Hi there!
On a famous CDP mod therad, wise guys as Simon and Brent advised me to upgarde my Acram Alpha One (not1!!).
Did someone have done this?
Any idea for the caps? Others?
Thanks,
Matthieu
On a famous CDP mod therad, wise guys as Simon and Brent advised me to upgarde my Acram Alpha One (not1!!).
An externally hosted image should be here but it was not working when we last tested it.
SimontY said:
Did someone have done this?
Any idea for the caps? Others?
Thanks,
Matthieu
I'd be interested on what basis the claims are made that the caps are rubbish. Dubilier is a decent enough make. What output is the amp rated at?
6800uF is on the low side for a stereo mid-power amp. It certainly wouldn't hurt to upsize the transformer either.
6800uF is on the low side for a stereo mid-power amp. It certainly wouldn't hurt to upsize the transformer either.
35W I think. I have no idea of what has to be done, I just want to know what can be easy and cheap to improve some. Not rebuild it 😉
I'm almsot ready to invest on this one:
http://www.ornec.com/productim/100106/tw-2006-8.jpg
I'm almsot ready to invest on this one:
http://www.ornec.com/productim/100106/tw-2006-8.jpg
Oh dear, you've got me in trouble! lol
You need to trust your ears with the caps. Bigger capacity ones really could hurt the sound. Feel free to try though. I say this not because it's fashionable, but from some experience with two different amps of my own. Larger caps can improve the deep bass at the expense of everything else. The often talked about "snubber" of 1ohm and 100nF across the caps can bring the "freshness" back.
The rectifier diodes could affect the sound too, so consider "fancy" types here too, schottky etc.
The passive components are important, apart from those suggestions I can't offer much more because I don't know enough about how your amp was designed. Good luck with it.
Discussion of the "snubber":
http://www.diyaudio.com/forums/showthread.php?s=&threadid=48942&highlight=
Simon
You need to trust your ears with the caps. Bigger capacity ones really could hurt the sound. Feel free to try though. I say this not because it's fashionable, but from some experience with two different amps of my own. Larger caps can improve the deep bass at the expense of everything else. The often talked about "snubber" of 1ohm and 100nF across the caps can bring the "freshness" back.
The rectifier diodes could affect the sound too, so consider "fancy" types here too, schottky etc.
The passive components are important, apart from those suggestions I can't offer much more because I don't know enough about how your amp was designed. Good luck with it.
Discussion of the "snubber":
http://www.diyaudio.com/forums/showthread.php?s=&threadid=48942&highlight=
Simon
richie00boy said:
I withdraw the claim! I'll change it to "they don't look impressive"!
Caps that are larger for a given capacitance tend to be better specified and sound better. Black Gate, Elna Cerafine or Silmic, Siemens Sikorel (sp?) and BHC Aerovox are all said to offer good sound.
Matthieu,
If you can get a service manual perhaps someone here can point you to the most sensible components to upgrade.
Simon
I have the service manual, Arcam is very kind and offer it by mail. I'll put a link when I'll have uploaded it.
I must admit, that the whole construction doesn't look too impressive 
What catches my eyes is the potentiometers, the tiny cooling fins, and all the jumpers on that board. I don't mean to offend anyone, but it looks a little like some "no-name board" put in a case with a "name" on it 😕
What catches my eyes is the potentiometers, the tiny cooling fins, and all the jumpers on that board. I don't mean to offend anyone, but it looks a little like some "no-name board" put in a case with a "name" on it 😕
es44 said:
I would put it "rich in upgrade opportunities!"
Seriously, it looks easy to work on and improve upon. The diodes look like discrete 3A or 5A ones and not a monolithic bridge. There are some opamps there, and I hope that single in-line one has a Brown Dog adapter. The electrolytics could be replaced with Panasonic FCs on the power rails and Black Gates for signal coupling. The ammo box caps might be polyester and upgraded to polypropylene.
I would start with the preamp section first as there is the most to gain.
SimontY said:
It's just not that easy to gauge size on a photo like that. Maybe you studied it more 😉
Yes a bigger sized cap of same capacitance generally has better ripple current capacity and a few other nice properties.
I do actually use Schottky diodes in my own designs.
If the amp is only 35w then 6800uF is not too bad.
Maybe upgrading the volume pot might bring benefits.
I'll have a look this afternoon. The pot is a problem, for low levels it "schrrr" and is not so well balanced: I have to move it a lot to make both channels sounds the same!
I'll check the opamps inside, the ones for tone has no interest as I use the direct bypass, but if another I can upgrade it (some LM4562 for dual and BP627 for single, many are lying here around...).
I'll check the opamps inside, the ones for tone has no interest as I use the direct bypass, but if another I can upgrade it (some LM4562 for dual and BP627 for single, many are lying here around...).
I'm pretty sure it's not an alps pot. The pots look like 2$ types, very unstable, so that is a very good place to start 🙂
Malefoda said:
Hi,
What mosfets are used in the output stage ?
I might 'gainclone' my old Arcam alpha (not one).
Good evening fellows,
first for those who want to have a look to the service manual:
Service Manual
As you see the mosfet are SMF045. I may have benefit upgrading Z302 (4560D) and Z301 (NE5532), but I don't understand what they are here for and why these are different opamps. Maybe I'll have better results by using also two different better opamps: LM4562 and AD8620 or OPA2134, or just LM4562 for both?
Any weak point you can see elsewhere? I find strange C30/C130 shows big place on the PCB but are small, as C205/C204, the res caps, wich are 10.000u 50V on the big brother Amp Alpha 7.
Maybe the specs of the 7 should be a target, as the 7 was a higher class?
As I told you, I just want to make the cheap, efficient & easy upgrade, as the opamps wich are already my own. (from the CD63 looooong thread program 😉 ).
Thanks guys!
first for those who want to have a look to the service manual:
Service Manual
As you see the mosfet are SMF045. I may have benefit upgrading Z302 (4560D) and Z301 (NE5532), but I don't understand what they are here for and why these are different opamps. Maybe I'll have better results by using also two different better opamps: LM4562 and AD8620 or OPA2134, or just LM4562 for both?
Any weak point you can see elsewhere? I find strange C30/C130 shows big place on the PCB but are small, as C205/C204, the res caps, wich are 10.000u 50V on the big brother Amp Alpha 7.
Maybe the specs of the 7 should be a target, as the 7 was a higher class?
As I told you, I just want to make the cheap, efficient & easy upgrade, as the opamps wich are already my own. (from the CD63 looooong thread program 😉 ).
Thanks guys!
Assuming you bypass the tone controls.....:
Upgrade Z302 4560 opamp to LM4562 and also the Z305 NE5532, if you use phono. Leave Z301 alone (it adjusts the amp's DC voltage offset to 0V).
There's heaps of electrolytic capacitors in the signal path, mostly 10uf, and a pair at the amp input. Most look like they can be replaced by wire jumpers - check the test points to verify that the DC voltage is indeed 0V first. With the tone controls out of the circuit, you have one set of DC blocking caps in the phono section, one in the preamp line stage, , and one in the amp. You may want to leave one DC blocking capacitor in place, say at the amp input. Its 22uF and a 10uF, both electrolytic. You could use a Black Gate N type with (optionally) a metalized polypropylene bypass.
I'd do the signal path first, upgrade the preamp power bypass caps second, and lastly do the amp power supply.
Upgrade Z302 4560 opamp to LM4562 and also the Z305 NE5532, if you use phono. Leave Z301 alone (it adjusts the amp's DC voltage offset to 0V).
There's heaps of electrolytic capacitors in the signal path, mostly 10uf, and a pair at the amp input. Most look like they can be replaced by wire jumpers - check the test points to verify that the DC voltage is indeed 0V first. With the tone controls out of the circuit, you have one set of DC blocking caps in the phono section, one in the preamp line stage, , and one in the amp. You may want to leave one DC blocking capacitor in place, say at the amp input. Its 22uF and a 10uF, both electrolytic. You could use a Black Gate N type with (optionally) a metalized polypropylene bypass.
I'd do the signal path first, upgrade the preamp power bypass caps second, and lastly do the amp power supply.
And oh yes the pot is an ALPS one. Any gain to have on this? It's already very disturbing, have to "tune" it at low volume to get the balance...
edit: Mark, you mean bypass C803/C804? I have very few knowledge in electronics, but they seem to be in the paht of the music... thank you and others to spend some times on a stupid guy like me 😉
edit: Mark, you mean bypass C803/C804? I have very few knowledge in electronics, but they seem to be in the paht of the music... thank you and others to spend some times on a stupid guy like me 😉
Mark,
you did like me, edited your post 😉
First mine does not feature phono stage (whatever I've no vinyls to listen to unfortunately...), and I think when you talk of the 10u and 22u you talk of C10/C30... wich C30 and his bros C130 are 47u 16v on mine, 22u 63v on the bigger 7 and 10u 25v Cerafine on top 8.
I think I'll check for my left component from my CD53 upgrade and put a good Elna RJH here instead of C30 and ermove both C10/C803 and twins.
Is the question of voltage, wich make bigger caps with bigger voltage as my eyes can see, I can understand it makes a difference? Maybe this is why C30 shows different voltage according to whished benefits?
When this is done I'll tell you the result. I'm amazed how all (CD53 drives me crazy already...) can be easily upgraded...
edit: no more small caps in stock...
you did like me, edited your post 😉
First mine does not feature phono stage (whatever I've no vinyls to listen to unfortunately...), and I think when you talk of the 10u and 22u you talk of C10/C30... wich C30 and his bros C130 are 47u 16v on mine, 22u 63v on the bigger 7 and 10u 25v Cerafine on top 8.
I think I'll check for my left component from my CD53 upgrade and put a good Elna RJH here instead of C30 and ermove both C10/C803 and twins.
Is the question of voltage, wich make bigger caps with bigger voltage as my eyes can see, I can understand it makes a difference? Maybe this is why C30 shows different voltage according to whished benefits?
When this is done I'll tell you the result. I'm amazed how all (CD53 drives me crazy already...) can be easily upgraded...
edit: no more small caps in stock...
For safety, the voltage rating of these caps should be higher than voltages they see. If some bad piece of equipment is connected, that might be as high as 12v. In reality, its usually a small fraction of 1 Volt. The high voltage rating used is because it might sound better and have better specifications on paper.
C30 on the schematic is listed as a Cerafine, which is an "audio grade" capacitor. Still, one jumper can be used to replace each pair. This is the best sound. With the two sets of dc blocking caps replaced with wire and upgraded opamp, your amp could sound more open, detailed, and with deeper, tighter bass.
C30 on the schematic is listed as a Cerafine, which is an "audio grade" capacitor. Still, one jumper can be used to replace each pair. This is the best sound. With the two sets of dc blocking caps replaced with wire and upgraded opamp, your amp could sound more open, detailed, and with deeper, tighter bass.
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