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Post subject: Re: Musicman clone
Posted: Tue Aug 06, 2019 6:39 pm
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ITS ALIVE!!

And it seems stable. I think it sounds good. Have to do more listening tests

The effects are not ready yet. I need to calibrate the Phaser driver.
I received the Accutronics digital reverb module today and found the right molex connectors in my boneyard.
Mouser shipped yesterday, so by the time I get the connectors made up and mount it, I'll be ready for the 16 position selector switch.
I need to rewire part of the reverb circuit now too. The original has some filter networks in the return dircuit to EQ the springs voice. I will be removing the filters to accomodate the digital signal. This is just as well. I had a large negative voltage on the output there. The circuit works. I just can't explain why it would do that.

I also had to reverse the transistors in the overdrive circuit. This is an interesting little circuit. Instead of just clipping diodes, there are a couple high gain transistors in series with the diodes. These would ensure that the transistor controls the turn on of the diodes. This gives a slow clipping action.
Remarkably, it maintains waveshape over a wide frequency range. Most clipping circuits change from a chunky square wave to a triangle wave at high frequencies. This looks like a rounded square wave and just stays that way up and down the octaves.
The Body control worked out well too. The bright switch in the first stage turns on a filter. I added a 1M reverse taper before it grounds. It works like a variable bright control. Its a feature on Evans Amps I liked so I named it the same.

I ttthink I'm gonna like it...


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Post subject: Re: Musicman clone
Posted: Tue Aug 06, 2019 11:21 pm
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Location: Tombstone Territory
TimsAudio wrote:
Remarkably, it maintains waveshape over a wide frequency range. Most clipping circuits change from a chunky square wave to a triangle wave at high frequencies. This looks like a rounded square wave and just stays that way up and down the octaves.


Such a response curve is quite similar to the organic compression and natural saturation of a tube amp design.

Sounds like you've built a winner, Tim.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Musicman clone
Posted: Wed Aug 07, 2019 7:40 am
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Leo built a winner. I'm just lucky enough to have a master builder to emulate.


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Post subject: Re: Musicman clone
Posted: Wed Aug 07, 2019 8:46 am
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Either way, you've earned the kudos.

Rawk on!

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Musicman clone
Posted: Tue Aug 13, 2019 6:42 pm
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https://drive.google.com/file/d/1hHmCYX ... p=drivesdk
https://drive.google.com/file/d/1jVPE3k ... p=drivesdk
https://drive.google.com/file/d/19_RVCm ... p=drivesdk

It's a runner!
The phaser took a little sorting out. I had to trim the drive gain to the reverb module.
I don't know why they would build the module switching the way they do.
There are no bcd switches that count the way they want.
So my switch mixes up the settings. Now I have to redo the front panel lettering.

The noise floor measured 2 divisions on the scope at 1/2 volume. I replaced the TL074s with the TLE2072 and the noise went to .3 divisions. That was good to see.

It has a ton of gain available, but only about 12 watts.
I really like the loops on this. You can plug in the first loop with just a guitar. This bypasses the tone stack for clean tone. It still has reverb and phaser, gain and volume. The second loop can be driven by a pedal and a guitar for the power Amp in.

Now I'm working on the front panel to finish it off.


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Post subject: Re: Musicman clone
Posted: Sat Aug 17, 2019 10:54 am
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https://drive.google.com/open?id=1DMtqVBr0rG7avrewMM-2c0YFavxokk6L
So here is the finished unit. The front panel was printed out on transparency with a clear spray to protect the lettering.

It's not much to look at, but it does rock. I finally got a real guitar player to try it out. The cleans were sparkling and the overdrive creamy. With the phaser and digital delay going, he channeled Robin Trower and we both loved it.
That's not to say its perfect.
The bass is flabby from lack of power. The Deep switch is useless above room volume.
It goes into HF oscillation if all the controls are turned to max. I don't see that as a big problem.
With a one-off layout like I have, there's probably some ground issues that could be straightened out to stabilize it.
The power control on the transformer doesn't seem to lower volume, but it limits max volume. For a transformer that wasn't designed to have DC run through it, it performs better than expected. It does warm up, though. I'm glad its topside.

But overall, it was a great success as well as a good tune up for my next eyelet project, a fully functioning eyelet board for a HRDX

Now if I could only whip these computers into actually displaying my pics instead of links. I've tried Imgur, and oneDrive for a couple days now and despite public settings, all I can get is the link or an image icon. OneDrive gives me a public link that is a url, but either way I try to display it, img or url, it still gives me the image icon and no pic, or it shows the link.
I've tried it on the Android tablet, Windows 10 and a windows 7 computers. Still beat. Good thing I'm an amp tech and not a computer tech. This would be embarrassing


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Post subject: Re: Musicman clone
Posted: Sat Aug 17, 2019 11:58 am
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Joined: Sat Dec 13, 2014 7:34 am
Posts: 245
You should plug an acoustic into your amp as well Tim, just to see.

UN


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Post subject: Re: Musicman clone
Posted: Sun Aug 18, 2019 7:45 am
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I want to put it through its paces on a number of instruments.
I built it with a steel guitar in mind. Its very low gain, so I think it will sustain very nicely. So an acoustic should sound good too.


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