Juan Acevedo

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About Juan Acevedo

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  1. How many AMPs to run this XTi Rack

    Consider that in most buildings you will get 208Volts from a three phase system rather than 220V In a home you will get 220V single phase. You could have a long run to the panelboard which will give you some additional voltage loss. On a 30A CB you can only put a load of 24A max. (80%), so you are a little over the limit. You might want to consider a 40A/2P CB with #8 Wire. There are a few more issues, but since I will not be able to fully explain them in simple terms I will refrain.
  2. Realistic idea?

    Thanks, very much. You made my day. Will try it as soon as I can.
  3. Realistic idea?

    I been adjusting my XTi1000 ( for subwoofers) and found: 1. Looks like the Low Pass Filter is only 3db/Oct? The Slope is very shallow and not adjustable. I put it off. 2. I did not try the High Pass. 3. The Equalizer is what they call a paragraphic. The Q is set so you can not make a very narrow filter. 4. I tried the subharmonic Synthesizer, but after some critical listening put it off as it did not sound natural (My very own opinion) In general the Equalization I was able to make improved my low frequencies, but left me with a desire of what could I do if I had a parametric Eq instead of a paragraphic. Questions to Crown: 1. Is there any chance we could a get a parametric in a firmware revision. 2. Could you please give specifications on the DSP Functions. Ex. Filter slopes. etc.. 3. I read the Subharm.. halves freq below 60Hz and adds these +3dB, but then you have that slider to increase it further. A little confusing...
  4. Connecting power amps

    You could download JBL Professional Sound System Design Manual - 1999 Edition (Pt.1) from the JBL WEB SITE - 'Technical Library' for free. There is also a revised Part 2. Study it and you can see that a real answer to your question is a little more involved. In short you would need to know: Indoors or outdoors. What SPL Level do you need at the audience farthest away. You need to know this distance to the loudspeaker. Then you need to know the sensitivity and power rating of your loudspeaker. Then you calculate how much power you need to produce the intended SPL. If your Loudspeaker can take this power, then you know the size of the power amplifier you need. You also need to leave a crest factor of 2 or 3 db. Wire gauge and line losses in the wire must be accounted for. In your case Biamping is not a good alternative. For example if your loudspeaker is Two way horn type: When you take the crossover network out your Hi Freq driver is A High Efficiency unit but has a limited power rating which you could easily exceed and the unit will need protection from low frequencies.
  5. Which Sub Woofer Driver for PS-400

    I have two 18" Maelstrom subwoofers with dual 8 Ohm voice coils. I use the XTI 1000 to drive them. ( Home use ) I had them wired for parallel operation @ 4 Ohms. Then I changed to using just one coil @ 8 ohms to see what difference it would make. Conclusion: I prefer the single 8 Ohm connection. The very Low Frequencies are somewhat a little more loose. If I were to buy new subs today I would find one with a single 4 or 8 Ohm voice coil. I use an Outlaw Bass Management unit to get stereo subs. I cross them at 120 Hz, because that way I maximize the stereo effect.
  6. Power Ratings

    Because Daniel was trying to understand the relationship between power ratings and ohm's law, I will comment again. Going back to the melting of the #12awg wire. A standard cb (20-60A Frame) has an interrupting capacity of 10,000A. In most situations because of the Dry type transformer's impedance this current will not be more than 5,000A. So let's say we have a short circuit of 5000A. The magnetic portion of the cb will trip instantaneously (within a couple of cycles if I remember correctly, industrial cb's can trip in a quarter cycle) 5000A x 120V = 600,000VA that went through the wire. After the short circuit clears you can reset the CB and see that the wire did not melt. It did not melt because there was not sufficient time to heat the wire to its melting point. So it can be seen that power amps wattage ratings don't mean much unless you add time to it. And we can see that ohm's law is good for steady state calculations where time is not part of the equation. (Oversimplification).
  7. Power Ratings

    Opps!!! forgot to do the spell check. I meant thermal I meant instantaneous.
  8. Power Ratings

    It has to do with time versus current. A circuit breaker is a themal/magnetic unit. 1. The magnetic portion of cb will trip basically when you have a short circuit or an instataneous big surge in current. 2. The Themal portion is by a bimetal heated by the load current. So it takes time for the breaker to hit the limit. For example ( From Cutler Hammer's catalog) a 1 pole 15amp cb would trip in not less than 10 seconds and not more than 150 seconds on a 30 amp current. It is this time lag which comes handy for power amp mfr's. That range between 10 and 150 seconds is a very long time in musical terms. Different mfr's use different standards in measuring the power output of their amplifiers. We can not use the basic ohms law to figure it out. However, if it is a trusted manufacturer like Crown you can trust their ratings to be valid. In summary you need to know the standard the manufacturer is using, get a copy of that standard and study it, to really understand what the new math is. Very confusing.
  9. Crown I-Tech power

    It should be noted that Circuit Breakers only protect the wire from melting. It does not protect the load per se. Amplifiers are protected by the fuses inside the amp not by the circuit breaker. #12AWG Wire amp is rated at 20A, usually loaded to 80% max. and protected by a 20A circuit breaker. #10 awg wire is rated at 30A, and protected by a 30A circuit breaker. #6 awg wire is rated at 50A, so unless you are using a #6 awg wire you don't need a 50A circuit breaker.
  10. Crown D-75A

    If the DC300 is being fed by an Electronic Crossover, I would add a passive high pass filter for protection and also an in line fuse. This babe if a remember correctly can pass DC to your loudspeakers. The same goes to the 511B Horn/Driver. Use a (passive filter) capacitor in series to cut at 6db/oct at 400Hz if you are crossing at 800Hz electronically. It's only for protection of the driver and fuse the loudspeaker line.
  11. XTi series amps

    Thanks for posting that picture of your system. It brings memories of my Altec Barcelona speakers. (+- 1980's) I suppose you go down to 500Hz on the 511B. It is great for projecting Pavaroti's voice and for us hobby trumpet players. and you had the guts to use another one for the center channel, wow!!
  12. XTi specs the details please

    In regards to the XTI DSP. You just said 6 band parametric per channel? Good news, I was unenthusiatically expecting a 4 band paragraphic as per specs. Waiting for July 1...