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LXmini
LXmini+2
LXstudio

LXmini+2 & LXstudio Supplies
LX521.4

 

LXmini+2 & LXstudio Supplies

 

miniDSP 4x10HD in a box

A Digital Signal Processor is used to generate the appropriate woofer/midrange and tweeter drive signals for the power amplifiers, which are connected to the LXmini and the woofer drive signals for the dipole woofers of the LXstudio. 
A Configuration File is provided with the LXstudio Construction Plans, which needs to be loaded via USB from a computer into the DSP unit. 

The miniDSP 4x10HD is ready made with both analog and digital inputs and has volume control. The unit can be trained to recognize Oppo/Sony/Philips IR remote controls. It thus also replaces the preamplifier. But the DSP lacks an indication of volume level. You need to purchase:
1 x  miniDSP 4x10HD
1 x  4x10 plug-in firmware to structure the DSP for XO/EQ applications
  

Rear of miniDSP 4x10HD

    

 

miniDSP 2x4 in a box

The miniDSP 2x4 has analog inputs only and lacks volume control. A single miniDSP 2x4 can be used for the LXmini and configured with the 2way Advanced plug-in. 
Two units, one for left channel and one for right channel, are used for the LXmini+2. In that case you need the 4way Advanced plug-in to configure each unit. Configuration files are part of the LXsub documentation.
 

 

 

ATI Power Amplifiers

For many years I have been using ATI power amplifiers. In their product line the 12-channel AT6012 power amplifier is well suited to the LXstudio.  Each driver would have its own 60 W stereo amplifier, which can provide as much peak current or peak voltage as I would ever want in my 100 m3 listening room at The Sea Ranch. 

The AT6012 is rated at 60 W per channel into 8 ohm FTC full bandwidth output power, with all 12 channels driven simultaneously. The power supply has high current reserve and a 2000 VA transformer. A pair of LXstudio speakers utilizes 8 amplifiers, which leaves 4 amplifiers for any future use, for example the LX521.4, which would take 10 amplifiers. A separate amplifier channel is allocated to each of the 10" dipole woofer drivers to obtain output capability that is commensurate with the midrange, yet minimizes bottoming and the risk of mechanical damage to the woofers, or having to reduce the speaker's low frequency extension. At very high sound levels the amplifiers clip first, which gives a clearly audible warning to turn down the volume. 

The AT6012 exhibits good low power intermodulation distortion performance as seen in the graphs above. It is primarily 3rd order at 1 W in response to equal amplitude input signals at 1 kHz and 5.5 kHz driving an 8 ohm resistor. Harmonic distortion products are always of lower amplitude than intermodulation products. Unlike for many Class A/B amplifiers the distortion does not increase as power goes down. A 100 mW output level is not unrealistic. Early transistor radios had 50 mW output stages and made quite a bit of noise.

The AT1806 is a six-channel power amplifier rated at 180 W per channel. It can drive the LXstudio, if the two 10" drivers in each woofer baffle are connected in parallel to one amplifier. The parallel drivers present a low 2 ohm impedance to the power amplifier around 100 Hz. The power amplifier driving this load must be capable of at least 200 W into 4 ohm.  The AT1806 is capable of producing higher bass output volume from the LXstudio than the AT6012 and handle extreme loudness peaks. The DSP crossover/equalizer requires no modification for its use. 
But, the higher power has the potential to bottom out and damage the woofers below 40 Hz and to overheat or stress LXmini woofer/midrange and tweeter with high level test or transient signals. I never had a failure with program material even at extreme volume levels.

The intermodulation distortion performance of the AT1806 at low power levels is exemplary.

The AT1202 is a two-channel power amplifier rated at 120 W per channel. It would be needed to drive left and right LXmini tweeters, if the  AT1806 powers each dipole woofer driver individually and also the LXmini woofer/midrange drivers. The AT1202 is a little safer for the LXmini tweeter than the AT1806. In any case caution is advised with such high power amplifier setup. 

The intermodulation distortion performance of the AT1202 at low power levels is very good.

Note that my power description is for peak voltage equivalent power. A 2 Vpeak sinewave at 1 kHz and a 2 Vpeak sinewave at 5.5 kHz superimpose and fluctuate at a 4.5 kHz rate as seen on an oscilloscope. The fluctuation has 4 Vpeak amplitude, which I call equivalent to "1 W" for the conventional single frequency sinusoid of 4 Vpeak or 2.83 Vrms across 8 ohm. Similarly the "100 mW" description is for 1.26 Vpeak of the superimposed sinusoids. The actual dissipated powers are 500 mW and 50 mW into 8 ohm. 
Harmonic distortion products are below 0.01% for the three amplifiers measured. But musical signals are rarely single sinusoids. Intermodulation distortions are always higher than harmonic distortions and their spectral distribution is in my opinion a better differentiator between amplifiers than a single harmonic distortion number.

ATI making an amplifier -- ATI sales story

 

 

Other Power Amplifiers

A wide range of power amplifiers can be used for the LXstudio. The primary requirement is that they all have the same voltage gain, otherwise you need to adjust the gain defined by the LXstudio configuration file for the miniDSP 4x10HD. I have heard good things from a trusted source about the Outlaw 7075 7-channel amplifier, which measures similar to the AT6012.  Here are examples for which I have some measurements.

amp-parasound-a51.jpg (72933 bytes) amp-Pass-proto.jpg (78739 bytes) amp-pluto-90mW.jpg (79342 bytes) amp-pluto-470mW.jpg (73141 bytes) amp-UPA500-100mW.jpg (79478 bytes) amp-UPA500-470mW.jpg (75159 bytes) amp-miniX-100mW.jpg (74360 bytes) amp-miniX-480mW.jpg (76218 bytes)
Parasound A51 Pass Labs proto Pluto LM3886 Pluto LM3886 Emotiva UPA-500 Emotiva UPA-500 Emotiva Mini-X Emotiva Mini-X
amp-Outlaw-7075-1W.jpg (61732 bytes)
Outlaw 7075
amp-Hypex-UcD180.jpg (76780 bytes)
Hypex UcD180

Internals of Outlaw 7075 and Dave Reite's UcD180 based 8-channel DIY power amplifier:

 

 

Drivers, Wood Flat-packs & configured DSP

Madisound, the distributor of SEAS drivers in the US, offers a complete LXstudio/LXmini Driver Kits of woofer, midrange and tweeter drivers.  
Madisound offers a NC-machined flat-pack of wooden parts for DIY assembly of the baffles. 
Contact Adam Johnson.

www.magicLX.com in Germany offers a complete CNC machined wood flat-pack and parts kit, including all drivers, for building the LXmini+2 or LXstudio. Different wood finishes are available. They also offer >50% assembled cabinets with drivers mounted and an assembled and tested DSP+amplifier PowerBox as well as ASP+amplifiers. Turn-key systems available They ship world-wide.
Contact Frank Brenner after having studied the www.magicLX.com website for your needs.

           

PowerBox 6pro Ncore (DSP-based), configurable for all LX speakers

PowerBox 6pro Ncore precision analog (ASP-based), configurable for LXmini/+2/studio 

PowerBox 4180 & PowerBox 6pro Ncore & PowerBox 6pro NCore precision analog configurations for LXmini, LXstudio and LX521 Turnkey Systems or Kits and a Price List.

In the UK contact Jerry Bloomfield at Falcon Acoustics Ltd for an LXstudio Kit.

Buyers of cabinet kits or PowerBox must own LXstudio & LXmini Construction Plans ($160). 
See below for ordering, shipment cost and payment.

 

The LXstudio Construction Plans are available as PDF only and consist of two parts: 

    LXmini Construction Plans  +   LXsub Construction Plans.

To order the LXstudio plans choose these two items from plans, CDs downloads (or navigate to magicLX.com or Madisound)

 

 

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Visit to hear the LXmini, LXstudio or LX521.4

                             

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What you hear is not the air pressure variation in itself 
but what has drawn your attention
in the streams of superimposed air pressure variations 
at your eardrums

An acoustic event has dimensions of Time, Tone, Loudness and Space
Have they been recorded and rendered sensibly?

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Last revised: 11/29/2018   -  1999-20187 LINKWITZ LAB, All Rights Reserved