Amp/Preamp Asylum: REVIEW: Forte 4A Amplifier (SS) by Marc Bratton

Model:	4A
Category:	Amplifier (SS)
Suggested Retail Price:	$1895.00
Description:	50wpc IGBT based Class A amplifier
Manufacturer URL:	Not Available
Manufacturer URL:	Not Available

Review by Marc Bratton on July 02, 2004 at 20:52:29
IP Address: 63.184.64.173

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I have always had a love/hate relationship with SS amps, especially Class A/B ones. On the one hand, I readily recognize their superiority to most conventional tube amplifiers in the areas of clean, tight bass, inky black background, quickness and dynamics, and squeaky clean sound. Their downfall to my ears has always been what I refer to as 'textural issues'.
In short, every Class A/B amplifier I've ever heard imparts a grain, however fine, to the instrument timbres, which does a lot to subliminally remind me I'm listening to an electronic reproduction. Every one of them...this is one area where tubes excel. Their grain free reproduction has been the only type I've been able to live with long term, despite their other shortcomings.
That said, I couldn't help but notice how much a SS Class A/B amp I've reviewed in these pages (AVA Omega III 260)just made my Magnepan MG12QR's come ALIVE. But, mmmm...there's that textural issue again. I mentioned it in that review. Couldn't live with it long term. Upon reflection, I realized the ONLY SS amp I'd ever been able to live with long term was my old Class A Forte 1a, which brings us (finally!) to this review.
The 4a is the sucessor to the 1a. The 1a used bipolar output transistors; the 4a uses the very exotic and expensive (and now unfortunately unobtainable)IGBT's-insulated gate bipolar transistors. The other change from the 1a is the 4a got a restyling by Rene Besne (sp?). It just exudes class...it looks very much like Electrocompaniet's amps of the same vintage (mid 90's). The 1a looks dowdy by comparison. They are otherwise very similar.
Though rated at 'only' 50 watts into 8 ohms, this thing is one powerful amplifier. It seems to have as much headroom as my AVA did, which was rated at 260 watts into 4 ohms. When you look at the size of the moose of a transformer, and the array of power capacitors in this amp, you know it's no weak sister.The output fuses are fast blow 8 ampers, if that tells you anything. It drives my insensitive Magnepans with aplomb. And WHAT aplomb! The amp I took out of line to try out the Forte 4a was an all tubed Conrad Johnson MV75A1, upgraded by Bill Thalmann of Music Technology. My ear is most attuned to the all important midrange, so when I heard this amp deliver a midrange that was about 98% of the CJ, I was impressed, to say the least! Cutting to the chase, the CJ has a slightly more refined and silky treble, no doubt about it.Its midrange is also slightly more fleshed out and fuller with female vocals. The Forte betters it decisively in deep bass, dynamics, PRAT,drive and just plain BALLS. AND it has enough finesse that my ears just go "Ahhhhhhhh" when I listen to my beloved string quartets. There is NO graininess, NO listener fatigue, and NO sense of anything synthetic or electronic going on. Driven with my tube preamp (AI 2C), it has brought my system the closest it's ever been to just flat out sounding like the musicians are in the room. This is a synergistic pairing that seems to have rendered the tube/SS debate moot. It really seems to have most of the best of both technologies, without the usual weaknesses of either. It is an amp that I intend to live with a long time.
These amps have a reputation for excellent reliability, so I wouldn't let the IGBT bugaboo deter me from getting one. Jon Soderberg (one of Forte's chief engineers, who runs his own business repairing and upgrading Threshold amps-Forte was a sister company) tells me he's never seen an IGBT fail. These devices are stable into a fraction of an ohm, and are supposed to be tough as nails. So, if you're looking for a synthesis of the best of tubes and SS, and need 'only' 50 Class A watts, it's hard to see how you could do much better.

Product Weakness: Forte doesn't exist anymore, so you'd need to rely on Jon Soderberg for product support.
Product Strengths: This is about the most disarmingly natural sounding SS amp I've ever heard. Exc. build quality, very reliable.

Associated Equipment for this Review:
Amplifier:	Forte 4a/CJ MV75A1
Preamplifier (or None if Integrated):	Audible Illusions 2C
Sources (CDP/Turntable):	Teres 200/MorchUP4/ShureV25VxMR
Speakers:	MagnepanMG12's (crossovers heavily upgraded)
Cables/Interconnects:	Cardas 5C/DH Labs
Music Used (Genre/Selections):	Everything except rap and Nashville
Room Size (LxWxH):	26 x 14 x 8
Room Comments/Treatments:	RPG foam on wall behind 12's
Time Period/Length of Audition:	1 year.
Other (Power Conditioner etc.):	Brickwall 20AUD/Monster HTS2000
Type of Audition/Review:	Product Owner

Product Weakness:	Forte doesn't exist anymore, so you'd need to rely on Jon Soderberg for product support.
Product Strengths:	This is about the most disarmingly natural sounding SS amp I've ever heard. Exc. build quality, very reliable.