If the stability of your amplifier is that sensitive to the ESR and ESL of any capacitor in the circuit, you're doing something wrong. I can see a requirement to keep the ESR below a certain value and/or the SRF above a certain value, thereby keeping the ESL below a certain value. However, if your amplifier requires the ratios of capacitance, ESR, and ESL to fall within certain ranges, I suggest going back to the drawing board as you probably have a fundamental flaw in your architecture.
Tom
You may not need specific values in designs, but specific values do help optimize. That is why people are hearing differences between different capacitors.
Presupposes people hear the difference between small differences between caps. Or that the capacitors in question are so drastically different as to grossly affect the response of the circuit. One would typically consider a part that, due to it's nonlinearities, affects response of the circuit worth replacing.
For the stability scenario you mentioned a few posts back, you will need a specific value. Optimization (using measurements) may result in a slightly different final value. That does not mean you can just pick any value out of thin air.
Citation needed.
Have you read any of my posts? Many measurements correlate with the perceived sound quality. That's my experience as well. By "measurements", I mean measurements of the completed system. Anyone claiming to be able to hear the difference between a capacitor with 20 mΩ ESR and another with 25 mΩ ESR aught to either back up their claims with a controlled experiment or get their head examined.
If one film was polypropylene and the other, say, polyester then you would be able to measure a difference in THD of the capacitor. Doug Self did this many moons ago. The nation of origin is irrelevant to the material properties.
Tom
Whether ESR makes a difference or not, in the line signal circuits, I find it hard to believe such difference would make an audible difference since it has little effect on the SRF characteristics. Generally, I would try some expensive capacitors to see if the will make an audible difference, if it makes a positively audible difference, then I will see if there are measurable difference of the components that may reasonably correlate with what is heard, different types of measurements are done until a test condition is confirmed, then other capacitors of the same insulation material until the test is reasonably reliable.
Even same insulation material type can have different properties because of the conducting material and bonding/depositing method of the plates as well as the cap structure.
Even same insulation material type can have different properties because of the conducting material and bonding/depositing method of the plates as well as the cap structure.
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How is the price relevant if you're trying to determine the effects of ESR on perceived sound quality? You could easily change the ESR of a cap by adding series resistance to a low ESR cap.
It sounds like you're working backwards. Now, how you work is your decision, but it sounds like you are trying to find reasons why the expensive capacitors "sound better" without validating whether the expensive capacitors actually do "sound better" than inexpensive capacitors. One person performing a sighted test with knowledge of the cost of the components does not pass any standard for scientific testing. You can go a couple of pages back in this thread and see my rationale for why design decisions should not be based on sighted listening tests.
Tom
First of all, there are not many reviews of cheaper capacitor, and I do respect the reviews to a certain degree before I have experienced them personally.
When you add a series resistor to a low ESR cap, you are also adding a none ideal resistor model as well depending on the type of resistor. This is not the same as a single cap.
When you add a series resistor to a low ESR cap, you are also adding a none ideal resistor model as well depending on the type of resistor. This is not the same as a single cap.
Considering that reviewers have a hard time even agreeing on their language (see my previous comment about polar opposite terms used to describe the same phenomenon) I have a hard time taking them seriously unless they include measurements.
That is correct. However, even leaded metal film resistors are dominantly resistive from DC past 40 MHz (the measurement limit on the HP4194A Gain-Phase/Impedance analyzer I was using).
Tom
I cannot speak for others, but I actually think the old days had better description. Since I have been a pure audiophile with limited knowledge of the details, anything that has to make an audible difference to me. Once there is an audible difference, then I can look into the pros and cons technically and through listening. I would say, if you swap different brands of components and don't hear a difference, don't worry about it.
In some circuits I hear difference using different resistors and solders as well, so I just have to make a choice what it's going to be. For these cases, I really do not spend time measuring, just a listening decision and cost consideration to determine if the added cost is worth the difference. I do this to make sure I will be getting the as close sound quality from unit to unit as possible meaning once the brand and model of components are fixed, then no change until the new selection gets evaluated. This then becomes the reference where all development circuits use the same until there is a good reason for change.
The capacitor case was one process where a factory said they OEMed a certain brand and model. When it did not sound the same, and I proved it to them, I was sent a few different configurations to test. Did find one that compared well audibly and in measurements.
In some circuits I hear difference using different resistors and solders as well, so I just have to make a choice what it's going to be. For these cases, I really do not spend time measuring, just a listening decision and cost consideration to determine if the added cost is worth the difference. I do this to make sure I will be getting the as close sound quality from unit to unit as possible meaning once the brand and model of components are fixed, then no change until the new selection gets evaluated. This then becomes the reference where all development circuits use the same until there is a good reason for change.
The capacitor case was one process where a factory said they OEMed a certain brand and model. When it did not sound the same, and I proved it to them, I was sent a few different configurations to test. Did find one that compared well audibly and in measurements.
I was surprised myself, but when two boards sound different, and all components are the same, I noticed one side sounded brighter than the other, I remembered I used leaded solder (wonder solder) in one channel, and unleaded from MG chemicals in another, resoldering the unleaded to leaded balanced the sound. Really cannot say which one is better, but leaded solder does give more punch in the bass. Then I did try different solder leaded and unleaded, each just sounded different, so I just stuck with MG chemical since I am going unleaded. This is something I did not expect. It just happened and I got curious...
But not curious enough to set up a scientific experiment. You know... Multiple circuits, randomly selected to be either leaded and unleaded. You then blindly select between them in your listening trial and write down which sounds leaded and which sounds unleaded. If you can get results that are statistically significant beyond the results you'd get by chance, I'll believe you. You can look up ABX testing if you're curious.
Man... I think H.C. Andersen was onto something in The Emperor with no Clothes. Who knew he was really writing about audio testing.
Tom
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Yeah, I think we've regressed far enough. Perhaps those who wish to discuss the sonic impact of barometric pressure changes on the perceived sound quality in their sighted N = 1 trials would be so kind and start a thread in the lounge. That'll be a big help for those of us who prefer to take a scientific approach to audio design. I'll check in on the thread periodically as time allows.
Thanks.
Tom
Well, I hate to derail this thread, but I thought I'd post a pic...
No chassis yet. I want to integrate a volume control, so more parts on the way for that. Right now, I'm using an external pre-amp for volume control duties.
Currently, signal in/out is all single ended, but will be fully balanced input once volume control is sorted.
For the record, I did use Cardas Quad Eutectic solder for the build... Flows very nice! Though I'm not sure it sounds any different than anything else.
Probably the best thing I can say about the Mod86 is that there is nothing wrong with the sound. I don't know if its "fast" or "sparkly" or if it has PRAT or ... It just sounds Right
Thanks for all the engineering time you put into this one, Tom. I guess this makes me a fan!?! I'll wave the pom-poms, as long as I don't have to wear the skirt!
No chassis yet. I want to integrate a volume control, so more parts on the way for that. Right now, I'm using an external pre-amp for volume control duties.
Currently, signal in/out is all single ended, but will be fully balanced input once volume control is sorted.
For the record, I did use Cardas Quad Eutectic solder for the build... Flows very nice! Though I'm not sure it sounds any different than anything else.
Probably the best thing I can say about the Mod86 is that there is nothing wrong with the sound. I don't know if its "fast" or "sparkly" or if it has PRAT or ... It just sounds Right
Thanks for all the engineering time you put into this one, Tom. I guess this makes me a fan!?! I'll wave the pom-poms, as long as I don't have to wear the skirt!
Attachments
Those heatsinks are NOT messing around! And nice chassis.
+1
Probably the best thing I can say about the Mod86 is that there is nothing wrong with the sound. I don't know if its "fast" or "sparkly" or if it has PRAT or ... It just sounds Right
Thanks for all the engineering time you put into this one, Tom. I guess this makes me a fan!?! I'll wave the pom-poms, as long as I don't have to wear the skirt!
Nah. I won't make you wear the skirt. Remember. You can't un-see things. I'll go poke out my mind's eye now. Thanks!
Thanks for the laugh. I'm glad you like the amp and appreciate the work I put into it.
Tom
