New mod project: LF12 (Yes, 12.)
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Posts: 708
Background
Originally, I wanted a pair of LF14 for the 5B I gave to my Dad.
https://polksda.com/pdfs/LF14Manual.pdf
(They're hard to chance upon, and I gave up actively looking for them.)
So, I decided to make my own.
Kinda sorta.
I mean, the Monitor 12 Series 2 has bigger LF genes in its bones- right?
https://polksda.com/monitor12.shtml
It's got the foundation for a great Frankenmod LF project.
And I do like to try new things...
The 5B are 3 States away but I have these 7B waiting to be reborn, plus my 1C are sitting there... wondering if some low-end reinforcement would sound nice.
Goal
Turn my M12 into a dual-use speaker; half Monitor, half LF approximation.
I want low-end reinforcement that matches the sound/speed/etc. of my vintage Monitors, not over-enhanced bass thump. I want even more vibration around upright bass strings, or more of that feeling of air on a big drumbeat. I don't want a room full of boomy tone.
Project outline
- Figure out how to make an M12 work as an LF12.
- Figure out the crossover issues.
- Make mods.
- Test
Easy, right?
What I did
- Mapped out a bypass 'circuit'. When it's connected, everything works per normal. Engage the bypass and the incoming signal goes straight to the mids.
- Figure out a crossover solution so I wouldn't burn anything out... Enter the Rolls SX95:
https://rolls.com/product/SX95
- Grab a back-up amp to test. My AX-596 is filling in, at least until I luck into something to replace my GFA-555ii on the 1C (or snag something else that's a good match for the role of the LF12). The 596 has a great damping factor, so it'll do for now.
- Mod the terminal plates and wire the bypass.
- Test!
Results
When the bypass wires are plugged into the upper terminals, it works like a normal M12.
When the bypass wires are disconnected, and the amp is plugged into the top terminals, the signal goes directly to the mids.
Signal path
WiiM Mini > Topping E50 > Parasound pre > tone path output to GFA-555ii (to mains) and direct output to Rolls SX95> AX-596> LF12
Thoughts
So far? Positive!
The extra air/sound is foundational.
Right now, the LF12 are next to the 1C on the inner sides (I don't have room anywhere else up front, nor longer wire to try them at the 9 and 3 positions in my room, but when I have money for another 60ft of wire...).
I don't notice much interference from the cabinets, but I'm in the first round of tests. I'm mapping out potential diffraction/reflection mitigation with friends
Heretical Mod #7 is a success, so far
Originally, I wanted a pair of LF14 for the 5B I gave to my Dad.
https://polksda.com/pdfs/LF14Manual.pdf
(They're hard to chance upon, and I gave up actively looking for them.)
So, I decided to make my own.
Kinda sorta.
I mean, the Monitor 12 Series 2 has bigger LF genes in its bones- right?
https://polksda.com/monitor12.shtml
It's got the foundation for a great Frankenmod LF project.
And I do like to try new things...
The 5B are 3 States away but I have these 7B waiting to be reborn, plus my 1C are sitting there... wondering if some low-end reinforcement would sound nice.
Goal
Turn my M12 into a dual-use speaker; half Monitor, half LF approximation.
I want low-end reinforcement that matches the sound/speed/etc. of my vintage Monitors, not over-enhanced bass thump. I want even more vibration around upright bass strings, or more of that feeling of air on a big drumbeat. I don't want a room full of boomy tone.
Project outline
- Figure out how to make an M12 work as an LF12.
- Figure out the crossover issues.
- Make mods.
- Test
Easy, right?
What I did
- Mapped out a bypass 'circuit'. When it's connected, everything works per normal. Engage the bypass and the incoming signal goes straight to the mids.
- Figure out a crossover solution so I wouldn't burn anything out... Enter the Rolls SX95:
https://rolls.com/product/SX95
- Grab a back-up amp to test. My AX-596 is filling in, at least until I luck into something to replace my GFA-555ii on the 1C (or snag something else that's a good match for the role of the LF12). The 596 has a great damping factor, so it'll do for now.
- Mod the terminal plates and wire the bypass.
- Test!
Results
When the bypass wires are plugged into the upper terminals, it works like a normal M12.
When the bypass wires are disconnected, and the amp is plugged into the top terminals, the signal goes directly to the mids.
Signal path
WiiM Mini > Topping E50 > Parasound pre > tone path output to GFA-555ii (to mains) and direct output to Rolls SX95> AX-596> LF12
Thoughts
So far? Positive!
The extra air/sound is foundational.
Right now, the LF12 are next to the 1C on the inner sides (I don't have room anywhere else up front, nor longer wire to try them at the 9 and 3 positions in my room, but when I have money for another 60ft of wire...).
I don't notice much interference from the cabinets, but I'm in the first round of tests. I'm mapping out potential diffraction/reflection mitigation with friends
Heretical Mod #7 is a success, so far
The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * custom 5B on a system for my Dad * Ye Olde college stereo in the garage
Comments
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Due to an unexpected Radon issue in my catch-all workshop/office/stereo room, I'm behind on a lot of projects.
The LF12 tested well a month ago. I won't get to test them in a tidy, Radon-mitigated room for weeks, but the initial tests were wonderful.
58db peaks:
https://youtu.be/Zojac7rkb4s?si=GwVZ7WFzcFGrccBD
https://youtu.be/ujpbBeBY2co?si=IBqjw_0l1pBMh53d
68db peak:
https://youtu.be/fldmvL-B_RA?si=7voVPXXEOyg_uEPT
Not recorded:
Bring on the Night
That^ was splendid. I'll have it in the A/B testing with other listeners when I'm set up again. It's the first time I felt equal weight between Sting, Stewart, and Andy. It was great.
New goal = refurb the Yamaha p2250 for LF12 duty.
The AX-596 is adequate, but...
And later, it'll be nice to hear them with the 7B.The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * custom 5B on a system for my Dad * Ye Olde college stereo in the garage