So I decided to build some new enclosures for my mo it or gold 15”. Here is some info. They basically followed the Arden design but I made them less wide, taller, and deeper. The dimensions are 19” wide, 16” Deep, and 40” tall. I made them from 3/4” birch plywood. I reused the lining material from my old Belvederes which is 1 1/2” thick for the back, top, and bottom. I doubled this up behind the driver. The sides are carpet underlay. They are bass reflex with a 16” by 2 3/4” There is a shelf half way up for bracing and angle braces on the back.
The sound is ok but there are clear frequency humps in the low mids. A frequency sweep reveals clear emphasis at two point in the lower mids. Is there anything about what I did that might explain this.
Other than that they sound great.
The sound is ok but there are clear frequency humps in the low mids. A frequency sweep reveals clear emphasis at two point in the lower mids. Is there anything about what I did that might explain this.
Other than that they sound great.
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According to Tannoy you can stick them in pretty much any sized box. This is true of any speaker but it will mean a wonky frequency response. Without reverse engineering the crossover and port tuning, the next best option would be a frequency response measurement. In an ideal world a frequency response measurment would be your best bet but getting accurte measurements down to low frequencies without the room joining in are pretty much impossible, so all you're really measuring is the room response.
Interesting thread here: Cabinet plans for HPD 385
Interesting thread here: Cabinet plans for HPD 385
Horrible thread, except for your post (#5?).
Tannoy factory enclosures are universally horrible for the older drivers. Measure the T/S and design from scratch.
My factory Arden enclosure was so resonant, I could have strapped one to my chest and used it as a bass drum in a marching band.
The problem is that people when people sell Tannoys, they remove the drivers and crossovers because the enclosures are far too big to post. The buyer asks what the best enclosure is for that driver on a forum and the usual answer is "Anything up to about 300ltr. The bigger the better". - The world must be full of badly tuned Tannoys.
Not really as they are just enough of a high aspect ratio that with the driver and vent at opposing ends constitutes a vented TL [MLTL] with 1/4 WL modes, so short of relocating the driver further down at 1/3rd or 2/5ths [i.d.] to average them out plus a little damping, then need to damp them like a TL, though won't need as much stuffing density.
GM
edit: hmm, didn't notice the huge panel brace that's tuning it somewhat like a poorly designed double bass reflex, so if they were mine I'd get rid of them and only have vertical wall stiffeners and just hardwood closet pole 'X' bracing to tie the four sides together combined with a vertical one tying these plus the other two walls to create a cab that can't 'breathe'. Wouldn't hurt to add a cross plate on edge to support such a heavy driver.........or if you like to make sawdust and don't mind the lost net Vb, Dave P10's full length holey plate braces will lock it down real good.
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Yes, it is. But don't tell the Tannoyista true believers or there will be much pearl clutching.
As an owner of Tannoy 10 inch HPD in Eaton cabinets I discovered a lumpy response even though they are supposed to be flatish. This was caused by reflection from the back of the speaker cabinet. This actually occurs with many speakers, not just Tannoy. I have worked on many designs, small to large with similar issues.
The interference from the rear creates a response with deep ripples which may stay within +/- 3dB but sounds like crap. This can be easily be detected by a measurement microphone. Putting padding at the rear of the cabinet does not help much.
My solution which I now employ as standard, is to prevent the internal space from resonating. This can be achieved in many ways, but I fill the space with wadding and pack it more densely behind the driver, than is considered normal. It will change the bass character, which will become much cleaner, but not as deep.
The interference from the rear creates a response with deep ripples which may stay within +/- 3dB but sounds like crap. This can be easily be detected by a measurement microphone. Putting padding at the rear of the cabinet does not help much.
My solution which I now employ as standard, is to prevent the internal space from resonating. This can be achieved in many ways, but I fill the space with wadding and pack it more densely behind the driver, than is considered normal. It will change the bass character, which will become much cleaner, but not as deep.
Those old Tannoys (HPD and prior) are low to very low Qts drivers of between 0.18 and 0.24. This limits the useful box designs quite a bit with regards to extension.
The one to aim for is the Extended Bass Shelf type of alignment which usually requires a box size approaching Vas tuned to Fs. The result is that the bass response drops quickly by about 3-6dB below about 170hz and stays at that level down Fs from wherer it drops by the customary 24dB/oct. This can fairly easily be got back by placement within the room.
For Monitor Gold 15s this would mean a box of 300-350L tuned to 26Hz. Everything else is a poor compromise IMO and loses about an octave in bass extension. The worst thing is a smaller box tuned to Fs which results in unpleasant 'one note bass'.
Note that box calculators practically never come up with useful designs when faced with low Qts drivers.
I use an extended bass shelf alignment for my own speakers, so yes I know it's a handy way of squeezing more extension out of drivers with a low Q.
One note bass can come from a number of things but I think the worst offender is a badly tuned reflex box with a peak at tuning frequency (Ironically that's how a lot of diy Tannoys will be tuned). The last speakers I built were tuned quite high and in a smaller box than what would have given a flat low frequency response and the bass was very tight and punchy for a ported box.
I don't agree that room placement will bring the bass back to flat with an extended bass shelf. Not unless you do something extreme like place the speaker near a boundary, but I don't think i've heard anyone suggesting that with Tannoys.
If the Monitor Gold 15 is designed to give a flat response in a 350ltr box with a 26hz tuning then that's fine. It's only when people give an option of hugely different box sizes and tuning frequencies that I shake my head in disbelief.
One note bass can come from a number of things but I think the worst offender is a badly tuned reflex box with a peak at tuning frequency (Ironically that's how a lot of diy Tannoys will be tuned). The last speakers I built were tuned quite high and in a smaller box than what would have given a flat low frequency response and the bass was very tight and punchy for a ported box.
I don't agree that room placement will bring the bass back to flat with an extended bass shelf. Not unless you do something extreme like place the speaker near a boundary, but I don't think i've heard anyone suggesting that with Tannoys.
If the Monitor Gold 15 is designed to give a flat response in a 350ltr box with a 26hz tuning then that's fine. It's only when people give an option of hugely different box sizes and tuning frequencies that I shake my head in disbelief.
I decided not to fight the physics and accept the bass compromise for a smaller cabinet. I use a sub. This might detract from the 'magic' of Tannoys but Japanese style, where the speakers are half the room, doesn't appeal to me. It is the imaging and improved phase performance that I want to keep.
This is by far the best way to integrate them into a system. I've had lots of Tannoys through the house and the best were put in smallish sealed enclosures and actively crossed to an 18" pro driver to handle below a couple of hundred Hz or so. As well as not needing a compromise fridge sized enclosure, it removes the midbass requirements from the Tannoy cone, substantially reducing excursion and distortion and doppler modulation from cone movement.
I can almost hear the Tannoyistas "well, I never..."
I can almost hear the Tannoyistas "well, I never..."
I use my Tannoys 3way with a woofer, doesn't affect imaging at all.
It does noticeably clean up the mids a bit if you remove low bass from Tannoys. All my speakers find themselves on a wall, if it were possible I'd soffit-mount them. There is nothing to be gained from having them free-standing except from a psychoacoustic pov. In other words I get beautiful depth of field (depending on recording of course) as long as I keep my eyes closed and don't see the wall. Either side of a large window works with eyes open to some degree although it is less than optimal acoustically. Some times I have entertained myself by listening to the perceived depth of field collapsing when I look at the wall and coming back when I close my eyes again.
I agree with fatmarley tight bass is possible out of smaller cabs but you will lose extension and it might take some time to find the right port tuning without humps.
All a bit awkward I know but that is one of the oddities when working with drivers that predate Thiele and Small.
It does noticeably clean up the mids a bit if you remove low bass from Tannoys. All my speakers find themselves on a wall, if it were possible I'd soffit-mount them. There is nothing to be gained from having them free-standing except from a psychoacoustic pov. In other words I get beautiful depth of field (depending on recording of course) as long as I keep my eyes closed and don't see the wall. Either side of a large window works with eyes open to some degree although it is less than optimal acoustically. Some times I have entertained myself by listening to the perceived depth of field collapsing when I look at the wall and coming back when I close my eyes again.
I agree with fatmarley tight bass is possible out of smaller cabs but you will lose extension and it might take some time to find the right port tuning without humps.
All a bit awkward I know but that is one of the oddities when working with drivers that predate Thiele and Small.
Our miniOnken alignment tends to generate smallish boxes and articulate, nuanced bass, but only as far down as it goes.
Looking at the specs provided for the Gold 15”, it fits into a 50 litre box and reaches into the high 40s F10.
Sealed 30 litres gives a 2nd order butterworth and an XO point (ie F3) at ~90 hz.
If you want low bass it is best provided by multiple separate subs placed to combat room modes.
dave
So, I picked up a set of the hpd-385's currently in diy Arden boxes that need to be redone. Size is not an object. I'm going to remake the cabs out of wenge wood, which is ridiculously expensive and I only want to do it once. Are we talking 300L+? what about if I wanted to go sealed? (which I tend to prefer)
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