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Post by DRZ on Jul 25, 2015 4:56:27 GMT -7
I received a request/order for two M-12's from Steve Miller. Steve needed a rig for a NYC project at Lincoln Center. Steve loves his StangRay sets ( 8 years and counting on the road ) and wanted a lower powered SR , same drive and punch but way less wattage/volume.
So I modded a standard M-12 it came out great, here's what I did. 1) Install a Chinese 5AR4 rectifier. 2) Rebias by replacing 180 Ohm 10 watt bias resistor with a 150 Ohm 10 watt resistor. 3) Replace JJ EL-84's with Low wattage JJ-EL-844 ( request Medium Range Matched set ).
There you go, a nice tonal upgrade and the EL-844's bring the volume down but the 5AR4 brings the tone and drive up. You can leave the JJ-EL-84's in place and have a M-20 then, I would swap out the EH-EL -84's if they came stock . Amps with EH's were built during the JJ tube rattle fiasco.
To help replicate the StangRays overall sound, I built Steve a 1X10 Combo loaded with a Celestion 10" Gold, and a 1X12 combo loaded with a 12" Gold.
DR.Z
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Post by KeithA on Jul 25, 2015 5:12:32 GMT -7
Sweet One of these sounds like a great match for the Z--Wreck set. You should make one of these available in the same cabinet as the silver Z-Verb and call it the 'X-Ray'
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Post by smolder on Jul 25, 2015 5:46:03 GMT -7
That's pretty awesome.
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Post by Mark (Basement Enthusiast) on Jul 25, 2015 8:02:02 GMT -7
Sweet, thanks for publishing your "secrets," Doc! Just curious, why the Chinese recto, specifically? Something different about those than the European Sovteks or JJ's?
OK, so here's how I understand it: the 5AR4 brings the output up, EL-844's bring it down, and the 150 Ω resistor re-biases for the EL-844's. I think we can deduce, then, that the overall change from a stock M-12 to a "lower-powered StangRay" is the more immediate feel/attack of the 5AR4. And I bet the Gold is a big part of the sound, too.
Methinks a "mod" switch might be called for, perhaps, on the bias resistor (?). Mode 1, standard tubes, gives you a standard M12; Mode 2, EL-844's & the 5AR4, gives the SR Jr. (This makes me think of Mike's prototype Antidote.)
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Post by Deleted on Jul 25, 2015 8:17:21 GMT -7
Very cool--gotta give the tube-swap part a try. Thanks, Doc!
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Post by Jaguarguy (Mike) on Jul 25, 2015 9:16:44 GMT -7
Sounds like a great low-cost mod!
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Post by Deleted on Jul 25, 2015 15:31:43 GMT -7
Hey Doc--can I send my M12 in for the resistor mod?
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Post by Deleted on Jul 27, 2015 12:12:54 GMT -7
Is it just the rectifier tube swap that increases wattage? I'm very interested in this amp, and even more interested if you can alter wattage by swapping the rectifier tube..
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Post by Jefferson on Jul 27, 2015 12:26:06 GMT -7
M12 is a killer, killer amp just like it is!
Now, with these potential changes, it may become even more "killer-er"!
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Post by Mark (Basement Enthusiast) on Jul 27, 2015 12:41:00 GMT -7
Is it just the rectifier tube swap that increases wattage? I'm very interested in this amp, and even more interested if you can alter wattage by swapping the rectifier tube.. That's what it sounds like it to me... Doc says, "the 5AR4 brings the tone and drive up. You can leave the JJ-EL-84's in place and have a M-20 then, I would swap out the EH-EL -84's if they came stock."So what I think he's saying is that if you put in the 5AR4 rectifier (only, with no other mods), you'll now have an approx. ~20 W amp. However, I think he also means that you'll burn up your regular EL-84 power tubes if you're using E-H brand (or anything other than JJ's); the JJ EL-84's are a little more stout and can handle the higher stress. It seems to me that his 2 other changes (reduced-power EL-844 tubes & re-biasing to accommodate those tubes) were done to counteract the increased power of using the 5AR4--so you don't need that if you want a higher-powered M-12. Make sense? Again... these are my understanding of the mods as presented by Doc; when in doubt, ask the big man himself.
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Post by Jefferson on Jul 27, 2015 13:30:52 GMT -7
hey doc, how does this change effect the use of pedals in front of the amp? is it still as pedal friendly?
thanks for your response in advance!
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Post by DRZ on Jul 27, 2015 16:25:32 GMT -7
hey doc, how does this change effect the use of pedals in front of the amp? is it still as pedal friendly? thanks for your response in advance! Still as pedal friendly . The EF 86 makes sure of that.
Z
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Post by Jefferson on Jul 27, 2015 18:54:48 GMT -7
Thanks doc! Any chance that you could get some sound samples up on this?
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Post by smolder on Jul 27, 2015 21:12:03 GMT -7
Doc - have you looked at or compared the EL844 vs the EL86 / 6CW5?
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Post by jesslm02 on Jul 27, 2015 22:17:57 GMT -7
So JJs are doing much better now? I retubed my Ghia with some last week and so far they are doing great and sound great. Definitely my favorite tube in the Ghia.
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Post by DRZ on Jul 28, 2015 3:57:59 GMT -7
Doc - have you looked at or compared the EL844 vs the EL86 / 6CW5? No, either are very commonly available for production usage.
Z
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Post by jimiata on Jul 29, 2015 7:12:56 GMT -7
Just so I understand this…..by using JJ tubes and changing to a 5AR4 rectifier and using a Celestion Gold speaker I now have around 20 watts?
Jim
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Post by jesslm02 on Jul 29, 2015 7:24:05 GMT -7
Just so I understand this…..by using JJ tubes and changing to a 5AR4 rectifier and using a Celestion Gold speaker I now have around 20 watts? Jim That's how I understood it as well.
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Post by DRZ on Jul 29, 2015 8:05:52 GMT -7
Just so I understand this…..by using JJ tubes and changing to a 5AR4 rectifier and using a Celestion Gold speaker I now have around 20 watts? Jim That's how I understood it as well. And re-bias with a 150 ohm 10 watt bias resistor.
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Post by jimiata on Jul 29, 2015 10:33:49 GMT -7
Thanks Doc, I thought it was too easy. So to get full pop with the JJ EL84 tubes, 5AR4 rectifier, Celestion Gold I must re-bias. What kind of wattage would I get with the JJ EL844 tubes?
Jim
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Post by DRZ on Jul 29, 2015 10:41:58 GMT -7
Thanks Doc, I thought it was too easy. So to get full pop with the JJ EL84 tubes, 5AR4 rectifier, Celestion Gold I must re-bias. What kind of wattage would I get with the JJ EL844 tubes? Jim Very close to a single ended EL-84 amp Appox. 8 watts. Z
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Post by jimiata on Jul 29, 2015 11:49:28 GMT -7
Thanks Doc, I'll try the re-bias resister.
Jim
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valvulator
New Member
M12 + LP R8 = Tone Bliss
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Post by valvulator on Jul 30, 2015 12:35:34 GMT -7
Just when I thought I had the baddest M 12 in town, it's mod time. Got to get some more silver solder.... BIG plus it's an easy to reverse mod! Thanks Dr for the info!!!
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Post by smolder on Jul 30, 2015 17:25:31 GMT -7
So that I understand this right... Those changes allow for a stronger EL84 20 watts, or a pair of EL844 for 8 watts?
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Post by DRZ on Jul 31, 2015 4:01:29 GMT -7
So that I understand this right... Those changes allow for a stronger EL84 20 watts, or a pair of EL844 for 8 watts? For all practical purposes, yes.
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Post by smolder on Jul 31, 2015 5:34:31 GMT -7
Thanks doc, that's pretty awesome. As spread out as that board is, I'm thinkin a guy could put a 150 and a 30 ohm in parallel with a toggle and have the best of all worlds... Though I might be over thinking it.
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Post by DRZ on Jul 31, 2015 8:04:39 GMT -7
Thanks doc, that's pretty awesome. As spread out as that board is, I'm thinkin a guy could put a 150 and a 30 ohm in parallel with a toggle and have the best of all worlds... Though I might be over thinking it. Series connect 150 plus 30 through a toggle , not parallel .
Z
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Post by smolder on Jul 31, 2015 9:29:28 GMT -7
Thanks doc, that's pretty awesome. As spread out as that board is, I'm thinkin a guy could put a 150 and a 30 ohm in parallel with a toggle and have the best of all worlds... Though I might be over thinking it. Series connect 150 plus 30 through a toggle , not parallel .
Z
Doh... They're big round and only look like a capacitor. Thanks for that ; )
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Post by JoeMo' on Aug 2, 2015 6:12:05 GMT -7
I received a request/order for two M-12's from Steve Miller. Steve needed a rig for a NYC project at Lincoln Center. Steve loves his StangRay sets ( 8 years and counting on the road ) and wanted a lower powered SR , same drive and punch but way less wattage/volume.
So I modded a standard M-12 it came out great, here's what I did. 1) Install a Chinese 5AR4 rectifier. 2) Rebias by replacing 180 Ohm 10 watt bias resistor with a 150 Ohm 10 watt resistor. 3) Replace JJ EL-84's with Low wattage JJ-EL-844 ( request Medium Range Matched set ).
There you go, a nice tonal upgrade and the EL-844's bring the volume down but the 5AR4 brings the tone and drive up. You can leave the JJ-EL-84's in place and have a M-20 then, I would swap out the EH-EL -84's if they came stock . Amps with EH's were built during the JJ tube rattle fiasco.
To help replicate the StangRays overall sound, I built Steve a 1X10 Combo loaded with a Celestion 10" Gold, and a 1X12 combo loaded with a 12" Gold.
DR.Z Would this work w a Zwreck?
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Post by jesslm02 on Aug 3, 2015 7:19:05 GMT -7
I received a request/order for two M-12's from Steve Miller. Steve needed a rig for a NYC project at Lincoln Center. Steve loves his StangRay sets ( 8 years and counting on the road ) and wanted a lower powered SR , same drive and punch but way less wattage/volume.
So I modded a standard M-12 it came out great, here's what I did. 1) Install a Chinese 5AR4 rectifier. 2) Rebias by replacing 180 Ohm 10 watt bias resistor with a 150 Ohm 10 watt resistor. 3) Replace JJ EL-84's with Low wattage JJ-EL-844 ( request Medium Range Matched set ).
There you go, a nice tonal upgrade and the EL-844's bring the volume down but the 5AR4 brings the tone and drive up. You can leave the JJ-EL-84's in place and have a M-20 then, I would swap out the EH-EL -84's if they came stock . Amps with EH's were built during the JJ tube rattle fiasco.
To help replicate the StangRays overall sound, I built Steve a 1X10 Combo loaded with a Celestion 10" Gold, and a 1X12 combo loaded with a 12" Gold.
DR.Z Would this work w a Zwreck? Seems like I remember a post where someone used the el844 tubes in the Zwreck to get a lower output volume. I'm pretty sure he didn't do any re-biasing though.
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