richardash1981 Posted February 15, 2015 Share Posted February 15, 2015 I didn't however hear this bass lift when I ran out of the MP7 mixer into an external amplifier so it seems that this happens within the amp processor section itself shown below.You can see that when I used the MP7 as just a power amplifier the mixer is bypassed at the switched TRS sockets, unless of course there is more filtering that occurs between these sockets and the power amplifier that isn't shown on the block diagram? http://i1191.photobucket.com/albums/z474/warrenstuart/MP7Amp_zps4a791d81.jpg The processor must incorporate limiting and compression I guess because this bass boost I can't achieve with my normal setup incorporating a graphic equaliser as it just drives the speakers too hard without getting the desired effect.I think that bass lift comes from the block marked 'pole-zero compensation', which I'm guessing is tuned to a specific set of speakers the amp is supposed to work with. The lift will be arranged to happen just as the target speakers response rolls off, which effectively gives the system more frequency range at the expense of power handling - presumably why the processor provides limiting! The BOSE 802 boxes do the same thing with their line level processing box before the amps. I'm not surprised that having half the pair (speakers and processing) doesn't sound great - I did a job with 802s and no processor once, which didn't sound nice! The other thing which you have is the low-cut filter, steeper than most EQ bands at 12dB/octave, so the very low stuff is being trimmed out at the front end of the power amp. Does your graphic have a separate sub filter you can kick in? The Behringer parametric EQs I use have 12 db/oct edge filters available (separate the main EQ) for this kind of purpose. Link to comment Share on other sites More sharing options...
sam.spoons Posted February 15, 2015 Share Posted February 15, 2015 The OP actually prefers the sound of the Dynacord power amps with his EV speakers over the sound with his other DSP-free power amps http://www.blue-room.org.uk/public/style_emoticons/default/biggrin.gif It's the usual old thing, if it sounds right then it is right. 802's do sound horrid without the processor (and not all that much better with one IMHO) Link to comment Share on other sites More sharing options...
shuffletech Posted February 17, 2015 Share Posted February 17, 2015 802's do sound horrid without the processor (and not all that much better with one IMHO) We are so spoilt these days. Link to comment Share on other sites More sharing options...
warrenstuart Posted February 19, 2015 Author Share Posted February 19, 2015 I think that bass lift comes from the block marked 'pole-zero compensation', which I'm guessing is tuned to a specific set of speakers the amp is supposed to work with. The lift will be arranged to happen just as the target speakers response rolls off, which effectively gives the system more frequency range at the expense of power handling - presumably why the processor provides limiting! The BOSE 802 boxes do the same thing with their line level processing box before the amps. I'm not surprised that having half the pair (speakers and processing) doesn't sound great - I did a job with 802s and no processor once, which didn't sound nice! The other thing which you have is the low-cut filter, steeper than most EQ bands at 12dB/octave, so the very low stuff is being trimmed out at the front end of the power amp. Does your graphic have a separate sub filter you can kick in? The Behringer parametric EQs I use have 12 db/oct edge filters available (separate the main EQ) for this kind of purpose.Yes my graphic does have a seperate sub filter, I didn't think of switching that in when doing the tests.As soon as I get chance I'm going to run a frequency sweep on the MP7 amp and plot a curve just to see what it looks like, down the bottom end very similar to the one I posted on page 1 I'm guessing! 802's do sound horrid without the processor (and not all that much better with one IMHO)I used to DJ in a bar back in the 1980s that had 4 x 802s installed and just used to take my turntables and mixer in. I got there one night and the Bose processor had failed and been taken away for repair, the bar owner said "but it's ok the engineer said you can just plug in here instead", of course HERE was straight into the amp... god it sounded awful Warren. Link to comment Share on other sites More sharing options...
KevinE Posted February 20, 2015 Share Posted February 20, 2015 Ive got a PM1000 in for repair at the mo, if I get the go-ahead I might run it through smaart if I get 5 minutes to see just where all this happens..for curiosity's sake. The brickwall clip limiter is in the amp section and only comes in if you push the desk really hard, so for the most part it's out of circuit and doesnt colour the sound. Link to comment Share on other sites More sharing options...
warrenstuart Posted February 21, 2015 Author Share Posted February 21, 2015 Ive got a PM1000 in for repair at the mo, if I get the go-ahead I might run it through smaart if I get 5 minutes to see just where all this happens..for curiosity's sake. The brickwall clip limiter is in the amp section and only comes in if you push the desk really hard, so for the most part it's out of circuit and doesnt colour the sound.It would be interesting to see your results if you get a chance to do that. Link to comment Share on other sites More sharing options...
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