RekOKut Imperial II restoration project

[mrd]

Many thanks for this, yes, I'd read your other thread already - super interesting. The 1C I'd been running with a stepup transformer as it's a 500ohm but up until this point It's been a using boat anchor of a power amp so that doesn't help. Some new valves for the R8 arrived today (they were also smashed in transit) so I'm hoping to get this up and running and see how much of a difference that makes. I don't have a feedback amp for the Grampian so I've been just rolling without the feedback winding connected - it definitely sounds better and clearer that the 1C to my ears (regardless of any embossing/cutting()with the same amp.

The weight is there so maybe the spring is deformed but I'm not sure how much this helps if the head is too heavy in the first place and it's wound right back. I'll add a photo tomorrow if I get the chance.

Yeah, I've had the sapphire from Mike, I'm just less keen on importing blanks from further away as I'm UK based (though I guess it might not make that much difference between France and here in due course ) Maybe I should be biting the bullet and using a myshank diamond too?! Or just going for Mike's blanks as you say.

I did end up buying a USB scope and was suprised how close the grooves seemed to be but haven't measured this properly yet. The feedscrew didn't seem crazy LPI so now I'm a bit confused, maybe still too much weight on the head. Maybe worth adding a dashpot? but really unsure of appropriate values.

[mrd]

OK so it's 210 LPI which accounts for the closeness I guess.

Photo of the assembly -


( ignore the brackets this is how I have been adding more weight).

[mrd]

Wow, what a difference a decent amplifier makes! Now getting somewhere with a decent sounding louder cut -some issues with static but I'm still having to counterbalance manually with quite a lot of weight. Does the setup look right?

[Fela Borbone]

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[Fela Borbone]

I had to counterbalance my Rek o Kut too, when hung a 1-C on it...

[mrd]

I had to counterbalance my Rek o Kut too, when hung a 1-C on it...

Thanks Fela, good to know!

[jesusfwrl]

mrd, I wouldn't try any form of jewel stylus until you have figured out what is up with the weight/spring/depth. For embossing and all kinds of metallic stylii, Mike's blanks are great. Worth at least getting a pack of 7" blanks to figure out the settings with. The R8 will most probably run out of juice with the Grampian. Make sure you check valve bias in the R8.

[jesusfwrl]

Yes, a good amplifier is extremely important to get decent results out of any lathe and cutter head.

A couple of notes regarding your setup: The depth spring looks like it is set for a rather deep cut. Why not unscrew the knurled nut a few turns instead of adding weight? The only situation where more weight would be needed is if even with the spring entirely removed, the head would tilt down towards the record surface. Normally, the counterweight alone should keep the head up. The spring is what brings it down. Your top spring looks a bit odd… Not sure if this is an issue though.
With the spring removed, the suspension should freely move by hand, but should return to the head-up position due to the counterweight.

Something I should point out is that, at least with the Audax head and a correctly balanced and adjusted suspension, the Rek-O-Kut Imperial II allowed an impressively accurate control of groove depth, over an unusually wide range, from very shallow to super deep. There was no indication that a dashpot would be needed, even when cutting, so especially for embossing, this is not an issue at all. The suspension is very well designed and is probably the best of the portable lathes when it comes to setting the depth of cut.

[mrd]

Thanks again, I missed the last message. I'll look into bias for the R8 - I've only checked things by eye at this point but nothing seems to be horrendously glowing and it does sound good..

OK, I had been unscrewing the nut so that there is no tension on the spring at all and the counterweight still did not hold the head up. Perhaps it is a top spring issue as you say, maybe that threaded rod is stuck somehow in that middle section if that doesn't look right..I'll have a look tomorrow.

Really good to know about the design of the ROK works well, when it's balanced properly

[mrd]

Ok, an update for those still following, the spring/threaded part was a bit stuck at the top so freeing it up has helped considerably though without any tension on the spring at all I still have to put some weight on to balance the Grampian but nowhere near what I had to do before. Thanks for all the help

[grooveguy]

Yea, progress! Keep us informed, and please post sound clips of your successes.

[mrd]

Thanks Grooveguy! Will do, though maybe I should stop hijacking this awesome thread!

[morrisjer]

If anyone has a manual or especially schematics of a Rek-0-kut Challenger TR 12H I sure would appreciate it!
Thanks!

[markrob]

Hi,

I think the R8 Amp was used on the TR12. I have the A and B version of the schematics. Hope that works for you

R8A.jpg

R8B_Schematic.jpg

[morrisjer]

THANKS so much for the schematics! I will copy and save them.