Amek M2500 Build and Support Thread

[kato]

One of the 4 channels is stuffed with components already.

Not trying to make this a sales post, but I'd hate to see them go to waste.

If anyone is interested, $10 for all 4 PCBs plus shipping.
I can leave the etch resist on, or remove it with acetone prior to shipping leaving clean copper.

 

[analogguru]

Here is a real one up for sale (no, not mine):
https://www.willhaben.at/iad/kaufen-und-verkaufen/d/amek-m2500-mixer-mischpult-analogconsole-387672364/

 

[analogguru]

I would have posted pictures of the original mic-preamp-pcb if the upload-folder of this forum would not be full..... :-\

 

[jensenmann]

If the maintenance has been done carefully then this desk is a bargain.

 

[ip_dalie]

Sorry to bump an ancient thread. Someone recently PM'ed asking for the original files. They had been deleted.

Here is a new link to the DIY version of the Amek 2500 by Olaf Matthes.

It will prompt you to create a dropbox account, but I believe you can bypass that request and download without creating an account.

Hi Matthew,  its me again

What the power current you reckon to drive this 2 pres?

Thank you

Ipin

 

[kato]

I would guess .2A @ 15v would be sufficient.

 

[ip_dalie]

I would guess .2A @ 15v would be sufficient.

Thank you Matthew. 

Btw, with this design, is it ok to put the original TL072 ic's on the board?
 

 

[kato]

Thank you Matthew. 

Btw, with this design, is it ok to put the original TL072 ic's on the board?

Yes.
I could be wrong, but I don't think there are any significant changes from the original that would prevent a TL072 or TLE2072 from working fine, and probably sounding exactly the same as the more modern replacements.

 

[ip_dalie]

Yes.
I could be wrong, but I don't think there are any significant changes from the original that would prevent a TL072 or TLE2072 from working fine, and probably sounding exactly the same as the more modern replacements.

Thank you Matthew.

I've finished the soldering job for 2 boards, but haven't tested it yet, just want to make sure everything is alright 
All the ICs are TL072, hope its okay, and where is RG going? Potentiometer? (1kohm?) or Rotary gain switch?

Ipin

 

[Ricardus]

Looks good.

I've been interested in building some Amek preamps. Not sure which ones people like the best, and which ones have any PCBs available, but it is on my list.

 

[kato]

Thank you Matthew.

I've finished the soldering job for 2 boards, but haven't tested it yet, just want to make sure everything is alright 
All the ICs are TL072, hope its okay, and where is RG going? Potentiometer? (1kohm?) or Rotary gain switch?

Ipin

I used a 1k reverse log pot.
A rotary switch would probably work as well, similar to the green preamp.

 

[ip_dalie]

Looks good.

I've been interested in building some Amek preamps. Not sure which ones people like the best, and which ones have any PCBs available, but it is on my list.

Thank you Ricardus, Haha, yer I made a pair of this version too  ;D  I'll compare them tomorrow,

Ipin

 

[ip_dalie]

I used a 1k reverse log pot.
A rotary switch would probably work as well, similar to the green preamp.

Thank you Matthew! You rock  8)
I'll try it tomorrow and let you know, can't wait to compare them with my Greens and the SSLs

Ipin

 

[kato]

Thank you Matthew! You rock  8)
I'll try it tomorrow and let you know, can't wait to compare them with my Greens and the SSLs

Ipin

Check out Pier Paolo's schematic in an earlier post.

He recommends a couple 220µF caps inline with the pot, which I think the Green preamp used as well.

 

[jensenmann]

Better use 2200uF, not 220uF. Typo?

 

[ip_dalie]

Great! Thank you Guys 

Ipin

 

[ip_dalie]

Hi Guys,

After a long delay, finally I managed to do a proper test to the Pres, I put TL072s on the boards, and no sound, and I just realized, the pinout of the ICs is different. So I put OPA134 on it. It sounds great and it workes like a charm  ;D I'll post a picture when I finish racking them.

Thank you Matthew for the documents!!  ;D

Ipin

 

[Ricardus]

Do the corresponding transistors need to be gain matched in that group of 8?

 

[Matt Syson]

One of the advantages in using multiple transistors is that it reduces the need for matching and they weren'tn matched in production consoles so where do you want to put 'authenticity'?

 

[Lucas Rosso]

I'm working on these preamp too, trying the first to later do more 3. I'm testing with NE5534 and BC560

Any advise on these?