Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubenit on April 09, 2017, 03:57:16 pm
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I am continuing to experiment with different Dumblish inspired designs where you have a clean and an overdrive channel. The PT on this one is 300-0-300 150ma. A tweed bassman OT would work well with it, I think.
My goal on this one was to use 3 gain stages in the clean channel to try and keep the tone reasonably clean up to 12 noon on the volume dial. I feel like I succeeded reasonably well with this. It has nice full tone to it, IMO and has some musical sweetness in the tone. It is reasonably Fenderish but slightly less mid-scooped.
One of the things that really surprised me was how quite the thing is at idle. Even at volumes beyond what I will normally play at, the idle noise is very very quiet. The original Princeton Reveb I owned once was more noisy at idle then this is. I think it could be easy to walk out of the room and forget to turn the amp off? However, when you hit a chord, it is surprisingly loud.
The overdrive is also to my liking and is very touch responsive with the 5879 tube. I may try tweaking this some more, but if it never got any smoother, I'd still be very happy with it. The 5879 tube does have a little chime inherent in it's tone.
This has more contrast between the clean truly being clean and the overdrive being more boosted & slightly richer tone compared to the clean tone.
Just thought I'd share in case someone is looking for a new idea. Look into the SCH library for editable files.
With respect, Tubenit
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Looks good! Would love to hear some samples.
As always, thanks for sharing.
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Guys, I'm loving this amp! Amazingly quiet at idle. Very musical tone and touch sensitive. Maybe the best clean tone I've gotten out of an amp. The amp is getting a very full tone and good bass with very low volume.
You can get some pretty overdriven tones out of the OD channel, but I am liking it best more like a boosted clean that has richer harmonics and longer sustain. Depending on how you set the 3 OD volume pots you can get some fairly wide range of OD tones.
Editable SCH schematic and layout here: http://el34world.com/Forum/index.php?topic=21804.0 (http://el34world.com/Forum/index.php?topic=21804.0)
with respect, Tubenit
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Looks nice, do you have 225 OD throughout? Have you tried a 12AX7 in V1? Still clean?
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I am using Orange Drop PS everywhere except Musicaps in V1-6, V2-6, V4-2 & V4-6.
I haven't tried a 12AX7 in V1 but have tried a 5751 and it still gives a great clean tone.
I'm using an Emminence Delta-Pro 12A speaker.
with respect, Tubenit