Thursday, December 14, 2017

FrankenTurntable and Speaker Upgrades

I've been helping a friend of mine with his stereo recently and it got me energized to do some work on my own. First of all, I decided to finish a long-term project of mine that's been on hold since my daughter was born: assembling a turntable out of myriad spare parts, most of which I already had lying around.
The platter and mechanism came from a frustratingly crappy direct-drive linear-tracking turntable that I rescued from the trash. I bypassed all of the control circuitry and wired the power directly to the motor, so it only turns at 33 1/3 RPMs (i.e., no 45s for me), but it seems to be pretty solid and consistent at that, at least. I'm interested in trying some different platter materials at some point, but I doubt the motor has enough torque to handle anything much heavier than the one it came with.

The tonearm comes from a Technics SL-1950. I bought this one used off of eBay for about $50. I mounted it to some spare blocks of wood I had lying around and purchased some long, skinny nuts and bolts that I used to raise it to the appropriate height for the platter and get it leveled properly. I also used the wood to sandwich some female RCA jacks that I spliced onto the tonearm's own wires so that I could hook it up to my preamp using standard RCA cables (the yellow jack is the ground line).

It sounds really good and, despite looking ghetto af, it has a nice, post-apocalyptic DIY charm that that appeals to me. More importantly, though, this raw setup provides a direct line from the tonearm to the preamp/amplifier without any of the circuitry in the way that can lead to signal degradation in many more user-friendly turntables (like my LP-120 before I modded it for a direct connection, as well).

If you'd like to hear the output, it's the turntable I used to make the recordings for my cartridge comparison post.

Next up, I've been giving my Dared VP-20 tube amp a rest lately and am instead using a Lepai LP-2020TI tripath amplifier I purchased from Parts Express. It seems Lepai is no longer producing the original model, the LP-2020A+, which is a shame since it was so well-loved among audio enthusiasts, but they are making what is essentially a clone using a more easily sourced chipset (it pumps out a few extra watts, too, which is nice). It has the same clean, low-distortion sound as the original (as long as you keep the volume dial below about 11 o'clock, just like the original...) and, as much as I like my tube amp, the Lepai provides a clear accuracy that can be a refreshing change of pace from the folksy warmth of the tubes.

Finally, I overhauled my backloaded horns--which I originally fitted with some cheap but adequate drivers from MCM Electronics--with some really nice Tang-Band full-range drivers. Since the MCM drivers are only good to about 4 kHz, I had them set up on a 3-way crossover with some Bohlender Graebener Neo8 midranges. It sounded good, but I've always heard that full-range drivers running uncrossed sound more "realistic" than 2-/3-way setups.

So, I hooked the Tang-Bands up uncrossed with the ribbon tweeters wired in parallel (the Lepai can push the combined 4-ohm load just fine), and sure enough: they sound a lot brighter and more even than the crossed 3-way setup, likely due to the Tang-Band's hump above 15 kHz combined with the natural lack of sensitivity mismatching.

The Tang-Bands are supposed to be good down to 60 Hz, but they were barely usable down to probably 80-100 Hz or so (I suspect the chambers in my horn boxes just aren't large enough for the rated performance), so I definitely need my 15" subwoofer in the mix now (my old 3-way setup benefited from it, as well, but it wasn't strictly necessary). Likewise, the ribbon tweeters are supposed to be on high-pass filters for safety, but I'm pushing such a light load through them that I'm pretty sure they'll be okay.

Phono Cartridge Comparison: At95e vs Ortofon Omega

I recently assembled a franken-turntable from bits and pieces I salvaged from other systems, but one of the pieces I needed to complete it is a new cartridge. I already had an At95e from Audio Technica, which is well known and well regarded among turntable aficionados as a solid budget cartridge, so I thought I would mix it up a bit and purchase another favorite from the budget realm, the Ortofon Omega. Both of these cartridges are available for around $35-40, so I figured it would be a good, fair fight. Reviews online tend to refer to the Omega as "warmer" than the At95e, which is known as a "sterile" but "accurate" performer.

Audio Technica's At95e
For testing, I took two short recordings with each cartridge from the 'tape monitor' output of my preamp, which sends a full-output signal (i.e., bypassing all of the volume and EQ from the preamp aside from applying the Redbook boost to the phono stage) directly into the audio input of my Lenovo Thinkpad laptop. I used Steely Dan's Showbiz Kids (track 1 from side B of the first disc of Steely Dan's Greatest Hits double LP) and Dr. Dre's Nothin But a G Thang (coincidentally also track 1 from side B of the first disc of The Chronic 180g vinyl remaster). I didn't do any EQ/processing/declicking, just removed the dead space at the beginning and normalized both tracks to -1 dB because the At95e put out a slightly louder signal and we typically think louder things sound subjectively better.

The Ortofon Omega
You can download my test recordings here. (Note: these recordings are short and only include the intros of the songs, and I believe them to be covered by Fair Use). I did my testing using the Lacinato ABX audio testing software, which is free to use, listening via Audio Technica ATH-M50 closed-back headphones.

If you wish to remain impartial, please do your listening/testing before reading any further.

Ok, so first off, the results are extremely close. I think anyone would be very happy with either of these cartridges for the prices they typically go for. In simple, unblinded A/B testing, I feel like I was able to hear a consistent difference between them, mostly in the vocal midrange. The At95e sounds a little roomier while the Omega sounds very tight. Whether one would consider either to be better than the other probably depends on the words I use to describe them (e.g., roomy vs loose/sloppy, tight vs constricted). I honestly don't think I prefer one over the other, it's just a slightly different character.

In proper blinded ABX testing, that all fell apart and I wasn't able to reliably tell them apart. I did about a half-dozen comparisons and my best accuracy rate was around 67%, but more often I hovered around 50% and my confidence was always quite low.

So, there you have it. Both are good budget cartridges with no major differences as far as I could tell. I noticed no difference between them in "warmth" or "accuracy," whatever that means. You should probably take reviews claiming otherwise (e.g., suggesting one or the other is better for this or that kind of music, etc.) with a grain of salt. Feel free to leave a comment with your own ABX results.

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