CJ Solid State Amp Recommendations

[Timo62]

I might just give the MF2275 a try. I feel like it would be a good candidate for a back up amp on hot days. It should do fine with low to medium level volume listening. Plus , I have a chance to buy one for a very reasonable price.

[jahatl513]

Hello, The MF2500A is as solid a rock as needed. I too have a Classic 120SE and the MF2500A simply handles any speaker load and is pure CJ sound; forget the 2550SE and yes take a Premier 350 when you can but MF2500A is my recommendation.

[AnotherJohnson]

forget the 2550SE and yes take a Premier 350 when you can but MF2500A is my recommendation.

Is there a reason you would dismiss the MF2550SE?

Mine has been incredible and is my favorite solid state amp of all time. With some speakers, like the ML ESL Hybrids, I think it is a better match than my pair of LP275Ms.

Just curious to know what it has done in your system to recommend that it be forgotten.

[Big Dog RJ]

G'day Jahat,

Certainly understand your point of view and preference for the MF2500A. Infact the MF series of CJ's amplifiers are very fine musical instruments. You really can't fault any of them. Then comes along the Prem350 and its a rare beast! Brute force no doubt but it had bi-polar transistors in the output stage if I'm correct... and to me this was "hard hitting."

Since I'm very passionate about panels and full range stats, when I tried out the Prem350A with my ACT2, it was definitely overpowering. It has unlimited amount of current drive and power, as I've mentioned in one of my previous posts, this thing can launch the next shuttle for NASA if required... it's that powerful!

Partnered with the ACT2 it was a formidable force, nothing could hardly match that combination in that particular price range. This kind of raw power and drive, I've experienced with Boulder amplifiers, Momentums, Relentless, Pass Labs XS series, Hercules, CH Precision, Threshold and so on, these are the big boys. Plenty of power on tap and plenty of dollars on hand... we're talking 100grand over in amplification. This is the level the Prem350A is at.

However, with a slightly less gain on the linestage, you can tame the sudden burst / force of energy the Prem350A is capable of. Only a handful know this, and have tried it but have not posted their recommendations. Probably because they're too busy enjoying that explosive energy of the Prem350A.

This amplifier was then discontinued and came along the MF2550SE. Aaaah! Now that was like walking into a cool room on a very hot day. It was a perfect balance of both power, current drive, reactive load handling and delivered a fine balance of realism. When called for, it can produce some serious power and yet have all the subtle details without being overblown. This particular trait is thanks to the cleaver design of having both bi-polar and Mosfets used in conjunction. At the end of the day, Mosfets will always have that signature sound closer to tubes but with ample more drive factor involved.

It also takes an awful amount of time in order for the MF2550SE to really kick in. Once it reaches its pinnacle, it's an extraordinary opportunity to experience it, and the way it delivers the whole presentation, provided your speakers are upto the task!

Although I did enjoy my time with the Prem350A and for what it was capable of, that kind of power and level of brute force was not really required to drive the ribbon panels and stats that I was using at the time. Hence, my preference and overall favourite CJ SS amplifier is the MF2550SE, and I'll probably end up with one, once I get too old to bias and maintain tubes...

That's just my personal opinion and preference. I'm sure you've got your facts and reasons but I certainly wouldn't dismiss the MF2550SE. As I've stated earlier, it's no ordinary amplifier.

Cheers, RJ

[AnotherJohnson]

There is a NOS MF2550 on eBay right now for less than $2800 plus shipping.

I called CJ to see if they could upgrade it to the SE if I bought it and sent it in. Sadly, they cannot due to lack of all the specific precision resistors.

I expect that the non SE version is a killer amp ... but I want one to pair with my SE model, so I’m going to pass.

[Big Dog RJ]

$2800... jeeze, that low?

I would be very sceptical buying something like that on Ebay...

OTOH perhaps once you do get the unit, sending it off to CJ HQ to conduct a full service/check, would be worth it. I guess they would be able to confirm the serial number as well, which will authenticate its origin. In that case all should be well.

Anyone looking for a superb SS powerhouse with power and finesse, should consider this amplifier. The standard version is very good, its performance is truly top notch. The SE version has a few extra goodies that gives it a whole other dimension but that's something that is expected from CJ's SE versions.

All the best to the rightful owner or the new owner to be... As I've stated before, the MF2550SE is not just an ordinary amplifier.
Cheers, RJ

[AnotherJohnson]

$2800... jeeze, that low?

I would be very sceptical buying something like that on Ebay...

OTOH perhaps once you do get the unit, sending it off to CJ HQ to conduct a full service/check, would be worth it. I guess they would be able to confirm the serial number as well, which will authenticate its origin. In that case all should be well.

Anyone looking for a superb SS powerhouse with power and finesse, should consider this amplifier.

The offer is from a reliable supplier and it is in sealed factory packaging.

I’d just buy it and play it if it were me. Of course it’s easier for someone in the US to deal with a US based seller. I would be hesitant to buy if the offer were by a seller in another country.

I have bought from Hong Kong, Europe, Canada, and even California () in the past, but there’s always that feeling of uncertainty until the item shows up and proves good.

The only time I ever got screwed on eBay was back in 2006 when I needed a rare Whitworth wrench to complete my 1970 Royal Enfield Interceptor’s tool kit. I found one with a seller “down under” for a modest price with modest shipping charge. Of course it’s easy to undercharge if you have no intention of delivering the goods. I never saw the wrench .

[Rwclay]

Can someone describe the design goals of the MF2100 and where their use is best suited?

[Big Dog RJ]

MF2100, nice one!

This was my very first SS amplifier from CJ, it was a revelation being used to Musical Fidelity, NAD, Arcam, Audio Lab, Parasound, Bryston, and a host of other useless ones...
The CJ MF2100 was in a class of its own. I would say probably in the league of Krell, Sumo, Adcom, Plinius and Pass Labs at the time. These were considered the big boys / top dogs... and then we ordered in the MF2300 and boy did that drive virtually anything!

The MF series amplifiers are all based on Mosfet output stages and have that certain warmth to the sound after it gets going. It was rated at 100w/ch and also came equipped with a clipping circuit, LEDs on the front panel just in case the amplifier was over-driven. We first used it on all of our Paradigm, Energy and Sonus Faber speakers we sold at the time. These speakers were fairly easy to drive, with a benign load of 6ohms nominal, around 88/90dB sensitivity.

For lager panels, such as the Maggie's and Apogee's, we used either the MF2200 or the MF2300 or CJ's larger premier series monoblocks Prem12's and Prem8A's.
Mostly matched with the PFR preamp at the time and also with the original Art preamp used in our personal reference system, all of these combinations were top of class SOTA systems.

The MF2100 was a wonderful amplifier, given the right load and a equally high quality preamp to match it, it's a great combination to the entry level of SOTA. I really enjoyed my time with it, and at the moment I'm using their latest SS design the MF2550SE to drive CLX's but sadly the MF series amplifiers are discontinued. No more SS offered by CJ. Unfortunate.

Cheers, RJ

[Big Dog RJ]

Hey Rwclay,

Was just wondering, if by any chance you had the means of saving up a bit or coughing out the extra spend on a slightly better amplifier than the previous MF series?

When I say "slightly better " that is a serious understatement! It is actually supremely better, and far superior in every sense of the term power amplifier, and that amplifier I'm referring to is none other than the MF2550SE.

If you can get hold of one, this would be my highest recommendation. There are ones available for very reasonable pricing, it's just a matter of looking around.

I've got one right in front of me and I'm using it to drive my CLX's, it's superb!

However, that's only temporary until one of the monoblocks gets attended to and comes back...
Cheers, RJ