Please help in improving the sound of a gain channel.

[nickb]

Hi, I want to get an opinion. At this point, I improved the amp to the point that I like the sound at low volume. But when I cranked it up, it seemed to have less distortion and sounded harsh. I was even looking at the CF stage in the other thread. My question is whether it's my ears the room or it's real?

the reason I ask is because if you look at the schematic, this it typical high gain design. The master volume is after everything. This means all the harmonics, sound characteristics remains the same regardless of the master volume setting. I verified the power amp was not clipping as the volume is about half only. I matched the preamp/power amp so it only clip the power amp at the very last bit. So the sound should be totally from the preamp.

So why the sound change? Do other amps have the same thing?

Fletcher-Munson curves maybe? Fletcher?Munson curves - Wikipedia, the free encyclopedia

[Alan0354]

That very well explains it. The perceived mid frequency rise as sound pressure rise, that must be the harshness I feel. But how do you design, according to the louder level of the amp?

But why is it sound more distorted at low volume?

BTW, I actually experimented, When I cranked up to the level that was harsh sounding, I used the attenuator to lower the volume, the sound returned to the softer fuzzier sound again.

[teemuk]

...how do you design, according to the louder level of the amp?

Simple. You tweak the circuit while listening the amp at the high volume levels you intent to use it at. Furthermore, you might want to listen to it in a band / musical context. Amp that sounds great alone usually doesn't sound all that great in the mix and vice versa.

This isn't any different from the usual stumbling block of inexperienced tweakers of modeling amps: patches tweaked to sound great when you play guitar alone at low volumes in bedroom sound entirely different - and usually awful - when you use them in a bandmix context at much higher volume levels and in an entirely different acoustic space. You need to tweak the thing to sound right in its intented application.

While at it: Have breaks. Brain processes sound in a way that you quickly get accustomed to all the "harshness" and unwanted characteristics in it. When you listen to a LOUD source it probably does this even faster.


Alternatively, you can try to design in a master volume control that compensates the Fletcher-Munson effect. ...Or just use the tone controls of the amp, thats what they are for anyway. An effect harder to compensate is that loudspeakers are unlinear devices too: the performance at low volumes and linear ranges of cone excursion is different than at higher volumes where excursion is limited and other effects, like thermal compression, start to kick in as well. Needless to say, scoping the amp's output will not display these effects.

[Chuck H]

We need a double like button!

I will say this about that though... As you're experience matures your brain sort of trains to hear good in the mix sounds and perceives them as good above the typical bedroom wanker tone. This is MHE anyway. And I think daz has some of this from years of band experience. He's been playing quiet for a while now though so maybe it's time for a tune up

Call up the boys daz and get that thang up loud!!! It's a good excuse to have some fun.

[J M Fahey]

What Teemu said.
Final tweaking must be made onstage.
And there is a definite "tired ear" syndrome.
I have been in countless recordings when everything starts to sound the same and you can't pick the best version .... or all mixes sound muddy .... or you pick the worst.

Usual action by an experienced Sound Engineer or Producer is to turn everything off, stop there, and send everybody home for a good night's sleep.

Next day you are reset and ready to go on.

[Chuck H]

Short story...

I was helping Dean Markley voice an amp he was considering for sale. We'd listen, make a change, listen, etc. When we thought we had something Dean called up the guitar player he plays in a band with and another friend, Ronnie Montrose! So The guys come over the next morning. Ronnie was driving an old Dodge van and wearing jeans and a T-shirt with some visible grass stains. I'll guess he lived nearby and was doing yard work. So we all proceed to take turns blasting away at real playing volume with me making the occasional tweak. After an hour and a half every one of us, including Ronnie whom I guess we thought would be somehow immune, agreed that it was all sounding the same and it was time to stop. So we shut down and one of us went out to get McDonalds. Me hangin' with Ronnie Montrose like a regular "Joe". Cool.

[Alan0354]

Problem is I don't play in the band. My music life have been over almost 40 years and electronics is my passion and hobby. I have not interest to get back into music.

[jazbo8]

I'll guess he lived nearby and was doing yard work.

Way cool, dude! Ronnie Montrose doing yard work, who woulda thunk! He was one of my favorites in high school, still have the album somewhere, got to dig it out and give it a listen.

[Chuck H]

I got to talk with him about how they got the tones for "Montrose"!!! Rock Candy specifically. Not the sort of thing anyone was trying to keep secret, but obscure info and a great tone.

[teemuk]

Problem is I don't play in the band. My music life have been over almost 40 years and electronics is my passion and hobby. I have not interest to get back into music.

Is it really a problem? If you are building the amp for yourself then build it for yourself, shouldn't be a problem in that. If you want to ensure it works in musical context / on stages etc. then maybe you can hook up with some guitarist still involved in the band scene and have him "demo" prototypes and advice what things should be changed. Or something like that.

[Chuck H]

+1
I don't play out anymore and I haven't put together any players to "play band" with since relocating from another state. So I go to customers gigs and listen to their recordings to see how the amps I build hold up in real world conditions. It's THE most important criteria for me and I have no personal way to test for it anymore. If I didn't have customers nearby that played out I would find another way. Super important.

[deci belle]

Alan, when you feel better and return to the forum, could you please post a schematic of your circuit upstream of the preamp?

I want to see what the output of the PT, rectifier and the power node voltages feeding the screens and PI are and what power tubes you designed this circuit for; EL34 or KT66?

I would like to investigate your project circuit now since you were able to run it past the pros!!