Nelson thanks for the confirmation.
So I measured the 100 or so J113s that I have and found that they are all more or less from the same batch with Vp between 1.5 and 1.99V. The Idss is 19 to 22mA. So I breadboarded the LXminStudio Sub filter and finally got an acceptable response curve measurement. I then checked both the THD and the swing limitations (with my limited means) and am satisfied with the results.
Here some data points:
For a single J113 buffer I can get the THD down @ 1KHz to .006x% (take this as a relative indication with my measurement set up: Focusrite Scarlet2i2, REW or ARTA). Interestingly the CCS source resistor at 140 to 150 ohms sets the stage but the load resistor at around 9kOhms (vs. 10kOhms) makes a difference in THD.
For the complete Sub filter the THD @ Freq. less then 40 Hz the whole set up is feisty ( a lot of 50Hz noise etc.) but shows THD .x%.
Base Boost is there: @12Hz just under +6dB
Output Swing: About 20 Vpp at the output at 12 Hz at clipping onset (gestimated from scope). For what I need this should be house shaking.
Anybody see anything off the mark on this way forward?
So I measured the 100 or so J113s that I have and found that they are all more or less from the same batch with Vp between 1.5 and 1.99V. The Idss is 19 to 22mA. So I breadboarded the LXminStudio Sub filter and finally got an acceptable response curve measurement. I then checked both the THD and the swing limitations (with my limited means) and am satisfied with the results.
Here some data points:
For a single J113 buffer I can get the THD down @ 1KHz to .006x% (take this as a relative indication with my measurement set up: Focusrite Scarlet2i2, REW or ARTA). Interestingly the CCS source resistor at 140 to 150 ohms sets the stage but the load resistor at around 9kOhms (vs. 10kOhms) makes a difference in THD.
For the complete Sub filter the THD @ Freq. less then 40 Hz the whole set up is feisty ( a lot of 50Hz noise etc.) but shows THD .x%.
Base Boost is there: @12Hz just under +6dB
Output Swing: About 20 Vpp at the output at 12 Hz at clipping onset (gestimated from scope). For what I need this should be house shaking.
Anybody see anything off the mark on this way forward?
Hello,
I just completed ACN for my LXMini and test running right now and wondering what the output potentiometers (x4) should be set to...
According to the guide, start with all the way up. Do we normally leave it to all the way up?
Comparing with 2x4 HD digital crossover, it sounds clearer and has better resolution. However, it became lacking warmth and is a bit thin sounding. This is a similar effect to when I tried passive preamp instead of active preamp for another speaker set up.
I just started running so it may just need run in to become smoother....
If anyone enlighten me what those 4 pots does if I turn them down, it would be greatly appreciated. Thank you....
I just completed ACN for my LXMini and test running right now and wondering what the output potentiometers (x4) should be set to...
According to the guide, start with all the way up. Do we normally leave it to all the way up?
Comparing with 2x4 HD digital crossover, it sounds clearer and has better resolution. However, it became lacking warmth and is a bit thin sounding. This is a similar effect to when I tried passive preamp instead of active preamp for another speaker set up.
I just started running so it may just need run in to become smoother....
If anyone enlighten me what those 4 pots does if I turn them down, it would be greatly appreciated. Thank you....
Hello great comunity ,I am a beginner and try to understand how to use the LX-mini crossover for and old 2 way speaker presented many years ago on "costruirehifi" magazine equipped with mid-woofer RES 13FC8 (was SIARE 13V8) and tw AUDAX TW034X0.
The passive crossover is a compromise between a Butterworth and Linkwitz network, mediating between the electroacoustic peculiarities of the two configurations with an fc about 2000Hz, the attenuation of the tweeter is regulated by the resistances R1 and R2 of the attached schematic.
I followed the cubicincher user approach by creating the same bandpass between 50Hz and 2500Hz (C1=100nF on simulation) for the mid-bass and a LP filter
set to fc 2000Hz .z
For my point (better noob ) of view the microcap simulation would seem correct, I'd like to have your opinion.
The passive crossover is a compromise between a Butterworth and Linkwitz network, mediating between the electroacoustic peculiarities of the two configurations with an fc about 2000Hz, the attenuation of the tweeter is regulated by the resistances R1 and R2 of the attached schematic.
I followed the cubicincher user approach by creating the same bandpass between 50Hz and 2500Hz (C1=100nF on simulation) for the mid-bass and a LP filter
set to fc 2000Hz .z
For my point (better noob ) of view the microcap simulation would seem correct, I'd like to have your opinion.
Attachments
Yes, I run my crossover with the pots all the way up.Hello,
I just completed ACN for my LXMini and test running right now and wondering what the output potentiometers (x4) should be set to...
According to the guide, start with all the way up. Do we normally leave it to all the way up?
Comparing with 2x4 HD digital crossover, it sounds clearer and has better resolution. However, it became lacking warmth and is a bit thin sounding. This is a similar effect to when I tried passive preamp instead of active preamp for another speaker set up.
I just started running so it may just need run in to become smoother....
If anyone enlighten me what those 4 pots does if I turn them down, it would be greatly appreciated. Thank you....
I believe the pots are there to help balance the sound. For example, if the low end is too heavy, you could turn the low pots down and find a balance point between the highs/mids pots at full and the low pots decreased.
Hello decommo (post #922),
exactly what wg45 wrote above. It depends on what efficiency (dB/W/m) your drivers/speakers have
and what kind of amplifiers you use.
You have to adjust the volume between the low pass and the high pass.
Most often you need a slightly more powerful amp for the bass/midrange than for the mid/highs.
But you can adjust the difference over the volume pots.
Happy testing and listening! 🎼🎷🎸
Cheers
Dirk
exactly what wg45 wrote above. It depends on what efficiency (dB/W/m) your drivers/speakers have
and what kind of amplifiers you use.
You have to adjust the volume between the low pass and the high pass.
Most often you need a slightly more powerful amp for the bass/midrange than for the mid/highs.
But you can adjust the difference over the volume pots.
Happy testing and listening! 🎼🎷🎸
Cheers
Dirk
Maybe try a warm preamp in front? Could be that the 2x4HD was doing some bit destruction, but had a better preamp for stronger output. That is my highly unqualified guess.Hello,
I just completed ACN for my LXMini and test running right now and wondering what the output potentiometers (x4) should be set to...
According to the guide, start with all the way up. Do we normally leave it to all the way up?
Comparing with 2x4 HD digital crossover, it sounds clearer and has better resolution. However, it became lacking warmth and is a bit thin sounding. This is a similar effect to when I tried passive preamp instead of active preamp for another speaker set up.
I just started running so it may just need run in to become smoother....
If anyone enlighten me what those 4 pots does if I turn them down, it would be greatly appreciated. Thank you....
Nice to hear that it had more resolution. This is exactly my theory, and why I sold my 4x10HD in favor for the 6-24 analog crossover. I plan to use several B1 Triodes, keeping it «NP» all the way. I received my digikey order tonight!
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The pots allow for adjustment in case the gains of the two amps driving the two (bass vs midrange and up) drivers differ.
If you use amps with the same gain (for example, identical amps) then you can just leave the pots wide open.
Of course, you are free to adjust them (within reason) for your personal preference.
If you use amps with the same gain (for example, identical amps) then you can just leave the pots wide open.
Of course, you are free to adjust them (within reason) for your personal preference.
https://www.firstwatt.com/sims/LX_MINI_V1R0.CIR
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anyone can post it here? I'd like to lower bass frequency around below 300HzMay I ask what is the common power supply for 24V DC for this ACN? I am powering it with laptop power adapter which is 24v 2A. It looks quite a good quality but getting this high pitch background noise. I cannot hear this noise when music is on but it small but noticeable noise is noticeable whenever there is a pause or no music playing. My suspicion is that the power adapter is the cause of this noise.
I recorded the noise and uploaded on youtube. Can anyone tell me if this might be from power adapter?
If so, may I ask which power adapter that you use that offers clean no background noise?
Thank you..
I recorded the noise and uploaded on youtube. Can anyone tell me if this might be from power adapter?
If so, may I ask which power adapter that you use that offers clean no background noise?
Thank you..
Finally up and running and here it is. It has been quite a while since I last heard them in the all Class D configuration so sound quality memory my be weak but after some break-in it sounds good. The subs are still Class D powered and the bass is great. My 35 Hz room mode is alive and well but only sometimes over powering. Need to look into this when I get around to finally setting up the LX-minis properly.
A special thanks to Nelson for his design, support and patience (with me ) on this endeavor. Well worth having the LX-mini's singing again.
A special thanks to Nelson for his design, support and patience (with me ) on this endeavor. Well worth having the LX-mini's singing again.
Attachments
Dear all,
I'm ordering materials for the firstwatt asp at the moment.
I have a question about the firstwatt asp lxmini crossover.
my current configuration: 2x4HD minidsp -> preamp volume control -> power amp.
the new configuration: Meridian DAC -> firstwatt asp -> preamp volume control -> power amp.
When I read the documentation from Nelson I understand that the lowest distortion is reached by very low input/output voltage.
this means that the new configuration should be:
Meridian DAC -> preamp volume control -> firstwatt asp -> power amp.
My question is how do you use the asp crossover ?
would like to hear your reaction
Kind regards,
Gerard
I'm ordering materials for the firstwatt asp at the moment.
I have a question about the firstwatt asp lxmini crossover.
my current configuration: 2x4HD minidsp -> preamp volume control -> power amp.
the new configuration: Meridian DAC -> firstwatt asp -> preamp volume control -> power amp.
When I read the documentation from Nelson I understand that the lowest distortion is reached by very low input/output voltage.
this means that the new configuration should be:
Meridian DAC -> preamp volume control -> firstwatt asp -> power amp.
My question is how do you use the asp crossover ?
would like to hear your reaction
Kind regards,
Gerard