New amp - the Stratifier

[abecknell]

Hey Everyone,

I'm Alan from Ellicott City, MD. Been lurking here for quite a while and have to say a huge thanks to all of you for all the great information you provide.

I have been interested in the Dumbles for years but mostly I play lower wattage amps. So I decided to build Honeydip's Violeta amp - the single ended EL-84 amp with the D-style pre.

https://tubeamparchive.com/viewtopic.ph ... highlight=

Upon completion I tried the amp with all my speakers and guitars. The immediate positives were the sustain and the way notes would hang, the touch sensitivity, and the clean tone with my strat, particularly through my Weber ceramic Signature 12 speaker. On the down side, to me the OD channel was quite bright and harsh and I felt that humbuckers had too much of an edge on the OD channel.

So, the mods started. I decided to sculpt the amp for the Weber Sig 12 ceramic speaker (which is a great value at just over $40) and single coil Fender style guitars. Here is sort of the path I followed:

1. Replaced both 12AX7's in the preamp with 12AY7's (new EH's).
2. Reworked Honeydip's "Mild" control on the OD channel to be a much more significant Low Pass shelving filter to mellow the OD harshness. I just call it OD Tone now.
3. Added switchable coupling caps between the first tube and second tube to control the amount of bass frequencies sent to the OD channel. I call it the OD Fat switch, which I labeled "Off - Medium - Max" fatness. Max fatness is the original Honeydip circuit.
4. Added a Dana Hall VVR board to allow dialing back the volume while maintaining tone. This worked so well that I changed the existing Master Volume to a clean volume so that the balance between the clean and OD channels can be easily set.
5. Added a slight treble cut to the clean channel and labeled it the bright switch.
6. Added a Weber low power switching relay board for footswitching bewteen the clean and OD channels (there is a front panel switch too that works when the footswitch is not plugged in).
7. Added a resistor to the bottom of the OD level pot. This prevents you from going to zero volume for the OD channel (who would need to?) but gets a little more output delivered to the Power Tube.

The result is very cool, I think. I have loaned it to several friends now and everyone really enjoys it. It is still a single coil, Strat and Tele kinda amp - hence my name for it. Think "blues machine". The clean sound definitely impresses everyone - especially if you hang it on the edge of starting to break up - you know, the "warm clean" thing - both by cranking the preamp gain and by pushing the power tube a little. The only disadvantage when you get really into the "pushing the power tube thing for warm clean" is that the OD channel is slightly lower volume than the clean channel. Weird, but I remember Honeydip noticing something similar in his amp. However you can get a great match between the OD channel and a clean tone that doesn't push the power tube much and it sounds excellent on both channels.

Schematic should be attached and I have the .sch version if anyone wants it. Sound clips and pics and all are at my website on the Stratifier page:

http://www.maizingrayz.com

Thanks again,

Alan

[xtian]

Great work, and welcome!

[10thTx]

Yes, I very much would like an SCH version.

AND ............ IF you are OK with it, let's put it in the D-inspired amps:

https://tubeamparchive.com/viewtopic.php?t=17500

Thanks, 10thtx

[Phazor]

Great Little Amp. Great Results. Love the clips.

[abecknell]

Thanks for the comments guys!

10thTx: Here is the .sch file, and please feel free to move the files wherever you think they make sense. I never did a layout, sorry.

Alan

[10thTx]

Thank you for the SCH schematic. It will go into the D-inspired files.

With respect, 10thtx

[xtian]

Alan, I cannot find info on Hammond 169ex. Typo?

And what primary impedance on your OT did you choose?

Thanks!

[da Geezer]

Maybe he really used this(?)....the 269EX

http://www.hammondmfg.com/pdf/EDB269EX.pdf

G

[abecknell]

DANG! You look at something a hundred times and it looks right ....

Yes, power tranny is the Hammond 269EX.

Primary impedance on the Heyboer was 6K (blue wire). Unfortunately, it looks like Chris is out of them temporarily at Doberman.

Revised schematic attached.

Thanks for catching that - sorry.

Alan

[Structo]

Sounds really good.

Congrats on the build.