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Post by Beckanon on Feb 7, 2006 17:56:53 GMT -7
Wow! My 66 sounded good before, but now it sounds absolutely great. As mentioned on these 66 threads before, optimum tube choice can make a difference...and, of course, beauty is in the ear of the listener. I got a matched pair of Shuguang KT66s and the box they came in from KCA had "30" marked as matching current. Is this still considered cold for a Rt.66? Well, so far, without any amp rebiasing I think they sound fantastic as is. Giving it up sooner than my previous Russian set. Plus I think the Chinese set has better high-mid to treble response. The kicker is this GEC EF86 tube. Geeez, you guys weren't kidding! Adds more of a 3D dimension, more stringiness, more of my guitar's (tele) wood and electronics. Much more touch sensitive. I can't wait for the weekend gigs! ;D
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Post by Laroosco!! on Feb 8, 2006 0:46:13 GMT -7
My last 66 had Shuguangs in it and they sounded great!! I really prefered them to the GT's.
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Post by Beckanon on Feb 9, 2006 14:13:46 GMT -7
I'm feeling/hearing some pretty sweet amp compression going on too...again, better than what it was before (and before wasn't bad either). Notes, even clean sounds, sustain better. Plus there used to be some borderline deadspots around the 12th fret area on my tele -- GONE.
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Post by rickbob on Feb 10, 2006 16:02:14 GMT -7
I've got 'em in my 66 as well, yeah real nice. I bought a quad so i'd have a backup pair, also if i remember right these aren't being made anymore, but Lord Valve and Mike at KCA probably have a pretty good stockpile, i got mine from L.V. Bet that GEC 86 is sweet, i've got a couple Mulllards, a Tele, some others that were given to me, and a Dario from KCA that's in there now.....
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Post by myles on Feb 10, 2006 17:01:04 GMT -7
Wow! My 66 sounded good before, but now it sounds absolutely great. As mentioned on these 66 threads before, optimum tube choice can make a difference...and, of course, beauty is in the ear of the listener. I got a matched pair of Shuguang KT66s and the box they came in from KCA had "30" marked as matching current. Is this still considered cold for a Rt.66? Well, so far, without any amp rebiasing I think they sound fantastic as is. Giving it up sooner than my previous Russian set. Plus I think the Chinese set has better high-mid to treble response. The kicker is this GEC EF86 tube. Geeez, you guys weren't kidding! Adds more of a 3D dimension, more stringiness, more of my guitar's (tele) wood and electronics. Much more touch sensitive. I can't wait for the weekend gigs! ;D The "30" number may be the test current but it really means nothing as we do not know what plate voltage and bias the test rig was set for. Be careful with the Shuguang KT66 as they can fail without warning above 450 plate volts in some amps if the screen voltage is also high. The KT66HP (the stock tube) runs at 525v and beyond.
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Post by Beckanon on Feb 10, 2006 17:18:10 GMT -7
Okay... I'll try these chinese KT's for the gigs this weekend and bring the Saratovs as backup. Probably what I should do is put the Russian tubes back in and see how they get on with the EF86. Plus, after reading your PI article Myles, I want to also try some options in that slot as well.
The more I play with the Shuguangs in there, I think I perceive a drop in headroom and overall volume (albeit small). My attenuator settings are much higher now...and even playing with the attn. bypassed sounds not too loud. The gigs will help spell this out too.
It's the increased sustain, chewiness and bounce that I really am enjoying right now. Is this more a function of the EF86, as opposed to the output tubes?
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Post by myles on Feb 10, 2006 18:27:57 GMT -7
Okay... I'll try these chinese KT's for the gigs this weekend and bring the Saratovs as backup. Probably what I should do is put the Russian tubes back in and see how they get on with the EF86. Plus, after reading your PI article Myles, I want to also try some options in that slot as well. The more I play with the Shuguangs in there, I think I perceive a drop in headroom and overall volume (albeit small). My attenuator settings are much higher now...and even playing with the attn. bypassed sounds not too loud. The gigs will help spell this out too. It's the increased sustain, chewiness and bounce that I really am enjoying right now. Is this more a function of the EF86, as opposed to the output tubes? A lot of the sustain ... when you do not have it across the fretboard, is output match. Once the tubes are farther than 20% they are not really usable. I always go for less than 10% (at 30mA I can go as far 33 on one tube if the other is 30mA. I can also go down to 27mA or so). But .... for my clients amps, 5% is about the most and typically the tubes are better than < 1.0mA apart. On the curve tracer they have to be dead on across the board when they are running. Static match is not too critical until the tubes are far enough out from each other to cause hum. But that is only true if their dynamic match is on the money. It is sort of like ..... I can set the idle on my Scion at 750 RPM and then set it the same on a BMW M5. The idle is matched but under operating conditions the cars are no where alike. You could also have a phase inverter that is weak. I find this very very often.
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Post by rickbob on Feb 10, 2006 23:56:14 GMT -7
Be careful with the Shuguang KT66 as they can fail without warning above 450 plate volts in some amps if the screen voltage is also high. The KT66HP (the stock tube) runs at 525v and beyond. Myles 450 is where mine is running on the plate voltage, and where Dr. Z recomends to run a 66 if you set bias off of the plate voltage, so to speak (i'm not fluent in these terms per se, just what i've picked up, i bias with a Weber bias-rite with VI option for reading plate voltage....). That is running @ 36-37 ma on my tubes/amp fwiw, and with a healthy old rectifier tube, GT matched PI (2-3 yrs old PI to be fair, but it balances both sides to within a couple ticks of 450). Considering that, do you think my screen voltage would be in a 'safe' range for the Shugaung's?
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Post by Beckanon on Feb 12, 2006 14:43:47 GMT -7
Okay, here's some results from this past weekend.
I went into Friday night with the Shuguang KT66 and GEC EF86 installed...I loved this setup at home. The breakup came sooner and was dynamic, sweet, musical, etc.
Midway into our first set I figured out that this setup wasn't cutting it as far as headroom was concerned. Sounded good, but I ended up turning off my attenuator and had to turn up my Rt66 just to be heard (7 piece band with keys and 2 horn players). This made me a bit uncomfortable.
On the set break I started swapping and testing (much to the chagrin of the bar patrons, I'm sure! ;D). I ended up playing the rest of the night and Saturday with the Shuguangs and the original EF86 (sovtek? not sure) that was in there.
So, I'm not really sure what's going on....my next priorities are to actually bias this amp and to also look into a new PI tube, after reading that article (thanks, Myles). Anyway, I was very happy with the sound Saturday night...I pushed the amp with the ZVex Super Duper and it sounded great. I may be one of those players that needs the extra headroom on my Rt66.
The tweeking will continue. I want to get maybe a few PI tubes to mess with and see how the GEC EF86 behaves with those.
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Post by myles on Feb 14, 2006 12:50:49 GMT -7
Be careful with the Shuguang KT66 as they can fail without warning above 450 plate volts in some amps if the screen voltage is also high. The KT66HP (the stock tube) runs at 525v and beyond. Myles 450 is where mine is running on the plate voltage, and where Dr. Z recomends to run a 66 if you set bias off of the plate voltage, so to speak (i'm not fluent in these terms per se, just what i've picked up, i bias with a Weber bias-rite with VI option for reading plate voltage....). That is running @ 36-37 ma on my tubes/amp fwiw, and with a healthy old rectifier tube, GT matched PI (2-3 yrs old PI to be fair, but it balances both sides to within a couple ticks of 450). Considering that, do you think my screen voltage would be in a 'safe' range for the Shugaung's? I'd use this: 450 V 25 W 40% 50% 60% 70% 22 28 33 39 Or about 32-34mA when biased at a 25 watt tube. The HPs are 30 watters but I prefer the 25 watt spec on the Shuguangs. You are actually safe with your settings but the amp may sound a little less harsh at a 32-34 setting.
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Post by rickbob on Feb 14, 2006 20:20:23 GMT -7
Thanks Myles. Yeah i like it sounding a little gnarly i guess, i've always biased it in the 36+ range.... As far as the plate voltage i said "the Dr. recommends 450 plate volts" i should be more clear....that's my rough interpretation/guess, he'd suggested @475 on his web page i believe, but then discovered the extra stiff voltage in his shop power so my interpretation/guesstimation for an average players' wall voltage was to drop to around 450 plate....i'm just happy to get get in and out of my chassis in one piece when i bias (with my Weber Bias-Rite's help!) so what do i know........my 66 is out on a long term loan right now so we'll see how the Shug's hold up!.....
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Post by myles on Feb 22, 2006 11:16:08 GMT -7
Thanks Myles. Yeah i like it sounding a little gnarly i guess, i've always biased it in the 36+ range.... As far as the plate voltage i said "the Dr. recommends 450 plate volts" i should be more clear....that's my rough interpretation/guess, he'd suggested @475 on his web page i believe, but then discovered the extra stiff voltage in his shop power so my interpretation/guesstimation for an average players' wall voltage was to drop to around 450 plate....i'm just happy to get get in and out of my chassis in one piece when i bias (with my Weber Bias-Rite's help!) so what do i know........my 66 is out on a long term loan right now so we'll see how the Shug's hold up!..... I do not adjust bias to drop the plate voltage to the point of where the plate voltage is supposed to be. I do measure plate voltage (off pin 3 of the output tube) and then bias at 50-60% ID for the particular tube and work around that figure.
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wired
New Member
Posts: 2
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Post by wired on May 31, 2006 7:19:45 GMT -7
What's the ID stand for in the last thread dealing with bias. Thanks. John
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