Hi Mr Pass, sorry this is a little off forum topic, being a pass labs / tannoy owner I was wondering if you've made any crossover modifications to your 385hdp Jensen imperial set up or if you've kept stock values. I seem to recall somewhere there was mention of some changes done. Would you mind sharing as such? It would be greatly appreciated. Thanks
Joe Sammut put the Tannoy 15" HPD385 coaxials into Jensen Imperials
(upside down) built by my interns in 1999. The crossover is based on the
original from Tannoy, incorporating some of the changes offered by Filton
Acoustics. I think the only original component is the transformer. Some of
the replacement caps are Hovland. Other caps, resistors, and coils are
from North Creek Music.
I have the original schematic, but over 16 years I think it's a little out of
date. It retains the original 2 pole approach at 1 KHz, but the values have
been tweaked.
The performance is +/-5 dB from 30 to about 18 KHz, except for a 55 Hz
bump from the BL horn which I tamed initially with an active filter and later
with fiberglass in the throat of the bass horn.
We have several pair of these, and they remain our primary reference for
evaluating amplifiers. To quote Joe, "They might not be the absolute best,
but they allow you to hear the differences between amplifiers"
(upside down) built by my interns in 1999. The crossover is based on the
original from Tannoy, incorporating some of the changes offered by Filton
Acoustics. I think the only original component is the transformer. Some of
the replacement caps are Hovland. Other caps, resistors, and coils are
from North Creek Music.
I have the original schematic, but over 16 years I think it's a little out of
date. It retains the original 2 pole approach at 1 KHz, but the values have
been tweaked.
The performance is +/-5 dB from 30 to about 18 KHz, except for a 55 Hz
bump from the BL horn which I tamed initially with an active filter and later
with fiberglass in the throat of the bass horn.
We have several pair of these, and they remain our primary reference for
evaluating amplifiers. To quote Joe, "They might not be the absolute best,
but they allow you to hear the differences between amplifiers"
Attachments
Very cool thanks a bunch for sharing this. It's going to be my next project! My first real stereo was a threshold 400a and a pair 12inch monitor golds some 22 years ago. Fast forward and I've got a pair 385 hdp an xa30.8 and some advice from a guy who's amps started it all for me. I find it extremely unique how in touch and giving to the audio community Mr Pass is, thanks again.
Well I built the cabinets, biggest I've ever had it was a two person event getting them from the shop to the house. Luckily I have a man cave downstairs so I'm in the clear with the wife ( actually she likes them better then the open baffles they've replaced for now big trumps ugly, little does she know the open baffles are in for some alterations and may be making another appearance) next is the x- over mods. May I ask though, keeping in mind that you use these to evaluate with, is there a particular amp from your stable that you find yourself gravitating towards with these speakers? Thanks again for the info
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Hmmmm Having Fooled with My Tannoys since I bought them in '71 Suggest also looking at (experimentally building .. even, Troels Crossover suggestion for Golds)
TannoyMG15-Up-Grade
Do notice that the Flitton "acoustics' xover schema has Bungled the LF coil using the "wrong" 1.2 mH value.
(some unknown Twit had in years past, scribbled in a 1.2 mH value on the Genuine Tannoy Circuit diagram ( I have copies of the Unmolested one as well) and Moderene times being what they are.. the Missinfo instantly dispersed)
Repeated wide sample measures suggest ~3.3mH on the OEM coils.. DO read Troels analysis.
I assembled Troels xover as a lark and it subsequently supplanted a bespoke 'for Golds' Active gizmo I had assembled was using
In truth only marginally better but Ohh so much simpler a setup.
Lotsa ways to a similar end
Note there are some experimenting with Open Baffles AND a front loaded horn.. Who knows it may even Work.
One man's adventure:
truefi: March 2015
TannoyMG15-Up-Grade
Do notice that the Flitton "acoustics' xover schema has Bungled the LF coil using the "wrong" 1.2 mH value. (some unknown Twit had in years past, scribbled in a 1.2 mH value on the Genuine Tannoy Circuit diagram ( I have copies of the Unmolested one as well) and Moderene times being what they are.. the Missinfo instantly dispersed)
Repeated wide sample measures suggest ~3.3mH on the OEM coils.. DO read Troels analysis.
I assembled Troels xover as a lark and it subsequently supplanted a bespoke 'for Golds' Active gizmo I had assembled was using
In truth only marginally better but Ohh so much simpler a setup.
Lotsa ways to a similar end
Note there are some experimenting with Open Baffles AND a front loaded horn.. Who knows it may even Work.
One man's adventure:
truefi: March 2015
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Welll My friend IMO you have likely gained Nothing at all.
The OEM autoformer is of Surprisingly high quality when all is said and done and DIY ones have often (typically?) proven inferior.. plus these often delete all the Taps... which are sometimes useful. Not All recordings are created equal.
Only genuine reason for attempting to replicate an Autoformer is Not having one and/or unable to obtain one... which happens.
Same for the 0.820mH HF coil.. Why?
One still has to equal the 12 ohms of the OEM teeny wire one.
Dunno .. My Copy, from Tannoy in mid 70's shows a Part Number: WC3120, 145 turns, 5/8" centre limbed core NO mH identifications, anywhere.
Dunno where the 1.2 mH originated but it was clearly some individuals' notion, Not the works.
Lotsa people self Dick (erm.. DIY) with pore old Tannoys (myself included
Rarely are there genuine improvements though.
Many/most of my efforts were complete bungles as well.
But thru sheer trial and error over 3 decades.. I've learned/gleaned enough info to at least spot the foolish ones and there are Many (sadly, most all)
Genuinely Disheartening are the ones who effect their Bungles for Coin.
Troels.. bless his lil heart, DID get it right eventually, albeit.. After.. realising the/his Error
Hey! he finally spotted it, that alone speaks Volumes.
Kudos well deserved as the workaround IS an improvement on the original xover.
Do read his treatise, it's not time wasted.
Dunno where the 1.2 mH originated but it was clearly some individuals' notion, Not the works.
Lotsa people self Dick (erm.. DIY) with pore old Tannoys (myself included
Rarely are there genuine improvements though.
Many/most of my efforts were complete bungles as well.
But thru sheer trial and error over 3 decades.. I've learned/gleaned enough info to at least spot the foolish ones and there are Many (sadly, most all)
Genuinely Disheartening are the ones who effect their Bungles for Coin.
Troels.. bless his lil heart, DID get it right eventually, albeit.. After.. realising the/his Error
Hey! he finally spotted it, that alone speaks Volumes.
Kudos well deserved as the workaround IS an improvement on the original xover.
Do read his treatise, it's not time wasted.
You do realise you're exchanging words with something, that was already considered an antique in cold war years ?
well - there is improvement - I made proper autoformer , just air cored
big chunk of copper , wire 1.6mm dia
Which means what ?
These geriatric drivers Still work exceptionally well. Better than most.
Snow on the roof perhaps.. a good Fire in the furnace tho.
Well worth stoking if one's ears still work.
I worked at the Cdn Broadcasting Corp in 70's.
We/they aquired *hundreds* of pairs of Tannoy Golds for system wide Studio uses.
Staff 'geer's developed a usable (in a control room) size box and a xover adaptation to suit.
Tannoy apparently had no suitable to needs product.. despite supplying Apple studios.
These worked So well that the California based lab that evaluated them 'took' the design as their own.
Still sells them (I believe ?)
Congrats mr Zen If it pleases that's all that matters.. really.
Getting one to sound/react 'similar' let alone 'better' is an accomplishment in itself.
Others have not been nearly so fortunate in their attempts
As small aside "reducing' the Resistance of the wee .820 HF 'coil' by only 1 ohm.. makes Instant substantitive difference..in HF response (and balance)
Surprising just what the Compression gizmo can do.. when unchained
The oem design is decently Tight... 75/85% of the oem Xover is for trying to deal with that comp driver.. adequately.
Tread lightly
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