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AudioSector-chip amp kits, dacs, chassis

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Thanks for your replies.
 

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wire guage

I have only built one, so I followed your advice and benefited from your research. I used bare copper 12 on the OG (had to sand it down to get it into the pcb) 18 to the speaker (copper) and 3 strands of 30 guage pure silver on the input hard wired to your DAC. The sound is very clean and alive.
 
Hi Peter.

Would you mind taking a few moments to check out the internal arrangement of my 'Budget Patek' please?

I couldn't afford Black Gates so using 4 x 100uF Elna Silmics at the chips, and 300VA 2 x 25V transformer in separate PSU enclosure, with one of your rectifier boards, and two Black Gate 1000uF / 50v caps.

I noticed in an earlier post that the speaker grounds should go to that point marked on the circuit board. Mine are currently on the copper cross bar - is this OK or would I get slightly better results using the board point instead?

Please note that the current build also contains an 4mm thick copper heatsink on the bottom of the chassis for improved heatsinking.

Many thanks.

- John
 

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Thanks Peter - reason I asked is that I get a very faint hum from the speakers, though admittedly that's with my head practically INSIDE it haha!

Being a perfectionist I'd like to get rid of the hum altogether. I'm thinking perhaps I need a bit more capacitance that 2 x 1000uF on the rectifier boards. I did try just using them without the Black Gates and just the 100uF's on the amp boards but I got alot louder hum then.

I'll try 2200uF 50V Panasonic FC's and see if that helps.

- John
 

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Hi Audio1st!

Well the whole groundplane is one big rectangle of copper, so it's not really two earth connections at all. Basically what Peter did with his Patek was to drill slightly into the Rz areas on both boards and join them together with a piece of copper.

I didn't want to risk damaging my board by drilling so instead I 'extended' the ground-plane area of both boards by attaching copper wire to the PG+ amd PG- areas of each board as an anchor, then join those together with a single piece of wire, which is the star earth point.

I have a feeling it may be a lack of capacitance instead when used with my speakers - as an experiment I took out the 1000uF Black Gates (I need to use those for the JVC Shigaclone at any rate ;) ) and the hum level really increased. I have just received some 2200uF Panny FCs so will try those on the rectifier board and see what the hum level is like then.

Cheers,

- John
 
johnm said:
Yes, but as I said it is extremely low level. Your ear really does need to be right next to the speaker to hear it at all.

I think perhaps I'm just being over-analytical ;)


Hi John,

Nice setup...;)

Mine is using LM3875TF with a little bit different arrangement. I let the secondary side of the transformer all the way to the amp floated from the earth ground and chassis. And connect the separated power supply chassis and amp chassis together thru 10R to earth ground, this is for the safety reason.

I'm not saying this is the reason but mine is dead silence...


Joshua
 
I didn't notice that before, but those "copper wires to the PG+ and PG-" might actually do something with regards to hum.

If you don't want to drill more holes, why not connecting OG points on both boards with copper wire instead? That's what I did in Patek Integrated:

An externally hosted image should be here but it was not working when we last tested it.


The capacitance should not be a problem:with 100uF only you will get hum, and it's normal. With 1000uF the amp should be quiet.
 
Hum

The amp as wired seems to be fundamentally wired like so many others. Mine is dead quiet. With your ear right on the speaker and the volume turned up it is SILENT.

Ok, this may be right off base, but could you have a problem with a power cord crossing speaker wires? I have a Denon system in a book shelf with its crappy power cord running through the same 2" hole in the shelf as some unshielded speaker cables. With fairly sensitive Totem speakers I get the similar level of hum as you describe. Just a thought...
 
johnm said:
Thanks Peter - reason I asked is that I get a very faint hum from the speakers, though admittedly that's with my head practically INSIDE it haha!

Being a perfectionist I'd like to get rid of the hum altogether. I'm thinking perhaps I need a bit more capacitance that 2 x 1000uF on the rectifier boards. I did try just using them without the Black Gates and just the 100uF's on the amp boards but I got alot louder hum then.

I'll try 2200uF 50V Panasonic FC's and see if that helps.

- John


I had hum issues with separate power supply (like yours) and tried every possible trick (different power supply cables, power supplies, grounding, zobel, bypassing, shielding etc. etc.). I didn't get rid of hum and buzzes until I put everything in the same enclosure. The funny thing is that it was the only device that I have ever had problems like this and buzzing only occurred in my listening room (I even tried unplugging all other electrical devices and taking the electricity from down strais with an extention cord.) The buzzing changed when I moved the speaker cables so they were acting as some kind of antenna. Strange...

Here's a few photos of the humming amp.
http://www.dvdplaza.fi/galleria/showphoto.php/photo/7205/cat/500/ppuser/3104
 
I'm sure it is something simple like that - it is a bit of a birds nest of wires around the back of my system at present so I'll start with the simple things first. I don't really want to de-solder the module if I can help it.

At the end of the day it's not a biggie anyway as at any normal listening distance it's totally inaudible.

Diar - love your work on those 'mini pods' - awsome!
 
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