DACT vs Joshua Tree Attenuator??

[DoYouRight]

I understand DACT are known to be excellent, I have a 24 step balanced one. However after glancing at the Joshua Tree and its 128 steps? Are you serious, the quality might look less than but still is it noticeable?

I am fighting over gain on my bal B22. I am thinking of putting an input attenuator so that I can have 5 gain for both SE and BAL (2.5x2) and am curious if the Joshua Tree will really give me more control with less hassle? But I absolutely don't want more noise, etc. Thanks

 

[FallenAngel]

Do you feel that the DACT does not give you enough usable control range that you need more steps?

 

[DoYouRight]

I still havent cased everything up completely, as I am curious about the LCD1 Arduino, and some other random things.

However, my Gain is at 5 (BAL 10) and I feel when I get cans like hd800 it might be too much since the default is 4 that most like from buffalo32. So a Input attenuator is probably gonna be necessary. For the DACT I am ok with it now, but if I want more finetuning later wouldnt it be a huge hassle to redo it? The JT looks very cool and has 5x the steps. Just curious if it could help with gain from varying headphones.

 

[n_maher]

I personally have not used the JT because of the lack of a mute or zero volume setting. At max it is attenuating the signal by -63.5db which in my experience is very audible. I like to be able to turn the volume all the way down.

 

[DoYouRight]

i thought the new one had mute according to the site.

 

[Steve Eddy]

What value DACT do you have?

If you're just looking to knock off 6dB of gain so you can have the same gain with unbalanced phones as with balanced phones, you can simply wire series resistors just ahead of the DACT of the same value as the end to end resistance of the DACT. That will knock off 6dB of gain for using balanced phones, and use a switch to short across the resistors for unbalanced phones.

Another option would be to set the gain of each channel to 2.5, and then add a pair of output transformers. You can take your balanced output straight off the transformer primaries, and then wire up the secondaries for a TRS (commoning the bottom of each secondary) for use with unbalanced phones. That would give you approximately the same gain for both balanced and unbalanced.

The "penalty" would be a bit higher output impedance for the unbalanced output due to the transformers' winding resistance.

se

 

[mugdecoffee]

Quote:

Originally Posted by n_maher /img/forum/go_quote.gif I personally have not used the JT because of the lack of a mute or zero volume setting. At max it is attenuating the signal by -63.5db which in my experience is very audible. I like to be able to turn the volume all the way down.

Couldn't you fix this by just not populating a resistor?

 

[Beefy]

Quote:

Originally Posted by n_maher /img/forum/go_quote.gif I personally have not used the JT because of the lack of a mute or zero volume setting. At max it is attenuating the signal by -63.5db which in my experience is very audible. I like to be able to turn the volume all the way down.

New version has mute

"The kit uses Vishay/Dale 1% CMF resistors, providing 0dB to -63.5dB of attenutation (+ mute) in .5dB steps."

 

[n_maher]

That's good, I recently had the chance to use one of their older models on an amp I was fixing for a friend and it was pretty annoying and freaked me out the first time I got it back together and running. I also found that it made it impossible to use the amp with some headphones depending on the source I was feeding the amp with. FWIW this was a balanced beta22 with an effective gain of 10 (5 x 2) fed by my DAC which has a standard 4V balanced output (I'd have to double check that).

 

[DoYouRight]

would you think a JT would be better for Grados/Denons ? I am debating just snagging one and comparing but Im throwing away money like crazy lately.

 

[IPodPJ]

I'm pretty sure I'm going with a DACT CT2-4 50kOhm for mine. I would love to have remote control though, still undecided. Anyone know of any remote control motor drive systems that I could use with it?

Nevermind, I found it. From Bent Audio, specifically made for DACT. $190 (+$10 for optional power supply, but I'd probably go with a Twisted Pear for that.)
http://www.bentaudio.com/index2.html

 

[Steve Eddy]

Quote:

Originally Posted by IPodPJ /img/forum/go_quote.gif I'm pretty sure I'm going with a DACT CT2-4 50kOhm for mine.

Make that 25k. My bad. I was thinking single ended when I said 50k.

se

 

[Beefy]

Why would you need to drop it to 25kohm for balanced?

 

[n_maher]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif Why would you need to drop it to 25kohm for balanced?

There's no need, but lower is always theoretically better from a noise standpoint. If you know what your source is going to be and that you won't be changing it any time soon you could go lower to 10k.

 

[Steve Eddy]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif Why would you need to drop it to 25kohm for balanced?

Because the target is a 50k input impedance.

se