We had several customers of power line filters and power amps complain of buzzing sound.
We had to go into a really quiet room and put ears to it up close. yes, there was something there. It was, in one case, ferrite core itself and in another case, a power transformer near a steel top caused the top to vibrate.... rubber damping between transf and top damped it. Potted cores on the ferrite killed vibration. These are really low levels,too. But, customers returned the products to their stores..... not just one person.... it annoyed them. Many of them returned the products for that reason and we (Engineering) had to figure out what and where and how to fix issues.
So, don't under-estimate what customers can or cannot hear or tolerate.
THx-RNMarsh
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Output transistors as we know throughput what can be very high instantaneous currents.
One of our friends here posted an internal photo of his Marantz amplifier.
Noteworthy was the inclusion of formed (shiny) copper plates covering top and three sides of each of the output transistors.
These covers would provide very effective screening and quenching of stray fields emitted by high output half wave currents....Marantz secret sauce ?.
I have encountered plenty of cheap gear using steel plates as output ic or transistor hold-downs....in quick experiments I have removed these plates and the sound of these output stages lost a 'harshness' that don't belong....beware these kinds of small details.
Microphonics and these extraneous 'loadings' can be disastrous also.....last Friday night I ran full treatment on backline, production and PA for my friend Michael Vdelli's last show here for the season.
By halfway through the first set we had the system sounding pretty good except....something wasn't quite right.....vocals and guitar were sounding 'loaded down' with loss of clarity and wrong dynamics and wrong 'tone'.
So, I went searching and found that a small heavy bag full of strings and other stuff/junk had been placed on top of the stage right stage box, right on top of the XLR's.
Removing this bag restored 'naturalness' to the sound, but now revealed was another problem with the (copious) bass.....a bit muddy and wrongly resonant.
Moving the mixing desk/production console forward from the back wall by about ten inches and then tweaking the position by an inch or so fine tuned the overall sound to magical.....the crowd moved to stage front with smiles all round and 'love in the air'....it was a fun night.
Tuesday we are going up country to a 110 years old pub to record his new album....I will be fully treating power, backline and the recording gear.
Based on prior experiences I expect this will be a landmark recording of sorts, we will see.
Dan.
One of our friends here posted an internal photo of his Marantz amplifier.
Noteworthy was the inclusion of formed (shiny) copper plates covering top and three sides of each of the output transistors.
These covers would provide very effective screening and quenching of stray fields emitted by high output half wave currents....Marantz secret sauce ?.
I have encountered plenty of cheap gear using steel plates as output ic or transistor hold-downs....in quick experiments I have removed these plates and the sound of these output stages lost a 'harshness' that don't belong....beware these kinds of small details.
Microphonics and these extraneous 'loadings' can be disastrous also.....last Friday night I ran full treatment on backline, production and PA for my friend Michael Vdelli's last show here for the season.
By halfway through the first set we had the system sounding pretty good except....something wasn't quite right.....vocals and guitar were sounding 'loaded down' with loss of clarity and wrong dynamics and wrong 'tone'.
So, I went searching and found that a small heavy bag full of strings and other stuff/junk had been placed on top of the stage right stage box, right on top of the XLR's.
Removing this bag restored 'naturalness' to the sound, but now revealed was another problem with the (copious) bass.....a bit muddy and wrongly resonant.
Moving the mixing desk/production console forward from the back wall by about ten inches and then tweaking the position by an inch or so fine tuned the overall sound to magical.....the crowd moved to stage front with smiles all round and 'love in the air'....it was a fun night.
Tuesday we are going up country to a 110 years old pub to record his new album....I will be fully treating power, backline and the recording gear.
Based on prior experiences I expect this will be a landmark recording of sorts, we will see.
Dan.
Hi Richard,
So, you are quite right, but those folks are in a minority. Unfortunately in high end audio, they report on things more and you'll have people reacting to the "defect" even though they did not actually experience it. The power of the internet.
-Chris
True, but they are the exception. I had a customer that was bridging his Nakamichi PA-7 amps, driving them with a CA-7 preamplifier. He claimed that one channel had more noise than the other. Both channels beat spec, but one of those was about 8 dB worse than the other. I traced that down to a DC power lead that needed a shield placed between it and the audio electronics. After that "fix", both channels were roughly equal in background noise. I found out that this particular person would turn off everything in the house except for the stereo to listen. Fridge, furnace - air conditioner, everything. He was about one customer in ten thousand I'd guess. He must have driven the folks that made the bridging adapters bonkers! They were not high quality units, and I tested those to make sure the cause wasn't there before getting into the preamp.
So, you are quite right, but those folks are in a minority. Unfortunately in high end audio, they report on things more and you'll have people reacting to the "defect" even though they did not actually experience it. The power of the internet.
-Chris
http://aries.ucsd.edu/NAJMABADI/CLASS/ECE102/12-F/NOTES/ECE102_F12-LecSet-6.pdf
A benefit of folded cascode.
-RNM
I've found at the end only this:
* Folded cascode only helps the voltage overhead issue for difference amplifiers
BR Damir
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I listened to this the other night and thought there were some nice takeaways which could be applied here:
Reality : Invisibilia : NPR
Reality : Invisibilia : NPR
Thanks Richard for putting up the cascode explanation. For most circuits, the folded cascode is more an added complication than anything useful. However, for the best design approach that includes direct coupling, minimum stage count for the signal flow, and very good linearity, it has most other circuits beat. It is hard to bias without knowing your device characteristics well, especially if you omit the current sources, as I do. I have nothing against IDEAL current sources, but I have never been able to make one, so I usually stick to resistor biasing, which requires a little more device selection, but also more optimum operating currents for the individual fets. The main problem with this circuit as Charles Hansen and I normal used it is that it has lower intrinsic gain than if the circuit was reconfigured to be 2 gain stages in series.
Scott Wurcer uses a single sided version of this topology with bipolar devices and current sources which overcomes the gain problem, but requires output buffers for optimum operation adding to the stage count, and trades one advantage for another.
Scott Wurcer uses a single sided version of this topology with bipolar devices and current sources which overcomes the gain problem, but requires output buffers for optimum operation adding to the stage count, and trades one advantage for another.
You guys are really overlooking topology when thinking about signal coupling capacitors. So far this has only been mentioned in respect to feedback caps. Depending on the equipment, you will hear more and less of the capacitor. Folsom's new amp is not half as sensitive to the input capacitor as the last one. It seems like some devices sort of come to an agreement between the whole chain of gear, and others tend towards indifference. You can guess which tends to reveal capacitor sonic qualities more. For the record the old amp didn't work with electrolytic inputs well at all, because it polarized them and made them sound bad. You could put a film cap in series with it, and it'd sound better... (it was bipolar lytic btw)
But to question whether they are audible or not is nothing short of absurd. Just because you haven't done all but one or two swaps in a piece of gear that may be fairly indifferent, does not mean they don't sound different. I have no doubt some are just sloppy and "different". But consider that Richard has worked with REL and they rank well... clearly there is something to it.
I'd like to point people to this page. Granted it isn't a perfect experiment for all uses of capacitors, but there is an evident correlation with subjective preferences and test results.
And I'll follow up with saying the differences in sound from swapping electrolytics on Folsom's latest amp's feedback section produces very different results. It's rather interesting. But, while the warning about using them vs. film is received... I have to tell you the ESY model from Kemet that I have settled on... it's pretty stellar in sound. (Easily better than the Parasound amps I've heard, but maybe that is poor AC power related?)
ESY Specs
Just because capacitors can sound different does not mean they will always impart the full sonic quality they can have. As I posted above, some equipment seems sensitive, other does not. Consider that if there is a strong DC bias it may also be eliminating microphonics the cap could be producing. (I know, that's a bucket of worms, but it is possible and some of my own tests seem to illuminate the possibility).
I've found several of those to be accurate. I have not been able to buy all the caps, nor want to, but it's a good reference for choosing one. The other link to laventure appears to be a nice shootout as well, perhaps I'll go with some of its recommendations. Either way I think at the least they can ward you away from some shitty caps.
DBT
Maybe if I drill this hard enough someone will eventually think it's their idea, and everyone will compliment them on it... I'm sure it's only like the 5th time I've mentioned in a JCBT thread... There is a sore need to try using relation to the sound, that is indifferent to the electronics. For example you make some large flash cards or LED's. Capacitor 1 is Red. Capacitor 2 is Yellow. You have them listen many times. Then introduce Green, which is either Capacitor 1 or 2, and they have to guess which. Another way is to tell them there are either 2 Reds or 2 Yellows, and which ever color there is two of the two capacitors (say yellow) are not the same capacitors. You continually switch between Red & Yellow, and the mystery R/Y capacitor & card. When they are ready they can guess which one it is....
There are a few ways to do it. The point is to tie an anonymous reference to try and ground the person in reality and see if they can start to form expectations for the colors, and hence know if they have heard their expectation or not (auditory recognization). This coincides strongly to how we hear in everyday life, and when we can recognize seemingly benign, blind, auditory events. We recognize sounds that we can't describe, frequently, but we have some kind of relationships to the sounds. How does someone that lives in an old apartment recognize every single persons walk going up the stairs, and knows when a guest is walking up them? They couldn't even remotely tell you what the sound is like offhand, but they know. Our memory of auditory things is mostly a form of expectation, and how and what our bodies, ears, and brain "expect" varies from person to person, surely.
P.S.
I thought Part II was just in a quiet moment... Then I discover I've got 49 pages to catch up on
But to question whether they are audible or not is nothing short of absurd. Just because you haven't done all but one or two swaps in a piece of gear that may be fairly indifferent, does not mean they don't sound different. I have no doubt some are just sloppy and "different". But consider that Richard has worked with REL and they rank well... clearly there is something to it.
I'd like to point people to this page. Granted it isn't a perfect experiment for all uses of capacitors, but there is an evident correlation with subjective preferences and test results.
And I'll follow up with saying the differences in sound from swapping electrolytics on Folsom's latest amp's feedback section produces very different results. It's rather interesting. But, while the warning about using them vs. film is received... I have to tell you the ESY model from Kemet that I have settled on... it's pretty stellar in sound. (Easily better than the Parasound amps I've heard, but maybe that is poor AC power related?)
ESY Specs
Just because capacitors can sound different does not mean they will always impart the full sonic quality they can have. As I posted above, some equipment seems sensitive, other does not. Consider that if there is a strong DC bias it may also be eliminating microphonics the cap could be producing. (I know, that's a bucket of worms, but it is possible and some of my own tests seem to illuminate the possibility).
I've found several of those to be accurate. I have not been able to buy all the caps, nor want to, but it's a good reference for choosing one. The other link to laventure appears to be a nice shootout as well, perhaps I'll go with some of its recommendations. Either way I think at the least they can ward you away from some shitty caps.
DBT
Maybe if I drill this hard enough someone will eventually think it's their idea, and everyone will compliment them on it... I'm sure it's only like the 5th time I've mentioned in a JCBT thread... There is a sore need to try using relation to the sound, that is indifferent to the electronics. For example you make some large flash cards or LED's. Capacitor 1 is Red. Capacitor 2 is Yellow. You have them listen many times. Then introduce Green, which is either Capacitor 1 or 2, and they have to guess which. Another way is to tell them there are either 2 Reds or 2 Yellows, and which ever color there is two of the two capacitors (say yellow) are not the same capacitors. You continually switch between Red & Yellow, and the mystery R/Y capacitor & card. When they are ready they can guess which one it is....
There are a few ways to do it. The point is to tie an anonymous reference to try and ground the person in reality and see if they can start to form expectations for the colors, and hence know if they have heard their expectation or not (auditory recognization). This coincides strongly to how we hear in everyday life, and when we can recognize seemingly benign, blind, auditory events. We recognize sounds that we can't describe, frequently, but we have some kind of relationships to the sounds. How does someone that lives in an old apartment recognize every single persons walk going up the stairs, and knows when a guest is walking up them? They couldn't even remotely tell you what the sound is like offhand, but they know. Our memory of auditory things is mostly a form of expectation, and how and what our bodies, ears, and brain "expect" varies from person to person, surely.
P.S.
I thought Part II was just in a quiet moment... Then I discover I've got 49 pages to catch up on
"1000 -5000 hours operating time, on the shelf: 1000"
-> 41 - 200 days ;-(
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And it's guaranteed life span, they fail after it, but when is unknown.
If it was only a few thousand hours that would be a major problem for longevity of any electronics.
John, I do have a direct coupled amp and it sounds very very good. It's and old Marantz 170DC, sandwiched between its 3200 pre amp and Klipsch Cornwalls. To quiet things down I'm using one of Richards HTPS 7000 MKIIs power systems as this room is connected to a four way wired circuit (I think that's the correct name, when wired from two outlets and either outlet can turn it on or off) of Florescent lights.
The digital source is a good phillips CD or the HK CD.
Changing things around from time to time can be revealing. In this case it showed my the ARC SP3A1 pre amp I'd been using has some issues with it's right channel.
It also showed me that the CitationII amp I've got wired up with four KT90s in triode mode sounds really really good.
Sadly, when I placed the Yamaha P2200 in the mix, it sounded really really bloaty in the mids. Just unnaturally thick and for an amp that powerful with these speakers it was really surprising and sickening to listen to it.
All this stuff makes a difference. And if we follow what Richard's been preaching here, that we have to measure the whole system, not just one particular piece.
They all interact with each other.
And with what John likes in his designs from what I've read, and what I've heard myself direct coupled gear is damn good sounding.
You've got to be careful with it too. It feeds through from your sources and if there's DC or a transistor goes....There go your speakers.
Let's just say one day I got something in to check out and in about 60 seconds I fried $1600 in drivers that I owned!
Oh Da Joy!
Cheers,
The digital source is a good phillips CD or the HK CD.
Changing things around from time to time can be revealing. In this case it showed my the ARC SP3A1 pre amp I'd been using has some issues with it's right channel.
It also showed me that the CitationII amp I've got wired up with four KT90s in triode mode sounds really really good.
Sadly, when I placed the Yamaha P2200 in the mix, it sounded really really bloaty in the mids. Just unnaturally thick and for an amp that powerful with these speakers it was really surprising and sickening to listen to it.
All this stuff makes a difference. And if we follow what Richard's been preaching here, that we have to measure the whole system, not just one particular piece.
They all interact with each other.
And with what John likes in his designs from what I've read, and what I've heard myself direct coupled gear is damn good sounding.
You've got to be careful with it too. It feeds through from your sources and if there's DC or a transistor goes....There go your speakers.
Let's just say one day I got something in to check out and in about 60 seconds I fried $1600 in drivers that I owned!
Oh Da Joy!
Cheers,
Wow - those jet boats are crazy, > 2500Hp / 200mph.
As for most dangerous sport, Isle of Man TT.
YouTube
No room for error.
T
I know, and I had seen the graphic (see attached)
What surprised me was: "On the shelf: 1000 Hours."
On the shelf at 105° ?
Not a good place to keep your chocolate bar.
Attachments
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As I said earlier.... life is where they will not meet the published specs any more. take the spec and double it and you have the "life" of the cap. ---> where leakage doubles, esr doubles, DF etc etc.
Or, the C is 1/2 etc etc.
Doesnt mean it out right fails.... just degraded to a point and how long it takes to get to that point. It continues to degrade after that.
105C do a lot better ... slower to degrade to same %age.
THx-RNMarsh
Or, the C is 1/2 etc etc.
Doesnt mean it out right fails.... just degraded to a point and how long it takes to get to that point. It continues to degrade after that.
105C do a lot better ... slower to degrade to same %age.
THx-RNMarsh
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