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The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


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    Volume, Tone Controls, and Input Switching

    tomlang
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    tomlang


    Posts : 36
    Join date : 2009-08-12
    • Post n°1

    Volume, Tone Controls, and Input Switching Empty Volume, Tone Controls, and Input Switching

    Post by tomlang Wed Aug 12, 2009 11:52 pm

    A preamp is not really needed to drive a ST-70, correct? If one does not need phono all that really is needed is a "signal conditioner" of unity gain that has volume, tone, and input source switching. What is recommended?

    I suppose if I routed all my audio media through my laptop I could use it but that will not normally be the case.
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    Bob Latino
    Bob Latino
    Bob Latino
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    Posts : 3276
    Join date : 2008-11-26
    Location : Massachusetts
    • Post n°2

    Volume, Tone Controls, and Input Switching Empty Re: Volume, Tone Controls, and Input Switching

    Post by Bob Latino Thu Aug 13, 2009 6:04 am

    tomlang wrote:A preamp is not really needed to drive a ST-70, correct? If one does not need phono all that really is needed is a "signal conditioner" of unity gain that has volume, tone, and input source switching. What is recommended?

    I suppose if I routed all my audio media through my laptop I could use it but that will not normally be the case.

    Hi Tom,

    True, a preamp is not really needed to drive an ST-70. The only thing you really need is a signal source with a volume control. If you have just one input you could use your laptop as a signal source but you could also use an Ipod or a portable CD player - really anything with a volume control. Most of those signal sources mentioned in the previous sentance will have a female stereo miniplug output. Just go to Radio Shack (They are in the process, by the way, of changing their name to "The Shack") and get an interconnect cable that has a male stereo miniplug on one end and dual RCA male plugs on the other end. Plug the miniplug into the laptop, Ipod or portable CD player and the RCA connectors into the ST-70 and use the volume control on the laptop, Ipod Etc. to control the volume on the ST-70. There are also some CD players out there that have a volume control. You could use one of those also. You could also install a volume control on the input of the ST-70 and use it to regulate the input voltage from your CD player etc. The easiest thing to do is remove the near useless stereo/mono switch on the front and wire in a stereo (dual channel) volume control or stepped attenuator to the incoming signal.

    That said, if you have two or more signal sources, you should probably get a preamp to use with your ST-70.

    Bob


    Last edited by Bob Latino on Sun Apr 29, 2012 8:41 pm; edited 1 time in total
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    tomlang
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    tomlang


    Posts : 36
    Join date : 2009-08-12
    • Post n°3

    Volume, Tone Controls, and Input Switching Empty Re: Volume, Tone Controls, and Input Switching

    Post by tomlang Tue Nov 17, 2009 4:47 pm

    I found, for me, the "perfect" solution. After looking at what it would cost to build something, I finally found this and for $80 shipped a real bargain, in my opinion. I have not tested the phono input as I do not have a turntable but it sounds great and the tone controls, bass, mid, treble work very well.

    http://www.jr.com/gemini/pe/GMI_PA7000/
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    atwageman
    atwageman
    atwageman


    Posts : 4
    Join date : 2009-11-08
    Location : North Carolina
    • Post n°4

    Volume, Tone Controls, and Input Switching Empty Re: Volume, Tone Controls, and Input Switching

    Post by atwageman Tue Nov 17, 2009 5:04 pm

    tomlang wrote:I found, for me, the "perfect" solution. After looking at what it would cost to build something, I finally found this and for $80 shipped a real bargain, in my opinion. I have not tested the phono input as I do not have a turntable but it sounds great and the tone controls, bass, mid, treble work very well.

    http://www.jr.com/gemini/pe/GMI_PA7000/

    Not a bad price at all. I'm gonna order one of those myself.
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    Guest
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    • Post n°5

    Volume, Tone Controls, and Input Switching Empty Re: Volume, Tone Controls, and Input Switching

    Post by Guest Sun Apr 29, 2012 3:52 pm

    Bob Latino wrote:
    tomlang wrote:A preamp is not really needed to drive a ST-70, correct? If one does not need phono all that really is needed is a "signal conditioner" of unity gain that has volume, tone, and input source switching. What is recommended?

    I suppose if I routed all my audio media through my laptop I could use it but that will not normally be the case.

    Hi Tom,

    True, a preamp is not really needed to drive an St-70. The only thing you really need is a signal source with a volume control. If you have just one input you could use your laptop as a signal source but you could also use an Ipod or a portable CD player - really anything with a volume control. Most of those signal sources mentioned in the previous sentance will have a female stereo miniplug output. Just go to Radio Shack (They are in the process, by the way, of changing their name to "The Shack") and get an interconnect cable that has a male stereo miniplug on one end and dual RCA male plugs on the other end. Plug the miniplug into the laptop, Ipod or portable CD player and the RCA connectors into the ST-70 and use the volume control on the laptop, Ipod Etc. to control the volume on the ST-70. There are also some CD players out there that have a volume control. You could use one of those also. You could also install a volume control on the input of the ST-70 and use it to regulate the input voltage from your CD player etc. The easiest thing to do is remove the near useless stero/mono switch on the front and wire in a stereo (dual channel) volume control or stepped attenuator to the incoming signal.

    That said, if you have two or more signal sources, you should probably get a preamp to use with your ST-70.

    Bob

    I have wondered about my old portable CD player's volume control. I always thought it just worked for controlling the volume for the headphones. It does have a female mini-plug output which I guess I can plug into my ST-35 and use the volume control to control SPL's? Output voltage is 0.6V for the CD player.
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    • Post n°6

    Volume, Tone Controls, and Input Switching Empty Re: Volume, Tone Controls, and Input Switching

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