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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.

Associated gear
Click to view my Virtual System

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

ferrari
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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semi
649 posts
 
Recently picked up a 4A for my sister since she had tight budget and I had an 1A long time ago and liked it. Forte 4A has to be the biggest bang for the buck in audio world now. It's dynamic, smooth, silky with proper amount of texture, depth layering, and transparent. You name it, it has it. It will rival anything out there, and better the big Pass X-350 in most area which I used to own.

Forte 4A is driving my Sonus Faber Amati Homage now which is normally handled by BAT VK-75SE. If I was blindfolded, I would not guess it was solid state. It's that smooth.

It's so good I was debating if I want to give it up for my sister :)
marktime
3 posts
 
I am not sure where the people who are posting that the
IBGT transistors are no longer available but this is
fictional. Possibly the same exact device say 2sc3281 is not in production, however there are present day versions
for a full replacement of this device made by both
Toshiba ( the orignal manufacturer )as well as Motorola
and others that are in many ways as good if not better.
IE a second generation of IGBT's that are even more
reliable than the previous device. The new Motorola IBGT's
are in particular aimed at and designed for low distortion
audio . Just wanted to clear up some confusion. I presently own a pair of 3's and love em. Open clear
with the advantages of mosfet by bi polar qualities as well
(IE tube like sound due to limited stages and very limited
negative feedback).. For any interested check out the
DIY.com group. The IGBT is far from dead.
Cheers
barney1010
11 posts
 
I read this post years ago, and then I picke4d up the old stereoph8ile from November 1992 about the Model 4 and the 6. I bought the 6, it replaced an old Carver tfm-55. I liked the Carver more, the 6 sounded terrible to me. I had planned on buying the 6, and having it re-biased my Jon Soderberg who happens to live about ten miles from me. But, it sounded so bad, I begged Jon to take it ASAP, and he put in four conrad dublier (misspelled?) capacitors at 31,000 uf each, and Jon re-biased it. What a nice sounding amp, I am not sure what is sounds like in comparison to a 4a, but I am very happy with this amp. It is very detailed in the high end, and my BAT VK-D5 tamed the slightly metallic midrange......Now with a Van Alstine Transcendence 7ECR on the way, I will find out just how good it really sounds. I was using an audible ilusions Modulus and a FET-2 threshold before. I spent 1050 dollars for this amp with the upgrade, I am thinking about buying another to bi-amp...........
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