Jump to content

St-70


Ramair428cjxr7

Recommended Posts

Hello newbie here , just picked up a st-70 ,was stored with a full set of NOS tubes that came with it . It was tested and ran by son of original owner and builder before I got it ,I've bought a plug that brings my house voltage down to 117 or what it needs to be , removable bias plugs .I plan on running it through a marantz 2222b with a bang tt do u fine people see any problems with that ? All I got rite now is cerwin Vegas 12s 

Link to comment
Share on other sites

It came  with 6 sprauge orange drops and a silicone diode terminal strip for selenium rectifier or something do those pieces go onto the board that can be upgraded for better performance or is that something else ? Is that recommend ? It also came with NOS big bottle 6cac and gz34 tubes  so if I upgrade board do I still use them ? Thanks in advance and sorry for any cornfusion 

Link to comment
Share on other sites

9 hours ago, Ramair428cjxr7 said:

It came  with 6 sprauge orange drops and a silicone diode terminal strip for selenium rectifier or something do those pieces go onto the board that can be upgraded for better performance or is that something else ? Is that recommend ? It also came with NOS big bottle 6cac and gz34 tubes  so if I upgrade board do I still use them ? Thanks in advance and sorry for any cornfusion 

 I would take the amp to a local tech to get your questions answered and make sure it is ready to be a daily user.

Link to comment
Share on other sites

I got one that was rebuilt and works great. Get it checked out or refreshed by a tech to be on safe side. I dont think you need to worry about the house voltage but one of these would be good idea....https://www.amazon.com/gp/product/B0002YDZWO/ref=ox_sc_saved_title_7?smid=A284PRV19Y1MTF&psc=1

I got mine using a 1970s hk 630 reciever as pre amp. works fine running LaScalas.

Link to comment
Share on other sites

Replacing the selenium rectifier with the diode is a good thing, as the old rectifiers will fail. Your onboard DC voltage will be higher with the diode so bringing the line voltage down is good. BUT... take is to someone who knows tube equipment and at the very least, have them go through and check everything.

 

I live where we have TVA power and 125 volts line voltage... my ST-70 power tranny ran hot all the time. When I did a rebuild, I replaced the power transformer with one from Triode Electronics. It still runs warm but not quite like the old one.

 

Bruce

Link to comment
Share on other sites

If those are true old stock 6ca7's then they should be Sylvania's (possibly rebranded RCA's).  I would save those as they're worth some money and replace with some JJ el34's that have been matched (you need matched pairs per side or a matched  quad).  Take the advice here and have it looked over eventually/soon.  Also, the 7199 driver tubes tend to last a long time so if you need new ones find some that have been thoroughly tested.  I tried the 6u8 and the 6gh8 with the adapters and didn't care for the way it sounded. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...