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Marantz 15

Solid State Stereo Power Amplifier (1968)

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Marantz 15


Power output: 60 watts per channel into 8Ω (stereo)

Frequency response: 10Hz to 60kHz

Total harmonic distortion: 0.1%

Damping factor: 150

Input sensitivity: 1V

Signal to noise ratio: 90dB


schematic   English - ajt9170

service manual (partial)  English - CDFixer

service manual   English - renzo54

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The Sound Of Marantz

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Reviewed Jun 10th, 2016 by dlb945

I was lucky to find a working example about 20 years ago (1996) and placed it on the Amp-Shelf driving it with a Model 7T Preamplifier. Speakers were 1978 Klipschorns and signal source was a HK T65 Turntable with a Shure V15-III cartridge. The recording was an original Chicago Transit Authority album and I placed the stylus in the groove and let the music loose!

The room immediately lit up with an acoustic representation of the studio. Then, the instruments began to appear in space, locked into an image quite real. I sat down and listened to all of the first side marveling at the sound of Castenets as the side finished. Impossibly real!

Over the years, I've updated both Marantz units with newer signal and power capacitors as well as several resistors. I own both Marantz units today with the 7T always in place and the Model 15 sharing duty with a modified Dynaco ST-70. The two amps have similar sound with the Model 15 giving the tightest bass and the ST-70 giving a a bit more lower midrange.

The Model 15 is quite tube-like, dead quiet through Khorns, and never heats up. I love it!

Reviewed May 03rd, 2016 by aquiles

Very silent, musical and powerful amplifier.Mine was serviced and changed caps; after 50 years those caps were on their last breath.You can feel the hand of Sid Smith on this one once serviced.

Reviewed Jan 10th, 2013 by zenchua

Marantz Model 15 Vintage Power Amp – A hidden gem to be uncovered

My first audition with this old school amp turned out to be an unexpected mind-blowing experience, albeit this vintage amp was made almost half a century ago, around the 1966 timeframe. Marantz 15 impressed upon me greatly for its ability to dig out all the musical details and present them all nicely together and project you with the soul and inspiration of music, and just this alone is already thrilling and brilliant.

With 15 playing on my familiar sources, I was listening all the way through the end of the pieces, just for the sheer pleasure of hearing the music, as if for the first time. This kind of listening pleasure convinced me that I am hearing into the truths of recording, bringing me closer to the musical essence. Many of those once considered less well recorded or unpleasant sources suddenly came alive sounding “so nicely” and regained their lost glory.

It is that kind of presence and aliveness drew my immediate attention. Midrange vocals from the 15 are lucid with clarity in lyrics. Sax blowing was full of vibration texture and airiness, nearly tube alike. The bottom bass was particularly forceful and dynamic (Damping factor “150”). I could feel the slam and punch of those dynamic mid-bass drum beats. The high timbre might not be very well extended but sounded so harmonically right and pleasant. In fact, this absence of high frequency flare or noise allows for a better focus on musical essence. To demonstrate harmonic purity and transient response, I played a solo piece of acoustic guitar. And I heard it from 15 the plucking of the guitar strings and reverberations from the guitar chamber, so lively never before. Soundstage wise, 15 delivered the width with good depth and excellent imaging. This kind of sound quality should not be expected from an old amp of this age. This particular piece of 15 under review was still in its original condition (SN #10010).

All in all, Marantz 15 is such a wonderful vintage amp. It is capable of giving you the harmonic purity, warmly and yet inviting. The 15's distinct musical attributes convey the flow of emotion of the recorded performance so effortlessly, a trait all too rare in today's modern amps. With 15 coupled with my Altec Model 15 horn speakers, I am now able to sit back, relax and listen to the music, not to the speakers any longer. This kind of new listening experience is just awesome.

Current resale value of Marantz 15 on eBay is about $600. Judging its remarkable performance, it should only appreciate in value over the time horizon. Hence, this is one truly hidden gem to be uncovered one day.



Marantz Model 15

I've had a Model 15 in my spare collection for years. Finally took it out last weekend to drive my Elac 4pi super tweeters. And it sounds great, far better than expected. The extreme highs are clear, and even if cranked up way too far still sounds marvelous. People say vintage NY Marantz has the champagne sound and I hear it that way.

I've always known this amp was special and that's why I bought it. The Model 15 was the last power amplifier designed by the legendary designer of Marantz tube amplifiers, Sid Smith. This was the model owned and used by Saul Marantz himself until his death many years after selling the Marantz company. The equally famous James Bongiorno once said it was one of the best transistor amplifiers ever designed, and he (James) learned a lot from it (he worked at the Marantz company around the time the Model 15 was being designed). Funny, though, looking at the schematic I can't figure out what James learned from it. It doesn't look exactly like modern transistor amplifiers, nor does it not look like them. This was one of the earliest transistor amplifiers. But Sid Smith did something here that makes this always sound good, and I hope to figure it out someday.

It's funny now to have a relatively large chunk of metal for a 60W/channel amplifier, it weighs more than many ordinary 200w/ch amplifiers nowadays. But due to clever design, most of the metal also serves as heat sinking, and it's almost beautiful as functional art.

The front lights look a bit strange now but functionally show which amplifiers are actually powered (that's a convenience feature) and will show current overload when and if it actually occurs (I saw it while testing the amp years ago). When there is current overload, the ears on the sides of the power lights glow blue (cool!). Cleverly, the overload lights themselves are part of the overload circuit (but that does also mean you have to replace the lights when they go out, but as they shouldn't be lighting up often they shouldn't burn out often either). The overload lights are great for me as I can tell at a glance if too much power is going into my supertweeters, which I might not even hear.

re: Marantz Model 15

To be more precise, James Bongiorno said it was a masterpiece of design, and it still competitve today (as of 2001). This design was taken for the amplification section of the model 18.

re: Marantz Model 15

Dawson Hadly, was it's creator.

This website is not affiliated with or sponsored by Marantz. To purchase 15/Model 15 spares or accessories, please contact the company via their website or visit an authorised retailer.