AMEK 2500 info/tips wanted

I have been asked to take a look at an AMEK 2500 that a friend is interested in, just to see how it shapes up.

Can anyone tell me if there is anything that is prone to failure or any common problems to look out for with these desks ?

- Fader reverse relays (they are mounted the wrong way, so they don't last long).

- Mic preamp capacitor (thin sounding at high gains).

- PCB edge connectors wears.

- the original "CUT" switches are not very good

Jakob E.

Thanks Jakob

- Mic preamp capacitor (thin sounding at high gains).

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Jakob, any tip on what kinda caps sound better on the 2500? Poliester?

:guinness:
Fabio

Are those the input caps or the DC blocking caps at the gain control?

The 2200uF/6V at the gain pot. Use a high-quality type here, bypassed with a small polyester.

Hi!

I'm working on a pair of Amek 2500 channels. I have layout for main board done (from Gyraf's schematic) and tested. Everything looks fine, i just have to measure gain and few other things.
A friend sent me moded version of 2500, it uses OPA 604 in place of TL072 and NE 5534. He says it sounds ok but not very good.

I have a few questions:
- Do you suggest to make original or moded version? I've seen OPA 604 in many "audiophile" applications, but not in pro audio. I'm quite sure Amek knew why they used TL and NE chips.
- Moded version is running on 24 and original on 16V. Do i gain anything from running it at higher voltage?

I know, this are very general questions and i should try the mods myself and see what comes out. But at the moment i don't have money for experiments (i got myself together and am finishing projects i should finish long long time ago , so i have to pick one version and just finish it.
If anyone have any other observations about this build i would be happy to know about them.

When i'm done i can post entire layout (phase, probably pad, fantom...) if people are interested.

Miha

Funny to see this thread pop up today, because I bought a M2500 yesterday.

I thought the reputation of this board came from the EQ and Pre. Everybody and one says it´s the best Amek ever so why mess with OPs? Besides this I´ve seen lots of EQs with TL072s which are darn good.

Only reason for higher voltage might be more headroom but neither TL072 nor NE5532/4 like that. I have no schematic right here but the circuit possibly might suffer from a different voltage than it has been designed for (as said without knowing details)

because I bought a M2500 yesterday

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You did WHAT? I thought you were looking for a small solution? And as far as I remember the M2500 is the exact opposite of a small mixer, right?

tstststs...

:grin: well, the price was just too good. And now I have a reason to find new rooms :wink:

uups..

Hi!

I have a few questions about Amek 2500:

In my build i used 1k log pot (R26 on Gyraf's schem) and response seems a bit strange. A bit, maybe i'm just too picky or my quite old pot is strange. So, should i use rev log pot? Pot is marked 1KC and i was told C means rev log...

In another old thread Gyraf suggested to use high quality C10 (2200/6V3) bypassed with a small poliester. How small it should be? I have some nice 0,1u poliesters, is this enough?

Miha

I never liked the OPA stuff. I did a lot of subjective A/B testing and found that they sounded "hi-fi" with scooped mids. They are NOT clean nor neutral in any respect. I found them harsh in circuits that were designed correctly. In circuits that are less than ideal they can sometimes make things sound better, but it's simply a byproduct of that specific combination. Stick with the original opamps and focus on proper decoupling and bulk capacitance. The 5534 needs careful and liberal decoupling or else it will sound bad.

Yeah, i don't like OPA stuff either. I didn't do a lot of tests but to me the OPA stuff i tried sounds unnatural in highs. Of course it probably depends of application...
Any thoughts about my questions? I'm ordering material for "better" version and would really like to know more.

Thanks!

The Amek 2500 was a great sounding board.
I can remember trying one for the first time in the 80's and being very impressed. I think that it made Amek's reputation.