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Thread: Quiet Solid State Amplifier Recommendations

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    Quiet Solid State Amplifier Recommendations

    Anyone have any favorite amps large and small for running high efficiency speakers including compression drivers with respect to background noise (hiss/hum) in a multiway active crossover system? My old Biamp,QSC,Phase Linear, and Crown PS-400 all seem too loud unless the gains are turned way down. Thanks.

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    If you can build anything yourself, I would suggest some of the gainclone amps. They can be very quiet and clean. You could easily make a multi-channel amp with them without spending much money. There is almost nothing to them. At least for the mids and tweets.

    Bruce

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    Trekman ,

    This is always an issue.

    Not only your amps but also preamp and active crossover will contribute to noise.

    Why swamp your system with noise and distortion?

    Unless you are running a PA and want to squeeze every last drop of power one solution is to pad back the horns to a sensible sensitivity like say 97-100 dba.

    Why you ask?

    The benefit is in picking up 10 db on your S/N ratio and you also get improvements from pushing the signal chain 10 db harder.

    This is important when you are sitting 15 feet from the mouth of those horns!

    You amps will also sound cleaner running above of the sub 1 watt range where they tend to be most non linear....Another reason why horns sound subjectively better with passive crossovers to some audiophile purists!

    Ian

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    RIP 2014 Ken Pachkowsky's Avatar
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    Quote Originally Posted by trekman
    Anyone have any favorite amps large and small for running high efficiency speakers including compression drivers with respect to background noise (hiss/hum) in a multiway active crossover system? My old Biamp,QSC,Phase Linear, and Crown PS-400 all seem too loud unless the gains are turned way down. Thanks.
    This is a can of worms that I had opened and dealt with for almost a year before completely solving it. Have all your equipment using the same electical circuit. DO not use cheater plugs to solve the problem.



    My Westlake’s use an active 4 way crossover with balanced in's and out's. "The best piece of advice I ever got relating to hum problems was from Bo". He suggested dropping pin 1 at every input on evry piece of electronics. Some techs call this telescoping balanced interconnects.



    Being that my monitors require 3-4 guys to move I dabbled with changing some cables to the above and eliminated most of the problem. It's when I hired 4 guys to move the monitors and painted the living room that I got the opportunity to reconnect everything. I built all new cables using Canare Star Quad cable and Neutrik Gold XLR's with all pin 1's dropped per Bo's instructions. Dead silence was the end result, even running up to 8 separate amps. You literally have to put your ear up to the mouth of the large horns to hear even a slight hiss. The hum in the 2235's is non existent. I also built new RCA connectors using the same cable.

    The point is, hum is not normal if your equipment is wired properly and in good working order. I waisted a ton of time and money buying isolation transformers and screwing around when the answer had been given to me 8 months before. I wish I had painted sooner

    Ken

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    Quote Originally Posted by Ken Pachkowsky
    This is a can of worms that I had opened and dealt with for almost a year before completely solving it. Have all your equipment using the same electical circuit. DO not use cheater plugs to solve the problem......He suggested dropping pin 1 at every input on evry piece of electronics. Some techs call this telescoping balanced interconnects..............
    Ken
    My equipment chain is this: Preamp to a KT DN410 EQ (which has the balanced box checked off on it) with a RCA to XLR adaptor cable, to a XR4001 crossover with XLR-XLR cable. (I don't know if the KT has been modified for polarity, I plugged it in and it worked) Then some amps xlr and some rca or 1/4 phono. My cables are all under 10 feet, so I assume balanced operation won't save much noise. I did notice removing ground from those pro amps that had 3 pin power plugs reduced noise about 1/2. Home amps seem to have 2 pin power plugs. Do balanced inputs really make any difference with short cable runs?

    Pin 1 is the ground pin. So break the ground path between units? This can't be done with the RCA or 1/4" non TRS cables, right? Can the chassis or something else be grounded between units, even though the theory seems to be eliminating grounds?

    One really can't use the 2 pin AC adaptor? Doesn't drop noise totally either. I checked amps with a shorted or open input and they seem quite quiet on their own. Thanks.

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    Bo is Dab hand at this stuff, zip him a pm.

    Incidentially you should never lift or remove the amp ground from the mains, it tends to reduce life expectancy statistically!

    Ian

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    Senior Señor boputnam's Avatar
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    Quote Originally Posted by trekman
    So break the ground path between units? This can't be done with the RCA or 1/4" non TRS cables, right? Can the chassis or something else be grounded between units, even though the theory seems to be eliminating grounds?
    trekman...

    Sorry - missed this.

    You haven't mentioned your problem/symptom, except that the described signal path and interconnects is fraught with opportunity for ground loops...

    But, the first trouble-shooting step is actually upstream from where you started.

    1) Disconnect all device inputs to the pre-amp, but leave the pre-amp connected to the EQ, etc.
    - No noise? Then, your problem lies between the preamp and the devices (a "common" location).
    - Noise? Then, your problem lies from your preamp onward.

    Come back with a report, and we'll work on that decision tree.

    Oh, and please do not use an AC plug adaptor to lift the AC ground. Really a bad idea. You might have lessened the symptom (hum), but have not fixed the problem and have now voided gods warranty on you...
    bo

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    Hello
    I would look over the gain structure of your system, adding a lot of gain at one point only to turn it down at another or adding a lot of gain to make up for a low level some where else.
    I know the Phase Linear and the Crown will have unbalanced inputs, most likely RCA on the Phase and 1/4 tip sleeve on the Crown. The PSA 400 is basicly a DC 300 dressed up a little for home use. Depending ont he age and model of the QSC and Biamp they could be either way. The Older QSC MX series of amps had 1/4 inch balanced inputs that are wired with the tip (-) and the ring (+) backwards from most 1/4 tip ring sleeve balanced inputs. You mentioned using RCA to XLR adaptors. Short of using a active or transformer unit to do a balanced/unbalanced conversion you can adapt an unbalanced output to a balanced input or a balanced output to a unbalanced input you need to tie pin 3 (-) to pin 1 (ground). In the case of you Klark Teknik EQ that most likely is wired with pin 3 (+) you would tie Pin 2 to Pin 1, however if you would use pin 2 input to output you would not hear the difference. The adaptor you have should be able to be opened up to check the wiring by removing the XLR pins by turning the screw that on that end in to allow the pin body to slide out. Unless your adaptor had the RCA connector insulated from the rest of the XLR connector body it will connect the signal ground to the chassie ground on the XLR equipment that you plug it in to. Most pro audio equipment has the chassie ground isolated from the audio signal ground and or has a switch or a jumper to remove to help in ground hum isolation. Pin 1 lifting between equipment is a effective way to reduce or eliminate hum. An easy thing to do is make up a few short cables or buy adaptors with pin 1 dissconnected and try connecting them in at different places to see where you need them before cutting the connections on you perminate cables, just unplug one end and add your pin 1 life cable to the line. Also having everything powered from the same power source can help.

    Mike Caldwell

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    While it is a receiver, my Yamaha RX-Z9 is dead quiet through my very efficient 130A/LE175/075 system. If their high end amps are as good...

    For the Yamaha, you have to put your ear right up to the speakers to hear any residual noise. On the other hand, my dBx subwoofer amp through a 130A is easily heard in my quiet room in the seating position 13 feet away. Ambient levels in the room are on the order of 30 dBC.

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    Thanks for all the helpful responses. I have eliminated sources before the preamp as noise source. When preamp is directly hooked to 1/4" non TRS Phase A60 amp, the noise is the least. Also inserting AC adaptor makes no difference. I suspect, because the Ashley crossover has TRS ins and outs, and the Phase doesn't, I need to make up a cable from XLR to 1/4, what would the pin connections be to the tip and sleeve? Is this the correct way or can it still be done using non trs 1/4" cable? Also, some mention lifting pin one, while others mention connecting pin three to pin one. Later I will tackle the Klark, right now that is out of the loop.

    Thanks, Malcolm

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    Senior Señor boputnam's Avatar
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    Hey, Malcom...

    Still need to know, with only preamp and Phase amp you still get a GL?

    And, the preamp has balanced outs? If so, I worry about the balanced -> RCA adaptor, but you can try making one. Drop Pin1, and only connect the signal (+) and (-). But, I expect this will howl. Maybe not. Never can be sure.

    If so, or otherwise, get an isolation transformer between the two components. We covered this in another thread recently. There's a number of ways to go. Let me search for that thread for you. HERE: http://audioheritage.csdco.com/vbulletin/showthread.php?p=75586#post75586

    If the preamp has balanced outs, and so does the KT, these interconnects are likely not the source of the GL.

    I think the problem arises from that Phase amp. Since it is the last thing in the signal path, once it is connected it could be causing a host of problems upstream that otherwise appear/sound good.
    bo

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    Quote Originally Posted by boputnam
    ...

    Still need to know, with only preamp and Phase amp you still get a GL?

    I think the problem arises from that Phase amp. Since it is the last thing in the signal path, once it is connected it could be causing a host of problems upstream that otherwise appear/sound good.

    The preamp (DB-1A) is standard RCA affair, and the Phase runs very quite when directly connected. I don't think the Phase causes upstream damage. I noticed my Biamp 2400 makes all the other amps hum, thats why I went to the Phase. I would prefer not to get any transformer couplers, and try the wiring route first.

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    Senior Señor boputnam's Avatar
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    OK, well, in the meantime, maybe some clarity would come from you doing the following:

    1) How did you determine there is not GL coming from devices plugged into the preamp? The preamp having only RCA outs (not what I first understood...) makes me wonder about it.

    More importantly:
    2) Please list all the component names, models and bal or unbal.

    It's confusing without more detail...
    bo

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  14. #14
    Senior Señor boputnam's Avatar
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    Quote Originally Posted by trekman
    When preamp is directly hooked to 1/4" non TRS Phase A60 amp, the noise is the least.
    OK, this is making more sense.

    You are going:

    DB-1A preamp -> (RCA-1/4 unbalanced interconnect) -> Phase amp

    Correct? And that has "the least" noise? But, it is not noise free?

    So, we need to work from the speakers, backwards:
    1) Phase amp -> Speakers, only. No Noise? Go to #2
    2) DB-1A preamp -> Phase amp -> Speakers. No noise? Go to #3
    3) post your findings. Then the riddle continues...
    bo

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    Quote Originally Posted by boputnam
    DB-1A preamp -> (RCA-1/4 unbalanced interconnect) -> Phase amp
    Correct this is the hookup.

    Phase amp only - no hum. very very low noise.

    Add the preamp directly connected to Phase -- tiny bit more noise, but only noise increase comes from turning the volume way up on the preamp, not by merely connecting it.

    Add the Ashly xr4001 xover, in between, more noise right away, just from hooking it up.

    Quote Originally Posted by boputnam
    1) Phase amp -> Speakers, only. No Noise? Go to #2
    2) DB-1A preamp -> Phase amp -> Speakers. No noise? Go to #3
    3) post your findings. Then the riddle continues...
    1) No noise.
    2) No noise.

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