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Any way to "improve" a Conrad Johnson MF 2500

I recently purchased a 10 year old CJ MF2500 amplifier. It is in perfect condition and it sounds excellent, but I noticed a hum coming from my speakers when it is turned on. It got me thinking, since there is no way to upgrade the power cord, if there was a way to "refurbish" or update the amp. I don't know if that is something normal for a solid state amp, but it's sounds so good and is in such good shape that I thought I would see what the rest of you thought. It would be nice to see it work for another ten years.
jeffatus
wolf_garcia
6,734 posts
 
I'm seriously anti hum...I've been a serial "ground floater" for years (including pro audio live sound...although with electric bands the musicians may be mildly electrocuted) and even found a NOS "PS Audio Humbuster III" which really knocks out mechanical transformer hum.
czbbcl's avatar
czbbcl
1,752 posts
 
I was using Thiel 3.6's at the time along with a premier 16lsII pre-amp. The amp became more detailed and faster while retaining the typical cj 2500 sound. It did require about 20-25 hours of burn in. The non A version smoothed over the details of the music seemingly masking it. I like to hear everything in the performance something my current system does very well(Cary SLI-80F1 / Focal Be monitors).

In the end it depends on what you are trying to improve or what you don't like about the amp.
czbbcl's avatar
czbbcl
1,752 posts
 
Is the hum coming from the speakers or the amp? The transformer in the 2500 does have a propensity to hum.If you placed the stone on top of the amp it is probably dampening the cover which in certain circumstances can amplify the hum.

Chuck
steveaudio
331 posts
 
I'm late to this thread, but own both an MF 2500A, & a MF2250 ("non-A"). No hums with either. They're both very musical-sounding amps. I can't tell that the MF2500A sounds "better" than the non-A MF2250, except for the increase in power. And as I recall it's several hundred $$ for the upgrade....
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47ghibli
29 posts
 

I really enjoy my CJ MF2250A and it has no hum or noise.  Has anyone compared 

this amp or the MF2500A to the later MF2275SE / MF2550SE?

 

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