Re: SACRILEGE! NOS Bull*** Debunked...



Rich Koerner wrote:

> Lord Valve wrote:
> > Lord Valve Speaketh:
> >
> > I assembled a collection of NOS and current-production
> > 6L6s; these were all pulled from my inventory, and all
> > had passed my burn-in and GC procedures prior to being
> > matched on my proprietary matching rig at identical
> > test voltages. A measured plate current of 32 mA was
> > chosen as the value which could be most consistently pulled
> > from the available stock; when this was not possible
> > (twice) the nearest lower PC value was selected. This
> > was done to insure that the characteristics of the
> > tubes were as close as possible, as measured on my test
> > rig. 14 different quads were available for relative
> > power output testing.
> >
> > All 14 of the quads were tested in a 1974 SFTR,
> > master volume/pull boost type. All of the
> > electrolytics in the amp were replaced with
> > Sprague Atoms or Nichicons. The PI stage was
> > blackfaced, but the master volume control was
> > left in the circuit at the customer's request.
> > The screen and swamp resistors were all brand
> > new. Preamp tubes were four Reflektor/Tung-Sol
> > 12AX7s and two NOS Philips JAN 12AT7WC/6201s.
> >
> > Signals at seven different test frequencies were
> > run through the Normal channel, as the Vibrato
> > channel in pull-boost MV SF Twin Reverbs suffers
> > from asymmetrical clipping. Controls were set as
> > follows: Volume, 4; all tones, 10; MV full up,
> > no boost, no reverb, no tremolo. The filament
> > hum balance was tuned for minimum hum after the
> > controls were adjusted as above.
> >
> > A Raytheon/Sorenson model 500-S vacuum tube
> > AC line regulator was used to supply power to
> > the chassis. This is not a tap-switcher, and
> > it is highly accurate. AC line input to the
> > amp measured 122.60 VAC at idle, and 122.80
> > VAC at max output (measured just before soft
> > clipping at 100 Hz.)
> >
> > Plate voltage was 440.50 VDC, measured with
> > the tubes set for 18.5 watts static dissipation.
> > Each quad was biased to 18.5 watts static after
> > a 10-minute warmup period prior to power testing.
> >
> > All voltages were monitored with either Fluke
> > 189s or 187s. The signal generator was a Heath
> > IG-5218. The scope was a Leader LBO-310A. The
> > load resistor was a non-inductive Dale 250 watt
> > 4-ohm 1% mounted to a large heatsink with fan
> > cooling. Voltage across the resistor was monitored
> > with a Fluke 189, and rounded to the nearest .01
> > VAC RMS. The monitored voltage was squared and
> > the result was divided by the load resistance
> > to obtain the output power at the seven different
> > test frequencies. Measurement in each case was
> > taken after running the amp to a soft clip and
> > backing the output down until no flattening of the
> > peaks/troughs was detectable. The amp was allowed
> > to "settle" for one minute at each test frequency
> > after being adjusted as above prior to recording
> > the reading.
> >
> > Readings at the seven test frequencies were added
> > and then divided by the number of readings in order
> > to assign the tubes a "rank" as far as overall power
> > output is concerned. These tests were performed
> > in order to debunk the belief (currently held by
> > many people who ought to know better) that NOS 6L6s
> > will *always* produce superior power output in any
> > given situation. The highest-ranking NOS tube placed
> > fifth. Note that the top three are separated by only
> > a third of a watt in output; this is a dead heat as
> > far as I'm concerned. However, the highest beats the
> > lowest (both from the same company) by twenty watts,
> > and that *is* significant.
> >
> >
> > Read 'em and weep:
> >
> > 1) Reflektor/Svetlana 6L6GC -
> >
> > 100 Hz - 94.18 WRMS
> > 250 Hz - 92.83 WRMS
> > 500 Hz - 90.44 WRMS
> > 1.0 KHz - 90.25 WRMS
> > 2.5 KHz - 89.96 WRMS
> > 5.0 KHz - 89.02 WRMS
> > 10.0 KHz - 81.97 WRMS
> >
> > Average: 89.81
> >
> > 2) SED/Winged C 6L6GC -
> >
> > 100 Hz - 92.16 WRMS
> > 250 Hz - 90.82 WRMS
> > 500 Hz - 90.72 WRMS
> > 1.0 KHz - 90.25 WRMS
> > 2.5 KHz - 90.25 WRMS
> > 5.0 KHz - 89.40 WRMS
> > 10.0 KHz - 82.91 WRMS
> >
> > Average: 89.50
> >
> > 3) JJ/Tesla 6L6GC [1] -
> >
> > 100 Hz - 92.93 WRMS
> > 250 Hz - 91.58 WRMS
> > 500 Hz - 89.40 WRMS
> > 1.0 KHz - 91.48 WRMS
> > 2.5 KHz - 89.78 WRMS
> > 5.0 KHz - 89.30 WRMS
> > 10.0 KHz - 81.90 WRMS
> >
> > Average: 89.48
> >
> > 4) Shuguang 6L6GC-M brown base [2] -
> >
> > 100 Hz - 89.78 WRMS
> > 250 Hz - 89.11 WRMS
> > 500 Hz - 89.21 WRMS
> > 1.0 KHz - 88.80 WRMS
> > 2.5 KHz - 88.27 WRMS
> > 5.0 KHz - 87.04 WRMS
> > 10.0 KHz - 82.99 WRMS
> >
> > Average: 87.89
> >
> > 5) NOS RCA 6L6GC "blackplate" -
> >
> > 100 Hz - 88.08 WRMS
> > 250 Hz - 88.17 WRMS
> > 500 Hz - 89.21 WRMS
> > 1.0 KHz - 90.06 WRMS
> > 2.5 KHz - 89.02 WRMS
> > 5.0 KHz - 86.58 WRMS
> > 10.0 KHz - 76.56 WRMS
> >
> > Average: 86.81
> >
> > 6) NOS Philips 7581A [3] -
> >
> > 100 Hz - 90.25 WRMS
> > 250 Hz - 87.42 WRMS
> > 500 Hz - 85.19 WRMS
> > 1.0 KHz - 86.68 WRMS
> > 2.5 KHz - 85.66 WRMS
> > 5.0 KHz - 84.82 WRMS
> > 10.0 KHz - 79.30 WRMS
> >
> > Average: 85.62
> >
> > 7) Reflektor/Tung-Sol 5881 -
> >
> > 100 Hz - 87.42 WRMS
> > 250 Hz - 88.73 WRMS
> > 500 Hz - 86.12 WRMS
> > 1.0 KHz - 84.27 WRMS
> > 2.5 KHz - 84.00 WRMS
> > 5.0 KHz - 84.10 WRMS
> > 10.0 KHz - 81.14 WRMS
> >
> > Average: 85.11
> >
> > 8) NOS Sylvania/Mesa STR-415 [4] -
> >
> > 100 Hz - 85.56 WRMS
> > 250 Hz - 83.63 WRMS
> > 500 Hz - 84.46 WRMS
> > 1.0 KHz - 82.99 WRMS
> > 2.5 KHz - 84.00 WRMS
> > 5.0 KHz - 84.64 WRMS
> > 10.0 KHz - 79.34 WRMS
> >
> > Average: 83.52
> >
> > 9) NOS GE 6L6GC (clear top) -
> >
> > 100 Hz - 84.82 WRMS
> > 250 Hz - 83.54 WRMS
> > 500 Hz - 83.90 WRMS
> > 1.0 KHz - 85.19 WRMS
> > 2.5 KHz - 84.18 WRMS
> > 5.0 KHz - 82.81 WRMS
> > 10.0 KHz - 78.61 WRMS
> >
> > Average: 83.29
> >
> > 10) Shuguang/Valve-Arts 6L6GC -
> >
> > 100 Hz - 81.90 WRMS
> > 250 Hz - 81.90 WRMS
> > 500 Hz - 80.28 WRMS
> > 1.0 KHz - 81.00 WRMS
> > 2.5 KHz - 80.64 WRMS
> > 5.0 KHz - 78.06 WRMS
> > 10.0 KHz - 76.30 WRMS
> >
> > Average: 80.01
> >
> > 11) Shuguang/Ruby 6L6GCSTRM -
> >
> > 100 Hz - 83.45 WRMS
> > 250 Hz - 77.97 WRMS
> > 500 Hz - 80.28 WRMS
> > 1.0 KHz - 78.94 WRMS
> > 2.5 KHz - 76.65 WRMS
> > 5.0 KHz - 71.74 WRMS
> > 10.0 KHz - 68.06 WRMS
> >
> > Average: 76.73
> >
> > 12) Sovtek 6L6WXT -
> >
> > 100 Hz - 76.30 WRMS
> > 250 Hz - 76.74 WRMS
> > 500 Hz - 76.65 WRMS
> > 1.0 KHz - 76.56 WRMS
> > 2.5 KHz - 76.12 WRMS
> > 5.0 KHz - 76.13 WRMS
> > 10.0 KHz - 74.31 WRMS
> >
> > Average: 76.12
> >
> > 13) Shuguang/TAD 6L6WGC "shortbottle" -
> >
> > 100 Hz - 78.32 WRMS
> > 250 Hz - 76.60 WRMS
> > 500 Hz - 76.48 WRMS
> > 1.0 KHz - 74.40 WRMS
> > 2.5 KHz - 74.39 WRMS
> > 5.0 KHz - 74.56 WRMS
> > 10.0 KHz - 72.50 WRMS
> >
> > Average: 75.32
> >
> > 14) Sovtek 5881WXT -
> >
> > 100 Hz - 75.43 WRMS
> > 250 Hz - 73.36 WRMS
> > 500 Hz - 69.14 WRMS
> > 1.0 KHz - 70.73 WRMS
> > 2.5 KHz - 69.31 WRMS
> > 5.0 KHz - 68.95 WRMS
> > 10.0 KHz - 61.86 WRMS
> >
> > Average: 69.83
> >
> > Notes:
> >
> > [1] An 87K resistance (from a decade box) had to
> > be placed in parallel with the bias range
> > setting resistor in order to bias the JJ 6L6s
> > to 18.5 watts static; in actual operation, the
> > range setting resistor would be replaced with
> > a much lower value than the parallel network
> > used in this test, as the bias control was at
> > the lowest negative voltage it could produce
> > when the shunt resistance was applied. This
> > is a common problem with this particular JJ tube.
> >
> > [2] This is the least expensive tube in the group.
> >
> > [3] This is the most expensive tube in the group.
> >
> > [4] The Mesa STR-415 was a custom selection from the
> > Sylvania STR-387/6L6GC production; it was picked
> > to be within Mesa's bias range.
> >
> > An interesting side note: it was recently reported on
> > AGA that the base on the Reflektor/Svetlana 6L6GC was
> > too small to fit correctly into Fender-style beartrap
> > clamps. This is nonsense. This tube's base is in fact
> > 1/32" greater in diameter than the JJ 6L6GC's, and no
> > reports of JJs not fitting into Fender clamps have been
> > seen. The Reflektor/Svet's base is the same size as that
> > used on the Reflektor/Tung-Sol 5881, which is slightly
> > larger in diameter than the original Tung-Sol 5881's -
> > which also fit comfortably into standard Fender clamps.
> > ALL of the bases discussed above were originally built
> > for EL34s, as they are exactly the same size as the bases
> > used on the respective companies' EL34 tubes. Which,
> > BTW, *also* fit into Fender clamps with no difficulty.
> >
> > Mullard Mullahs, Philips Philistines, GE Jihadis, RCA
> > Ankle Nippers (woof!), Telefunken Tyrants, Siemens
> > Snobs, Amperex Avengers and other various and sundry
> > NOS hardliners may now commence shucking and jiving
> > in a vain attempt to impeach the test results.
> >
> > Good luck.
> >
> >
> > Lord Valve
> > Expert
> >
> >
> > VISIT MY WEBSITE: http://www.nebsnow.com/LordValve
> > I specialize in top quality HAND SELECTED NOS and
> > current-production vacuum tubes for guitar and
> > bass amps. Good prices, fast service.
> > Authorized dealer for QSC amps, Sovtek/Electro-Harmonix,
> > Behringer, Hammond-Suzuki, Leslie, Rolls, many more!
> >
> > - Partial Client List -
> > * Derek Trucks (Allman Brothers Band/Derek Trucks Band) *
> > * Meatloaf * Catherine Wheel * Yo La Tengo * Let's Go Bowling *
> > * Kofi Burbridge (DTB) * Tod Smallie (DTB) * Susan Tedeschi *
> > * Roy Pritts (former head, Audio Engineering Society) *
> > * Rob Hyckys (guitarist for Commander Cody) * Waky Amps *
> > * Jamie McLean (guitarist for the Dirty Dozen Brass Band) *
> > * Coco Montoya * Clint Black * Bill McKay * John Denver * *** Dale *
> > * Fleetwood Mac * Tyrin Benoit * Eugene Fodor * Dale Bruning *
> > * Komet Amplification * Dr. Z * Maven Peal * Blockhead Amps *
> > * Jim Kelley * Balls Amplification * Roccaforte Amplifiers *
> > * Gerhart Amplification * Aiken Amplification * The Right Half of AGA *
> > * Ed Blum * Ken Wilson * Lots More *
> >
> > NBS Electronics, 230 South Broadway, Denver, CO 80209-1510
> > Phone orders/tech support after 1:30 PM Denver time at 303-778-1156
> >
> > - Our 24th Year -
> >
> > VISA - MASTERCARD - PAYPAL - DISCOVER
> >
> > Philo T. Farnsworth sez, "Vacuum tubes kick major ass.
> > Be a MAN...and buy some TODAY!"
> >
>
> Your test bed is not even close to the max spec of the NOS, nor does your test bed
> approach them.
>
> For example, the nos GE's are not even turned on yet with your 18. watts static
> dissipation.
>
> TRY 30 Watts plate dissipation as the setting, and run them at a plate voltage of
> 550 VDC in Ultra Linear configuration for example.
>
> All you did was select a test bed that is friendly to the polished turds, for a
> momentary test.
>
> Use a 400-PS for the test bed, and you will be doing something of substance by
> presenting an extreme testing environment.
>
> Then run them till they croak. Then, post the postmortems.
>
> I'm interested in your power rating at 100 hz, with a 50 Hz added after each 100
> hours of continuous full tilt boogie dynamic testing.
>
> Don't worry about the 400-PS crapping out as a test bed either.
>
> <Hell, if you ain't got a 400, throw them in an SVT.>
>
> You didn't even STRESS those SELECTED tubes worth a ***.
>
> Like I said long ago in here,.... when I find a polished turd that ain't a
> polished turd, I'll let you know.
>
> Post the postmortems from extreme dynamic testing.
>
> THAT, is the bottom line here.

Irrelevant. People don't run those tubes in your situation.

Keep dancing. Next?

LV




.

Quantcast