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heady

Building the amp5

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Thanks CK. I bought a used 7x4.5cm heat sink from Koba for the Tripath chip. Now trying to figure out how to attach it. For the regulator, I am intending to epoxy a long thin aluminium heatsink to the back of the clip-on and epoxy more little fins to the aluminium strip.

 

Can't use the heatsink you suggest in the pic above for the regulator. There is a little electrolytic capacitor beside the regulator which gets in the way. :(

Edited by heady

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Thanks CK. I bought a used 7x4.5cm heat sink from Koba for the Tripath chip. Now trying to figure out how to attach it. For the regulator, I am intending to epoxy a long thin aluminium heatsink to the back of the clip-on and epoxy more little fins to the aluminium strip.

 

Can't use the heatsink you suggest in the pic above for the regulator. There is a little electrolytic capacitor beside the regulator which gets in the way. :(

 

Hmm, wouldn't epoxy be inefficient at heat transfer? You can also try those U shaped heatsinks for the regulator, commonly available at places like Koba, etc.

 

Regards

CK

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I am using epoxy for 2 reasons, ok 3.

1 - Tangent has done some tests on the heat transfer of epoxy and he found epoxy to be quite ok.

2 - I am using steel impregnated epoxy ($4.50 from hardware store)

3 - only a very thin layer is required

 

The clip on heat sink is the usual U shape thingy. I stuck the flat long heatsink to the back of the U and stuck another U thingy higher up. Real ugly but hope it works out ok. If not, all I lost will be some heat sinks, as the whole thing is clipped on only.

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Added pic of heat sink on pcb.

 

The Tripath heat sink from Koba - still available but need to drill the holes yourself. Best to do this before mounting the chip, otherwise very difficult to get the spacing just right.

 

Regulator heatsink - clip-on from Koba, two other heatsinks epoxied on from SLT.

amp5_01_02.jpg

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Finished some mods to the amp5:

1. Changed the input capacitors to Solen 3.3uF and bypass with a small Vishay-Roedenstein 0.01uF. Both polypropylene.

 

2. Changed the outfilter caps to Rifa/Evox 0.22uF polypropylene.

 

3. Added (just for fun) one Rifa/Evox 1uF polypropylene bypass to each large rail power capacitor.

 

Since I also added silver-coated wires to connect up to the RCAs, I don't know which change benefits the most but the sound is so much cleaner and clearer. However, the extended bass and treble make the amp sound a little like it is in "Loud" mode.

 

At low volume, it really sound good. Anyway, I can't test it loud tonight, it's too late. Btw- with the heatsinks, both the Tripath and regulator are in the mid-40s Celcius and lower.

 

Thanks to CK for suggesting this amp.

Edited by heady

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Finished some mods to the amp5:

1. Changed the input capacitors to Solen 3.3uF and bypass with a small Vishay-Roedenstein 0.01uF. Both polypropylene.

 

2. Changed the outfilter caps to Rifa/Evox 0.22uF polypropylene.

 

3. Added (just for fun) one Rifa/Evox 1uF polypropylene bypass to each large rail power capacitor.

 

Since I also added silver-coated wires to connect up to the RCAs, I don't know which change benefits the most but the sound is so much cleaner and clearer. However, the extended bass and treble make the amp sound a little like it is in "Loud" mode.

 

At low volume, it really sound good. Anyway, I can't test it loud tonight, it's too late. Btw- with the heatsinks, both the Tripath and regulator are in the mid-40s Celcius and lower.

 

Thanks to CK for suggesting this amp.

 

Sounds good. What speakers are you driving with the AMP5?

 

Regards

CK

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Sounds good. What speakers are you driving with the AMP5?

 

Regards

CK

 

A 20+years old pair of Arcams 2-way with 6inch woofer. Got surprising bass with this amp.

 

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oh, so heady has already finished the amp, and with some mods to it. i think the change of the caps do really cleans up the sound huh. any particular reason to make you decide to get those caps?

 

ok, i think i should be able to start the week after next...hope can clear up all my stuff at hands first...so maybe need your help then.

 

so the transformer is farnell #696985?

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oh, so heady has already finished the amp, and with some mods to it. i think the change of the caps do really cleans up the sound huh. any particular reason to make you decide to get those caps?

 

ok, i think i should be able to start the week after next...hope can clear up all my stuff at hands first...so maybe need your help then.

 

so the transformer is farnell #696985?

 

1) After reading the amp5 forum and also the diyaudio Class D forum, the most common mod is to change the electrolytic input caps to polypropylene. Most people will recommend boutique caps but I don't want to spend too much so I just bought Solens ($4 each) from Well Audio.

 

Bypassing the Solens with the Vishay-Roedenstein 0.01uF cap (http://sg.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=3038543) was from an article comparing the different input caps. It mentioned that whatever was used, using the Vishay to bypass them improved the sound. And since I could get it from Farnell ($2.58 each), I did so.

 

2) I have many Rifa polypropylene caps in my stock box from the early diy days when I just bought them because they were polypropylene. I later found them to be too dark for input caps, they block too much treble so I did not use them. However, Rifa caps are well known for power filtering applications.

 

Since I have Rifa caps with the right values (0.22uF) for the output filtering, I used them. Class D amps have lots of high frequency artifacts from the switching and the output filter is to remove them, so I thought the Rifa dark nature should help in this application. This is just my thought, no proof whatsoever that I am right. :)

 

I also used the 1uF for bypassing the power caps since I have them. There are opinions in audio forums that this helps to improve the sound. But I am just doing it because I already have them.

 

3) The sound is now just as I like it, very clean and detailed and yet with bass extension. There is still a little too much treble but not enough to to be fatiguing. It shows up in sibilances when the recording has too much, ie not every recording will have sibilance.

 

4) The transformer is the right one. You can also use two 12-0-12 toroids to make one 24-0-24 if you want to use a smaller case. This transformer is so big, it will require a minimum 5inch high case.

Edited by heady

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If you want to get more power out of the amp, here is the additional rectifier which can be ordered from 41Hz, buy from Farnell only $3.74. But you need to get the 10000uF caps from Sim Lim, probably either Wells Audio or Martin will have them.

 

http://sg.farnell.com/jsp/endecaSearch/par...jsp?SKU=4084888

 

May think of getting this later, when itchy fingers start twitching. :grin:

 

 

kross and CK, if you have not ordered the transformer, you may want to consider two of this:

http://sg.farnell.com/jsp/endecaSearch/par...jsp?SKU=9530606

 

Edited by heady

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Finished some mods to the amp5:

1. Changed the input capacitors to Solen 3.3uF and bypass with a small Vishay-Roedenstein 0.01uF. Both polypropylene.

 

2. Changed the outfilter caps to Rifa/Evox 0.22uF polypropylene.

 

3. Added (just for fun) one Rifa/Evox 1uF polypropylene bypass to each large rail power capacitor.

 

Thanks to CK for suggesting this amp.

 

Hi Heady, so you bought how many solen caps and vishay caps? how many caps are there anyway? 2 inputs 2 output? I would like to change the caps to polys too...

 

and how you bypass the solens using the vishay?? very hard to understand without schematics leh..

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Here are pics of my board. I am about to case the amp:

 

IPB Image

This shows the Solens beside the aluminium heatsink. There are leads attached to the Solens which are then soldered into the sockets which the input caps should go in. The Solens are glued down with silicone glue. The Vishays are under the board.

 

You will notice the top left big electrolytic cap is not in line, I could not place it in the holes as it will interfere with the regulator heat sink. So I turned the cap 180degrees and soldered a wire to the leg hanging in space. Look at the pic of the bottom of the board to see how the wire was attached.

 

IPB Image

Another view of the top of the pcb. Yes, I succumbed to temptation and put in the extra rectifier and caps. Got them from Koba. Nichicon 10000uF. The rectifier is not exactly the same but has higher specs, 12A. Koba did not have the same 8A GBU rectifier.

 

IPB Image

Bottom of pcb - the large caps at top are 1uF, bypassing the big electrolytic power caps. The small blue caps on right top are the Vishays, soldered in parallel to the Solens. The blue caps on left bottom are the output filter caps. The top has no space for these two, as these are much larger than the original caps.

 

kross - if you still need explanation for the input caps, please let me know.

--edit-- added pic of the Solens and the wires connection to pcb:

IPB Image

 

 

BTW - I think I did a really messy job with the Solens. Looks terribly sloppy now. If I do it again, I will mount the Solens beneath the board. I don't know why I didn't think of it earlier. Please pardon the lousy soldering and layout.

 

Edited by heady

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Hi Heady, so you bought how many solen caps and vishay caps? how many caps are there anyway? 2 inputs 2 output? I would like to change the caps to polys too...

 

and how you bypass the solens using the vishay?? very hard to understand without schematics leh..

 

I bought two Solen 3.3uF and two Vishay 0.01uF. The caps are placed in parallel. The polypropylene caps are not polarised, so it doesn't matter re: positive and negative.

 

Edited by heady

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If you want to get more power out of the amp, here is the additional rectifier which can be ordered from 41Hz, buy from Farnell only $3.74. But you need to get the 10000uF caps from Sim Lim, probably either Wells Audio or Martin will have them.

 

http://sg.farnell.com/jsp/endecaSearch/par...jsp?SKU=4084888

 

May think of getting this later, when itchy fingers start twitching. :grin:

kross and CK, if you have not ordered the transformer, you may want to consider two of this:

http://sg.farnell.com/jsp/endecaSearch/par...jsp?SKU=9530606

 

However the 2-transformer solution is going to cost quite a bit more. :( I am now deliberating between 18-0-18 toroidal (and lose some power) or a 20-0-20 EI monster :P This will ultimately determine which case I can get. Of coz, one more solution if I go with the monster is to have a nice slim case for the amp and have the transformer in an separate external casing. :D

 

Regards

CK

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IPB Image

Cased in an enclosure from Bytetronic. Left is power switch and right is mute switch, the LED comes on when the amp is in the mute state. Forgot the pic of the back - will do it tonight.

 

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