New arrivals - Tannoy corner Canterbury with 12in Monitor Gold

[montesquieu]

Freshly arrived .... Tannoy Canterburys.

I've been through the mill lately with speakers after selling the Tannoy GRFs and having Autographs made, only to find at over 4 ft 10in tall and 60-odd inches wide, they didn't fit the new house :doh:

The idea for these was given to me by a ripoff ebay vendor who had some period Canterbury-style cabs at £900, which he subsequently declared (on no evidence that I could see) were Tannoy originals, with a bumped price of £5000. That rather ruled me out but got me thinking.

I engaged our own Paul Coupe of RFC fame to take the fairly basic existing late 50s Tannoy plans (which have flexibility written into them) and re-work them to modern construction standards and port tuning. Much to-ing and fro-ing on the design (with lots of calculations on Paul's part) and we ended up with the original Canterbury proportions, up a shade under 10% in linear dimensions, to give tuning at 43hz which should get me about 35hz in-room (a big improvement on the 52hz tuning of the original) and also bring the tweeter height to a modern 90cm from what was 70-something (longer feet help here).

Paul also re-worked some crossovers I bought from Robin, with high-end bits (in the end I think only 1 cap, a few resistors and the backboard were unchanged!). Paul worked in lots of extra bracing, 36mm (double thickness) top, bottoms and fronts, and an appropriate level of damping based on his fine tuning of his own Fidelios. Drivers are some early 12in Golds with the hard surround - in my view the best 12in Golds, better than the Tannoplas ones which are closer to HPDs, from James C who also kindly lent me some Chatsworth-type cabs and original crossovers to keep me in music while the build was being done.

The construction was done by Russ Collinson, in a mix of birch ply with laquered sapele mahogany veneer, and solid sapele mahogany trim. Unlike on the originals, Paul designed the side vents and fronts to be retained by magnets so they clip on and off really nicely giving the option of having bare fronts to show off the drivers.

They arrived today - absolutely lovely they are too. Bass is undoubtedly better than my old GRFs and the benefit of the new crossovers in delivering lowest possible distortion is apparent right from the off. I could have gone lower with the tuning but was worried about a loss of impact - I think what we arrived at is probably the perfect balance for this speaker.

Anyway, a ton of thought has gone into this as well as Paul's extensive Tannoy expertise and to some extent my own learning from the Autograph build and what details it pays to pay attention to. Hope you enjoy the pics. Next phase is to see what amps suit them best (Tannoy performance being extremely amp-dependent and what works best varies a lot from model to model as I know from long experience with Lancasters, GRFs, Lockwoods, and Autographs).

Tannoy badges still to be added BTW, I have some lovely ones courtesy of Mark Pitcher.

http://i1181.photobucket.com/albums/x440/montesquieu61/cant-1_zps27591d8f.jpg (http://s1181.photobucket.com/user/montesquieu61/media/cant-1_zps27591d8f.jpg.html)

http://i1181.photobucket.com/albums/x440/montesquieu61/cant2_zps02c5c433.jpg (http://s1181.photobucket.com/user/montesquieu61/media/cant2_zps02c5c433.jpg.html)

http://i1181.photobucket.com/albums/x440/montesquieu61/cant3_zps55f3f5ae.jpg (http://s1181.photobucket.com/user/montesquieu61/media/cant3_zps55f3f5ae.jpg.html)

http://i1181.photobucket.com/albums/x440/montesquieu61/cant-4_zps3e02b8ed.jpg (http://s1181.photobucket.com/user/montesquieu61/media/cant-4_zps3e02b8ed.jpg.html)

[jandl100]

You should provide free drool-bags for all the Tannoy Fanboyz here! :drool: :D

I hope you enjoy them muchly. :thumbsup:

[Yomanze]

I think The Barbarian has already nipped upstairs after seeing the legs, styling, wood...

[istari_knight]

Very nice indeed :)

[Marco]

Lovely stuff, Tom - glad that they're hitting the spot (and well done to Paul)! :respect:

Marco.

[Audio Al]

Yum

Very desirable :)

[petrat]

Excellent project!
What's the rest of your system nowadays, Tom?
Love to hear from all concerned about the challenges and thinking that went into the build.
Very impressed.

[montesquieu]

Excellent project!
What's the rest of your system nowadays, Tom?
Love to hear from all concerned about the challenges and thinking that went into the build.
Very impressed.

Amplfication is a Tron2 'kit' amp (DIY hifi supply) this is quite special being DHT powered (single output stage) either 2A3 or 45. I'm running this with a modified version of the original WAD 300b interstage push-pull power amp - about 28w, all triode/class A/no feedback, the design was originally done by Tim de P and modified for production by Andy Grove. This one was John Caswell's own amp for many years and has some changes to the input circuit to reduce the original's fearsome sensitivity (which essentially precluded using an active pre) as well as a different rectification arrangement. (Though I must say Peter I've been more than a little curious about your EAR534 and how it would be with the Canterburys - maybe you could bring it down for a listen?).

Sources: Vinyl comprises TD124/Jelco 750D/Audio Note Io, Kondo S6c SUT, and a Nick Gorham Longdog Audio MM with switchable twin inputs and twin outputs; for mono there's a custom 12in arm running a Miyajima Premium Be cartridge (which can be swapped out for a dedicated 78 cartridge with a variety of tips) and a Denon HA500 head amp which works wonderfully with the Miyajima and can be bypassed when running 78s. One one of the outputs is an Esoteric Sound Re-Equalizer box (tweaked by Nick Gorham with a better PSU and vastly upgraded opamps) which enables post processing of the signal to accommodate the non-standard RIAA curves found in some early mono and all 78s. (Being on a second output means it doesn't need to be in the loop when the Io is running).

On the digital side is an AN CDT2/II transport and a much modded AN kit dac that's had component upgrades including some very high-end output and I/V transformers to roughly AN DAC4.1 level. This has recently been changed to having four inputs (2 x RCA one of them with a JFET buffer instead of the silver input line transformer), one XLR with silver input transformer, one USB, so lots of flexibility for future experiments in streamed audio. (Which is handy as I'm playing a lot at the moment with 78 transcription).

As for the build, Paul has been amazing, it's been really fun working with him on this and Russ too has been fantastic. We are exceptionally lucky having access to people of this calibre. I should let Paul speak for himself though he has put some info about this on his Trade section thread.



You should provide free drool-bags for all the Tannoy Fanboyz here! :drool: :D

I hope you enjoy them muchly. :thumbsup:


Thanks Jerry - I think another music day has to be on when the weather improves.

[Reffc]

Thanks Tom,

TBH, I was going to hang back and see how you got on for a while, but as the question has been asked, I'm happy to provide a few snippets of what considerations were taken into account.

Firstly, the driver choice. The earlier version of the 12 inch MG has a fairly high Fs (Free Air Resonance point) of around 50Hz compared wit the later RS version, and also quite high compared with the HPD. This means that to obtain a flat frequency response, the cabinet acoustic loading, volume and vent tuning all need careful consideration.

Tom had settled on the Canterbury as his preferred cabinet for his new room. The problem with the original design is that response is very rolled off from 60Hz downwards, the cabinet is hopelessly under-braced and tweeter height is very low. All of these things would lead to sub optimal performance, so I started with a clean sheet of paper and addressed these and other issues to find the best compromise.

Tannoy originally recognised the need for more volume in later papers and correspondence with customers and better acoustic damping as they recommended 6 inches of internal foam or acoustic panel treatment to tame unwanted distortions and present the woofer with a virtual enclosed space larger than the net volume would have you believe (Increasing foam or wool damping alters the system "Q" but also provides the woofer with a larger acoustic volume and lowers response...it also increases group delay).

Long story short...lots of calculations later and an appropriately sized cabinet was designed for the flattest in-room response to a reasonably low frequency bearing in mind the limitations of the early 12 inch MG. This was then simulated in a model and compared with Tannoy's own recommendations (they recommended 150 litres net with tuning to 36Hz). Tannoy's original suggestion works very well with the HPD and later golds, but not really with the higher Fs MGs which require a smaller volume to give a more balanced sound. Going to 150 litres with the driver in question also increases group delay audibly (bass lag) and the LF response would be too rolled off.

Internal bracing and panel thicknesses were calculated utilising materials stiffness data and basic finite element analysis to limit panel resonance amplitudes and shift unwanted resonances out of the critical mid-band.

Tuning was calculated based on Tannoy's recommendations for the 12MG but shifted using the basic 25% rule (applied to bass tuning); so the final tuning point was chosen based upon acceptable group delay and in-room response estimates. They can only be estimates until the speakers are tried in the room intended for them. I calculated that they ought to provide fairly meaningful bass to mid 40Hz and this is reinforced to mid 30Hz with corner placement. What was more important for Tom and for my own thoughts was that impact (a function of acoustic loading and tuning) shouldn't be too heavily compromised and in many ways this is more important than getting the deepest bass response.

Vents were designed to provide the required tuning and attention to detail was called for to minimise vent noise, so sizing (width) and shaping of the vents was important as was keeping the inside area at the mouth uncluttered to minimise unwanted turbulence at entry. Bracing in this location was shaped to account for this as was the acoustic damping.

The damping itself was designed for three considerations: panel resonance damping and acoustic damping, the latter increased in the area immediately behind the driver. The same combination which worked very well with the RFC Fidelios was employed here.

Finally, details such as the grilles were worked out to have no detrimental impact on vent tuning and visually to match the original as closely as possible, although the eagle eyed may have spotted that the vertical fluting on the side vent grilles have fewer vertical pieces than some of the originals. This was to avoid interaction with the tuning vents. Material had to be acoustically transparent and Tom wanted to match the existing traditional design in something textured with an oatmeal colour. I suggested Cara Acoustics fabric as they provide acoustically transparent materials in a wide range of colours to the texture Tom wanted so they were chosen. The magnet strengths and locations were carefully calculated; again, the use of grille magnets is something I employ with the RFC speakers and I thought that Tom might want the option of a bare cab so the veneer/driver could be visible if desired.

That's about it really besides some of the less interesting number crunching. The crossovers were redesigned when I saw that most of the values were incorrect when Tom first sent them to me. All I did was to provide the correct circuit and rebuild them with tom dictating the quality of the components that he wanted to be used. I advised on the budget options and on the more important components choices in terms of specific choices for several components for best performance.

The completed speakers taken as a whole were designed for minimising colourations (as far as one can with these drivers) by providing a very non-resonant cabinet, a clean mid range and control of the (usually) audible 3Khz horn resonance to give a clean well balanced sound. That was the theory anyway. Tom may wish to comment on whether these goals were achieved or not. I haven't heard these yet but look forward to doing so at some point.

Tom was a complete pleasure to work with as was Russ who did a fantastic job building the cabinets.

[Wakefield Turntables]

I can only say two things

1. You are going to be for a real treat.

2. Paul knows his tannoy stuff the external xo I received have transformed my kit.

I really wish you well with these beauties. :)

[Jazid]

Wow,
top stuff :eek:
It's nice to see a group effort of this calibre come together and look forward to hearing your impressions once they have settled in. A much better fit for your new room as well IMHO! I am also curious about the trade offs between group delay and extension Paul has gone through. Must do some reading up!

[loo]

Tom, please make some room in your in box I need to send you an important PM
Paul

[anubisgrau]

i have a full respect for work like this, actually in the whole wave of mental horn DIY actions all around i rather prefer a slight sonic compromise but a nice integration with a living space these kind of things provide... in my book these gives a bit more pleasure when you take everything into account...

pardon my ignorance and lack of knowledge but what is the difference between canterbury and GRF corner cabs - i think you had later one in your previous house? i dont mean scale and size, rather if they differ in the way of acoustic loading?

[anubisgrau]

pls clear your inbox tom

[montesquieu]

OK .. back to it. The eagle-eyed will have noticed that I didn't write much about the sound of these in my first post. That's because I cracked one of the input sockets on one of the Golds, leading to an intermittent tweeter. What I was hearing when the tweeter was working was good, but not sufficient to really make a full judgment on the sound ... just as I was getting into things, it would cut out.

So I've been messing round with mono for several days. Still fun, but the suspense was killing. I also did some slight tweaking to the damping on Paul's instructions. Eventually I managed to track down a new original Tannoy socket (again courtesy of Mark Pitcher), and it was fitted today for me by John Caswell. Sloped off work from mid-afternoon to give them a proper listen.

First off (and I'm sure this is very much down to Paul's work on the crossovers) I've never head Tannoys sound so pure and distortion-free. These are remarkably free from any grain, honk, or raggedness around the crossover point which is so often quite market when using original 60s crossovers. The sound is wonderfully even top to bottom - no part of the frequency range sticks out - and also seem more accurate than previously in terms of tone and timbre, something Tannoys aren't always the best at. These are top notch crossovers by any standard.

Impact is all I was hoping for ... what I wanted to avoid, what I've heard before with large cabinet ported speakers, is cabinet volumes big enough to give low notes, but which suck all the impact out ... transient information just evaporates. Part of the discussion with Paul was to tune the Canterburys in terms of tuning and volume to be 'low enough' but without destroying impact in the bass. Impact further up the frequency range was another question .. that's where the GRFs really scored with their mid-horn (even if it does result in a slight but very characteristic mid-bass hump). I wasn't expecting the Canterbury cabs to get anywhere close, and was surprised to find it's not far away at all. These are proper Tannoys, room-filling, body-hitting, gut-satisfying Tannoys, not of your little cat coffins designed to tinkle just your eardrums.

The Canterburys' soundstage-3D ability is remarkable - I was listening to Hermann Prey earlier on, singing Schubert. He's standing right in front of the piano and the illusion of depth is amazing, like the piano is 6ft back on the stage. The GRFs used to do this trick really well and it was really lovely to hear that on these too. Actually I think here 12in Golds score over the 15s, there's a wonderful natural (meaning tight and accurate) feel to them that goes hand in hand with a real sweetness. Heart-achingly musical too, not that the 15s were a slouch in that department, but I think with the 12s there's just a bit more snap and agility that mean they are ever so slightly more communicative - important certainly for my diet of keyboards, baroque ensembles, lieder and chamber music.

Out and out bass performance is the main area where the 15s beat the 12s, the low notes are there but it's not the ultimate in deep extension or articulation. I'm pretty sure they go lower than the 15s in the GRFs, but the 15s in the Lockwoods Majors or Autographs (though each qualitatively different) are another story. Also, if you really look for it, there is a shift, perceptible if not hugely marked, in scale from the smaller speaker compared to the larger one. Paul insists a move from Golds to HPDs would give both more extension, and greater 'slam' - and it's something I need to check out, for curiosity's sake. But the sweetness/rightness of the Golds would be a hard thing to pass up.

Anyway I've been on tenterhooks since this project kicked off back in mid-late January and there were some moments I wasn't sure I'd done the right thing. There is RISK associated with this kind of project - it's not like, you buy something off the classifieds, if it's not to your taste or there's no synergy you can flog it on for much what you paid. I felt quite exposed at various points. But in the end, I feel it's really been worth the journey. (I must say too there's a feeling of relief as well as simple pleasure).

(A very big) Thanks again to Paul and Russ, and indeed also thank to Mark and John as well for getting me going properly.

[audio39]

Very nice Tannoys!!