Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: lkrasner on March 17, 2015, 09:59:06 am
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I'm looking to run a 6v6 and el84 in parallel, but I'd like to preserve the option of running a single octal tube if possible (6v6, 6L6, KT77, maybe KT88, etc..). I'm kind of struggling to find an OT for this.
For the 6v6/ el84 pair, I think I need a primary of about 2.5K, but the other tubes need approximately twice that. I believe I need to be able to handle over 100mA dc, which is rather limiting I'd also like to have taps at 4, 8, and 16 Ohms if possible on the output. I know some transformers (like the hammond 125 series) let you simply change which output tap you are using to multiply the primary, but many others do not recommend this.
Anyone have some suggestions of something that would fit my needs? Preferably in the $100-$200 range, but that is possibly flexible.
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Running the parallel 6V6/El84 would be fine with a primary around 4 to 5K. A single octal such as a KT88 would work as well. If cathode bias your cathode resistor would need to vary to achieve full output potential.
You really need to get more specific with voltages. I usually get these from Edcor. Look at their website at the SE offerings. You may have trouble getting a multitap from them. They are quite a good value.
A lot of times you will find just changing the output tubes really doesn't change your tone much, just distortion characteristics.
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Running the parallel 6V6/El84 would be fine with a primary around 4 to 5K. A single octal such as a KT88 would work as well. If cathode bias your cathode resistor would need to vary to achieve full output potential.
You really need to get more specific with voltages. I usually get these from Edcor. Look at their website at the SE offerings. You may have trouble getting a multitap from them. They are quite a good value.
A lot of times you will find just changing the output tubes really doesn't change your tone much, just distortion characteristics.
I'm planning on building variable bias, so that's not an issue.
I will run the output section around 300-350V, basically near the EL34 limit, but people run those way high all the time, so I'm not too worried.