Better beware of this Marantz. It's a typical low cost restoration. Wima clean up things and alter the sound very much. And he made the fault not to use axial caps. So this is an amateur restoration, not a pro one to me. And not one to high quality standards, too.
@Freddi: never try to to compare those gear with modern tube amps. Of course it can be done different, maybe technically better. But would you compare a Mercedes W110 technically with a modern W213, the same result will be shown. Every technical aspect in the new model will be better, more perfect. Is that the reason why you want to drive an old Mercedes, because its so much worse compared to the new generation? Of course, its not. You can be aware of all the technical shortcomings of that period of gear, and still enjoy the old car.
Because what you listen to is so much more complex than a technical approach and what you feel when driving an oldtimer is so much more than its technical shortcomings.
Some say, modern Mercedes cars has lost all its personality and handling touch they once had. Because they are technically so perfect. The absolute same could be said about audio gear. Hear it, repair only when broken and with original parts (or the nearest quality you can find) and enjoy it. Or switch to new gear. An "improved" version is surely being on sale from the asians. Maybe with hyper modern stabilized power and still much more cheaper. Choose your own way. But never sacrifice old original gear in the way this amateur "technician" shows.
@Freddi: never try to to compare those gear with modern tube amps. Of course it can be done different, maybe technically better. But would you compare a Mercedes W110 technically with a modern W213, the same result will be shown. Every technical aspect in the new model will be better, more perfect. Is that the reason why you want to drive an old Mercedes, because its so much worse compared to the new generation? Of course, its not. You can be aware of all the technical shortcomings of that period of gear, and still enjoy the old car.
Because what you listen to is so much more complex than a technical approach and what you feel when driving an oldtimer is so much more than its technical shortcomings.
Some say, modern Mercedes cars has lost all its personality and handling touch they once had. Because they are technically so perfect. The absolute same could be said about audio gear. Hear it, repair only when broken and with original parts (or the nearest quality you can find) and enjoy it. Or switch to new gear. An "improved" version is surely being on sale from the asians. Maybe with hyper modern stabilized power and still much more cheaper. Choose your own way. But never sacrifice old original gear in the way this amateur "technician" shows.
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FWIW those should be very nice coupling caps - Jensen copper/pio w. silver leads.
by clean things up (WIMA) would be a more clinical sound I'd think vs original capacitors
in the tone control section.
by clean things up (WIMA) would be a more clinical sound I'd think vs original capacitors
in the tone control section.

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I had the opportunity to see for myself, with an old "combined" that was in perfect condition but not working (valves were missing) in a summer home of my in-laws in the province of Córdoba. Had artificial field magnet! I think I remember it was 12 inches. I borrowed it, and made it work, but it didn't make any good impression on me at all ..... so the next year it returned to its place, as appropriate.
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Its very understandable that the listening preferences have changed and still change with time. And any speaker needs an enclosure or (at least) the right place to be installed. I bet many wouldn't love old field coil speakers but if you are on a way towards ultimate quality in audio, voila, what will pop up right in your face? All the best speakers use field coils! So ask yourself, maybe you have done something wrong in the environment which let the speaker not play at its maximum potential. Often the reason is not the gear, its the user who makes errors. Or this speaker isn't for the taste of the owner. It could be all reasons why a component plays low quality. But don't blame the speaker (if it was in working condition). Speaker technology has been developed in full since ages and nothing new has happened. But still they try to tell us, every year a new sensation in this field of research. Just marketing speech.
FWIW those should be very nice coupling caps - Jensen copper/pio w. silver leads.
by clean things up (WIMA) would be a more clinical sound I'd think vs original capacitors
in the tone control section.
Exactly those Jensen are the typical boutique parts. Jensen with copper foil, Jensen with silver foil, Jensen with pure gold foil.
NO reputable capacitor company has done such things in the past.
Sprague had its "Vitamin Q" snake oil, but every PIO company has a name for this PCB containing oils and their products at that time.
I dislike Jensen because of their boutique and snake oil status among audiophiles. Otherwise, why has he discontinued its choice and switched to cheap WIMA's? And then choose the wrong type, radial style instead of axials?
This says to me its a complete amateur tech, a non professional and without any knowledge what an excellent restoration differs to an amateur one.
probably to be viewed more as an "well-meaning update" rather than restoration. WIMA radial lead capacitors are made for PC board, and thus require lead extension to have any reach.
These Jensen capacitors have a very limited life .In hot environments don't use them .All these old gear have secrets ,some cheap components of this era can be genuine marvels in the circuit .
.............. And any speaker needs an enclosure or (at least) the right place to be installed. I bet many wouldn't love old field coil speakers but if you are on a way towards ultimate quality in audio, voila, what will pop up right in your face? All the best speakers use field coils !
..................
I have to admit that what appeared on my face is an expression of stupor at that statement.😕
I don't know of modern speakers with field magnets .....
I have seen developments with various small neodymium magnets, oval voice coils, but what you say puzzles me.
Can you give examples and attach photos ?
PS : Maybe it's a problem with my terrible English, do you speak in the present or past?
Do they use or did they use?
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The best is always a subjective term, so I wrote about whats best for me (and a small number of audiophiles). You may have never heard of them because the audio world is divided in technology niches. And most of the speaker manufacturers (and customers) are happy to use a speaker without the need for a power supply. So at some point of the speaker development history the industry was ready to bring permanent magnet speakers on the market which had the same magnetic strength than the former electrodynamic models. But they lost the ability to be fine tuned in their parameters. And to use permanent magnets mean a different quality in the magnetic fields. You may have noticed, neodymium, ferrite, alnico, all those types of speakers sound a little different. Thats because their magnetic materials are different. With a field coil instead, you will hear differences in the speakers power supply. But otherwise, a field coil has very little own sound signature. Not as much as a permanent magnet. As industry has switched over to them, speaker designers use them. Even in high costly designs you will find cheap ferrite speaker chassis employd.
Why is that? Because of a maximization of profit in the companies. Its not because they are the best. Its because they are cheap, but their sound is acceptable to the market and nobody criticizes them for using them. Its accepted by customers and the press media testers of those gears. But is this the best, cream of the crop? No, of course not.
The best are field coil chassis that cost a fortune. I talk about the speaker chassis itself, not the whole speaker including cabinet, dividing network. They are even far more expensive. And they are rare today for the reasons I gave before. If you havent heard of them, just try google and you will see. I will throw some Brands here, GIP, Wolf von Langa, Fertin, A23, Rullit, Shindo, EMS, Line Magnetic. And yes, I've used them since some decades and they were often fabulous sounding. Very transparent, very fast, very dynamic and involving. With much less colorations than the perm. magnet versions.
Why is that? Because of a maximization of profit in the companies. Its not because they are the best. Its because they are cheap, but their sound is acceptable to the market and nobody criticizes them for using them. Its accepted by customers and the press media testers of those gears. But is this the best, cream of the crop? No, of course not.
The best are field coil chassis that cost a fortune. I talk about the speaker chassis itself, not the whole speaker including cabinet, dividing network. They are even far more expensive. And they are rare today for the reasons I gave before. If you havent heard of them, just try google and you will see. I will throw some Brands here, GIP, Wolf von Langa, Fertin, A23, Rullit, Shindo, EMS, Line Magnetic. And yes, I've used them since some decades and they were often fabulous sounding. Very transparent, very fast, very dynamic and involving. With much less colorations than the perm. magnet versions.
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- to arrive at a close approximation of C7's "sound" - - study its power supply.
Half wave rectification, daisy chained RC filtering. Relatively "high" output impedance vs modern concerns of low Z and tight regulation.
Hi freddi
I'm confused here ......
Full-wave rectification (with diodes) is seen in the full circuit attachment
And in the attachment with the description in Japanese ( link ), I also see full wave rectification, in this case with thermionic valves ... (double triode)
The first models were half wave? .....
Marantz 7 Preamplifier Circuit - Other_circuit - Amplifier_Circuit - Circuit Diagram - SeekIC.com
Attachments
re:fileld coils - - one example: Wolf von Langa | WVL | High End Loudspeakers
I don't know the history of that schematic - perhaps going through old literature would find out its place
I don't know the history of that schematic - perhaps going through old literature would find out its place
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Half wave solid state retification and the rest is correct per service manual at Hi Fi Engine
and screenshot from its service manual
https://i.imgur.com/TDt15oz.png

and screenshot from its service manual
https://i.imgur.com/TDt15oz.png
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You wrote that part, not your late friend, right?
Well, I think that it is not so, the treatment with various materials for "doping" of the cones (some really exotic) of the current speakers has introduced tangible improvements with respect to the speakers of those years.
I had the opportunity to see for myself, with an old "combined" that was in perfect condition but not working (valves were missing) in a summer home of my in-laws in the province of Córdoba. Had artificial field magnet! I think I remember it was 12 inches. I borrowed it, and made it work, but it didn't make any good impression on me at all ..... so the next year it returned to its place, as appropriate.
Computer-aided design has made major improvements in speaker technology, especially in cones. They do not introduce tones of the cone material as before.
So I insist that that Marantz 7 preamp may sound great with a tube amp to complement it and high-impedance, good-sensitivity speakers, but plug it into a modern SS amp and current speakers and it won't be anything great.
In that example, the whole equation changes, such as input impedance and sensitivity mismatches between the Marantz 7 and the modern SS amplifier. But it is just my opinion, I can be wrong, I leave a link of a similar "experiment" that I never knew if it came to fruition because the author did not continue to post .....
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Esa parte la has escrito tú, no tu fallecido amigo, no es cierto ?
Pues yo pienso que no es tan así, el tratamiento con materiales varios para " dopaje " de los conos ( algunos realmente exóticos ) actuales de los parlantes ha introducido mejoras tangibles con respecto a los parlantes de esos años.
Tuve la oportunidad de comprobarlo por mi mismo, con un viejo " combinado " que estaba en perfecto estado pero sin funcionar ( faltaban válvulas ) en una casa de veraneo de mis suegros en la provincia de Córdoba. Tenía imán artificial de campo ! Creo recordar que era 12 pulgadas. Lo tomé prestado, y lo hice funcionar , pero no me causó en absoluto ninguna buena impresión..... asi que al año próximo volvió a su lugar, como corresponde.
El diseño asistido por computadoras ha hecho mejoras importantes en la tecnología de los parlantes, sobre todo en los conos. No introducen tonos propios del material del cono como antes.
Por eso, insisto en que ese preamplificador Marantz 7 puede sonar estupendo con un amplificador valvular que lo complemente y parlantes de alta impedancia y buena sensibilidad, pero conéctalo a un amplificador SS moderno y parlantes actuales y no será nada extraordinario.
En ese ejemplo, cambia toda la ecuación, como ser las incompatibilidades de impedancias y sensibilidades de entradas entre el Marantz 7 y el amplificador SS moderno. Pero es sólo mi opinión, puedo estar equivocado, dejo un link de un " experimento " parecido que no supe nunca si llegó a buen término porque el autor no siguió posteando.....
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Why are you writing in 2 languages?
cathode followers in the marantz 7 makes for a 1k output impedance, modern SS amps can have 20k, i see no problem mating the tube preamp with an SS amp...
Half wave solid state retification and the rest is correct per service manual at Hi Fi Engine
and screenshot from its service manual
https://i.imgur.com/TDt15oz.png
That is full wave rectification, two rectifier diodes (solid state or tubes) conduct in the positive half cycle and the other two in the negative half cycle
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cathode followers in the marantz 7 makes for a 1k output impedance, modern SS amps can have 20k, i see no problem mating the tube preamp with an SS amp...
I have had many problems to achieve a good match.
Why are you writing in 2 languages?
Why shouldn't I if the forum supports it? It is only for a better understanding with people who are fluent in both languages.
As long as you write in English, you can also do it translated into your native language
re:fileld coils - - one example: Wolf von Langa | WVL | High End Loudspeakers
I don't know the history of that schematic - perhaps going through old literature would find out its place
Impressive design, they look great, because there is no technical data?
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they also liked the Aikido, but not as much as the CCDA...
That Eric White chap invented the CCDA in 1937, yet it was not popularized until Broskie
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