Tight bass response question?

[Chuck H]

OK. That helps. At this point it should probably be mentioned that if tight bass is a priority el84 tubes are not the best choice in tube type. Not that they can't be made tight enough. I know they can. But it's sort of like wanting a fast car and asking how to soup up your VW Beetle. Sure it can be done.

El84 tubes are most popular in guitar amps because of their jangle, chime and "creamy" distortion character. Creamy and tight aren't usually adjectives for the same amp. But, el84 tubes do a pretty good Jekyll and Hyde thing. Under 350Vp they do their characteristic tone pretty well. But get them up between 390Vp and 400Vp in AB1 and they lose their characteristic tone but get loud and tight. It should be said that they don't last very long at higher voltages. Especially in combo type amps. If you crank the amp for power tube distortion and play five hours a week you'll need to change tubes every four or five months. Not too bad since they're not expensive tubes.

I'll second the main filter having more uf too.

As I was writing this I looked up the High Octane schematic... Now we're just getting silly because it's a little single ended el84 thing. That means no high Vp for you. It also means assymetrical clipping. If tight bass from a pair of el84's in AB1 is like souping up a VW Beetle then tight bass from a single ended el84 is like trying to soup up a golf cart.

I'll ask again, what kind of music do you play? It's an important question to determine what you might mean by "tight bass".

EDIT: You have another thread asking 'how to get distortion'. Your asking questions with very broad strokes without defining your goal well enough. We can't give you a recipe if you don't tell us what you want to eat. Amplifier types aren't as interchangeable as you may think. That is, not all amp designs can be tweaked to do what you want them to if you want something they're not already designed for. You wouldn't want to be the guy in a metal band playing a Telecaster through a tweed Deluxe. We need to know what you want your amp to do. So far what we know is that you want to know how to get distortion, you want tight bass and your looking to build a single ended el84 amp. You may be getting in your own way here. We can't draw a map if you don't tell us where your going. And you definitely seem to be lost now.

[Rod]

OK. That helps. At this point it should probably be mentioned that if tight bass is a priority el84 tubes are not the best choice in tube type. Not that they can't be made tight enough. I know they can. But it's sort of like wanting a fast car and asking how to soup up your VW Beetle. Sure it can be done.

El84 tubes are most popular in guitar amps because of their jangle, chime and "creamy" distortion character. Creamy and tight aren't usually adjectives for the same amp. But, el84 tubes do a pretty good Jekyll and Hyde thing. Under 350Vp they do their characteristic tone pretty well. But get them up between 390Vp and 400Vp in AB1 and they lose their characteristic tone but get loud and tight. It should be said that they don't last very long at higher voltages. Especially in combo type amps. If you crank the amp for power tube distortion and play five hours a week you'll need to change tubes every four or five months. Not too bad since they're not expensive tubes.

I'll second the main filter having more uf too.

As I was writing this I looked up the High Octane schematic... Now we're just getting silly because it's a little single ended el84 thing. That means no high Vp for you. It also means assymetrical clipping. If tight bass from a pair of el84's in AB1 is like souping up a VW Beetle then tight bass from a single ended el84 is like trying to soup up a golf cart.


I'll ask again, what kind of music do you play? It's an important question to determine what you might mean by "tight bass".

Hi Chuck!

Well thanks for you help and reply to my question, i'f i change the el84 tube to a 6l6gc, will this improve the results?
what do i have to change in the circuitry besides the Output transformer?

The "tight bass" means that palm muted chug, very commom for metal players.

[J M Fahey]

Go solid state.
And yes, you can add a damping control.

[hasserl]

An amplifier circuit is a complete design, it usually doesn't work very well to just substitute the power tube and output transformer and expect good results.

The AX84 project is a good way to get into the hobby of building guitar amps, It's a simple design that works well and many people have built it and enjoyed it. But it is what it is, and I don't think it makes a great amp for chugga-chugga drop D palm mute type playing. Think more of higher gain classic rock stuff. It's not a mini 5150 or Dual Rectifier, and you aren't going to turn it into one by changing the power tube to 6L6.

But like I said, it is a good way to get started building and to LEARN about building. I'd say if that is your goal, then do it. If you're not really wanting to learn about amp building but think this is a cheap way to get an amp, then don't do it, you'll be disappointed. The AX84 project also has a great community where a guy can get a lot of support. I've never been a member there, but I've lurked at times and sen they have some great discussions over there. I've often advised newbies looking for a way to get started to head over there.

To answer your question about good filtering on the AX84 Hi-Octane, C1 to C4 are the filter caps. they are in the power supply to smooth ripple and to provide a sort of "reservoir" for the power supply to the tubes. But being a class A design, meaning the tube draws full current at all times, even at idle, increasing the value of those caps may not give the expected result, since there is no sag in the power supply of class A amps. The filtering on that amp is already pretty goods to start with. Why don't you build it as it is designed to start with, learn all you can about amp design, then think about making circuit mods after that. I bet you'll rather start thinkjing about another build for your chugga-chugga amp at that point.

[big_teee]

well i'm thinking in build the AX84 Hi-Octane Tube Guitar Amplifier Project, after this i want to tweak some things to taste, and the tight bass response is one of them.

I looked around that site, and it seems way over priced for what you get.
They also seem to not want anyone to see any pictures of kits and components.
Or, I may have never got to the right area for that.
I would start with a small amp kit like a champ, or something, with a good layout.
Tweed Champ Vacuum Tube Amp Kit
Good Luck with whatever you decide!
Terry

[Chuck H]

I'd just like to say to the OP... You still haven't defined your goals or told us what kind of music you play. I think that a modern metal tone has been eluded to. With the info I have I would suggest...

Build a high gain preamp w/master volume type amp. Make it big enough so that you can turn it up at a practice or medium sized gigs without saturating the power amp. My reasoning?..

Big gothic distortion starts to get lost when you saturate the power amp (in general) and you end up with a more "classic" rock kind of midrange tone. If you want the amp to chug and reproduce a low B you need to keep the power amp within a range of headroom to do so. And since you need to do this anyway for bedroom, practice or gigs it only makes sense to build a master volume amp with enough power to handle those situations. Something like a half power SLO would probably be a good choice. It's a complicated built but has proven popular. So lots of info is available. When rolling your own amp the cost difference between a 3W single ended design and a fifty watter is pretty small. I just think your too green to make your own decision about what amp would be best for you because you chose the 'High Octane'. Considering your goals I would say again, don't get in your own way. If I had a bunch of money to invest I wouldn't start looking (on my own) for stuff to invest in. would find a financial consultant to guide me. Consider yourself guided. If you play metal almost nothing at the AX84 site is appropriate for you.

[Steve Conner]

Thanks Chuck. That is quite true, or at least it agrees with my experience of designing a metal amp. You generate the "chug" by cutting some bass before the preamp to "de-fart" the distortion, then scooping out midrange just before the power amp. The power amp has to run clean, or it'll fill in the midrange scoop with its own distortion harmonics, and you get a mushy, over-gained version of the classic rock tone.

My only worry is that a metal amp is a complex beast, not really a project for a complete beginner lacking test equipment. A Champ style kit would have a higher chance of actually working. And you can always use it as a distortion pedal in front of a graphic EQ and a Peavey CS800.

[Chuck H]

My only worry is that a metal amp is a complex beast, not really a project for a complete beginner lacking test equipment. A Champ style kit would have a higher chance of actually working. And you can always use it as a distortion pedal in front of a graphic EQ and a Peavey CS800.