Infos about Mastering Labs ML10 Crossover for Tannoy SRM10B needed

[jensenmann]

Is there any info about Mastering Labs ML10 Crossover for Tannoy SRM10B floating around? I´d love to have a look at schematics to see what´s going on in there.
thanks

 

[okgb]

Yeah me too , the tannoy newsgrp seems more hi fi guys , didn't seem to know
much about this one , but even with the nice midrange it needs some real
hi end [ might put ribbon tweeters on mine ]

 

[jensenmann]

humbdybumpy ;D

anybody?

 

[justanalogue]

Hello Jens,

maybe here: http://www.hilberink.nl/speaker.htm

Best regards,

Willem.

 

[pucho812]

I have a pair. I can take some photos if you like


In the meantime here are some specs.

ML10 Technical Specs

    *  Size: 15" Wide X 10" Deep X 22" Tall
    * Weight: 50 lbs.
    * Shipping Weight: 58 lbs each
    * Drive Unit: 10 inch Dual Concentric
    * Recommended Amplifier Power: 50 to 200 watts RMS into 6 ohms
    * Sensitivity: 90 dB SPL Watt/Meter
    * Frequency Response: 55 Hz - 20 KHz
    * Loudspeaker System Resonance: 70 Hz
    * Internal Cabinet Volume: 28 cubic liters or 1716 cubic inches
    * Physical Features: Mirror imaging left and right for true symmetrical sound propagation. Flush mounting of driver on flat front face for seamless imaging.
    * Crossover frequency: 1900 Hz
    * Crossover type: Second order Butterworth high pass. Second order Butterworth low pass with parallel impedance compensation. Continuously variable high frequency level control with three position treble equalization. Inductors are air core, capacitors are high quality film.
    * Amplifier connections: 2 sets of 3/4 spaced gold plated dual binding posts, suitable for banana plugs. Separate connections to woofer and tweeter for bi-wire or bi-amplifying applications.
    * Retail price in 1990 was $2,095.00 per pair(!)
    * ML10 was discontinued in 1994 followed by ML10A $2950/pr which was discontinued in 1996

 

[toobdood]

  Hmmmm, What do we know:  Both crossover sections are 2nd order Butterworth, looks like there's a Zoble network across the woofer (parallel impedance compensation) and a crossover frequency of 1900hz.  There are calculators out there where you could get all of the values. 
  My recommendation would be to build crossovers using the best parts you can afford WITHIN REASON.  No reason to use $1000$ audiophool parts.  Peace, C

 

[Tungstengruvsten]

I work at Tannoy....what am I looking for?  ;D

 

[okgb]

it was a custom mod that mastering labs did to a model of tannoy 10"s
Manley offered these as well

 

[toobdood]

  You can BET that Manley et al DO NOT use $2000$ worth of parts.

 

[pucho812]

  You can BET that Manley et al DO NOT use $2000$ worth of parts.

true but manley does 2 things.  the most important being the mastering lab name is on them. the other well it's manley marketing.

The mastering lab has a mic pre. THey will be re releasing it. According to  Señor sax the price tag will be high on it as if people really figured out what was going on inside they could make them for pennies. I suspect that is the same case here ???

 

[pucho812]

Here is a website for calculating crossovers. Can get you in the ml ballpark


online calculators rock.

http://www.carstereo.com/help/Articles.cfm?id=55

 

[jensenmann]

I have a pair. I can take some photos if you like


In the meantime here are some specs.

ML10 Technical Specs

    *   Size: 15" Wide X 10" Deep X 22" Tall
    * Weight: 50 lbs.
    * Shipping Weight: 58 lbs each
    * Drive Unit: 10 inch Dual Concentric
    * Recommended Amplifier Power: 50 to 200 watts RMS into 6 ohms
    * Sensitivity: 90 dB SPL Watt/Meter
    * Frequency Response: 55 Hz - 20 KHz
    * Loudspeaker System Resonance: 70 Hz
    * Internal Cabinet Volume: 28 cubic liters or 1716 cubic inches
    * Physical Features: Mirror imaging left and right for true symmetrical sound propagation. Flush mounting of driver on flat front face for seamless imaging.
    * Crossover frequency: 1900 Hz
    * Crossover type: Second order Butterworth high pass. Second order Butterworth low pass with parallel impedance compensation. Continuously variable high frequency level control with three position treble equalization. Inductors are air core, capacitors are high quality film.
    * Amplifier connections: 2 sets of 3/4 spaced gold plated dual binding posts, suitable for banana plugs. Separate connections to woofer and tweeter for bi-wire or bi-amplifying applications.
    * Retail price in 1990 was $2,095.00 per pair(!)
    * ML10 was discontinued in 1994 followed by ML10A $2950/pr which was discontinued in 1996

Pictures would be great. It´s a good starting point to figure out what´s the deal with it.

 

[jensenmann]

I work at Tannoy....what am I looking for?  ;D

It´s a third party crossover about which a lot of people are raving. You probably won´t find info at your company. btw, are there still reconekits for these speakers available?


Pucho, did you have a chance to compare you ML-modded SRM10Bs to the original version? Is it worth the trouble?

 

[pucho812]

I have heard the stock crossovers that were made by Tannoy.  I have done a/b comparison tests. I find that the mastering lab version are more tight in the low frequencies and have better stereo imaging.  Is it worth it, Yes.

looking at the original crossover schematic, what is the purpose of T1?

 

[Conductor]

...what is the purpose of T1?

To increase HF level (autotransformer).
Like BBC LS3/5a: http://www.groupdiy.com/index.php?topic=32879.0.

 

[jensenmann]

Thanks for the original schematic. C1 plus T1 are a second order high pass filter. The different taps of T1 make it work like a voltage divider to increase or lower HF Level as Conductor said.

 

[pucho812]

Thanks for the original schematic. C1 plus T1 are a second order high pass filter. The different taps of T1 make it work like a voltage divider to increase or lower HF Level as Conductor said.

thanks for the info, I couldn't see it clearly. That schematic is the Tannoy version.

 

[pucho812]

o.k. I tried to pull mine apart today with the hopes of taking pictures...

They are really really glued in there. There is no real way to get at them without damage to the speaker box.  I can tell you from, what I was able to see, there is no transformer in there like on the original circuit. The front controls are all for the tweeter and there is no bass controls. There is a boost,Cut,normal(un effected?) switch for 9K and up. Then there is the  pot for 2K and up which  that goes from min  normal - max, There is a range marking where the normal would be.

There is enough information with all this so that someone who is real smart could draw a schematic for the board. any takers? Here is a basic Second Order (12db/octave) butterworth Two-Way Crossover with 8 ohm woof and tweeter(that was listed as impedence in the srm/sgm docs I read on the first website posted)



Capacitors
C1 = 7.4 uF
C2 = 7.4 uF
Inductors
L1 = 0.95 mH
L2 = 0.95 mH

hmmmmm. I wonder if the 9k and up is just a shelf that  is either in circuit boosting, cutting, or not doing anything in normal position?


This website has the calculator for figuring out the zobel network

http://www.carstereo.com/help/Articles.cfm?id=55

 

[jensenmann]

Tannoy advertisement states that these monitors are time-aligned. This is done with R1 which forms a slight delay together with C2 and C3. This compensates the different soundsource-planes from HF and LF drivers. Leaving the delay out would mean a lot of combfiltering effects around the crossover frequency. Calculating the delay gives a compensation of 10cm which looks a little big to me. Or did I calculate it wrong? Maybe going here into detail could be a good starting point for improvement.
Thanks, Pucho

 

[pucho812]

what if one reversed the polarity between the woofer and tweeter, wouldn't that do some basic time alignment by delaying the sound by half a cycle?