[wushuliu]

This thread relates to modifications to the outstanding classdaudio amps discussed in the main thread in Cheap and Cheerful.

Earlier in this thread someone was asking for opinions of going with one of the linear PSU boards at connexelectronics.com over the one offered at classDaudio.com. I don't think anyone addressed this. Unfortunitely, I can find very little info about them on the website. Does anyone have an opinion about either of these modules with the SDS-254 or SDS-258? Would the combined 60,000uf capacitance of these be any sort of an upgrade?

http://connexelectronic.com/product_info.php/products_id/69?osCsid=3prbrltmu15kfebq69if854uf2

http://connexelectronic.com/product_info.php/cPath/25_45/products_id/87?osCsid=3prbrltmu15kfebq69if854uf2

wushuliu, what size of par-metal case would you be considering? 12x12x4 or 12x16x4?

I went w/ the 12124 Gold. Their customer service is great.

The connex have a good rep on diyaudio (mostly for tripath amps). As to whether it constitutes an upgrade, you'll have to let us know... 

To muddy the waters even further, 41hz. com has a neat looking PS:

http://www.41hz.com/shop/item.asp?catid=11&itemid=692

More expensive, but they use high quality parts.

[lo_tse]

Earlier in this thread someone was asking for opinions of going with one of the linear PSU boards at connexelectronics.com over the one offered at classDaudio.com. I don't think anyone addressed this. Unfortunitely, I can find very little info about them on the website. Does anyone have an opinion about either of these modules with the SDS-254 or SDS-258? Would the combined 60,000uf capacitance of these be any sort of an upgrade?

http://connexelectronic.com/product_info.php/products_id/69?osCsid=3prbrltmu15kfebq69if854uf2

http://connexelectronic.com/product_info.php/cPath/25_45/products_id/87?osCsid=3prbrltmu15kfebq69if854uf2

wushuliu, what size of par-metal case would you be considering? 12x12x4 or 12x16x4?

I was looking at these PS too.  However, each of these PS has a specified voltage (100 V and 80 V) - does it mean they only work with that particular voltage (as supplied by the secondaries of the transformer) ?  According to the info listed at the ClassDaudio website, the CDA-254 works best with a 50 V PS and the CDA-258 can work with a supply upto 75 V (I think).  So these two Connexelectronic PS mentioned here seem inappropriate??  Any opinions guys??

lo_tse

[wushuliu]

I was looking at these PS too.  However, each of these PS has a specified voltage (100 V and 80 V) - does it mean they only work with that particular voltage (as supplied by the secondaries of the transformer) ?  According to the info listed at the ClassDaudio website, the CDA-254 works best with a 50 V PS and the CDA-258 can work with a supply upto 75 V (I think).  So these two Connexelectronic PS mentioned here seem inappropriate??  Any opinions guys??

lo_tse

?

The cap voltages represent the maximum recommended supplied for their use. I think you're mixing up the transformer specs w/ the cap ratings. In other words, the 80v connex boards will work for either amp (though it may be safer to get the 100v for the higher voltage amps).

[cynan]

I would think that 80V capacitors should do the trick. With the higher power ClassDAudio amp (XXX-258) kits, Tom seems to bundle Antek transformers with 45V secondaries. That means you should see about 64V output, giving a decent margin with 80V caps. Plus, with decent quality caps, the voltage rating normally represents nominal voltage. For example, a good quality 80V cap should handle 100V peaks.

I asked Tom why he doesn't bundle tranformers with 50V secondaries (giving V output of about 71V) with the SDS-258 and he said that though the 258 can take up to 75V, it would run hot. I guess he feels this would limit the lifetime of the product? I wonder if 70V would be OK with some kind of active cooling (ie a small/quiet PC fan blowing down onto the heatsink).

Anyone have XXX-258 boards running voltages higher than 65V?

Would there be any benefit in going with a tranformer that can provide 6 or 7 amps on the main rails instead of around 5? (ie, 600VA or larger with the XXX-258?)

Thanks in advance!
 

[Mariusz]

Wushu

Thanks and enjoy the tech talk (I know I will)

Cheers
Mariusz

[wushuliu]

Wushu
feel free to edit your post accordingly since it is the FIRST post after the split.

Thanks and enjoy the tech talk (I know I will)

Cheers
Mariusz

k

thanks Mariusz

[lo_tse]

?

The cap voltages represent the maximum recommended supplied for their use. I think you're mixing up the transformer specs w/ the cap ratings. In other words, the 80v connex boards will work for either amp (though it may be safer to get the 100v for the higher voltage amps).

Wushu,

Thanks for clearing that up.  In the Connexelectronic website, there are no mention on the number(s) of output for the PS.  The ClassDaudio amps requires 2 supply rails (there are 2 secondaries in power transformer recommended by Tom).  Any ideas?

I am thinking of suggesting to Tom to sell a "hot-rod" version of the PS using the Panasonics caps, higher rating rectifier and resistors so I can buy everything from him without having to source from different places.  It may not fly though.

Lo_tse

[jtwrace]

I'm sure if you send the parts to Tom, he'll build you one with them.  It doesn't cost him anymore money.  He just might not warranty it.

It's worth asking.

[cynan]

In the Connexelectronic website, there are no mention on the number(s) of output for the PS.  The ClassDaudio amps requires 2 supply rails (there are 2 secondaries in power transformer recommended by Tom).  Any ideas?

I am thinking of suggesting to Tom to sell a "hot-rod" version of the PS using the Panasonics caps, higher rating rectifier and resistors so I can buy everything from him without having to source from different places.  It may not fly though.

I'm pretty sure that the linear power modules at Connexelectronic accept dual AC secondaries from the transformer. I remember reading in one of the manuals for the amplifiers on Connexelectronic where they refer to using a torroidal transformer with dual main rails. Plus, I think it is pretty standard for transformers above a certain size to have 2 secondary rails?

But I have to say, I'm pretty dissapointed with the product information on the Connexelectronic site. (ClassDaudio isn't perfect in this regard either but they are much better). I don't know how Connexelectronic expect to sell some of the stuff with the condition of the website. For some of the products, the descriptions are completely missing due to web design issues (ie, some of the linear power modules). This is sort of ironic, because if you can find one of their product manuals, they are quite comprehensive...

I think you should ask Tom about building a power module with higher quality parts (ie, Panasonic caps) and see what his thoughts are. He obviously thinks that his designs are good enough, but it can't hurt to see what he thinks about it.

[wushuliu]

I'm pretty sure that the linear power modules at Connexelectronic accept dual AC secondaries from the transformer. I remember reading in one of the manuals for the amplifiers on Connexelectronic where they refer to using a torroidal transformer with dual main rails. Plus, I think it is pretty standard for transformers above a certain size to have 2 secondary rails?

But I have to say, I'm pretty dissapointed with the product information on the Connexelectronic site. (ClassDaudio isn't perfect in this regard either but they are much better). I don't know how Connexelectronic expect to sell some of the stuff with the condition of the website. For some of the products, the descriptions are completely missing due to web design issues (ie, some of the linear power modules). This is sort of ironic, because if you can find one of their product manuals, they are quite comprehensive...

I think you should ask Tom about building a power module with higher quality parts (ie, Panasonic caps) and see what his thoughts are. He obviously thinks that his designs are good enough, but it can't hurt to see what he thinks about it.

Yes, the connex boards that were linked should accept dual secondaries (edit: dual w/ center tap anyway). As for Tom and upgrades, I think the point that was made in the main thread by dewardh and others is that ideally more than just the caps need to be upgraded - other elements like the rectifier, bypass/snubber caps, etc. in the overall PS design may offer improvements. The connex incorporates some of these components. I'm sure cost has a lot to do w/ Tom's design of the PS. Everything adds up.

Also Cristi from Connex is very active on diyaudio in the Vendor's Forum. So if you have questions about his products that's a good place to go. He's very responsive.

Here is a link to an article on linear PS design. You can see the classd design falls in the first tier. However, this article does not deal with Class D/T amps.

http://www.tnt-audio.com/clinica/ssps1_e.html

I'm still very new to PS side of things.

[wushuliu]

So I went and ordered the 80v Connex PS board... 

[Nick77]

Wushuliu what benifits will this ps offer over Toms?

I am still thinking about replaceing the bridge on my supply with a higher current version but undecided about regular silicon or fast recovery at 10x price.

[wushuliu]

Wushuliu what benifits will this ps offer over Toms?

I am still thinking about replaceing the bridge on my supply with a higher current version but undecided about regular silicon or fast recovery at 10x price.

Won't know until I hook it up. May not offer any benefits at all, but the connex design as i said includes bypass caps, higher capacitance, and fast rectifiers (i think, hard to tell from the photos). Whether this translates to audible improvement remains to be seen, er, heard.

EDIT:

Here is a schematic for the Connex:

[cynan]

So I went and ordered the 80v Connex PS board... 

Good Man! Now to see if I can wait for your opinion on it before I order something 

Thanks for posting the schematic as well. I suppose you don't know what brand of parts are used.  You will have to let us know when you get it!

At any rate, it looks like the AC in is identical to what's on Tom's board, so this means that it definitely accepts dual secondaries.

Any thoughts about the use of dual fuses at the AC in? (I guess this also means you don't need a fuse at the IEC socket?)

[wushuliu]

I know this is slightly OT but I just want to put a big fat recommendation for the 193L Choke-as-power conditioner Diy tweak that Alan Maher whipped up a few years ago.

If you don't know what it is. It's just a 193L filter choke that you can get from PE or Radio Daze

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=122-380%20%20%20%20%20%20%20%20&FTR=193L&CFID=28024228&CFTOKEN=42159699

You put one wire into the Line of an AC plug (that you can get from HD or anywher), the other into the neutral... and plug in the wall. That's it.

As I understand it, it's something like a really poor man's Richard Gray Power Conditioner. There are some posts on AC about it going back a long way, and several years of steady testimony on audioasylum for those who wish to see if it's on the up and up. What's reassuring is that if you're TV is in the same circuit you'll see the effect it's having and your audio will go through very obvious roller coaster as it settles in. And yes, it's safe, and will not damage your stuff.

When I plugged one of the several I already had directly next to my classd amp (insert poetic verbiage here)! And the best thing is, it's right there in your face. Nothing vague about effect it has. I rank it far above upgrading the PS caps or wire or... It's $50 well spent.

Of course, be careful as always w/ anything AC related.

Anyhoos, been meaning to mention this for a while. It rocks the bells.

[lo_tse]

So I went and ordered the 80v Connex PS board... 

Wushu,

Way to go!  You are a man of great adventurous spirit!! Let us know how it work out!!  Thanks for posting the schematics!  Yup, there are two output rails - it will fit our amps. 

I guess one way to avoid the amp to work at temperature within the limit originally designed is to find a transformer that provide higher current (as supported the bigger caps) but with output secondary voltages recommended by Tom??

Since there are two fuses on the PS board already, I am sure that one can omit the AC line-in fuse since the amp and PS borad are downstream of the fuses.  But then again, the transformer would be on it own in case of a huge surge.

May be I missed it, would you have a link (not the PE one) to the 193L filter choke? I would like to learn more about this "gadget" and how it works.  Thanks!

Hey, this ClassDaudio board is getting more and more interesting!!

Lo_tse

[wushuliu]

Wushu,

Way to go!  You are a man of great adventurous spirit!! Let us know how it work out!!  Thanks for posting the schematics!  Yup, there are two output rails - it will fit our amps. 

I guess one way to avoid the amp to work at temperature within the limit originally designed is to find a transformer that provide higher current (as supported the bigger caps) but with output secondary voltages recommended by Tom??



Since there are two fuses on the PS board already, I am sure that one can omit the AC line-in fuse since the amp and PS borad are downstream of the fuses.  But then again, the transformer would be on it own in case of a huge surge.

May be I missed it, would you have a link (not the PE one) to the 193L filter choke? I would like to learn more about this "gadget" and how it works.  Thanks!

Hey, this ClassDaudio board is getting more and more interesting!!

Lo_tse

Here's an old link discussing the concept and how it came about.:

http://www.audiocircle.com/index.php?topic=10310.0

Can't find an exact Alan Maher explanation for you because there are too many posts about it here and audioasylum to weed through, but here's one that should do:

http://db.audioasylum.com/cgi/m.mpl?forum=tweaks&n=144960&highlight=193l+filter&r=

[lo_tse]

Here's an old link discussing the concept and how it came about.:

http://www.audiocircle.com/index.php?topic=10310.0

Can't find an exact Alan Maher explanation for you because there are too many posts about it here and audioasylum to weed through, but here's one that should do:

http://db.audioasylum.com/cgi/m.mpl?forum=tweaks&n=144960&highlight=193l+filter&r=

Wushu,

Thanks for the links!

Lo_tse

[jtsnead]

Won't know until I hook it up. May not offer any benefits at all, but the connex design as i said includes bypass caps, higher capacitance, and fast rectifiers (i think, hard to tell from the photos). Whether this translates to audible improvement remains to be seen, er, heard.

EDIT:

Here is a schematic for the Connex:

Please post a pic of how you wired this bosrd up.
I am odering one for my SDS254

Thanks

[Nick77]

I cant wait to hear your results with this PS since you already have an upgraded one. If its as good or better than it will be a great option for newbies when buying their amp instead of just getting the standard PS.

Do you know the capasitance and caps used?