Yet another Guitar amp project

[akis]

Originally Posted by MJL21193

Thanks,
I will start a thread soon to work through some of the details.
For the pre, I'm working from a modded version of Rod Elliotts design (I don't have a problem with opamps):
Attachment 142091

For the power amp, I'll use this:

Attachment 142092

My Abomination amp. It's been laying around since last year without a purpose so I may as well use it here.

I want reverb and left room for the tank.

I did not want to use op-amps for this project because I was trying to follow first principles. Obviously using op-amps would have made my life 1000% simpler, they would just work off the box and they would offer many advantages eg ripple rejection, supply voltage torelance etc. With transistors and FETs the whole design is very fragile, very easy to screw it up, or to get different results because of impedances etc. But I do not regret it, it gives more satisfaction to make something that works this way, it just gets longer to get there

You pre-amp's tone controls are the Fender/Marhall type, almost 100% the same as in my Princeton Chorus amp.

Not sure what the abomination is, I suppose it has been discussed here, it appears to be discrete. Again for my discrete amp project I will again try to follow first principles and see how far it gets me, for example I will have no long tail pair amps and no feedback.

I was also interested in your cabinet looks really slick, mine is much cruder.

[akis]

Originally Posted by Minion

Wow .... Looks nice , Lots of circuitry ... Im also working on a simular project but without the restrictions on opamps , It a 2 channel amp with independant tube preamps and 5 Band active tone controlls and useing 2 x TDA7294 power amp chips (one fort each channel ), I got it set up so I can use each channel independantly with 2 instruments or run one instrument with each channel in paralell ... it"s all home etched stuff accept I am useing a bought Poweramp PCB , still got lots of work to do on it but I got the preamps built and the 5 band eq"s built and the Face plate made .....


again , love yer project !!!

Did you say face plate? Can you show pictures of the enclosure and the face plate?

[Minion]

Originally Posted by akis

Thanks.

Now this is the thing. When you are on stage you will want to switch between many sounds (effects). It does not matter what the amp has built-in, nothing can be as versatile as having an effects console, or a dozen pedals on the floor. Now the effects units have become really cheap. Look at the attached pictures of the Line6 PODxt and the 4 channel footswitch + pedal. This thing is programmable from the onboard knobs or from your PC. You can download effects and program it to do almost anything you like. It is like having many different pedals but it is better because it memorises settings which you can recall at the press of a switch.

I can not even imagine why you'd ever need anything on the amp other than the most clean amplification. No tone controls, no distortions, no crunch, no chorus, nothing at all is needed on the amp. Some amps are like a half-way house, they have some effects built in and provide a foot switch. But nothing can be as advanced as the POD or similar effects consoles. When you are on stage you do not run back and fro to the amp, all you want is at your feet even the volume control.

Now you could say that the "real thing" is the real valve amp which is overdriven to create a particular sound, however the electronic effects come really close that you'd have to be a very serious pro to care. For example I compared the sound between the 19" accutronics reverb springs (best in class) with the reverb from the POD and well if there is slight difference it will be absolutely lost on stage, you'd need to be wearing headphones in a very very quiet room to tell any differences. So why bother.

Of course there are stomp pedals out there which are cr*p, absolutely horrible. Luckily the POD is leagues ahead in quality. We went to the music shop (Andertons) and tried out many pedals and half of them are rubbish and the other half cost as much as the POD each. And they cannot be programmed or anything like that.

Which makes me thing, perhaps for version 2 I should ditch the pre-amp amd tone controls completely - just provide a cabinet with good speakers and good power amps as noone is likely to plug his guitar straight in.

I have a Totally different take on guitar amps and effects ..... I don"t use any effect accept for overdrive/Distortion and Tone controlls (My other DIY Guitar amp has a 15 band EQ) so all I need is a good clean channel and a good extreme overdrive channel and some Versitile tone shapeing , and while I used to be a proponent of Solid state preamps Ive been getting into useing Tubes for getting that compressed squeeling overdrive sound (a la Slayer) .... I guess I"m a bit old school in that regard .....

as for the Pod and other DSP effects processors they are pretty cool and very versitile but there is just sometimg about there sound I don"t like , It"s hard to describe , Like they sound I thin or Lo-Fi , I don"t have much experience with them accept the guitarist for my Band tries one every few months for a while trying to look for his holy grail tone , You figure at 62 he would have found it by now but not yet....lol



Cheers

[MJL21193]

Originally Posted by akis

I did not want to use op-amps for this project because I was trying to follow first principles.

Understandable. Nicely done circuitry, BTW
I use opamps wherever I can to increase SQ and decrease parts count, especially in things like this preamp. They work for me.

Originally Posted by akis

Not sure what the abomination is, I suppose it has been discussed here, it appears to be discrete.

It's an amp project I did last year. Yes, it's a discrete amp - it's a folded cascode design and uses 6 thermal track outputs, very good performance and fairly robust. There is a thread about it.

Originally Posted by akis

I was also interested in your cabinet looks really slick, mine is much cruder.

I put some pics in an album on my profile page. Check it out (and a few other interesting things)

[Minion]

Originally Posted by akis

Did you say face plate? Can you show pictures of the enclosure and the face plate?

Well I haven"t done the enclosure yet (thinking of doing it in the Diamond textured Stainless Steel) but the face plate is done minus drilling the hiles ....


Here"s a Picture of it , I couldn"t get the whole thing in the frame .....






It"s far from perfect but it will suit be fine ....


Cheers

[akis]

Originally Posted by Minion

Well I haven"t done the enclosure yet (thinking of doing it in the Diamond textured Stainless Steel) but the face plate is done minus drilling the hiles ....


Here"s a Picture of it , I couldn"t get the whole thing in the frame .....






It"s far from perfect but it will suit be fine ....


Cheers

What is it made of? Aluminium or steel?

What is the enclosure going to be like? A shoe-box?

The enclosure gave me great headaches. A steel box would be very hard to drill, so I thought of using aluminium, but they were asking about 100 pounds for the most basic U shape. Since I was not sure how everything would fit together I put everything on a plank of plywood. For face plate I used a piece of hardboard and on it a glued printed A4 sheets... It is a big kludge and impossible to drill it accurately. On the next version I might use extched PCBs of the right size.

[Minion]

The Face Plate is Aluminum , it is 6 in x 19 in , so the Box is going to be 17 wide 12 deep and 6 high , the metal shop were I live quoted me $30 for the Stainless steel sides and Top , gonna use a steel bottom and aluminum back to affix the heatsinks ....


Cheers

[akis]

Originally Posted by MJL21193

Understandable. Nicely done circuitry, BTW
I use opamps wherever I can to increase SQ and decrease parts count, especially in things like this preamp. They work for me.



It's an amp project I did last year. Yes, it's a discrete amp - it's a folded cascode design and uses 6 thermal track outputs, very good performance and fairly robust. There is a thread about it.



I put some pics in an album on my profile page. Check it out (and a few other interesting things)

Your wood workign skills are superb. I have a router too, but have not thought of using it to cut out the speaker holes. Or to dig channels into which to slot the panels. What instrument is that attached to the router to make the round holes? Is this an inch thick plywood?

[akis]

Originally Posted by Minion

I have a Totally different take on guitar amps and effects ..... I don"t use any effect accept for overdrive/Distortion and Tone controlls (My other DIY Guitar amp has a 15 band EQ) so all I need is a good clean channel and a good extreme overdrive channel and some Versitile tone shapeing , and while I used to be a proponent of Solid state preamps Ive been getting into useing Tubes for getting that compressed squeeling overdrive sound (a la Slayer) .... I guess I"m a bit old school in that regard .....

as for the Pod and other DSP effects processors they are pretty cool and very versitile but there is just sometimg about there sound I don"t like , It"s hard to describe , Like they sound I thin or Lo-Fi , I don"t have much experience with them accept the guitarist for my Band tries one every few months for a while trying to look for his holy grail tone , You figure at 62 he would have found it by now but not yet....lol



Cheers

During the performance today Alex (my son) used the POD and pedal cointinuously to do fill ins, lead solos, chords, harping, power chords : for every song he has 4 memorised channels and as he also uses two guitars he has fine tuned the POD accordingly, different channels and settings for each guitar. Before every song he selects the correct channel and then during the song he has 4 choices + pedal.

We just kept the amp to "clean" except we could not use my amp, he had to use another band's Marshall amp which was already on stage and all mic-ed up. Shame, my amp never saw live action!

[MJL21193]

Originally Posted by akis

Your wood workign skills are superb. I have a router too, but have not thought of using it to cut out the speaker holes. Or to dig channels into which to slot the panels. What instrument is that attached to the router to make the round holes? Is this an inch thick plywood?

Thanks again

That is my homemade circle cutting jig:

IM001461.JPG

The plywood is cheap 3/4 inch sheathing. I ran it through my thickness planer then lots of sanding to make it smooth.