Tosh
Well-known member
The OEM woofer is 'bad' because it has a passive xo in between the amp and the woofer. Go active xo, and that old woofer is unbottled to go and live its best life...
What causes panels to wear out?
- Thread starter Chippieboy
- Start date
Help Support MartinLogan Audio Owners Forum:
Since the ReQuest and Monolith III were made in roughly the same timeframe, they likely used the same 12" driver in both. I can assure you that any modern 12" driver will result in much better-controlled bass.
I found it much 'tighter', and of course, by crossing over higher, the mid-bass sounded much more present.
The combo of the old driver and passive XO was pretty bad. Going active was an immediate win, and later, upgrading the woofer was yet another step forward in clarity and authority.
Chippieboy
Active member
Funny since Martin Logan boast about the crossover and their woofers in all the ads. I do like the idea of active crossover. I'm guessing I will use my Mini DSP. Correct me if I am wrong. Two things do concern me about going active.
1. I will have to switch out the Mark Levinson amp with my Sunfire since it's multi channel. Not sure of the sound difference.
2. I think the Mini DSP will convert the analog signal to digital, reshape the sound and convert it back into analog. What will that do to the purity of the sound at the end of the day?
With all that said, I will purchase the woofers that JonFo recommended and start from there.
Any other ideas on crossovers?
1. I will have to switch out the Mark Levinson amp with my Sunfire since it's multi channel. Not sure of the sound difference.
2. I think the Mini DSP will convert the analog signal to digital, reshape the sound and convert it back into analog. What will that do to the purity of the sound at the end of the day?
With all that said, I will purchase the woofers that JonFo recommended and start from there.
Any other ideas on crossovers?
Not to worry... even with the added D/A & A/D conversions, once you've experienced active bi-amping, you will NEVER go back to a passive setup.
The only stipulation is that the DSP must have EQ capability because any tuning filters (notch or shelving filters) in the passive crossover to balance the frequency response will likewise be bypassed.
You will also find that the bass will tighten up considerably and you will have almost infinite tuning capability--- once you have it dialed in, it will sound WAY better than before.
Before I went fully digital, I used an analog preamp upstream of a DBX Driverack Venu 360 DSP/Crossover, which required additional A/D + D/C conversions in the signal path and it sounded great.
I later replaced the Carver C1 analog preamp and went straight digital out of a Logitech Transporter (which is also a digital preamp) directly to the digital input on the DSP. This eliminated the additional A/D + D/A conversions, leaving just a single D/A conversion out to the amps.
My new setup sounds fabulous but I can't say that it sounds a lot better than it did with the Carver C1 and additonal conversions in the signal path.
So don't worry-- get rid of the passsive crossover and be happy!
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Might check if the 4ohm version is recommended vs 8ohm. My QuestZ are 4ohm woofers.
Chippieboy
Active member
Wow Zwick, good catch. I did not even think of that. According to the ML specs, it's 4 ohm impedance. Short of taking the cabinet apart, it's fair to say 4 ohm woofer. Now since I am shopping again, Does the forum think I should match the new woofers specs with the OEM speakers specs? (I did it replacing the torn woofers in my Sequels) Specs as in Q & Resonate Frequency ETC.... Also JonFo suggested in the 8 ohm version an Aluminum Cone style. Any suggestions on cone type.
Cone choices are: Paper w/Glass fiber or Paper/Kevlar or Aluminum or Paper or Carbon Fiber or Coated Paper or Nomex/Glass Fiber or Paper/Carbon Fiber or Poly. Yikes
I did notice that most woofers are 8 ohm and most sub woofers are 4 ohm.
Cone choices are: Paper w/Glass fiber or Paper/Kevlar or Aluminum or Paper or Carbon Fiber or Coated Paper or Nomex/Glass Fiber or Paper/Carbon Fiber or Poly. Yikes
I did notice that most woofers are 8 ohm and most sub woofers are 4 ohm.
amey01
Well-known member
No. Take the woofer out and check. Or you could ask ML service.
You want more than a good woofer - will want to match the specs exactly, as the cabinet, XO, etc are all designed around it.
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I’m considering changing my original Questz woofers. If using the std passive bass crossover pretty sure all recommendations are 4 ohms. Now that I’m active on the bass also curious if sticking with 4 ohms is the recommendation. Certainly would allow going back to passive crossover again if a future owner desired. Will never happen while I own them.
If the original woofers are still functional just save them, that’s what I did with my Odyssey woofers. That way if you did ever sell them and the buyer wanted the passive crossovers hooked back up you can just put the original woofers back in and hook them up.
And your last sentence is right on the money. I’ve been able to try different woofers to see what sounded the best to me without worrying what the impedance is. The active crossover on the woofers gives you so many options for getting better sound it’s just amazing.
Chippieboy
Active member
I received the ReQuest OEM woofer specs from Martin Logan support. Specs are as follows:
Fs 23.03 Hz
Qe 0.259
Qm 4.247
Qts 0.244
Vas 241.18 ltr. ( I converted the Vas from Cubic Liters to Cubic feet and the results are: 8.517, since nothing is close I might have done that incorrect, I am assuming that ltr. is cubic)
Sd 0.0504 m^2
Re 3.171891147 ohm
These are my pending options: (in no order, yet)
https://www.parts-express.com/Eminence-LAB-12C-High-Power-12-Subwoofer-4-Ohm-290-668?quantity=1
https://www.parts-express.com/GRS-1...r-Surround-Subwoofer-4-Ohm-292-820?quantity=1
https://www.parts-express.com/Dayto...-Series-HO-Subwoofer-4-Ohm-295-466?quantity=1
https://www.parts-express.com/Dayto...-Series-HF-Subwoofer-4-Ohm-295-464?quantity=1
I might be leaning toward the closest Fs but not sure what really matters.
Also, I might be leaning toward the Aluminum cone styles since that was suggested in the beginning.
Any ideas or input Martin Logan Owners?
Thank you in advance.
Fs 23.03 Hz
Qe 0.259
Qm 4.247
Qts 0.244
Vas 241.18 ltr. ( I converted the Vas from Cubic Liters to Cubic feet and the results are: 8.517, since nothing is close I might have done that incorrect, I am assuming that ltr. is cubic)
Sd 0.0504 m^2
Re 3.171891147 ohm
These are my pending options: (in no order, yet)
https://www.parts-express.com/Eminence-LAB-12C-High-Power-12-Subwoofer-4-Ohm-290-668?quantity=1
https://www.parts-express.com/GRS-1...r-Surround-Subwoofer-4-Ohm-292-820?quantity=1
https://www.parts-express.com/Dayto...-Series-HO-Subwoofer-4-Ohm-295-466?quantity=1
https://www.parts-express.com/Dayto...-Series-HF-Subwoofer-4-Ohm-295-464?quantity=1
I might be leaning toward the closest Fs but not sure what really matters.
Also, I might be leaning toward the Aluminum cone styles since that was suggested in the beginning.
Any ideas or input Martin Logan Owners?
Thank you in advance.
Tosh
Well-known member
Woofer later. Active crossover first.
Chippieboy
Active member
Sounds good. Speaking of Active Crossover. I'm not sure what frequency to start with. I was thinking of 180 since that is the factory freq. Any pointers?
Good question.
Chippieboy
Active member
Well now I am really starting to wonder. Everyone suggest to ditch the passive crossovers and use an active XO. I get that. What I don't get is, if I go lower in the crossover frequency it will add bass to the panel. I hate to see the side affects of that on the panel. If I go higher, that might emphasize the mid bass and turn the woofer into a midrange driver. Is it the steepness of the curve? Perhaps everyone is referring the room correction EQ that comes with most components that are active crossovers.
Tosh
Well-known member
The low-hanging fruit comes from only changing the bass passive xo to active xo (plus an amp), so the woofer is driven directly. The factory passive xo for the ESL panel stays as-is, so yes, the new bass xo frequency has to match the panel's 180Hz xo point. So try a 12dB/oct slope for the bass to get going.
Chippieboy
Active member
So do you think it is something not so good with the factory crossover for the woofer or the xo freq?
I'm not familiar with ML models and specs (not a ML owner) but I think 180Hz is too low to set the crossover on any hybrid ESL panel that's than less than about 18" wide (panel + baffle). If your panel is significantly narrower, it's mid-bass output will be rather thin/anemic if crossed over at 180Hz, due to the dipole phase-cancellation (low frequency roll off).
Let the woofer play the midbass...
I advise setting your crossover in the 250Hz - 300Hz range, preferably with a 24db/octave filter slope. Otherwise you will have to add so much EQ to offset the mid-bass suckout, the additional excursion will actually limit how loud the panel can play before driving the diaphragm into a stator.
Chippieboy
Active member
Sounds good. Thanks Jazzman. Now I have a path forward.
