FerdinandII wrote:
I'm planning to use triodes in push-pull, so anything 5k Plate-to-Plate and above would work.
4 and 8 ohm taps on the secondary would be ideal.
4 and 8 ohm taps on the secondary would be ideal.
Do you plan to use true triodes or triode-strapped pentodes/beam power tubes? Feedback or no feedback? Is there a schematic you have in mind, or are you going to try something from scratch?
I ask because I have a number of options here I won't get around to using, but it depends on what you plan to build. I've got a pair of Eico HF-22/35 OPTs, 7500 ohms p-p with 43% UL taps, with 4, 8 and 16 ohm outputs. They can do 25 watts. They'd probably afford the best bandwidth for a no-feedback amp. They're big, they're potted, they need repainting and the leads will need to be extended, but they're in good condition (or were the last time I checked).
I've got a pair of Heathkit W4 OPTs, 10K p-p with 4, 8 and 16 ohms taps, good for 20 watts. These are small and potted, very nice little trannies, but I've never measured them without feedback. They'd probably do okay without it. I have an accompanying schematic for a swell 10wpc triode-strapped EL34 amp that is very zippy. You can see the project here:
https://audiokarma.org/forums/index.php ... ld.795322/
And then I've got a pair of Sophia Electric OPTs from a Sophia stereo p-p EL34 amp that someone trashed with extensive (and unreversible) modifications. I rebuilt it as a PP stereo 300B amp but it wasn't impressive enough to dwell on, and I'm not interested in buying 300Bs anymore.
If they're what I think they are, they're 5.5K p-p with 4 and 8 ohm taps, and Sophia still sells them for $700/pair. No split primary, and plate taps only. They're potted. These might actually be the best thing for your project if you plan to use true triodes and no feedback. I could throw them on my "hacker" amps and see what the bandwidth looks like with no feedback. You're welcome to these, I have no use for them, they're just sitting here.
