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Heretical 5E3 idea?

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  • Heretical 5E3 idea?

    I have an old console (not collectible - no value) full of donor parts, including PT and P-P OT. I've been considering what to build from it and I'm thinking an idea that is probably going to be ridiculed, but might be interesting. The idea is to construct a 5E3-style amp using a pair of 35C5 for the output section. I'm thinking this might provide a similar sound and interactivity, but at much lower "bedroom" levels. I do realize that these tubes are not 6V6s and will not sound exactly the same, but may be worthwhile as long as I keep the plate voltages at the proper levels so they don't get into the "nasty" distortion zone.

    Has anybody here's done anything similar to this, or done a P-P 35C5 amp that could provide opinions about whether this is worthwhile? If it's generally considered to be a worthless endeavor, I may just make it more of a Marshall-style setup - with high gain, who really knows what the output tubes are...

    Oh yeah, if the 35C5's are worthwhile with the 12AX7 as PI, I may consider using the existing 17EW8 as the dual-triode preamp (lower-gain for more headroom and less overall distortion) to go along with a series-string heater arrangement (the PT is an isolation xformer, so voltages will be <200 throughout). There's another issue - lower voltages on the preamp and PI may not be usable, but maybe still usable.

    So, any comments or opinions, or will I be banned from this section of the forum for my heretical thoughts?

  • #2
    A pair of 35c5's in an amp such as you propose would probably be good for 8W to 10W. That's not really bedroom levels. The need to use a series heater string is a limiting factor. So why a 5e3 type circuit or topology? You could instead maximise for the tubes you must use to accomodate the heater string. IMHO trying to make a 5e3 with a set tube criteria that doesn't match is like like trying to make chicken soup from beef stock. That isn't to say that a 5e3 type topology won;t work and sound good with your tube line up. Just that it won't be a 5e3. And I'm sure by the time the amp is tweaked to your liking it REALLY won't be a 5e3. But sans designing the gain blocks from scratch I suppose you do need to start somewhere.
    "Take two placebos, works twice as well." Enzo

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A


    • #3
      Yeah, I'm not going for an "authentic" 5e3 clone...just a similar setup that I can experiment on and play with the interactive controls to approximate what happens on a real 5e3. I'm surprised by that power output...I was under the assumption that 35c5 P-P with <200VDC would be more like 3-5W. Oh well, maybe I should just focus on my DuKane projector conversion (5e3-type circuit using 6AQ5 - much closer to "normal") for a lower-power setup.