# amp gurus, I have a question



## tyroneshoes

Can you tell what type of power to expect from an amp by internals? If so, can I get an estimate pls? If you need better or more more pics let me know. It has 4 25amp fuses.


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## schmiddr2

Comparing it to other es amps specs I guess 200x4 at 4. Might ask envisionelec or some others.


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## sonikaccord

It looks like it can put out that much...each of those transistors are rated at 150w so when you take in losses and the fact that they aren't running at max it should put you around 200wpc.


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## tyroneshoes

Cool. I was expecting at least double the 75x4 it was rated for so good new for me. certainly felt much more powerful than the rated specs. Thanks guys


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## envisionelec

I'm only commenting because you asked me to...

The amplifier is rated at 75W x 4 at 4 ohms and 0.04%THD. The amplifier is 0.5 ohm stable, but only for channels C/D. It accomplishes this by paralleling the output devices via relays. So rather than being "bridged", the channels are paralleled in mono mode. 

The outputs are interesting devices. They're MosFets rated at 100V and 70A; a great combination. The rails are +/- 28V in "high voltage" mode. This gives you ~150W into 4 ohms.

You can see where this is going. 

At 2 ohms and in "high voltage" mode, you're still at 28V rails so ~250W per channel (that's 250W x _4_) is not unrealistic when playing music (as opposed to test tones). 

At 0.5 or 1 ohm, the amplifier should be switched into high current mode, because you will almost certainly reach an overcurrent situation quickly at 28V rails. When switched into high current mode, the amplifier halves its rails to 14V so as not to trigger an overcurrent situation. So you're limited to the _same amount of power_.

So what's the point of having the 0.5 and 1 ohm capability if you don't gain anything? It's partly marketing. People see that and think "superior amplifier" when it's more "bait and switch" and "LOL..." to us engineers. You aren't gaining anything but flexibility, which is valuable in its own right - but don't go changing your woofers just because it can drive 'em.
The other part is stability. The output transistors can't drive sub 1 ohm loads without blowing up, so Sony implements some extensive overcurrent circuitry to force you to switch into another, lower voltage mode.

"High current" sounds better than "low voltage", but it's the _same thing_ in power supply engineering-land. 

Another thing - there is a sh*tload of SMD circuitry under that "sparse" board. It always kills me when some chucklehead opens a Japanese amplifier on AmpGuts.com and comments on the low parts count. 

It's a solid amp. If it wasn't so huge, I'd have no problem owning one. I bet it sounds divine.


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## tyroneshoes

Thanks for the reply. Very educational and makes me even more confident about using this amp as a 1 amp solution.

So it will be powering my 4 ohm comps passive on a&b (150 watts give or take a bit?) and a single 10" idq dvc4 at 2 ohms bridged on c&d.

Specs say both are stable at 2 ohms bridged (hi volt/current) I would just loose a little power going to high current but be easier on the amp. 

So at bridged 2 ohm on c&d I should be seeing around 500 in high voltage and about 300-400 in high current if Im following you.

Suppose I will try high voltage and see if it gets hot, then if so, switch to high current on the sub channels.

Let me know if I have this confused and thanks again, I appreciate it


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## envisionelec

tyroneshoes said:


> Thanks for the reply. Very educational and makes me even more confident about using this amp as a 1 amp solution.
> 
> So it will be powering my 4 ohm comps passive on a&b (150 watts give or take a bit?) and a single 10" idq dvc4 at 2 ohms bridged on c&d.
> 
> Specs say both are stable at 2 ohms bridged (hi volt/current) I would just loose a little power going to high current but be easier on the amp.
> 
> So at bridged 2 ohm on c&d I should be seeing around 500 in high voltage and about 300-400 in high current if Im following you.
> 
> Suppose I will try high voltage and see if it gets hot, then if so, switch to high current on the sub channels.
> 
> Let me know if I have this confused and thanks again, I appreciate it


2 ohm bridged will necessitate the high current mode. It won't get "too hot", it will just illuminate the "over current" LED and shut down. That will be your clue. 

500 in high voltage at 2 ohms. 500 in high current at 0.5 ohms. That's the breakdown. Going to a lower impedance gains you nothing (unless, of course, you already have the woofs) - then its flexibility saves you $$$.


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## tyroneshoes

Thanks i already have the dvc 4 idq 10".
in high current bridged to a 2 ohm sub I should get 300+ since its a one ohm load for the amp correct?
Thanks again
Makes me wish had dvc 2 but should be enough power either way


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## envisionelec

tyroneshoes said:


> Thanks i already have the dvc 4 idq 10".
> in high current bridged to a 2 ohm sub I should get 300+ since its a one ohm load for the amp correct?
> Thanks again
> Makes me wish had dvc 2 but should be enough power either way


Not quite. Because the amplifier (set to mono) puts the channels in _parallel_ and not _bridged_ mode, a 2 ohm mono load is *2 ohms*. So unless the amp has a problem with it, put it in high voltage mode and get all 500W.


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## tyroneshoes

envisionelec said:


> Not quite. Because the amplifier (set to mono) puts the channels in _parallel_ and not _bridged_ mode, a 2 ohm mono load is *2 ohms*. So unless the amp has a problem with it, put it in high voltage mode and get all 500W.


You are the man.

Thanks once again


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## Del00

Just registered because I keep looking around for another or at least a place that can repair it, and I continually come across these forums.

I have one of these, purchased brand new over a decade ago, and have been looking for a place to get it repaired (it continually blows transistors).

Just to add to the discussion if anyone cares, before it began blowing up it was powering 2 JL Audio 12W7s. It was LOUD. I don't want to get rid of this - if anyone can point me in a direction I'd appreciate it. This amp is worth every penny.


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## bigdaddy'76

Del00 said:


> Just registered because I keep looking around for another or at least a place that can repair it, and I continually come across these forums.
> 
> I have one of these, purchased brand new over a decade ago, and have been looking for a place to get it repaired (it continually blows transistors).
> 
> Just to add to the discussion if anyone cares, before it began blowing up it was powering 2 JL Audio 12W7s. It was LOUD. I don't want to get rid of this - if anyone can point me in a direction I'd appreciate it. This amp is worth every penny.



Look up MattR on this forum. He's the guy I'd talk to!!!


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## WhiteLX

envisionelec said:


> Not quite. Because the amplifier (set to mono) puts the channels in _parallel_ and not _bridged_ mode, a 2 ohm mono load is *2 ohms*. So unless the amp has a problem with it, put it in high voltage mode and get all 500W.


I've got one of these running a pair of 4ohm JL 10w1s in parallel. Would it be wise to run it in high power mode? It's been chugging away for a number of years in high current mode. 

It should go into protection before damaging the amp correct?


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## tyroneshoes

Id keep it in high current mode as those subs dont need any more power and Ive noticed the amp runs hot with a 2 ohm load in hi volt mode. 

But yes, it will go into shutdown and the amp will not be damaged so give it a shot, its safe.


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## envisionelec

WhiteLX said:


> I've got one of these running a pair of 4ohm JL 10w1s in parallel. Would it be wise to run it in high power mode? It's been chugging away for a number of years in high current mode.
> 
> It should go into protection before damaging the amp correct?


Yes, it should. The amplifier has quite a robust protection circuit. As long as you've got the charging system and power connections, the amp will happily let you know there is a problem _before_ it flips its lid.


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## Dr_jitsu

Oops, sorry, accidentally hit the "send to dumb Q forum. My Bad.


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## Popimp _8

Lil late in the conversation but I have this amp and its been a paper weight sadly snuff but it keeps popping fuses or burning the wires hooked to it Red hot ouchie lol


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## TrickyRicky

Popimp _8 said:


> Lil late in the conversation but I have this amp and its been a paper weight sadly snuff but it keeps popping fuses or burning the wires hooked to it Red hot ouchie lol


I can repair it for you. Am currently replacing thr output fets on a members 7547. Pm me if interested.


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## WhiteLX

Very timely that you bumped this back up. My 7547 just failed. I had the volume very low and all output stopped. I popped the trunk and smoke was coming from the left side of the amp. Once I pull it out and open it up, I'll send you a PM TrickyRicky.


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## SpecV

I can say Ricky has been a pleasure to work with and just got notification that my big red is ready to begin it's journey home! The wait for parts is excruciating but he found a good supplier so the price was minimal.


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## TrickyRicky

SpecV said:


> I can say Ricky has been a pleasure to work with and just got notification that my big red is ready to begin it's journey home! The wait for parts is excruciating but he found a good supplier so the price was minimal.


I listen to it for about 2-3hrs straight after repairs. Its been shipped and you should get it tuesday or wednesday.


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