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Review: Forte Model 4a Amplifier

Category: Amplifiers

The Forte Model 4a is clearly a gotta have amplifier. It is 50 Watts RMS per side in Pure Class A configuration.

Forte was the sister line to Threshold and with that being said much of the Threshold technology found it's way into the Forte product line. Such as the Forte 4a with its IGBT technology,which Threshold used in its T series of Power Amps.

The Forte 4a may only be 50 Watts per side,but what a glorious 50 per side it is. That is into 8 0hms,into 4 ohms it is 100 per side. During it's heyday the Forte 4a was compared against the Levinson 23.5,the VTL 225w, Muse Model 100 and other high end contenders of the day. In particular Corey Greenbery of Stereophile was more than duly impressed(Vol 15 No.11) as was Robert Hartley(Vol.16 No.7)

What was so impressive about this amp.,was its ability to deliver the music and without the slightest hint of strain. Always sounded much more powerful than the 50 per side it stated.

This amp clearly delivers the music with a transparency and detail that is hard to imagine unless you have heard it. Being Pure Class A the Forte has a sonic signature,that is agile,sweet and delicate,without a trace of the usual solid state forwardness,grain and glare were totally absent. Handles complex musical passages with a delicacy not often heard. No doubt the Forte 4a has in my opinion a damn near perfect balance of liquidity and resolution.

I listen to mostly Contemporary Rock N Roll,Jazz and Classical. This amp.,in short is just a dream to listen to. It's ability to retrieve the audio signal and pass it through to the speakers is very special indeed.

Being the jaded audiophile I am it is very hard to impress me with anything.Been in this hobby since 1957 and now 59,have just about heard and seen it all. The Forte Model 4a duly impresses. I was totally surprised by it's performance.

When new this amp had a retail of $1,790.00.They can be had in the secondary for about $400.00 to $600.00. Trust me,these prices on the Forte Model 4a wont stay this low for long. Once the word gets out on this amp.,the used prices will start moving up quite quickly. So if you have the need for a Pure Class A amp.,at what I now consider a giveaway price. Get one soon. At this point in time the Forte Model 4a is an outright steal at todays secondary market prices.

Make no mistake this amp.,can compete with any Pure Class A amp out there today.Like any Class A amp.,it runs hot and will need plenty of ventiliation. In my opinion it just doesn't get much better than this.

The difference between the Model 4 and Model 4a, is that the 4a has balanced inputs. Sonic signature is the same.

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Similar products
Threshold,Spectral,Levinson,Citation,Sumo,etc

ferrari
99golf
6 posts
 
Like most things in life you pays your money and takes your chances. After reading this review and the follow up posts as well as further research decided to take the plunge. Trying to find a Model 4a was not as easy as I had thought, wanted a very pristine example with box manual and all. After a few months was able to locate what I was looking for.

So how do I like it? I just don't have the vocabulary to express my pleasure in owning this amp. All I have read is true and then some. I have heard things in my recordings I just did not knew existed. Much to my wifes displeasure I have to keep prying myself out of my listening room. In the 4 months I have had it, I think I played every CD and vinyl LP I own. This replaces the Spectral DMA 50 that finally gave up the ghost. The Spectral was damn good, but the Forte 4a puts it to shame. In the interim while I was finding the 4a was using my friends Levinson ML 11. Very good amp and tried to talk him into letting me buy the Levinson, very glad he did not take me up on it. The Forte 4a is just liquid what sonics this produces. Now I have an excuse to have the Klyne SK5A pre amp updated.

I think to do better than the 4a I will have to spend a great deal for marginal increase in sonics.

If you need a very good Class A power amp, get one of these and like all else be sure of whom you get it from. It pays to be careful.
marktime
3 posts
 
FYI the IGBT transistors used in these have substitutions of the same type of device and should work fine. IE the
2SC3281/2SA1302 are available still from Motorola in the
number MJL3291/MJL1302 are still in production are meant for audio. They are also available in Matched pairs. BTW
love my Forte 3 great sounding as well.
Post removed 
sean
6,231 posts
 
I currently own three Forte' 3's and two Forte' 6's along with a couple dozen other amps. Have also had Forte' 1A's and Forte' 4's in the past. Ned aka Ferrari has a pair of the Forte' 7's, which i've always been interested in but never tried. Given that they are more powerful monoblock versions of the 4A, i'm sure that they sound quite similar with better dynamics, greater control and improved channel separation.

For best results, these amps work best if left powered up 24/7. Make sure that you have adequate airflow / ventilation around all sides of these amps as they run quite warm. If your Forte' amps are not idling quite warm to the touch, the amp is out of bias and needs repair. I've run across a few amps like this, so be on the look-out for such things if shopping for a Forte'. I've seen sellers of Forte' amps state "amp never gets hot", so that's one that you know is not working properly / in need of repair.

My experience is that the Forte' amps work best with lower impedance loads. They aren't the most ruggedly built amps in terms of current capacity though, so don't expect them to drive very low impedance loads to staggering sound levels while retaining great amounts of control. Having said that, they do work very well / sound good when driving some speakers that other amps may not do all that well with. This could be related to their higher bias levels and reduced crossover distortion that results.

To sum things up, i am a big fan of Forte' amps. When they are running properly i.e. set to factory spec, they are one of the greatest bargains on the used audio market. Combined with solid support components and high quality low impedance speaker cabling, they can form the foundation of a truly accurate yet musical system that is phenomenally cost effective. When tastefully modified beyond factory spec, they can easily compete with and many times beat much more expensive and prestigious amps into the ground. Sean
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