Monthly Archives: March 2018

An ARTful change to the ART7

I noticed the last few times that the Dynavector XX2 Mk. II was souding a bit strange.  Oddly, I’d say it sounded “cheap” as it has not been tracking very well, reminding me of the muddy sound of some of the cheap phono cartridges I used to own (like the crap Ortofon I had on a Dual turntable).  It not only has been sounding very congested, there was dull sibilance where I don’t remember it being before.  Something’s up, and I need to send it out to be looked at.

I needed a replacement. I had a few on my short list (like the excellent, musical Hana SL), but ultimately ended up with the Audio Technica ART7.  For the uninitiated, this is a low output moving coil with “special line contact” stylus on a boron cantilever.  I got it lined up using the MintLP protractor, and still have yet to finish dialing in the SRA and azimuth.

Right out of the gate, it is an excellent tracker, the best I’ve had since retiring the old V15 Type V.  It still has a few dozen hours to fully break in, but it has a lot of clarity going for it with the improved tracking ability.

The only achilles heel right now is the phono stage–I am really not liking how noisy the Phonomena II+ is.  I’ve even replaced the $1.50 chinese switching mode power supply with a linear regulated power supply, but the noise remains. This is basically “amplifier rush,” that white noise that comes from high-gain amplification.  I have records so quiet that the noise from this phono stage is audible over the vinyl’s background noise.

I am only afraid that if I replace it, the replacement will also have similar noise. Step-up transformer? Perhaps, but I got this phono stage to eliminate having yet another device in the system, and to have many loading options available.

On my short list is the Pro-Ject Tube Box DS2, largely due to its two selectable outputs, one of which I can sum to mono using a Y adapter at the output and use in a spare input on the preamp.  I can also roll tubes to shape the sound as needed.

No longer an Amazon Prime subscriber

OK, I admit it–I was an Amazon Prime subscriber for a few years.  I took advantage of an attractive student discount where I paid half the normal Prime rate.  When my last renewal came up, it would have been for the full $99/year subscription rate.  Looking at it for more than a few minutes, I realized what a poor offer it really is for me.

Amazon Prime offers both free two-day shipping and now, access to certain video programming.  It offers other benefits I’m sure, but I really only wanted to have access to the fast, free shipping.

The problem is, I never watch video on Amazon, nor do I use any other Prime services, so I am paying for something I never use.  Two day shipping?  Only in rare cases have I ever needed something in two days.  The way Amazon has been opening up distribution centers lately, most of my orders from their warehouses have been arriving in two days anyway.  As for the free shipping, it takes me almost nothing at all to come up with a $25 order to meet their minimum.

If I am in a situation where time is of the essence, I could pony up for a single month’s Prime subscription.  So it is not like it is totally inaccessible.  But otherwise, Amazon has improved enough in other areas that I really don’t need to pay for a full-blown yearly membership.

What I would really like to see is a service called Prime Shipping.  Offer it for $39 or $49/year and I may just resubscribe. And it might bring others on board who feel the $99 price is too steep and, like me, have no use for the other Prime benefits.

 

TubeCube|7 — A nice little desktop power amp

I picked up the TubeCube|7 a few years ago.  I’d never owned a true tube power amp before.  I knew that this amp would never find a place in my main system, as it only puts out a tiny 3.5 watts per channel.  Yet I had a perfect use case–I was retiring my Altec Lansing computer speakers (which sounded OK, but had an annoying background hiss whenever the system was on), and wanted to up my game a bit.

Late night listening by the glow of vacuum tubes…

Since getting the Oppo BDP-105, I had a spare DAC–a Cambridge Audio DACMagic.  With a newly-built computer, I used the optical Toslink connector from the computer to the DAC, in order to isolate it completely from the computer.  (No, I’m not one of those who feels Toslink is worse than Coaxial–there is a reason our Internet backbone runs on fiber vs. copper!)

I also needed speakers for the new computer desk–I located a used pair of Boston Acoustics CR65 bookshelf speakers that fit the side shelves perfectly.  I knew bass would be no great shakes with these speakers, so I picked up a Dayton 6.5″ powered subwoofer which tucks neatly under the desk.  The CR65s have one flaw in that there is a resonance hump at 125Hz.  I had to notch that out in JRiver.  Much as I hate using digital EQ, this helped clean up the speaker’s response, at least until I can get in there and brace the cabinet, and perhaps deaden the cabinet walls and/or add some fiberfill to help out with that resonance.  Beyond that, the speakers have a nice midrange and the highs are easygoing.

Before permanently installing the TubeCube|7 in my desktop system, I gave it a try on the big rig.  My speakers at the time were not terribly inefficient (they were around 89-90dB/w efficient), but this amp struggled to get a usable volume out of them.  This amp may work well with horn-loaded speakers with high efficiency, but don’t expect it to drive most typical speakers today without running out of gas quite quickly.  The bass in this case was rather ill-defined, since there simply was not enough current to drive the woofers.  What also didn’t help was that there was a rolloff in the highs–everything sounded dulled through the amp.  After purchasing it, I found another review online which echoed my comments, and backed it up with measurements for exactly what we were hearing.

I don’t know, then, if it was the amp’s circuitry that was rolling off the highs, or the unidentified Chinese tubes that shipped with it.

I did replace the tubes about 18 months after buying the amp–I went with new production Mullards–a pair of EL84s, and a 12AX7.  I noticed the sound is slightly cleaner and less gritty.  Did the highs improve?  No.  These tubes might have helped with added smoothness but provided no change in the rolloff.

One tweak I have yet to make is to use a crossover for the amp. The speakers are currently running full range.  Blocking the frequencies below 100Hz would go a long way towards improving headroom a bit, since the amp would not be struggling with the bass.  Parts Express sells a pair of crossover RCA plug adapters in various frequencies, so those may work out perfectly for this installation.

EDIT: See my updates about the amp.