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PostPosted: Sun Aug 05, 2007 1:13 pm 
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Klaus wrote:
Jocko Homo wrote:
Wouldn't it be easier to use an amp that has differential inputs????

Like a Hypex Class D.

I'm positive it is also a much better amp than anything made with Tripath.

Jocko


The little charlize Tripath amp that I have modded sounds every bit as good as my SKA GB150 and that sounds
better than the Accuphase E 303 I had and better than my AKSA 55 N.
Shinobivan on the other forum compared quite a few amps and he liked the SKA better than the UCD.
One big reason that I use the little Tripath amps is that I can use a 12V Battery or two for 24V as PS.
This makes them highly portable and cheap (because I also use my own boards).
If there is one thing that I learned in HiFi, it is not to advocate a certain technology.
I thought I would never use anything else than Tube amps, but the SKA came so close to my SE 84L amp
that it is only a matter of mood to chose one or the other.
The same goes for dacs. With the purchase of a DDDac I tought non OS is the only way to listen to music,
but then I tweaked (passive out and Rubycon ZL caps) a soundcard with the AK 4396 on it and it walks
all over the DDDac and all my other tweaked players, in all aspects. A few years ago I never ever thought I would use a computer to listen
to musik, but I do now. :D

Greets,
Klaus


Hi Klaus,

HI-FI aside if there is one thing in electronics it is that superior technologies emerge, but the implementation of them still makes a difference.

UCD and a tripath is like a ferrari Vs a moped.

Anyway UCD has true differential inputs as stated and I use mine driven balanced off my soundcard with DC coupling front to back, there isn't an electrolytic or a transformer in the entire mix, speakers are of 102dB sensitivity and I don't hear squat when idle from where I sit. Only a very minor HF hiss can be heard in the very dead of night when all is off, and thats' emanating from common mode noise gone differential mode via imbalances in components and cables. A transformer would help this, as would other things, but it's good enough already. The amps themselves are 100% dead silent on their own. The newer versions also require "zero" tweaking!

A transformer is non ideal as well, but far more so ideal than any coupling cap. You really do need differential one way or the other.


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PostPosted: Sun Aug 05, 2007 4:27 pm 
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Benjamin
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".......Does not seem to be the better option to me."

Why? Because it costs more? A lot more?

Maybe you should try it before you condem it.

Jocko


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PostPosted: Mon Aug 06, 2007 7:22 pm 
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Jocko,

maybe I used the wrong English expression.
Let's say I don't know if Transformers are good
or not because I never tried them.

Ok I will try to use my limited logic on the subject of differential and
you have to straighten me out where I am wrong in the following assumptions.

In data sheet of the TA2020 EB it states that:

"Output Connection
There are four banana connectors on the evaluation board for speaker output. The TA2020-020
has differential outputs, and so it requires two wires per channel to connect to each speaker."

It seems to me that from the ground input the TA chip makes a negative diff. signal for each channel.
Now if I take one amp for the left side and put the negative signal of the left side of the dac
to the ground input of that amp and the positive to the left signal input, do I have one fully diff. channel now ?

Greets,
Klaus


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PostPosted: Mon Aug 06, 2007 8:30 pm 
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Cow
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Quote:
It seems to me that from the ground input the TA chip makes a negative diff. signal for each channel.
Now if I take one amp for the left side and put the negative signal of the left side of the dac
to the ground input of that amp and the positive to the left signal input, do I have one fully diff. channel now ?


How you will combine TWO BRIDGE outputs of TA2020? You can do this with SE output amps e.g. TA2022


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PostPosted: Wed Aug 08, 2007 10:55 pm 
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Sheep

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If you want a differential input without coupling caps, add an instrumentation amp powered by a split rail supply in front of the Tripath amp. With the split rail supply you can DC couple the DAC outputs to the inamp's inputs. Connect the inamp output directly to an input and connect the reference point to the 2.5V bias pin on the chip. Viola, differential to single ended conversion without coupling caps.

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PostPosted: Thu Aug 09, 2007 8:00 am 
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Cow

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Thanks Brian,

I will try this and see if it has any sonic benefit over a good coupling cap.

Klaus


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PostPosted: Thu Aug 09, 2007 7:32 pm 
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Sheep

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BWRX wrote:
Connect the inamp output directly to an input


Don't connect it directly to the op amp input of the Tripath chip. What I meant to say was, connect it directly to the input resistor (no caps). It would be even better if you could buffer the 2.5V bias from the Tripath chip with an opamp too (since you'll have split rails available anyway), but it may not be necessary.

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