Electro Harmonix "Big Bottle" 6CA7's
Posted: Tue Aug 04, 2020 1:36 pm
Has anybody swapped out their skinny bottle EL34's for the Electro Harmonic "Big Bottle" 6CA7's?
Years ago, I had a 1975 (first year issue) Marshall Master Volume, known as the 2203. The band I was in also played some "clean" songs as well as those with overdrive. After having the amp re-biased from the OEM 6550's to EL34's, that was a help, but occasionally even that was a little to much grit. So with the help of my tech, we researched and found the Electro-Harmonix "Big Bottle" 6CA7's. Now in the meantime, I also had a set of original Sylvania 6CA7's, which do have different plates and a couple more internal differences to the EL34's, Mullard style, but pin-out and bias the same.
WOW!!! I got all the same overdrive when the song called for it, but when I backed it off, it had a sweetness and shimmer that just does not happen with EL34's, but a more robust tone than 6L6GT's. Alas, that amp finally died, and I thought that was that.
Fast forward twenty years. Marshall has a fairly new amp called the Origin 50. The controls were reminiscent to my old amp and its 50-watt companion, the 2304. I bought one. Yes, it had the same midrange push my old amp had all those years ago before changing power tubes; otherwise, the tone stack was IDENTICAL in tone, even to the "Tilt" knob, which is essentially a variable bright control, which I had modded my 2203 to have the same control over the input jack all those years ago.
Yeah, I had to: I found a matched pair of new Electro Harmonix "Big Bottle" 6CA7 tubes and ordered them. Serendipity. When I opened them, and took out the pair of EL34's, both pairs were labelled with identical biasing ratings, so I didn't have to call my friend to re-bias my amp!
Tone: I HAVE MY TONE BACK!!! They have that same sweetness I had all those years ago, overdrive when called for, and the same tonal characteristics from the tone stack. AHHHH!!! Oh, yeah - you should hear my Rick 12 jangle through it!!!
Bottom line: if you want more sweetness out of your amp than EL34's, try the Electro Harmonix "Big Bottle" 6CA7's: same plates as 6550's, more robust than 6L6GC's, bias the same as EL34's, and, at least to my ears, more headroom for a bigger tone.
Years ago, I had a 1975 (first year issue) Marshall Master Volume, known as the 2203. The band I was in also played some "clean" songs as well as those with overdrive. After having the amp re-biased from the OEM 6550's to EL34's, that was a help, but occasionally even that was a little to much grit. So with the help of my tech, we researched and found the Electro-Harmonix "Big Bottle" 6CA7's. Now in the meantime, I also had a set of original Sylvania 6CA7's, which do have different plates and a couple more internal differences to the EL34's, Mullard style, but pin-out and bias the same.
WOW!!! I got all the same overdrive when the song called for it, but when I backed it off, it had a sweetness and shimmer that just does not happen with EL34's, but a more robust tone than 6L6GT's. Alas, that amp finally died, and I thought that was that.
Fast forward twenty years. Marshall has a fairly new amp called the Origin 50. The controls were reminiscent to my old amp and its 50-watt companion, the 2304. I bought one. Yes, it had the same midrange push my old amp had all those years ago before changing power tubes; otherwise, the tone stack was IDENTICAL in tone, even to the "Tilt" knob, which is essentially a variable bright control, which I had modded my 2203 to have the same control over the input jack all those years ago.
Yeah, I had to: I found a matched pair of new Electro Harmonix "Big Bottle" 6CA7 tubes and ordered them. Serendipity. When I opened them, and took out the pair of EL34's, both pairs were labelled with identical biasing ratings, so I didn't have to call my friend to re-bias my amp!
Tone: I HAVE MY TONE BACK!!! They have that same sweetness I had all those years ago, overdrive when called for, and the same tonal characteristics from the tone stack. AHHHH!!! Oh, yeah - you should hear my Rick 12 jangle through it!!!
Bottom line: if you want more sweetness out of your amp than EL34's, try the Electro Harmonix "Big Bottle" 6CA7's: same plates as 6550's, more robust than 6L6GC's, bias the same as EL34's, and, at least to my ears, more headroom for a bigger tone.