Reciever power supply upgrades

Discussion in 'Archived Threads 2001-2004' started by Mathias H, Jun 18, 2002.

  1. Mathias H

    Mathias H Auditioning

    Joined:
    Jun 12, 2002
    Messages:
    4
    Likes Received:
    0
    I had a thought. (Always a bad idea)

    There are many receivers with inadequate power supplies, at least compared to the claimed amplification. It seems that most receivers can meet the watts per channel spec if only 2 channels are driven, so there is nothing wrong with the amps, only the power supplies are incapable of feeding them.

    So what is to stop someone from changing the power supply? If there is a deficient component on my computer, I pull it out and change it.

    Of course there would be warranty issues, but aside from that, is it doable? What sort of power supply would you need. What about computer power supplies - newer computers demand as much as 400-500W. And how complex is it - ie are these components modular, like in a PC, or would it require soldering - desoldering etc.
     
  2. Saurav

    Saurav Cinematographer

    Joined:
    Feb 15, 2001
    Messages:
    2,174
    Likes Received:
    0
    I think that's the crux of the problem, they're not modular like they are in PCs. Also, I really doubt if a PCs power supply would work in an audio component. I believe they have a fair amount of high frequency noise, which doesn't affect a computer at all, but would degrade audio performance. I could be wrong on this, but I think I read something about the switching noise on SMPS affecting audio applications.

    It's also not possible to simply as replacing all the capacitors in a power supply with bigger ones, because then the inrush current at power-up could blow a fuse or melt a switch or do other bad things. Then, you need to look at the power rails/wires supplying the power to the amps. I've seen the insides of high-end amps which use solid copper wires, almost thick enough to be called rods, as the supply lines. If you increase the capacity of the power supply, you might exceed what the PCB traces and cables can handle, and again, bad things can happen.

    Soldering - you might be able to get away without soldering - my CD player's power supply plugs into the PCB's using connectors similar to the ones found in computers. My tube amp's power supply is soldered to the main board. I don't know how most receivers would do it.
     
  3. RichardMA

    RichardMA Second Unit

    Joined:
    Apr 16, 2002
    Messages:
    446
    Likes Received:
    0
    Replacing a receiver power supply with one of those
    switching $20 units from a computer is...ill advised.
    If you are up to the task, you can replace the receivers
    supply with higher quality components, but it's not easy,
    there are space considerations, soldering, etc.
     
  4. Mark Tranchant

    Mark Tranchant Stunt Coordinator

    Joined:
    May 9, 2002
    Messages:
    126
    Likes Received:
    0
    Do NOT use a computer PSU. If you don't know why, don't even open your receiver. Here's the explanation:

    A computer PSU provides +/-5V and +/-12V with very high current capability. It uses switch-mode techniques to avoid a huge transformer - this tends to give a noisier power supply. Your receiver's amp section probably requires in the region of +/-40V with a lower (but still substantial) current capability; it probably also provides other voltages for DSP, display, preamplifiers etc.

    You would need to find out exactly what voltages your receiver's existing PSU produces and then build a replacement supply that replicates those voltages with higher current capability. Chances are, you wouldn't fit it in the case, and you'd have to ensure at least as good voltage regulation as the original.

    In short DON'T attempt this upgrade unless you have too much time on your hands, are EXPERIENCED with potentially LETHAL mains voltages and know the intimate details of power supply construction.
     
  5. Chu Gai

    Chu Gai Lead Actor

    Joined:
    Jun 29, 2001
    Messages:
    7,270
    Likes Received:
    1
    and also replace capacitors and no doubt other components...At least in the US, part of the problem has to do that the government has not yet, to my knowledge, mandated a standardized method for 5.1, 7.1, whatever amps/receivers power reporting. Many years ago, when all that existed was two channel, consumers faced the same problem. Creative power claims by manufacturers...peak power, instantaneous power, continuous power, and god knows what other terms there were. No standardization existed and some reported it at 1% distortion, 10% distortion, etc. Until the standards for multichannel power reporting are set and codified by the FCC, we can all expect to see more of this creative power reporting and will require that external publications measure the power using standardized methodology that's used for 2 channel reporting.
     
  6. Charles J P

    Charles J P Cinematographer

    Joined:
    Aug 19, 2000
    Messages:
    2,049
    Likes Received:
    2
    Location:
    Omaha, NE
    Real Name:
    CJ Paul
    The thing is, we all see now that manufacturers can meet the two channels driven requirements (even if only at 1,000hz) so what will happen if the governement does set mandates? Will we see mid-fi receivers rated at 30 wpc all channels driven 20-20k Hz? Or will we still see 100+ X 5 (6, 7, etc.) but a $250 sony receiver will now weigh 45 lbs? I personally would like to see both standards for two and multi channel revised and ratified and made into law by the FCC, FTC, BBB, or someone. I would like to see two channels driven, simultaniously, full bandwidth, and the same for however many other channels it has. My thing is, at the current time, receiver power delivery is probably pretty unpredictable. Its been discussed before, so most of us probably know that if we only listen with peaks of -15 to -10 below reference, we really only need 10-30 watts, depending on how efficient our speakers are. So, when a loud passage plays, does a reciever deliver 25 watts to all channels, or can it deliver the required wattage to the front soundstage and remaining power to the surrounds?
    I know from a Sound & Vision review, that my receiver cannot meet its published specs for wattage, with all channels driven at 20-20k Hz, but it can also play very demanding tracks, at and above reference if necessary with little to no distortion. Why? Well, first of all, not all of my channels get full wattage in a really loud part of a movie. Say the pod race from TPM. How you only hear surround when the pods wiz by, so, I dont have all channels driven 100% of the time. Also, the sound in that chapter is not wideband pink noise, so my receiver never has to produce 20-20k Hz at one time out of all channels for a sustained period. Also, I have all my speakers set to small. So, my receiver never has to amplify anything below 90Hz (notwithstanding the understood roll off rather than brick wall effect of a crossover). So, in the end, I have plenty of power for real world situations.
    So, I vote for honest publication of specs. We should be able to get 100 watts per channel, two channels driven. I'm not sure how I feel about the 20-20K Hz thing. Then give us a real rating like 36 watts all channels driven, full bandwidth, and then create a stamdardizedrating and give it a name that makes sense. Have it be an average number of watts that each channel can put out over a 30 second period with a standard test set created by a third party. This could be bandwidth limited pink noise in a pattern that would mimic real life sound tracks.
    So, my package might say, 100 watts X 2 (20 - 20,000 Hz) 36 watts X 6 (20 - 20,000 Hz) 8 watts X 6 (Charles J P scale). The customer would have some adjusting to do, but like many complex purchases, they dont need to understand it, only to have an unbiased party tell them what numbers are important (ie, you dont need to be a computer engineer to buy a PC, someone just needs to tell you that the the larger hard drive, higher GHz processer, higher number of RAM, higher MB for video card, etc, are the things you look for.)
     
  7. Chu Gai

    Chu Gai Lead Actor

    Joined:
    Jun 29, 2001
    Messages:
    7,270
    Likes Received:
    1
    From what I'd read in the past on the FCC's site, when it finally comes to pass, it'll be much like 2 channel specs. X watts, all channels driven, 20-20k, 8 ohm load. I guess possibilities also include X watts front, Y watts everything else...It's been a while since I've mosied on over to their site, but last I recall, tentative proposals were up for view and comment. I imagine in addition to people commenting, the major players such as Sony, Yamaha, Denon, etc. are also throwing their comments out. Hopefully the comments aren't written on the margins of $100 bills [​IMG]
    The thing is, at the present time, its in the manufacturers best interests to have things remain the same. Those who want to know the truth, will turn to publications that provide these measurements. Those who shop by numbers alone, well who knows how they'll make their decisions? A lot of people, even those that are aware of the true watts, make a decision based upon 110 vs 105 watts believing those extra 5 watts gives a tangible benefit.
    Nothing prevents the manufacturers from giving out specs in the same way they do for 2 channel...they just choose not to.
     
  8. Charles J P

    Charles J P Cinematographer

    Joined:
    Aug 19, 2000
    Messages:
    2,049
    Likes Received:
    2
    Location:
    Omaha, NE
    Real Name:
    CJ Paul
    The thing is, how does the FCC control this, because I still see 2 channel specs listed at 1kHz, not 20-20kHz?
     
  9. Chu Gai

    Chu Gai Lead Actor

    Joined:
    Jun 29, 2001
    Messages:
    7,270
    Likes Received:
    1
    give me an example of a model you're talking about
     
  10. Charles J P

    Charles J P Cinematographer

    Joined:
    Aug 19, 2000
    Messages:
    2,049
    Likes Received:
    2
    Location:
    Omaha, NE
    Real Name:
    CJ Paul
    I dont know, most sony's are still rated at 1kHz arent they?
     
  11. Michael Hurst

    Michael Hurst Stunt Coordinator

    Joined:
    May 10, 2002
    Messages:
    66
    Likes Received:
    0
    The heart of any good power supply is the transformer and it is also the most expensive component. Most AVR have very poor transformers or they are grossly underated for their task, again for cost or space reasons.

    Replacing the transformer probably isn't a wise choice since you would have to match it's voltage and size specs while increasing it's power capabilities. If you could find one it would be more expensive than the AVR it self. Most high-end manufacturers make their own hand wound transformers and keep it a closely guarded secret.

    I design RF amplifiers for a living and you can make the power/linearity specs say anything you want. Audio amplifiers are no different.
     
  12. Arthur S

    Arthur S Cinematographer

    Joined:
    Jul 2, 1999
    Messages:
    2,568
    Likes Received:
    0
    Mathias
    Half of the threads on this forum end up involving how much power is needed. People are dying to add a big separate amp to their receiver. Depending on your speakers, your room, and your listening habits, something like a Denon 3802 might well be enough. Subwoofers have taken a great demand off the need for power. If you really wanted a receiver with lots of multi-channel power, a step up to the Denon 4802 will get you there. Then there are the flagships that weigh 64 pounds, most of it power supply. But then you are talking $1750 and up, (Pioneer Elite 47TX).
    Artie
     
  13. Ted Kim

    Ted Kim Stunt Coordinator

    Joined:
    Apr 11, 2002
    Messages:
    214
    Likes Received:
    0
    replacing the power supply is certainly doable. You have to get a quality unit, maybe a toriodal power supply such as from Plitron or Hammond. However, in a receiver a significant limitation is probably space to put the new transformer.
     
  14. Mathias H

    Mathias H Auditioning

    Joined:
    Jun 12, 2002
    Messages:
    4
    Likes Received:
    0
    This thread certainly taught me a little about why most don't try to upgrade their power supplies. I suspected it might be more complex than in a PC.
    In reply to Arthur S, I really don't find I need more power than I have. I have had my Yamaha RX-V630 for about 2 months now, and I love it. I have yet to feel I am about to run out of gas. Now, there have been several posts that mentioned a 28w/channel test in 6ch stereo mode, and it got me thinking. If it were a $100 part and a fairly simple upgrade, I might do it when the warranty expires. Otherwise, if I feel I need more power, I will just get a good 2 channel amp and use the pre-outs for the mains. But I doubt it. Maybe if I spent more time playing all channel pink noise...but in all realistic situations it probably couldn't be distinguished from a receiver capable of driving 6x75w.
    Also, my home theater audio setup was my 1st anniversary present from my wife, and she would kill me if I cracked open the most expensive component and Tim Taylor'ed it. [​IMG]
    Yamaha RX-V630
    Energy EXL-16 mains
    EXL-15 surrounds
    EXC center
    S8.2 Sub
     
  15. Chu Gai

    Chu Gai Lead Actor

    Joined:
    Jun 29, 2001
    Messages:
    7,270
    Likes Received:
    1
    Charles JP: this was taken from Sony's site for the TA-N9000ES.

    115 watts per channel x5, 8 ohms or 4 ohms, 20 - 20 kHz, 0.013% THD
    200 watts x2, 8 ohms, 1 kHz, 0.013% THD

    so not them.
     
  16. RichardMA

    RichardMA Second Unit

    Joined:
    Apr 16, 2002
    Messages:
    446
    Likes Received:
    0
    If specifications met with any real criteria, a 100wpc Kenwood receiver would drive speakers the same way a 100wpc Bryston amp would.
    It can't. [​IMG]
     

Share This Page