The Two Channel Advice Thread

Discussion in 'Advice Threads' started by purr1n, Nov 10, 2016.

  1. fastfwd

    fastfwd Friend

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    If it's important to you for the attenuator to be built with fancy audiophile resistors -- or if you're the sort of person who already has appropriate resistors at hand -- then yes, just wire up a couple of L-pads.

    Otherwise, a search for "speaker level attenuator" will probably turn up something suitable. I found this adjustable thing that's rated for 100W and presents an 8 ohm impedance, but I'm sure there are many others: https://www.parts-express.com/parts...attenuator-100w-stereo-1-shaft-8-ohm--260-264
     
    Last edited: Oct 9, 2020
  2. Metamodern

    Metamodern New

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    This might be a dumb question but I am wondering if putting my floor standing speakers on a 2 inch thick wood or marble platform would affect the sound? The floor is carpeted, however I can certainly feel vibration in my feet 7ft away at the listening position.
     
  3. bixby

    bixby Friend

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    most likely
     
  4. Armaegis

    Armaegis Friend

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    Are they currently floating on the carpet or are there feet/spikes? As a general rule, you want them more stable. Putting a platform underneath sometimes makes them less stable. Just give it the ol' nudge test. Press it with your finger, can you feel it move or rock back & forth? Then put it on a piece of plywood or whatever and try to nudge again. The "better" option will be the one that moves less. The exception here would be if the sweet spot was too low and the platform brings it up to where you need it.
     
  5. Azimuth

    Azimuth FKA rtaylor76, Friend

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    So for a surround amp for my cinema JBL 8340A's, I have narrowed it down to two amps because they meet the budget:
    • Crest FA601 - 150W at 8 ohms.
    • Onkyo M-5000 - 105W at 8 ohms (not the M-5000R reference amp)
    Should I even be concerned with coming from an unbalanced source and the input impedance on the Crest is going to be 10K and sensitivity is at +4 (.775V)? I am mostly concerned with the Onkyo with such a low damping factor (40) and the fact I gotta run speaker cables through my attic for the rear surrounds.

    Which is the better choice here or the trade-offs?
     
  6. Azimuth

    Azimuth FKA rtaylor76, Friend

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    Never mind.

    Went with the Crest FA601. Realized the Onkyo consumer amp was not real watts and more of a class H affair with a power pack even to reach the wattage it had, and no level control. The Crest also sets me up if I ever get a balanced surround receiver. I think the Crest is pure class A/B as well.
     
  7. nishan99

    nishan99 Friend

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    I asked this question on the 'All Purpose Advice Thread' but didn't had any luck. I think the question was not clear so I will try to ask it here a bit better.

    So I basically want to understand the current delivery of amplifiers.

    If for example we have amplifier A that has 40 amperes of maximum current and amplifier B which has just 20 amperes.

    Does the amplifier A deliver more current to speaker X that has a load of 4 ohms with a 4 volts signal compared to amplifier B powering the same speakers with the same signal?
    or is the amount of current delivery the same between the two amps and it only depends on the speakers and the input signal?

    That's of course assuming all other variables are the same for both amplifiers.
     
  8. Azimuth

    Azimuth FKA rtaylor76, Friend

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    Given your example of 4V at 4ohms is only 4 watts. The current will be the same. Can only follow ohms law.

    Given that, at 4V at 4Ohm load, that equals 1amp with a power of 1 watt.

    Voltage (V) = Current (I) * Resistance (R)
    Power (P) = Voltage (V) * Current (I)

    Now some amps will have different input sensitivity ratings depending on the amount of gain and the power output of the amp. So you might have two 40W amps, but one has a higher sensitivity (meaning needing less V rms to reach rated power) will output more amps/power given the same source output. Does that make sense?
     
  9. nishan99

    nishan99 Friend

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    It does. Thanks a lot!.

    I asked this question because I see some companies bragging about having ridiculous amount of amperage in their amps like say Hegel and Naim so I was thinking if it's doing something or just an overkill current reserve. It's seems the latter, headroom I guess : ).
     
  10. Azimuth

    Azimuth FKA rtaylor76, Friend

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    Yes. Amps are rated at a certain power and distortion spec (THD). Higher wattage amps will have lower distortion at lower volume levels and higher headroom.
     
  11. Priidik

    Priidik MOT: Estelon

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    Very high instant current delivery (tens of amps) often means just lots of psu capacitance, high psu rails, low impedance path (tons of paralleled output devices and good wiring layout) to a short. In an output shorted schenario, when the amp does not have a short detection or overload prevention, it will unload from the full reserves of the cap banks through rather low res path. Only limitation to the current would be the path impedance. This will be instataneous power surge, not continuous.

    No consumer amp can deliver 40A continuous to 8 ohms (12+ kW?).
    Not even to 4 ohms.
    Not even peak to said loads.
    This figure is for shorted scenario most likely.
    Shorted outputs, the loop impedance would be very low, thus even 100A+ would not be unreasonable to achieve momentarily from 40V rails.

    Marketing wank-talk.
     
  12. kee7a

    kee7a New

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    Hey, I'm playing around with the idea of building a new system (for movies and music) and wanted to see if anyone had any recommendations on speakers / general setup.

    I currently have LS50 Ws on my desk that I really enjoy. I may move the LS50s to the TV area, but am still looking at options and would need to get something new for the desk if I did move the current speakers. Also, I'm less familiar with speakers, but if it helps, I am a big fan of the focal utopia sound.

    I want to try using 2 aegirs if possible, but I'm concerned about the low wattage / synergy with some of the speakers I'm looking at. Currently I've been looking at the SVS ultra tower / bookshelf. If I cant use an aegir, I would probably get a vidar.

    Is it worth trying to use an aegir for the class Aish sound? Are there any other speakers that may work well with that amp? Am I missing something entirely here that I should look into? Thanks!
     
  13. ampguy

    ampguy New

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    So, I've been pondering bi-amping to get my Hood 1969 amp driving tweeters. I ordered a pr of JBL 530s and will have them in early Dec.

    Plan to first use the passive network and drive high end with hood 1969 10-15W Class A amp from the Hegel variable pre outs, the Hood also has a pot. For low end, amp will be a Hegel H90 driving. May play with an active crossover or dsp later.

    Currently using the H90 with either LS-50s or Tekton Mini Lores. Prefer Mini Lores about 80% of the time for my particular room and setup.

    Any suggestions would be welcome. The 530s won't arrive until early Dec. None of my other speakers support biamping.
     
  14. purr1n

    purr1n Desire for betterer is endless.

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    It shouldn't be a problem.
     
  15. Bitter

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    So... I have my Speaker setup working but the entry level amplifier (Tangent APM-100) I got for free is struggling a lot. When I tried to crank up the volume (to "party" level) I had clipping... It's still decent sounding at low listening volume but too bassy.

    The Loudspeaker (Whalfedale Evo 4.2) are 87dB (2.83V 1M) under 8 ohms and minimum impedance is 4 ohms. I have the opportunity to get a used Creek 50A for about 600$. It's a bit more powerful has more current but It isn't night and day in power. It has XLR balanced imput (for Schiit Modius) which is a plus.

    I will upgrade the amp sooner or later but I'm not really the kind of guy that keeps changing gear every year I like to buy stuff and keep It until It dies so should I buy It because It fits my budget Today or maybe wait and buy a more expensive Amp that would fit my needs for longer something maybe twice that price used ?
     
    Last edited: Jan 10, 2021
  16. rlow

    rlow A happy woofer

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    Cant find the Creeks (Creek?) AM50. Any link to it? How far are you sitting from the speakers again?
     
  17. Bitter

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  18. JayC

    JayC Resident Crash Test Dummy

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    I had a creek evolution before my vidar, it was pretty decent (can't remember if it was the evolution 1 or 2). It did well with the harbeth p3esr I had, but I felt like the vidar drove it better. I found the vidar was able to really bring out a better level of bass performance, which was a good thing because of the relatively weak bass of the harbeth. I had a set of dynaudio x12 before that which did quite well with the creek too. Good but not something special. No experience with the 50a but it should be fairly similar.

    Coming to think of it, for 600$ you could easily get a vidar..
     
  19. Bitter

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    Well comparing a Poweramp and an integrated amp isn’t really fair, I would need a preamp with volume control of some sort...

    In Europe there are few used Vidar and price is almost 1000$ If I add a saga I reach 1500$.

    Then maybe that’s a better option to wait and find those used in the long run..
     
  20. JayC

    JayC Resident Crash Test Dummy

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    Yeah you're right, I forgot about the preamp. But it's surprising that a used vidar is $1000 considering that a new one is 770€ or so. I've seen them for much cheaper, also sagas.. Probably need to search for a while?
     

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