Hi,
the safest way is to connect all the exposed conductive parts direct to the Safety Earth.
This may give rise to hum/buzz/interference problems.
Instead, inserting a Disconnecting Network between the Safety Earth and Audio Ground, if done properly, can give almost the same level of protection. This Disconnecting Network must be capable of surviving longer than the mains fuse when asked to carry fault current to earth. This fault current can run to kA.
Note,
the Safety Earth is still permanently bolted/welded to the chassis.
I think you have shown a 10k & 330pF low pass filter (3.3uS) on the input. This is too severe and will cut a lot of treble.
Aim for between 0.5uS and 1.5uS.
I suggest the 10k be reduced to 2k0
the safest way is to connect all the exposed conductive parts direct to the Safety Earth.
This may give rise to hum/buzz/interference problems.
Instead, inserting a Disconnecting Network between the Safety Earth and Audio Ground, if done properly, can give almost the same level of protection. This Disconnecting Network must be capable of surviving longer than the mains fuse when asked to carry fault current to earth. This fault current can run to kA.
Note,
the Safety Earth is still permanently bolted/welded to the chassis.
I think you have shown a 10k & 330pF low pass filter (3.3uS) on the input. This is too severe and will cut a lot of treble.
Aim for between 0.5uS and 1.5uS.
I suggest the 10k be reduced to 2k0
AndrewT said:
Tks mr andrew,
the treble just OK, but worth for a try. the smaller value caps, will they also cut the low bass?
I was trying 1K0 i/o this 10K, mm i like the smooth acceleration, or you think there's a quality degradation due to this 10K?
FYI, i using preamp for tone control, and by pass mode. some record need a little adjustment.
Brgds,.
Eka
Laws vary by country, but the main point doesn't vary.
Safety earth (grounding) is about having touch-able metal surfaces as not different than the earth.
However, its also about facilitating the function of fuses and circuit breakers.
That's why I'd like your potentiometer knob either plastic or not different voltage than the faucet (kitchen system).
You can measure that with a multimeter (ohmmeter).
In the U.S. and many other places, there shouldn't be resistance between neutral and ground at the wall outlet. One exception is rural Australia, where there may be a maximum of 10 ohms (on rural single wire distribution networks). Check with your local electric codes for more information.
However, there should never be voltage between neutral and ground at the wall outlet. If that is the case, then the home electrics are needing a repair as quickly as possible.
On a lighter note,
I'm up early with plans to make your hot-rod LM1875, since the transformer has finally arrived and I found the 100uF caps. Back on the topic that's not fun, but necessary, I'm going to add an extra screw to the heatsink, and attach a ground to remove hazard of insulator slippage. Then I'll follow AndrewT's suggestions on safety earth grounding.
Maybe good if I post a photo?
Anyway, the photo would be very funny with the power supply and transfo being so many times larger than the tiny amplifier next to it.
But, a good photo is probably clearer information than anything I could write.
Safety earth (grounding) is about having touch-able metal surfaces as not different than the earth.
However, its also about facilitating the function of fuses and circuit breakers.
That's why I'd like your potentiometer knob either plastic or not different voltage than the faucet (kitchen system).
You can measure that with a multimeter (ohmmeter).
In the U.S. and many other places, there shouldn't be resistance between neutral and ground at the wall outlet. One exception is rural Australia, where there may be a maximum of 10 ohms (on rural single wire distribution networks). Check with your local electric codes for more information.
However, there should never be voltage between neutral and ground at the wall outlet. If that is the case, then the home electrics are needing a repair as quickly as possible.
On a lighter note,
I'm up early with plans to make your hot-rod LM1875, since the transformer has finally arrived and I found the 100uF caps.
Back on the topic that's not fun, but necessary, I'm going to add an extra screw to the heatsink, and attach a ground to remove hazard of insulator slippage. Then I'll follow AndrewT's suggestions on safety earth grounding.Maybe good if I post a photo?
Anyway, the photo would be very funny with the power supply and transfo being so many times larger than the tiny amplifier next to it.
But, a good photo is probably clearer information than anything I could write.
danielwritesbac said:
Seems there is no codes about this in my country. i didn't find anything.
Since the safety issue in my previous portable project, i start to check all related if there are parts un-properly grounded in existed 'kitchen amp'.
Theres no problem in the upper case ( amp ) . maybe in source box, i haven't open it.if the tone control activated, not if by passed, 2 of control pot ( not all ) knobs still humming when touched. yes they hv metal parts( the knobs ) i changed 'em with all plastic knobs, in near future i will open the case to check the pots, if i maybe missed in 'grounded' em. i missed the noise last time because i rarely use it. i think this grounding thing is kinda unique,. once, i test 'the scary portable amp' by replacing the existed, the noise of these knobs are gone. technically they're alike.i sud learn more for this, and more experience with ohmmeter as per your suggestion.
i also still working on input caps setting, mr andrew t suggest for the smaller value. said the big 3.3 will cut much treble.but the additional 0.047 or 0.1 in combo really solved this,thts working for separated tweeter of my 3-ways. not change anything in my 2ways.
i'm stop a while for sightseeing this forum, for i'm a bit mixed up with many things.also my testing drivers.the 3 ways and the small 2 ways. maybe i did wrong from beggining for i was set NFB to maximize or maybe cheat the drivers perfomance.
The existed caps is 3,3/160V combo with 0.1/250V all polyprop.on 3-ways,they're good in flat mode.lets say good for diana krall live,its able to 'shows' the contrabass tone properly, no subwoofer needed. but not good for 80's record with their limited widhtband, example: madonna's 'crazy for you', will shows unnecessary low tone.more bad for 70's re-recorded musics. unecessary mean not synchron with the music, i think thats only 'sud be cutted'bias. different result for my 2ways.
- i'm considering to change the input caps with only 0,047to0.1, i like the repro but they're cut the low tone which needed on some record. then activate the subwoofer. but the low tone sounds unnatural from subwoofer.
- i'm considering the existing.without subwoofers, and let to hears all things in the records.
- think to make em' can be switched by a selector. and make more option input caps for vary musics. without the subwoofer ( than get more busy than just enjoying. )
see i'm thats complicated
mainly i still work on it.
i'm going too far on this 'kitchen amp', which firstly presented to my mom to hear her fav christian radio station in the morning. now all my fav cds placed everywhere in the kitchen
and maybe boring for others, sud i finished this thread?
oh yes ofcourse some photos will be more informative
It sounds like great fun in the kitchen! Its not boring.
For input filter caps there's one really important thing they can do besides just blocking DC.
In my opinion, the right input filter cap will "sound like" you're located at the place the recording is made, rather than inside the listening room. This is transparency.
It can make/help the transparent or perhaps euphonic effect (low frequency density--non thick sound).
For poly (MKP, polyester, etc. . .) and Hi-K ceramic, they will be the exact size listed in the Overture Design Guide spreadsheet; however, electrolytic may be 5 or 6 times larger capacitance value. In my opinion, excessive size (too big) input filter cap can possibly make the "tubby" extra warm bass sound. If/when that is true, then its also true of the NFB cap (if present).
When a bypass cap is used to adjust frequency response for personal taste, it can have great variety depending on size and also depending on materials used. Popular materials include silver mica, polypropylene, polyester and ceramic, and there's several types per each. Their function and price aren't related.
Sometimes an electrolytic or polypropylene audio type cap will have extra materials inside it that serve to provide the effects of a bypass cap. Notably, Elna is the manufacturer of most of the electrolytic types with inbuilt effects. The problem with these is their sudden strong effect--either you like it or you just lost a dollar. They are incredibly durable and powerful. Nichicon makes a small variety, FG and KZ, which are much more like ordinary capacitors--just very high quality. I've used these before, yet there's bypass cap possibilities and alternatives that do almost the same job.
What is the job? I think that the job of the input filter cap is transparancy, and that can be a problem. That problem, in my view, happens at the studio, and mainly on popular music. There seems to be an expectation that the owner of playback equipment will use equalizations. It is extremely difficult to meet this expectation with amplifier component choices (really tough to eq with your input filter cap); however, it is very easily done with a bandaxall (bass-n-treble knob) equipped preamplifier.
Well, that's all I've got. Its great to hear about the concerts in the kitchen. I'll bet that mom thinks its really entertaining.
EDIT: P.S. I just checked the diagram. The NFB cap is present. You can try varieties there, because the effect is similar to input filter caps. By that diagram, NFB of 150k, I'd try Nichicon KZ 22uF 100v, and bypassed with 0.047 economy ceramic.
However, if the NFB were the standard 22k, then the values would be larger and my specific recommend wouldn't apply.
For input filter caps there's one really important thing they can do besides just blocking DC.
In my opinion, the right input filter cap will "sound like" you're located at the place the recording is made, rather than inside the listening room. This is transparency.
It can make/help the transparent or perhaps euphonic effect (low frequency density--non thick sound).
For poly (MKP, polyester, etc. . .) and Hi-K ceramic, they will be the exact size listed in the Overture Design Guide spreadsheet; however, electrolytic may be 5 or 6 times larger capacitance value. In my opinion, excessive size (too big) input filter cap can possibly make the "tubby" extra warm bass sound. If/when that is true, then its also true of the NFB cap (if present).
When a bypass cap is used to adjust frequency response for personal taste, it can have great variety depending on size and also depending on materials used. Popular materials include silver mica, polypropylene, polyester and ceramic, and there's several types per each. Their function and price aren't related.
Sometimes an electrolytic or polypropylene audio type cap will have extra materials inside it that serve to provide the effects of a bypass cap. Notably, Elna is the manufacturer of most of the electrolytic types with inbuilt effects. The problem with these is their sudden strong effect--either you like it or you just lost a dollar. They are incredibly durable and powerful. Nichicon makes a small variety, FG and KZ, which are much more like ordinary capacitors--just very high quality. I've used these before, yet there's bypass cap possibilities and alternatives that do almost the same job.
What is the job? I think that the job of the input filter cap is transparancy, and that can be a problem. That problem, in my view, happens at the studio, and mainly on popular music. There seems to be an expectation that the owner of playback equipment will use equalizations. It is extremely difficult to meet this expectation with amplifier component choices (really tough to eq with your input filter cap); however, it is very easily done with a bandaxall (bass-n-treble knob) equipped preamplifier.
Well, that's all I've got. Its great to hear about the concerts in the kitchen. I'll bet that mom thinks its really entertaining.
EDIT: P.S. I just checked the diagram. The NFB cap is present. You can try varieties there, because the effect is similar to input filter caps. By that diagram, NFB of 150k, I'd try Nichicon KZ 22uF 100v, and bypassed with 0.047 economy ceramic.
However, if the NFB were the standard 22k, then the values would be larger and my specific recommend wouldn't apply.
danielwritesbac said:
Hi Daniel,
Transparency... whata great idea, i'm so stupid, tht sud be in my brain since the beginning
i/o mix uping things. Lets starts again..
do you mean the 0.047 in paralel with 22uF? ( see pic )
I'm failed to find the said nichicon types, but XYG, KX n VX. Matshushita FC series are the most recomended here, and they're available.
Attachments
![nfb%20seting[1].jpg](/community/data/attachments/89/89286-95ad6f014c372c74235a324004222d86.jpg)
eketehe said:Hi Daniel,
Transparency... whata great idea, i'm so stupid, tht sud be in my brain since the beginning
Lets starts again..
do you mean the 0.047 in paralel with 22uF? ( see pic )
I'm failed to find the said nichicon types, but XYG, KX n VX. Matshushita FC series are the most recomended here, and they're available.
You're not stupid.
Really good transparency can also bring with it a loss of efficiency because of less compression. That can make observation difficult. However, you can always tell. Its the option where you listen to almost every song all the way through. Its the option where you can hear "through" the speaker to the "other side" and hear the ambient sounds at the recording site.
For the bypass cap deal, little Hi-K ceramics marked 473, 103, 472, can make good results. So can the little polyester.
Another possible specific capacitor for that spot is Mallory/Cornell 22uF 100v SEK (105c rated). It doesn't need the help of a bypass cap.
Its audiophile grade for about 25 cents.
This isn't true of either the 50v version or the 250v version, so that one model is just a lucky find.
As far as other options, a small collection will let you compare and find the one that pleases. Most generally, there's more success with 100v rated caps at the NFB because the 50v caps "may" have greater compression that's more suited towards PA than Hifi.
With chip amps, you can do it by listening to female singers. If she's really angry, well try a different option.
AndrewT said:
Its not new. I'm just hoping its a shortcut.
Some components have compression artifacts in the audio band.
Selecting the cap for the NFB is the current discussion.
Scenerio 1
One might choose such that seems to make additional bass because that's exciting. It might be additional bass, but it might just be compression. This is a great time to see if the bypass cap practice can help. Maybe you can have your cake and eat it too? Maybe not.
Scenerio 2
Possibly, hopefully, one of the options is incredibly beautiful but seems to have slightly less bass than Scenerio 1. So, I didn't want anyone to overlook the lovely sounds possible if there aren't compression artifacts in the audio band at all.
Its like "what to listen for" on this particular component choice. The decision is quite difficult; but, given a small collection, it can be quickly narrowed down to two or three excellent choices.
These most likely involve scenerios 1 and 2 above.
danielwritesbac said:
You're going have to tell us your definitions for transparency, efficiency, and compression because that statement makes no sense using the standard definitions of the words.
danielwritesbac said:
Since when can a capacitor have compression? Read Rod Elliot's article on "Compression in Audio" to gain a better understanding of the definition of compression and how it applies to audio: http://sound.westhost.com/compression.htm
BWRX said:
A "compression artifact" in an audio component isn't quite the same thing as a compressor machine. No, its much worse. A compression artifact doesn't usually cover the audio band evenly.
That (a compression artifact) can be "most distracting" to the listener because it will block some of the ambients of the recording. Thus it will also draw attention to the loudspeaker instead of the music. This is the opposite of transparency.
The original poster is currently reviewing his collection of capacitors suited to use at the NFB.
This won't have a large effect. However, in his descriptions above, there was a description of a certain peakishness on some recordings. That could be increased or decreased (slightly) by this component selection. In my opinion, removing some of this distraction is a step towards greater transparency.
It is particularly interesting because the source is mainly popular music. That brings with it a very wide variety of non-standardized equalization requirements. It would be a great hardship to even hit the average via amplifier component selection. That's just the wrong tool for the job. The power amplifier module has the job of transparent amplification.
In my opinion, equalizations are most properly, and certainly more easily, done with the expected equipment for such, which is a bandaxall preamplifier. I also believe that many popular music recordings are made with the expectation that such equipment is in use because it is found on the majority of playback equipment.
Therefore I'd like to say that the amplifier and bandaxall (bass-n-treble knobs) preamplifier both serve useful jobs for enjoyment of popular music, and that these jobs are quite different.
It is my personal preference to put a bypass switch onto any equalization equipment, including the bandaxall preamplifier. In my opinion, that allows for leisure listening to be completely free of disturbances; however, the equalizations are nice to have available at the flip of a switch when one desires a more party-like presentation.
Isn't that so much more convenient than reaching for the soldering iron each time?
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