Common ground amps

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Comments

  • SchurkeySchurkey Posts: 1,660
    edited May 8
    analogluvr wrote: »
    What would happen if you didn't use the jumper wire?
    I had no damage, but the sound quality was affected.

    The midrange in my case was exceedingly poor. I would describe it as "phasey" but really I have no ability to describe the characteristic having 20 ohms between the channels imparts. It's bad, but it still sounds like "music". You can tell what song is supposedly playing.

    Another guy on this forum with the same amplifier but 3.1TL speakers said his amp would shut down from the protection circuitry. Mine never did. Maybe I don't play as loudly as he did, maybe my 1Bs weren't as sensitive to this as his...I can't otherwise explain the difference.

    Note that my 1Bs are in most regards the electrical equivalent to your SRS 2 blade/blade speakers. Same active drivers, same crossover except for one resistor in the treble circuit.

    If there were 50 ohms between the channels--or 200--things could be very different.

    I don't even want to guess about using a bridged/balanced amp where both the + and the - are driven.
  • SchurkeySchurkey Posts: 1,660
    pitdogg2 wrote: »
    Now you could use non common ground BUT you would need to NEVER use the SDA cable...
    True, that would allow non-common-ground amplifiers to be used.
    pitdogg2 wrote: »
    ...which negates all the special sound you enjoy from those speakers.
    Not entirely true. The SDA speakers tend to be good speakers that also have the SDA potential. Removing the SDA cable leaves you with...good speakers.

  • analogluvranalogluvr Posts: 72
    So 3BSST is out? It is a dual mono design. Does that always precluded it from having a common ground? If it is dual mono does that mean you cannot strap the negatives?
  • FTGVFTGV Posts: 3,484
    edited May 10
    analogluvr wrote: »
    So 3BSST is out? It is a dual mono design. Does that always precluded it from having a common ground? If it is dual mono does that mean you cannot strap the negatives?
    The 3SST is common ground already connected internally.

    Its the configuration of the amplifiers output stage that determines if it can have its negative terminals strapped together.Amplifiers that have bridged/ balanced output stages cannot be strapped because their negative terminals are not at ground potenial,they are active like the positive side,just opposite in phase. By connecting the negative terminals together you would be creating a direct short between two "live" outputs.This ofcourse could cause damage to the amp depending upon how forgiving it is of having its outputs shorted.

    Amplifiers, be they dual mono or otherwise that have their negative terminals at ground potential can have their negative terminals strapped together without risking damage. Many of these type have small value resistors that isolate the grounds of each channel from the other and safety ground.(So not quite common ground).Strapping the negative binding posts bypasses the resistors making the amp common ground.There will still be a connection to chassis safety ground.
  • analogluvranalogluvr Posts: 72
    OK I'll post this as a follow up for others in case they are reading this. I called bryston today and they said all of their stereo amps are common ground unless you get into the really big models that are essentially four channels in one box that are bridged down to two channels. They said do or mono just means that it doesn't share one power supply it has two, but they can still be common ground. So I think I'm looking for a Bryston 4 BST or newer as some people complain bryston is too bright. My complaint with the speakers is they are a bit smooth so I'm hoping with my tube preamp that a bryston will be a good mix.
    Now when I say my complaint with the speakers I need to qualify that with the statement that I do love them! I love the sound staging! I currently have a set of Tannoy 15's in Homebuilt boxes, A set of all tech 604 E and a set of all tech voice of the theatres. In the past I have had apogee divas, reference three a grand Veenas Vander Steen 2c. I'm listing those so when people read that I love the speakers they have context. That was a worry for me when I was reading up on them to buy them.
  • analogluvranalogluvr Posts: 72
    Thanks for that ftgv, I didn't notice when I left my post.
  • FTGVFTGV Posts: 3,484
    Your welcome.
  • kevinkokevinko Posts: 126
    I want to check an amp to verify that it is common ground. Is the following correct?

    Unplug the amp and disconnect the speakers. Set the multimeter to continuity and select the lowest range available. Take one lead and touch the right negative terminal. Take the other lead and touch the left negative terminal. If it reads zero or close to zero you have continuity and it is a common ground amp.
  • pitdogg2pitdogg2 Posts: 6,583
    Believe that is correct. Then again you could tell us we may already know.
  • kevinkokevinko Posts: 126
    No fun in that. The fun is in the learning.
  • F1nutF1nut Posts: 37,329
    It would be much better to check the resistance.
  • kevinkokevinko Posts: 126
    Gotcha. Thanks.
  • pitdogg2pitdogg2 Posts: 6,583
    edited May 22
    F1nut wrote: »
    It would be much better to check the resistance.

    Good catch i evidently read what i wanted to not what was wrote
  • kevinkokevinko Posts: 126
    And evidently I wrote what I didn't mean to and not what I meant.
  • kevinkokevinko Posts: 126
    "00.6"
  • SchurkeySchurkey Posts: 1,660
    0.6 ohms is a "good" measurement--you'll be fine.
    0.6K ohms is not sufficient.
    0.6M ohms is not sufficient.

    So it all depends on what scale your meter was set to.
  • kevinkokevinko Posts: 126
    200 (no k) was the lowest available.
    So I'm good.
  • BillJGWBillJGW Posts: 7
    Didn't know where to put this, here in an old thread or start a new one. But we'll see how it goes.

    I just want to know if a Denon POA 2800 amp is a common ground amp as I have blade/blade SRS 2's. Thanks.
  • pitdogg2pitdogg2 Posts: 6,583
    BillJGW wrote: »
    Didn't know where to put this, here in an old thread or start a new one. But we'll see how it goes.

    I just want to know if a Denon POA 2800 amp is a common ground amp as I have blade/blade SRS 2's. Thanks.

    Well read above all you need to know is right here. Were it says continuity replace that with resistance. Follow the thread
  • FTGVFTGV Posts: 3,484
    BillJGW wrote: »

    I just want to know if a Denon POA 2800 amp is a common ground amp... Thanks.
    According to the schematic it is.

  • BillJGWBillJGW Posts: 7
    Thanks FTGV. Just wanted to know before I plunked down the money for one.
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