First tests with my 5ch GC

[Mika]

Hi,

I have made some first listening tests with my 5 channel gainclone. LM3875T is in noninverting mode, and PCB uses mostly SMD components to make shortest signal path. Also signal side has own ground to star grounding point.

In first tests, there is no any audible mains hum. Also i cant hear any noise. I think that my Yamaha integrated amplifier is more noisy than GC. I have to make some performance measurements when i got whole amplifier ready. Now i have use only MAIN channels.

And sound: First time i can hear difference between amplifiers. GC makes much better stereo image, especially now i can hear that music has third dimension, depth (i hope u understand what i mean . Only bad thing is that in lower frequencies hasnt power so much than my Yamaha. -3dB point is about 7Hz, so i think bandwith isnt problem for that. Mids and highs i cant hear any big difference.

I will use all 5 channels in my home theater system. Im using two separate MAIN channels for listening music. I have two 250VA transformers, one for MAIN-channels and other to three for surround channels.

[JCoffey]

PURTY.....
I'm planning on something similar for 5 LM1875's for a PC 5 channel amp...

[Eccu]

Very nice indeed....



Oikein poika! Myit talon ja ostit viinaa!

[Doovieman]

Nice work! That's sweet looking...what CAD softare are you using? Thanks,

Doovieman

[jean-paul]

Let's just ask if Mika is willing to share his PCB design..... The Straight and Honest approach if you ask me.

Very good looking PCB !!

[jleaman]

I already did no reply though. i want to do one of his boards for my friend. Hope i can either buy a board or get a pcb layout.

[Doovieman]

Originally posted by jean-paul
Let's just ask if Mika is willing to share his PCB design..... The Straight and Honest approach if you ask me.

Very good looking PCB !!

Actually, I just want to know what CAD software he's using...but if you want his PCB artwork, you can go ahead and ask...

[Mika]

Im using quite old version of Protel software, ISIS for schematics and ARES for PCB. I will made some little improvements to board, some changes to trace widths and signal path grounding. Those changes are just finishing, not any big changes.

If anyone wants, i can send protel files via email. Also i can make website, where you can find schematic, PCB layout and parts list as image if you dont have protel software. Website takes few days to make.
Some information: PCB size is 160x100mm. All SMD components uses 0805 packages with littlebit larger pads to make solder easier. Electrolytic capasitors uses 16mm can (im using 1000uF/50V) .

This amplifier is part of a bigger project, where i build whole home theater system. It uses this amplifier and now im building pre-amplifier with 6 channel analog input. Preamplifier consists 3xCS3310 digital potentiometer (not PGA2310 because i cant get those), Hitachi LCD, powersupply and PIC16F877 microcontroller. Software has little menu, where user can change all six speakers levels +/-8dB. Of course software also adjust all levels at same time as volume

[jleaman]

Mika i'm glad to hear that you will share. If you need the web-space let me know i got lots and a static ip. : O ) Im interested in all your ideas.

[Dark Shadow]

Originally posted by Mika

If anyone wants, i can send protel files via email. Also i can make website, where you can find schematic, PCB layout and parts list as image if you dont have protel software. Website takes few days to make.

I would not mind if you send me this files via email =) planning to build a 5ch for my computer, it will save me some time =)