Rickresource Rickenbacker Forum

Hi Charles. I was wondering if you can recommend any good mods to do to restore/upgrade a Dynaco Stereo 70? I got one a couple years ago for free, and it came with a good Amperex GZ34 thats now in my AC30, and it also came with 4 good Mullard EL34's. I've seen lots of mods around on the net, including the ones at Triode Electronics, and was thinking of going with the two EF86/12AU7 board, and also with the power supply board that Ned/SDS Labs sell. I'd have to get them to custom make me the EF86 board though, as they stopped making it due to poor EF86 supply.

All of the mods from Triode, and others, seem to use better tube types than the 7199's, upgrade to a modern board, and upgrade to higher filter values to stiffen things up for the most part. Its hard to know which way to go without being able to hear one first. I'm sure with your experience that you've probably heard some of the different boards out there and could comment on them?

I need to restore the chassis too and get rid of rust, without ruining the lettering. And I'll need speakers...and have no idea what is good. Thanks!

The Triode Elec. ST 70 board is very good. It normally uses 6GH8s or 6U8s I believe. The supply of newly made EF86s is poor. Only Sovtek has anything and it generally sucks. I understand that JJ is coming out with a new reissue EF86 sometime soon.

The stock board is good with the standard configuration of tubes.

As far as rust on the chassis. It depends on if it is just scale rust or pitted rust. If it is light scale, you can use two products:

1. TR3 available in automotive stores. It is a fine rubbing compound mixed in with wax. It can be carefully applied with very soft rags to rub the rust out.

2. Simichrome is a German product used as a metal polish, it can also be used, but is a bit more abrasive and may leave some scratch marks if you are not careful.

Be careful when applying these products around the lettering. The lettering is just screened on the chassis and is not baked on, it will come off if you are not careful.

Good luck.

Thank you Charles! What about using something like Metal Ready to clean the rust up, and then using a metal polish to shine it up? Metal Ready is used often on car restorations and chemically changes the rust into metal again, or something like that.

I'm more familiar with the EF86 rather than the 6GH8 or 6U8, so that was why I had an interest in that board. They used to make it and then stopped due to the poor supply of EF86's, but Ned at Triode told me that the guy at SDS Labs would make me one if I wanted. He hasn't emailed me back about it yet though.