Dynaco ST-70
Apr 10, 2002 at 2:04 AM Thread Starter Post #1 of 15

TimSchirmer

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I recently took a trip to Audio Concepts in Long Beach, CA and noticed that a dynaco ST-70 tube amp had a headphone jack. Sadly, I did not have my senn's to test them out on the amp. Anyone ever tried vintage tube amps with headphone jacks?
 
Apr 11, 2002 at 4:09 AM Post #2 of 15

TimSchirmer

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hmmmm...found another on ebay...with a headphone jack...here is the pic
st70-2.jpg
 
Apr 11, 2002 at 5:26 AM Post #4 of 15
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are you sure that's a headphone out? i owned one of those amps in the late 50s, and i thought that was a connection to the preamp. i may be wrong, but i'd check before sticking 'phones in, at least with them over my ears. now, thinking of it, i'm really not sure.
 
Apr 11, 2002 at 5:46 AM Post #6 of 15

TimSchirmer

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that thing is modded to be a headamp. I don't wanna blow three hundred bucks on something i don't know about though.
 
Apr 11, 2002 at 5:55 AM Post #7 of 15

KurtW

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Many Dynaco amps have been modified for a headphone output, but this was not a factory option. Because of this, you would have to look to see how this was done, but I would guess that most of these were done by adding a 100 or 200 ohm resistor in series with the output, similar to what is done with other amps with headphone outputs. This is a reasonable way to add a headphone output to an amp designed to drive speakers. Strictly for headphones, you are probably better sticking with low power amps since you don't need the power for headphones. Low power amps can sound better than higher power amps, but if you need the power for your speakers you have no choice but to make compromises in order to get the power you need.
 
Apr 12, 2002 at 4:57 PM Post #10 of 15

KurtW

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The volume is controlled by the preamp that you would use with this amp. I've also seen Dynaco's integrated amp (combo amp and preamp), the SCA-35, with an added headphone jack. I have one of these amps and has a hole drilled out for one, so I'll have to stick in a jack and see how it sounds. I use it now with a old Stax electret headphone which requires to be hooked up to speaker outputs, and it sounds pretty nice.
 
Apr 13, 2002 at 2:23 AM Post #12 of 15

Mr. Thompson

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The 1/4 phone jack and the two toggle switchs are mods. Neither comes standard on the ST-70.

A properly setup ST-70 can be entirely engaging to listen to. I remember loaning my tweaked out ST-70 to one of the folks from Holmes Powell in the mid 80s. While it was not very powerfull, my friend still claims that ST-70 was the most musical tube amp he has experienced.

If you have the time and the skills, a pair of ST-70s can be put into decent conditon to do a fine job bi-amping a pair of speakers. Well worth keeping an eye out for at garage sales.
 
Apr 13, 2002 at 4:58 PM Post #13 of 15

TimSchirmer

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I tried the dynaco with some HD600's. The combo sounded great! Very warm....I really want to pick up one of those ST35's that kurt mentioned though.
 
Apr 13, 2002 at 5:00 PM Post #14 of 15

TimSchirmer

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then again...the store had a seperate preamp hooked up. I think the 35 would be a good choice since it is integrated.
 
Apr 8, 2016 at 8:25 AM Post #15 of 15

buson160man

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The volume is controlled by the preamp that you would use with this amp. I've also seen Dynaco's integrated amp (combo amp and preamp), the SCA-35, with an added headphone jack. I have one of these amps and has a hole drilled out for one, so I'll have to stick in a jack and see how it sounds. I use it now with a old Stax electret headphone which requires to be hooked up to speaker outputs, and it sounds pretty nice.


 I used to have a tweaked modernized SCA-35 myself . The unit was a blast . I use to call it my pocket battleship . I loved to take it over to peoples houses and watch the peoples reaction when it just blew away their receivers for sound quality . Unfortunately I borrowed it to someone that I had met in college at night school and when I tried to get it back they had moved and stolen the amp from me .
 

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