New Toys!

PAC

Don't know if DIY is the right place for this but somehow appropriate!

Growing tired of just how big a compromise most loudspeakers are, I decided to design and build my own, based on using the venerable Tannoy 12 inch HPD units with modern custom built crossovers (including the necessary addition of a notch filter at the crossover point).  They have modelled very well indeed and after close on 200 hours work (design and current build time) I am close to finishing these...just another week or two to go.  An artistic impression can be seen below:

And progress "on the ground"

1.28m tall, 525mm wide front baffle reducing to 275mm at rear with curved side panels.  Weight estimated to be 70kg per cabinet when completed.  response modelled as 34Hz to 20Khz +/-3dB, so better than the Prestige Turnberry and with a smoother response through the crossover point.

This is my prototype pair and these will be finished in Fiddleback Birch (aslo referred to as Ripple Birch) with Black Walnut baffle edge strips.  Twin ported bass reflex design.

The idea is then to custom build these for RFC with finishes in a wide variety of timbers as specified by customers, but this first pair is very much a DIY R&D pair.  I may have a "naming" competition with the lucky winner walking away with a pair of RFC interconnects!

The second little project in the pipeline is something I am delighted to announce here.  RFC is shortly launching its very own custom wound high bandwidth step up transformers, 1:10 step up and custom loaded at no extra cost for individual MC cartridges.  It will be followed by a higher gain SUT depending on how well the first batch goes down.  I have a prototype taking shape (the transformers have just been bench tested and perform very well indeed...exceptionally wide bandwidth (up to 100KHz!!).  Details and photos of the initial unit to follow!  Been a busy time which is why I've not been able to contribute more to discussions.  Hopefully will have some time freed up soon!

Docfoster

I feel a cake purchase and a trip down to Dursley coming on....

Brain_Dead

Nice  :>

Alan

Jolly well done Paul, that looks like excellent workmanship. All the best with it.

PAC

Thanks Guys.  Not a great deal of progress made this past week or two as a lingering illness has slowed me up a bit, so a big push will be made next week.

I'll give you a shout Ben when the speakers are done, as a cake and speakers afternoon sounds very civilised to me!

Docfoster

Thanks!
Speakers look great. As always, your craftmamship impresses. I love the photo of all the internal bracing.
Interesting to read about the drive units you've used. I've shoe-horned in some old Goodmans Goodwoods into my system recently, and have been impressed by how much a good 12 inches can bring to the party!
The extent of my amoebic DIYing was merely to build a couple of spiked platforms for the Goodmans to stand on (my floor isn't very level, and the Goodmans have non-adjustable feet), and to disconnect the squakers and tweeters. So basically the speakers are just stereo subs running off an NVA AP30, with the Cube speakers sitting on top doing everything else. I really like the extra weight, and a little warmth that the Goodmans sub setup brings.
Looking forward to hearing your monsters when they're done! :-)

PAC

Thanks for the comments Ben but I've plenty of opportunity to mess up things yet :-) .  I'm surprised that you wanted more bass, but more can be entertaining!  Sounds like an interesting balance with the Goodmans, and a good big driver always seems to bring effortless scale to the party (a good big 'un always beats a good small 'un in my book despite some advances in speaker technology.  There doesn't seem to have been any real advances IMHO in speaker design in the past few decades, just materials science and engineering). 

PAC

...double post...sorry!

Docfoster

Thanks for the comments Ben but I've plenty of opportunity to mess up things yet :-) .  I'm surprised that you wanted more bass, but more can be entertaining!  Sounds like an interesting balance with the Goodmans, and a good big driver always seems to bring effortless scale to the party (a good big 'un always beats a good small 'un in my book despite some advances in speaker technology.  There doesn't seem to have been any real advances IMHO in speaker design in the past few decades, just materials science and engineering). 

The Goodmans sounded very good considering their age, so yes, I'd agree that speakers haven't advanced much.
I didn't really want more bass until I heard them. I just saw them going cheap and couldn't resist trying them out. My only significant complaint was that the midrange sounded a bid compressed/hard. Having heard them, I couldn't live without their powerful and tuneful bass though, so decided to experiment with combining them with with the cubes using an additional amp. The only way I could get an overall sound that I liked more than the cubes on their own was to disconnect the mid and trebble units of the Goodmans. Not sure how this effects the speakers' demand on the amp, but everything seems to be coping, so I'm guessing things are OK. Also, I'm aware that it's been something of a clumsy approach, and that some tweeking of the crossover frequency to the Goodmans bass unit would probably be desirable, but as that's way beyond my capabilities I'm leaving well alone.
Anyway don't want to hijack your thread any more...!
I am confident that there will be no 'mess up' - I know that you are a man of exacting precision and care! I look forward to hearing the final result.

Brain_Dead

Hey Doc that was quick just read it all then you sneak more on, Paul I wish I could saw in a line that did not look drunk, I would make my own to. Well done, loved to hear them some time.

best Col

PS I was banned from woodwork and metalwork at school forced to do physics and music, after a accident involving a flying bowl crashed through a window whoops, and then into the schools green house.

I learned never turn wood that is unbalanced at 3500RPM and poke it with a chisel, a good lesson at 13yrs old.

Docfoster

Col, for once I'm using a proper keyboard (rather than an iPhone), so my fingers are a blur for a change!

uglymusic

They look good, Paul.

You've been busy!

Brain_Dead

Col, for once I'm using a proper keyboard (rather than an iPhone), so my fingers are a blur for a change!

Mine look like sausages wrapped in lead, slow and heavy, key board blur here is banned miss keys an smell ting gong. sea qhat I bedn 

Docfoster

The Sea of Qhat I Bedn...
Isn't that what became the Persian Gulf...?

Brain_Dead

Pushing Golf with dead battery maybe. )

Brumjam

Very interesting Paul.  Would you consider making a narrower pair of these, possibly using a 10-inch driver?  I was very impressed when I heard a pair of Turnberry's last year at Scalford but I'd never sneak the retro styling past my wife.  Looking to get a similar sound but in a more WAF friendly cabinet with similar dimensions to those of the Kensington.

Is it possible to get hold of Tannoy prestige drivers without raiding their factory? I'm guessing not.

James

PAC

Hi James

I wouldn't recommend the prestige drivers from the Turnberrys.  They are quite good but even with a notch filter, that tulip waveguide can throw up some unpleasant distortion at and just above the crossover point.  The higher Alnico models (as used in the Kensignton) are better and are sort of modelled on the HPDs as they use Alnico magnets and pepperpot waveguides.  These, providing a notch filter is used, are more detailed and more natural sounding.

The problem with going much narrower is that the point of the 6dB drop off increases in frequency and bass sensitivity is lost.  This can be compensated for by adjusting the tuning but it also results in a smaller bandwidth and earlier roll off.  The 12 inch HPD is possibly the best unit to use and I guess you could just about get away with a 475 to 500 front baffle width, but not much smaller.  The Kensington uses a 406mm wide front baffle for the longer throw 10 inch model.

If you could get hold of the driver (and there's no reason to suspect that you couldn't order a couple from the factory through a dealership) then yes, providing I get the driver specifications, I can design and build a similar set of speakers to the ones above in any real wood finish you want. 

You'd be welcome to come and listen to the one's I'm currently building as they'll be finished in a few weeks or sooner!

PAC

Some more progress photos.  Veneering of side panels completed before they were glued to the top and base panels.  Bracing removed whilst the top, base and side panels are glues.  At this stage, the empty shells, minus the 30mm thick front baffle panel, the rear, the internal bracing and all of the internal fit out including the drivers still come to 35kG each!  They'll be twice that weight each by the time they're finished if not a little heavier (gulp):

Construction time to date has been about 70 hours and only halfway through.  Another couple of weeks, perhaps 3 weeks left before I can fire them up in anger...at least I hope it won't be in anger and that they'll sing sweetly!

Docfoster

If your hourly rate is around £1.50, I may order a pair, once I've scavved the parts...
;-)

Brumjam

Wow nice work Paul. Love the veneer.

PAC

)

Whilst I'll gladly make anyone a pair who wants them, sadly, £1.50 an hour isn't going to do it [-X .  I know I'm cheap (I'd better get that in before someone else does!) but I'm not that cheap!

Materials cost have been quite staggering.  Decent timber isn't cheap, in fact it's a frightening cost.  Throw in the acoustic foam and lambswool, bitumen sheeting, fastenings and fixings, veneer (very expensive), drivers, crossovers, binding posts etc etc and it's all mounted up into quite a considerable lump!  

PAC

Wow nice work Paul. Love the veneer.

Thanks for that.  I love the ripple effect on the veneer.  I'm hoping that it comes out a little stronger when the sheen is built up a bit more. It's a little subdued at present.

uglymusic

Looks excellent Paul

PAC

Not had much chance this past 10 days to do a lot more but the bracing's now in and I've added a sloping internal base to reduce risks of standing waves and reflections becoming an issue:

I've also re-tuned the bass design for more of an EBS response.  The ports need to be lengthened to 223mm so I'm using PVC coulplers from kitchen ventilation pipework supplies to add the extra needed.  I'll use a hot air gun to shape the ends into a flared entry.

Modelling of new tuning is as follows:

Will get the rear panels on this week and start the internal fit out ready for the final stage of the front baffle assembly (laminated and very, VERY heavy).

F6 response (which the frequency response of most speakers are quoted at) is now 30Hz, which should give in-room response as pretty flat down to 30Hz so plenty low enough.

uglymusic

I'm amazed. The only thing I can turn wood into is sawdust!

Docfoster

I'm amazed. The only thing I can turn wood into is sawdust!

"Dave couldn't wait to hear what his faithful old Macbook would sound like through his new amp and stereo speakers combo..."

Docfoster

Not had much chance this past 10 days to do a lot more but the bracing's now in and I've added a sloping internal base to reduce risks of standing waves and reflections becoming an issue:

I've also re-tuned the bass design for more of an EBS response.  The ports need to be lengthened to 223mm so I'm using PVC coulplers from kitchen ventilation pipework supplies to add the extra needed.  I'll use a hot air gun to shape the ends into a flared entry.

Modelling of new tuning is as follows:

Will get the rear panels on this week and start the internal fit out ready for the final stage of the front baffle assembly (laminated and very, VERY heavy).

F6 response (which the frequency response of most speakers are quoted at) is now 30Hz, which should give in-room response as pretty flat down to 30Hz so plenty low enough.

Cracking work Paul. Quite amazing. Thanks for the updates. :-)

PAC

Cheers guys.  Well as of end of today, rear panels have been fitted and whilst I get on with the internal fit out on Friday (I'll give the panels a day before attempting to move the cabs), my associate will be getting on with the front baffle laminations (24mm Birch Ply/6mm MDF) and preparing the cut outs for the drivers before I get them veneered and I fit the ports.  The internal surfaces (all surfaces) are being treated with a 2mm layer of bitumen sheeting (bought from the local DIY store in rolls...the roof flashing stuff), so I'll first need to prime the surfaces.

Once this is done, I'll go over the sheeting with an industrial stapler to ensure that in the warmer weather the sheeting isn't tempted to part company with the cabs! Following that, I'll glue in 12mm dense wool felt to the rear panel and to the side panels adjacent to where the drivers will sit.  Then it's 40mm profiled acoustic foam to every surface.  

Finally, the "chamber" formed by the top two braces will be heavily damped with a long lambswool/BAFF mix to completely deaden it against and reflections which would otherwise get back through the driver causing distortion. The final wadding will be on the top two shelves (l 35mm layer of wadding) to help attenuate the maximum amplitude point of internal standing waves.  Then, that's the internal fit out work done.  It'll be a day per cab, so I aim to have them completed internally by next Monday or Tuesday.

Following that, it's fitting the front baffles into place, gluing and veneering.  I'll then just have the binding posts and crossover to fit to the removable rear panel.

Alan

I remain astounded at your ability and attention to detail Paul - I sincerely hope these Tannoys are as good as I think they will be! You deserve it, as a getting better treat at the very least.

Can't wait to see pictures of the final assembly.

PAC

Many thanks Alan. I'm actually very nervous as to how they'll sound as theory and design are one thing and practice is quite often another!

Some more progress. Back panels completed and glued in, panel painted in black and two coats 90 sheen lacquer applied. Cut out at base is where the removable panel for the crossover and binding posts goes. 

Same detail, other cabinet:

Spent part of this afternoon lengthening the ports for EBS tuning by using some PVC pipe couplers glued to the ends then used a heat gun and a plastic handle from a hand tool to form flares on the entry into the ports. Once completed, the rest of the afternoon was spent priming the inside of each cabinet for the bitumen sheeting. A particularly smelly and messy job! Insides now sealed:

A picture of yours truly standing next to one of the cabs to give a little scale!

Tomorrow will be spent fitting out the internals. The front baffles are now laminated and veneered. If I get time, they'll be cut for the drivers and ports tomorrow. Looking good for completion of the cabinets next week.

Docfoster

Who cares what they sound like?*
That's a sculptural work of art.

*Some rhetoric there, obviously. ;-)
Nice work coat btw.

PAC

I just hope that they don't end up becoming a very expensive plant stand!

PAC

Some more progress. Spend the entire day getting the internal damping in place. Fitting the bitumen sheeting was a filthy job. Went belts and braces and used 10mm industrial staples in case it ever thought about peeling itself off again!

Used 12mm dense wool felt around driver chamber, top and bottom panel (on top of the bitumen), then 40mm acoustic foam and finally, a 35mm layer of Monacor lambswool/BAFF around just the central area where the driver will be. This wont impede airflow to the vents which will be located below:

Fitting out the central chamber:



Damping sheeting all in and wool felt glued into place:



Close up of damping layers:



Central chamber fitted out with lambswool/BAFF:



Front baffles now veneered but unfortunately the magnets (6nr) can be quite clearly seen beneath the veneer which is a shame. As these have been bookmatched and I dont have enough veneer to re-do them, I'll just leave as-is. Holes for driver (rebated hole) and ports have yet to be cut. The underside of this 24mm slab of ply has been laminated with 6mm MDF with cut outs for the braces:



Should have the speakers completed by Wednesday.

uglymusic

Wow! I continue to be amazed, Paul.

What are your thoughts on the mystery object?

PAC

What's the mystery object then Dave?  (sorry...went over my head that one!  ))

A little more progress this evening. The removable panels for the crossovers are completed although I may try and finish them off with a better quality lacquer coat. I've now ftted the crossovers and binding posts into place and have just finished soldering the crossover connection to the binding posts which are silver plated copper:



The binding post side (rear of cabinet) can be seen next to the inside containing the crossover. I've rebated the panels and added some compressible draught excluder strips to act as gaskets:

uglymusic

The mystery object is for me to know and for you to guess... 

Brumjam

Cracking work Paul. You don't hang around once you put your mind to something do you? :-). That veneer looks lovely - high WAF.

PAC

Just back from the workshop. Both cabs received their 2nd coat of lacquer. The polystyrene in the pictures is just there to plug the holes during lacquering and aren't some new fangled driver design! Some pictures as promised:

Have yet to fix the edge strips which are made from Walnut. They're all ready and have had radii machine on the baffle edge. Also out of sight are the custom made baffle frames machined from a solid lump of ply (magnets now glued into place and the magnetic covers work really well. 6nr 10mm diameter by 3mm deep magnets in both the speakers and the covers are about perfect).

Some more pics:

Close up of side panel after 2nd coat of lacquer:

Rear view

Side view:

View from a step ladder!

50mm deep plinth which protects cabinet. Its curved to the same profile but stepped in:

The cabinets just need a final slight sanding, 2 more coats of lacquer, the edge strips gluing into place, the grills finishing and the drivers and crossovers fitted in.

I reckon another 3 to 4 days. Awaiting more lacquer which won't be here until next week.

Brain_Dead

Lovely work Paul, very nice.

trioleo

You are a craftsman Paul, I hope they sound as good as they look.

Did you spray the lacquer on?

did you build the xovers yourself?

regards  Al

PAC

Thanks chaps

You are a craftsman Paul, I hope they sound as good as they look.

Did you spray the lacquer on?

did you build the xovers yourself?

regards  Al

The work was carried out between myself and my associate who undertakes most of RFC's cabinet making needs.  Between us, we've racked up over 200 hours on the design and build so far with another 15 or so hours left.

The lacquer was sprayed on (water based) and sanded between coats.  There'll be another 2 coats to apply before they're finished.

The crossovers were originally built by Mark Prichard ("betterbuyvalves" on evilbay) but I have since found a few little things that need doing to them such as moving the HF inductor and either removing or changing the values of the amended circuitry (Mark has used some "tweaks" to the original circuit for better detail but I find the result is too bright).  I'll probably end up rebuilding them using foo components at some stage!

PAC

Some piccies of the finished article.  Some fine tuning to do but they sound pretty decent to me!

Rear view of curvy derrière:

Binding posts on removable rear panel which also houses the x-overs on the inside face:

uglymusic

Very nice. I like the light wood.

Docfoster

ooo.... ahhh...

=D>

Alan

Lovely colours there, beautiful wood. and so well finished too - well done Paul. I like the modern twist to the look, yet somehow they are still very much Tannoys.

I hope they sound as tasty as they look! Keep us posted as you tweak them, I hope they become everything you hope they will.

PAC

Thanks guys.  They need more work to cure over damping of the mid range so I'll have a play with removing internal wadding and have another look at crossover values to see if I can get them properly voiced, but on the whole I'm very pleased with them.  The only thing I under estimated was the weight.  They come in at a good 75kg, possibly more than that, so moving them is a PITA!

Docfoster

Watch that back of yours.

Docfoster

Btw paul, my last post there was an expression of concern and not some dark and macabre threat!

PAC

Mid-range hole cured!  Crossovers weren't right so I've designed some of my own to more accurately reflect the original Tannoy specifications and finished building them yesterday.  Sound quality improvements are night and day better from previously. These speakers now have epic scale, a full, rich midband and sound very clean and undistorted even when driven hard. My handi-work with the crossovers (I used custom PCB's):

 

uglymusic

I continue to be amazed with this project.

Docfoster

I continue to be amazed with this project.

Quite. Paul, when will you be fitting the time-travel widget?