Custom ss guitar amp build!

[mgcasella]

I found someone locally (a guy named Tom) who will build a ss guitar amp for me and I am psyched

Last week I met with Tom and we ironed out all the details of the amp.  Upon meeting, he realized that my design was a little more complicated than he thought (I wasn't able to communicate all that I wanted clearly via email because I'm not an electronics engineer).  In a few days, Tom should be getting back to me and, hopefully, we'll be ordering the parts pretty soon.

Tom said this whole project should take about one month so I'll keep everyone updated on the progress  :tu:

[mensur]

I found someone locally (a guy named Tom) who will build a ss guitar amp for me and I am psyched

Last week I met with Tom and we ironed out all the details of the amp.  Upon meeting, he realized that my design was a little more complicated than he thought (I wasn't able to communicate all that I wanted clearly via email because I'm not an electronics engineer).  In a few days, Tom should be getting back to me and, hopefully, we'll be ordering the parts pretty soon.

Tom said this whole project should take about one month so I'll keep everyone updated on the progress  :tu:

What kind of amp, how much power, channels...?

[J M Fahey]

*Where* is

locally

?

[mgcasella]

I am in Lawrence, Kansas   <3)

Here are the features so far:
-The design is based off a few common favorite ss amps that are specifically good for METAL (such as the Ampeg VH-140C [LOOSELY, that is]) plus the addition of extra controls and features (such as a "Depth/Resonance knob)
-100 watts
-----I was skeptical about just having 100 watts but Tom assured me he knew what he was doing.  He also said if I wasn't completely satisfied then we would tweak it until I was or I didn't have to pay him  :tu:
-Two inputs:  High gain and Low gain
-Two channels:  Clean, and Distorted (plus a Boost switch for the second channel for soloing, getting even more gain if you are doing straight up grindcore/noise, etc).
-Two output jacks with a choice of 4, 8, or 16 ohms
-Direct line out
-Effects loop
-Reverb (because everyone knows you sometimes just need a little bit of it
-Master volume

My goal is to make a high quality amp that is specifically for METAL \m/ (and that includes all sub-genres).

If anyone can think of any other "must-have" features then please let me know!  This is still in the design stage so there is still time to include them.

[J M Fahey]

For one, forget about

-Two output jacks with a choice of 4, 8, or 16 ohms

unless it's a tube amp, which I guess it is not.

[teemuk]

But that can be achieved. Either by fitting an autotransformer to output for impedance matching, or by varying the power supply rail voltage + power amp gain according to preferable impedance setting.

[mgcasella]

It's been a while - this I know   but we (Tom and I) are waiting on some stuff to come in the mail. For the purpose of experimentation we are going to be trying two different chips (TDA7293 and LM3886T) in the power section. By this, I mean we are going to try the TDA7293's in the amp first to see how they sound, and then see how the LM3886T's sound.

If anyone knows anything about these chips that we should know (that we wouldn't get from a simple Google search), and has an opinion on them, please speak up. Also, don't worry, there will be plenty of ventilation/airflow/heat-sinks as Tom said these things can get pretty hot  :trouble

BTW the amp is now officially planned to put out 150 watts.

PS: If anyone has a good schematic of the Mosvalve MV-962 please send it to me because Tom wants it  :tu:

[phatt]

Hi mgcasella,
                You may need to clarify the 150Watts? (Headscratch)
If that's what you expect to get from an LM3886T ,,then I have bad news as the best is about 50W @8R.

That said it is a stunning little chip and well suited for guitar in my recent findings.

I'm Having an absolute ball working with this little throw away.

See here:
http://www.ssguitar.com/index.php?topic=1672.0

Contains an LM3886T running from 36-0-36 VDC Rails.

I have not updated the progress as there has been a distinct lack of replies but if you wish I'll post the schematic of PowerAmp circuit and little Preamp I hooked up.

I only wanted to utilise a 2 knob preamp as all my fancy stuff is done via outboard preamps so I only need simple control over the poweramp chip section.

The wacky thing is it does a wonderful compression job of guitar signals  and I'm still looking into why that may be so but for the moment I'm having so much fun playing it I don't wish to pull it apart.

From what I've found so far;
If you want all clean power at 50Watts then don't bother with the LM3886 as it distorts when driven.  which is exactly what I wanted. A cheap little amp that breaks up nice,,,
I'm chuffed. <3)
Cheers Phil.
Edit: I should add it's friggin loud when you plug into a 15 speaker

[Jack1962]

brother I would go with the TDA7293's , they work real well , and can produce the power that your looking for , check out the Marshall AVT

                                                    Rock On

[mgcasella]

Hi mgcasella,
                You may need to clarify the 150Watts? (Headscratch)
If that's what you expect to get from an LM3886T ,,then I have bad news as the best is about 50W @8R.

That said it is a stunning little chip and well suited for guitar in my recent findings.

I'm Having an absolute ball working with this little throw away.

See here:
http://www.ssguitar.com/index.php?topic=1672.0

Contains an LM3886T running from 36-0-36 VDC Rails.

I have not updated the progress as there has been a distinct lack of replies but if you wish I'll post the schematic of PowerAmp circuit and little Preamp I hooked up.

I only wanted to utilise a 2 knob preamp as all my fancy stuff is done via outboard preamps so I only need simple control over the poweramp chip section.

The wacky thing is it does a wonderful compression job of guitar signals  and I'm still looking into why that may be so but for the moment I'm having so much fun playing it I don't wish to pull it apart.

From what I've found so far;
If you want all clean power at 50Watts then don't bother with the LM3886 as it distorts when driven.  which is exactly what I wanted. A cheap little amp that breaks up nice,,,
I'm chuffed. <3)
Cheers Phil.
Edit: I should add it's friggin loud when you plug into a 15 speaker

Thanks for the info :tu:  As far as the 150 watts is concerned, since I'm not the engineer building this, I'm not quite sure how to answer your question    However, I'm sure Tom (the tech) will know.  Whether he'll have time to respond, however, that's another matter 

BTW even though I don't understand the technicalities behind your project I'm definitely going to check out your thread  :tu:

[joecool85]

From what I've found so far;
If you want all clean power at 50Watts then don't bother with the LM3886 as it distorts when driven.  which is exactly what I wanted. A cheap little amp that breaks up nice,,,
I'm chuffed. <3)
Cheers Phil.
Edit: I should add it's friggin loud when you plug into a 15 speaker

I disagree on the breakup, that must have something to do with your circuit.  My LM3886 was clean all the way up to full volume, and VERY loud with the 10" speaker I had on it.  Loud enough that in a 14' x 16' bedroom I couldn't play above 1/2 volume, and even that left my ears ringing.  It comfortably played with a full drumset around 1/2 to 3/4 volume.

[phatt]

Thanks for the input Joe Cool,

Well all very interesting, but rather frustrating for me.
I hate it when something works great but you have no clue as to WHY!
Drives you crazy :duh

I will soon post the preamp and my scratchings of how the Pwr chip is wired up.

I hotwired a Trademark 60 a while back and that uses the LM3886.
It was clean and loud but crap distortion.
I assumed all the comp/dist/OD effect was in the preamp.
(and you can't access the Pre circuitit as it's one big blob of black plastic)
Cheers, Phil.
                 

[phatt]

Hi ,, I just posted some circuits here;
http://www.ssguitar.com/index.php?topic=1672.msg11002;topicseen#new

Might give some ideas to work with.
Phil.

[Jack1962]

Nice schematic phatt , and looks like a pretty good power stage to me.

                                               Rock On

[mgcasella]

Hello Everyone!

Sorry - I know it's been a while.  Unfortunately, since Tom and I are very busy making money so we can eat and pay rent, we do not have the ability to devote 100% of our time to this lol

To tide everyone over, I decided to post some pics of when I visited Tom's place.  I was unable to get any good pics of the outside so I may take some when I visit this week.  Apparently, this used to be THE place to party back in the 80's here in Lawrence, Kansas but (unfortunately) I didn't take pics of the entire place - just Tom's work space.  Seriously though - this place has a fucking balcony and everything \m/


This was my first view when I came down the stairs   


The pool table.
Whoever can find Tom's leg first gets a prize!   :tu:






The bar.






Tom's desk.




Tom fixes keyboards for people, and it is also his main instrument, so he has a lot of them hanging around.


Cigarettes, PCB, schematics, calculations I don't understand, and a subtext of METAL \m/

Some people would be alarmed if their technician's workspace looked like the preceding pics, but not me.  This is because, if it wasn't for the fact that I have a small apartment as well as a roommate, my place would look exactly like this too 

I will be meeting with Tom later this week and he will be showing me some IC chips, as well as a power transformer, that we will possibly be using. 

Don't despair - more updates should be coming shortly!