MOSFET! Could It Be A.... Sanyo?

[wualta]

The seller must've gone over it with contact and pot cleaner, because all the controls are smooth and noiseless.


Here's another photo that clearly shows the front panel's unusual color:

Caveat #1: Turns out that many of the C55s up for auction either have nonfunctioning power switches or none at all. My seller actually replaced the switch on this one. Odd thing to have as a bad part, but there you are. Not a dealbreaker, but it makes you wonder.

Date sticker on the bottom of mine says 091179, which probably indicates an early one.

Does it sound amazingly great? Not particularly, but it is good. A thorough recap job would undoubtedly benefit this old dear. 1979 is starting to seem like ancient history.

Caveat #2: Sometimes the C55 is offered with rack-mount ears which have little grab tabs rather than handles (see below). Rack-mount electronics often have had the rubber feet removed, which may or may not be a good thing.

 

[yrly]

For the record there are some internally similar Sanyo integrated amps floating around as ordinary BPC usually they're part of what were bundled rack systems, and you'd never ever guess by looking at the front. Generally they'll have trannies more like the Sherwood and usually use 8200uf caps in various configurations, some with standard heatsinks some with these fin jobs. I even picked up a late 80s "receiver" that looks like a seperate tuner/amp sporting a decent amp design, much better than standard 80s BPC.

My advice is you see any Sanyo integrated amp, regardless of how much it might be ugly or look like BPC peer inside the hood before dismissing it, there are some really nice hefty designs floating around as late as 1988 models or so. Just don't plan on having a looker. I've got a nice 100wpc integrated job sporting a dual mono design that looks so much like typical BPC you'd never even have given it a second look had you seen it at the thrift. Sliding 5 band EQ, power button, sliding volume control. For whatever reason I picked it up and it weighed a hefty amount for gear of that era. Saw two big heatsinks running the length of the unit and bought it. Inside dual mono, discrete outputs and otherwise a good design in a crappy looking case.

My guess is Sanyo found it cheaper to recycle designs as opposed to building total junkers, so it worked out for the better.

 

[tarior]

I have to agree with you about some of the Sanyo integrated amps. The look like ass (not even a nice one at that) on the outside, but have some very beefy build quality and sound quite good.

 

[VOT]

I have the referenced Sherwood amp. I thought the weight belied the flimsy case but I only bought it because it said PUSH-PULL MOSFET on the outside. I think mine has an intermittent speaker connection on the SPEAKERS 1 but SPEAKERS 2 works fine. I have not played it in a while but remember good sounds from it. Thought about selling it but shipping would be so expensive given its weight, I would probably only get about $20 as-is. Oh, and it has no feet, so it's a MOS-FET NO-FEET I guess. Oh, and those stupid spring clips. What were they thinking? It looks best with the lights low and the meters on. I should give it another play. I remember the top grill gets HOT!

 

[TKO1]

Hi Everyone,

just stumbled across this thread and found it very interesting as I own the complete Plus Series system. And to this day the Plus P55 has incredible specs and great sound. I bought the complete system in November 1982 and paid around $2800CAD for it at that time. I have all the original manuals, boxes, etc. as well if anyone needs to know any of the specs etc.

The complete system is as follows:

Plus P55 Power Amplifier
Plus D64 Cassette Deck
Plus T55 Tuner
Plus N55 Noise Reduction Adaptor
Plus C55 Preamplifier

I have been using it since 1982 with various loud speakers from Infinity, Acoustic Energy, Pioneer, etc. and I am still a huge fan of this amplifier. I only use the Amp and the Preamp right now. The other three components are in their boxes in the basement storage room.

Just to give you an idea of the specifications for the P55:

Continuous power (at 8 ohms) (Normal) 100 watts x 2 (0.009% distortion)!!
(Strapped) 200 watts (0.03% distortion)

Intermodulation distortion (60Hz:7kHz - 4:1) (Normal) 0.009% (100W output, 8 ohms)
(Strapped Mono) 0.03% (200W output, 8 ohms)

Transient response: Slew rate (Normal) 150V/usec

Damping factor: (Normal) 60 (at 1kHz, 8 ohms)
(Strapped Mono) 0.7V/47 kohms

Frequency Response: (Normal) DC-100kHz (+0dB, -1dB) (1W output, 8 ohms)!!
(Strapped Mono) DC-100kHz (+0dB,-2dB)

Signal to noise ratio: (Normal) 110dB!!

You can put these specs up against a lot of the new amplifiers in the high fidelity arena and it will stand up quite nicely.

If you can pick up a working one on eBay for the ridiculously low prices I have seen claimed go for it.

Cheers.

Tony

 

[Saint Johnny]

I wish I could remember where I saw one of those Sanyos. But, I know I've seen one in the flesh. I just can't recall where, for the life of me. But I do remember thinking. How can such I nice piece of gear really be a Sanyo?

 

[ManFromPorlock]

However, these transfo's are Rex and all of the others I've seen on Sanyo gear have been Matsushita.

Something else a little peculiar about those transformers; I've never seen the particular font used on their labels anywhere except on Soviet products, before now. Any chance they're Russian-made?

 

[wualta]

Hi, Tony, and thanks for posting the specs on the P55. Very impressive-- just a few years earlier, the P55 would've been considered a superamp.

Do any of the printed materials you have say anything about the (for lack of a better term) philosophy behind the circuitry in the P55 and C55? Were they shooting for stability, waveform fidelity, transient capability, small-signal linearity.... and does the C55 have any FETs? Any circuit descriptions?

And VOT: My Sherwood also has the dodgy speaker-selector push buttons. 1's bad; 2 works.
.

 

[TKO1]

Hi, Tony, and thanks for posting the specs on the P55. Very impressive-- just a few years earlier, the P55 would've been considered a superamp.

Do any of the printed materials you have say anything about the (for lack of a better term) philosophy behind circuitry in the P55 and C55? Were they shooting for stability, waveform fidelity, transient capability, small-signal linearity.... and does the C55 have any FETs? Any circuit descriptions?

wualta,

no nothing like that. These are just bilingual (french/english) Instruction Manuals.

In the Plus C55 manual there is a section describing the:

"Tone control and subsonic system

The preamplifier provides a choice of three turnover frequencies for both the bass and treble controls. The 400Hz (bass) and 2.5kHz (treble) turnovers yield conventional tone control operation. The 100Hz and 10kHz positions modify only the upper and lower frequency extremes and are ideal for correcting high or low frequency response rolloff in a speaker system. The 200Hz and 5kHz turnover points provide an intermediate range of control.
The tone defeat switch gives an instant "flat" response for comparison with the corrected response. Similarly, the 12dB/octave subsonic filter is passive in design to eliminate distortion. Its cutoff point is switchable to 15Hz for most applications, or to 30Hz for severe cases of record warp, acoustic feedback, disc flutter rumble, or other subsonic noise problems."

and the:

SPECIFICATIONS

Input sensitivity and impedance
PHONO (MM) 2.5mV/47 kohms
PHONO (MC) 0.1mV/100 ohms
AUX/TAPE 150mV/47 kohms

Phono overload level
PHONO (MM) 250mV RMS (at 1kHz)
PHONO (MC) 10mV RMS (at 1kHz)

Output level
PREOUT 1V/600ohms
TAPE 1 REC/TAPE 2 REC 150mV

Frequency response
PHONO +/-0.2dB (RIAA 20Hz - 20kHz)
AUX/TAPE +/-0.3dB (20Hz - 20kHz)

Tone control response
BASS +/-10dB max. (at 100Hz)
TREBLE +/-10dB max. (at 10kHz)

Bass turnover frequencies 100/200/400Hz
Treble turnover frequencies 2.5/5.0/10kHz
Subsonic filter
Cutoff frequency 15/30Hz
Slope -12dB/octave

Signal to noise ratio
PHONO (MM) 85dB (at 2.5mV)
PHONO (MC) 70dB (at 0.1mV)
AUX/TAPE 100dB

Total harmonic distortion
(20Hz - 20kHz, output level at less than 3V) 0.003%"

Hope this helps. Cheers.


Tony

 

[wualta]

Thanks! Good specs. I'll have to try an MC cartridge on it someday and really wring it out, noisefloorwise.

Too bad they didn't tout the circuitry in the owner's manual. We look down our noses at marketing as mere marketing, but if a company doesn't do at least a little bragging and a little jumping up and down, we figure, "Why should we get excited?" When you've made something good and you want people to know it and then buy it-- especially back then-- you've got spend some money to toot a few horns.

Unless you've already blown the entire budget making the thing.

 

[silverlord]

Good info here! Has anyone used the Sherwood AM-7040? I have been using this amp for a few years now and find it highly musical.I paid 100$ for it a few years ago and it has been flawless.A good amp for little cash.Anyone else got one?

 

[ultralc]

I have the Sherwood AM-7040 and matching preamp AP-7020. It is a nice sounding combo. The amp is more powerful and has much bigger power transformers than the Sanyo discussed here though.

 

[wualta]

Is the AM-7040 a MOSFET amp, by any chance?

 

[ultralc]

It is. 4 pairs of outputs per channel, not sure what they are though, since each channel has two heat sinks back to back and the outputs are in the tiny space in between.

 

[wualta]

If you're in a position to take photos, and even better if you also have brochures and/or a manual, start a new thread and we'll examine this interesting beastie in detail. Sounds like a candidate for my MOSFET Room (Where Difficult Loads Go To Be Driven).

 

[ultralc]

I should have taken some photos when I had the cover off to adjust DC offset when I first got it a few years ago. Now it is under a pile of other things and itself weights somewhere between 55 and 60 lbs, it would be a major undertaking to get it out there again. Good thing is that it runs cool, so stacking other stuff on top of it is not a big concern other than the weight. Don't have any brochure either, but do have a manual, however, it is so plain and boring that it doesn't even mention MOSFET except for the graph showing the front panel controls!

 

[silverlord]

I can probably get my AM-7040 out of the rack and take some nudies of it. It is really well made and I think people will be impressed when they see it. And it is still cheap on Ebay!!

 

[wualta]

Well, you two have sold me!

No fair any lurkers reading this going off to those nameless online auction sites and bidding big money on the next good one-- it's mine, mine, mine!

Yeah right. [EDIT, 11-11-07: Hey! It is mine! More when it arrives....]

Seriously, I've managed to catch some glimpses of this amp on the intarwebb, and it's impressive in a very unSherwoody way. It does remind me of the effort Sanyo put forth to build the Plus Series, and like the Realistic STA-2200 and the Sherwood S-6040 CP, it was built in Korea. Interesting. I wonder which output devices it uses, and whether it's any relation to the ES Sony MOSFET efforts of the same era.

Of course, if you two should come up with photos, brochures, etc, quietly post 'em here. Sssshhhhhh! and thanks for making me aware of this very interesting amp!
.

 

[silverlord]

I'll try to pull it out tonight and see what the output devices are. It is definitely Un-Sherwood like.Very impressive unit.

 

[RaymondLeggs]

I like flashing lights on stereos!