Hello! Just picked up an as is Presto K8 and am looking to use a modern amp on it. Where do I need to reroute things in the schematic so I can use a modern amp to drive it, and what tubes would I still need, if any?
Thanks!
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Bypassing the amp on a K-8
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Bypassing the amp on a K-8
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Re: Bypassing the amp on a K-8
Also, what type of solid state amp would you recommend?
Re: Bypassing the amp on a K-8
Hi,
Just connect right to the wires going to the cutter head. No need to get into the K8 amp at all. Any 50 watt or greater mono amp will do fine. Might want to put a in line fuse holder and start with a 1/4 amp fast blow fuse until you get the hang of how much power you can throw at the head.
Mark
Just connect right to the wires going to the cutter head. No need to get into the K8 amp at all. Any 50 watt or greater mono amp will do fine. Might want to put a in line fuse holder and start with a 1/4 amp fast blow fuse until you get the hang of how much power you can throw at the head.
Mark
Re: Bypassing the amp on a K-8
Sounds good! What about the motor and switches? Could I run those off just the transformer or would I need a new 80 rectifier? (all the tubes are smashed)markrob wrote: ↑Fri Oct 21, 2022 10:24 amHi,
Just connect right to the wires going to the cutter head. No need to get into the K8 amp at all. Any 50 watt or greater mono amp will do fine. Might want to put a in line fuse holder and start with a 1/4 amp fast blow fuse until you get the hang of how much power you can throw at the head.
Mark
Re: Bypassing the amp on a K-8
Hi,
Looks to me like the motor runs right off the AC mains. From the schematic, it looks like the amp and motor each have their own power switch and can be run independently.
Mark
Looks to me like the motor runs right off the AC mains. From the schematic, it looks like the amp and motor each have their own power switch and can be run independently.
Mark
Re: Bypassing the amp on a K-8
Sounds good! I just recently ran an unamplified audio source (literally an iPad) into the head and it’s faint of course but sounding really crisp at just .8 volts.
Re: Bypassing the amp on a K-8
Started working on the presto today. After doing some poking around, I’ve confirmed that the motor indeed can be isolated entirely from the amp with just cutting the brown wire. For the longest time was under the impression that the power switch on the control panel runs the motor too but it looks like the knob next to the motor is already the only way to control it.
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Re: Bypassing the amp on a K-8
Ok! cutting the brown wire and then putting shrink wrap on seems to have done the trick. I got a platter!
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Re: Bypassing the amp on a K-8
Finally managed to test everything out, was just waiting on an amplifier. CD’s work well, aside from the pitch being a bit off.
Now comes the learning curve I suppose.
Now comes the learning curve I suppose.
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