200S multi cap can replacement

[Greg_M]

Making your own amp is admirable, though it will be more expensive than purchasing one used. If you've never made an amp before, then you could run into troubleshooing issues once it is built to eliminate hum, oscillations, etc. That said, it is a fun hobby and can be very rewarding. Good luck on whatever you decide to do with it.

Greg

If you build one from new parts you have a new vintage amp. If you buy one used you have a 40 year old amp with 40 year of components. Yes it may cost more but you wind up with a new item instead of a beat up, used up item.

I have had several tube amps from the 60s (when they were cheap) until now. I played bass back then through Dynaco Mk IIIs which is what the Sunn 200S is made from. I currently have a McIntosh MC275 which replaced a pair of Dynakit Stereo 70s. I still have one of the Dynakits and monkey and fiddle with it still.  I have always had to fix and make my own stuff, so I essentially have had 40+ years of "education"
Thanks


I forgot the most important part, it's fun.

[doc10039]

Does anyone have a layout to build the power caps using sprague atoms?


Doc

[EdBass]

Does anyone have a layout to build the power caps using sprague atoms?

I don't think there is one, and using the big Spragues would be a challenge in a 200S chassis and probably not the best option anyway, Soundmasterg covers it pretty well in his post in this thread.
Plus, I don't think Sprague even makes a 30uF above 500 VDC.
This thread covers a variety of good options if you read it through, and there have been several threads on the subject if you use the search function.

[doc10039]

I am thinking of using a tag board similar to a fender design. Mount them on top of the chassis or under after the cap can is removed. I have found some solen caps that are rated for 600 plus vdc from AES.

[doc10039]

In my last reply I said I found some solen caps to replace the multi cap. These caps are not polarized. Probably will be using either F/T caps or a JJ multi cap.


Doc

[Soundmasterg]

Solen are polypropylene and will outlast you, and would work very well. however they are HUGE.....there is no way you would be able to fit them in a 200S. I have some that I am going to use for a 2000S rebuild, but there is a lot more room in that chassis for them so it will work ok in that application. Basically a Solen 630v 22uf cap is about 5 times the size of an equvilant electrolytic so you'll have to use electrolytics in your application. There are several ways to go on this, and I've posted about some of them in the past if you search, and I've posted also on this thread too. If you use terminal strips and some careful layout, you can make it work well with a minimum of drilling holes to mount the terminal strips. I do not recommend to wire it up the way Fender does. They did it that way for ease of production and service, but there is no performance reason for that, and in fact, wiring the caps all up in a doghouse on a board is not the best way to do it. Not only do you cut a big hole in the chassis to mount a board like that, but ideally, the caps should be located as close to the circuits they supply as possible, with all the grounds for that circuit going to the negative end of the cap. In the Sunns that is impractical without changing some other wiring in the amp, but it can be done. i've done this to my 200S and I isolated all the grounds except for at one point to the chassis, and it is a very quiet amp now with little to no hum.

Another good and quick/easy option are the SDS cap boards, which should go right into your 200S. EdBass among others has posted pictures of this option and it is an easier approach than the way I have recommended in the past.

Greg

[CLD]

I just got my 200S back with the SDS board in it to replace the old caps. Can't tell you about the longevity yet, obviously, but it certainly sounds great! (The board was mounted on the bottom of the chassis, where there is more room and it is out of sight.)