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In Reply to: Re: Hand Peeling Capacitors - Mr. Cheney/Infinicap posted by Brian Cheney on July 29, 2002 at 20:17:48:
You seem have to not only developed a good following, but there are those that have given high praise to the performance of several of the models you offer.Your word of mouth advertising is great. So I can't understand why you have even boosted of this high tolerance cap matching thing?
Are you struggling to justify the cost of your offered cap upgrade?
Let me say first of all, having purchased 1000 caps at a time from Peter Moncrief, and listened to many different recipes of his, I am well aware of the performance level offered by his caps. And while I had application for some of them I would in no way consider them to be among the best caps made and they are certainly no Audio Cap Theta.
That being said, the Infinicaps are not expensive made caps and they are not hand wound, nor would anyone want them if they were hand wound. If they were hand wound there would be no way to maintain any consistency in construction. They are machine wound until the last turn in which they are adjusted (by hand) to meet a target value.
Now about this high tolerance thing....
This statement you just made, "I have often demonstrated the sonic effects of changing our crossovers by as little as 0.0047uF in a 241uF package.", is completely ridiculous.
Differences in cap values as big as .1uf can't even make 1/10th of a db swing in the measured response of a speaker.
Most trained listeners need a full 1db swing in response to here any difference and most listeners can not discern any difference in response until there is a 2 to 3db swing.
Don't get me wrong here Brian, I applaud your QC efforts. I myself shoot responses of all our drivers and match them into pairs for the inexpensive kits we sell. I know how labor intensive it can be.
But give us a break man, my Clio measuring system can't even measure tolerance variations of that small.
Those caps will shift more than that by burn in time and by shorting that often takes place within the cap itself as they are used.
If you want to look at response shifts look to room responses. Room response can easily cause 4 to 5db swings.
If you are really that concerned with the consistency of the response of your speakers then maybe you should take a visit to the Mad board where the response one of your speakers, measured by a rather well respected individual, is under fire for its poor measurements.
This is a rather long thread with a lot of questions you might want to address: http://www.madisound.com/cgi-bin/discuss.cgi?read=204320
I believe this one is from the speaker owner: http://www.madisound.com/cgi-bin/discuss.cgi?read=204404
Those "frightening" measurements are posted here: http://www.murphyblaster.com/_index.html
I am sure your responses to the comments there would be welcome.
Follow Ups:
I don't see any point to responding to what you've said. You're basically telling me I'm full of it. You're welcome to your opinion.I haven't seen the "poor" measurements on the Madisound board, nor would I find them of any interest. I have measurements on the RM 1 that are very flat, but I'm sure that's of no consequencer to you or the Madisound testers. As I have pointed out measurements not carried out with extreme care can make any system look like a poor performer. I just related my experience measuring the Spica TC 60's entire first production run on the VMPS Forum at harmonicdiscord.com.
If you don't want to go there, I'll summarize:The TC 60 was a system designed for a high degree of linearity that also paid attention to time alignment and antidiffraction. Drivers were preselected and pretested. Yet when we measured the finished product we found it difficult to obtain any kind of FR linearity, except at one mic position about 1.5ft from the system at a point 1" above the woofer frame. The system would then measure within 3 dB of flat on many units. Moving the mic 2" in any direction destroyed these measurements entirely. But I doubt anyone ever listened to the TC 60 at 1.5 feet from the baffle, with his ears on a plane 1" above the woofer basket.
Well Brian, I did not say you were full of it.I was not implying anything like that either.
But, I still have a hard time understanding why you stated, and now why you animately attempt to justify the need for maintaining unobtainable tolerances in your capacitors, especially in light of such greater discrepancies that are possible and common in other areas with much greater effect.
Also I find it hard to believe that you go to such extreme to maintain high QC regarding driver consistency as well yet could care less how one of your speakers has measured once it has left your shop (regarding the rather lengthy threads on the Mad board).
If any of my speakers measured with the 30db response dip and other problems that I saw posted of one of your speakers, I would be concerned. I would likely think something to be seriously wrong and I would be doing all I could to remedy the situation.
I am also not really sure what you meant when you related your experience measuring the Spica TC 60's?
Are you trying to say that despite your best efforts you could not produce a flat response with it as well?
Or are you saying that it sounded good despite the poor measurements? You did not mention how it sounded.
What was the point of that portion of your reply?
Danny, you should know better than to ask these questions.The tolerances I mention are not only obtainable and maintainable, I have been trimming every crossover to such tolerances for over 15 years. I understand if you don't care about tolerances, or can't hear the difference between the correct crossover point and the wrong one. I surely wouldn't advertise such a personal shortcoming on a forum like this, however.
I have total control over every aspect of the design and manufacture of our speakers. I can and do what I want. It is not your place to question why, as it would not be my place to critcize what you do. Why anyone would try to put such as highly regarded product as mine in a bad light is beyond me.
As for 30 dB notches and the like, I will assume tester incompetence.
The Spica story illustrates that when you measure speakers you have to put your mic where it measures best, not worst, even if that takes some doing.
"The tolerances I mention are not only obtainable and maintainable,"Tolerances that you are boosting can only be maintained for the mere moment you measure them. After that they will change. Those tolerances will change considerably after they have been burned in. Temperature will shift them. Plus, caps often short. It's a self healing process, but it will easily shift the value by more than the tolerance percentage you are shooting for. Dr.J even mentioned it could shift that much just from holding it in your hand. Considering he designs caps I wouldn't doubt it.
"I understand if you don't care about tolerances"
Oh I certainly do. I measure every driver that is sent out from here. Even our inexpensive $24.95 soft dome tweeters have a response curve of that tweeter attached to each one that leaves. I also measure each fully assembled speaker that leaves here as well.
The crossover components I use are generally better than 2%. If someone would like them even closer I can measure a few of them and pick some out that are better than 1%.
Even you just stated that your coils are held to only 1% tolerances.
Your resistors won't fall within 1% tolerances. Most are no better than 5% and still considered within specs.
If you are using some kind of variable L-pad (and it sounds like you are) the customer will never be able to turn them to the same setting twice or even come close to matching them to the cap tolerances you are claiming. They can be off more than 1% from one speaker to the next and the audible difference will not be heard. It can't be. The input isn't the same. Most of the time a completely different signal is sent to the right and left speakers.
When measuring a speaker it is to subjective to determine if the tweeter response looks better with a 6.800uF cap on it or a 6.9uf or a 6.7uF cap. It may make less than 1/10th of a db difference in the response curve. Moving the mic (or you ear) up or down 2" will make more difference.
"It is not your place to question why, as it would not be my place to criticize what you do."Oh, I don't question why you do it. I am not criticizing your actions in any way. I really don't care if you go to the effort or not. But, I am really surprised that you advertise it and expect well educated and knowledgeable members of the industry to see any value in trying to hold cap tolerances that close. I am certainly not the only one here that can't believe you are making such claims.
"Why anyone would try to put such as highly regarded product as mine in a bad light is beyond me."
No one, absolutely no one here, has said a single bad or negative thing about any of your products. In fact even those that are questioning your claims here about capacitor tolerances have had nothing but good things to say about your products. I also feel as if you are offering a good quality product for a really good price and I have no doubt it stands above the norm.
"The Spica story illustrates that when you measure speakers you have to put your mic where it measures best, not worst, even if that takes some doing."
This is also a completely ridiculous statement.
Do you also put your ear where it measures best too?
You should have a targeted design axis in the beginning before you even take the first measured response. You should never design a crossover then begin taking response measurements in different locations searching for the best response.
Personally I measure all our speakers in what I feel is listening axis or what might be ear level. Even our inexpensive kits are all within about a +/-2db range and most often than not measure smoother than that. Some have measured as good as +/-.75db.
Response measurements are posted on all our kits.
I also measure off axis response in the vertical and horizontal plane and post those responses too. This will give a better indication of what the room response might be.
"As for 30 dB notches and the like, I will assume tester incompetence."
Brian, I know the guy that took the measurements. It was taken at an ear level height. There were also several other speaker measured along with yours. This guy is VERY competent.
That was not it.
You are embarrassing yourself with an endless litany about how you measure speakers. I don't care how you measure and your measurements are of the crudest sort. You lack the training and ability to discern small but vital sonic differences and you seem determine to apply your own low standards to everyone else.Let's wait until your have my press clippings and professional recognition before you even question what I do or how I do it.
And yes, the RM 1 was measured incompetently if done in the manner you describe. The people involved should be ashamed of themselves.So should you.
"You are embarrassing yourself with an endless litany about how you measure speakers."If anyone is looking or feeling a little embarrassed here it is certainly not me.
"I don't care how you measure and your measurements are of the crudest sort. You lack the training and ability to discern small but vital sonic differences and you seem determine to apply your own low standards to everyone else."
A personally attack on me will not help you here. You also do not know me well enough to judge my training or ability.
And I mentioned my measurements because you said I didn't care about tolerances. I was in no way comparing my standards to yours.
"And yes, the RM 1 was measured incompetently if done in the manner you describe. The people involved should be ashamed of themselves."
Maybe you could tell us how that speaker should have been measured? If ear level is not the design axis then what is it? Please let us know?
"So should you."
I have nothing to be ashamed of. I have only asked you some questions, as have others. I think all here have been more than civil to you as well. It seams that only you have become offensive and have made personally attacks.
You have not answered anyones questions here and you are digging yourself into a hole. Maybe you should just stop now. It is getting pretty deap.
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