Class D is just Dandy!

ricred,

There is a pair on audiogon,if you didn't see them.

Kenny.

Look at at Questyle and Exogal... not the magical 5.8-9 yet but sure getting people to say that cost vs performance is ohhh so c...lose.

Ralph, it appears to me that what underlies much of the disagreement between you and Erik is that he is viewing the impedance of an output coupling capacitor, if present, as contributing to and being part of the component’s output impedance. While you are not, possibly because you are considering "output impedance" as corresponding to "specified output impedance," which as we all agree is often based on a mid-range frequency such as 1 kHz. The capacitor’s impedance of course being unlikely to be a major contributor to the 1 kHz output impedance in just about any reasonable design.

Thanks Al! To be clear here, this was Off topic (we're working on our own class D circuit that is not based on any modules so you can draw your own conclusion about what my attitude about class D is); my main concern was was to try to express the idea that it was the output coupling cap in a given design that was determining the frequency response variation seen in some designs. Since there are tube preamps with a high output impedance that also do not have the rising impedance as seen (due to the fact that they have larger coupling caps), its hard to allow a generalization like 'high output impedance leads to frequency response errors' or the like. It doesn't have to was my point and I didn't have to look very far to find examples.

Put another way, its the rising impedance at low frequency, not the **overall** higher output impedance that causes the problem; I should have expressed it that way earlier!

Ralph,

When do you think you will have your class d ready to sale.

Can you give us any details about it.


Kenny.