Hi there!
Need your advice. Can two matched pairs of el84 from the same tube batch (Sovtek) be used in power-amp of AD30? Which is the correct way to install theM: 1-2-2-1 or 1-2-1-2 ?
Thank you!!!
P.S. I've ordered a quad beforehand, but the delivery got stuck for much longer time, than expected, and I've got concert tomorrow (
Two Matched PAIRS instead of matched QUAD in AD30
Moderator: bclaire
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- Duke of Orange
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Re: Two Matched PAIRS instead of matched QUAD in AD30
How big is the mismatch between the matched pairs?
In any case, I think you will be fine, but would recommend your approach re: 1221 / 1212.
I think it's the first config, but wait for confirmation from someone else.
In any case, I think you will be fine, but would recommend your approach re: 1221 / 1212.
I think it's the first config, but wait for confirmation from someone else.
Ant
Orange Gear: RV50 MKI, R30, AD15, PPC212
And.... Genz Benz Black Pearl 30
Past Orange: AD30TC Combo, TT, AD5
Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute
Orange Gear: RV50 MKI, R30, AD15, PPC212
And.... Genz Benz Black Pearl 30
Past Orange: AD30TC Combo, TT, AD5
Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute
Re: Two Matched PAIRS instead of matched QUAD in AD30
Either is good. Good idea to label the pairs to avoid confusion.Les Paul Lover wrote: ↑Wed Oct 18, 2017 10:42 amHow big is the mismatch between the matched pairs?
In any case, I think you will be fine, but would recommend your approach re: 1221 / 1212.
I think it's the first config, but wait for confirmation from someone else.
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- Duke of Orange
- Posts: 6821
- Joined: Tue Aug 18, 2009 9:08 am
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Re: Two Matched PAIRS instead of matched QUAD in AD30
Is the cathode bias done on each individual valve or by pair?Jondog wrote: ↑Wed Oct 18, 2017 11:44 amEither is good. Good idea to label the pairs to avoid confusion.Les Paul Lover wrote: ↑Wed Oct 18, 2017 10:42 amHow big is the mismatch between the matched pairs?
In any case, I think you will be fine, but would recommend your approach re: 1221 / 1212.
I think it's the first config, but wait for confirmation from someone else.
Ant
Orange Gear: RV50 MKI, R30, AD15, PPC212
And.... Genz Benz Black Pearl 30
Past Orange: AD30TC Combo, TT, AD5
Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute
Orange Gear: RV50 MKI, R30, AD15, PPC212
And.... Genz Benz Black Pearl 30
Past Orange: AD30TC Combo, TT, AD5
Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute
Re: Two Matched PAIRS instead of matched QUAD in AD30
PairLes Paul Lover wrote: ↑Wed Oct 18, 2017 12:17 pmIs the cathode bias done on each individual valve or by pair?Jondog wrote: ↑Wed Oct 18, 2017 11:44 amEither is good. Good idea to label the pairs to avoid confusion.Les Paul Lover wrote: ↑Wed Oct 18, 2017 10:42 amHow big is the mismatch between the matched pairs?
In any case, I think you will be fine, but would recommend your approach re: 1221 / 1212.
I think it's the first config, but wait for confirmation from someone else.
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Re: Two Matched PAIRS instead of matched QUAD in AD30
No bias adjustment necessary.
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- Orange Master
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Re: Two Matched PAIRS instead of matched QUAD in AD30
If the mismatch is large enough, the pair drawing more current could self destruct and see a premature death. But if the pairs are in the same ball park you're probably fine. Look for any visible red plating in low light and if you don't see any, you're probably ok to run them.
Mind you, a quad of EL-84s is pretty cheap, and the AD30 has pretty low headroom to begin with. I think you'd be best served by getting a matched quad in there.
Mind you, a quad of EL-84s is pretty cheap, and the AD30 has pretty low headroom to begin with. I think you'd be best served by getting a matched quad in there.
'71 GRO100 || '96 OR-80 || AD30 || '64 AC-50 || AC-30TBX || Hiwatt DR504 || HI-TONE HT30
LP Standard || LP Studio || LP Custom Lite || Ric 620 || Ric 360 || MIA Tele || SG 61 RI
Re: Two Matched PAIRS instead of matched QUAD in AD30
The seller says that the tubes are from one factory batch and the difference wouldn't be too big. Sure, a match quad is the normal solution. As I said, I've ordered a quad beforehand, but the delivery got stuck, so I was in search of temporary option (ALL quads are sold out in the city LOL).fiveightandten wrote: ↑Wed Oct 18, 2017 10:17 pmIf the mismatch is large enough, the pair drawing more current could self destruct and see a premature death. But if the pairs are in the same ball park you're probably fine. Look for any visible red plating in low light and if you don't see any, you're probably ok to run them.
Mind you, a quad of EL-84s is pretty cheap, and the AD30 has pretty low headroom to begin with. I think you'd be best served by getting a matched quad in there.
Thank you all very much for response!! I've found the main board schematics, according to this which would be appropriate pair placement?
http://www.prowessamplifiers.com/schema ... board.html
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- Duke of Orange
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Re: Two Matched PAIRS instead of matched QUAD in AD30
2 things:
1) if valves coming from the same manufacturing batch were all in the same ballpark, we wouldn't have the issues with valve matching we have these days. Are the pairs you have actually graded?
2) from the schematic, it looks like 1122 arrangement. I'd like to see the PCB to confirm though. I think the cathode resistor (fixed bias) is linked to pin 3 on EL84, and here R29 is connected to V4 & V5, R33 to V6 and V7. Wait for someone else to confirm though, I'm very much a hack.
1) if valves coming from the same manufacturing batch were all in the same ballpark, we wouldn't have the issues with valve matching we have these days. Are the pairs you have actually graded?
2) from the schematic, it looks like 1122 arrangement. I'd like to see the PCB to confirm though. I think the cathode resistor (fixed bias) is linked to pin 3 on EL84, and here R29 is connected to V4 & V5, R33 to V6 and V7. Wait for someone else to confirm though, I'm very much a hack.
Ant
Orange Gear: RV50 MKI, R30, AD15, PPC212
And.... Genz Benz Black Pearl 30
Past Orange: AD30TC Combo, TT, AD5
Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute
Orange Gear: RV50 MKI, R30, AD15, PPC212
And.... Genz Benz Black Pearl 30
Past Orange: AD30TC Combo, TT, AD5
Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute
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- Orange Master
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- Joined: Sat Apr 05, 2003 6:18 pm
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Re: Two Matched PAIRS instead of matched QUAD in AD30
The right pair is grounded together and the left pair is grounded together. 1221 or 1212. Check for any visible red plating in low light while playing at the volume you will be playing at.ArtyArson wrote: ↑Thu Oct 19, 2017 8:02 amThe seller says that the tubes are from one factory batch and the difference wouldn't be too big. Sure, a match quad is the normal solution. As I said, I've ordered a quad beforehand, but the delivery got stuck, so I was in search of temporary option (ALL quads are sold out in the city LOL).fiveightandten wrote: ↑Wed Oct 18, 2017 10:17 pmIf the mismatch is large enough, the pair drawing more current could self destruct and see a premature death. But if the pairs are in the same ball park you're probably fine. Look for any visible red plating in low light and if you don't see any, you're probably ok to run them.
Mind you, a quad of EL-84s is pretty cheap, and the AD30 has pretty low headroom to begin with. I think you'd be best served by getting a matched quad in there.
Thank you all very much for response!! I've found the main board schematics, according to this which would be appropriate pair placement?
http://www.prowessamplifiers.com/schema ... board.html
'71 GRO100 || '96 OR-80 || AD30 || '64 AC-50 || AC-30TBX || Hiwatt DR504 || HI-TONE HT30
LP Standard || LP Studio || LP Custom Lite || Ric 620 || Ric 360 || MIA Tele || SG 61 RI
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