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Overhaul 12" tannoy monitor gold's.

Discussion in 'd.i.y.' started by Jhon, Aug 27, 2019.

  1. Jhon

    Jhon Member

    I am sorting my tannoys and am looking for help/comment/ and observation on the following. It's time I figure to have the crossovers rebuilt but who by and at what cost?. Secondly I have an notion that it might be worth moving the crossovers to behind the amps (leak tl12+'s) and biwiring to the cabs? Any one tried that?. Thirdly I intend to build new cabs. I want to create a floor stander that puts the speakers at ear height. I also always fancied a folded horn but tannoy never did use the twelves like that as far as I'm aware . Hmmm why not? Has any body?. Overwise cab volume? Reflex or not. The bigger the better ? Thanks folks . ( It may take a while to respond to posts as I'm off to visit telecoms black spots in Wales).

    Jhon
     
  2. Mike P

    Mike P pfm Member

    Your crossovers are going to be devalued if you mess with them so apart from replacing any electrolytic capacitors with something suitable (e.g. Blue Alcaps) I'd be inclined to leave them untouched. You can buy new aftermarket crossovers at a variety of price levels so if you want to try non-original crossovers that's what I'd recommend. Other members here have tried aftermarket crossovers with varying levels of success/satisfaction.

    If you like the idea of a folded horn have a look at the rectangular GRF. It's a much simpler cabinet design than other folded horn Tannoy cabinets and lends itself well to a diy build.
     
  3. Jhon

    Jhon Member

    Thanks Mike I appreciate the reply and your point about value. No point in upsetting my heirs just as they are becoming useful. Does anyone have experience of the aftermarket stuff or of existing crossovers being overhauled? I'm thinking keep originals and use aftermarket. Better idea is maybe deal with cabinets first and listen again. Did anyone ever fit twelves to a grf cab. I like the idea of sticking with tannoy.
     
  4. Tony L

    Tony L Administrator

    I’ve done both and to this date never heard a pair of after-market crossovers I prefer to the originals, and I’ve tried some very well respected ones. I’d also caution against doing anything beyond a sympathetic clean of the switches and maybe recap to the originals. The pair of crossovers in my current pair of Monitor Golds are entirely stock and have never been opened. All I’ve done is to give the control panel switches a really good clean with Deoxit. Be aware that if you do decide to remove/hard-wire the control panel they get *a lot* brighter and sound very different afterwards, I suspect the controls were carefully factored into the voicing.

    Basically I’d leave them be unless you believe you have a problem that needs fixing. If you want to try modifications or whatever then build from scratch keeping your existing pair as a reference/control. I’d certainly be very reluctant to do anything even remotely non-reversible.

    FWIW my experience to date can be summed up thus: yes, you can make them clearer and more ‘detailed’, but there is always a price, and for me it is that you lose that ‘thing’ I love so much about vintage Tannoys, whatever it is.
     
  5. Mike P

    Mike P pfm Member

    I've briefly heard 12" Golds in a high quality rectangular GRF cabs whilst dropping off some Corner Lancasters at a fellow members house. He may be along soon to add his wisdom...
     
  6. ff1d1l

    ff1d1l pfm Member

    Try using Silver crossovers with the butyl surround Golds.
     
  7. Jhon

    Jhon Member


    Thanks Tony that is a helpful set of comments especially re third party items and useful reminder to be careful of what you wish for.
     
  8. Jhon

    Jhon Member


    Thanks Mike I am interested in grf rectangular cabs and look forward to hearing about them
     
  9. Jhon

    Jhon Member

    Thanks . What do the silvers do against the gold xovers?
     
  10. jtgofish

    jtgofish pfm Member

    I would not bother.They sound pretty bad compared to say a 150 litre Onken style box.
    Back loaded horns and especially front firing ones suffer from the reverse phase from the back of the driver coming out of the horn and interfering with that which is coming of of the front of the cone.So you get some really weird effects like voices moving around in the soundstage.
     
  11. Mike P

    Mike P pfm Member

    I'd love to hear some nice Onken style cabs.

    Unfortunately I didn't get a proper listen of the rectangular GRF mentioned above (just very briefly and at low volume) so I can't comment.
     
  12. Tony L

    Tony L Administrator

    Before finding my large Lockwood cabs I was very seriously considering commissioning a pair of Onken cabs. IIRC they actually make far more sense with the rubber or foam surround Tannoys which kind of put me off (mine are 15” Golds, so hard surround). I’d certainly look into this if I had a pair of rubber-surround 12” Golds. I suspect they might be a very good solution. There are sites somewhere with the necessary math to calculate the cabinet and vent sizes etc.
     
  13. cooky1257

    cooky1257 pfm Member

    Hard edge 12" Gold Fs is 49hz(if you are lucky), any reflex cab above say 100L is pretty pointless unless you like to increase the 'peak' of the tuning bump.
    If they are 12R's then 130L tuned to 28hz is pretty much the sweet spot in terms of size/performance.

    12R/15" Golds are much closer in terms of Fs/Qts/VAS/Cms/Mms to the foam edge models hence the interchangeability of HPD's and Golds into boxes such as Amesbury/York/Ardens/Lockwoods.

    I just run some sims of a 12R in Onken cab, 330L, 6x rectangular 50x280x450(l)ports, 3 along each side. Shocking 47ms group delay near 31hz tuning that drops to a fine 12ms @40hz. Port air speed is very low @3m/s, bass shelf as is normally par for course with these drivers not tuned maximally flat is virtually absent-1dB and the tuning peak is around +2.5dB in the sim but would expect the aspect ratio of the port /extra surface area drag would damp that to be essentially flat. Huge but interesting.
     
    Last edited: Aug 30, 2019
  14. cooky1257

    cooky1257 pfm Member

    Before getting into external/bespoke crossovers(debatable) any 'overhaul' should start with the drivers.
    Measure them, if they are poorly matched or displaying an uneven response through the hf range significant improvements can be gained by correctly re-installing the HF diaphragms.

    Transfer function of Silver(green) vs Gold(blue) crossovers showing the gold's 2nd order slope, notch filter and HF gain adjustment ;

    [​IMG]
     
  15. ff1d1l

    ff1d1l pfm Member

    Sorry, just seen this.
    They just sound, to my ears, far better.
    They run the bass cone wide open, the crossover for the pressure driver is simpler, uses no level controls and is of higher quality components.
    Makes for a smoother, but much more present and open sound. And the butyl surrounds allow the cone to go deeper.
    Anyone tried Red crossovers on 15" Golds or HPDs, out of interest?
     
  16. mega lord

    mega lord Centre tapped

    I tried this after reading LesW's and MrTibbs views on it. I couldn't quite believe the effect it had. A few pfm members have reported similar. Nobody can come up with a technical reason why it brought the improvements experienced by myself and others.

    Just be careful not to get any inductors too near a transformer or you will have plenty of hummmmmmm.
     
  17. cooky1257

    cooky1257 pfm Member

    And yet Tannoy in their stupidity have maintained the notch filter and 2nd order slopes for nigh on 50 years...;-)
    I think they realised the effects of low crossover slopes/high excursion on comp driver diaphragms-metal fatigue, particularly as available input power increased and the stressful studio environment they were used in.
    I don't question anyones subjective preferences-fill your boots, I've even heard it said the Silver xovers sound better without their metal covers on and holes drilled into the HF back cap.
     
  18. Tony L

    Tony L Administrator

    I am puzzled by this. I’m aware many of the most knowledgeable Tannoy fans (i.e. the Japanese!) consider the 12” Silver to be the all-time high-watermark thanks to its efficiency and openness (it runs the bass cone wide open). I’d certainly be interested to hear a Silver crossover on a Gold, but I don’t understand how it could possibly work properly as the bass cone is a different impedance and weight (heavier on the Gold) and IIRC the physical treble horn was very subtly redesigned with both the Red and the Gold (i.e. two revisions). Has anyone got any acoustic FR plots for the Gold driver with Silver crossover vs. the standard Gold on its ‘level’ settings? That would be very interesting to see.
     
  19. cooky1257

    cooky1257 pfm Member

    I spent some time this morning looking for that very thing without success. On my trawl I read Troels has some interesting observations re Gold raw responses/xovers here; http://www.troelsgravesen.dk/MG15-problem.htm
    Re knowledgeable Japanese they will pay thousands for JBL 375 compression drivers(even sillier money for the hump back cap version)-they are the 4" JBL high watermark, the fact is the JBL 2440 is exactly the same driver..go figure.

    FWIW several specs on the 44bx tables are wrong, in particular the Mmd/Dynamic mass figures, basically they mix up incl/excl air load numbers on some.
    HPD385/3838/Gold should be between ex=68/72g vs 90g incl and with that in mind I suspect the Silver cone is exactly the same as Gold.
     
  20. ToTo Man

    ToTo Man the band not the dog

    So the MG15's natural HF roll-off begins around 2kHz, and presumably a little higher than that for the MG12? So surely running the LF cone with no LPF such as the Silver XO would cause a noticeable broad bump in the response above 1kHz or 1.5kHz? (I always forget if the Gold's XO frequency is 1kHz or 1.5kHz!).
     

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