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In the Forum: Audio Discussions
In the Thread: All Active! A DSET and multi-way acoustic system.
Post Subject: Transient effect and DSETsPosted by Romy the Cat on: 4/30/2011
Here is another advantage of multisampling and DSET in particularly. There are many moments in amp that in one or another degree affects transients.

The capacitive coupling for instance works fine but as long the amp sits in class A1. As soon amp hit the A2 all hell breaks loose for transients. Some people built “expensive” SETs. This makes me laugh. Let take for instance Lamm ML3. Lamm uses DHT tube that can work well in A2. In addition ML2 has huge second stage buffer (8 anodes) to drive the output stage grid currents. Looks like “expensive” design, does it? Well, ML3 use capacitance coupling –it works is fine as lone the capacitor is biased. What from one side is DC then the dialectic is polarized and the AC is floating fine. However, then 32W Lamm ML3 begin to drive those funny powered woofers of those Wilsons and woofer’s impedance drops then ML3 dive might hit A2. There is nothing wrong for THIS amp to work in A2, the GM70 can do it and the driver can provide sufficient current, but at the very time when amp enter A2 the coupling caps begin to change AC polarity and dielectric begin to recharge. This is not good Sound generally and it is VERY bad for HF. So, at the time when this type of amp have the LF stress, even all supplies can supply everything fine but the upper-range of the amp become transiently compromised due to the re-polarization of capacitors.

The transformer coupling is not much better. Transformer has inductance and act as choke in a way Try to measure current from a PS choke and turn the supply down. The current will be still flowing from the choke AFTER the supply is down. The choke will be storing energy and try to act like a gyroscope, maintaining the cruse current. Now pretend that the same thing sits between as a coupling devise between the stages…

I do not draw the pictures of misery about amp, I juts saying that in multisampling this effect would not exes tans you in multisampling will be able to select for any given channel the preferred coupling options. It is not to mention that any multisamp (DSET) works in a limited frequency range where all signals are of the same similar type, thus the optimization is very much possible.

The Cat

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