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RC-M90JW versus RC-M90C


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#1 Transistorized

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Posted 09 January 2017 - 01:22 PM

I am sure if anyone can answer this question the guru's on here can.

 

Is there a difference in Amplifier Power output from a RC-M90JW to a RC-M90C? Another words one that is louder than the other? My friend was telling me that he thought the Canadian model made less RMS output power. I thought the internals were all the same just that the C designated a model sold in Canada and the JW was sold in the US.

 

Anyone out there that can clear this up? Thanks



#2 docs

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Posted 09 January 2017 - 01:29 PM

Not sure about those exactly but the LB is rated at 61W.
I think all others are rated at 70W.

#3 Superduper

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Posted 09 January 2017 - 01:33 PM

The C version was sold in Canada and I'm pretty sure a fixed 110v power supply.

 

The JW version has a multi-voltage capable power supply (115/230).

 

Aside from the power supply differences (and sometimes, tuner and I/O variances), I believe internally, they are otherwise pretty much the same.  Locally, different ratings may apply so it's not unusual to see the same equipment have slightly different ratings but it's all a matter of how you rate them.  The Victor model, aside from the 100v input, may have some other differences as well in the features.



#4 Hisrudeness

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Posted 09 January 2017 - 01:40 PM

This is what I thought
The boards and amp chips were all the same as well as the speaker ratings. JW, C, LB & L (Europe) were all the same internally apart from the different power packs. The sticker ratings were regional but the internals were the same.
Reports from collectors with multiples of this model saying that one sounded better than the other was due to the condition of a particular box's caps and stuff after 30 odd years.
Would this be plausible?

#5 Transistorized

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Posted 09 January 2017 - 01:52 PM

This is what I thought
The boards and amp chips were all the same as well as the speaker ratings. JW, C, LB & L (Europe) were all the same internally apart from the different power packs. The sticker ratings were regional but the internals were the same.
Reports from collectors with multiples of this model saying that one sounded better than the other was due to the condition of a particular box's caps and stuff after 30 odd years.
Would this be plausible?

This sounds very plausible. I can go with that. The wattage that my friend must be referring to must be the power supply differences between the two models. That's power consumption....not output power from the Amp.

 

I have known many people to swap parts from one to the other without any compatibility issues. When I mentioned this he said that he was aware they had enough similarities to swap parts but he felt the Amp was more powerful in the JW than the C. That was more where we had our differences in opinion. If the Amp chips and all circuitry is the same then only the power supply must be causing the variance in the wattage shown on the label. In this case they would be referring to the wattage consumed by the unit. Again my friend argued that a more robust power supply drawing more wattage would allow the amp produce more RMS power due to a better supply of voltage. 

 

IDK. My model is a JW but my Amp board had a bad pot and the easiest thing to do was switch it with a good one out of a RC-M90C. I just feel like he is insinuating that my M90 is not as powerful as it used to be because the replacement amp board is less powerful. I have both of the boards here in front of me and all parts are the same. So we ended with me mentioning that my power supply is original so if that is the contributing factor then the board out of the C model should be getting more power to produce more power.

 

This is a friendly argument but a disagreement nonetheless.



#6 docs

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Posted 09 January 2017 - 01:52 PM

Certainly I guess so but they did print different ratings as I see a JW rated at 61W and a C at 70W, both at 120V.

#7 Hisrudeness

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Posted 09 January 2017 - 01:57 PM

Those wattage ratings from the 80s were all over the place Docs. Especially on boomboxes and the marketing and whatnot. Very unreliable.

#8 Superduper

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Posted 09 January 2017 - 03:46 PM

He doesn't know what he's talking about.  They all use the exact same output chips.  The differences between the C and JW version is almost certainly minor, again mostly with the power supply.  Swapping parts between these 2 models will almost certainly be fine.  As far as ratings go, if we take some whiteout and change the numbers in the back so that they look better, will that make one sound better than the other?  The numbers are not set in stone -- they are subject to interpretation and depends entirely on how they are rated.  In other words, maybe one rates it with the power supply installed in the boombox and another rates it on the bench using entirely different set of consumption parameters.  The ratings will be different but both will be accurate.  Also, how about if a PS with exact same components is rated at 61w at a 50% safety margin but the 70w one is rated at a 35% safety margin?  Does the 70w one become more powerful as a result?

 

As for a power supply affecting the output capability of the boombox itself, it's plausible IF and only IF the boombox is drawing enough current to cause a droop in the supply voltage currently installed in which case, a stiffer supply that can maintain the power level will enable the boombox to perform better.  Then again, if you are referring to power supply as the transformer, check them out and you'll note that they are probably identically sized.  It's fair to say that a higher VA rated transformer will almost certainly be larger, as the ability of the transformer to output current depends upon the gauge of the windings and the number of turns to determine the voltage split.  Thicker gauge windings take more room, so the transformer will be larger.  So as long as the power supply is outputting the same voltage to the amp board (regardless of input voltage), then for all practical purposes, the boombox should roughly output the same.  Anyhow, this has been discussed before, many times before already and various suffixed versions (of JVC) vs. power output is really nothing to even argue about.  It's like asking how many more mm taller are you than I?  Maybe it depends on what shoes you are wearing?

 

Bottom line, IF the power supplies are working the way they are designed, in the region they were released, then the output voltage sent to the boombox should be roughly the same and therefore, similar performance should be observed.  It is after all, the voltage that the boombox sees that is important and controls how much power output it produces.  Current consumed by an amplifier is supplied by the transformer based on demand (and same voltage means same current consumption) therefore, except for operating conditions where the boombox is at or near maximum volume where a voltage droop would manifest, wouldn't even be noticed.  However, at maximum volume, if one power supply is stiffer, then that boombox will likely perform better. 

 

Now, that being said, it is not uncommon for folks to use japanese domestic imported models (in this case, Victor M90) connected directly to North American voltage.  Because transformers convert voltages in a set ratio, the victor model will output approximately 20% more voltage when connected to north american mains.  This instantly makes the boombox feel more powerful but could risk damage to the device, especially with long term use.  If you've ever ran a japanese model on USA power, you'll know what I mean...  the VU's will swing higher, the boombox will feel more powerful overall, but at maximum volume, you may observe significantly greater distortion and of course the VU's will no longer be properly calibrated.  This effect varies by model and manufacturer since it all depends upon how much internal regulation was designed into the boombox.  The amplifier portion is typically fed unregulated power.  How the rest of the boombox gets their power varies.  Tuner and digital circuits typically have very precise voltage requirements and would be fed through voltage regulators (which would become stressed since they have to sink more thermal energy).  Preamp and other circuits are sometimes regulated, sometimes not.  I would not operate a Perdisco model on USA power without first swapping out the transformer.  However, the Panasonic RX-7200 is practically a world beater with the 20% higher voltage supplied with the original japanese transformer.  Just my observations.



#9 JVC Floyd

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Posted 09 January 2017 - 04:47 PM

I have the c and jw models and honestly they sound exactly the same with identical output and loudness. I would have thought the m90c would be louder at 70 watts but in reality its exactly the same.

The only time I ever experienced diminished output from these boxes was when either the function switch was dirty or the band selector switches were dirty.

#10 caution

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Posted 09 January 2017 - 04:54 PM

I have the c and jw models and honestly they sound exactly the same with identical output and loudness. I would have thought the m90c would be louder at 70 watts but in reality its exactly the same.

 

That throws me off too. 70W is over 10% more than 61W. Regardless of method, that's fishy. And we're not even talking about that PMPO baloney.



#11 Reli

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Posted 09 January 2017 - 05:15 PM

Reminds me of collectors / Ebay sellers who claim their GF9696 is the "more powerful version"  :lol: 



#12 redbenjoe

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Posted 09 January 2017 - 05:16 PM

I have the c and jw models and honestly they sound exactly the same with identical output and loudness. I would have thought the m90c would be louder at 70 watts but in reality its exactly the same.

The only time I ever experienced diminished output from these boxes was when either the function switch was dirty or the band selector switches were dirty.

floyd is correct -exact same sweet sound  :rock:



#13 Hisrudeness

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Posted 09 January 2017 - 05:21 PM

Bottom line is if the boards, chips and speakers are the same well...there you go.

It's interesting what Norm said about the Japanese domestic boxes. I've heard people say that Japanese domestic Victor M70s sound stronger than the US and European counterparts. If your feeding them 120v instead of 100 then I guess they would sound slightly more roided. The cost is prolonging that at high volume. It's a great point because Japanese boxes do seem to sound better.

#14 baddboybill

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Posted 09 January 2017 - 05:57 PM

Not sure if memory serves but didn't we come to conclusion that the difference was the amp chips were made by different manufacturers? I thought one was Panasonic and other Sanyo? I thought this was discussed in an old post? Mmmm!!!

#15 Transistorized

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Posted 09 January 2017 - 08:00 PM

I like what I'm hearing so far. Its sounding as though I am correct :-)

 

 

 

 



#16 JVC Floyd

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Posted 09 January 2017 - 11:03 PM

Hell even at 61 Watts current draw the m90 is one of most powerful one piece boomboxes ever made and by far the most powerful one piece Boombox I've ever owned. I think a good chunk of that current draw goes to the full logic deck when in use it needs plenty of instant current .

#17 blu_fuz

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Posted 10 January 2017 - 08:29 AM


If you've ever ran a japanese model on USA power, you'll know what I mean...  

 

 

^ Norm, I know exactly what you mean. The Victor M70 is a 100v Jap box. I always plug it in to the US 110/120v outlet and it is just a monster compared to the other M70 series blasters. I know long term is not good to over power it, but it has been holding up with no issues lurking from what I can tell. Have had it running at 1/4 volume for 9hrs straight every day for over a month.

 

 

 

 

I have also swapped parts and pieces from M90 JW's to C's and to LB's and they all work together.

 

 

The 'real' difference that effects the end user (not the end sound) is the physical voltage selector, the radio bands, and the rear panel with the input/output options.

 

 

 

 

M90JW and M90C do have a different wattage rating on the speakers though.

 

C wattage on the speaker is 25W:

Attached File  IMG_5137.JPG   189.02K   19 downloads

 

JW wattage on the speaker is 20W:

Attached File  IMG_5138.JPG   171.28K   9 downloads

 

 

 

LB rear panel, must use line attenuator to listen to RCA line-in through phono jacks:

Attached File  IMG_3932.JPG   221.87K   11 downloads

 

 

JW rear panel:

Attached File  IMG_2297.JPG   226.97K   16 downloads

 

 

C rear panel:

Attached File  IMG_5389.JPG   231.97K   5 downloads

 

 

Some other small things to mention, the power switch boards are different from the JW/C to LB.

 

JW/C power switch board:

Attached File  IMG_3281.JPG   159.88K   5 downloads

 

 

LB power switch board, DOES NOT HAVE FUSE PROTECTION:

Attached File  IMG_3280.JPG   143.78K   6 downloads



#18 blu_fuz

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Posted 12 January 2017 - 04:55 PM

And here is the JVC RC-M90W rear badge:

 

 

Attached File  M90W.jpg   211.97K   7 downloads

 

 

 

 

And do you guys remember the M90 that came up for sale on ebay a few years ago that had a modified battery tray to accept 12 D batteries???

 

Shown here modified. Owner said he had Radio Shack modify the battery tray to 12 D's back in the day:

Attached File  M90 BATTERY MOD.jpg   110.42K   10 downloads

 

 

And stock size:

Attached File  IMG_8568.JPG   145.01K   6 downloads



#19 caution

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Posted 12 January 2017 - 05:05 PM

18V... 15V... whatever. What's 3 volts between friends?? :lol:



#20 trippy1313

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Posted 13 January 2017 - 12:58 PM

I don't hear much about my W version. But it looks like it just has more voltage options?

#21 Superduper

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Posted 13 January 2017 - 05:20 PM

M90JW and M90C do have a different wattage rating on the speakers though.

 

C wattage on the speaker is 25W:

attachicon.gifIMG_5137.JPG

 

JW wattage on the speaker is 20W:

attachicon.gifIMG_5138.JPG

 

 

Joe, I didn't know that.  However, looking at the speakers, they physically appear identical.  I would guess that there's no real difference between them and once again, probably just a labeling/rating requirement for reasons of compliance with local regulations.  In order for one speaker to truly handle more power than another otherwise similar speaker, the voice coil windings would need to be wound with thicker gauge wire.  This usually translates to more weight, and larger voice coil.



#22 blu_fuz

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Posted 13 January 2017 - 06:39 PM

The 20 W and the 25 W speakers are physically identical in weight and size .

#23 trippy1313

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Posted 13 January 2017 - 07:45 PM

The 20 W and the 25 W speakers are physically identical in weight and size .

Interesting, I should see what mine are.

I've kind of been looking for a thread like this on the M90. I know there was one on the M70 models. I suppose we have enough here in the group to finally figure out what differences there actually are.

#24 hopey

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Posted 15 January 2017 - 06:03 PM

What about the Frequency? As the model that has the multi tap transformer (240/220/110v) and can run on 50hz means it's an upgraded power supply this should give you a boost in Output therefore the same circuitry and speakers have been upgraded (although identical). 

 

Frequency

Both 50Hz and 60Hz have their advantages and disadvantages.

60Hz

With 60Hz, the transformers can be smaller and less expensive than for a 50Hz transformer. Although the difference is small, it can add up in a system with many transformers. Using 60Hz results in less flicker on lamps, but that really is not a factor these days.

Hum and frequency noise are more readily audible with 60Hz and its harmonics than with 50Hz.

50Hz

With 50Hz, electric power transmission over long lines favors it over 60Hz. The effects of the distributed capacitance and inductance of the line are also less at the lower frequency.

Although 50Hz transformers require more copper and iron, 60Hz transformers require more expensive plates to prevent eddy current losses.



#25 Superduper

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Posted 15 January 2017 - 06:32 PM

The discussion of 50 vs 60 hz really isn't useful here because we can't choose whether our locals use 50 or 60 hz, it is what it is, but insofar as the transformers on THIS boombox is concerned, to my knowledge, both the 61 and 70 watt rated versions spec 50/60 hz.  So no difference. Even if a transformer were capable of handling more power before it overheats, the boombox must be capable of consuming higher current to be useful, and if the circuitry is the same, then the boombox's ability to consume higher current will be dictated by how much voltage it is fed.  The higher the voltage, the more current can be consumed.  If transformer x and transformer y both output 18v and both are capable of providing the min output necessary to power the boombox, AND but transformer y can handle more current, it STILL will make no difference because both x and y will output only what the boombox needs.



#26 hopey

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Posted 15 January 2017 - 07:51 PM

The discussion of 50 vs 60 hz really isn't useful here because we can't choose whether our locals use 50 or 60 hz, it is what it is, but insofar as the transformers on THIS boombox is concerned, to my knowledge, both the 61 and 70 watt rated versions spec 50/60 hz.  So no difference. Even if a transformer were capable of handling more power before it overheats, the boombox must be capable of consuming higher current to be useful, and if the circuitry is the same, then the boombox's ability to consume higher current will be dictated by how much voltage it is fed.  The higher the voltage, the more current can be consumed.  If transformer x and transformer y both output 18v and both are capable of providing the min output necessary to power the boombox, AND but transformer y can handle more current, it STILL will make no difference because both x and y will output only what the boombox needs.

 

 

I was a little off target. When you look at power ratings there are two values e.g. USA and Australia, the Australian version has a higher capacity due to the higher voltage and 50hz rating. When you have a multi tap transformer the lower voltage and frequency 110v/50hz actually benefits from the upgraded transformer. 

 

While the increase in output of the transformer seems minimal it will shift the knee point for distortion.



#27 Superduper

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Posted 15 January 2017 - 10:02 PM

I think you are adding confusion. The 50/60hz thing isn't an issue as I believe ALL of the jvc transformers are 50/60hz capable so same gauge windings plus you can't choose to feed 50 or 60hz. As far as multi-tap dual winding transformers, the secondary voltage is not supposed to vary based on input voltage if you choose the proper setting. The difference typically depends whether the primary winding is run in parallel (120v) or series (240v). Sure higher voltage has greater potential but it's pushing both windings in series which makes it pretty much equivalent to dual windings run in parallel at the lower voltage. In either case, secondaries get the same power. Bottom line is that unless you know that one transformer has secondaries with greater voltage, or that any of them are underpowered and sags on demand for the needs of the amp as installed, it would be presumptuous to suggest what will happen in any particular configuration. We are still discussing the accuracy of whether there is any real difference in the rating numbers or whether they are basically a regional numbers game. Lastly, as far as distortion point, once again you are making some presumptions here. Each chip maker publishes a datasheet and the point typically varies with voltage and output impedance. Of course these specs presume a stable power supply capable of supplying the needed current. You are presuming that the may not meet the amp needs satisfactorily. Even relying on the rating numbers themselves would be a presumption.

#28 JVC Floyd

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Posted 16 January 2017 - 01:24 AM

In my opinion no matter what the input voltage is the output wattage is always going to be the same across the board it's called quality control. JVC was aiming for uniformity of performance across the worldwide Market.

I've owned 3 m90 and I can say with confidence no one sounded louder than the other especially by 10 watts. If there was an m90 that was 10 watts more powerful than another another m90 I mean wouldn't it be logical that it would drain the batteries a lot faster.

#29 hopey

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Posted 16 January 2017 - 05:00 AM

I think you are adding confusion. The 50/60hz thing isn't an issue as I believe ALL of the jvc transformers are 50/60hz capable so same gauge windings plus you can't choose to feed 50 or 60hz. As far as multi-tap dual winding transformers, the secondary voltage is not supposed to vary based on input voltage if you choose the proper setting. The difference typically depends whether the primary winding is run in parallel (120v) or series (240v). Sure higher voltage has greater potential but it's pushing both windings in series which makes it pretty much equivalent to dual windings run in parallel at the lower voltage. In either case, secondaries get the same power. Bottom line is that unless you know that one transformer has secondaries with greater voltage, or that any of them are underpowered and sags on demand for the needs of the amp as installed, it would be presumptuous to suggest what will happen in any particular configuration. We are still discussing the accuracy of whether there is any real difference in the rating numbers or whether they are basically a regional numbers game. Lastly, as far as distortion point, once again you are making some presumptions here. Each chip maker publishes a datasheet and the point typically varies with voltage and output impedance. Of course these specs presume a stable power supply capable of supplying the needed current. You are presuming that the may not meet the amp needs satisfactorily. Even relying on the rating numbers themselves would be a presumption.


Touché.

A bigger power supply is always going to be better. Can't explain why the same speakers (part number identical) would have two different wattages printed on the magnet. These are always subject to change but can't help thinking is related to the 70w power supply.

#30 Cpl-Chronic

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Posted 28 July 2017 - 12:26 PM

This debate could be decided with a volt meter....compare the DC voltages, when plugged into the wall, between the models going to the AMP IC...BAM!!  The ideal would be a member with both models doing this, using the same wall plug exactly...That would rule out AC voltage differences between regions, supply, etc.  I hypothesize that the 100v power block of the Japan version is the same as the 120v Canadina version & the difference in AC supply voltage is the 70w difference.  Maybe CDN standards allow the use of the 100v version, maybe to save money?  Just a guess but it does seem related in some way...

 

Cheers,

Cpl