Author Topic: Help needed with Project  (Read 1118 times)

Offline CAD

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Help needed with Project
« on: February 21, 2018, 04:44:46 PM »
Hello Chaps & Chappettes

Going to be needing some help with my next little project and will need to ask some noob questions along the way.
Advice and assistance would be appreciated.
Simple and in layman's terms if possible please and no cable discussions  ;D

Project is to upgrade/modify/make pretty a Behringer A500 amp.
Ok its not a terribly good amp but its unused and all I have to play with(Hifi related  :-X)
It will be a far cry from the Plinius, ML, Krell or even Rotel amps that I have had in the past but hey I can still have fun and learn.

I had a lot of fun and learnt allot from my last little project which was a DAC&Streamer set up.Will post some pics in a new thread shortly.

So basically this the scope and what I would like to achieve.

Replace Xunda Fong Kong Caps.
Replace or remove cr@py volume pots.Perhaps even bypass these to have the amp run at full steam
New front panel with blue illuminated power switch  :cool:
Bigger chassis
Add soft start and filtered IEC inlet
Add speaker protection.
Low cost
Have fun
Learn
Stay Safe and no magic smoke.

Anyone done any A500 mods they would like to share before I fire away with the questions



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Offline Ingvar Ahlberg

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Re: Help needed with Project
« Reply #1 on: February 21, 2018, 08:27:51 PM »
Quote
Replace Xunda Fong Kong Caps.
Replace or remove cr@py volume pots.Perhaps even bypass these to have the amp run at full steam
New front panel with blue illuminated power switch  :cool:
Bigger chassis
Add soft start and filtered IEC inlet
Add speaker protection.

That will be far more expensive than bying a better amp.

Ingvar
A senile Swedish loudspeakermanufacturer, ponytail and all, why is he here?

Responsible for H.A.D Halland Audio Design and The vacuumed cat Company.

Offline CAD

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Re: Help needed with Project
« Reply #2 on: February 22, 2018, 06:42:35 AM »
Could be if it includes a new chassis as I now see this can get quite pricey  :thinking:

Ok so little mini budget

Replace Xunda Fong Kong Caps : Only looking at replacing the 4x 3300uF 100V 105C for now.From what I have read and googled this seems to be the most common upgrade as the existing caps seems to be under spec for the power requirements.
Something like EPCOS Aluminium Electrolytic Capacitor 4700μF 100V dc @ R100 each from RS so thats R400 or Panasonic Aluminium Electrolytic Capacitor 4700μF 100V dc  R131ea from RS. Although it may be necessary to use can/screw terminal types as I think most of these have larger diameters than the current caps. Now we are looking at R300ea  :-\
This is one area I would need help and assistance

Replace or remove cr@py volume pots.Perhaps even bypass these to have the amp run at full steam : Volume pots could get pricey but have been reading about a simple mod with 20K resistor to bypass the volume control completely.

New front panel with blue illuminated power switch  :cool: Switch R54 from RS. I may do the front panel in wood or will chat to a bud who has a small machine shop for something.

Bigger chassis = TBD/on the back burner for now

Add soft start and filtered IEC inlet = Soft Start board $9(+shipping) from AliExpress. IEC inlet already have
Add speaker protection. = $15 From AliExpress(+ shipping)
These 2 items around R500 or R600

Have fun =Free
Learn = Free
Stay Safe and no magic smoke = Free(Hopefully)

So I guess I could do this for around R1000 or a little more depending on the caps chosen.
The way of the warrior is NO match for the way of the wife.
Light travels faster than sound. This is why some people appear bright until you hear them speak.

Offline Hi-Phibian

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Re: Help needed with Project
« Reply #3 on: February 22, 2018, 08:03:57 AM »
Parts from RS are expensive but you get whats on the bottle.  Doesnt matter for a 10 rand small cap but makes a difference on the big ones. 
With some care good caps can be bought for less from places like communica and MANTECH.

Bypass the volume pots. 

In to loony side. if the Amplifier has input signal dc blocking electrolytic caps replace those with Elna starget from RS.   (Back to back to make bipolar if needs be) Not expensive and well worth the sonic improvement over cheap ones in the signal path. 







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Offline MetalMilitia

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Re: Help needed with Project
« Reply #4 on: February 22, 2018, 08:33:47 AM »
Project is to upgrade/modify/make pretty a Behringer A500 amp.
Ok its not a terribly good amp but its unused and all I have to play with(Hifi related  :-X)

Apparently not a bad amp at all
https://forums.audioholics.com/forums/threads/behringer-a500-amplifier-objective-test-results.17004/

Offline Samayanaya

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Re: Help needed with Project
« Reply #5 on: February 22, 2018, 01:14:48 PM »
Could be if it includes a new chassis as I now see this can get quite pricey  :thinking:

Ok so little mini budget

Replace Xunda Fong Kong Caps : Only looking at replacing the 4x 3300uF 100V 105C for now.From what I have read and googled this seems to be the most common upgrade as the existing caps seems to be under spec for the power requirements.
Something like EPCOS Aluminium Electrolytic Capacitor 4700μF 100V dc @ R100 each from RS so thats R400 or Panasonic Aluminium Electrolytic Capacitor 4700μF 100V dc  R131ea from RS. Although it may be necessary to use can/screw terminal types as I think most of these have larger diameters than the current caps. Now we are looking at R300ea  :-\
This is one area I would need help and assistance

Replace or remove cr@py volume pots.Perhaps even bypass these to have the amp run at full steam : Volume pots could get pricey but have been reading about a simple mod with 20K resistor to bypass the volume control completely.

New front panel with blue illuminated power switch  :cool: Switch R54 from RS. I may do the front panel in wood or will chat to a bud who has a small machine shop for something.

Bigger chassis = TBD/on the back burner for now

Add soft start and filtered IEC inlet = Soft Start board $9(+shipping) from AliExpress. IEC inlet already have
Add speaker protection. = $15 From AliExpress(+ shipping)
These 2 items around R500 or R600

Have fun =Free
Learn = Free
Stay Safe and no magic smoke = Free(Hopefully)

So I guess I could do this for around R1000 or a little more depending on the caps chosen.

Don't buy from RS, they are expensive. Rather get from: www.digikey.com, www.farnell.com, Communica, Mantech. They are all cheaper and will you will get exactly what you want.

Offline Gerlach

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Re: Help needed with Project
« Reply #6 on: February 22, 2018, 03:02:36 PM »
Don't buy from RS, they are expensive. Rather get from: www.digikey.com, www.farnell.com, Communica, Mantech. They are all cheaper and will you will get exactly what you want.

Don't forget about Electrocomp. Always got some great serves from them and there prices is really good!! https://electrocomp.co.za/
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Offline CAD

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Re: Help needed with Project
« Reply #7 on: February 22, 2018, 03:35:08 PM »
Parts from RS are expensive but you get whats on the bottle.  Doesnt matter for a 10 rand small cap but makes a difference on the big ones. 
With some care good caps can be bought for less from places like communica and MANTECH.

Bypass the volume pots. 

In to loony side. if the Amplifier has input signal dc blocking electrolytic caps replace those with Elna starget from RS.   (Back to back to make bipolar if needs be) Not expensive and well worth the sonic improvement over cheap ones in the signal path. 

Anyone who thinks that wealth is measured in money is blind and narrow minded.  Wealth is obviously measured in turntables and records.]
Thanks so much G will consult with google fu on the dc blocking caps although I think one thread somewhere mentions this  :thinking:

Apparently not a bad amp at all
https://forums.audioholics.com/forums/threads/behringer-a500-amplifier-objective-test-results.17004/
Yes some mixed reviews though including this one which I found interesting.
http://matrixhifi.com/ENG_contenedor_ppec.htm

For what I paid its pretty darn good  :coffee:



Thanks everyone and yip RS does seem to be pricey but it's kind of my go to site for browsing and looking up stuff.
Mantech and Communica are know to me and will try the others as suggested  :2thumbs:

Is/are digikey local/in SA?




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Light travels faster than sound. This is why some people appear bright until you hear them speak.

Offline Trompie67

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Re: Help needed with Project
« Reply #8 on: February 22, 2018, 03:37:33 PM »
Don't buy from RS, they are expensive. Rather get from: www.digikey.com, www.farnell.com, Communica, Mantech. They are all cheaper and will you will get exactly what you want.

Farnell are now stocked (owned) by Avnet, so the entire Farnell catalogue is available from Avnet SA.
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Offline CAD

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Re: Help needed with Project
« Reply #9 on: February 22, 2018, 05:16:27 PM »
Tried to browse Avnet ,seems you to need to enquire about products you are looking for
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Offline CAD

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Re: Help needed with Project
« Reply #10 on: February 23, 2018, 08:21:48 AM »
Ok so here goes ,seconds out round No1

Replacing the 4 x 3300uf/100v 105c Caps

Question 1
From reading up it seems the caps are actually a little poof for the power requirements.
So can I replace these with a higher rating but same voltage and heat spec?
The pic below from www shows the guy replaced the caps with 4 X 10.000 F, 100 Volt. Is this overkill?

Question2
From what I can tell I would need to do a similar mod to the pic below as all the caps I am looking at have a larger diameter and probably wont fit on the board.
So my question is ,if the caps are away from the board & heatink could one go with a lower temp rating?In other words would 85c caps be sufficient.

Question 3
What makes the can/screw type caps so much more expensive ?

Question 4
How would one determine which caps are good for audio use?

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Light travels faster than sound. This is why some people appear bright until you hear them speak.

Offline pwatts

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Re: Help needed with Project
« Reply #11 on: February 24, 2018, 09:42:52 AM »
Digikey is stocked by Nuvision Electronics, Mouser by Electrocomp, Farnell by Avnet

If you buy >$200 direct, shipping with a courier is free with at least Mouser and Digikey.

RS is a mess with logistics and payment, but they sometimes do work out cheaper and stock brands not available elsewhere e.g. Wima.

Communica and Mantech is rolling the dice.. only use them if what you're buying is impossible to fake or does not require any quality or precision.

Offline Ampdog

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Re: Help needed with Project
« Reply #12 on: February 26, 2018, 09:51:21 PM »
So can I replace these with a higher rating but same voltage and heat spec?
The pic below from www shows the guy replaced the caps with 4 X 10.000 F, 100 Volt. Is this overkill?

Firstly, what do you mean by 'higher rating'? (I suspect you mean higher capacitance, but 'rating' would rather be used for the max. voltage and temperature.) Without viewing a schematic, decision on what is 'underrated' or what not is rather a thumb-suck business. Thus one hopes that the 3300F values were wisely chosen by the designer. Also from reading up it seems that the problem lies with Xunda rather than the capacitance value.

You will be lucky to find those values in a radial types. A Philips 330F-450V can type already measures 520mm x 36mm dia. I have Italian Kendeill 10 000F - 100V types here, measuring  880mm x 520mm dia. A much smaller format (size) will begin to be questionable.

The temperature value will depend on how warm it will be inside the power supply. 

Quote
How would one determine which caps are good for audio use?

Ah! There's a question surrounded by snake oil.

CAD, most if not all half-decent capacitors, are suited for audio. There is a certain piousness surrounding 'audiograde ....' and other similar qualifications.  :notworthy: :notworthy:

To put it politely, that is sales talk/urban-legend. Quick to add that some such claims may well describe a superior product; but is it necssary for audio??  Audio frequencies and -requirements are on the lowest end of capacitor specs.

[ :flame: It will be OT to open discussion on that here, perhaps later. If you are curious, PM me. ]

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Offline bushtech37

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Re: Help needed with Project
« Reply #13 on: February 26, 2018, 10:46:01 PM »
Ampdog

Methinks you've got 1 zero too many on your cap sizes

Offline CAD

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Re: Help needed with Project
« Reply #14 on: February 27, 2018, 03:33:31 AM »
Thanks oom Ampdog your valuable input is always appreciated and thanks for your offer to discuss via pm  :thumbs:
I have also since managed to get hold of a schematic and would value your input.Will discuss via pm.

Yebo higher rating in terms of capacitance is what I meant by higher rating.

You are quite right finding 4700uf/100v and higher replacements for the Xunda caps which are 25mm dia is proving to be near impossible .
Most 4700uf seem to be around 35mm in dia and 50mm in height and therefore I would guess mounting them on the chassis as per pic would be the way to go. This is where I started looking at screw terminal caps and found them to be a lot more expensive than snap in or through holes solder types.

As for the temperature from what I have read up I think it would be wiser to stick to the same spec as the original caps to ensure longer life span.

Quote
CAD, most if not all half-decent capacitors, are suited for audio. There is a certain piousness surrounding 'audiograde ....' and other similar qualifications.
Dankie oom this sets my mind at ease.Most of my subsequent reading up seems to indicate the same thing but has also left me somewhat confused. Low ESR ,high ripple current is what I need to get my head around now before taking the plunge  :thinking:
I have narrowed it down to what I think would be best bang for buck and RS has plenty stock 4-6 days delivery.
Panasonic Aluminium Electrolytic Capacitor 4700μF 100V dc 35mm Through Hole HA Type TS Series +105C  @ R131ea  OR
Nichicon Aluminium Electrolytic Capacitor 4700μF 100V dc 35mm Through Hole GU Series +105C @R163 ea.

This project is to have fun and learn bearing in mind the whole amp(used)did not cost much in the first place, so dropping +2K on caps is also not going to make sense nor make it a Krell  :giggle:










The way of the warrior is NO match for the way of the wife.
Light travels faster than sound. This is why some people appear bright until you hear them speak.