[Cheeba-Fi]

Hello All,

Wanted to show the CHA47 I just finished. Nothing major, just the obligatory post with pics (in this and the following posts). Thanks to all who contribute so much knowledge to this forum (I'm not going to list them, because I would hate to miss someone and everyone knows already).

Namastay,
Cheeba-Fi

 

[Cheeba-Fi]

Pic #2

 

[eric343]

Very nice! I like the metal faceplate...

here's the images if you're too lazy to go linkclicking:

 

[andrzejpw]

congrats! Very nice amp.

 

[blip]

Very nice amp... What kind of enclosure is that? I like it.

 

[Cheeba-Fi]

Thanks for the replies,

blip, The case is a standard Serpac H-67, AC. I had not seen anyone use this case before I tried it. The H-67 and H-67, 9V seem to be used commonly. The only difference in this case and the H-67 9V is that it has the access panel (hence AC) on the bottom without the built in 9V slot, so you can fit 2 9V's in the case with a hansen board. Here are the specs http://www.serpac.com/pdf/h-67ac.pdf. All said it works very well.

eric343, Thanks for assisting with the pics, I have more but got tired of hacking them down to attachment size. The "metal" face plate is not really metal. It is aluminum tape that is applied to the regular plastic insert. It was an afterthought, but I think it looks sharp. If I were going to do it again I would apply it to the smooth side of the plastic rather than the grain side, but I had already drilled the holes and didn't want to re-run my wires. I picked the tape up at Wal-Mart in the auto dept. because it was handy (I'm sure better (thicker) metal tape can be found elsewhere). It has yet to prove how durable it will be, but hey, I can always pull the old off and put a new piece on.

A few tips if you are going to try this: Make sure that the grain of the tape is running in the direction you want before application. Put the tape face down on the table and then apply the plastic face plate to the tape starting at one edge and "hinge" it down into contact with the tape. Flip the piece over and rub a folded up paper towel over the aluminum surface to make sure everything is in good contact. Use an X-acto knife with new blade to cut open the pre drilled holes. I cut it in pie sections and folded it back. It was also necessary to trim all of the excess material from around the LED. Just be slow and deliberate with the trimming and everything should end up perfect.

Namastay,
Cheeba-Fi

 

[scottder]

Bumping this thread up, what is the difference between building a straight CMoy and CHA47, i just ordered some Hansen boards (before they disappear forever).

 

[scottder]

BTW, what color is that LED and what opamp are you using?

 

[Budgie]

That amp looks really good with the Grado's. That aluminum front panel makes a nice match to he aluminum in the cans. Tasteful.

Scottder- The amp is here-
http://headwize2.powerpill.org/proje...heared_prj.htm

 

[scottder]

What are the advantages/difference of a CHA47 vs a Cmoy?

 

[tangent]

Quote:

What are the advantages/difference of a CHA47 vs a Cmoy?

Just curious, but how many more hours are you going to wait for an answer before you break down and do a search in the archives?

 

[scottder]

sorry, point taken

 

[Cheeba-Fi]

scottder,

The LED is green and I'm using Burr Brown OPA 2134's the gain is 5. I think you will find the best explanations on the differences between a CMOY and CHA47 in the archives here and at Headwize.
Or just try this link: http://headwize2.powerpill.org/proje...heared_prj.htm
By the way I see you are using HD280 Pro's, a CHA47 will make them sing. My train commuting rig is a Sharp MS-MD722->CHA47->HD280's and it always puts a smile on my face (what stop was that??? I can't even hear the conductor's announcements).

An update for everyone else,
The aluminum tape is proving to be fairly durable. It has a few depressions in it now but still looks good. I think if I had used the smooth surface of the plastic and burnished the aluminum with a true burnisher (smooth glassy stone) the depressions would have been less likely to occur. One caveat, I wrap the amp in a bandana when not in use (I haven't had time to make a bag for it) so I guess I should say "carefully" durable for the faceplate.

If anyone wants to see images of the guts, etc. let me know and I will email them to you. I'm not inclined to try and post them since I have to hack them way down and they would look crappy.

Thanks for looking and the comments.

Namastay,
Cheeba-Fi

 

[scottder]

I bought several of the Hansen boards, so I may build a straight Cmoy with one then try a CHA47 with the other. We shall see.

PS I would love to see the inside of your amp

 

[{-_-}]

How can I do something like that ?