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Preamp to use with Dynaco ST-70?

Magnolia Tom

Magnolia Tom

Active Member
I just made an impulse buy of an ST-70 and should be getting it delivered next week. I bought it because of all the reviews praising the mid range and how the music has a 3D (holographic) quality. I’ll mainly be listening to Jazz. My question is on a preamp.

I planned on using my pioneer sx-838 as the preamp. Speakers are some Klipsch floor standing with 96dB efficiency. I will be playing vinyl mostly. Will this setup work well? Or should I look into getting a tube preamp?

I’m a complete novice on tubes, tube amps, etc so any guidance would be greatly appreciated.

Btw, pictures are coming once I receive the amp. I had a saying on RV forums….”Pics or it didn’t happen”.lol. Not sure if that’s a thing here but I’ll be sure to post some when I get it.
 
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Many will say use a tube preamplifier with it. I prefer to use a SS one with my tube amplifiers. I like NAD for a no frills inexpensive preamp. Use a Denon the most but will switch out a Audio Research. End going back to the Denon.
 
Here are some pictures from the listing
 

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The Klipsch should sound nice with the Dynaco. I'm using JBL L-100's on my Dynaco MK IV's right now.

Those Mullards are great tubes in a Dynaco.

If it has the 7199's get some adapters to go to 6U8's and save them. They are very expensive tubes.....
 
Oerets said:
The Klipsch should sound nice with the Dynaco. I'm using JBL L-100's on my Dynaco MK IV's right now.

Those Mullards are great tubes in a Dynaco.
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I’m debating on switching up my living room setup so I can use pioneer HPM100 but I have a quad receiver in the LR and using it as a preamp isn’t really possible that I’m aware of
 
The ST-70 appears to be in very nice condition. The Pioneer should work pretty well for this purpose if all the controls and switches are in good condition. You will probably want to try a more minimalist approach sooner or later, preferably with tubes.

Jack
 
TriodeLuvr said:
The ST-70 appears to be in very nice condition. The Pioneer should work pretty well for this purpose if all the controls and switches are in good condition. You will probably want to try a more minimalist approach sooner or later, preferably with tubes.

Jack
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Yes the Pioneer is in good shape and has been serviced in the past year. I kinda already am getting the feeling of tube preamps in my future. Possibly some Klipsch Heresy’s as well. Damn this hobby is a never ending struggle! Lol but that’s why we love it I guess.
 
It’s been recapped and some resistors have been replaced. Sadly, the resistors aren’t matching from side to side.
I’ll be interested in your thoughts about how it sounds as I’m in the process of restoring one now.
Here‘s a look at mine after cleaning it up.
5FE498D8-68DC-45A4-B3A0-55A493F5AEE6.jpeg

Good Luck! Mark
 
I'm in the tube preamp camp. I use a 22 year old Transcendent Sound Grounded Grid I built.
If those output tubes and rectifier test good you scored well.
Replace that selenium rectifier with a n4007 diode.
 
TubesGlo said:
I'm in the tube preamp camp. I use a 22 year old Transcendent Sound Grounded Grid I built.
If those output tubes and rectifier test good you scored well.
Replace that selenium rectifier with a n4007 diode.
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That's so weird because I was just thinking about the GG kit that I had built and loved. Always thought about going back and building another from scratch because it was a simple circuit...and sadly misnamed by Bruce as he caught a lot of flak for that. But it was very quiet and very fast...great transient response. I put some 5814's in there and it was amazing with the CJ amp I had at the time. Would highly recommend that circuit for anyone looking for a DIY preamp.
 
the classic pairing is a PAS of course, but anything that can give you a volt and a half of output will do the job. These aren't a difficult load for a preamp, and they don't need vast input voltage either. Pretty sure I've done zero to narrow this down :)

Personally I'm not over the moon with preamps that just have a lot of gain, so I'd probably be going for something thats on the low side. Makes for a less touchy volume knob, and having a ton of gain that gets thrown away in attenuators or whatever is more likely to result in extra noise. Having a decent phono stage will be more important if your main source is a turntable.
 
John Ess said:
That's so weird because I was just thinking about the GG kit that I had built and loved. Always thought about going back and building another from scratch because it was a simple circuit...and sadly misnamed by Bruce as he caught a lot of flak for that. But it was very quiet and very fast...great transient response. I put some 5814's in there and it was amazing with the CJ amp I had at the time. Would highly recommend that circuit for anyone looking for a DIY preamp.
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Yup, very neutral and dead silent passing absolutely no hiss, buzz or hum at idle to the amp. I built a Goldpoint 24 position attenuator with PRP resistors and use film, foil output caps with various NOS 12au7 including Mullard CV4003'S. I have no need for change after all these years, love this simple preamp.
 
if you have the option to sub a 6CG7 for the 12AU7 when building it, consider doing that. They are more linear, but otherwise pretty similar. Slightly different pinout though so its not a drop-in. Should be able to modify a PCB though, the tube connections are the same, but its 6v from pin 4 to 5 and pin 9 is an internal shield. Unless thats on the 6FQ7, which is also electrically the same. One has a shield inside, one does not, and I can never remember which is what. They're both a 9 pin 6SN7 though and can swap for one another with no fuss.
 
I have a tube pre on one system and ss on the other. The tube pre feeds an integrated (barely) el34 amp. The ss goes to el84 monoblocks.

Both options have their strengths which may or may not be a good pair to the power amp you choose/have.

Honestly although I love the all tube chain the ss pre on the ‘secondary’ system gets more of my time. It’s convenient, has a half dozen inputs and direct bypass and a remote. When you are lazy these things matter :)

You can also get a decent used ss integrated with pre out for peanuts and many have a decent phono and or dac. Then bide your time, research, audition and decide on the ‘perfect pre’ for your st-70 (nice score btw)
 
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