Hi,
I have a simple receiver, Denon 591.
It´s my first receiver, I bought in 2009 and it´s with me yet.
This receiver does not have pre-out channels to connect amplifiers.
The power consumption informed by the manufacture is 360W, let´s say that power at output will be around 160W after all loses and eletronic consumption.
The power supply of this receiver is 42Vav, let´s say ~58Vdc under load and only two 6800uF/75V capacitor, one each rail.
So, has enough voltage to drive higher power at the output but the transformer is small.
And is a 5 channels receiver...
So, my question is:
This receiver has some digital/eletronic limitation of power for the channels?
Or the limit will be the power supply going down when all channels are drived at full?
Because if it does not have digital limitation at the channels, I was thinking to do another power supply, with bigger transformer and more capacitors.
I thought test with a resistor in all the channels, but I will not be able to put audio in 5 channels because it does not have pre input for surround and central, just for front.
Today I measured the voltage at the front book watching Netflix and with the volume at normal level (high enough to me) the voltage was around 8~13V during normal conversation, etc... and peak of 15V, 21V and 25V.
Let´s say that 13V is in all channels, will be around 105W continuous, and peak of 390W, I did not test with all channels driving because probably the level of sound in the other channels would be different, so, I can´t confirm if it has software limitation for surround and central channel.
Maybe the best choice will be monitoring the voltage at power supply during normal use... and check how low it goes.
Thanks for the support.
I have a simple receiver, Denon 591.
It´s my first receiver, I bought in 2009 and it´s with me yet.
This receiver does not have pre-out channels to connect amplifiers.
The power consumption informed by the manufacture is 360W, let´s say that power at output will be around 160W after all loses and eletronic consumption.
The power supply of this receiver is 42Vav, let´s say ~58Vdc under load and only two 6800uF/75V capacitor, one each rail.
So, has enough voltage to drive higher power at the output but the transformer is small.
And is a 5 channels receiver...
So, my question is:
This receiver has some digital/eletronic limitation of power for the channels?
Or the limit will be the power supply going down when all channels are drived at full?
Because if it does not have digital limitation at the channels, I was thinking to do another power supply, with bigger transformer and more capacitors.
I thought test with a resistor in all the channels, but I will not be able to put audio in 5 channels because it does not have pre input for surround and central, just for front.
Today I measured the voltage at the front book watching Netflix and with the volume at normal level (high enough to me) the voltage was around 8~13V during normal conversation, etc... and peak of 15V, 21V and 25V.
Let´s say that 13V is in all channels, will be around 105W continuous, and peak of 390W, I did not test with all channels driving because probably the level of sound in the other channels would be different, so, I can´t confirm if it has software limitation for surround and central channel.
Maybe the best choice will be monitoring the voltage at power supply during normal use... and check how low it goes.
Thanks for the support.
Don't bother.
Unless you want to re-engineer the entire unit.
If you need more output power, buy a bigger unit.
Unless you want to re-engineer the entire unit.
If you need more output power, buy a bigger unit.
Units like this tend to be severely power supply limited in multichannel operation (stereo power output, by contrast, is usually OK - you might be getting 2x >100 W but only 6x 25 W or so). Possibly all the better, since they tend to run output transistors on the edge of SOA as well. Check what it uses before performing any major mods. Some units only have 2SC5198/2SA1941 on rails exceeding +/-55 Vdc.
I wouldn't bother redoing the entire power supply (quite the hassle, expensive, not even guaranteed to work since you don't know what kind of other voltages you have to generate). Squeezing in some extra 10000 µFs in parallel to the existing caps (leads twisted) may be worth it though, audio usually is more about peak than sutained power anyway.
I wouldn't bother redoing the entire power supply (quite the hassle, expensive, not even guaranteed to work since you don't know what kind of other voltages you have to generate). Squeezing in some extra 10000 µFs in parallel to the existing caps (leads twisted) may be worth it though, audio usually is more about peak than sutained power anyway.
Do you believe that it has software limitation and changing the power supply will have no effect?
Ok, as you suggested I think that does not worth waste time with the modd of this receiver.
I will assembly the boards of Dx Super A, with 35Vac maybe I can get 100W/8ohms like I read around here.
The only problem is that I will need to use my computer as pre-amp and will lost the equalizer, audissey, delay compensation of the receiver.
Do you have any ideia how to contorn this situation? (without buying an pre-out ofcourse)
I will assembly the boards of Dx Super A, with 35Vac maybe I can get 100W/8ohms like I read around here.
The only problem is that I will need to use my computer as pre-amp and will lost the equalizer, audissey, delay compensation of the receiver.
Do you have any ideia how to contorn this situation? (without buying an pre-out ofcourse)
Adding "pre-outs" for use with an outboard power amp would be easy enough, all it takes is a resistor divider per channel for about -26 dB. 22k/1k2-ish or so. If you want, you can fashion the fancy version on some perfboard, spring (or screw) terminals on one side (nothing fancy required), RCA jacks the other. A load that high basically just leaves the integrated power amps twiddling their thumbs, producing barely any distortion at all.
How exactly did you measure your output voltage again? TBH I wouldn't trust a multimeter much when it comes to displaying random AC signals, a scope is more like it. Running a voltage divider to a line-level input would be another option.
What kind of speakers are you running anyway? You can always reduce power amp loading by using more sensitive speakers or adding a powered sub.
How exactly did you measure your output voltage again? TBH I wouldn't trust a multimeter much when it comes to displaying random AC signals, a scope is more like it. Running a voltage divider to a line-level input would be another option.
What kind of speakers are you running anyway? You can always reduce power amp loading by using more sensitive speakers or adding a powered sub.
Your suggestion is to attenuate the power output of the receiver?
I never thought in this ideia.
I measure with scope the voltages.
Has anyone here saw something like attenuation by software of the central and surround channels?
If is truth, I will not be able do extract all the power from the channels.
My speakers are KEF Q100 and Q800DS, low sensibility.
Exactly.
So were they peak (from zero) or peak-peak?
Never heard of anything like that, not for the sake of limiting power anyway.
And I take it you don't have a Q400b or two to go with them?
The Q100s have a 130mm woofer, nominal sensitivity 86 dB/2.83V... the preferred listening distance for something that small would be about 1.5 m, 2 m tops, and you should be able to go even closer as they're a coax job.
With speakers like that, I reckon they'll produce a good amount of intermodulation distortion before the amplifier reaches its limit. They may be able to handle 100 W but I doubt you'd still want to listen to them beyond about 25. Like I said, don't position them too far away, ideally give them some support in the bass department (bass takes up a lot of power and causes high speaker excursion), and you should be quite happy.
Q800ds is a bit of an oddity... I haven't seen dipole speakers since the ProLogic days, not too sure why one would want to use some.
"Sensibility" is when someone is reasonable. When they are touchy, it's sensitivity. The English language is mean sometimes...
The values are peak voltage only.
I saw results about power limiting in this video when they tested a receiver: https://youtu.be/vBQ5Ub9n-OU
In this video you can check the power limit but we don´t know if is in the pre-amp stage, power stage, if depends onde the voltage at the rails, etc...
Your suggestion is the same as this converters: Conversor RCA para Som Automotivo | Connect Parts
But I don´t know if using this I will can use only the surround with independent amp, beacuse the levels will be very different.
I listen the speakers around 3m from then, the use is only for movies.
My sub is an Boston Acoustic, very simple, but I will buy another in the next future.
Sorry for the bad english.
I saw results about power limiting in this video when they tested a receiver: https://youtu.be/vBQ5Ub9n-OU
In this video you can check the power limit but we don´t know if is in the pre-amp stage, power stage, if depends onde the voltage at the rails, etc...
Your suggestion is the same as this converters: Conversor RCA para Som Automotivo | Connect Parts
But I don´t know if using this I will can use only the surround with independent amp, beacuse the levels will be very different.
I listen the speakers around 3m from then, the use is only for movies.
My sub is an Boston Acoustic, very simple, but I will buy another in the next future.
Sorry for the bad english.
Just to inform, I found the service manual of this receiver.
Will be easy to put the pre-amp output in the rear panel.
May I just take the wire from this connector and connect into my external power amplifier?
I would like to continue with the original amplifier for some channels, like surround for now.
And the possibility of quick change between external and internal amplifier if I need to fix or change something in the external power amp.
Will be easy to put the pre-amp output in the rear panel.
May I just take the wire from this connector and connect into my external power amplifier?
I would like to continue with the original amplifier for some channels, like surround for now.
And the possibility of quick change between external and internal amplifier if I need to fix or change something in the external power amp.
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What are you trying to achieve - do you need more power, or you just don't get the sound quality from the existing amplifier ?
From you voltage measurements it seems there's enough voltage to get the sound level you want ?
Another option is to modify the amplifier in your receiver. That is what I did: http://www.diyaudio.com/forums/soli...odified-pioneer-ht-amplifier.html#post4199133
From you voltage measurements it seems there's enough voltage to get the sound level you want ?
Another option is to modify the amplifier in your receiver. That is what I did: http://www.diyaudio.com/forums/soli...odified-pioneer-ht-amplifier.html#post4199133
I would like to try a better amplifier instead the original of this entry level receiver.
About the output voltage, I checked with 1kHz signal and voltage drop alot because low capacitance of supply, just 6800uF.
So, I would like to assembly an amplifier and a better one, but my receiver did not has the pre-amp output in the rear panel.
I will check your thread.
Attached you can check the circuit of one channel of this Denon AVR 591.
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That doesn't look like a bad amplifier design to me and should be capable of good results; there may be some improvements that can be made by yourself depending on the goal.
I modified my amplifier to increase the feedback factor which made for punchier bass and cleaner sound overall. But it was borderline whether the sound quality coming into the power amplifier was good enough, the DAC and signal chain before the power amplifier was a limiting factor. I also thought about making pre-amp outputs for an external amplifier but I realized that a better quality amplifier could not be justified in my case without a better DAC and signal chain feeding it. You may face the same bottleneck.
One thing to note, your receiver may have protection / mute relays on the amplifier outputs that allows the sound to be muted when the receiver is first turned on and when it is turned off to prevent weird or nasty noises reaching the speakers during power-on and power-off.
You might be able to gain some improvement a different way - by building a strong well designed external power supply and using it to feed the power amplifier inside your existing receiver. Such an external supply could be used for other projects in the future, or for any future HT receivers you own. This is something I am still considering for my own HT receiver. I would begin by looking for a large power transformer and a nice chassis to put it in; I might add a soft-start module which I'd buy from eBay for $20 or so.
I modified my amplifier to increase the feedback factor which made for punchier bass and cleaner sound overall. But it was borderline whether the sound quality coming into the power amplifier was good enough, the DAC and signal chain before the power amplifier was a limiting factor. I also thought about making pre-amp outputs for an external amplifier but I realized that a better quality amplifier could not be justified in my case without a better DAC and signal chain feeding it. You may face the same bottleneck.
One thing to note, your receiver may have protection / mute relays on the amplifier outputs that allows the sound to be muted when the receiver is first turned on and when it is turned off to prevent weird or nasty noises reaching the speakers during power-on and power-off.
You might be able to gain some improvement a different way - by building a strong well designed external power supply and using it to feed the power amplifier inside your existing receiver. Such an external supply could be used for other projects in the future, or for any future HT receivers you own. This is something I am still considering for my own HT receiver. I would begin by looking for a large power transformer and a nice chassis to put it in; I might add a soft-start module which I'd buy from eBay for $20 or so.
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I grabbed one of the 591s when they were new. They were one the better AVR's I could find in the price range in terms of sound, and the only one having audyssey calibration. With relatively efficient energy tower speakers and svs pb12 sub I wasn't disappointed with mine in terms of sound and output, even while sub was off. I recall it having just one set of preouts for heightening speakers but I never got around to trying that effect.
Bigger transformer = bigger heat sink required. Designers use underrated transformers on purpose to keep output devices from dissipating too much heat. If the going gets rough, then the power supply collapses. I have yet to see an AV receiver that doesn't do this on the bench. It works, but sometimes to the detriment of your sound.
Because of the transient nature of music, this scheme works better than you may think. I've heard it with my own ears though - bigger transformer = bigger bass.
Your idea of adding a line level output and using an external amp is the most practical solution.
Because of the transient nature of music, this scheme works better than you may think. I've heard it with my own ears though - bigger transformer = bigger bass.
Your idea of adding a line level output and using an external amp is the most practical solution.
I agree with you but it not necessary need a big heatsink.
For instance, I´m not using full power at all time, just want more power for dinamyc sound.
Attached you can see the schematic of power supply.
But in my case is just 6800uF/75V, not 12000uF like in the schematic.
I think that 12000uF is for the 7 channels amplifier, because the service manual is the same.
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Other problem that I´m facing is the fact that I bought KEF Q800DS for surround (bad idea after read about it for my room).
In my speakers disposition in the room, the surround, sound like dead sound.
For now I can't change the speakers until I sell this one, so I put more gain in this channels... but a lot more, like +7~8dB over the audissey preset, and this means more power from the receiver...
I will try to fix this with another speakers placement in the room but I have no idea right now.
I will share the drawing of my room with KEF guys and see if someone can help me.
Attached you can see a ugly drawing that I did in paintbrush with disposition of the speakers.
Anyone has some idea about it?
Thanks!
In my speakers disposition in the room, the surround, sound like dead sound.
For now I can't change the speakers until I sell this one, so I put more gain in this channels... but a lot more, like +7~8dB over the audissey preset, and this means more power from the receiver...
I will try to fix this with another speakers placement in the room but I have no idea right now.
I will share the drawing of my room with KEF guys and see if someone can help me.
Attached you can see a ugly drawing that I did in paintbrush with disposition of the speakers.
Anyone has some idea about it?
Thanks!
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You think the engineers that design these units don't know that? Heat sinks are notoriously small in consumer products. Engineers know that they can get away with it for the same reason you give.
I would at least monitor heat sink temp (remember die temp is much higher) if you go this route. You might get away with it, but you're really pushing it.
My observation is that AV receivers can't even deliver full rated power (not even close!) with all channels driven. The better ones can deliver full power with two channels driven.
Reread my post about the power supply collapsing and how it keeps the output devices within safe temps and SOA limits. This is by design! It may be cheesy, but it works.
Ok, I agree with you.
Yesterday I saw a movie and check that receiver was a little bit more than warm, if I improve the power supply this can become a problem.
I thought more about this and maybe the best choice would be do a new power supply, with more capacitance and bigger transformer, instead an external amplifier.
To use the some output circuit of receiver, with relays, mute, etc... and not do a new holes in the rear panel.
About the temperature monitoring I will see if I have some arduino and sensor without use in home. I don´t remember if I have lcd display to check the values too.
And maybe it better to run this temperature test without power supply improvements to check the temperatura rising.
About the standard circuit os Denon, anyone has some suggestion to improve it?
I checked in the service manual and the bias current suggested for it is 8,5~10,6mA.
I know a little about electronic, but I don´t know a lot about audio amplifiers to do some modifications by my own.
I checked in the service manual and the bias current suggested for it is 8,5~10,6mA.
I know a little about electronic, but I don´t know a lot about audio amplifiers to do some modifications by my own.
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