Sony 730ES

I am continuing to use the Sony ST-S730 ES tuner in the kitchen, and as I've been busy sorting my stuff from my former workplace and integrating it into my new home headquarters, it's about all I've been playing for the past three weeks, to the local classical and jazz stations through my on-roof whip antenna.

The 730ES is unimpressive in grabbing distant stations, but on local stations it sounds great, perhaps one of the best sounding FM tuners ever.  James Bongiorno famously checked it a prototype for Sony and said it had the lowest distortion he'd ever measured--until it drifted.  He told Sony the drift was unacceptable, and he didn't believe later they'd fixed it.

I have not noticed any drift in my 730ES.  The similarly good (better at distant stations, but equally good sounding) Kenwood L-1000T has horrible drift, and since Bongiorno was a longtime admirer and critic of Kenwood tuners, I sometimes wonder if Bongiorno had gotten the two confused.  (He'd be outraged at such a thought, no doubt.  He never confused anything.)  Of course, it's easy to "see" the drift on the L-1000T because of the built-in (but low resolution) LED spectrum scope the tuner has as a tuning indicator.  The Sony has no such fancy indicator, only a dumb strength meter that simply maxes out on nearly any signal.  Perhaps if I was measuring the distortion I'd notice the drift.  But also I can hear the drift on the Kenwood--It drifts about 50kHz off in 24 hours of operation.  Which I can compensate with the fine tuning controls.  So I use the nominal positions if the tuner has just been turned on, and another setting (-50kHz) if I keep the tuner running 24/7, which currently I'm no longer doing as the better antenna the 730ES is connected to now is so much better it makes it pointless to run the L-1000T on the old indoor antenna it is connected to.  I may swap in the L-1000T on theoutdoor antenna soon, but while perhaps slightly better sounding it's much less easy to use from the front panel.

Here's a great inside picture of the Sony ST-S730ES.  It's not as impressive inside as the Kenwood, but it's more impressive looking inside than other top Sony digital tuners, and top digital Yamahas like the TX-1000.  I sometimes had regrets not getting a possibly more well known Sony ST-5, but from the inside the 730ES seems to have all that tuner did, and more.

One downside, and perhaps it's just my kitchen system, but sometimes there is simply way too much bass at some low frequency I've never figured out, perhaps 20-30 Hz.  I'm thinking it might arise from some kind of PLL error.

Trying to use cheap ASUS notebook for REW

With existing equipment, I have been unable to use the signal generator output of my cheap i3 ASUS notebook with Windows 10 because:

1) The headphone jack has to be plugged in just at the right time (after the Realtek audio driver is running apparently) in order for a popup menu to appear to allow you to select the jack use as a "speaker" output.  Otherwise, REW generator plays on the very limited built-in speakers.

Perhaps it's nice to have this flexibility, but IMO plugging in the headphone jack should immediately and without question stop the internal speaker, at least by default.

2) The output of the jack is hugely noise with hum and spikes, so much I can barely see a 1kHz signal at the default -12dB, or even -3dB, amidst all the noise, on my scope.

3) Somehow despite all the noise, the THD+N measures a "mere" 4.5%  I had to tune my ST1700A to 999Hz for the PC audio signal to lock.

4) My Emu 0404 is long not supported.  It was a true pain in the neck to get the drivers installed, I only found out by internet search that you need to turn ON the unit WHILE it is already plugged into USB and the PC is running.  THEN and only then will it identify itself to the installer program as the genuine EMU product, so installation will proceed.  But apparently the only drivers I have found so far, the V1.40 drivers, do not actually work on Windows 10.  People have had better success with the V1.35 drivers, but I have been unable to find those so far.

What happens with the V1.40 drivers is that when the EMU is turned on,  everything related to sound locks up.  So REW won't work, the even the Realtek preferences is frozen.  To free this freeze, a reboot of the system is required.

Both the V1.40 and V1.35 drivers were beta drivers for Windows 7.  There is no non-beta driver subsequent to XP and there is no "Windows 10" driver of any kind.

I have on order a modern USB DAC that is highly praised at the Audio Sciences Forum.  That MIGHT make this PC useful.

For speaker input, I was able to get the miniDSP usb microphone to work ok.  It's just output that's an issue.

Audiosource Amp One/A

I bought one of these a few years back for the second bedroom amplifier.  I could not get it to be quiet enough (< 15dB) from mechanical hum for this very quiet room (with noisy AC power) and also it seemed there was unavoidable hum from the speakers.  So I moved it to my office, where I hardly ever used it.  I got a better engineered Parasound Zamp for the second bedroom, and then I figured out the hum problem had been caused by the use of STP ethernet cable to connect the Sonos zoneplayer and NOT the Audiosource amplifier.

I think I paid $200 or less for the Audiosource.  It feels quite heavy, almost as heavy as a Parasound HCA-1000A--a much more expensive and powerful amplifier, with much of the weight coming from a toroidal power transformer.

However, despite the apparent weight, specs do not suggest all that much power: 50W/ch into 8 ohms and 60W/ch into 4 ohms, both channels driven, at 0.2% THD.

With one channel driven, I got over 110W/channel into 8 ohms from 1kHz to 50kHz.  I was surprised by the full power bandwidth to at least 50kHz.  The power dropped slightly to 105W at 20Hz.  A loss of power at low frequencies suggests softness in the power supply.  But at twice the rated power (in one channel only).

Distortion measurements were way better than spec, with THD at 0.018% at 1kHz, 0.02% at 20Hz, and 0.07% at 20kHz.  Hum and noise were about as low as I have seen in one channel, but not quite as good in the other.  This amplifier meets audio objectivist high fidelity standards.

Unlike most more recent power amplifiers, it has a hardwired ungrounded AC connection.  If the transformer were to develop a primary short, that could be a lethal problem.  I see no UL, CSA, ETA, or CoLA approvals.  However, note that virtually all hifi electronics up to 1980 were like that, and even since 1980 most "midfi" stereo or home theater receivers are also ungrounded.  However, some major brand receivers DO have some kind of regulatory approval anyway, which I think requires something like double insulation (for example, the transformer is electrically isolated from the chassis).  Lacking a ground connection often means that ground loop issues would not be as difficult as with fully grounded amplifiers, however this is not always true (and my own experience with this amplifier confirms that).

I now plan to use the quieter channel for small speaker testing purposes.