Switchers - How to properly connect multiple amps to one DAC output

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by rhythmdevils, Nov 7, 2020.

  1. Erroneous

    Erroneous Friend

    Friend
    Joined:
    May 15, 2016
    Likes Received:
    1,525
    Trophy Points:
    93
    Location:
    Texas
    Since we're talking about an Amazon purchase, you could just buy the TC and send it back if you don't like it, then try the eBay one. I don't know what the aux jack does in 2in4out config, but if you just never plug anything into it, I would think it'll just stay out of the way.

    I wasn't trying to spend $600+ on an RCA switch, and this was the best solution I found at a price I was willing to pay.
    I haven't been able to discern any audible difference with it in the signal path, so I'm happy.
     
  2. bilboda

    bilboda Florida boomer

    Friend
    Joined:
    Nov 20, 2016
    Likes Received:
    822
    Trophy Points:
    93
    Location:
    Miama
  3. rhythmdevils

    rhythmdevils Best SBAF member of all time

    Friend Staff Member Gearmaster
    Joined:
    Apr 15, 2020
    Likes Received:
    8,261
    Trophy Points:
    113
    Location:
    Bay Area
    I don’t have those kinds of skills unfortunately. Just never got into DIY amp building. Electronics gives me a headache.

    I bought the eBay one and these 1/4” vinyl letters and I’ll mark the inputs/outputs on front and back myself.

    https://www.amazon.com/Chartpak-Self-Adhesive-Capital-Letters-01006/dp/B0006VRX30

    there’s actually a wiring diagram in the description of the item so I can at least figure out what is what without testing. And I think this is probably the best unit.
     
  4. Jer925

    Jer925 Rando

    Joined:
    Oct 24, 2020
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Usa
    Ideally I would want to get something that switches the ground, I dont think there is anything like that so you would have to make their own.
    [​IMG]
    this one is just using the case the pass the ground so I am not sure if the sound quality is going to be very good.
     
  5. rhythmdevils

    rhythmdevils Best SBAF member of all time

    Friend Staff Member Gearmaster
    Joined:
    Apr 15, 2020
    Likes Received:
    8,261
    Trophy Points:
    113
    Location:
    Bay Area
    Aw shit I already bought it. The TEC unit looks better? I thought the absence of a circuit board was an improvement.... I know nothing haha. :bow:
     
  6. rhythmdevils

    rhythmdevils Best SBAF member of all time

    Friend Staff Member Gearmaster
    Joined:
    Apr 15, 2020
    Likes Received:
    8,261
    Trophy Points:
    113
    Location:
    Bay Area
    We need an expert. Paging Dr @dBel84

    which passive RCA switcher looks better or do you have a preference?

    Here’s a Behresford clone

    [​IMG]

    And one I found on ebay

    [​IMG]
     
  7. Jer925

    Jer925 Rando

    Joined:
    Oct 24, 2020
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Usa
    If you don't hear any quality difference with the switcher than it's doing it's job. If you hear on the other outputs faintly it may not be a problem. It's a little bit of leakage but headphone amps are amplifying it.

    On a quality preamp (I know preamps are switching inputs, not outputs, but just an example) it use relays to switch each inputs so to ensure the signal path is only physically connected to one at a time. The absolute best thing is physically connect something when you need it.
     
  8. cameng318

    cameng318 Friend

    Friend
    Joined:
    Jun 14, 2020
    Likes Received:
    217
    Trophy Points:
    33
    Location:
    Wyoming
    I've never used aliexpress, but this one might be close to what you are looking for. It only has one pair in and 3 pairs out, so there's only one switch in the signal path. It uses WBT solder and silver plated OCC wire. (I don't like silver plated wires, but they are in everything. These clear plastic coated wires looks cool to me though) Looks like grounds are not shared (there are both pro and con about it). It's sides are not shielded, which may translate to either noise or open sound depend on your perspective.
    Internal:
    [​IMG]

    I also found the Switchcraft 640 that made me wet my pants. It's totally overkill for this task, but I think it's cool to look at so I post it here:

    a used one on ebay
    for parts on ebay

    front and back panel of the used one:
    [​IMG]
    [​IMG]

    internal of the one for parts:
    [​IMG]
     
    • Like / Agree Like / Agree x 1
    • List
  9. Jer925

    Jer925 Rando

    Joined:
    Oct 24, 2020
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Usa
  10. Jer925

    Jer925 Rando

    Joined:
    Oct 24, 2020
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Usa
    That looks nice, it does say not "Not public ground", and you can also see from the other shots each jack has 2 wires to it.
    it does not say you can use as 1 in, 3 out, but it should work that way.

    Except those silver plated wires may sound harsh on a Drop 789.. granted it's a short distance.
    I found silver plated wires are cheaper than quality copper wires, maybe a buyer can contact them to make one with the best copper wires they have got. I may be dreaming.
     
  11. dBel84

    dBel84 Friend

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    2,722
    Trophy Points:
    93
    Isolating ground can have it's benefits but for most applications it does not matter.

    When I build a purist amp I keep left and right channel grounds separated through the volume pot and they only become part of the circuit ground with the potentiometer connection to the board. How critical is this for sound - most likely nothing and probably not measurable from a channel crosstalk perspective ( in relation to measuring the same amp with common ground vs ground lines separated). In fact, switching the ground with a cheap switch is probably worse than hardwiring all common grounds. The problem that jer925 is referring to likely stems from amps sources treating their ground paths differently ( and some amps/sources not being connected to IEC ground ) and there is then a risk to bleed noise from one noisy source into all the others through the ground path.

    You could argue similar challenges for headphones that share a common ground ( all do through the TRS ) but some people are true believers in only using 4 core wire for headphones.

    Based on the images, it would appear that the Behresford clone keeps the grounds ( common to left and right channel ) separated from the other sources whereas the ebay version creates a common ground for all.

    The Aliexpress version is impressive looking, it uses CNC RCA jacks which if genuine use a teflon insulator with gold plated copper. No idea about the switch but it appears to keep the grounds separate.

    If you end up suspecting that there is noise introduced from the switcher you have - send it to me and we can swap out the switches for high quality 4 pole units which will keep signals and grounds separate.

    The most important thing from a load perspective is to isolate the circuits from one another and any of these units will do that for you.

    ..dB
     
    • Like / Agree Like / Agree x 5
    • List
  12. rhythmdevils

    rhythmdevils Best SBAF member of all time

    Friend Staff Member Gearmaster
    Joined:
    Apr 15, 2020
    Likes Received:
    8,261
    Trophy Points:
    113
    Location:
    Bay Area
    Thanks Don!

    here’s a cheaper version of the Alliexpress unit with a metal chassis but the same components. Lots of great internal closeups in the description page.

    https://a.aliexpress.com/_mNJ1o2D

    [​IMG]
     
  13. dBel84

    dBel84 Friend

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    2,722
    Trophy Points:
    93
    that sure looks like a 3 pole 3 way selector switch which will switch out the ground ( both channels joined at the PCB ) too
     
  14. rhythmdevils

    rhythmdevils Best SBAF member of all time

    Friend Staff Member Gearmaster
    Joined:
    Apr 15, 2020
    Likes Received:
    8,261
    Trophy Points:
    113
    Location:
    Bay Area
    Too bad I need a 2 in 3 out switch. I contacted the company and asked them if they would make a 2-4 unit but that’s wishful thinking.
     
  15. dBel84

    dBel84 Friend

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    2,722
    Trophy Points:
    93
    You need to switch inputs and outputs?
     
  16. dBel84

    dBel84 Friend

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    2,722
    Trophy Points:
    93
    Might be better to modify one of the commercial ones or just make one to spec
     
  17. rhythmdevils

    rhythmdevils Best SBAF member of all time

    Friend Staff Member Gearmaster
    Joined:
    Apr 15, 2020
    Likes Received:
    8,261
    Trophy Points:
    113
    Location:
    Bay Area
    I got the eBay unit and it has some cross channel bleed too though not as bad as the other one. Should have got the Behresford clone!

    I added sticker numbers on the front and back. They’re way too big it looks like one of those phones for old folks with the huge buttons. But it works. I may buy the Behresford unit instead.

    here’s pictures of my number sticker hack job.

    [​IMG]

    [​IMG]
     
  18. dBel84

    dBel84 Friend

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    2,722
    Trophy Points:
    93
    need to teach you how to solder - could have isolated the switched to see if they were to blame
     
  19. rhythmdevils

    rhythmdevils Best SBAF member of all time

    Friend Staff Member Gearmaster
    Joined:
    Apr 15, 2020
    Likes Received:
    8,261
    Trophy Points:
    113
    Location:
    Bay Area
    Yes it’s kind of embarrassing that I have no soldering skills but electronics is really not my forte. I’m afraid I would not get far and it would require a lot of time and energy investment in an audio world where there are now commercial amps for lower prices. I’d still love to build an EHHA though that would be awesome.
     
  20. rhythmdevils

    rhythmdevils Best SBAF member of all time

    Friend Staff Member Gearmaster
    Joined:
    Apr 15, 2020
    Likes Received:
    8,261
    Trophy Points:
    113
    Location:
    Bay Area
    I added this to the top of the first post to hopefully help everyone out and make this easy.

    TL;DR
    It is not safe for DACs to daisy chain amps via “PASS” jacks from one output in the DAC. Read this thread to find out why.

    If you need to hook up more than one amp to a DAC the best/right way to do it is to buy a switcher. I will list the best units below for balanced XLR and se RCA.

    Balanced XLR:

    Nobsound 1 in 3 out

    Nobsound 3 in 1 out


    SE RCA:

    1 in/out 3 in/out

    (it’s passive so you can you can use these either direction)

    these 2 are the best, available on AliExpress in wooden or metal enclosures. The metal is probably better for SQ and cheaper.

    Wooden version

    Metal version


    2 in/out 4 in/out

    Beharesford clone on Amazon
     
    • Like / Agree Like / Agree x 4
    • List

Share This Page