Amplifiers-speakers is an integral system. Changing one part may need adjustment in another part...
All speakers are clean if there is no amplifier. Cleanness of a speaker is determined by external factor (the amplifier) and internal factors in the speaker itself.
All things (frequency response, cleanness) are important. The farther we are from perfection, the more often we are faced with compromises. IMO, cleanness and flat FR are (depends on the criteria) subjectively easy to achieve.
What is a wet tantalum?? Doesn't sound so promising to me
The bigger the capacitance of specific capacitor model/type/brand, the "worse" it's intrinsic quality... (but 47uF to 100uF is no big difference).
For feedback cap, in term of capacitance alone, the bigger the better especially for bass response. For CFA (current feedback amplifier), where the HF is good but LF often suffers, I always use big capacitance. Small voltage type from computer's motherboards. I use 2 small diameter caps in my PCBs. Parallel Sanyo 1600uF or Sanyo Oscon 1000uF or smaller.
What is a wet tantalum?? Doesn't sound so promising to me
I know it sounds like an odd thing to try but it's THIS thread that gave me the idea.
In that thread I'm talking about my Onix, not the CA AM1. In the Onix I first tried a 100uF Nichicon KZ and found it was a touch bright in the upper midrange, I then fitted a 47uF Epos MMK polyester and found it was still a touch bright but the sound was cleaner. I now have a Solid tant (100uF) in and the sound is much better balanced but maybe a little lacking in bite or resolution (a touch soft I suppose).
I now have some K52-2 Russian mil spec Tants here to try. Will be interested to hear what they sound like.
FYI, one of the 48 diodes I measured for the article in Linear Audio was a Q-speed device: the LQA16T300. here is its datasheet . Readers of this thread may find themselves stimulated by the General Description at top right of datasheet page 1.
This Q-speed device finished 4th best (out of 43 diodes tested) on the power amplifier test @ 2 amps of load current. However it didn't finish nearly so highly on the preamp test @ 0.1 amps of load current; partly because the preamp test included some additional diodes with datasheet max current of only 1 amp, that weren't tested at 2 amps.
Did the Silicon Carbide diode finish higher than the Q-speed diode in the power amp test? Yes. Yes it did. Did a low cost "Soft Recovery Ultrafast Plastic Rectifier" finish higher than both of them? Yes.
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This Q-speed device finished 4th best (out of 43 diodes tested) on the power amplifier test @ 2 amps of load current. However it didn't finish nearly so highly on the preamp test @ 0.1 amps of load current; partly because the preamp test included some additional diodes with datasheet max current of only 1 amp, that weren't tested at 2 amps.
Did the Silicon Carbide diode finish higher than the Q-speed diode in the power amp test? Yes. Yes it did. Did a low cost "Soft Recovery Ultrafast Plastic Rectifier" finish higher than both of them? Yes.
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That feedback cap is part of a filter that affects the entire amp transfer function and was optimized for the amp. Changing the value will change the bandwidth and might cause instability. Which often comes across as brightness in the sound. Why do you think you know better than the designers?
I don't. That's why I asked the question in the first place.
Someone said 100uF will be fine. Are you saying that I should stick to 47uF?
The 1k/47uF in the nfb loop gives 3.4Hz. It would be better to have that around 2Hz.
That means C ~ 80uF, rather than 47uF, so use 100uF.
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Maybe not.
I adjusted down by an octave at a time until I could not hear any further improvement in the bass coming from a small speaker. I had in effect gone one octave too far. I could go back one octave and not hear any deterioration. But that was on a 5.25" bass mid driver. A really big speaker may show the extra bass.
This is a very simple experiment any Builder can carry out.
I ended up using ~90ms as the passive filter RC time constant = 1.7Hz
I get that with 1uF & 91k, or 10uF & 9k1, or any other combination that gives 90ms for RC.
I adjusted down by an octave at a time until I could not hear any further improvement in the bass coming from a small speaker. I had in effect gone one octave too far. I could go back one octave and not hear any deterioration. But that was on a 5.25" bass mid driver. A really big speaker may show the extra bass.
This is a very simple experiment any Builder can carry out.
I ended up using ~90ms as the passive filter RC time constant = 1.7Hz
I get that with 1uF & 91k, or 10uF & 9k1, or any other combination that gives 90ms for RC.
The advantage is more linear LF phase response. Also, there is less audio signal voltage
across the electrolytic capacitor, and so less dielectric distortion. Try it yourself on speakers
with decent quality bass and see.
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