Comments on: A Blues Harp Guide to Amplifiers – Tube Configuration

By: Keith

Keith — Sat, 06 Aug 2011 17:36:45 +0000

The 83s are the same as 12AX7s. They may be a little too much gain for harp. EL84s are used in lots of low end amps in the 60s, about the same watts as a 6L6, perhaps a bit less, but more than a 6V6..

I’m thinking low end Marshals since you are using the British notation on the tubes. You would see lots of mid 1960s Danelectro, Harmony and Silvertone amps with this configuration. Many were run hot to get lots of gain for guitars and sound harsh with lots of overdrive distortion.

Keith

By: Pete

Pete — Sat, 06 Aug 2011 16:03:33 +0000

2x ECC83 Preamp Valves
1xEL84Power Amp Valves

What are your thoughts on this configuration?

By: Keith

Keith — Fri, 13 May 2011 18:58:25 +0000

What about SAG?

By: Roy

Roy — Fri, 13 May 2011 18:53:32 +0000

“Solid State: It’s a bad idea.”
Simply NOT true. The rectifiers influence on the sound is next to nothing and they are notoriously unreliable, whereas a solid state rectifier has none of the reliability issues and provides faster response to current demands – it’s a little like vinyl vs CD: romantic myth vs hard science fact. Solid state RECTIFIER: It’s a great idea. Otherwise solid state stinks.

By: Robert Marsella

Robert Marsella — Thu, 17 Mar 2011 18:33:51 +0000

I am not an engineer,however, I do know how to read. The info on lowering the gain on the preamp tubes can be found on Dennis Gruenings site “bad ass harp”,
also on “Greenbulletmics.com”, and on,” Good tone in amplified harmonica playing”. This is common knowlege in the blues community. Enough said.

By: Keith

Keith — Sat, 19 Feb 2011 04:26:02 +0000

BUT…
If you put in a lower gain preamp tube, the amp isn’t as loud. Sure, you can turn up to 6, now, but the amp is no louder than it was on 3 with the hot tube.

Keith

By: Robert Marsella

Robert Marsella — Sat, 19 Feb 2011 04:07:00 +0000

I was taught that if you can’t get the amp volume knob over3 without it feeding back, then the easiest fix is to change out the 12ax7 to a tube that has a less gain factor. For example, a 12ax7 has a gain factor of 100. If you get feedback with amp on 3 or 4 than change to a 12at7, with gain factor of 70.
If still not good enough, 5751 has gain factor of 60.Going to a lower gain reduces loudness of amp, but you can turn it up more. 12ay7 gain factor 40.
Sometimes I have come across such a hot amp that I cannot use a JT30,or even Green bullet. This is wear the lowering of the gain will let you use your favorite mic. Hope we are on the same page here, I am just trying to help.
Harp Rob