Hi all,
After having read 4 or 5 of some good books and having now a pretty consistent understanding of overall amps technologies, I am wondering where/how I could learn which design to go for if I want to achieve such or such tone - some guidelines in fact. Books describe each stage with a very great accuracy but I still miss the holistic approach of amp design depending on different styles.
As an example, refering to my previous post about Samamp VAC 23 and this particular video https://www.youtube.com/watch?v=ay4iAiC3fsk or this one https://www.youtube.com/watch?v=J8Gb-fSUHlU, it is obvious that it has this dirty, mid boost, cranked sound with a kind or mysterious rotary effect that I don't explain (someone knows about this?). As I can't find any Samamp schematic for reference, I could I know:
- how many preamp valves I need?
- should I build a class A or AB?
- single-end or pushpull?
- cathode bias or fixed bias for power stage?
- cathode follower technology?
- 10'' vs 12'' vs15'' speaker?
- Tone stack choice?
...
I don't want to try by myself all the combinations of these different technologies - I don't have such time in my life. I only think about building my own modest amp which simply fits my needs.
Thanks guys!
Existing design choices guidlines?
Moderators: pompeiisneaks, Colossal
Re: Existing design choices guidlines?
Respectfully, I believe you are overthinking this. There are a few things to consider, some of which are intangible, one of which is raw chops and technique. I was trolling youtube the other day and saw Jerry Garcia sitting in with Los Lobos using David Hidalgo's Les Paul. Jerry wasn't using Wolf or Tiger, which you'd think might be a big deal. No, it still sounded just like Jerry. I've also seen a video of Eric Clapton sitting in with (I forget who) where they hand him some POS guitar and a worse amp to work with and he still sounds like Eric. There is a lot of tone and other nuance that is on the player's fingers and you obviously can't build that into the amp. The videos you point to -- that guy has lots of technique. It's a simple point; temper your expectations.
You've asked a number of questions about amp topology and circuitry. I don't think I'd start there. We are, for the most part, amp cloners. Those who advance, get tired of cloning and will branch out to mix and match or variations on a theme as a strategy. There are a few who actually know a great deal and are real-deal amp designers.
Class A vs AB is mostly an artifact of what you build. I'm doubtful a beginner can effectively control the result and I submit it isn't important. As for the rest, I suggest that it is far easier to choose a relatively simple design that has tonal qualities you like, and try to build it. Later, you can learn how to modify it to do other things (within reason) or you build another that's different.
You probably won't find that SAM amp schematic as it is likely protected intellectual property. It isn't the end of your hopes if you can't get it.
There are probably less than a half-dozen commonly used tone stacks. Choose the one you think you like.
Power amp sections are considerably more vanilla. If the amp you are looking at has more power than what you want, scale it back. Pick a tested design that uses lower power tubes. If that isn't low enough, build it with a master volume or power scaling. Remember that a 10W amp sounds half as loud as a 100W amp, and a 3W amp, while still loud, is only a little less loud than a 5W or 10W amp.
The speaker you choose will color the tone, as well.
There are lots of choices. I'd just go with the flow on topology. Use your ears and common sense to make a choice. (Youtube will let you audition just about anything with your ears.) I'm guessing you should look at the typical 3x 12AX7 preamp and low power (EL84 or 6V6) push pull power section. This will be a handful for a first build. Look for something that's well documented and comes with good layout drawings. Otherwise it is likely you will find yourself in over your head and frustrated. I don't think you want that.
Finally, book learning, while of good value, doesn't translate into manual skills nearly as easily as you'd think. There is a bit of art involved in getting am amp built.
Good luck.
You've asked a number of questions about amp topology and circuitry. I don't think I'd start there. We are, for the most part, amp cloners. Those who advance, get tired of cloning and will branch out to mix and match or variations on a theme as a strategy. There are a few who actually know a great deal and are real-deal amp designers.
Class A vs AB is mostly an artifact of what you build. I'm doubtful a beginner can effectively control the result and I submit it isn't important. As for the rest, I suggest that it is far easier to choose a relatively simple design that has tonal qualities you like, and try to build it. Later, you can learn how to modify it to do other things (within reason) or you build another that's different.
You probably won't find that SAM amp schematic as it is likely protected intellectual property. It isn't the end of your hopes if you can't get it.
There are probably less than a half-dozen commonly used tone stacks. Choose the one you think you like.
Power amp sections are considerably more vanilla. If the amp you are looking at has more power than what you want, scale it back. Pick a tested design that uses lower power tubes. If that isn't low enough, build it with a master volume or power scaling. Remember that a 10W amp sounds half as loud as a 100W amp, and a 3W amp, while still loud, is only a little less loud than a 5W or 10W amp.
The speaker you choose will color the tone, as well.
There are lots of choices. I'd just go with the flow on topology. Use your ears and common sense to make a choice. (Youtube will let you audition just about anything with your ears.) I'm guessing you should look at the typical 3x 12AX7 preamp and low power (EL84 or 6V6) push pull power section. This will be a handful for a first build. Look for something that's well documented and comes with good layout drawings. Otherwise it is likely you will find yourself in over your head and frustrated. I don't think you want that.
Finally, book learning, while of good value, doesn't translate into manual skills nearly as easily as you'd think. There is a bit of art involved in getting am amp built.
Good luck.
Re: Existing design choices guidlines?
Phil_S
Thanks for the time spent on answering! I got all your points and I highly agree with this. I play blues guitar since almost 20 years now, I obviously know what's the part of the player's technique in sound's shaping. On the practical side, I also know that every art takes time to learn and the best way to start is to clone what has been done previously and learn from this. According to what you say, I deduce that tone shaping (in all levels) is probably the most important point whichever the choosen design.
Though, a simple illustration of what I meant is that I recently bought a Hot Rod Deville 4*10. It is almost impossible to obtain the SRV dirty, compressed and granular sound with it. However it sounds fantastic with my Gretch hollow-body: very consistent sound with fantastic attack and great precision. I know then that I would rather choose a AC15 design for a dirty blues sound. Beeing built differently, it does mean that there is an underlying technology responsible for each sound signature. Considering fixed vs self output tube bias, one is said to bring punch, tighter bottom end and focus - the other one compression, overall sag and more singing sound. This is the knowledge I was talking about, if this makes sense to you.
Badoumba
Thanks for the time spent on answering! I got all your points and I highly agree with this. I play blues guitar since almost 20 years now, I obviously know what's the part of the player's technique in sound's shaping. On the practical side, I also know that every art takes time to learn and the best way to start is to clone what has been done previously and learn from this. According to what you say, I deduce that tone shaping (in all levels) is probably the most important point whichever the choosen design.
Though, a simple illustration of what I meant is that I recently bought a Hot Rod Deville 4*10. It is almost impossible to obtain the SRV dirty, compressed and granular sound with it. However it sounds fantastic with my Gretch hollow-body: very consistent sound with fantastic attack and great precision. I know then that I would rather choose a AC15 design for a dirty blues sound. Beeing built differently, it does mean that there is an underlying technology responsible for each sound signature. Considering fixed vs self output tube bias, one is said to bring punch, tighter bottom end and focus - the other one compression, overall sag and more singing sound. This is the knowledge I was talking about, if this makes sense to you.
Badoumba