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Cary CAD-1610-SE monoblock power amplifier Measurements

Sidebar 3: Measurements

The first thing I do when I hook up an amplifier in the test lab is to set the Audio Precision System One to measure distortion. Then, to get the lowest possible reading, I experiment with all the different ways of grounding the device being tested to the test gear. That way, I know that the noise and distortion levels I measure are truly indicative of the amplifier's performance and are not due to some freak of grounding in the lab.

However, when I manhandled the first sample of the monster Cary CAD-1610-SE down the stairs into my basement lab—straight…

Cary CAD-1610-SE monoblock power amplifier Manufacturer's Comment

Manufacturer's Comment

Editor: Sounds like Jonathan Scull and his bride, Kathleen, had a big time with the Cary CAD-1610-SE amplifiers in the December issue. I bet the cha-cha-cha was not the only dance this musically inclined couple enjoyed while listening to the '1610s. I can just imagine Kathleen following J-10's galactic moves. Fortunately, this couple was not demoralized by John Atkinson's spectrum analyzer. Now that would have been silly!

In case you are wondering what the silly stuff is, go no further than the final parting shots by John Atkinson on his view of one of my…

In Search of the Perfect 300B Tube

In the last two years, the available choices in 300B output tubes for one's low-wattage single-ended power amplifier have become an embarrassment of riches. If we include the souped-up versions—which, in fact, deviate from the original 1930s Western Electric (WE) specifications—the number of 300Bs to choose from now includes about 15 different brands and types.

This calls for an evaluation. A few of the 300Bs examined here have been covered in subjective reviews in other magazines (Vacuum Tube Valley, Fall/Winter 1997, issue 8; and Glass Audio, March 1998, Vol.10 No.2), but the variety…

In Search of the Perfect 300B Tube Page 2

Now that we've discussed possible lurking hazards (life is never easy), let's take a look at the seductions posed by over-specified 300Bs. Some manufacturers imply that you get a higher power output from your amp when you install a high-dissipation 300B (eg, 18Wpc output instead of 9Wpc from a typical SE amplifier). This is not true. The amplifier would have to be redesigned to fully take advantage of a tube's higher maximum anode dissipation. The output generated is a strict function of the available power-supply voltage, the specified anode current, and the output transformer's impedance (…

In Search of the Perfect 300B Tube Page 3

If one is to give a reliable evaluation of a 300B, it is essential that the tube be burned in for an appreciable amount of time (footnote 4). One hundred hours are not enough; 200 hours seems to be a workable minimum (footnote 5). In doubtful cases, we added an extra 100 hours (see sidebar "A Tale of Burn-In"). If you count the number of tubes tested, including the backup pairs, and consider that we had three locations where burn-in could take place, and that eight hours of burn-in per day is a realistic figure (we avoided leaving the amps on unattended), you'll begin to realize the vast…

In Search of the Perfect 300B Tube Page 4

JJ Electronics 300B: $199/pair. As tall as the KR, but not quite as heavy. Gold wire is used for the grid, and the grid supports are supplied with cooling fins (unusual in a 300B). Worked well in both amps. Very good bass—real pressure there—but with a trace of "hollow" coloration in the midbass when used in the AudioNote. Very involving, even euphonic—almost as if trying to make things nicer than real. Quite open, but a very thin veil was noticeable that resulted in a subtle soft-focus effect. Good dynamics, reasonably fine detail, threw a remarkably wide stage with the AudioNote. Lost some…

In Search of the Perfect 300B Tube Contact Info

Sidebar 1: Contact Information

Svetlana Electron Devices: 3000 Alpine Road, Portola Valley, CA 94028. Tel: (650) 233-0429. Fax: (650) 233-0439. pbelov@svetlana.com

Western Electric Audio Products: 1230 Peachtree Street, Suite 3750, Atlanta, GA 30309-3575. Tel: (404) 874-4400. Fax: (404) 874-4415. sales@westernelectric.com

KR Enterprise SRO: Nadaemlejnska 1/600, 198 00 72 Prague 9, Czech Republic. Tel/fax: 011 420-2-83064168. krenterprise@serverpha.czcom.cz.

JJ Electronic: Valve Amplification Company, 807 Bacon Street, Durham, NC 27703. Tel: (919) 596-1107. Fax: (…

In Search of the Perfect 300B Tube Associated Equipment

Sidebar 2: Associated Equipment

The tube samples were listened to in two power amplifiers of different technology and performance levels. One was the ineluctable AudioNote Kit One, nearly unanimously seen as one of the best 300B amps around in DIY kit form. It features automatic bias (cathode resistors), a single power supply, and 78S05 filament regulators. Input and driver tubes had been replaced by superior NOS devices (New Old Stock: tubes produced 30 or more years ago but never used), as had a few coupling capacitors.

Source was a Marantz CD16 CD player (upgraded by Marantz…

In Search of the Perfect 300B Tube A Tale of Burn-In

Sidebar 3: A Tale of Burn-In

The following tale is instructive. The first two 300Bs Western Electric sent me were said to have had 200 hours of factory burn-in. They were not shipped directly to me but first to another reviewer, in the US. When they finally arrived, I gave 'em a few days' rest, then 50 hours of additional burn-in before listening. Still, they were disappointing. I had heard new-production WEs before, so I knew how good they could be. Fortunately, I discovered a friend with a well burned-in pair of WEs. We arranged a comparison, and the shipped pair was definitely…

In Search of the Perfect 300B Tube Followup

Sidebar 4: Followup from May 2000 issue of Stereophile

My survey of 300B power tubes last November (Vol.22 No.11, p.72.) was bad news for Svetlana, as four out of six samples of their 300B failed after 300-400 hours. Svetlana corrected a problem they had found and sent me four samples from the new production run. I installed these in two amplifiers and, to gain time, left them running day and night for 900 hours—nearly six weeks! To mimic real-use circumstances, each morning I switched the amps off to let the tubes cool down fully, then switched them on again, in order to expose the…