Hi,
I´d like to know what the nominal value for the Polarising Voltage of an older MartinLogan Sequel II is (10-14 Years old). My candidat just puts out 1.1kV and 0.9kV in the different positions of the HV-switch. Presumable thats far too low? The Transformer seems to put out such a stray field that the Bass is constantly humming (Coil in the crossover picks up the strayfield). The HV-board has bcome quite dirty throuh the Years, so my guess is, that the dirt has established a leakage path for the HV and the transformer is always running into saturation whlie trying to keep up the Voltage.
regards
Calvin
I´d like to know what the nominal value for the Polarising Voltage of an older MartinLogan Sequel II is (10-14 Years old). My candidat just puts out 1.1kV and 0.9kV in the different positions of the HV-switch. Presumable thats far too low? The Transformer seems to put out such a stray field that the Bass is constantly humming (Coil in the crossover picks up the strayfield). The HV-board has bcome quite dirty throuh the Years, so my guess is, that the dirt has established a leakage path for the HV and the transformer is always running into saturation whlie trying to keep up the Voltage.
regards
Calvin
Hi Tim,
well I´m building ESls my own and have made plane panels with wire stators like Audiostatic and am now building curved transducers like the MLs. Very very fine panels the MLs indeed and the technical solution is to the point, but the quality of the audiotransformer is very low. This costs efficiency (the crossover and frequency correction cost around 10dB!) und sound.
The Sequels I measured had to get maintenance and repair.
Calvin
well I´m building ESls my own and have made plane panels with wire stators like Audiostatic and am now building curved transducers like the MLs. Very very fine panels the MLs indeed and the technical solution is to the point, but the quality of the audiotransformer is very low. This costs efficiency (the crossover and frequency correction cost around 10dB!) und sound.
The Sequels I measured had to get maintenance and repair.
Calvin
Martin Logan Sequel crossover schematic ?
Hi Calvin from Australia,
I was wondering if you have a circuit schematic for the original Martin Logan Sequel, I have the newer SL3 panel fitted to mine but want to see what I can do to improve the crossover (other than better caps), also the later models had the facility to bi-wire and a bass attenuation switch which I want to retro fit...I just know that they can sound much better with a few tweaks !
Cheers
Hi Calvin from Australia,
I was wondering if you have a circuit schematic for the original Martin Logan Sequel, I have the newer SL3 panel fitted to mine but want to see what I can do to improve the crossover (other than better caps), also the later models had the facility to bi-wire and a bass attenuation switch which I want to retro fit...I just know that they can sound much better with a few tweaks !
Cheers
Hi,
here it is ;-)
I did extensive tests with different trannies, crossovers and crossover parts. For e.g when the panel alone was connected to the excellent Amplimo-tranny (1:75) the panel showed better linearity and more HF accentuation. Still though the panel itself could show better HF-response when fitted with a new and thinner membrane. The 12µm thick film ML uses already attenuates the HF response. With a very thin film of ~4µm You can gain up to 3dB at the upper end and better overall linearity. Besides a slight enhancement of the higher frequencies the resolution of details is clearly better.
The original tranny is a remarkable cheap and dirty piece of thing
Its this bad tranny that makes such a complex crossover a must. Every try to make an crossover with lesser part count failed.
With an excellent tranny You can get away with a simple dampened second order filter and notch on the ground resonance. As a result You have better linearity all the way down to 250Hz and a way better efficiency of well above 90dB/2.83V/1m!! But You´ll need a new bass part of course that can cope with that high efficiency or You omit the passive stuff all at once and drive the ESL actively!
Things alter when the crossover is connected! The good Amplimo tranny doesn´t show any significant advantage any more. So You should stay with the original one in this case. All the good of the panel is swamped by the tranny and the crossover. The crossover itself is perfectly engineered to correct for the tranny´s failures and to match the low sensitivity of the bass to the high sensitivity of the panel. So any tweaking is up to the parts and values of the crossover parts.
Of major importance are the values C2, R1 and R2. A change of values here will effect the sound of the speaker much more than changing Cap X from foil A to foil superduper ;-)
C2: tilts the HF-response, with 10µF 1dB less HF, with 20µF +1dB HF
R1: influences the range from 300-500Hz. R1=0.39Ohm gives +2dB, R1=2Ohms = -2dB
R2: changes the complete range below ~3kHz. R2=8.2Ohms -1.5dB, R2=3Ohm +1.5dB
I´d suggest to try different values of these 3 components before starting to throw money at more expensive parts.
Happy tweaking
jauu
Calvin
here it is ;-)
An externally hosted image should be here but it was not working when we last tested it.
I did extensive tests with different trannies, crossovers and crossover parts. For e.g when the panel alone was connected to the excellent Amplimo-tranny (1:75) the panel showed better linearity and more HF accentuation. Still though the panel itself could show better HF-response when fitted with a new and thinner membrane. The 12µm thick film ML uses already attenuates the HF response. With a very thin film of ~4µm You can gain up to 3dB at the upper end and better overall linearity. Besides a slight enhancement of the higher frequencies the resolution of details is clearly better.
The original tranny is a remarkable cheap and dirty piece of thing
Its this bad tranny that makes such a complex crossover a must. Every try to make an crossover with lesser part count failed.With an excellent tranny You can get away with a simple dampened second order filter and notch on the ground resonance. As a result You have better linearity all the way down to 250Hz and a way better efficiency of well above 90dB/2.83V/1m!! But You´ll need a new bass part of course that can cope with that high efficiency or You omit the passive stuff all at once and drive the ESL actively!
Things alter when the crossover is connected! The good Amplimo tranny doesn´t show any significant advantage any more. So You should stay with the original one in this case. All the good of the panel is swamped by the tranny and the crossover. The crossover itself is perfectly engineered to correct for the tranny´s failures and to match the low sensitivity of the bass to the high sensitivity of the panel. So any tweaking is up to the parts and values of the crossover parts.
Of major importance are the values C2, R1 and R2. A change of values here will effect the sound of the speaker much more than changing Cap X from foil A to foil superduper ;-)
C2: tilts the HF-response, with 10µF 1dB less HF, with 20µF +1dB HF
R1: influences the range from 300-500Hz. R1=0.39Ohm gives +2dB, R1=2Ohms = -2dB
R2: changes the complete range below ~3kHz. R2=8.2Ohms -1.5dB, R2=3Ohm +1.5dB
I´d suggest to try different values of these 3 components before starting to throw money at more expensive parts.
Happy tweaking
jauu
Calvin
Thanks Calvin !
But can you tell me if the details your have provided are the same for the original Sequel (Series I)...mine are the ones with the ported bass enclosure and I was under the impression that the characteristics of the crossover were somewhat changed for the later sealed cabinets which have different bass drivers and curves ??
Also curious, it would appear that ML didn't use ported bass drivers on any other model since this one.......I must say that the bass produced by this model is phenomenal, and I don't notice any obvious crossover point to the esl panel...even my "stacked Quad 57" owning buddy is quite impressed by this early model Sequel, although the mid band on it does not even begin to approach the 57's absolute clarity...but what else does....!
Cheers,
Luc
But can you tell me if the details your have provided are the same for the original Sequel (Series I)...mine are the ones with the ported bass enclosure and I was under the impression that the characteristics of the crossover were somewhat changed for the later sealed cabinets which have different bass drivers and curves ??
Also curious, it would appear that ML didn't use ported bass drivers on any other model since this one.......I must say that the bass produced by this model is phenomenal, and I don't notice any obvious crossover point to the esl panel...even my "stacked Quad 57" owning buddy is quite impressed by this early model Sequel, although the mid band on it does not even begin to approach the 57's absolute clarity...but what else does....!
Cheers,
Luc
Hi,
of course is a simple 6dB active filter possible ;-) Just size the input cap of You´re amp apropriately
Sonically it´ll very probabely be a disaster though apart from crossover frequencies well above 3kHz.
All visually open panels exhibit a quite strong ground resonance (+10dB is rather common) with which You have to deal with. Thats what the notch is for. In togetherness with a notch You might get away with a 6dB-filter, though my experience is that 12dB+notch work best with panels of an ML-style.
jauu
Calvin
of course is a simple 6dB active filter possible ;-) Just size the input cap of You´re amp apropriately
Sonically it´ll very probabely be a disaster though apart from crossover frequencies well above 3kHz.
All visually open panels exhibit a quite strong ground resonance (+10dB is rather common) with which You have to deal with. Thats what the notch is for. In togetherness with a notch You might get away with a 6dB-filter, though my experience is that 12dB+notch work best with panels of an ML-style.
jauu
Calvin
Hi Calvin,
Adjusting a capacitor in the amp is what I thought about
You're right about +10 dB resonance peak in esls. But I 've read that this depends on the mechanical tension. With tightly stretched mylar, the amplitude of the resonance should decrease. The reason I think could be that the higher pitched resonance frequence is more effctively damped by the air (acoustic resistance increases with higher frequency). I am not sure if the article I read was right about this, but it came from the philips lab.
Did you measure a strong resonance mode without notch?
ML uses differently sized segments with different resonance freq.
I want to do the same with my next panel. If using a notch, to what freq. must it be tuned if there are two resonance modes?
Can the notch cause some ringing, phase problems or other negative side effects? I'am rather puristic, so I want to keep things simple.
I've seen a lot of hybrid designs without notch. Is there some reason ML is forced to use a notch while others can get away without any?
Best regards, MartinJan
Adjusting a capacitor in the amp is what I thought about
You're right about +10 dB resonance peak in esls. But I 've read that this depends on the mechanical tension. With tightly stretched mylar, the amplitude of the resonance should decrease. The reason I think could be that the higher pitched resonance frequence is more effctively damped by the air (acoustic resistance increases with higher frequency). I am not sure if the article I read was right about this, but it came from the philips lab.
Did you measure a strong resonance mode without notch?
ML uses differently sized segments with different resonance freq.
I want to do the same with my next panel. If using a notch, to what freq. must it be tuned if there are two resonance modes?
Can the notch cause some ringing, phase problems or other negative side effects? I'am rather puristic, so I want to keep things simple.
I've seen a lot of hybrid designs without notch. Is there some reason ML is forced to use a notch while others can get away without any?
Best regards, MartinJan
Hi,
segmenting mechanically with different sized segments doesn´t decrease the Q of the resonance significantely, neithert does the reduction of mechanical tension. With rising tension the resonance-Q gets a bit smaller, but not much. To get rid of it You need some mechanical damping like a piece of fine meshed cloth etc. but that has serious disadvantages on other fields. The reason for high mechanical tension is high efficiency and stable working conditions. As a result the fs is quite high and so is the crossover point. Only when the crossover point is far enough away You might omit the notch. But as long as the fs is in the range of just 2...3 octaves below the crossover point You have to use the notch. The only other possibility would be to use just a high-Q 2nd order filter with a electrical crossover point app. 1.5 to 2 octaves above fs. The acoustical crossover point will then be just below the fs, because the filter will fill up the suck-out above fs and the high Q of the fs fills up below the electrical crossover point (I measured up to 95dB!!) . Efficiency and linearity can be very high, but the long decay of the fs is imho always audible. AfakML did this with their Prodigy.
jauu
Calvin
segmenting mechanically with different sized segments doesn´t decrease the Q of the resonance significantely, neithert does the reduction of mechanical tension. With rising tension the resonance-Q gets a bit smaller, but not much. To get rid of it You need some mechanical damping like a piece of fine meshed cloth etc. but that has serious disadvantages on other fields. The reason for high mechanical tension is high efficiency and stable working conditions. As a result the fs is quite high and so is the crossover point. Only when the crossover point is far enough away You might omit the notch. But as long as the fs is in the range of just 2...3 octaves below the crossover point You have to use the notch. The only other possibility would be to use just a high-Q 2nd order filter with a electrical crossover point app. 1.5 to 2 octaves above fs. The acoustical crossover point will then be just below the fs, because the filter will fill up the suck-out above fs and the high Q of the fs fills up below the electrical crossover point (I measured up to 95dB!!) . Efficiency and linearity can be very high, but the long decay of the fs is imho always audible. AfakML did this with their Prodigy.
jauu
Calvin
Hi,
external mechanical damping like a piece of cloth has some disadvantages
- it looks bad, or at least You loose the transparent looks
- it never works linear over level (excursion or SPL)
- it never works linear over frequency or exactly just on the specially desired frequency
- it´ll make up some kind of acoustical resonant circuit (cavity between damper and membrane), i.e energy storing
- it might lead to reflexions of HF --> interference and distortion of the first wave front (clarity)
- its not necessary to damp the complete diaphragm area, but just damping a part of it could lead to standing waves (break up) because of the twisting the membrane.
- mostly its just used on one side of the diaphragm, therefore introducing some slight asymmetry.
The notch filter also forms a resonant circuit and energy storing mechanism, but it doesn´t spoil the rest of the performance since it can be tuned easily to the desired frequency leaving everything else untouched (since an ESL is a minimum phase system, the notch actually can correct not only for the frequency response but for the phase response, which could be very helpful in the crossover design too).
Since You can´t get away with the ground resonance of the ESl panel by principle You have to deal with it mechanically or electrically . The electrical way beeing the easier and more precise with lesser negative side effects.
jauu
Calvin
external mechanical damping like a piece of cloth has some disadvantages
- it looks bad, or at least You loose the transparent looks
- it never works linear over level (excursion or SPL)
- it never works linear over frequency or exactly just on the specially desired frequency
- it´ll make up some kind of acoustical resonant circuit (cavity between damper and membrane), i.e energy storing
- it might lead to reflexions of HF --> interference and distortion of the first wave front (clarity)
- its not necessary to damp the complete diaphragm area, but just damping a part of it could lead to standing waves (break up) because of the twisting the membrane.
- mostly its just used on one side of the diaphragm, therefore introducing some slight asymmetry.
The notch filter also forms a resonant circuit and energy storing mechanism, but it doesn´t spoil the rest of the performance since it can be tuned easily to the desired frequency leaving everything else untouched (since an ESL is a minimum phase system, the notch actually can correct not only for the frequency response but for the phase response, which could be very helpful in the crossover design too).
Since You can´t get away with the ground resonance of the ESl panel by principle You have to deal with it mechanically or electrically . The electrical way beeing the easier and more precise with lesser negative side effects.
jauu
Calvin
Hi Calvin,
Thanks for your explanations. I understood that , if mechanical damping is used , it should provide relatively small amount of acoustical resistance.I have made some measurements with a small ESL fully damped with batting(back side).The damping only increased non-linearities in frequency response and THD. BTW , for some strange reason i measured quite high levels of intermodulation distortion of panel.With 250:8020 Hz tone frequencies , IMD was ~0.5%. For a comparison , the same test with a dynamic loadspeaker system shew only <0.1% IMD. THD of panel at 1 kHz was 0.2-0.3% , while THD of a dynamic speaker system was ~0.7%@1Khz. I am not sure if my measurements are accurate and it may be influenced by microphone or other devices.
It would be interesting if anybody else here tried to do distortion measurements of ESLs.
Best regards,
Lukas.
Thanks for your explanations. I understood that , if mechanical damping is used , it should provide relatively small amount of acoustical resistance.I have made some measurements with a small ESL fully damped with batting(back side).The damping only increased non-linearities in frequency response and THD. BTW , for some strange reason i measured quite high levels of intermodulation distortion of panel.With 250:8020 Hz tone frequencies , IMD was ~0.5%. For a comparison , the same test with a dynamic loadspeaker system shew only <0.1% IMD. THD of panel at 1 kHz was 0.2-0.3% , while THD of a dynamic speaker system was ~0.7%@1Khz. I am not sure if my measurements are accurate and it may be influenced by microphone or other devices.
It would be interesting if anybody else here tried to do distortion measurements of ESLs.
Best regards,
Lukas.
Hi Calvin !
I'm from Viet Nam.
I'm using Martin logan Sequel II
Can you give me schematic for the sequel II, speakers are in a state of failure, I need it to repair.
Please send it to my mail : hailedinh80@gmail.com
Thanks,
I'm from Viet Nam.
I'm using Martin logan Sequel II
Can you give me schematic for the sequel II, speakers are in a state of failure, I need it to repair.
Please send it to my mail : hailedinh80@gmail.com
Thanks,
I have read the post from Calvin that the ML Sequel II has about 1kV bias. Does that mean that the max level signal voltage is limited to 1kV as well? If not, how much voltage is required to fully drive those panels?
As far as i no,Info from Jim Powers at ML the Sequel2 was the same panel used in the SL3,Ascent,i....
An from what jim told me all the bias boards were the same...An at 3400-3700-V on the panels in the twoway set up....CLS were higher at first but that drop the back to 3700-4000-V...
I have a pr of SL3 here now that i have redone the panels with a bias feed on left an right side... all stock ML panels are only feed from the right side...good for saleing more panels but not good for geting all that these great panels can give....
i have just set up a new bias feed for the SL3s... an it at about 4k an sounds the best i have ever got out of the panels.....so looks to be a little low to me....
Here what i think about the logans i have had 4pr of the twoway,an 1pr of CLSs
Retail...
The panes $$1k-1500....ea
The Bass drivers $$200-300....ea
That Box or frame$$200.300...ea
Bias Board $$30....each...in all...
I think there a lot of room for inporvment in the bias set In any ESL it has just as much to do with the sound as any mylar....or setup tranfourmers....But gets over look like just any thing well work....the bias tranfourmers in the ML $$3.maybe...
Just my 2cents
As far as i no,Info from Jim Powers at ML the Sequel2 was the same panel used in the SL3,Ascent,i....
An from what jim told me all the bias boards were the same...An at 3400-3700-V on the panels in the twoway set up....CLS were higher at first but that drop the back to 3700-4000-V...
I have a pr of SL3 here now that i have redone the panels with a bias feed on left an right side... all stock ML panels are only feed from the right side...good for saleing more panels but not good for geting all that these great panels can give....
i have just set up a new bias feed for the SL3s... an it at about 4k an sounds the best i have ever got out of the panels.....so looks to be a little low to me....
Here what i think about the logans i have had 4pr of the twoway,an 1pr of CLSs
Retail...
The panes $$1k-1500....ea
The Bass drivers $$200-300....ea
That Box or frame$$200.300...ea
Bias Board $$30....each...in all...
I think there a lot of room for inporvment in the bias set In any ESL it has just as much to do with the sound as any mylar....or setup tranfourmers....But gets over look like just any thing well work....the bias tranfourmers in the ML $$3.maybe...
Just my 2cents
Calvin, a request.
For some reason that attachment (S II xover & bias) doesn't increase in size when clicked and when saved and blown up loses all resolution.
Is it possible to have a better resolution version - this one is hard to read.
Could you send one via PM to jan AT linearaudio DOT nl ?
jan didden
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