I have been using the drivetrack as a crossover for over a year now and cannot recommend it more for Martin Logan III owners. Getting the passives out of the way really opens up the bass. I have been through many tweaks on the Logans in this order --have replaced bass drivers (small improvement), got a new bass amp for driving the bass passively through the speaker x-overs (bigger improvement), then bought a driverack for just the bass (wammo this was it). But then I tried actively crossing over my big tube amps for the panels (another step up), then I tried crossing over at 250 hz (versus stock 125), another big step up. Some where in there I applied Greorgehifi's notch circuit on the bass drivers (it's still in).
This is the way to go for ML III owners IMO. But question : has anyone modded the dbx? I see a lot of Behringer 2496 mod projects but nothing for the pa. Appreciate any ideas.
This is the way to go for ML III owners IMO. But question : has anyone modded the dbx? I see a lot of Behringer 2496 mod projects but nothing for the pa. Appreciate any ideas.
How about a mod to extend its bottom to? 10hz? 15hz? If either are possible, 5hz?
*DRPA or DROA+ models
Mine are for home theater use.
Thnx. I look forward to learning regardless.
Tony
*DRPA or DROA+ models
Mine are for home theater use.
Thnx. I look forward to learning regardless.
Tony
It's nice to see others using active DSP crossovers rather than passives.
Once you've heard a hybrid ESL driven through a properly setup DSP crossover; I can't imaging anyone being satisfied with a passive setup again.
I'm using a DBX Driverack Venu 360 on my homebuilt hybrid ESLs and couldn't be happier.
I experiment with crossover points and slopes occasionally but I find that a mirror image crossover at 250Hz using the 24db/octave Linkwitz-Riley filter works pretty well. This allows driving the volume quite high without risk of saturating the transformers or driving the diaphragm into a stator.
I especially like the DBX's user interface and I-pad control app. I'm gonna say the Venu 360 is the coolest audio gadget I've ever owned. It's functionally identical to the PA2 except that it has both analog and digital inputs (which I use) and a bunch of other features you would only use for PA applications.
A Monolith III is large enough that you might get away with setting the crossover way down at 150Hz but I would go higher than that, as you have done. Some DIY ESL builders cross the panel in that low on the premise that ESL mid-bass is cleaner than a woofer, but then they have to add a bunch of mid-bass EQ to compensate the dipole cancellation-- not worth the trade-offs in my view.
I like what you're done with the PA2. I haven't heard about any mods for the DBX's. Their specs are better than the Behringer DCX2496 and they sounds great to me, as-is.
Enjoy!
BTW; I'm driving the DIY wire-stator ESL below with the DBX Venu 360:
Once you've heard a hybrid ESL driven through a properly setup DSP crossover; I can't imaging anyone being satisfied with a passive setup again.
I'm using a DBX Driverack Venu 360 on my homebuilt hybrid ESLs and couldn't be happier.
I experiment with crossover points and slopes occasionally but I find that a mirror image crossover at 250Hz using the 24db/octave Linkwitz-Riley filter works pretty well. This allows driving the volume quite high without risk of saturating the transformers or driving the diaphragm into a stator.
I especially like the DBX's user interface and I-pad control app. I'm gonna say the Venu 360 is the coolest audio gadget I've ever owned. It's functionally identical to the PA2 except that it has both analog and digital inputs (which I use) and a bunch of other features you would only use for PA applications.
A Monolith III is large enough that you might get away with setting the crossover way down at 150Hz but I would go higher than that, as you have done. Some DIY ESL builders cross the panel in that low on the premise that ESL mid-bass is cleaner than a woofer, but then they have to add a bunch of mid-bass EQ to compensate the dipole cancellation-- not worth the trade-offs in my view.
I like what you're done with the PA2. I haven't heard about any mods for the DBX's. Their specs are better than the Behringer DCX2496 and they sounds great to me, as-is.
Enjoy!
BTW; I'm driving the DIY wire-stator ESL below with the DBX Venu 360:
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Ooops! I should have mentioned.
I went active using the DBX Driverack PA for my HT’s Polk 3-way towers about 5 years ago.
Love the SQ improvement in all areas.
Now about that mod…
…the 20-20K hz spec limits low frequency extension to… …20hz. I need 10hz, would like 5hz to manage my tower’s dual subs.
To any one reading this…
I went active using the DBX Driverack PA for my HT’s Polk 3-way towers about 5 years ago.
Love the SQ improvement in all areas.
Now about that mod…
…the 20-20K hz spec limits low frequency extension to… …20hz. I need 10hz, would like 5hz to manage my tower’s dual subs.
To any one reading this…
Very low frequencies down to 5-10 Hz are typically handled with something other than a cone driver.
The Eminent Technology (Thigpen) rotary woofer is one approach.
https://www.soundandvision.com/content/eminent-technology-trw-17-rotary-subwoofer
A Buttkicker or similar bass shaker/tactile transducer is another approach.
https://www.parts-express.com/ButtKicker-BK-LFE-Low-Frequency-Effect-Transducer-300-9400
Many bass shakers have a peaky response with limited extreme low frequencies, so careful selection will be necessary in your case.
http://www.baudline.com/erik/bass/tactile_report.html
The Eminent Technology (Thigpen) rotary woofer is one approach.
https://www.soundandvision.com/content/eminent-technology-trw-17-rotary-subwoofer
A Buttkicker or similar bass shaker/tactile transducer is another approach.
https://www.parts-express.com/ButtKicker-BK-LFE-Low-Frequency-Effect-Transducer-300-9400
Many bass shakers have a peaky response with limited extreme low frequencies, so careful selection will be necessary in your case.
http://www.baudline.com/erik/bass/tactile_report.html
Thank you. You have a lot of good ideas😊.
But first I must have an XO that goes below 20hz (even just 15hz would help) or it’s all for naught. I should have said much earlier that I actually need to mod a Driverack PX (2 way). That XOs my subs to the towers’ bass drivers. The DRPA XOs my towers’ drivers to each other.
It occurred to me in my zeal, I had not checked what the Dolby or THX frequency response is for the LR channels. Regardless I look forward to learning and tinkering.
Again thanks. Tony
I'm not clear on what you're after. Are you worried about the frequency response of the amps/crossover/processors, are you trying to set the cross point to something less than 20 Hz, or are you trying to do 5 Hz in stereo for some reason? Some of those things seem nonsensical, but I don't know what you're thinking, so I'm keeping this post brief.
https://en.wikipedia.org/wiki/Low-frequency_effects
The low-frequency effects (LFE) channel is a band-limited audio track that is used for reproducing deep and intense low-frequency sounds in the 3–120 Hz frequency range.
https://developer.dolby.com/globala...olby-pro-logic-decoder-dp562-users-manual.pdf
Dolby Digital can process 20-bit digital audio signals over a frequency range from 20 Hz to 20 kHz ±0.5 dB (-3 dB at 3 Hz and 20.3 kHz). The low-frequency effects channel covers 20 to 120 Hz ±0.5 dB (-3 dB at 3 and 121 Hz).
https://en.wikipedia.org/wiki/Low-frequency_effects
The low-frequency effects (LFE) channel is a band-limited audio track that is used for reproducing deep and intense low-frequency sounds in the 3–120 Hz frequency range.
https://developer.dolby.com/globala...olby-pro-logic-decoder-dp562-users-manual.pdf
Dolby Digital can process 20-bit digital audio signals over a frequency range from 20 Hz to 20 kHz ±0.5 dB (-3 dB at 3 Hz and 20.3 kHz). The low-frequency effects channel covers 20 to 120 Hz ±0.5 dB (-3 dB at 3 and 121 Hz).
@mattstat thank for helping me.
Bottom line: I don’t want my electronics to limit my LR sub’s low end to 20hz.
They measure fairly flat to 18hz outside. Could as low in-room but seems to roll off faster regardless of readings location.
Background: My HT LR set to “Large,”each has a dedicated sub receiving ONLY the sub signal below 40hz* for that channel. If the Dolby or THX standard F3 is 20hz then I’m sorry for wasting everyone’s time because I did not do my homework.
*tower handles above 40 quit
BTW I have a separate sub receiving the LFE & bass signals for channels set “Small” and I’m not a “Bass head.” Just one who values accurate low distortion reproduction for both 2 ch and HT.
Grateful for your patience and input.
Tony
Bottom line: I don’t want my electronics to limit my LR sub’s low end to 20hz.
They measure fairly flat to 18hz outside. Could as low in-room but seems to roll off faster regardless of readings location.
Background: My HT LR set to “Large,”each has a dedicated sub receiving ONLY the sub signal below 40hz* for that channel. If the Dolby or THX standard F3 is 20hz then I’m sorry for wasting everyone’s time because I did not do my homework.
*tower handles above 40 quit
BTW I have a separate sub receiving the LFE & bass signals for channels set “Small” and I’m not a “Bass head.” Just one who values accurate low distortion reproduction for both 2 ch and HT.
Grateful for your patience and input.
Tony
No need to feel sorry about asking questions. Most everyone is here to learn things and help others when they can.
Part of what you are experiencing may just be room modes boosting the bass in certain bands. It's very common to have peaks and valleys in the region below a few hundred Hz in typical listening rooms. They can be quite large when you are measuring at discrete locations. Some of the magazines now average multiple readings over an area to smooth some of this out of their data, but there are still normally low-frequency peaks and valleys unless room correction EQ is used.
If you are using an impulse-based measurement system, the window needs to be quite long to measure low frequencies with decent resolution also.
Part of what you are experiencing may just be room modes boosting the bass in certain bands. It's very common to have peaks and valleys in the region below a few hundred Hz in typical listening rooms. They can be quite large when you are measuring at discrete locations. Some of the magazines now average multiple readings over an area to smooth some of this out of their data, but there are still normally low-frequency peaks and valleys unless room correction EQ is used.
If you are using an impulse-based measurement system, the window needs to be quite long to measure low frequencies with decent resolution also.