Releasing my inner Tannoy (Eaton Clones )

[smangus]

Hi Folks

A while ago I managed to get a pair of HPD 295 drivers for a realistic price and have been planning a Tannoy build based on the Eaton for the summer. over the last few month I have been thinking around the design with the help of good advice from Mr RFC, Paul Coupe from whom I obtained some crossovers. Due to space considerations the Eaton are a reasonable size for me and as I do not listen at stupid levels would seem to fit the bill, I already have sub so can add this into the mix if I feel that I need more bass.

So the aim is to build some Eaton size boxes with some slight differences as advised


Double thickness tops and bottom on the cabs
Double thickness outer baffle (with sub baffle also)
Plinth added onto bottom of the cabs to house the xovers (possibly)
Braces added inside the cabs to stiffen them up
Front ported


So in my list of "stuff" we so far have

Drivers- check
xovers- check
T nuts- check
Boundless optimism - double check :eek:
Walnut veneer - check
Maple veneer - check
Dangerous collection of power tools - mega check :uhho:

Outline plans - check (to be ignored as appropriate)

When finished I aim to veneer the cabs with the maple on the baffle and walnut on the cabinet outsides and leading edges, finish to be decided, probably something oily, maybe sardines.:D

A couple of caveats-

1. I have never listened any Tannoys of any description at all so have no idea what they will sound like.
2. I 've never built any speakers before or done woodwork since playschool.
3. This may take a while!
4. I aim to document this here but progress might be erratic!
5. No I can't knock the walls down to get a pair of Lockwood's in the living room!
6. Will have to look at how to put photo's on the forum.

All advice, micky takes and well meaning Tannoy large cabinet snobbery gratefully received!

Cheers !

[Firebottle]

...finish to be decided, probably something oily, maybe sardines.

Love it, very good luck with your project.
I will follow it with interest :)

[Wakefield Turntables]

Andy, this looks like a decent project to follow. Keep us posted.

[danilo]

An interesting adventure.
A Well troden path though, so few pitfalls remain.
DO read this though; http://www.troelsgravesen.dk/Tannoy_IIILZ.htm
Don't obsess /go nuts on making the boxes into bank vaults.
The audible differences will be slight to none ;) over simple/stupid single layer 19mm plywood.
Ideally drivers should have their Axis at a listeners' ear level It makes significant difference.
Likely more than a crossover mod.
So plan ahead for location and / or height of boxes.. whichever works best for you.

Happy Cobbling

[smangus]

Thanks guys. Gonna haves some fun with it all , stay tuned.

[TazSob]

Subscribed...

Good luck with your project and I'll be following with interest

[smangus]

I know you want pics :)

Speaker test with xovers , low volume to check drivers , sounded ok to me, maybe I'll just skip the cab building ....:scratch:



1778917790


17788

[smangus]

And my *cough* workshop

17793

[Cristobal]

Has anyone here tried Tannoy Dual Concentrics in open baffle?

http://www.hi-fiworld.co.uk/loudspeakers/68-technology/144-designing-loudspeakers-open-baffles-and-bass-part-15.html

[danilo]

yessss.. once upon a time early 90's.... with Sketchy results TBH.
Didn't follow it up as result.
However.. this Man has claimed success.
http://truefi.blogspot.ca/search/label/Tannoy%20speakers
Read it and try to follow all of his links re this exercise.
Interesting reading at least.
Possibly even something to consider

[smangus]

17832

Measuring up the ply, which seems to be an art in itself. Not happy with the first couple of cuts so need to review what I am doing to make them properly perpendicular, no table saw only hand held circular.
:scratch:

[walpurgis]

Can you not buy the wood cut to size at a timber shop? That's what I've done in the past. If you really want to do it yourself, use a T square (make one if necessary). A fine cut blade would help on a handheld saw. Just do it slow and steady. Any minor unevenness in edges can be sorted with car body filler.

By the way, the Eaton cabinet is not really ideal for the HPD 295A driver. It likes a bit more volume to really deliver. It's a fine unit by the way.

[smangus]

Hi Geoff

Thanks for the advice, I've already bought the board so have to cut it which is something I wanted to try out :mental: lol. I have a finer blade and it good for cutting on the board but was not quite straight so the edges were not perpendicular to the face. This would mean that they would not glue to true and would leave more gaps etc which would need filling.

Anyhow I ran a router with a trimming bit along the edges and that's squared them up nicely so now I'll cut slightly oversize and use the router to get to size. Any excuse for some more power tool usage... :eek:

As for the Eaton cabs , I thought I'd do something smaller to start so that I could see how the DIY skills came along and then maybe something bigger later on. It's a test build really and a bit of a learning curve to see how it goes.

Cheers Andy

[walpurgis]

:) Speaker building is a big learning curve.

At first glance it seems simple, but then you learn a bit and that just leaves you realising how little you really know and a vague idea of how much research is still needed to get it right. Not that any speaker is ever quite right. They are all a compromise no matter how fancy or costly.

Have fun! :thumbsup:

[montesquieu]

An interesting adventure.
A Well troden path though, so few pitfalls remain.
DO read this though; http://www.troelsgravesen.dk/Tannoy_IIILZ.htm
Don't obsess /go nuts on making the boxes into bank vaults.
The audible differences will be slight to none ;) over simple/stupid single layer 19mm plywood.
Ideally drivers should have their Axis at a listeners' ear level It makes significant difference.
Likely more than a crossover mod.
So plan ahead for location and / or height of boxes.. whichever works best for you.

Happy Cobbling

Totally agree on the axis at ear height, it's essential with Tannoys.

Beware the Troels stuff he gets a lot wrong when he dabbles in Tannoys - Paul will keep you right, he's gone into this in far more depth than Troels ever did. (Though sounds like Paul already has :D ).

Also disagree on the boxes - bracing/damping is essential and going the extra mile to reduce resonances will have an audible and measurable effect.

[walpurgis]

Hi Andy. Your drive units appear to be HPD 295A by the way. If the back of the cone is doped with a plastic damping coating, they are. They are often marked HPD 295/8, Tannoy were a bit lazy about labelling. The original and different HPD 295 was first used in the Chevening speaker and had foam cone surrounds that rotted away, yours look like the excellent and correct rubber items. They should last a lifetime.

You could carefully remove the gauze dust cap from the other unit. Tannoys tend to sound better without them.

What are your crossovers? They don't look like the HPD series units from the Eaton.

[smangus]

I intend to add bracing as per Paul's advice , xovers are from him too and seem pretty substantial!

Have to stop for a couple of weeks now as we are of to France for a bit! :)

[montesquieu]

I intend to add bracing as per Paul's advice , xovers are from him too and seem pretty substantial!

Have to stop for a couple of weeks now as we are of to France for a bit! :)

Have fun.

If you want a foretaste feel free to drop over when you get back and hear my RFC Canterburys with Paul's crossovers, I'm not a million miles away off J4 M3 (Camberley/Farnborough).

[petrat]

Have fun.

If you want a foretaste feel free to drop over when you get back and hear my RFC Canterburys with Paul's crossovers, I'm not a million miles away off J4 M3 (Camberley/Farnborough).

Excellent project, Andy!

Seriously, do take up Tom's kind offer. It'll give you a benchmark of what well-sorted big Tannoys can deliver. He's also quite knowledgable on Tannoys, having owned various vintage drivers and cabinets.

[smangus]

Tom

Thanks for your very kind offer, I may well take it up sometime in the future. :) No idea when I'll have time to do it though. It would be good to hear some big tannoys.

Geoff, the surrounds are rubber I'll post the serial numbers sometime if anyone is interested. I have a spare dust capb it it is darker than the others so may well cut it off.

[walpurgis]

Geoff, the surrounds are rubber I'll post the serial numbers sometime if anyone is interested. I have a spare dust capb it it is darker than the others so may well cut it off.

Tannoy were notorious for mixing batches of drivers, the serial numbers are very unlikely to be close, not that it matters.

Just my opinion, but if it's a choice between dust caps or not, I'd go without. It won't hurt the speakers and adds a tiny bit more clarity to the sound.

[smangus]

:scratch::scratch:

Ok so the plans I have have the bass port extending into the speaker for 80mm from the back of the sub baffle. So to the front of the main baffle the port length is 116mm.

So if I double the main baffle thickness to 36 mm should I shorten the port length inside the box by the same amount to keep the same tuning or will it make next to no difference ?

Any adviceg gratefully received!

Thanks

[walpurgis]

If the cabinet volume is reduced, the port tube needs to be longer to retain the same resonance point. Cone amplitude and port output levels are likely to change.

[smangus]

Thanks

Internal volume will stay unchanged so I guess the port length is unchanged overall to?

Seems sensible but I know nothing is always as it seems!

[walpurgis]

If the cabinet retains the design volume, the port should be as standard.

[smangus]

No time to do anything until next week now, however in the meantime these have arrived! :)

17856178571785817859

[Macca]

They look like some quality binding posts.

[danilo]

:scratch::scratch:

Ok so the plans I have have the bass port extending into the speaker for 80mm from the back of the sub baffle. So to the front of the main baffle the port length is 116mm.

So if I double the main baffle thickness to 36 mm should I shorten the port length inside the box by the same amount to keep the same tuning or will it make next to no difference ?

Any adviceg gratefully received!

Thanks

Doubling the Baffle thickness to 36mm Will make NO audible differences ..
Unless possibly to champher the edges of the Driver cutout to continue the Cones' curvature as an expotential horn.. Tricky to effect though
10's were Bass constrained, certainly so for a DC.
A larger box would be The best possible upgrade.

[struth]

:scratch::scratch:

Ok so the plans I have have the bass port extending into the speaker for 80mm from the back of the sub baffle. So to the front of the main baffle the port length is 116mm.

So if I double the main baffle thickness to 36 mm should I shorten the port length inside the box by the same amount to keep the same tuning or will it make next to no difference ?

Any adviceg gratefully received!

Thanks

If the extra thickness is on the outside then the port should stay same to keep what you have. If the internal size goes down a bit then you may have to adj it a bit.

[walpurgis]

10's were Bass constrained, certainly so for a DC.

That is true of the IIILZ, but the HPD 295A is capable of some proper bass output in the right box. I know what they can do as I've owned many pairs. The bass performance is superior to early 12" Monitor Golds, which I've also possessed.

[montesquieu]

That is true of the IIILZ, but the HPD 295A is capable of some proper bass output in the right box. I know what they can do as I've owned many pairs. The bass performance is superior to early 12" Monitor Golds, which I've also possessed.

Totally agree on this, the 12in HPD (**in the right box** as you say) can match the 15in MG for bass depth and weight, albeit at the expense of some efficiency (which is why HPDs need a lot more welly than MGs). Likewise the 10in HPD is potentially a great performer in many areas where both the 12in MG (which is sweet but bass light) and IIILZ - that is the '10in MG' - fall behind.

I was actually astonished when I replaced my 12in MGs with HPDs in the RFC Canterburys, with the approriate crossover mods. I gained an extra octave in the bass with no compromise at all. I had previously resisted all Paul's entreaties to give away my beloved MGs in favour of HPDs. I was so wrong! (I actually still have the 12in MGs here, in a cupboard).

Part of the ongoing confusion over what speaker dimensions to use for the various Tannoy drivers is that Tannoy made a lot of sub-optimal boxes over many years, both in terms of cabinet volume and in terms of physical construction. As Guy R Fountain, Tannoy's founder, famously said: 'We aren't furniture makers'. This attitude certainly shows right through to the early 80s at least.

[Reffc]

Totally agree on this, the 12in HPD (**in the right box** as you say) can match the 15in MG for bass depth and weight, albeit at the expense of some efficiency (which is why HPDs need a lot more welly than MGs). Likewise the 10in HPD is potentially a great performer in many areas where both the 12in MG (which is sweet but bass light) and IIILZ - that is the '10in MG' - fall behind.

I was actually astonished when I replaced my 12in MGs with HPDs in the RFC Canterburys, with the approriate crossover mods. I gained an extra octave in the bass with no compromise at all. I had previously resisted all Paul's entreaties to give away my beloved MGs in favour of HPDs. I was so wrong! (I actually still have the 12in MGs here, in a cupboard).

Part of the ongoing confusion over what speaker dimensions to use for the various Tannoy drivers is that Tannoy made a lot of sub-optimal boxes over many years, both in terms of cabinet volume and in terms of physical construction. As Guy R Fountain, Tannoy's founder, famously said: 'We aren't furniture makers'. This attitude certainly shows right through to the early 80s at least.

Totally agree Tom.

The box is a vital component for the SQ of ANY Tannoy DC drive unit. The more rigid and acoustically dead the front baffle, the better. When you consider that the front baffle acts like a speaker driver in itself, due to the larg-ish size of many DC cabinets, you're essentially creating an out of phase driver, randomly damped wrt frequency, and this adds a significant amount to direct sound colouration. It's what gives many older cabinets their "vintage" sound which can be indistinct, warm and woolly.

The cabinets for DCs do NOT follow thin walled theory, or at least should not. The more rigid and better damped they are, the better. Often, a combination of Birch ply for stiffness, and a layer of high density MDF (750KG/m3) brought together form the ideal laminate for a DC cabinet.

As the cab grows in size, MDF becomes less desirable as a structural element because of its tendency for damage, especially joint damage, if dropped or knocked, so using the correct grade of slow grown Birch Ply tends to be the most practical solution, although you can still line the structure with MDF. Personally, when building large cabs, I prefer to work in very slow grown Latvian Birch of furniture grade quality with a higher than normal resin (ie bonding glue) percentage. This provides a well damped and very stiff structural timber. Assessing thickness and bracing requirements takes a little science, but get it right and people would be astonished at just how neutral and revealing vintage DCs actually are.

[smangus]

Thanks for the comments all , tried to get back to bodging today and measured up some more ply but couldn't cut as the rain started, a bit frustrating :scratch:. I have to cut outside as there is no room anywhere else so it's all dependent on the weather!

[danilo]

So much urban lore on pore old DC's.
Much more than when they were current TBH Likely just as much as on MGB's :eyebrows:
DMT's were the epitomy of Dual wall constructions. Well excecuted actually.
Typically these provided the sounds for a Myriad of Stipper bars across North America. A few even ended up in residences.. decent speakers.. Butt ugly tho.
Nelson Pass uses 15" HPDs in Jensen Imperial cabinets of 3/4' Plywood with a crossover variant developed in his shops.
These are His reference Speakers..not because they are the best speakers in the world (he doesn't think so) but because they reveal even the tiniest Typology differences in his continuing explorations with Amp circuits.
This from a man who built klienhorns ( https://www.passdiy.com/project/speakers/the-kleinhorn-part-1 and the required Subs.. Decades ago.

[smangus]

Well, just to prove I had not forgotten about these, a brief update, although progress has been slow due to time constraints. I also had a distraction with my Karcher adventure http://theartofsound.net/forum/showthread.php?46654-The-Krazy-Karcher-Rekord-Kleaning-Kaper :)

I managed to cut a load of ply which consists of the components of the tops bottoms and sides of the cabinets. I've decided to glue and screw the tops and bottoms together and then mock up the cabs so that I could work out where to places the braces (2 per cabinet) in relation to the drivers. The aim is to recess the braces into the front , sides and back by about 3 or 4 mm all around so that they tie the structure together neatly. (me being optimistic here. :D)

I'll have to crack on with the baffles at some stage, double thickness with a sub baffle added so 3 layers of ply.

Due to the protrusion of the driver and bass port internally I had the bright *cough, cough* idea of incorporating the bottom of the port into the area of the top brace so that less area internally is lost , this is going to take a bit of thinking about but hey all in the name of adventure :eek:. No pain no gain etc, as they say.

Warning , what follows are some gratuitous wood shots...

Boring shed pic of bits of wood and other "useful" stuff.

[smangus]

Marking up the screw positions in the top of a cabinet, thought about 9 but went for 15 in the end , I've got 200 of the buggers so what the hell , let's live a little. :champagne:

[smangus]

I love a good countersink....

[smangus]

Glued and screws added, I added some more clamps after this photo for better pressure all round. The glue was Titebond 2 yellow stuff. It seemed to weep out of the sides forever but this should be a good sign I guess.

Next update in about 6 months....:)

[struth]

double thickness. My speaker walls are double thick too. makes em quite heavy

[smangus]

double thickness. My speaker walls are double thick too. makes em quite heavy

Yeah I can feel that already , means SWMBO won't be able to throw them out ,:eyebrows:

[smangus]

:scratch::scratch:

Ok so this might be tempting fate and a silly question but how hard is it to recone tannoys with a recone kit? is it fiddly but reasonably straight forward or should it deffo be left to the likes of Lockwoods etc?

The weather looks like it's improving so I'll get on with this build as soon as I can get outside to muck about with it! I should have some more time for it aswell in the next couple of months.

The drivers are ok but have some crappy glue marks where the previous owner has tried to glue on dust caps, so i'd like to get them reconed at some stage for a tidier look. I'd be happy to have a go at it myself but if the consensus is don't touch then I'll send them somewhere for it.

Cheers

[walpurgis]

An HPD 295A recone should be easy enough. The roll surround is held in place by aluminium strips at the front. Just prise out the foam covering the screws. Take great care unbolting the rear spider. If you drop a washer into the magnet gap you may not get it out.

Take a look through my Tannoy restoration. The drivers are later and a bit different, but there are some good pointers if you have the patience to read through it.

http://theartofsound.net/forum/showthread.php?19555-My-new-(vintage)-Tannoy-Cheviots!

[smangus]

Great, thanks:)

I'll have a look at it.

Cheers

[montesquieu]

An HPD 295A recone should be easy enough. The roll surround is held in place by aluminium strips at the front. Just prise out the foam covering the screws. Take great care unbolting the rear spider. If you drop a washer into the magnet gap you may not get it out.

Take a look through my Tannoy restoration. The drivers are later and a bit different, but there are some good pointers if you have the patience to read through it.

http://theartofsound.net/forum/showthread.php?19555-My-new-(vintage)-Tannoy-Cheviots!


cool thread I hadn't seen this! :)

[smangus]

cool thread I hadn't seen this! :)

yes it is , some very useful photos as well thanks.

[smangus]

So 3 years later I feel I should update this thread [emoji1787] Have managed to find some time to put the cabs together and route out the double baffles. https://uploads.tapatalk-cdn.com/20210402/b96bd36cea93fa1421a49c1ca073cd43.jpghttps://uploads.tapatalk-cdn.com/20210402/b1211acdcf9bb51d6cc25c6a7ae557d3.jpghttps://uploads.tapatalk-cdn.com/20210402/2c0cb47facbb7723f476c8de4c2ac0d0.jpg

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[smangus]

Backs routed to rebate the speaker binding post plate https://uploads.tapatalk-cdn.com/20210402/fcd888e319d9067f12a4094a74613e4f.jpghttps://uploads.tapatalk-cdn.com/20210402/e2409a98410972da7f7e349b081e915f.jpg

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[smangus]

Dry fit with drivers in the cabs
, didn't want to use T nuts so found a clever self tapping thread thingy which worked really well. Tip if you use these grease the threads so the driving nut doesn't get stuck! https://uploads.tapatalk-cdn.com/20210402/6808b5e9ae00fa155f09021fe3bc4fcb.jpghttps://uploads.tapatalk-cdn.com/20210402/641fc274e508782b00d1b55f476f53fe.jpg

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[smangus]

Just need to damp the cabs and make some plinths to put the xovers in now. so probably be in another 3 years or so!

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[Puffin]

Nice job. I really ought to get to hear a nice pair of Tannoys sometime. There was a guy on here who undertook the mammoth task of building his own Westminsters. The build is documented here https://www.hifiwigwam.com/forum/topic/52252-tannoy-westminster-build/

I was going to hear them as they were not too far from me.....sadly I never got there.

[smangus]

Baffle veneered. Looks better than the photo in real life. https://uploads.tapatalk-cdn.com/20210413/d3b9983c16bc9f821a4bd9f66da1223e.jpg

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[walpurgis]

Looks fine to me Andy. Nice job. :)

[smangus]

Ok some updates for completion!

Damping fitted before foam, Backs screwed and glued with recess for the terminal plates rputed out .

Xovers Fitted for test and height fiddled with to see what size plinth/stands are needed. https://uploads.tapatalk-cdn.com/20211019/417f558bf8288965c145710a803046f6.jpghttps://uploads.tapatalk-cdn.com/20211019/faf831efe7a3c82a95a9be15fb6908e8.jpghttps://uploads.tapatalk-cdn.com/20211019/a07a022e4d22889b13d0937316c9e380.jpghttps://uploads.tapatalk-cdn.com/20211019/2a0b45eecfeda10550330091210c5033.jpghttps://uploads.tapatalk-cdn.com/20211019/18cf08d866f4620673fff90ab1395486.jpg

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[smangus]

Plinths made on the bottom to store the xovers, need to make some feet next. https://uploads.tapatalk-cdn.com/20211019/e1543e1d0b6daf1d9aa65193025055f2.jpghttps://uploads.tapatalk-cdn.com/20211019/53eff96c6111b2d0476dbe7ecc40ad72.jpghttps://uploads.tapatalk-cdn.com/20211019/d29409ea675f485c548489c6b69d22ea.jpg

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[smangus]

So far so good , sounds great! [emoji846]https://uploads.tapatalk-cdn.com/20211019/bca76596de2d36994fea8c9f2e8873f4.jpg

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[Puffin]

Nice job.

[Edward]

World class - even more so considering you said you had no experience building speakers. The fit and finish is superb and I'm sure sounds great. I think I read in this thread that the xovers were made by Paul C, he would have brought out the best the drivers are capable of.

It would be interesting to hear how your Eaton clones sound against my original Eatons. Perhaps one day we can arrange something?

And of course playing Eric Dolphy's 'Out to Lunch' is a great way of testing these speakers. :eyebrows:

[smangus]

Finally finished , teak veneer with walnut trim . 4 coats finishing oil and 2 coats Bison wax. Sounds great too. https://uploads.tapatalk-cdn.com/20220821/43eb0ec91bff12187a572b23ff0c3428.jpghttps://uploads.tapatalk-cdn.com/20220821/88f3ffda9a7882dc81999e046755280d.jpghttps://uploads.tapatalk-cdn.com/20220821/789033fd043f03246e33dfe8e681d441.jpg

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