Blues Amp

[tubenit]

I haven't been able to come up with a clever name for this amp. However, this is in my top three favorite amps along with the Carolina Blues Special and DaGeezer's  Little Wing Reverb.

I think it has the best clean tone of any amp I have ever played. It's not a Fenderish clean. It's got a very warm smooth clean tone to it.  Disengaging the NFB and using the PAB, I get a nice overdriven tone with good sustain. I played with a band that had keyboards, acoustic, bass, and drums and the amp cut thru just fine with the mstr vol dialed at around 5 and the volume around 7.


REVISION 6/'09   I changed the V1 plate resistor to 150k which gave me 144v on the 5751 plates which was a sweet spot, tone wise.     Also changed the NFB values to 1.8k/.1uf & 33k.  I got rid of the local NFB loop and instead paralleled a cap to the treble cap for more of a mid boost.

I can get a good clean tone ............. &  with NFB off, the mid boost engaged and PAB engaged .......... it will hold a note for excellent sustain and overdrive.   I also changed V1 and V2 cathode caps to 2.2uf and the coupling cap after V2 to the mstr vol to an Orange Drop .01.  This made the amp less gritty for playing with hotter humbuckers (vs. single coils).  I could not tell that it signficantly changed anything with sustain which remains excellent.

I corrected the schematic to reflect the revisions but have not changed the layouts to reflect them.

Edit 7/24/09: I had an unused triode in the second gain stage. I paralleled it just as I did the V1 tube. It added a fatter tone to the amp with NO increase in idle noise. I like it! No oscillation problems either.

With respect, Tubenit

[tubenit]

Same amp with no reverb.  Using a passive effects loop with digital delay ......... you can get by without missing the reverb.

Check for errors.

With respect, Tubenit

[pullshocks]

I think I have most of what I need to put one of these together, so I am looking at your layout.  It has one feature I have not seen elsewhere--having the reverb circuit at the far end of the chassis and reverb control first on the panel.  Curious why you ended up doing it this way instead of the more conventional placement.

[tubenit]

Regarding the reverb on the end ................. I just kinda got into a habit of doing it that way.

However, I think it's better to be between the LTPI and the gain stages. I redrew it for you but don't have time to double check it tonight.  It's posted above as Blues Amp Layout II. Look over it carefully to make sure it's right, please.

BTW, this has become my most played amp and the one I use most frequently with the band I fill in with. I've gotten some really nice compliments on the tone.

If you want to skip one feature ......... what I'd skip is the local negative feedback. I do use it however,  but don't think it's necessary to get a great tone. It just adds another useful tone but isn't intregal in the design.

Best regards, Tubenit

[pullshocks]

Thanks man.  I swore I wasn't going to build any more amps for a while....guess I'm having a amp lust syndrome relapse

[pullshocks]

Just noticed you are specing a 300--300 PT.  The PT I was planning to use is more like 270-270.  I guess I could partially make up the difference by using a 5AR4 rectifier, but voltages would still be lower.  What do you think, should I give the blues amp a try, or go more in the direction of the Little Wing.

[tubenit]

Whether you build this or a Little Wing or some other amp ............ is your choice & I won't advise you on that.  This is my favorite amp. And other players tend to lean towards the Little Wing.

I am currently using a 5Y3. I also use a 5V4 and a GZ34 in it. They make some tonal differences but mostly in headroom. It still sounds like the same amp.  I'm not sure I could tell which rectifier is in it with a blind test.

I think a 270-0-270 PT would be just fine.

With respect, Tubenit

[imaradiostar]

Maybe it's there and I missed it- what are the pot tapers on the tone controls?

thanks!

jamie

[tubenit]

I think they are audio on bass & linear on mid & treble if I am remembering correctly? However, I am not sure?

Tubenit

[oldgitar335]

tubenit, A newby here. I see that the blues amp has become your most played amp. I built the non reverb version and the only "option" I used was the PAB and sand rectifiers. with weber michigan tens, it does all I need for my band of classic rockers. It has become my main gig amp because of the sound and it's easy on the back also. Thanks for the info for this build. The best tool I have on my bench is this forum. Thanks again.

[tubenit]

Excellent!  Glad you've enjoyed the amp. It's my #1 amp for sure. I love it.

Thanks for the feedback and review.

Best regards, Tubenit