I am currently in the process of changing the power tubes and pre-amp tubes on my amp and would like to know 1) what type/brand of tube I can put in that will give me a more death metal sound and 2) are there any other simple modifications I can do to the amp to make it have that low crunch sound? To be more specific, at lower volumes the amp sounds pretty good (still not the sound that I would like though) when I crank it up it loses its clarity, noticeably.
I am currently running 2 Mesa Boogie 6L6's and the stock 12AX7's and 12AU7.
Any suggestions would be appreciated, even if they are for more than just simple mods. Also, I have never moded an amp so if it is somewhat complicated please explain.
I am currently running 2 Mesa Boogie 6L6's and the stock 12AX7's and 12AU7.
Any suggestions would be appreciated, even if they are for more than just simple mods. Also, I have never moded an amp so if it is somewhat complicated please explain.
Not to pee on your campfire or anything, but I think that the point of the tubes is to get away from that type of sound. You need some solid state diode or opamp type distortion and some EQ, most likely. Have you tried any pedals?
Another problem might be the speakers. If you're looking for more bottom end, a different speaker might be the ticket.
Another problem might be the speakers. If you're looking for more bottom end, a different speaker might be the ticket.
I don't play guitar. And tubelab knows infinitely more about these things than I. But I do know people who play hardcore/metal and they all, as far as I know, use tube gear.
From one of tubelab's post it seems there's no easy answer. I just talked to a friend, who asked me if I had any Mullard EL34s. He has tried every other brand and they don't sound like the Mullards. But based on tubelab's post, it doesn't mean Mullard is the solution for your amp.
The main purpose of this post is to say, you're in the right using tubes. SS might work just as well. But it's not more suited for the sweet sound of grinding death metal guitars.
From one of tubelab's post it seems there's no easy answer. I just talked to a friend, who asked me if I had any Mullard EL34s. He has tried every other brand and they don't sound like the Mullards. But based on tubelab's post, it doesn't mean Mullard is the solution for your amp.
The main purpose of this post is to say, you're in the right using tubes. SS might work just as well. But it's not more suited for the sweet sound of grinding death metal guitars.
WTF is with these bizarre replies? The guy asked a simple question.
I would recommend considering a tube swap 1st. Here's some reviews on 6L6 types: http://www.thetubestore.com/6l6review.html
and 12AX7 types:
http://thetubestore.com/12ax7review.html
and see if anything there piques your interest.
You can even try something as drastic as a 12AX7 swap for that 12AU7, but I would post a schematic here for people to look over to make sure it's safe.
I would recommend considering a tube swap 1st. Here's some reviews on 6L6 types: http://www.thetubestore.com/6l6review.html
and 12AX7 types:
http://thetubestore.com/12ax7review.html
and see if anything there piques your interest.
You can even try something as drastic as a 12AX7 swap for that 12AU7, but I would post a schematic here for people to look over to make sure it's safe.
I replaced the kathode resistors in the preamp in my amp with red Led`s, got harder distortion. (also removed the bypass caps).
I also installed LED`s back-to-back, as clipping diodes, worked great!
Not sure if it will work well in your amp...
I also installed LED`s back-to-back, as clipping diodes, worked great!
Not sure if it will work well in your amp...
It is hard to say what would sound good in your particular amp. I have never tinkered with any Crate amps. I tend to just try a bunch of different tubes to see what happens, but I have a lot of tubes to try.
Mullard EL34's just cost too much for me to ever use in a guitar amp, but I tend to use cheap tubes in my amps. I don't play in live situations where a blown tube would be a problem either.
There is no easy answer, but if you have access to some tubes to try, swap away. There are several different brands of 6L6 type tubes available, and I don't know of any particular brands to avoid, but I have not been as involved with guitar amps as much as I used to, due to the lack of time. I haven't built a complete guitar amp in about 5 years. (I am way overdue)
As stated before, the speakers make the biggest change in sound, then the transformers, then the tubes, and then the other parts. Obviously the easiest path to take it tube swapping. There are lots of modifications that can be made to change the sound of an amp, but most of them are pretty amp specific.
About 10 or 12 years ago, a guy came to me with a book full of amp mods, and an old Fender amp, and asked me to do some of the mods to his amp. One thing led to another, and I wound up building him a new amp. I haven't seen him in many years, but I got one of those books. Most of the mods are old Fender specific, but the explanations are good for all, and the book is full of schematics (remember this was the beginning of the internet era, schematics were hard to find). I have built amps from those schematics. The book is still available at Sam Ash music and Amazon. It is called "A desktop reference of hip vintage guitar amps" by Gerald Weber. ISBN# 0-9641060-0-0
I routinely try just about any tube that has the right pinout in the preamp positions. 12AX7, 12AU7, 12AT7, 12BH7, 12DW7, 5751, 5814, 6201, 5963, 5965, etc. I have never had any thing bad happen, but it is remotely possible, especially if there is a DC coupled driver stage. Puting a 12AX7 where a 12AU7 belongs usually doesn't work because the bias is all wrong, but it does give an overdriven distortion if it does work. Try a 12AT7 instead, I have had better luck with it. If you are using a distortion pedal, try going the other way, put a 12AU7 (or 12AT7) in place of the first 12AX7.
Most of my tube experiments have been on Fender or Marshalls, or their clones. I couldn't find a schematic of this amp on the web for download, so I can't tell you if these experiments are safe for your particular amp.
Mullard EL34's just cost too much for me to ever use in a guitar amp, but I tend to use cheap tubes in my amps. I don't play in live situations where a blown tube would be a problem either.
There is no easy answer, but if you have access to some tubes to try, swap away. There are several different brands of 6L6 type tubes available, and I don't know of any particular brands to avoid, but I have not been as involved with guitar amps as much as I used to, due to the lack of time. I haven't built a complete guitar amp in about 5 years. (I am way overdue)
As stated before, the speakers make the biggest change in sound, then the transformers, then the tubes, and then the other parts. Obviously the easiest path to take it tube swapping. There are lots of modifications that can be made to change the sound of an amp, but most of them are pretty amp specific.
About 10 or 12 years ago, a guy came to me with a book full of amp mods, and an old Fender amp, and asked me to do some of the mods to his amp. One thing led to another, and I wound up building him a new amp. I haven't seen him in many years, but I got one of those books. Most of the mods are old Fender specific, but the explanations are good for all, and the book is full of schematics (remember this was the beginning of the internet era, schematics were hard to find). I have built amps from those schematics. The book is still available at Sam Ash music and Amazon. It is called "A desktop reference of hip vintage guitar amps" by Gerald Weber. ISBN# 0-9641060-0-0
I routinely try just about any tube that has the right pinout in the preamp positions. 12AX7, 12AU7, 12AT7, 12BH7, 12DW7, 5751, 5814, 6201, 5963, 5965, etc. I have never had any thing bad happen, but it is remotely possible, especially if there is a DC coupled driver stage. Puting a 12AX7 where a 12AU7 belongs usually doesn't work because the bias is all wrong, but it does give an overdriven distortion if it does work. Try a 12AT7 instead, I have had better luck with it. If you are using a distortion pedal, try going the other way, put a 12AU7 (or 12AT7) in place of the first 12AX7.
Most of my tube experiments have been on Fender or Marshalls, or their clones. I couldn't find a schematic of this amp on the web for download, so I can't tell you if these experiments are safe for your particular amp.
leadbelly, thanks for the info, I was actually just on that page today though. So I guess a related question to what you have posted is what changes the sound of an amp more the pre-amp tubes or the power tubes? From what I have read, I think I remember that the pre-amp tubes will have a much greater impact. If you have a different opinion please let me know.
Peter, I sort of don't know what your trying to say. I should have also said that I am not familiar with amp circuitry, even though I am sure that I could learn pretty quickly. If you don't mind, please explain in a bit more detail and also state what each mod that you did does. Thanks!
Why would you not be able to get a death or black metal sound from tubes, especially 6L6's? Is the 6L6 not the common tube used for a metal sound?
On that note, should I consider possible changing the tubes to 6551's?
Lastly, I guess that I should have mentioned that my 6212 is from the Blue Voodoo line. I was not aware that Crate had manufactured a non-Blue Voodoo 6212.
The schematics for this amp are at http://www.americanmusical.com/Manuals/Crate/BV6212Combo_manual.pdf
Peter, I sort of don't know what your trying to say. I should have also said that I am not familiar with amp circuitry, even though I am sure that I could learn pretty quickly. If you don't mind, please explain in a bit more detail and also state what each mod that you did does. Thanks!
Why would you not be able to get a death or black metal sound from tubes, especially 6L6's? Is the 6L6 not the common tube used for a metal sound?
On that note, should I consider possible changing the tubes to 6551's?
Lastly, I guess that I should have mentioned that my 6212 is from the Blue Voodoo line. I was not aware that Crate had manufactured a non-Blue Voodoo 6212.
The schematics for this amp are at http://www.americanmusical.com/Manuals/Crate/BV6212Combo_manual.pdf
IxKaCKxI said:
There's no schematic in that .pdf, just a block diagram.
Hard to say "do this and you will be happy". Sure, switching preamp tubes from one type to another will achieve a more dramatic change, but will it lead to clearing up the muddy sound you hear when playing loud is hard to say. I would take tubelab's advice, buy a 12AT7 and try it both swapping out the 12AX7 and the 12AU7 and see if you like it. It's just the price of 1 tube after all.
If you want crazy crunch and/or distortion, sub out one of your 6L6's with an EL84 or KT88 or other random octal power tube. The incompatibility and inequal plate load will register as wicked distortion. Unless your OPT a splodes.
Schematics
Tubelab, thanks for the info. However, I do not have any spare tubes nor do I know anybody that does. So that type of experimentation is out of the question for now.
But if you please could, can you tell me what changing the pre-amp tubes in a specific location does (not necessarily particular to this amp.)
Also, I believe that the link that I posted is not of the schematics that were asked for. What I posted is just some basic stuff. I will try to find them somehow.
Tubelab, thanks for the info. However, I do not have any spare tubes nor do I know anybody that does. So that type of experimentation is out of the question for now.
But if you please could, can you tell me what changing the pre-amp tubes in a specific location does (not necessarily particular to this amp.)
Also, I believe that the link that I posted is not of the schematics that were asked for. What I posted is just some basic stuff. I will try to find them somehow.
is it a VC-6212 or a BV-6212 Blue Voodoo? If it IS a blue voodoo, then it is a Mesa Boogie Recto/Soldano clone as all Blue Voodoos are.
i am going to work under the assumption that it is... if it is not then disregard most of this. i have worked on many variants of that circuit, soooo you can go far by converting the output stage to adjustable bias and dropping a pair of JJ 6l6's in there, and cranking them up to 70% dissapation. The Voodoo output stage uses adjustable bias that is not ...er... adjustable, kinda like the older peavey 5150's and Mesa Dual rectifiers. You can convert the fixed bias range resistor with a trimmer pot and bias it up properly. That gets rid of the crossover distortion hash and thickens up the sound nicely.
Better 12ax7's will help out too. They ship with Sovtek 12ax7a IIRC. in that circuit, try a JJ ecc83s in the first position and Sovtak 12ax7LPS in the other slots. Get one with matched sections for the last slot... that is the phase inverter.
As far as modifications to the circuit... a good place to start is to replace all the cost-cut parts with better ones for less fizzy tone and lower noise. Replace the elecrolytic cathode bypass capacitors (should be little blue 1uF caps) with film capacitors, then replace all the input stage and FX loop recovery stage resistors with good metal film resistors... 1 watt if you can find them. Then do all the 100k plate resistors in the preamp with nice metal films, again 1 watt preferably--the tiny carbon resistors they use there are pretty noisy, and plate voltages are pretty high and most off the shelf 1/4-1/2 watt metal films can't take it.
The coupling capacitors in those are pretty crappy too IIRC. I'd replace them with better ones. i prefer mylar/polyester film + foil in those circuits 400v... polyprop is way too hard sounding... trust me... or try it and see, but I can almost guarentee you won't like it. Mallory 150's are pretty much the standard but are hard to mount on a PC board, so Sprague 225p's work too
if i had a schematic in front of me, i could be of more help if you are looking for a particular tone, but I don't have one at the moment. Most tone sculpting changes there would be in the grid stoppers, treble peaking circuits, and tone stack, but i can't recommend changes until I can see the circuit and know what you want. if you are looking for a more scooped sound, try replacing the .022u bass cap in the tone stack with a .1u, and the .022u mid cap with a .047u. it will shift the mid cut down a bit and bump up the lows.
Also, the cathode resistor on the very last preamp stage in the dirty channel has a lot to do with the distortion character... you could tweak that one... it should be 1.8k... try dropping it to 1k or 820r and see if you like it better.
Hope that helps...
i am going to work under the assumption that it is... if it is not then disregard most of this. i have worked on many variants of that circuit, soooo you can go far by converting the output stage to adjustable bias and dropping a pair of JJ 6l6's in there, and cranking them up to 70% dissapation. The Voodoo output stage uses adjustable bias that is not ...er... adjustable, kinda like the older peavey 5150's and Mesa Dual rectifiers. You can convert the fixed bias range resistor with a trimmer pot and bias it up properly. That gets rid of the crossover distortion hash and thickens up the sound nicely.
Better 12ax7's will help out too. They ship with Sovtek 12ax7a IIRC. in that circuit, try a JJ ecc83s in the first position and Sovtak 12ax7LPS in the other slots. Get one with matched sections for the last slot... that is the phase inverter.
As far as modifications to the circuit... a good place to start is to replace all the cost-cut parts with better ones for less fizzy tone and lower noise. Replace the elecrolytic cathode bypass capacitors (should be little blue 1uF caps) with film capacitors, then replace all the input stage and FX loop recovery stage resistors with good metal film resistors... 1 watt if you can find them. Then do all the 100k plate resistors in the preamp with nice metal films, again 1 watt preferably--the tiny carbon resistors they use there are pretty noisy, and plate voltages are pretty high and most off the shelf 1/4-1/2 watt metal films can't take it.
The coupling capacitors in those are pretty crappy too IIRC. I'd replace them with better ones. i prefer mylar/polyester film + foil in those circuits 400v... polyprop is way too hard sounding... trust me... or try it and see, but I can almost guarentee you won't like it. Mallory 150's are pretty much the standard but are hard to mount on a PC board, so Sprague 225p's work too
if i had a schematic in front of me, i could be of more help if you are looking for a particular tone, but I don't have one at the moment. Most tone sculpting changes there would be in the grid stoppers, treble peaking circuits, and tone stack, but i can't recommend changes until I can see the circuit and know what you want. if you are looking for a more scooped sound, try replacing the .022u bass cap in the tone stack with a .1u, and the .022u mid cap with a .047u. it will shift the mid cut down a bit and bump up the lows.
Also, the cathode resistor on the very last preamp stage in the dirty channel has a lot to do with the distortion character... you could tweak that one... it should be 1.8k... try dropping it to 1k or 820r and see if you like it better.
Hope that helps...
PS...
Replace the speakers. it is the 2x12" combo right? Get a pair of Celestion Vintage 30's, or Eminence Governors or Wizzards if you are looking for that big metal sound. not my favorite speakers, but i think they may be what you are looking for.
Replace the speakers. it is the 2x12" combo right? Get a pair of Celestion Vintage 30's, or Eminence Governors or Wizzards if you are looking for that big metal sound. not my favorite speakers, but i think they may be what you are looking for.
Swaping the preamp tubes changes the gain lineup of the entire preamp chain. Swapping the tubes with the same type from a different manufacturer makes small changes in gain and tonal character due to the differences in the way the individual manufacturers make the tubes. Swapping the tubes to a different type makes large changes in the gain and tonal character. Often the changes are large enough to cause distortion if high gain tubes are used, and sometimes the distortion sounds cool (not intended for HiFi use) and often it doesn't. Sometimes puting in a lower gain tube and driving it hard with an effects pedal will impart an entirely different sound to the amp. This is best done to one channel of a dual channel amp with the ability to swap channels in a live situation via footswitch.
It the preamp tube world the 12AU7 has the lowest gain, followed by the 12AT7 then the 12AX7.
Aletheian, that sounds like whole lot of work, but I'm sure very well worth it. Do you think that someone like myself, who has no previous experience doing this, can do this? How much will this end up costing, aside from the speakers?
And yes you are correct, this is the BS series, I was unaware that after this, or maybe even before, crate had made a VC series.
Tubelab, so does having a high gain tube mean that it will distort later or vice versa?
I have seen a few posts mentioning various books on tube amp modification. Which do you guys recommend? Besides that it there a specific resource (online or in print) that I can read to teach me the basics?
And yes you are correct, this is the BS series, I was unaware that after this, or maybe even before, crate had made a VC series.
Tubelab, so does having a high gain tube mean that it will distort later or vice versa?
I have seen a few posts mentioning various books on tube amp modification. Which do you guys recommend? Besides that it there a specific resource (online or in print) that I can read to teach me the basics?
If you have no previous experience, then I'd recommend doing the tubes and the speakers. The reason bein' is that there is a danger of damaging the traces on the PC board if you are not slick with a soldering/desldering iron. if you DO in fact have a Blue Voodoo with non-adjuatable output stage bias, shops usually charge about $50 for the mod to make it adjustable... which would be the next step.
That depends a lot on the circuit, and its operating conditions, but usually the answer is yes, for one of two reasons. Most of the higher gain tubes have a narrower range of operating conditions where they operate cleanly. Odds are, a high gain tube will not be in its sweet spot, so it will distort. This is not always a good sounding distortion, and in extreme cases the amp will not even make a sound. If the tube does wind up in (or near) its sweet spot, it will have a bunch more output, driving the following stages into clipping. This can lead to that super sustaining modulate the sound with the volume knob kind of sound. Unfortunately most amp manufacturers have already put 12AX7's in all of the preamp stages, which have the highest gain of all of the popular tubes.
aletheian said:
Yes I do have a Blue Voodoo, in one of the posts I made a typo and said BS amp, which obviously does not exist.
Anyways, does output biasing have anything to do with the hum balancer or are they completely different thigns. I apologize for my lack of knowledge in this area. Also, in a previous post you recommended JJ brand tubes. Why do you recommend those as opposed to another manufacturer? Would modding the amp to accept KT88's (like the BV heads) make a dramatic difference? As far as speakers go, you recommended some speakers that you are not so fond of. I listened to some of the songs from your band and I like the sound that you guys have, so maybe I did not communicate properly the type of sound that I would like. I do NOT want a sludgy death metal sound, I want it to be crisp (have crunch) but at the same time to hit the lows really well. So taking that into account, do you still recommend the same type of speakers.
Lastly, could you please give me a recommendation for a good book to learn about tube amps. It really sucks that I am not able to fully understand and appreciate the tips that you and tubelab are giving me.
Check out the theory documents inder the "P1" project at ax84.com. They are reprints of a great old series of articles that might shed some light on the subject... check out the forum as well while you are there... it is more guitar amp oriented.
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