Soffit mounted 15" Tannoy Dual concentric project

[Actualsizeaudio]

Originally Posted by Charles Darwin

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.

This is what I'm leaning towards. Either a single RV3836 per side, or 2 in a T/L setup. I'm going to be listening to these in my studio for a long time, and the main purpose of these besides being a tribute, is to wow clients sonically and visually. I should really build them like proper recording stusio mains, and less like a pair of vintage hifi speakers, though they will sort of be that as well. I wonder if I wasn't going to go this route in the first place, if a set of 12" dual concentric drivers would not have been a better choice.

The other thing that interests me is keeping the cabinet sealed. I've always preferred sealed designs like my Klein and Hummel O300s. Plus to be honest, I'm terrified to put a 300L cabinet in a soffit mount angled down toward the listener. What is it fell out

So, do the drivers stay in different cabinets, or can they share the same cabinet? Is there a benefit to a dual cabinet design?

[Actualsizeaudio]

Originally Posted by AndrewT

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

Do you still think I would need this in a setup where I was using a digital active crossover (like I'm going to, and like Chris Pelonis' speakers do)?

Thanks so much for the input.

[AndrewT]

the Horn in the Tannoy is very sensitive.
Most Builders recommend a capacitor as protection in low to medium sensitivity active tweeters. I would expect a sensitive tweeter to be in need of protection even more.

[Charles Darwin]

I'd use separate cabs if you go the Volt route simply because I think one 200L and one 40-50L cab are easier to handle than a single 250-300L one.
You could always mount the bass cab vertical and just angle the smaller tannoy cab down.
Just keep the bass and the Tannoys close together. Ideally 1/4 wavelength at crossover point or about 2-3ft roughly.
If you go for a small enclosure for the Tannoys make it sealed, less grieve with phasing.
I see no reason not to use 24dBL-R to crossover for the same reasons.

As I said the Tannoy tweeter is quite rugged so no real need for a 'safety' cap. I'm running mine without one off a 175W/8Ohm amp for years without problems.

Not sure why you would want to run 2 Volts per side if you use t/ls. How loud and low do you need it to be?
Talking about impressing the punters: Volt also do 18" woofers! 32Hz out of 180L ported. Impressive to the customers, I'm sure but may be less so to any potential neighbours.

[Actualsizeaudio]

Originally Posted by Charles Darwin

Talking about impressing the punters: Volt also do 18" woofers! 32Hz out of 180L ported. Impressive to the customers, I'm sure but may be less so to any potential neighbours.

Yep, no neighbors, and I have had a drummer playing in my studio at 1AM with the whole family sleeping in the house. The miracle of green glue! One of the reasons I'm so surprised at some of the GG suspicion around here.

I'm leaning towards one 300L cab with one 15" Volt per side. This way if I want to listen to the system with only the Tannoy playing I can do that for fun. I do really prefer sealed cabinets, and the idea of only having to angle the one cabinet is a good one. However, that would make the front wall of the soffit much more difficult to build.

Decisions.......I'm going to give myself to this time next week to make up my mind.

[Charles Darwin]

Another idea:
The Volt needs only 200L to give his best. Build one compartment according to its requirements (it will be ported, you can find the port size on Volt spec sheets. A t/l for one driver would be about the same size roughly).
Now if you put the Tannoy into separate, ported compartment of between 100 & 150L those HPDs should reach a -3dB point at about 42Hz. Granted that is some Hertz short of the best it could do but it should be good enough for R'n'R! ;-)
When you cross in the Volts at about 150Hz the port of the Tannoy compartment has little or no effect on its workings and it should practically behave as a sealed cab above that frequency.

Advantage is that you can use the Tannoy on its own with sensible bass extension, the disadvantage is that the whole lot might get a bit bigger than 300L in total.

[planet10]

Originally Posted by Actualsizeaudio

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.

There is nothing about the golden ratio that really sets it apart from every other (ir)rationally chosen set of box dimension ratios. Moving away from a rectangular box can have more positive impact. Are you building the wall around the speaker?

I would also not blindly build a 300 litre cabinet... a quite different cabinet would be optimum for the driver used full range vrs as a mid-tweeter.

Taking the T/S Colin pointed to, a 300 litre creates a VERY ugly alignment. A quick look, and using the techniques that have proven themselves well with the "miniOnkens" suggests something no larger than 55 litre for FR use.

However, before I commit to that I suppose I need to make my mind up regarding the bass driver...I'm just not sure how this changes the requirements of the internal volume of the cabinet.

There choice larger determines the size of the cabinet.

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.

Aimingfor quality bass with the Tannoys alone would limit you to something like 55 Hz anechoic, but room gain will have a huge impact, likely takingit into the low 30s. Adding dedicated woofers should give at least that, with more impact, and clean up the midrange (biggest benefit)

Which leads me to another issue: Power handling of the drivers.

I would add a small amp for the tweeters. A class D amplifier is probably not the best choice, their greatest deficits being at the top. A class A amp would be nice. The other way to approach (and likely the cheapest) would be a BIG class D amp for the bottom, perhaps a Hypex.

dave

[planet10]

Originally Posted by AndrewT

... then I would use a "butterworth" roll off for the big Tannoy

33.5 litre & 86 Hz. I'd want to XO higher and leave the upper bass to the bass drivers. I also prefer low pressure cabinets... i'd use an aperiodic TL for the Tannoy used as a mid-tweeter.

dave

[planet10]

Using the same alignment techniques, i'd do 100 litres for the Volt, with room gain reaching into the high 20s. A much larger ML-TL would give maximum bass with minimal size (given the ap this is how i would go, one can always EQ out too much room gain). I envision a tall ML-TL for the bass, wall mounted with driver as close as possible to the soffit mounted Tannoy.

dave

[planet10]

A practical question. How big is the room? Particularily the height.

dave