spritzer
Member of the Trade: Mjölnir Audio
- Joined
- Aug 22, 2002
- Posts
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A Stax amp will always have to be balanced at the output regardless of the input so it makes sense to have a balanced input as well. It's almost always cheaper to design an amp with a "free" balanced input (i.e. enough open loop gain to do it's own phase splitting) instead of using a singled ended input and feed that into a phase splitter. Less parts and if one only wants to use RCA then it's a simple matter of grounding the - input. This naturally halves the ultimate voltage swing (as you are only feeding it half the input voltage of a balanced signal, 2.1Vrms vs. 4.2Vrms) but that's the only negative effect.
The real problem with solid state is that once the parts are out of production, they are gone forever or go for silly prices. This is especially true for high voltage parts and these are disappearing quickly. With tubes we don't have this problem, it's a niche market so manufacturers are happy to sell less units and there is a large infrastructure out there to sell matched tubes to hobbyists. We will also only use current production tubes and only triodes at that. Tubes are also very forgiving to mistakes and many will take a lot of abuse before giving up the ghost. With sand this isn't the case and they have a ca. 20% safety margin and after that they release the magic smoke.
One problem with a simple tube amp is optimizing performance without spending too much. While a two stage amp might work it really has to have three stages (i.e. 3 triodes per phase so six dual triodes per amp) and there is really no way of doing this DC coupled. That means at least one capacitor in the signal path but I can live with that and perhaps spend more money optimizing the operating point for the tubes to drag it into the 21st century.
Quote:
I would never release anything as bad as the Exstata so yeah, it will be better and the price will be similar. With an amp like this we have to use custom made transformers but that shouldn't add to the cost at all and it beats those crappy Hammond 270 cores. With both driver and output tubes in use we can't have them share the same filament tap and I can't find any off the shelf transformer which fits that general description.
The real problem with solid state is that once the parts are out of production, they are gone forever or go for silly prices. This is especially true for high voltage parts and these are disappearing quickly. With tubes we don't have this problem, it's a niche market so manufacturers are happy to sell less units and there is a large infrastructure out there to sell matched tubes to hobbyists. We will also only use current production tubes and only triodes at that. Tubes are also very forgiving to mistakes and many will take a lot of abuse before giving up the ghost. With sand this isn't the case and they have a ca. 20% safety margin and after that they release the magic smoke.
One problem with a simple tube amp is optimizing performance without spending too much. While a two stage amp might work it really has to have three stages (i.e. 3 triodes per phase so six dual triodes per amp) and there is really no way of doing this DC coupled. That means at least one capacitor in the signal path but I can live with that and perhaps spend more money optimizing the operating point for the tubes to drag it into the 21st century.
Quote:
I would never release anything as bad as the Exstata so yeah, it will be better and the price will be similar. With an amp like this we have to use custom made transformers but that shouldn't add to the cost at all and it beats those crappy Hammond 270 cores. With both driver and output tubes in use we can't have them share the same filament tap and I can't find any off the shelf transformer which fits that general description.
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