The LX521 is a near perfect loudspeaker. It requires no modifications. But I have been afflicted with "Audiophile Tweaker disease", an insidious disease that affects both the temporal and frontal lobes of the brain, leaving the afflicted with a profound sense of confidence that they can "improve" the sound of any given system through self inspired manipulation and modification of the original design. What is documented below are my attempts at improving the sound of an already "fantastic" system - to eke out the last iota of performance.
LX521 MOD 1
MOD NUMBER ONE
Something about my ATI 6012 left me unsatisfied -- I think I was looking for a bit more smoothness in strings. While I enjoy solid-sate (and loath the amusical sweat syrupy sound many tube aficionados have in their systems) I wanted the natural edginess of brass instruments to only come out when it is required. The ATI was edgy, especially with strings. So, I had had good experiences with PASS LABS amplifiers in the past, and was confident that two X150 would be just the ticket to getting the kind of smoothness in the strings that I desired, while still retaining the explosiveness in the bass and brass that (to my ear) annihilate tube amps.
RESULTS FOR MOD ONE:
This was a good modification -- it was everything that I expected. I used a Bryston 2BSST^2 for the bass bins, and the X.150 for the upper midrange/tweeter arrays. This was a big improvement, albeit a costly one, but massed strings have the right woodiness and tone (no screeching ) as it did with the ATI. The overtones sound natural to me now.
MOD TWO -- SUPER ASP
MOD NUMBER TWO
A blueprinted ASP (Analogue Signal Processor).
Here I went a bit crazy -- I matched all the components and "blueprinted" the schematic.
Notice the LM4562 TO-99's** -- Every component is spec'ed/measured to be the schematic value -- I used a mix of Precision Resistive Products and IRC 0.1% Precision Metal Film resistors.... (lots of work -- all joints are MIL-SPEC/NASA inspect-able, using "Sn62/Pb36/Ag2" solder) -- all resistors/capacitors matched as closely as possible to the schematic.
The ASP is mounted up and singing, and I am currently building a mega FET regulated PSU to use with each individual ASP card, but in the meantime, I am using two of SL's suggested/normal ELPAC +/-12VDC PSU's -- one for each channel -- the channel transfer functions match very closely.
RESULTS FOR MOD TWO:
Wider and Deeper AS.
Greater Clarity and definition.
More impact and quicker transients.
** I went the TO-99 LM4562 due to the following quote:
I was part of a team that specified the LM4562/LME49720/10. I personally specified the LME49713CFB opamp as well as the LME49811 mono power amplifier driver parts which are my favorite parts sonically in the entire lineup. I also was the guy who pushed hard for the metal can packages which do sound better than the identical die in the plastic dip and SO packages. Bob Pease and I were going to try and find out just why that was but we never got the chance to do that and now I am gone and trying to enjoy some time off...while looking full time for a new job in the worst job market in decades!
Quoting myself on the LX521: "It also lends itself to modification -- I plan to out 'Magico' Magico with a 6061-T Aluminum/brass LX521 upper baffle -- it will be interesting to see if a further level of resolution can be gleaned from an already hyper-resolving system, if all the drivers are mounted in a rigid 18mm 6061-T Aluminum alloy baffle, one that (hopefully) allows every single quanta of motion to be converted into acoustic energy -- I repeat: that would be a very interesting modification to hear."
It took three months: my friend in Brazil works with machining oils (apparently, oils derived from coconut have some very interesting properties for machining) and he knew of a "Water jet" lathe company that could cut the baffle using the CNC drawings of the upper baffle. He also found a source for the 18mm 6061 stock. A month and 1/2 later, I had the baffles in hand. I sent them to Florida to be anodized. The company did a so so job (probably not enough current for such a thick piece of AL), and also took their own sweet time (another month), and instead of ORANGE, I got a light gold color. But that was fine.
RESULTS OF MOD THREE:
Huge improvement in sound.
Significant increase in perceived clarity and imagining.
This was what I was after. The mounting of the baffle against the wood base damped the entire baffle, and there was no ringing or metallic tang to the sound. A total success to my ears.
MOD FOUR Jensen Transformers ISO-MAX
MOD NUMBER FOUR
I had had some success in the past with bandpass filtering "cleaning-up" the audible range, and just for shits and giggles (and because I kept hearing a very low level whisper of hash or CB radio 'whispers') I inserted this before the ASP -- I was shocked at what an improvement it made to the overall sound. It really cleaned the system up, and added "stygian depths of silence" that are beautiful.
RESULTS OF MOD FOUR:
Removal of low level hash.
Very low noise floor -- made the overall system much quieter
MOD NUMBER FIVE "Borosilicate"
MOD NUMBER FIVE
I met a fellow Audiophile that has a pair of Mioljub R. Nestorovic designed loudspeakers. I started to investigate his designs, and came across what I thought was a novel solution to damping -- using "thermal paint" for sound damping. Mr. Nestorovic had discovered that a sodium borosilicate microsphere paint additive was quite effective in damping wood, and he used this process on his loudspeaker cabinets. I decided to try this on my AL baffles, not so much because I heard any ringing, as to "ward off" comments on ringing by "mouthy" guests -- I kept getting comments such as "boy, that must ring badly" etc. etc. I mixed it with some high quality black enamel, and painted it thin enough to have no effect on the baffle thickness.
RESULTS OF MOD FIVE:
Peace of mind.
Stick to beat off non-believers.
MOD SIX: New XP-20
MOD NUMBER SIX:
Through my friends at RENO HI-FI, I was able to get a good deal on an XP-20, trading in my XP-10. Boy -- am I ever glad that I did -- I am a strong believer that the PRE-AMP makes a significant contribution to the overall sound -- and it most certainly does, in this case.
RESULTS OF MOD SIX:
MOD SEVEN: In Progress
MOD NUMBER SEVEN:
(The "last" (??) MOD)
I am buidling JFET regulated PSU's for each channel of the ASP. Checking to see what DC voltage the op-amps are most linear at -- seems like a Rail voltage of +/-17vDC. Getting close, stand by ...
MOD 8 -- New bass amp
MOD NUMBER EIGHT:
Number Seven was not the last modification to the system. I swapped the Bryston for an Emotiva SA-250 amplifier. Very powerful, and the damping factor is much higher, so there is greater control of the bass.