I Have a single Marantz Power Amplifier later known as Model 2. It is my understanding that there were at least three model versions of this particular amplifier
1) Marantz Power Amplifier
2) Marantz Model 2
3) Model 2a
and posibly a Model ( 2b?)
Is this correct? If so how did the variations differ?
Are there any Marantz Mono Tube amp experts here? I know Eli Duttman and Jim McShane are HK Citation 2 fan/experts. Hopefully they, amongst others ( Tom Bavis ? ) can help me decipher the supoposed design differences.
In the example I have, it has a blue colored selenium rectifier marked RS065Q manufactured by the International Rectifier Corp. My concern is that the Rider Manual doesn't list peak current (not available? according to the listing) I found its specs here https://worldradiohistory.com/BOOKS...tifiers-And-Crystal-Diodes-Theodore-Conti.pdf
So how do I come up with a suitable silicone diode/resistor replacement for it? Anyone have any experience with this particular Selenium and know what it can and should be replaced with? The schematic is no help as it only lists the selenium as S.R.1 (sELENIUM Rectifier 1) see schem attached
Scant information out there on this very rare amplifier and I want to be dead careful in restoring it before I do a dim bulb test and if good power it up slowly and incrementally.
The tube complement seems to have been consistent throughout its 3 or 4 year manufacturing run, consisting of 2 X EL34/6CA7 1 x 12AX7 1X6CG7 and 2 X 6AU4 (Damper Tubes?)
I have replaced all the tubes w/known good ones except the test failed 6AU4 tubes. What was the purpose of the damper tubes? Haven't run acrosss this implementation on HK, Scott, Fisher or English stuff of the same period.
Thanks alot.
Len
1) Marantz Power Amplifier
2) Marantz Model 2
3) Model 2a
and posibly a Model ( 2b?)
Is this correct? If so how did the variations differ?
Are there any Marantz Mono Tube amp experts here? I know Eli Duttman and Jim McShane are HK Citation 2 fan/experts. Hopefully they, amongst others ( Tom Bavis ? ) can help me decipher the supoposed design differences.
In the example I have, it has a blue colored selenium rectifier marked RS065Q manufactured by the International Rectifier Corp. My concern is that the Rider Manual doesn't list peak current (not available? according to the listing) I found its specs here https://worldradiohistory.com/BOOKS...tifiers-And-Crystal-Diodes-Theodore-Conti.pdf
So how do I come up with a suitable silicone diode/resistor replacement for it? Anyone have any experience with this particular Selenium and know what it can and should be replaced with? The schematic is no help as it only lists the selenium as S.R.1 (sELENIUM Rectifier 1) see schem attached
Scant information out there on this very rare amplifier and I want to be dead careful in restoring it before I do a dim bulb test and if good power it up slowly and incrementally.
The tube complement seems to have been consistent throughout its 3 or 4 year manufacturing run, consisting of 2 X EL34/6CA7 1 x 12AX7 1X6CG7 and 2 X 6AU4 (Damper Tubes?)
I have replaced all the tubes w/known good ones except the test failed 6AU4 tubes. What was the purpose of the damper tubes? Haven't run acrosss this implementation on HK, Scott, Fisher or English stuff of the same period.
Thanks alot.
Len
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The selenium rectifier should be replaced with a 1N4005 diode or better, with a series 1k 2W resistor.
The original part should be considered hazardous.
The 6AU4 is the HV rectifier, having one diode per envelope.
The original part should be considered hazardous.
The 6AU4 is the HV rectifier, having one diode per envelope.
Ok Thanks for that. Now let's see if anyone can eduMAcate me about the different versions of this amp. Was it strictly cosmetic branding identification changes or were there guts and bones changes/differences between the various model nomenclatures?
There was no "Marantz Power Amplifier" without a model number ever made.
Marantz always applied a model number to all of their products, starting with the Model 1 Preamplifier.
There was an initial version of the Model 1, called the Audio Consolette, limited to a run of 100 units,
before the Marantz Company was established.
Marantz always applied a model number to all of their products, starting with the Model 1 Preamplifier.
There was an initial version of the Model 1, called the Audio Consolette, limited to a run of 100 units,
before the Marantz Company was established.
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I think you are mistaken. Here are two original brochures that came with the amplifer. No Mention of either Model 1 (Audio Consolette) or Model 2 (Power Amplifier) I have seen examples where Model 2 is marked on chassis. These do not have such markings nor serial number tags of any kind. Ditto the original schematics that came with this, I have seen later schematics that clearly had the Model 1 and Model 2 designation labelled.
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Those two were designed by Marantz and built in his house before Sid Smith joined him,
and before the company was established in a factory in 1953. Their production was very limited.
Bill Johnson did much the same thing with Electronic Industries before establishing Audio Research Corp,
although with the Audio Research models, Bill added nice anodized front panels and rack mount handles,
as well as pcbs instead of point to point wiring.
and before the company was established in a factory in 1953. Their production was very limited.
Bill Johnson did much the same thing with Electronic Industries before establishing Audio Research Corp,
although with the Audio Research models, Bill added nice anodized front panels and rack mount handles,
as well as pcbs instead of point to point wiring.
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The material I have here indicates that the first Audio Consolettes up until 1953, when he opened up his own factory in Woodside, were indeed built by Saul at his home but never the Power Amplifier, in which Sidney Smith had the primary hand in designing and was not, in fact, introduced until 1956.
It's curious to me and I just wanted to determine if there were any meat and potato differences between the rumoured model designations of what is now widely referred to simply as the Model 2.
It seemed a good question to ask considering I have an example without a Model 2 designation anywhere to be found on it.
I appreciate you insight Rayma, it seems those early days and designs are still subject to a great deal of mystery and ambiguity.
Rgds Len
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Here are a couple of historic timelines.
The following timeline comes from a Stereo Sound special edition dedicated to Marantz
published in 2003. The book was meant to be distributed to key people in the industry but not to be available for sale.
1911 Saul B. Marantz' birth in Brooklyn on July 11.
1923 Sidney Stockton Smith's birth in Winnetka, Illinois.
1951 Saul B. Marantz begins manufacturing the Audio Consolette in New York
1952 - Audio Consolette (Model 1 original version) vacuum tube monaural preamp. Compliant with 36 types of SP/LP record EQ curves. Two-stage P-K feedback type phono EQ. Uses 12AX7 and 12AU7 in a three-tube structure. 155$ with cabinet, selling at least until 1955.
1953 Marantz Company established in Long Island, New York (44-15 Vernon Blvd.)
1954 Sidney Stockton Smith joins Marantz. Model 1 vacuum tube monaural preamp employing RIAA EQ and tape monitor circuit. Two-stage P-K feedback phono EQ ; 12AX7 three-tube structure. With cabinet: 168$>171$ ; without cabinet.
1956 Sidney Stockton Smith is the Chief engineer for the Model 2. Model 2 vacuum tube monaural power-amplifier. Output stage is 6CA7 p-p, output with UL connection 40W, with triode connection 20W. Uses variable damping (VDFC) mechanism, AC/DC balance/bias adjusting mech., triple circuit input terminal. Uses 1x 12AX7/ECC83, 1x 6CG7, 2x 6CA7/EL34 and 2x 6AU4GTA tubes. (198$>219$)
1957 Marantz Company relocates to 25-14 Broadway, Long Island 6, NY.
Model 3 electronic crossover. Monaural 2-way type. 12 selectable frequencies: 100 / 150 / 220 / 350 / 500 / 700Hz / 1 / 1,5 / 2,2 / 3,5 / 5 / 7kHz. 12dB/octave slope. Uses 12AX7 in three-tube structure. Without cab. with power-supply: 90$ ; with cabinet: 105$.
1958 Model 5 vacuum tube monaural power-amplifier. Output stage is 6CA7 p-p, output with UL connection is 30W. Basic circuitry is the same as Model 2, rationalized for use as multi-amplifier. Uses 1x 6BH6, 1x 6CG7, 2x 6CA7/EL34 and 1x GZ34 tubes. Without grille: 147$ ; with grille: 154,50$.
Model 6 stereo adapter for Model 1: 45$. Two types available: Model 6H (vertical) or Model 6V (horizontal).
Flavio Blanco participates to the development of the Model 7. Blanco will later be responsible for development and design of the solid-state amps as technical dept. head in the amplifier section of the Company. Model 7 vacuum tube stereo preamplifier released in December. Uses six ECC83/12AX7 tubes, three-stage NF eq and NF step-switch tone control.. Without cabinet: 249$ ; with cabinet: 273$.
1959 Model 8(A) vacuum tube stereo power-amplifier. Together with the Model 8B, was the only vacuum tube Type 1 power supply power amplifier produced by Marantz. The Model 8(A) is also know as the stereo model that combines two Model 5 in one chassis. Power supply section is a voltage doubler rectifier system with silicon diode. Output stage is 6CA7 p-p, output with UL connection 2x 30W. Uses 2x 6BH6, 2x 6CG7 and 4x 6CA7/EL34 tubes. Without grille: 237$ ; with grille: 246$.
Model 9 and Model 9R vacuum tube monaural power-amplifier. Output stage is 6CA7 parallel p-p, output with UL connection 70W, with triode connection 40W. Uses 2x 6DJ8/ECC88, 1x 6CG7 and 4x 6CA7/EL34 tubes. First vacuum tube amp to use a front panel. Uses active low-cut filter, phase switching, crossover NF circuit and elaborate phase correction. Power supply is a voltage double rectifier with silicon diode.
Standard type: 324$>384$ ; rack-mounted Model 9R: 354$>414$.
1961 Model 8B tube stereo power-amplifier, improved version of Model 8(A) with increased output of 2x 35W. Basic circuit of the Model 8B is that of the Model 9, and the Model 8B also uses crossover NF circuitry and elaborate phase correction system. Power supply is a voltage double rectifier with silicon diode. Uses 2x 6BH6, 2x 6CG7 and 4x 6CA7/EL34 tubes. With grille: 258$>273$ ; Without grille: 249$>264$.
Richard Sequerra joins Marantz.
1962 Marantz announces a new concept by using an oscilloscope tube for multipath/tuning indicator in a prototype of the Model 10 FM tuner ; The Chief Engineer is Richard Sequerra.
1963 Model 10B vacuum tube FM tuner with 3" oscilloscope. 650$.
SLT-12 record player with linear tracking tonearm.
1964 Superscope takes over management of the Marantz Company in America.
1965 Marantz moves from New York to California. Model 7T solid-state preamplifier, sold through Nippon Gakki in Japan (aka Yamaha).
The following timeline comes from a Stereo Sound special edition dedicated to Marantz
published in 2003. The book was meant to be distributed to key people in the industry but not to be available for sale.
1911 Saul B. Marantz' birth in Brooklyn on July 11.
1923 Sidney Stockton Smith's birth in Winnetka, Illinois.
1951 Saul B. Marantz begins manufacturing the Audio Consolette in New York
1952 - Audio Consolette (Model 1 original version) vacuum tube monaural preamp. Compliant with 36 types of SP/LP record EQ curves. Two-stage P-K feedback type phono EQ. Uses 12AX7 and 12AU7 in a three-tube structure. 155$ with cabinet, selling at least until 1955.
1953 Marantz Company established in Long Island, New York (44-15 Vernon Blvd.)
1954 Sidney Stockton Smith joins Marantz. Model 1 vacuum tube monaural preamp employing RIAA EQ and tape monitor circuit. Two-stage P-K feedback phono EQ ; 12AX7 three-tube structure. With cabinet: 168$>171$ ; without cabinet.
1956 Sidney Stockton Smith is the Chief engineer for the Model 2. Model 2 vacuum tube monaural power-amplifier. Output stage is 6CA7 p-p, output with UL connection 40W, with triode connection 20W. Uses variable damping (VDFC) mechanism, AC/DC balance/bias adjusting mech., triple circuit input terminal. Uses 1x 12AX7/ECC83, 1x 6CG7, 2x 6CA7/EL34 and 2x 6AU4GTA tubes. (198$>219$)
1957 Marantz Company relocates to 25-14 Broadway, Long Island 6, NY.
Model 3 electronic crossover. Monaural 2-way type. 12 selectable frequencies: 100 / 150 / 220 / 350 / 500 / 700Hz / 1 / 1,5 / 2,2 / 3,5 / 5 / 7kHz. 12dB/octave slope. Uses 12AX7 in three-tube structure. Without cab. with power-supply: 90$ ; with cabinet: 105$.
1958 Model 5 vacuum tube monaural power-amplifier. Output stage is 6CA7 p-p, output with UL connection is 30W. Basic circuitry is the same as Model 2, rationalized for use as multi-amplifier. Uses 1x 6BH6, 1x 6CG7, 2x 6CA7/EL34 and 1x GZ34 tubes. Without grille: 147$ ; with grille: 154,50$.
Model 6 stereo adapter for Model 1: 45$. Two types available: Model 6H (vertical) or Model 6V (horizontal).
Flavio Blanco participates to the development of the Model 7. Blanco will later be responsible for development and design of the solid-state amps as technical dept. head in the amplifier section of the Company. Model 7 vacuum tube stereo preamplifier released in December. Uses six ECC83/12AX7 tubes, three-stage NF eq and NF step-switch tone control.. Without cabinet: 249$ ; with cabinet: 273$.
1959 Model 8(A) vacuum tube stereo power-amplifier. Together with the Model 8B, was the only vacuum tube Type 1 power supply power amplifier produced by Marantz. The Model 8(A) is also know as the stereo model that combines two Model 5 in one chassis. Power supply section is a voltage doubler rectifier system with silicon diode. Output stage is 6CA7 p-p, output with UL connection 2x 30W. Uses 2x 6BH6, 2x 6CG7 and 4x 6CA7/EL34 tubes. Without grille: 237$ ; with grille: 246$.
Model 9 and Model 9R vacuum tube monaural power-amplifier. Output stage is 6CA7 parallel p-p, output with UL connection 70W, with triode connection 40W. Uses 2x 6DJ8/ECC88, 1x 6CG7 and 4x 6CA7/EL34 tubes. First vacuum tube amp to use a front panel. Uses active low-cut filter, phase switching, crossover NF circuit and elaborate phase correction. Power supply is a voltage double rectifier with silicon diode.
Standard type: 324$>384$ ; rack-mounted Model 9R: 354$>414$.
1961 Model 8B tube stereo power-amplifier, improved version of Model 8(A) with increased output of 2x 35W. Basic circuit of the Model 8B is that of the Model 9, and the Model 8B also uses crossover NF circuitry and elaborate phase correction system. Power supply is a voltage double rectifier with silicon diode. Uses 2x 6BH6, 2x 6CG7 and 4x 6CA7/EL34 tubes. With grille: 258$>273$ ; Without grille: 249$>264$.
Richard Sequerra joins Marantz.
1962 Marantz announces a new concept by using an oscilloscope tube for multipath/tuning indicator in a prototype of the Model 10 FM tuner ; The Chief Engineer is Richard Sequerra.
1963 Model 10B vacuum tube FM tuner with 3" oscilloscope. 650$.
SLT-12 record player with linear tracking tonearm.
1964 Superscope takes over management of the Marantz Company in America.
1965 Marantz moves from New York to California. Model 7T solid-state preamplifier, sold through Nippon Gakki in Japan (aka Yamaha).
Thanks for this Rayma!
The 1956 notation of a VDFC Variable Damping System is of particular interest. Still am not sure at all what its design/intent/effect was. Was this the reason for employing GAU4GT tubes other than exclusively as half wave HV rectifiers?
I have the Model 1 and 3 sitting on my bench at present as well w/power supplies for Model 1 and 3.
I see the variable damping had nothing to do with the 6AU4Gs but was used for particular speaker loads?
In the early days of HiFi, before Theil/Small modeling, speakers had very large frequency response errors at best, and were designed often cut-and-try. Because all speakers' impedances vary with frequency, adjusting source (driving) impedance adjusts frequency response. Things were much more ad hoc in those days, and trying for any sort of flatness was worth a little effort. Adjust by ear.
All good fortune,
Chris
All good fortune,
Chris
Yes, a special pot at the amplifier output added a controlled amount of positive feedback to modify the damping factor.
The pot may need cleaning by now.
Thanks gents! I very much appreciate you taking the time to respond. It would appear that the Model 2 amplifier was the same throughout its lifetime of manufacture contrary to some vague speculation I found on the INTER-WEB. The only differences would appear to have been purely cosmetic ie: labelling/chassis markings and not in structural/circuit design?
Thanks Rayma, I do. The Model 1, 2 and 3 in my shop all came with extensive and original documentation. Nonetheless your post will be helpful for some other inquisitive Marantz 2 fan/owner somewhere down the line, I'm sure.
Best rgds Len
I have a pair of Model 2's that do not say Model 2 anywhere on either of the amplifiers, so they definitely exist.
Hey I just found a little more info for you about the early versions without serial numbers. Check the bottom of the amplifier right in between the two feet. You’ll likely see the serial number stamped there in an almost diy looking fashion.