Inside Yamaha amps

[SacreDro]

That sounds to me like plenty. I have a pair of ATC SCM19v2, not the most sensitive ones, and they go loud with the A-S1000 and 1200. Not saying that there aren't speakers that need more for loud listening, but they should be rare. How much power do you think one needs?

@SacreDro since you are concerned with long term stability, consider the R-S700. Digital source selector and volume knob, these are the first parts that usually go bad if they are not of the highest quality. I haven't seen a A-1000 in a decade or so that didn't have some kind of damage.
The A-S1000 should be fine however.
The A-S300 to 801? Not so much.

R-S700 isbthe same as A-S700 with minor differences from what I researched.
Found a Yamaha A-1000 mind condition as stated by the seller and from the photos is looks good for around 400-450ish $, the A-S1000 around 600 $, the AX-900 around 350 $.
The vintage ones like the CA-1000 are hard to find and expensive now and older parts are hard to find and replace in case transistors go out, matching them like in the factory is difficult, so unless prices drop newer ones are the ones to go for.
Seems to me like Yamaha until the late 80s are the best ones, not too old and parts can be found more easily, newer ones only if sold for a decent price.

 

[Deleted member 48726]

Yamaha P7000S

I got a new one to the collection. Because, well it was too good an offer to let go. This unit is from 2015 but has never seen use of any kind and has been sitting in the original packing incl. tamper screens for speaker plugs and attenuators since then. Quite a find I think.
Sounds good and looks good. Haven't had time to dive into the service manual and diagrams yet. The fans start at > 50 °C which might never happen in my use case. Don't know the peculiar thing in the specs. that drops the power from 2x700 W @ 8 ohm to 2 x 650 W for the European model. It's a switch mode power supply with ordinary A/B amplifier section. Yamaha calls it EEEngine. Similar to that of my P3200's. The p3200's have toroidal transformer though and make use of tracking the signal to supply needed voltage. Comparing the looks the older P3200 looks better to my eye. With the rack mounts removed this looks fine as well but I like the black industrial look of the older ones better.
Build quality is also not quite as good on the P7000S from a structural point of view. Thinner metal and not as much care to detail in my opinion.

Here are some measurements done to the P7000S' little brother, the P3500S. Results look good!
P3500S measurements (French, use Google translate)

Yamaha P7000S

 

[TheBatsEar]

Awesome and appreciated. Added to the index in the second post.

Impressive specimen, BTW.

 

[Deleted member 48726]

Awesome and appreciated. Added to the index in the second post.

Impressive specimen, BTW.

Thanks. Have set it up proper with my new SVS PB2000 and Dirac Live this morning. Even crossed over at 80 Hz I got the fans to spin after 20 minutes with not-so-nice SPL. But that is probably gonna be a rare sight. My ears won't tolerate this test session again anytime soon, if ever..

 

[Deleted member 48726]

Can't seem to edit my post for some reason?
P7000S with the handles removed and some feet it could easily be mistaken by a "residential" unit-->

 

[TheBatsEar]

Can't seem to edit my post for some reason?

I think you need a specific amount of posts before you can do that. Seems to be really high.

View attachment 257022

PREHISTORIC PANTHERS!

 

[mhardy6647]

PREHISTORIC PANTHERS!

The Panther

The panther is like a leopard,
Except it hasn't been peppered.
Should you behold a panther crouch,
Prepare to say Ouch.
Better yet, if called by a panther,
Don't anther.
- Ogden Nash

 

[Deleted member 48726]

The Panther

The panther is like a leopard,
Except it hasn't been peppered.
Should you behold a panther crouch,
Prepare to say Ouch.
Better yet, if called by a panther,
Don't anther.
- Ogden Nash

LOL! Thanks.

 

[Deleted member 48726]

Supplementary info IR to the Yamaha P7000S' 50 Watts lesser rating for EU an Japan models:

This is due to obey the legislations IR to power factor. There are installed two coils in series with the line power supply. These are causing the DC supply voltage to the output channel boards to drop a bit. Some have modded the amp and gone and removed the coils and shorted the two pins on the supply board and measured more output power than before.

Links to modded amps:
Yamaha P7000S modified and tested on 4 ohms
https://maurmun.com/2015/11/22/the-yamaha-p7000s-power-amplifier/

 

[mhardy6647]

That is fascinating.
(both the requirement and the workaround -- sort of like automobile owners in the US working around the seatbelt interlocks of 'way back when)

 

[audiofooled]

Supplementary info IR to the Yamaha P7000S' 50 Watts lesser rating for EU an Japan models:

This is due to obey the legislations IR to power factor. There are installed two coils in series with the line power supply. These are causing the DC supply voltage to the output channel boards to drop a bit. Some have modded the amp and gone and removed the coils and shorted the two pins on the supply board and measured more output power than before.

Links to modded amps:
Yamaha P7000S modified and tested on 4 ohms
https://maurmun.com/2015/11/22/the-yamaha-p7000s-power-amplifier/

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I wonder about any real benefits in doing this, but great post anyway

This is nothing in comparison to my DSP a1000. For the European model, there are various L, C, R and D components on many of the PCBs and it's the only model that has resistors and capacitors on the board where speaker terminals are (other models having just coils). Specs for different models are so over the place for different requirements and measuring methods, its funny to say the least.

 

[Deleted member 48726]

That is fascinating.
(both the requirement and the workaround -- sort of like automobile owners in the US working around the seatbelt interlocks of 'way back when)

Yeah, I came to think of car engines and the introduction of EGR (exhaust gas recirculation) to abide the new NOx emission legislations back in the day. The valve recirculated an amount of exhaust gas back into the cylinders to cool the combustion and thus lowering high temperature NOx formation. It lowered performance considerably at the time because of the quite crude implementations by the manufacturers. The technology wasn't good enough at the time to avoid the performance loss. There was a huge market in fitting blinding plates in the piping system and electronic boxes later to cheat the engine management system.

IR to the amplifier I don't have the need for anything near the power it is capable of, so no tampering is done on my part. I also don't know how effective the coils are in correcting the factor or how bad the cos-phi is without them. Without knowing this, I will not change anything.

SMPS amplifiers must be capacitive loads and "traditional" transformer amplifiers must be inductive loads. Interesting to investigate how badly it affects the power factor. -But all of this is quite off-topic.

 

[Yamaha 5000]

R-S700 isbthe same as A-S700 with minor differences from what I researched.
Found a Yamaha A-1000 mind condition as stated by the seller and from the photos is looks good for around 400-450ish $, the A-S1000 around 600 $, the AX-900 around 350 $.
The vintage ones like the CA-1000 are hard to find and expensive now and older parts are hard to find and replace in case transistors go out, matching them like in the factory is difficult, so unless prices drop newer ones are the ones to go for.
Seems to me like Yamaha until the late 80s are the best ones, not too old and parts can be found more easily, newer ones only if sold for a decent price.

 

[TheBatsEar]

Sweet pic, @Yamaha 5000. Welcome at ASR

 

[Willem]

I bought a 2x250 watt P2500s for my son on the basis of the French test of the P3500s. It is doing fine, is all I can say, and that for only 300 euros. I don't think the fan has ever come on.

 

[Yamaha 5000]

Sweet pic, @Yamaha 5000. Welcome at ASR

I should have mentioned that the photo is of my Yamaha CA-1000 completely restored.

 

[Yamaha 5000]

Just a few more photos:

 

[3125b]

They sure hate cable management.
On the old amps I kind of get it, single-sided PCB and all manual routing, it can get messy especially if the circuits are not completely overhauled with each new fix, feature or generation.
But on current models I really think they should do better.
Where I work part of what we do are specialty electronics, a couple dozen or sometimes hundreds of units of any given product over it's entire production run, and there sometimes products go into production that aren't completely optimized because we don't have the time or it's just not worth it.
But they make tens of thousands of these things, and then an ounce of prevention is certainly worth a pound of cure.

 

[TheBatsEar]

I don't have anything to take apart right now except for my A-S1200, and that is used daily.
Maybe at the weekend.
View attachment 227514

Thinking about it, i haven't opened my A-S1200 yet. It#s in use, what can i say except that i'm sorry.

However, look what i got yesterday for 100€ and an hour in the car:

Seller said it worked a year ago. He had it powered up, there where LEDs instead of old lamps in there, so i'm not sure what to expect inside. Contacts and potis might need some work. This is not the original pic but mine looks the same or even better. Sadly it's not silver.
Expect pictures soon

 

[Yamaha 5000]

My Yamaha MX-630 power amplifier.
2x125 W @ 8 ohm
2x150 W @ 6 ohm
Dynamic power @ 8 / 6 / 4 / 2 / 1 ohm = 175 / 220 / 290 / 390 / 420 W
Thought that I might take it apart and adjust idle now that I have taken the other apart as well for this thread.

It is the amplifier I've had for longest. I bought it when I was 13 or 14 I think. That would make the year of purchase around 1998. It is great. It may look a bit cheap on the inside but the abuse it has taken during my teenage years is insane. Never a problem with it. Doesn't even get much warm. It has even been used for a passive 15" subwoofer on just the one channel for years and also for mid / tops at a mobile disco for some multiple gigs when a pro amp burnt out. I have never seen the clipping lights in this thing!

Now it resides as a pensioner in the not-used-gear room.

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I have one MX-630 and two MX-830, what items would be recommended to refurbish them?