Gain Structure
Printed From: Speakerplans.com
Category: General
Forum Name: Newbie Discussion
Forum Description: Newbie Discussion/Questions. Look less stupid here...
URL: https://forum.speakerplans.com/forum_posts.asp?TID=106923
Printed Date: 20 April 2024 at 12:10am
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com
Topic: Gain Structure
Posted By: Aymara
Subject: Gain Structure
Date Posted: 05 March 2022 at 10:26pm
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Hello everyone I bought a QSC MX3000A with 1200w/8ohm stereo and 2 void v18's, each 1000w/8ohm so 2000w/4ohm. When i put my gain on not even 1/3 my amp already starts clipping. A friend said to me i should set up the gain structure correctly but I don't know anything about that. (It's only for my subs and kick in one cabin, the mid section and top section did a friend for me). Can anyone give me a bit more info about how to set up gain structure? And for this amp and driver?
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Replies:
Posted By: Lucasdude
Date Posted: 05 March 2022 at 10:55pm
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Hello, can you list the other equipment you are using, and the type of cabinet the Void drivers are in? Fyi, MX3000a is 800wpc@8ohms. |
Posted By: Conanski
Date Posted: 05 March 2022 at 10:57pm
What equipment is in your signal chain? How is the amp configured? Are you driving 1 speaker per channel or is the amp bridged? How are you powering this amp? 120v or 220v? If you don't have it configured for 220v operation you're wasting your time IMO, because you need the bridged output to fully drive those speakers and you can't get that from a 120v circuit.
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Aymara wrote:Posted By: Aymara
Date Posted: 05 March 2022 at 11:14pm
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Gain on the mixer, i always put the gain on the amp on maximum And i power it with 220v, and i put 2 drivers/channel (not bridged) just for now cause i don't have a limitter yet.
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Posted By: Lucasdude
Date Posted: 06 March 2022 at 1:18am
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That amp is not ideal for subwoofer use, and certainly not in the way that it sounds like you want to use it. However, the more info you provide, the more likely it is that someone may be able to help you. I've read your last post a few times, and I'm more confused than I was after the first one! |
Posted By: Conanski
Date Posted: 06 March 2022 at 2:59am
Ok... so what is the mixer? And is there anything else between the mixer and amp? This amp only needs 1v input for full output according to the specs which means it will reach full output at or below 0dB signal level on many mixers. And the signal is the only thing that matters.. not the control positions, that is what setting gain stages correctly for your equipment is all about.
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Posted By: Esc4pe
Date Posted: 06 March 2022 at 9:50am
Really!? I’ve heard nothing but good stories about MX3000/MPX 1200 in bridge? Definitely wouldn’t be putting 2 v18s on one channel but on bridge I would see that as a fine setup!
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Posted By: Earplug
Date Posted: 06 March 2022 at 10:03am
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"When i put my gain on not even 1/" Do you mean the actual channel Gain - or channel sliders? And what is your setup, ie do you have an LMS or xover? You really need to give more information. A chain is a chain - it has several links, not just a mixer and amp!  ------------- Earplugs Are For Wimps! |
Posted By: Aymara
Date Posted: 06 March 2022 at 10:19am
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Sorry for al the confusion My setup is jb systems talent mixer - behringer dcx2496 - qsc mx3000a - void v18 1000
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Posted By: Aymara
Date Posted: 06 March 2022 at 10:21am
| And LucasDude: I heard that that amp is ideal for sub! Almost everyone i know with pd1850 uses that one |
Posted By: Lucasdude
Date Posted: 06 March 2022 at 10:51am
I would be surprised if an amp with a damping factor of 200 and a manual that only quoted 4 ohm bridged out @1khz and not 20-20 as it does for its other specs is ideal for subwoofer use, but tbh I haven't used one.
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Posted By: Aymara
Date Posted: 06 March 2022 at 11:57am
| So the qsc mx3000a isn't ideal at all for sub? And i heard that you can bridge it at 4ohm, the factory just didn't put it on the sheet. |
Posted By: Lucasdude
Date Posted: 06 March 2022 at 12:04pm
That's not what I said. It's up to you what you do with your kit, but I suspect that amp will not be happy driving the 2000w 4ohm load you have, either bridged or on a single channel. I also asked you which cabinet type the drivers are in, as this will affect the amps performance. If you drive a subwoofer cabinet below its tuned frequency at high power levels, particularly with an amp with a less than stellar damping factor you can expect problems of the expensive kind. What sort of crossover or speaker management do you have?
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Posted By: fat_brstd
Date Posted: 06 March 2022 at 12:11pm
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The MX3000a went on to become the RMX5050a & CMX2000a, both are based on the MX3000a design and all 3 are great amps. Nothing wrong with the MX3000a on bass at all, great tone and decent power for the time is was made. Only issue would be the age of the unit, they will be at least 20 years old now. The easiest way to fix this is to turn the output gain on the DCX2496 on the sub out channel down so that the amp hits clip when you are the limit of the mixer. You will probably need to set it to something like -12dB for it to work. with the rest of your system. ------------- Melbournes Rootical Warrior Roots - Dub - Steppers http://www.facebook.com/adrians.wall" rel="nofollow - facebook page |
Posted By: Aymara
Date Posted: 06 March 2022 at 12:11pm
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They are in paraflex O type cabins, it's something new: https://www.facebook.com/groups/bassaz/posts/5102095523138867 And for crossover, it's in my processor (behringer dcx2496), I would cross on 30Hz - 80Hz or something. |
Posted By: Aymara
Date Posted: 06 March 2022 at 12:13pm
| So on the behringer dcx i need to set -12dB for the sub channel? |
Posted By: fat_brstd
Date Posted: 06 March 2022 at 12:23pm
You will need to experiment to find out what is the correct setting but it will be somewhere around -12dB on the sub channel gain. Without having everything in front of me I cant give you an accurate figure, that is something that you have to work out yourself because it is different with every set up. This is part of the gain structure. The output gains on the crossover should be adjusted so that each section of your system is balanced in sound and that the amps hit maximum power when you have the output from the mixer at maximum. ------------- Melbournes Rootical Warrior Roots - Dub - Steppers http://www.facebook.com/adrians.wall" rel="nofollow - facebook page |
Posted By: Conanski
Date Posted: 06 March 2022 at 4:54pm
Looks like that mixer only has RCA outputs so what are you using to connect to the DCX.. RCA to XLR cables? If so that is fine but it makes the results you are getting even more puzzling because that mixer probably only produces consumer level(-10db) output levels.. I don't know I can't find a spec sheet. That means you should have the opposite problem with not enough drive signal, so the only possibility I see is that you have the gains cranked up in the DCX. So.. what are the current settings inside the DCX? Routing? Summed mono or stereo? Input and output gain levels? Crossover? EQ? Limiting? |
Posted By: Peter Jan
Date Posted: 06 March 2022 at 9:05pm
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Unless you have your mixer in "red" and/or the DCX EQ boosted, levels at
+ several dB and things like that, I think the amp is in for a
checkup/repair. Knowing those amps and certainly the age they have now, it might be one of the the higher voltage rails/amps of the three stages that don't work for whatever reason. In that case you'll have an amp of a few 100 Watts, which is what seems to be the case here... clipping with barely some input. |
Posted By: Aymara
Date Posted: 07 March 2022 at 9:19am
But if i do that, it's very silent...
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Posted By: Aymara
Date Posted: 07 March 2022 at 9:20am
| I don't know how to quote a message so this is a very unclear message haha |
Posted By: DMorison
Date Posted: 07 March 2022 at 10:29am
Use the "Quote" rather than "Reply" option..... |
Posted By: DMorison
Date Posted: 07 March 2022 at 10:33am
| Re: Setting output level on the DCX: Disconnect your speakers from the amp, play Pink Noise as a test signal, put the output of your mixer where you want it, turn down the output of your DCX until the clip lights on the amp stop lighting up. Reconnect speakers, play normal program material, check the balance between mains and subs - adjust main outputs down on DCX to get good balance with the sub level. |
Posted By: Aymara
Date Posted: 07 March 2022 at 10:49am
| Alright i try that when i'm home but what do you mean with "turn down the output of your DCX until the clip lights on the amp stop lighting up"? |
Posted By: DMorison
Date Posted: 07 March 2022 at 11:30am
| You said in the first post the amp was clipping earlier than you expected, this is one (basic) way to set your gain structure to minimise the chance of that happening. |
Posted By: Aymara
Date Posted: 07 March 2022 at 1:08pm
| Yes but how you turn down the output of a DCX? |
Posted By: Earplug
Date Posted: 07 March 2022 at 1:28pm
Use the limiter. Available on each output channel. ------------- Earplugs Are For Wimps! |
Posted By: Aymara
Date Posted: 07 March 2022 at 2:18pm
| I don't get what you're saying... How do you turn down the output? Can you say it in different steps? |
Posted By: DMorison
Date Posted: 07 March 2022 at 2:33pm
Sorry, I haven't used the DCX enough to know this immediately but it will be in the manual, look for it there
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Posted By: Earplug
Date Posted: 07 March 2022 at 3:32pm
The thing has a limiter on each O/P channel. You can use that to make sure that you don't clip your amps. OR:- Yes, read the manual! ------------- Earplugs Are For Wimps! |