Hi-Gain SE

roberto · Post by **roberto** » Thu Oct 02, 2014 7:32 am

Take a look at the attached file: split load and frequency shaping.

angelodp · Post by **angelodp** » Sat Oct 04, 2014 9:40 pm

Thanks for those notes Roberto. I am working my way towards implementing some of these ideas. In the meanwhile, I wanted to post some voltages based on the actual point to point build which has a 12at7 in V1 and 12ay7 in V2. I also pulled the tone stack and tried a typical Fender blackface stack without a slope pot, rather a 100k fixed resistor. I went back to the Merlin tone stack and preferred that for now. I did implement the RAW control. All in all a good sounding amp with some very useable tones. I do want to extend the headroom as well as get into more complex overtones in the gainey sounds. The layout represents what I might do on the next build instead of point to point. And in fact this is the next iteration of this amp with a proper layout.

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802]http://i260.photobucket.com/albums/ii9/angelodp1/1801-25-Master-pin-swap2_zps00ab14d0.jpg[/img]

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834]http://i260.photobucket.com/albums/ii9/angelodp1/565-redo-pin-swap-boostMV_zpsc9ea3845.jpg[/img]

angelodp · Post by **angelodp** » Sat Oct 04, 2014 9:48 pm

Here is the P to P build - don't laugh too loud… it works and almost no noise level on hum buckers. This was a rework of the original amp that was used in an editing system.

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768]http://i260.photobucket.com/albums/ii9/angelodp1/IMG_0439_zps1631388c.jpg[/img]

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768]http://i260.photobucket.com/albums/ii9/angelodp1/IMG_0438_zps7fcd7dda.jpg[/img]

ChrisM · Post by **ChrisM** » Sat Oct 04, 2014 9:51 pm

roberto wrote:Take a look at the attached file: split load and frequency shaping.

Very interesting stuff

How are you calculating the corner frequency for 2nd and 3rd cases?

angelodp · Post by **angelodp** » Wed Oct 08, 2014 3:41 pm

Ok I threw in the 82k/22k voltage divider at V1a going into the .02uf that leads to the gain pot. That knocked back the AC signal by 2/3rd I reckon. That did help significantly with the high levels I was getting. Going to throw in a 12ax7 and see what that feels like.

Similar issue I had prior, which led me to the 12AT7 in V1, I get high end oscillation when the volume pot gets rolled up with the gain pot up full. This could be a lead dress issue as this point to point has a lot of nasty wiring convergences going on.

Went back to earlier configuration with 12At7 as this voltage divider setup hanging in the air was no bueno. I will revisit this with the next chassis that has a proper board and avoids some of these lead dress issues.

A

angelodp · Post by **angelodp** » Fri Oct 24, 2014 10:54 pm

Ok, she's up and running. Its a 4 gain stage Champ w/ boost and RAW and variable NFB . It operates on 12AT7 in V1, 12AY7 in V2 and then 6V6 and 5Y3. It goes form a great clean tone all the way to OD madness. Dime'd it with a Strat and a Tele and it has a wonderful breakup with feedback howl if you want it.

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768]http://i260.photobucket.com/albums/ii9/angelodp1/IMG_0457_zps101bcc29.jpg[/img]

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768]http://i260.photobucket.com/albums/ii9/angelodp1/IMG_0456_zps36619a46.jpg[/img]

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768]http://i260.photobucket.com/albums/ii9/angelodp1/IMG_0453_zpsb01d5aea.jpg[/img]
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M Fowler · Post by **M Fowler** » Sat Oct 25, 2014 3:45 am

Nice Angelo, that old blue perf board is perfect for this project.

Mark

angelodp · Post by **angelodp** » Sat Oct 25, 2014 4:43 am

Thanks Mark, its does have some similarities to the Swampthing circuit. Lots of fun and quite a range. I may get brave and pop in some 12ax7's tomorrow, maybe throw this into series oscillation. Try and get some clips up soon.

phalanges · Post by **phalanges** » Sat Oct 25, 2014 5:04 am

I did some test piloting and I'm happy to report that this build has the goods.
It can only improve as fine tuning ensues.

Smokebreak · Post by **Smokebreak** » Sat Oct 25, 2014 1:09 pm

Very cool amp! I'm looking forward to some clips. The split load shaping is really intriguing, too. More reading on the subject : http://www.ax84.com/bbs/dm.php?thread=297726

angelodp · Post by **angelodp** » Wed Nov 05, 2014 5:10 pm

Hi, thanks for the kind words. I updated the layout and schematic to more accurately reflect the build.

Structo · Post by **Structo** » Wed Nov 05, 2014 7:20 pm

Stupid question but, is the Raw control simply a NFB type control like a presence control without the capacitor?

That seems like a cool thing to be able to control the NFB.

I have a switch on my Dumble clone for NFB on or off.
Really opens up at lower volumes when the NFB is off.

angelodp · Post by **angelodp** » Wed Nov 05, 2014 8:09 pm

I believe that it allows the signal to bypass the tonestack, sort of like the PAB. Adds a rich OD sound. The Encore amp has it.

tubeswell · Post by **tubeswell** » Wed Nov 05, 2014 10:54 pm

Structo wrote:Stupid question but, is the Raw control simply a NFB type control like a presence control without the capacitor?

Raw control (in most amps) is a 1M or so pot between the ground return and the tonestack that effectively removes the tone stack from the signal path (when the raw control is dimed). It works by lessening the AC load on the gainstage that is the source stage for the tone stack, whereby the signal loses the RC-filtering (and the attenuation) that the tone stack would otherwise provide. Thus the signal becomes more 'natural' (or raw). This is quite different from a presence control which alters active NFB

angelodp · Post by **angelodp** » Wed Nov 05, 2014 10:57 pm

I also have NFB control on the rear of the amp 50KB pot, which also lends a more dirty sound to the amp.

Tube Amp Archive

Hi-Gain SE

Re: Hi-Gain SE

very interesting

p tp p

Re: Hi-Gain SE

82k-22k

It lives

Re: Hi-Gain SE

Swamp thing

Re: Hi-Gain SE

Re: Hi-Gain SE

thanks

Re: Hi-Gain SE

RAW

Re: Hi-Gain SE

my amp