think i missed what amp it is you are working with .
I have two Classe CA-100 and two Classe CA-150 amps.
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think i missed what amp it is you are working with .
Excellent! Explained very well and thank you! So at the minimum 14mv bias setting the amp is running 100% in class B all the time?
At 24mv (the manufacture’s highest recommended bias) the amp is running at maximum class A possible within the amp’s design and heat sink capability etc?
The only way to successfully match them is to first get them as close as possible with your dvm and then pick either left or right and turn that pot while listening to music, matching it to the other.
I have found that summing the value of all outputs, that is BJTs, to about 150ma per channel is optimum for an AB amp.
I'm not a tech. I would assume that if in a multi-channel amp each channel has it's own outputs/pots, the process would be equally beneficial.Sounds intriguing. Please go over your "matching" process in a bit more detail. What exactly are you adjusting, measuring, and listening to in order to achieve the optimum match? Will this work for multi-channel amps as well as it does for stereo ones?
Whether it's 4 or 10 per channel, the outcome is the same. 150ma total. So the more outputs there are, the less load there is per outputhow many milliamps does that work out for each output transistor ?
sorry i cannot make sense of this .Whether it's 4 or 10 per channel, the outcome is the same. 150ma total. So the more outputs there are, the less load there is per output
As far as I have researched, this follows typical design convention. Increasing the number of outputs serves to share the load, thereby increasing reliability by keeping the outputs cooler at a given power output.sorry i cannot make sense of this .
ok so should the typical 2 transistors npn pnp share the same 150 milliamps as one with say 4 outputs npn pnp in a parallel configuration ?As far as I have researched, this follows typical design convention. Increasing the number of outputs serves to share the load, thereby increasing reliability by keeping the outputs cooler at a given power output.
I'm matching quiescent current with the bias pots. After initial dvm, it's all ears, sitting right between the speakers with the amp.
What I'm listening for is dimensionality. All of a sudden, sound sources are placed in space, seemingly not eminating from either speaker. Hard to describe since the usual descriptors are typically used erroneously. Here is where it really happens, or, in a real sense.
Transients are so clear and pure as to ring like a bell.
I would think so. But I understand not all outputs are rated the same voltage. I have generalized in reference to the amps I've mentioned. Point being that equilibrium is most important.ok so should the typical 2 transistors npn pnp share the same 150 milliamps as one with say 4 outputs npn pnp in a parallel configuration ?
Yes, but increasing quiescent current can be advantageous also. Stereo is much better in finding the sweet spot . As I mentioned, once you're satisfied you've done your best with your dvm in terms of equalizing both channels(just because your dvm tells you it's at spec doesn't mean it actually is. It will fluctuate within a range anyway). So matching is a matter of tuning one channel to the other regardless what direction achieves it.Thanks for the info. Let's see if I've got this right (assume stereo amp with per channel adjustable bias pots):
1. Set bias current (voltage) to manufacturer's spec by adjusting both channel's bias pots to specified current (used hereafter) using DVM.
2. Once idle bias current set, run a (stereo/mono?) music source into the amp and take listening position exactly between the speakers.
3. Adjust bias pot on one channel to produce MORE current (because you don't want to go UNDER the manufacturer's spec, right?) until "dimensionality" and clearness of transients ("ring like a bell") is maximized.
(4. For multichannel amps use same base channel as in Step 3., add a new second channel, and adjust the new channel for max. dim. and c.of t. Repeat Step 4. for all other channels, careful to use same base channel throughout.)
Do I understand your "bias adjustment to ear" procedure correctly?
Yes, but increasing quiescent current can be advantageous also. Stereo is much better in finding the sweet spot . As I mentioned, once you're satisfied you've done your best with your dvm in terms of equalizing both channels(just because your dvm tells you it's at spec doesn't mean it actually is. It will fluctuate within a range anyway). So matching is a matter of tuning one channel to the other regardless what direction achieves it.
Yes of course you are correct. Keeping them within their linear operating "range" is obviously the goal. The problem is they all fluctuate within this range. Listening for optimal settings once they're in there is the most precise way to match their behavior.Your last sentence doesn't make sense to me.
Assume a 5-channel amp, with all channels initially set to manufacturer's specified bias current using DVM. If you "go the wrong way" (i.e. reduce current) on one of the channels in your first stereo pair for the listen/match test, you'd be setting its idle current to below the manufacturer's spec. If you the did the same for the other channels as you form up new stereo pairs for your listen/match test and adjustment, you could conceivably end up with only a single channel out of the five at the bias spec and all other channels operating somewhat or significantly below the manufacturer's spec. That doesn't sound like a winner to me as many things (all negative) could be affected by output legs starved of the current needed to operate in their linear output range.