The Amp Design Process
DriftingByTheStorm
Posts: 8,684
So, I've been gabbing with Rob Franklin of FabAmps about picking up one of his FabFox 5\2watt switchable tube amps ...
I was maybe looking for input from anyone ... maybe regarding a EL84 vs 6V6 tube specificaly, or if you want to chime in on what you think i should do for tolex and a cloth color, thats cool too. Or if you just want to tell me to fuck off, I'm ok with that as well.
Here is a set of emails, going in reverse chronilogical order (ie. the first email is Robs last response):
Nice to hear back from you. I'll try point form for your questions->
How to proceed/Order confirmation.
Orders are confirmed by payment.
Payment methods are,
Money Wire, direct from your bank account to my business account.
International Money Order like those sold by the USPS
or a Cashiers Check
I prefer bank wire, no waiting for the mail. For the MO or CC, Priority Mail seems to work OK.
Speaker Selection
I can make the amp with two speaker outs and a 4/8 ohm switch. When you use one cab have the switch on 8. When you use two just switch to 4ohms. Will be no prob if your speakers are all 8 ohm.
Preamp
The Splexi has nice Vintage tone. The Metalhead is right over the wall though. Definitely more gain than a SLP. It is so versatile with the new Sweep knob, everything form thick creamy smooth distortion to tight articulate individual note definition, all within one knob when the gain is up.The tone stack is pretty amazing. Marshall TMK invented the Sweep knob but only used it on one older design. Krank(LOL) picked it up but not too many others, great knob. Amazing enough the amp can still get blues like cleans, sorta Fenderish when the gain is down. It really cleans up well with the guitar volume, something a lot of folks like. Takes pedals well too so it is also good for 80s tones. I am a 70s guy though and this amp easily dials in Sabbath but also ZZTop, Zepplin, Niel Young, early EVH...with the right pedal it does Boston to Beck. Very playable, every time I build one I have a great time testing it for sure. It does get that controlled feedback and when driven can really be full of harmonics. It's not the power so much as the gain for what you are after. You also could switch up to 5 watts, 2 watts is the low power setting. Simply a great preamp. Less buzz than the Marshall and a bit more gain. Honestly a few clients of mine do not use OD pedals after they found the gain and tone inside the Metalhead. Nuff said, IMO the Metalhead is an ear opener so I would highly suggest that for you.
EL84/6V6
The EL84 is the standard for a small British style amp. That said thought the 6V6 is a sturdier tube. With true Class A, especially in triode mode(low power), the differences I have found to be slight at best. Lately a few companies have been focusing on 6V6 designs. I think they get a bad rap and are very capable of great tone in the right design. Unless you are in love with EL84 try the 6V6, you will be surprised to find most of the tone originates in the preamp design. Its how hard the preamp hits the poweramp that creates the best tones for rock. With a Metalhead in front you will not have to worry about tone...
Don't know how high the yellow jacket is but yes plug and play. If it fits well it should work for the EL84 but I don't think you'll need to play around with a Metalhead Fox. All the tone you need is built in, just plug and play. Years of me playing around with Marshall designs has already been implemented.
The 5751
IMO the tube will lower the gain BUT will not add headroom. The same effect would come from lowering the Gain knob if it is in the front end of the amp or lowering the Master if it is in the PI/driver stage. I guess that would be OK in an amp that did not have one of those knobs. That said any 5751 is a super quality tube, MIL spec originally and will work in any 12ax7 stage. I don't know about the re-issues but the tone and noise of NOS brands was great. Another tube is the 7025, same gain as the ax7 but with lower noise. I have a whole list of Mil spec #s somewhere if you are interested.
Question.
What type of finish are you looking for? Black or Burgundy Tolex with white Piping is in Stock but other colors are possible.
I hope that covers your questions well. Please feel free to ask anything further if need be or if I missed anything. Shipping is done by Express post. About 1/2 the price of FedEx and still there with-in 4 or 5 days. Includes tracking and insurance. Also you should know I am about 4 weeks back ordered. Nice to be busy but it has it's drawbacks when everything is done by hand.
Thanks for your continued interest and have a Fab day.
Sincerely,
Rob Franklin
MY SECOND EMAIL IS BELOW
Hey Rob,
I wanted to touch base with you again, and let you know a few things.
One is, i just blew an ass load of money (ok, 1300) on recording equipment. you'd think this would make me shy of spending more, however just the opposite, it makes me realize my sore lack of a good (ok, great) recording amp -- i guess thats where YOU come in!
beyond that, i was hoping to sort of shore up an order, or at least get some preliminary feed back from you regarding how to proceed.
whatever you want to do to get the ball rolling on an amp order, I'm certain that your FabFox is the amp for me, so ...
that being said,
i know there are details regarding an option or two, and i'm not even at the stage to try and figure that out ... though i can tell you that my primary cabinet is a 2x12 that Earcandy Cabs made for me, and it is 8OHMS wired in STEREO (with i believe an emminence 35, and a 75, though it doesn't matter here)... so i was kind've hoping you could help me come up with a way that this amp i am ordering could be used to safely drive both that 2x12 8Ohm and also some sort of 1x12 -- i don't have one yet, and not knowing much about impedance, i was hoping you could give me input on if this was a problem, whether it could be solved by adding stereo outs to the amp, whether i just need some sort of external splitter, or what (and also what impedance the 1x12 would\should be to make this the easiest on you)
besides that, the other thing i'm focused on right now is the preamp and tube issue:
for the preamp, i guess i'm stuck in between on this.
i love the '59 plexi sound (in most respects, and it sounds like you've taken care of that with your mod)
but i do have a 100watt egnatter head that is specificaly made to reproduce an old plexi (which i think it does a great job on)
so, i'm kinda thinking the metalhead is indeed the preamp i should get.
let me tell you that my favorite guitar sounds are those heavy, thick, driven (we ain't talkin nu-metal though) sounds a'la Pearl Jam, Neil Young (think: the live album Weld), Jane's Addiction, and even stuff like Soundgarden, Sabbath, whatever ... i'm sure your on the track already ...
my primary OD unit as of now is a analogman modded TS909, and it works great with my egnater, but it still doesnt give me all that really cool feedback and aftersound that is so common with groups like The Who on stage (ok, obviously i realize that 2watts isn't gonna sound like The Who)
I guess i'm just asking you to sell me on the Metalhead so i don't feel bad about not picking up the '59 sound again!
OK. Now to the EL84 or 6V6 question ... i'm not sure i understand how my preamp option affects what tube i get, or if it does (is it really just a choice i get to make?)
Here is what my input would be ... i prefer the EL84 sound over the 6V6 for most applications, but i do like the headroom 6V6 gives for a clean sound (would i even have a clean sound with 6V6 if you gave me the metalhead preamp, though? more on that later) ...
so the only thing i would ask about the 6V6 is that THD sells the yellowjacket converter so you can plug EL84s in instead of a 6V6 ... that would almost make me want to get you to set up the circuit to accept 6V6, and then i could just plug in the yellow jacket and an EL84 and have the best of both worlds (still self biasing, right? plug and play?) ...
WHAT, in your opinion, IS THE DISADVANTAGE OF THAT?
is that a stupid idea? does the yellowjacket mess with the sound? is it even an option? would you recommend it? see where i'm going with this?
that whole 6V6 EL84 dillema (which is really about "clean" tone) made me think about the preamp as well ...
either way (splexi vs. metalhead) the tube is still 12AX7, correct?
in that case, i was browsing tubestore.com and noticed the following tube:
The GE JG-5751 is a NOS military version that has low microphonics and noise. It's our first choice for toning down high gain guitar amps. .
Special note for 5751 types: The 5751 is not a true 12AX7, but is often used in place of a 12AX7. They only have 70% of the gain of a 12AX7, and are often used to quiet down guitar amps that have too much gain. You can learn more about this on our tone tweak info page.
is this a possibility that i could use?
i'm just wondering. obviously i love gain
however, if i could do the whole 6V6\yellowjacket-EL84 thing ... i could keep a 6V6 and 5751 in there for a more fenderish\clean (ok maybe not fender, but cleaner, right?) sound, and then the yellowjacket\EL84 and a true 12ax7 for all out lead tones.
let me know what your take on this is, and whether a 5751 tube (which the site clearly specifies is not a "true" 12ax7) would even be acceptable in this amp.
Thank you so much for taking time to read this mess Rob.
I'm sure you will have questions to ask right back at me,
just let me know and try to steer me in the right direction with your questions.
if i'm forgetting stuff, point it out. if i'm way off the deep end, just say so.
ROBS FIRST RESPONSE TO MY FIRST EMAIL (mine isn't included, for brevity's sake)
Hi Nick,
Thanks for the kind words and interest.
I have great news about my Splexi and Metalhead preamps. They do not have the buzzsaw overly bright tone common to most original Marshalls. A common mod to those old amps is taking out the 470pf treble bypass cap, my stock amps have that already done. You should know that the Splexi is based on an early 1959 Plexi/JTM45, not a high gained amp, more room for powertube distortion. The Metalhead is similar to the Superlead100 offering a fair bit more preamp gain. Both amps can get the crunch but the Metalhead is more for 70s tone even though the name may imply a more modern voicing. Both amps take pedals real well.
The Voxylady is a whole different amp. It relies on the EF86 pentode for it's tone and only comes with a brill switch and gain knob, although the poweramp would still have master and top controls. It would be a very custom order on a Fox as the new faceplates are set up for full tone stack. However I could make a Chief(my other Vox based design) preamp using the new Fab tone stack. This would be much like the AC30 but with the improvements of the Matchless, Tophat and Fab designs added.
All Fab Fox's come stock with a power switch, so you have both 2 and 5 watts.
EL34 amps sound great but weight more. Also the trafos are much larger in an EL34 amp, so effecting the cost. SE EL34 produces about(depending on your PUs) 12watts or 5 when in low power mode. I have no Mullards but think I still have one Philips left.
EL84 is the standard for small British sounding amps. I have a few different NOS brands left. 2 watts is surprisingly loud through the right cab. A 1x12 is a good starting point. The Celestion Century seems to be the new fav speaker for low power, although I still like any Weber with Alnico.
My newly named Top knob(old name Mud) allows you to adjust the NFB which is IMO the main difference between Vox and Fender designs. Vox had an open loop design where as Fender used a large amount of NFB. This IMO made more tone difference than the type of OP tube allowing the Vox to be open and airy, the Fender a bit more thick and/or compressed with possibly lower noise. With the Fab Top knob you can explore both.
Attached is a pic of my latest monster amp in progress. A complete stereo VOX with SE KT88 output on one channel and 2xEL84 on the other. Not small like a Fox though. The Fox is designed for those smaller spaces that have become so popular as of late...
All for now, hope that helps and have a Fab day.
Sincerely,
Rob Franklin.
I was maybe looking for input from anyone ... maybe regarding a EL84 vs 6V6 tube specificaly, or if you want to chime in on what you think i should do for tolex and a cloth color, thats cool too. Or if you just want to tell me to fuck off, I'm ok with that as well.
Here is a set of emails, going in reverse chronilogical order (ie. the first email is Robs last response):
Nice to hear back from you. I'll try point form for your questions->
How to proceed/Order confirmation.
Orders are confirmed by payment.
Payment methods are,
Money Wire, direct from your bank account to my business account.
International Money Order like those sold by the USPS
or a Cashiers Check
I prefer bank wire, no waiting for the mail. For the MO or CC, Priority Mail seems to work OK.
Speaker Selection
I can make the amp with two speaker outs and a 4/8 ohm switch. When you use one cab have the switch on 8. When you use two just switch to 4ohms. Will be no prob if your speakers are all 8 ohm.
Preamp
The Splexi has nice Vintage tone. The Metalhead is right over the wall though. Definitely more gain than a SLP. It is so versatile with the new Sweep knob, everything form thick creamy smooth distortion to tight articulate individual note definition, all within one knob when the gain is up.The tone stack is pretty amazing. Marshall TMK invented the Sweep knob but only used it on one older design. Krank(LOL) picked it up but not too many others, great knob. Amazing enough the amp can still get blues like cleans, sorta Fenderish when the gain is down. It really cleans up well with the guitar volume, something a lot of folks like. Takes pedals well too so it is also good for 80s tones. I am a 70s guy though and this amp easily dials in Sabbath but also ZZTop, Zepplin, Niel Young, early EVH...with the right pedal it does Boston to Beck. Very playable, every time I build one I have a great time testing it for sure. It does get that controlled feedback and when driven can really be full of harmonics. It's not the power so much as the gain for what you are after. You also could switch up to 5 watts, 2 watts is the low power setting. Simply a great preamp. Less buzz than the Marshall and a bit more gain. Honestly a few clients of mine do not use OD pedals after they found the gain and tone inside the Metalhead. Nuff said, IMO the Metalhead is an ear opener so I would highly suggest that for you.
EL84/6V6
The EL84 is the standard for a small British style amp. That said thought the 6V6 is a sturdier tube. With true Class A, especially in triode mode(low power), the differences I have found to be slight at best. Lately a few companies have been focusing on 6V6 designs. I think they get a bad rap and are very capable of great tone in the right design. Unless you are in love with EL84 try the 6V6, you will be surprised to find most of the tone originates in the preamp design. Its how hard the preamp hits the poweramp that creates the best tones for rock. With a Metalhead in front you will not have to worry about tone...
Don't know how high the yellow jacket is but yes plug and play. If it fits well it should work for the EL84 but I don't think you'll need to play around with a Metalhead Fox. All the tone you need is built in, just plug and play. Years of me playing around with Marshall designs has already been implemented.
The 5751
IMO the tube will lower the gain BUT will not add headroom. The same effect would come from lowering the Gain knob if it is in the front end of the amp or lowering the Master if it is in the PI/driver stage. I guess that would be OK in an amp that did not have one of those knobs. That said any 5751 is a super quality tube, MIL spec originally and will work in any 12ax7 stage. I don't know about the re-issues but the tone and noise of NOS brands was great. Another tube is the 7025, same gain as the ax7 but with lower noise. I have a whole list of Mil spec #s somewhere if you are interested.
Question.
What type of finish are you looking for? Black or Burgundy Tolex with white Piping is in Stock but other colors are possible.
I hope that covers your questions well. Please feel free to ask anything further if need be or if I missed anything. Shipping is done by Express post. About 1/2 the price of FedEx and still there with-in 4 or 5 days. Includes tracking and insurance. Also you should know I am about 4 weeks back ordered. Nice to be busy but it has it's drawbacks when everything is done by hand.
Thanks for your continued interest and have a Fab day.
Sincerely,
Rob Franklin
MY SECOND EMAIL IS BELOW
Hey Rob,
I wanted to touch base with you again, and let you know a few things.
One is, i just blew an ass load of money (ok, 1300) on recording equipment. you'd think this would make me shy of spending more, however just the opposite, it makes me realize my sore lack of a good (ok, great) recording amp -- i guess thats where YOU come in!
beyond that, i was hoping to sort of shore up an order, or at least get some preliminary feed back from you regarding how to proceed.
whatever you want to do to get the ball rolling on an amp order, I'm certain that your FabFox is the amp for me, so ...
that being said,
i know there are details regarding an option or two, and i'm not even at the stage to try and figure that out ... though i can tell you that my primary cabinet is a 2x12 that Earcandy Cabs made for me, and it is 8OHMS wired in STEREO (with i believe an emminence 35, and a 75, though it doesn't matter here)... so i was kind've hoping you could help me come up with a way that this amp i am ordering could be used to safely drive both that 2x12 8Ohm and also some sort of 1x12 -- i don't have one yet, and not knowing much about impedance, i was hoping you could give me input on if this was a problem, whether it could be solved by adding stereo outs to the amp, whether i just need some sort of external splitter, or what (and also what impedance the 1x12 would\should be to make this the easiest on you)
besides that, the other thing i'm focused on right now is the preamp and tube issue:
for the preamp, i guess i'm stuck in between on this.
i love the '59 plexi sound (in most respects, and it sounds like you've taken care of that with your mod)
but i do have a 100watt egnatter head that is specificaly made to reproduce an old plexi (which i think it does a great job on)
so, i'm kinda thinking the metalhead is indeed the preamp i should get.
let me tell you that my favorite guitar sounds are those heavy, thick, driven (we ain't talkin nu-metal though) sounds a'la Pearl Jam, Neil Young (think: the live album Weld), Jane's Addiction, and even stuff like Soundgarden, Sabbath, whatever ... i'm sure your on the track already ...
my primary OD unit as of now is a analogman modded TS909, and it works great with my egnater, but it still doesnt give me all that really cool feedback and aftersound that is so common with groups like The Who on stage (ok, obviously i realize that 2watts isn't gonna sound like The Who)
I guess i'm just asking you to sell me on the Metalhead so i don't feel bad about not picking up the '59 sound again!
OK. Now to the EL84 or 6V6 question ... i'm not sure i understand how my preamp option affects what tube i get, or if it does (is it really just a choice i get to make?)
Here is what my input would be ... i prefer the EL84 sound over the 6V6 for most applications, but i do like the headroom 6V6 gives for a clean sound (would i even have a clean sound with 6V6 if you gave me the metalhead preamp, though? more on that later) ...
so the only thing i would ask about the 6V6 is that THD sells the yellowjacket converter so you can plug EL84s in instead of a 6V6 ... that would almost make me want to get you to set up the circuit to accept 6V6, and then i could just plug in the yellow jacket and an EL84 and have the best of both worlds (still self biasing, right? plug and play?) ...
WHAT, in your opinion, IS THE DISADVANTAGE OF THAT?
is that a stupid idea? does the yellowjacket mess with the sound? is it even an option? would you recommend it? see where i'm going with this?
that whole 6V6 EL84 dillema (which is really about "clean" tone) made me think about the preamp as well ...
either way (splexi vs. metalhead) the tube is still 12AX7, correct?
in that case, i was browsing tubestore.com and noticed the following tube:
The GE JG-5751 is a NOS military version that has low microphonics and noise. It's our first choice for toning down high gain guitar amps. .
Special note for 5751 types: The 5751 is not a true 12AX7, but is often used in place of a 12AX7. They only have 70% of the gain of a 12AX7, and are often used to quiet down guitar amps that have too much gain. You can learn more about this on our tone tweak info page.
is this a possibility that i could use?
i'm just wondering. obviously i love gain
however, if i could do the whole 6V6\yellowjacket-EL84 thing ... i could keep a 6V6 and 5751 in there for a more fenderish\clean (ok maybe not fender, but cleaner, right?) sound, and then the yellowjacket\EL84 and a true 12ax7 for all out lead tones.
let me know what your take on this is, and whether a 5751 tube (which the site clearly specifies is not a "true" 12ax7) would even be acceptable in this amp.
Thank you so much for taking time to read this mess Rob.
I'm sure you will have questions to ask right back at me,
just let me know and try to steer me in the right direction with your questions.
if i'm forgetting stuff, point it out. if i'm way off the deep end, just say so.
ROBS FIRST RESPONSE TO MY FIRST EMAIL (mine isn't included, for brevity's sake)
Hi Nick,
Thanks for the kind words and interest.
I have great news about my Splexi and Metalhead preamps. They do not have the buzzsaw overly bright tone common to most original Marshalls. A common mod to those old amps is taking out the 470pf treble bypass cap, my stock amps have that already done. You should know that the Splexi is based on an early 1959 Plexi/JTM45, not a high gained amp, more room for powertube distortion. The Metalhead is similar to the Superlead100 offering a fair bit more preamp gain. Both amps can get the crunch but the Metalhead is more for 70s tone even though the name may imply a more modern voicing. Both amps take pedals real well.
The Voxylady is a whole different amp. It relies on the EF86 pentode for it's tone and only comes with a brill switch and gain knob, although the poweramp would still have master and top controls. It would be a very custom order on a Fox as the new faceplates are set up for full tone stack. However I could make a Chief(my other Vox based design) preamp using the new Fab tone stack. This would be much like the AC30 but with the improvements of the Matchless, Tophat and Fab designs added.
All Fab Fox's come stock with a power switch, so you have both 2 and 5 watts.
EL34 amps sound great but weight more. Also the trafos are much larger in an EL34 amp, so effecting the cost. SE EL34 produces about(depending on your PUs) 12watts or 5 when in low power mode. I have no Mullards but think I still have one Philips left.
EL84 is the standard for small British sounding amps. I have a few different NOS brands left. 2 watts is surprisingly loud through the right cab. A 1x12 is a good starting point. The Celestion Century seems to be the new fav speaker for low power, although I still like any Weber with Alnico.
My newly named Top knob(old name Mud) allows you to adjust the NFB which is IMO the main difference between Vox and Fender designs. Vox had an open loop design where as Fender used a large amount of NFB. This IMO made more tone difference than the type of OP tube allowing the Vox to be open and airy, the Fender a bit more thick and/or compressed with possibly lower noise. With the Fab Top knob you can explore both.
Attached is a pic of my latest monster amp in progress. A complete stereo VOX with SE KT88 output on one channel and 2xEL84 on the other. Not small like a Fox though. The Fox is designed for those smaller spaces that have become so popular as of late...
All for now, hope that helps and have a Fab day.
Sincerely,
Rob Franklin.
If I was to smile and I held out my hand
If I opened it now would you not understand?
If I opened it now would you not understand?
Post edited by Unknown User on
0
Comments
i'm sure if i was picking and choosing and could use my ears, i'd end up with a fender blackface deluxe every time.
you know what sounds you are looking for and it seems like he's got a handle on how to give it to you. the very term "metalhead" scares me but that's just me.
i have 6V6 and EL84 amps. i don't really get to dip into saturating the EL84s though.
seems to me the EL84 would be a better match for the preamp in your case but i just don't know. my fender's got 6V6s and the fender is my main amp.
it seems to me that the EL84 would be a better match for the preamp but if he's recommending the 6V6, i wouldn't discount that.
and go with the burgundy and try to get a wheat fabric covering for the front if possible. that would look swell.
or match your cab.
The 5751 thing is great if you are needing a higher gain sound at lower volume levels, I just don't think this is the option to get on a small amp anyway, I want a stout preamp and an early breaking up power amp stange. The Tung Sol and EH combo in my orange has brought out the clarity a bit. Tesla JJ makes a hi gain 12AX7 that might be a good one to use.
If anything you want a hi gain (not distortion, gain before clip) preamp tube to save a little bit of clean headroom unless you simply want a purely crunchy OD sound with that amp.
You want a speaker that is very very efficient in the upper 90 dbs 98 or 99 if possible to make the most out of low power. I agree with him any weber alnico is grande, and the burgandy and wheat would be classy.
I really like the voxylady concept with the matchless inspired stuff. Anything for more harmonics and overtones. The EGDM would be a great match.
As for cosmetics, I'm partial to fawn. You don't see a lot of fawn these days...a very retro color.
good luck. Having some measure of design input always makes me feel closer to my instruments and amps. I hope that you experience that same sense of ownership in your tone and your fate as a musician.
old music: http://www.myspace.com/slowloader
just wanted to share this with you guys since we were shopping Junior's at one point and this was an unfortunate event.
damn man.
WHAT THE FUCK !?!
that's rough.
that's really really rough.
:(
If I opened it now would you not understand?
instead, he wants to rig me up a test version of a SWITCHABLE POWER TUBE AMP ... WTF ???
should i go for this?
My biggest concern, besides the complete failure of the amp, obviously ... is that of his mention of noise issues ... read on ... WOW ...
The amp does have 2 speaker outs. They are not stereo but dual mono.
The line out is designed to drive a mixer or poweramp. The slave out is designed to drive another guitar amp. Both have low level signals, not enough to drive a speaker. The best thing about either is you can use the extra send to add a mix of FXs without changing the original tone on the Fox. You can even use the Fox without a speaker, like a preamp with power tube tone. I build a protection device into the amp to make this possible, please don't try it with any other amp.
As for color as long as you decide before I start the build that is cool, in case I have to order your final choices.
I make a taller cabinet designed for a EL34 that should allow the use of a shorter YJ... BUT how about I build you my first amp with 2 OP sockets, one for EL84 and one for 6V6! It maybe a better way because the voltage drop designed into a YJ for the high voltage is not needed. The Fox being designed for true class A already runs at lower B+. The 6V6 and EL84 both require a lower B+ especially when in SE Class A and are very much a like. The heater current is different but that is something that a YJ does not compensate for either, but I could! Also the extra socket may cost less than ordering a YJ if you had to pay shipping...
I have fought the urge to do this before but as long as you promise never to try both tubes at once and don't mind keeping the rest of the amp pretty much stock we could create something new...
If this works like I think it should I will drop the 6L6 from the Fox line-up and make them all with switchable OPTs like above. My only concern in the past for this concept was around noise with all the extra wires needed... However the poweramp stage does not pick up noise easy and my ability, I must say as humble as possible, has improved over the years. If it does not work well I would simply convert it back to single socket and give you 2 American made preamp tubes in exchange for the stock Russian ones to make up for the 30 extra I need for the extra socket/custom work.
The cost BTW of upgrading your preamp tubes is 20 each. I have real vintage tubes. Preamp tubes bought as bulk PCBs from the RCAF when they decommissioned the Starfighter, others from 50/60s HiFi sets, some used...all tested electronically and by ear. I may have a GE 6V6 and a Sylvania EL84 if you would like an upgrade there, say 50 for both after stock tube exchange. All tubes warrantied 90days. American, British and even Canadian tubes just rock for tone and reliability. I'm sold out of German made tubes. They were petty much gold.
Thanks for your continued interest. I hope you don't mind me throwing out some more options that I think you may like. The old stock tubes will all be gone someday, not a day I look forward to but I have my private stock : )
If I opened it now would you not understand?
what is the preamp EF86? or 12AX7. My guess is the AMerican preamp tubes are the mullard copy 12AX7's Groove Tubes, I like them quite a bit in the fenders I've tried.
ask him if EF86 is a preamp option. Just for S and G. Dr. Z uses some EF86's in various designs that sound great, you can learn a bit more about that design at his site.
i believe it's a singular 12ax7 ...
(i know it's a 12ax7, but i'm pretty sure it's just 1. 1 preamp and 1 OP)
i can ask about the ef86, though i'm not sure he uses them in any of his amp designs, and therefore am not sure he is familiar with the design process for these tubes.
but i'll ask.
If I opened it now would you not understand?