JJ Split Personality Rescue
It's All About The Tube, 'Bout The Tube, 'Bout The Tube
I finally have my Marshall DSL15c dialed in. Stock, it sounded weak, the speaker sucked, the tone was off, the ultra-gain channel was only good for bone crunching metal, and the clean channel was anemic.
I made a few resistor and capacitor changes, put an old Celestion G12H Anniversary speaker that I had laying around in it, put TAD 6v6 tubes in the power section, and tried a JJ 5751 in the V1 with Tungsol 12AX7 in the other two pre-amp slots and the phase inverter.
After those changes, the ultra-gain channel was much better, but still had too much gain when I had the gain knob beyond 3. It was usable though. The problem was that the Clean channel was even weaker than before.
So I searched and searched the internet and learned about the JJ ECC823 pre-amp tube. The ECC823 is 12ax7 style tube. One of the things about 12ax7 tubes is that they are actually two tubes in one (two separately functioning sides). With the Marshall DSL15c, they use one half of the V1 tube for the Clean channel, and the other half for the Ultra-Gain Channel.
The beauty of the JJ ECC823 is that the half that the Clean channel uses is a full gain 12ax7 which delivers 100% gain, while the other half is a 12au7, which has about 20% gain, which tames the Ultra-gain channel
I moved the JJ 5751 from V1 to the Phase inverter slot and dropped the JJ ECC823 in V1. The reason for moving the JJ 5751 to the Phase Inverter instead of keeping the 12ax7 is that the 5751 is military spec and peaks at 70% gain, rather than pushing to the full 100% like the Tung-Sol 12ax7 does. The thought was that not pushing the signal as hot into the power tubes, while retaining the gain achieved in the first three pre-amp stages would provide a little overhead without hurting the tone or pushing the power tubes as hard.
The tube layout is now this:
V1: JJ ECC823
V2: Tung-Sol 12ax7
V3: Tung-Sol 12ax7
V4 (Phase Inverter): JJ 5751
Power Tubes: TAD 6V6
OH YEA!!!!!! The clean channel is full, warm and clear with a little edge, and the Ultra-Gain Channel has been tamed, for some sweet JCM800 tones, instead of bone crunching.
My work on the Marshall DSL15c is done.
I finally have my Marshall DSL15c dialed in. Stock, it sounded weak, the speaker sucked, the tone was off, the ultra-gain channel was only good for bone crunching metal, and the clean channel was anemic.
I made a few resistor and capacitor changes, put an old Celestion G12H Anniversary speaker that I had laying around in it, put TAD 6v6 tubes in the power section, and tried a JJ 5751 in the V1 with Tungsol 12AX7 in the other two pre-amp slots and the phase inverter.
After those changes, the ultra-gain channel was much better, but still had too much gain when I had the gain knob beyond 3. It was usable though. The problem was that the Clean channel was even weaker than before.
So I searched and searched the internet and learned about the JJ ECC823 pre-amp tube. The ECC823 is 12ax7 style tube. One of the things about 12ax7 tubes is that they are actually two tubes in one (two separately functioning sides). With the Marshall DSL15c, they use one half of the V1 tube for the Clean channel, and the other half for the Ultra-Gain Channel.
The beauty of the JJ ECC823 is that the half that the Clean channel uses is a full gain 12ax7 which delivers 100% gain, while the other half is a 12au7, which has about 20% gain, which tames the Ultra-gain channel
I moved the JJ 5751 from V1 to the Phase inverter slot and dropped the JJ ECC823 in V1. The reason for moving the JJ 5751 to the Phase Inverter instead of keeping the 12ax7 is that the 5751 is military spec and peaks at 70% gain, rather than pushing to the full 100% like the Tung-Sol 12ax7 does. The thought was that not pushing the signal as hot into the power tubes, while retaining the gain achieved in the first three pre-amp stages would provide a little overhead without hurting the tone or pushing the power tubes as hard.
The tube layout is now this:
V1: JJ ECC823
V2: Tung-Sol 12ax7
V3: Tung-Sol 12ax7
V4 (Phase Inverter): JJ 5751
Power Tubes: TAD 6V6
OH YEA!!!!!! The clean channel is full, warm and clear with a little edge, and the Ultra-Gain Channel has been tamed, for some sweet JCM800 tones, instead of bone crunching.
My work on the Marshall DSL15c is done.
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