View Full Version : MOSFET! It Could Be A.... Sanyo?


wualta
01-17-2007, 01:40 AM
Next time you're sitting around talking trash with your MOSFETid friends, stump 'em with this one: "What '80s amp uses the classic Hitachi 2SJ49 and 2SK134 in TO-3 cases, two complementary pairs per channel, just like the Hitachi 8500 Mk II; dual transformers just like the Hitachi 8500 Mk II; bridgeable just like the Hitachi 8500 Mk II; 100 watts per channel just like the Hitachi 8500 Mk II; headphone jack just like the Hitachi 8500 Mk II-- but ISN'T an Hitachi 8500 Mk II? and doesn't at all resemble the otherwise similar Sherwood S-6040 CP (http://audiokarma.org/forums/showpost.php?p=471356&postcount=1)? ..Ha ha! Give up?"

http://i7.photobucket.com/albums/y285/heildriver/SanyoPLUS55mosfetamp-a_zps437503cd.jpg (http://s7.photobucket.com/user/heildriver/media/SanyoPLUS55mosfetamp-a_zps437503cd.jpg.html)
SANYO P55 MOSFET AMP

It's the circuitbreaker-equipped, LED-metered, surprisingly well-built Sanyo (yes, Sanyo, the folks who make those very reliable nickel-metal-hydride rechargeable batteries, who bought Fisher BITD and were in turn absorbed by Panasonic awhile back) Plus Series P55 MOSFET amp. About the same shape as the LED-metered Sherwood (which is also a twin-transformer design), inside they look nothing alike (nudesters to follow). In fact, the Sanyo is cooled with a heat pipe, a la Kyocera. You can hear the heat pipe gurgle when the amp's been running awhile.

Like the Sherwood, the Sanyo was on the market for a disappointingly short time and came with a matching tuner (T55) and preamp (C55). Unlike the Korean-built Sherwood, the Sanyo was a product of the home country, Japan.

The sound? Glorious. Driving a Stax Lambda Pro with the Sanyo gives the lie to the old wives' tale that electrostatic headphones don't have percussive bass. The Ultrasone demo CD never sounded so good. On the other hand, it's not much different, so far, from being a smaller Hitachi HMA8500 Mk II with LED meters and less of a brutal look. More details and impressions later. Oh, the photo shows the P55 driving a pair of damped Yamaha Orthodynamic headphones, model YH-1, with a lot of bass boost from a Yamaha C85 preamp.

The speaker selector knob shown is not original.
.

tarior
01-17-2007, 03:01 AM
I like!:yes:

redcoates7
01-17-2007, 11:51 AM
Very cool looking in a sort of SAE way...

Can't wait to see the nudies!

bully
01-17-2007, 11:59 AM
Too cool!
Looks good, too.

Damage
01-17-2007, 12:40 PM
You know, I've seen one of those in silver on CL. But the picture was so bad, I couldn't tell exactly what it was. Now I wished I had called....

sanyofreak
01-17-2007, 01:05 PM
Wualta, Cant say I sit around with any friends discussing those topics, but that is a really nice looking amp.
Thank You for confirming that the output devices were also the same used in the Hafler DH200 (I think, anyhow), also from the early eighties.
I dont know, but I have heard somewhere perhaps just through electronic industry history, that there is (was) some connection between Sanyo and Kyocera. Not necessarily true, just heard at one time in the past.
The bridgeable feature seems to me to be way ahead of its time, I cant think of too many amps that had it.
Cant say I love the look, but what a combination of technology, guts, and features, surely this product had the stuff to convert non-believers.
Cant wait to peek under the hood.
Do You also have the matching tuner and pre ????
Very nice.

Damage,
Didnt think they made these in silver - that would be a surprise.

sansui9090
01-17-2007, 05:19 PM
I am sure it sounds good,
not a pretty amp, but Mosfet sound is the BEST!!!

I have a few mosfet power amps, Perreaux, Hitachi, Hafler and a Kit Job that Really rocks.....

Nothing beats that Mosfet sound...
Enjoy!! :banana:

Mark

wualta
01-17-2007, 11:36 PM
I don't like flash-on-camera, but in this case there wasn't much choice. Some PhotoSloppery made things a little less harsh. Panasonic DMC-FZ20, macro mode, zoom at full wideangle. Note the nice even coating of dust. I don't think anyone except some long-dead weevils has been inside this thing since it came from the factory. The MOSFETs themselves hang upside down and are easily accessible from underneath, just like Sony's VFET integrateds.

Note also that while some of the parts resemble some in the Sherwood, the layout is entirely different. The heat pipe with its fins looks like something from the underside of a fridge ("WARNING: FREON GAS UNDER PRESSURE" says a sticker). Note too the unusual horizontal mounting of the power supply electrolytics (4x 10,000uF, 63v).Some of those resistors look awfully cheap and old, and speaking of that, I don't have a firm manufacture date for this amp. Does anyone have brochures or ads? This is one of those amps that turns up nearly unmentioned in Google. And that means it was probably never reviewed by one of the Big 3 audio magazines of the eighties: Audio, High Fidelity, Stereo Review. I'm going to guess the incept date as 1981, possibly earlier, based on the use of some of the earliest Hitachi devices (photos of the underside on request).

Interestingly, the back of the amp has no convenience outlets, nor does it have binding posts, just some good-quality spring clips. There's a single set of RCA inputs next to the stereo/strapped-mono switch, the reset buttons for the two 3.15A circuit breakers, and that's it.

Here's a flash shot of the fascia. Note the red anodizing of the front panel.

http://i7.photobucket.com/albums/y285/heildriver/SanyoP55a.jpg

http://i7.photobucket.com/albums/y285/heildriver/SanyoP55inside-1e-1.jpg

http://i7.photobucket.com/albums/y285/heildriver/SanyoP55inside-2e-2.jpg

This is what the speaker switch originally looked like:
http://i7.photobucket.com/albums/y285/heildriver/SanyoP55speakerswitch-a.jpg


It's hard to know what to make of this amp. It's certainly decent quality. The looks... well, you get used to the meters jumping around (they can't be turned off) and the graphics surrounding the LEDs are.. umm.. But it's certainly an alternative to the look of the Hitachi amps of the period, though on eBay the selling prices are about the same for the Sanyo and the Hitachi HMA-8500 Mk II. As for the Sherwood, I suspect that it was an attempt to build a P55 inexpensively in Korea using the later plastic bodied MOSFETs, a conventional heat sink and simpler chassis construction.

Oh, why not one more. And the Sherwood's interior, for comparison:

http://i7.photobucket.com/albums/y285/heildriver/SanyoP-55e.jpg http://i7.photobucket.com/albums/y285/heildriver/SherwoodS6040cp-1e.jpg

sanyofreak
01-18-2007, 01:02 PM
I have been inside so many vintage Sanyo receivers, I cant help but add some meaningless observations.
The horizontal mounting of the filter caps is a hallmark of how they made use of internal space, and in observation could be a consideration of the somewhat low profile of the chassis. The shields on the transformers are seen on all the plus series units I've seen, and also on pics of big Fisher receivers we've seen.(RS1060/80) However, these transfo's are Rex and all of the others I've seen on Sanyo gear have been Matsushita.

The finned bridge rectifiers are exactly the same as used in the JCX2900K and the Plus 130(also in pairs). The combination dual emitter resistors (or in this case drain resistors) are exactly those used in the plus 130's amp.
The heat exchanger (as I call it) is also exactly like the plus 130, except it is combined into one long unit on the P55. Wualta, Please give us an indication if You can heat this thing up at all,(?) that is some impressive cooling area for a 100 watt/ch amp.

Based on what I've put together on the plus series receivers, this amp should have been introduced in 1980. Service manuals from the first "JA" series amps from Sanyo are dated 1981, which came after the Plus series. I think if You search the online auctions, You will be able to find a service manual for this unit, I know I've spotted them from time to time.

The circuit breakers were used on the earlier JCX-2600K and 2900K, but not on the Plus series receivers interestingly. ( back to internal PCB mounted fuses, but cant vouch for the plus 200). They work in the event both polarity outputs short(main rails shorted), and prevent fire, but do nothing to protect the outputs themselves.
The convienience outlets were most likely placed on the C55 preamp, and the P55 and T55 could be plugged into it and switched on/off. (just a guess)...
The speaker terminals are the same used from the JCX series receivers on thru to all plus series units. They hold up very well and are some of the better ones used, but I still dont like spring clips, cant be alone there. Those LED's can be shut-off, but then what would You have to look at ????. One of the few Sanyo's that I dislike the cosmetics of.

Thanks very much for the internal pics, best of luck with the unit, chances are because of this thread, the P55 is little more sought after now, and the reasons are pretty clear.

CUlater
01-18-2007, 03:56 PM
Orion sez (replace the '7' with '8' in the years!):

SANYO
PWR, P-55 PLUS

Manufacture Years: 1971 - 1974

Power: 100

Retail
MSRP: $400.00
USED: $41.00
Wholesale
Mint: $24.00
Average: $14.00

Also listed are other members of the 'family':

SANYO
PWR, P-33 PLUS

Manufacture Years: 1982 - 1984

Power: 33

Retail
MSRP: $250.00
USED: $36.00
Wholesale
Mint: $21.00
Average: $12.00

========================

SANYO
PWR, P-75 PLUS

Manufacture Years: 1981 - 1984

Power: 75

Retail
MSRP: $450.00
USED: $62.00
Wholesale
Mint: $36.00
Average: $21.00

==============================

SANYO
PRE, C-55 PLUS

Manufacture Years: 1981 - 1984

Retail
MSRP: $300.00
USED: $32.00
Wholesale
Mint: $19.00
Average: $11.00

==========================

SANYO
SGNPRO, N-33 PLUS NOISE REDUCTION

Manufacture Years: 1981 - 1986

Retail
MSRP: $300.00
USED: $27.00
Wholesale
Mint: $16.00
Average: $9.00

=========================

SANYO
TUNER, PLUS T-35

Manufacture Years: 1980 - 1982

Retail
MSRP: $200.00
USED: $78.00
Wholesale
Mint: $45.00
Average: $26.00

===========================

SANYO
TUNER, PLUS T-55

Manufacture Years: 1980 - 1982

Retail
MSRP: $250.00
USED: $130.00
Wholesale
Mint: $76.00
Average: $44.00

Njoy!

wualta
01-18-2007, 05:54 PM
CUlater, thanks for digging all that up! You're right, Orion's fulla baloney on the dates for the P55. MOSFETs didn't even appear until the very late '70s, and the P55, C55 and T55 were all supposed to be a matching set, like luggage. So '80-'81 for the P55 should be about right.

Now, the funny thing is, Sanyo was making classic silver-face amps before they went nuts with the P55. Do a search on eBay using just <sanyo> and <amp> to get a look at what's on there now. One of 'em looks just like old Pioneer/Kenwood.

Sanyofreak, thanks for your useful comments. You identified some new (to me) heatsink styles and what they're attached to. Speaking of heat, I've been running electrostat headphones with lots of bass boost to give the amp a real phase-angle dutch rub, and it does get warm, but not as warm as the Hitachi 8500 does just sitting there. After everything's warmed up, you can hear a faint buzzing or sizzling sound coming from somewhere and you can hear a faint glug-glug sound from (I presume) the heat exchanger [Sanyo's term for it]. Tonight I'll vacuum up the dust and the dead weevils and try to pinpoint the source of the buzz/sizz.

ModernClassic
01-18-2007, 08:33 PM
Does your heatsink work properly? The coolent is still in the tube?

wualta
01-18-2007, 11:29 PM
Does your heatsink work properly? The coolant is still in the tube?
If the gurgling is any indication, yes.

I suppose I should flip the amp over and check temps directly on the TO-3s. Has anyone here had trouble with the old Freon heat-pipes in these old amps? How about heat pipe cooling of CPUs in computers?

wualta
01-22-2007, 01:13 AM
The buzz turns out to be from one of the power transformers or from its immediate vicinity. The heat-exchanger cooling system seems to be working properly, although the trickling/gurgling sounds can be a little unsettling in a quiet room. Nice gutsy typical early MOSFET sound. Drives the big Stax electrostats to ungodly volumes with startling clarity and unbelievable (for electrostats) bass.

If you had a choice between the Hitachi HMA-8500 MkII, the Sherwood S-6040 CP and the Sanyo, and assuming roughly similar selling prices, which one should you buy? Grab the Hitachi if only for the timeless styling, heavy construction, big power supply caps, big meters and servo circuits that make adjusting offset a thing of the past. Pick the Sanyo if you need something smaller and the stark aesthetics don't bother you. If you don't need the bridging feature, pick the Sherwood, which is the easiest to work on, looks good and sounds great.
.

ToddG
03-17-2007, 04:12 PM
I had a p-55 years ago. It performed very well. It did run a bit hot so I had a fan mounted on one side so it would draw cool air in. I miss it and wish I still had it.
c-ya
ToddG

Yamaha B-2
03-17-2007, 10:07 PM
Have you tried tightening the mounting bolts/screws for the transformers. Can help quiet the hum. Nice looking amp. Sanyo made one of the first high-end switching amps about ten years ago. Still considered to be one of the best around. About 18" square and 2" tall. As with most companies, when they put their mind to it, they can make some nice gear.

wualta
06-07-2007, 11:27 PM
FedEx should be bringing a breathed-upon C55 preamp. The seller says he tests and adjusts if necessary, so perhaps this one has a better than average chance of performing as it did when new (although recapping wouldn't be a bad idea, since I don't think he did that). Here's the photo from the auction of the viscera:

http://i7.photobucket.com/albums/y285/heildriver/51927724_o_e.jpg

I'm not sure which material the PCB is made of, since in the original photo it was an eye-stabbing fluorescent Tang orange.

The only thing it lacks, besides a headphone jack, is a suite of controls for phono cartridge loading. Other than that, it looks to be a good basic preamp of the era. I wonder if there are any FETs in the signal path?
.

tarior
06-07-2007, 11:55 PM
I just picked up a Plus P-55 the other day. It needs a little tinkering, but it works.

avionic
06-08-2007, 12:06 AM
I am sure it sounds good,
not a pretty amp, but Mosfet sound is the BEST!!!

I have a few mosfet power amps, Perreaux, Hitachi, Hafler and a Kit Job that Really rocks.....

Nothing beats that Mosfet sound...
I as well find the mosfet sound appealing---especially the hitachi/renesas lateral mosfets 2SK1058 and 2SJ162..:smoke:

Dave

wualta
06-14-2007, 10:56 PM
http://i7.photobucket.com/albums/y285/heildriver/sanyoc55frontslightdown.jpg

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:

http://i7.photobucket.com/albums/y285/heildriver/SanyoC55frontdetail.jpg


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.

http://i7.photobucket.com/albums/y285/heildriver/SanyoC55rackmountgrabtab.jpg
.

yrly
06-15-2007, 12:39 AM
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
06-15-2007, 12:42 AM
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
06-17-2007, 01:32 PM
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
08-30-2007, 07:18 PM
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
08-30-2007, 07:46 PM
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
08-30-2007, 09:14 PM
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
08-30-2007, 11:37 PM
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
08-31-2007, 07:51 PM
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
09-01-2007, 08:19 PM
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
09-01-2007, 08:49 PM
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
09-04-2007, 12:52 PM
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
09-04-2007, 07:31 PM
Is the AM-7040 a MOSFET amp, by any chance?

ultralc
09-04-2007, 10:09 PM
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
09-05-2007, 01:25 PM
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
09-10-2007, 02:08 PM
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
09-10-2007, 03:32 PM
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
09-10-2007, 10:15 PM
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
09-11-2007, 09:59 AM
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
11-04-2007, 02:46 PM
I like flashing lights on stereos!:D

gonzothegreat
11-11-2007, 08:15 PM
Back in October I found the Plus 55 amp and I was impressed by the solid build quality. I need to dig out my plus 55 tuner (which has its fans over at the tuner info center) and try them out with a Hitachi preamp I have sitting around.

FantasySage
11-12-2007, 04:18 AM
Yay mosfet! Gotta say i am in love with my sherwood. I kinda bought it out of the blue without knowing much about it, but damn am i glad i did. Now i just need to get the matching pre-amp (there is a tuner up on ebay)

T-800
03-06-2008, 10:07 PM
I am using an AM-7040. I like it, it's a very nice amp and has lots of power. I could take some inside pictures of mine if people still want to see the inside of one.

sejose
03-06-2008, 10:42 PM
I too have the Sanyo Plus Series P55 C55 and T55. I recently recapped the amp and now the right channel has a scratchy-staticy noise proportionate with volume. No signal, there is absolutely no noise even with the volume all the way up. I'm kind of at a loss as to where to look for the source of this noise.

Any experience here would be helpful, thanks!

Scott

gonzothegreat
12-04-2008, 08:14 AM
I have my Plus 55 amp on the bench and I'm surprised the thing worked the last time I used it. Every damn electrolytic was shot (including the 4 big ELNA caps). To check the ELNAs you need to feel the plastic tops. If you can feel a little triangle through the plastic, they're toast. Plenty of heat damaged solder joints on the driver boards as well.

Scott - The staticy noise is almost certainly a transistor issue - probably either the input diff pair or the next stage. Double check all the solder joints. FYI www.manuals-in-pdf.com has a PDF service manual for $15.

javelin79
12-04-2008, 09:20 PM
That amp is very very clean THD wise. .0009. I have 4 of them and use them strapped. The C55 Plus series preamp that matches it is one of the best preamps ever. Compares to a carver C2 easily. The are only 8ohm amps. They will not take a 4 ohm load. If one pops up on that auction site they sell for alot of money. In 1983 my grandfather bought one of those amps. They were only for sale in the US for a short time. They were then taken off the shelf. Anyway he took the amp he bought for like 329 dollars to a AMP clinic put on by hitchcock labs. Anyway they spec'd the amp and they like to have fell over backwards. It was better then any of the high end amps in the stereo store that were there at that time. Hope that helps and enjoy the amp as it is rare and very very clean.

tubeboob
01-26-2009, 05:50 PM
I also have the AM-7040 and matching Preamp AP-7020, both purchased NOS about a year ago. They sound amazing. This Amp has punch, definition, dimension, clarity . . . it's really an aural beaut/brute. The AP-7020 also is amazing, as I have tried it as a preamp with my tube amp and its clarity and delivery is very high end. These are definitely sleepers.:banana:

Additional mosfets that I have include the Sanyo P55 in silver purchased from Germany where they were available in silver, and I have the matching silver preamp. While the preamp is switchable between 220v and 110v, the amp is not. But looking at the inside of the amp, it appears that to use 110v is only a matter of switching some wires.

The amp is in need of some repair, and I just got a set of 8 2sk134 and 2sj49 NOS Hitachi mosfets. I've been looking for about 1 1/2 years to get a set at a reasonable price. Usually a pair goes for $25.00 to $30.00 plus around $5.00 to $10.00 for shipping. I got my set for $60.00 delivered.

The amp is currently in Tampa at my technician, like I said, we've been awaiting the mosfets for quite a while now, and I am looking forward to fixing it up.

As soon as I get it fixed, I shall provide an update. I always look for these mosfet amps, as they sound great, with tube amps being the only beasts that will be chosen before the mosfets.

I am looking for the Tuner and the tape processor in Silver so that I can have a matching set, but I think that will be difficult to find in the USA. I can always have a "black and silver" set??:D

Cheers

Donald

highfigh
01-26-2009, 08:26 PM
Next time you're sitting around talking trash with your MOSFETid friends, stump 'em with this one: "What '80s amp uses the classic Hitachi 2SJ49 and 2SK134 in TO-3 cases, two complementary pairs per channel, just like the Hitachi 8500 Mk II; dual transformers just like the Hitachi 8500 Mk II; bridgeable just like the Hitachi 8500 Mk II; 100 watts per channel just like the Hitachi 8500 Mk II; headphone jack just like the Hitachi 8500 Mk II-- but ISN'T an Hitachi 8500 Mk II? and doesn't at all resemble the otherwise similar Sherwood S-6040CP (http://audiokarma.org/forums/showpost.php?p=471356&postcount=1)? ..Ha ha! Give up?"


http://i7.photobucket.com/albums/y285/heildriver/P1010303e_filtered.jpg
SANYO P55 MOSFET AMP

It's the circuitbreaker-equipped, LED-metered, surprisingly well-built Sanyo (yes, Sanyo, the folks who make those very reliable nickel-metal-hydride rechargeable batteries) Plus Series P55 MOSFET amp. About the same shape as the LED-metered Sherwood (which is also a twin-transformer design), inside they look nothing alike (nudesters to follow). In fact, the Sanyo is cooled with a heat pipe, a la Kyocera. You can hear the heat pipe gurgle when the amp's been running awhile.

Like the Sherwood, the Sanyo was on the market for a disappointingly short time and came with a matching tuner (T55) and preamp (C55). Unlike the Korean-built Sherwood, the Sanyo was a product of the home country, Japan.

The sound? Glorious. Driving a Stax Lambda Pro with the Sanyo gives the lie to the old wives' tale that electrostatic headphones don't have percussive bass. The Ultrasone demo CD never sounded so good. On the other hand, it's not much different, so far, from being a smaller Hitachi HMA8500 Mk II with LED meters and less of a brutal look. More details and impressions later. Oh, the photo shows the P55 driving a pair of damped Yamaha Orthodynamic headphones, model YH-1, with a lot of bass boost from a Yamaha C85 preamp.

The speaker selector knob shown is not original.

Sanyo had a VFet amp, too. They're one of the largest semiconductor manufacturers in the world.

cutra
10-04-2010, 10:10 AM
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

They are fantastic amps!
I have 3 working ones and 2 non working ones.
Once I get my life back on track I'm going to get them all looked at to make sure they
are all good....

Andy_H
04-14-2011, 12:13 AM

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.



Reviving this thread with questions/comments on the power switch. I bought a C55 a few months ago and have been happy with it but it has developed a problem that appears to reside in the power switch - the switch certainly seems to be a trouble spot in these. With mine, when I powered it on, it started to make a crackling, sizzling sound from the pre and an awful buzz came through the speakers. Turning down the volume and changing the input did not stop the buzz so I quickly shut it off and went looking for the source of the noise.

I put it on my workbench, removed the top, and powered it on, listening carefully to pinpoint the exact source of the crackling. It seemed to be coming from the power switch, so I removed the switch and temporarily wired in a generic SPST, turned it on and no more crackling. The original switch is an Alps, labeled "Snap Switch N 53". At least I think it reads "N 53", but the print is tiny. On the top it reads "TV-5 SDU1P 940". Google didn't turn up any matches for those numbers but I did find some relatively similar looking Alps switches labeled "TV-5". I'm not sure what would be right to replace this. Does anyone know what the best replacement for this might be? Pictures:

http://www.audiokarma.org/forums/attachment.php?attachmentid=268917&stc=1&d=1302754139
http://www.audiokarma.org/forums/attachment.php?attachmentid=268918&stc=1&d=1302754139
http://www.audiokarma.org/forums/attachment.php?attachmentid=268919&stc=1&d=1302754139

Date code on mine reads "101279" so October 12, 1979, I suppose.

audio3000
09-24-2011, 09:33 PM
Mine had the same problem many months ago when I first bought it. It's a common problem on P55. I could not find a direct replacement for the power switch. So I just squeezed some dry contact cleaner thru those tiny holes on top and the problem has gone and could not hear any sizzling sound when I put my ear close to the power switch couple minutes ago.

Last week, I found two dry up 10uF caps on the current source base. Only these two were dried as my cap ESR meter showed. But I also replaced the other lower value caps. Luckily the big caps are still very good. It took couple of days to clean up the sound after the cap replacement. Then the amp runs even cleaner.

Good luck...

A3K

HOOG
01-15-2012, 11:14 PM
Andy_H - did you ever find a replacement? I have a Sanyo 2033 receiver that is exhibiting the same power switch problems. Same switch from your photo, but a slightly different mount and external resistor/capacitor. I would like to replace it with the same part, if possible. Thanks!

Andy_H
01-16-2012, 09:48 AM
Andy_H - did you ever find a replacement? I have a Sanyo 2033 receiver that is exhibiting the same power switch problems. Same switch from your photo, but a slightly different mount and external resistor/capacitor. I would like to replace it with the same part, if possible. Thanks!

Man, I had forgotten about this thread. I didn't end up finding an exact replacement. What I did was take the old switch into a local electronics shop where they have a huge bin of miscellaneous switches, dug through until I found a similar-looking one and replaced the original with that. I don't use this pre very much lately but it works fine with the replacement switch.

rnorton
01-16-2012, 03:19 PM
Sanyo Plus series gear was all very good (and usually not actually made by Sanyo).

HOOG
01-16-2012, 07:51 PM
Man, I had forgotten about this thread. I didn't end up finding an exact replacement. What I did was take the old switch into a local electronics shop where they have a huge bin of miscellaneous switches, dug through until I found a similar-looking one and replaced the original with that. I don't use this pre very much lately but it works fine with the replacement switch.
Thanks - I'll keep searching!

TimF
01-17-2012, 07:34 AM
Boy, talking about bringing back some memories looking at these pics of the Sanyo "P" series. I bought the amp, preamp, tuner and also the matching cassette deck new in 1981. The amp was very good I thought at the time, the pre and tuner were okay. The tape deck gave me a bit of problems in the transport section from day one, but once sorted, good to go.

Mine all had the rack-mount ears and it all looked very good sitting in a Sansui rack-mount upright stand. The gear was powering some 3-D Acoustics towers at the time. Loved hearing the gurgling from the cooling system in the amp once you turned everything off for the night.

One thing I also loved about this gear is that all the controls-volume/tuning knobs and switches just felt nice to operate. Decent stuff there, should have kept them, but then again, should have kept most of the gear I have had! Thanks for the pics guys, great fun! Tim

wualta
01-18-2012, 04:18 PM
Belated thanks to Andy H for giving us a closeup look at the C55's power switch problem. If I haven't mentioned it earlier in this thread, I've since read of a few owners of the P55 with power-switch problems.

This reminds me of the trouble Radio Shack was having with switchgear in its late-'80s electronics made by its own TCE (Tandy Corporation Electronics) factory in Korea.
.