the danger of break up.

8th December 2012, 11:44 AM	#28
Actualsizeaudio diyAudio Member Join Date: Jul 2012	OK, so I've got my carpenter lined up for the project the 2nd week of January. Time to get serious. If I simply try to build a 300L cabinet, with proper bracing, how do I arrive at the final dimensions? I've been reading a lot of different opinions on wether or not the Golden Ratio is the best ratio for me to adhere to. Also, since the back and sides of the speaker will be hidden, wouldn't it be useful to make all of those non parallel to avoid internal standing waves? Does anyone want to make a few dollars and design this thing for me? I don't have any cad drawing capabilities, and I'll need some sort of plan to go off of. However, before I commit to that I suppose I need to make my mind up regarding the bass driver. I'm leaning towards doing it for several reasons. While I do have 2 capable subs, I would prefer all of the sound coming from a singe source. I'm just not sure how this changes the requirements of the internal volume of the cabinet. Also, it certainly adds cost to the project. It will be very useful for me however to have extended bass response with this system since it will be my set of client pleasing monitors. Which leads me to another issue: Power handling of the drivers. As of right now I have a Bryston 4B, and a Bryston 3B. My plan was one for the high, and one for the low component of the Tannoy. However if I add a bass driver I have a few options: 4B for bass driver, 4B for Tannoy woofer, 3B for Tannoy horn. Or I could go 4B for bass driver, 3B for Tannoy woofer, and a smaller amp, possibly a topping T amp for the horn. I'm concerned about the power handing of the horn. Should I be? In my studying of other tri-amped main systems it seems the high driver has a much smaller amp than the other drivers. Sorry Charles, the MC2 amps are going to have to wait till I actually get this thing up and running, and I actually find a way to stay within budget! Is a 100 Watt amp on a high driver of a Tannoy Dual Concentric over kill, and possibly dangerous?

8th December 2012, 01:05 PM	#29
Charles Darwin diyAudio Member Join Date: Nov 2009 Location: Birmingham, UK	If you cross high in the 150-200Hz region the box for the Tannoy can be quite small and sealed, 40-50L should do. In which case the size of the bass cab depends completely on the woofer you decide upon. To go low Tannoys need huge ported boxes ie the 300L you are eyeing up. In a sealed box they will roll off somewhere between 150 and 200Hz regardless of size. I just whacked the HPD numbers into an online calculator and it gave me 34L with a 1dB drop at 120Hz. So if you remove the requirement of low bass from the Tannoys you also remove about 90% of the size requirement. Golden ratio should matter little for soffit mounted speakers. Just make sure that none of the internal dimensions is a multiple of another. I ended up using 46L for my 12" Tannoys with the internal dimensions all being prime numbers in cm. Amp-wise I'd go 4b for bass, 3b for woofer part of Tannoy and whatever else you can find for the Tannoy treble. 100W into 8Ohm seems about right, the Tannoy treble is a quite rugged device. I think it officially takes 25Wrms but it may well be a 16Ohm unit (I never measured its impedance) so 100/8 would give about 50/16 or twice the rms which is a good rule of thumb anyway as you want plenty of clean headroom. At the moment you really have to decide what to do about the bass since that influences every following step you'll take. I'd still go with the Volt RV3863, there is a reason Quested and PMC use these. It'll give you 29Hz out of 200L, so even with the extra woofer you get to stay below 300L total. PMC claim a usable output down to 17Hz using that driver in a transmission line which makes sense since t/ls should roll off less steep than ported and I take the 17Hz as a -6 or -10dB figure.

8th December 2012, 02:07 PM	#30
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	The 15" Tannoys generally need 200Litres and more, of vented box for extended bass response. If instead you go a dedicated bass driver in it's own box then I would use a "butterworth" roll off for the big Tannoy. Charles gives indicative size & frequency for this that I have simulated (but never implemented) in Winisdpro. The Tannoy could then have a single pole active filter added to give an L-R crossover into the bass only driver. I would direct drive the Tannoy Horn with a 25W ClassA amplifier using a capacitor to protect the Horn from DC & LF.