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    Question for Bob

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    hfh

    Posts : 2
    Join date : 2009-12-18

    Question for Bob

    Post by hfh on Sun Apr 11, 2010 4:04 pm

    I built your ST70 kit in August '09 with cap upgrades and love it !! I'm using a McIntosh C28 pre-amp. Everything was great until the volume control went bad on the C28. I sent it to Terry Dewick (well known McIntosh specialist) to replace it. Unfortunately the only control now available with a power switch isn't the electrical equivelant to the original. So now when set to minimum volume it plays too loud for night listening. I have the top panel main output pots set at minimum. I really don't want to change the ST70 board to the low gain version because it works fine with other pre-amps I have used (and I already changed the 12AT7's to the Valve Electronics Mullards). I know you advised changing the center tube to a 12AU7 in this forum but I would rather leave the ST70 alone if possible as there is nothing wrong with it. I've been advised to try inline RCA attenuators between the pre-amp and power amp. I know there are variable and fixed value ones made. Would you recommend this and if so any spacific ones you like ? Thanks, Chuck

    Bob Latino
    Admin

    Posts : 2411
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Question for Bob

    Post by Bob Latino on Sun Apr 11, 2010 5:40 pm

    hfh wrote:I built your ST70 kit in August '09 with cap upgrades and love it !! I'm using a McIntosh C28 pre-amp. Everything was great until the volume control went bad on the C28. I sent it to Terry Dewick (well known McIntosh specialist) to replace it. Unfortunately the only control now available with a power switch isn't the electrical equivelant to the original. So now when set to minimum volume it plays too loud for night listening. I have the top panel main output pots set at minimum. I really don't want to change the ST70 board to the low gain version because it works fine with other pre-amps I have used (and I already changed the 12AT7's to the Valve Electronics Mullards). I know you advised changing the center tube to a 12AU7 in this forum but I would rather leave the ST70 alone if possible as there is nothing wrong with it. I've been advised to try inline RCA attenuators between the pre-amp and power amp. I know there are variable and fixed value ones made. Would you recommend this and if so any spacific ones you like ? Thanks, Chuck

    Hi Chuck,

    I have heard of a few people using RCA inline attenuators in cases where their preamp is set up to have the volume come on too quickly. On the VTA ST-70 and ST-120 you would probably be better off placing the attenuators on the back of the preamp because the ST-70's input jacks are fairly close together. Parts Express sells a number of RCA attenuators at the link below. Probably either a 3 dB or 6 dB attenuator would work best in your situation.

    Parts Express RCA attenuators

    Bob

    hfh

    Posts : 2
    Join date : 2009-12-18

    Re: Question for Bob

    Post by hfh on Mon Apr 12, 2010 1:47 pm

    Thanks Bob, Just ordered a pair of Harrison Labs 6db attenuators. Chuck

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