Pro speakers at home

[Sean McKinnon]

The other issue with "digital" type amplifiers is the output can only go 0 to 100. There is no 101+ peak power available like analog amplifiers are able to do. And many, but not all digital amplifiers don't do harmonics very well.

Well... What the Q-Sys amps CAN do is to both bridge and Parallel Channels using FAST (TM) (C) or FLEXIBLE AMPLIFIER SUMMING TECHNOLOGY. I believe they can also send unused power from one channel to another for example if you are driving a 3 way speaker the unused HF power can be applied to the LF section dynamically but don't quote me on that part of it.

[Steve Guttag]

The other issue with "digital" type amplifiers is the output can only go 0 to 100. There is no 101+ peak power available like analog amplifiers are able to do. And many, but not all digital amplifiers don't do harmonics very well.

CX-Q amplifiers have quite a bit more headroom than typical linear amplifiers. They run with 150V rails. When transients and bursts of audio come through, they deal with it better than linear amps.

Here is an oldie but goodie video by Barry Ferrell on DCA versus DPA-Q (same as CX-Q).

https://www.youtube.com/watch?v=4uK8A0pk9bU

[Mark Gulbrandsen]

I'll read it and get back to you, But going past the brick wall of max power out seems pretty impossible.

[Josh Jones]

Older class D amps had issues with transient response related to the PWM reconstructing filters used in the power stage. The filters were necessarily steep to meet the EMI requirements of governments, and this coupled with the relatively low switching frequencies, meant that the filters would ring on transients. Higher switching frequencies and simpler filters resolved almost all of these issues. Noise can still be an issue if the design stage is not executed properly, but modern class d amps are pretty good, especially from reputable manufacturers. All my bench amps are class D, as well as the surround amp in my screening room. Its pretty hard to beat 4 channels in 1RU.

I appreciate the video link Steve! Good video, lots of good practical info.

Josh

[Jon Kros]

By the way just FYI the CXD4.5Q amplifier you mentioned wouldnt help you as the "Q" denotes a Q-Sys amplifier and you would need a Q-Sys core to use it (or atleast to configure it but I still would'nt do it)

Hi, I know but I was told with a core it can be put into stand alone mode. I have someone with access to a core to do this.
thx

[Jon Kros]

I wouldn't really call them Pro Speaker as much as I'd call them Cinema Speakers, since they are job specific. Pro speakers are more to do with sound reinforcement systems and such. Different quantities of different pieces of pro speakers can be put together based on a jobs requirements, where Cinema Speakers systems are designed according to room size.

Hi, sorry I’m not a pro at this…

[Sean McKinnon]

It can but again I wouldn’t because all it will take is a power glitch or something to potentially lose the configuration and then you’re stuck until you can get someone back with a core to redo it.

[Jon Kros]

Hi, I was wondering about the passive crossover. The VHF driver has a built in crossover. But the specs online don’t say at what frequency/slope it’s crossed. I was thinking i can build a 3- way crossover and leave the VHF as is. Anyone know this info?

Thx

[Mark Gulbrandsen]

Older class D amps had issues with transient response related to the PWM reconstructing filters used in the power stage. The filters were necessarily steep to meet the EMI requirements of governments, and this coupled with the relatively low switching frequencies, meant that the filters would ring on transients. Higher switching frequencies and simpler filters resolved almost all of these issues. Noise can still be an issue if the design stage is not executed properly, but modern class d amps are pretty good, especially from reputable manufacturers. All my bench amps are class D, as well as the surround amp in my screening room. Its pretty hard to beat 4 channels in 1RU.

I appreciate the video link Steve! Good video, lots of good practical info.

Josh

Spot on Josh! I've been involved with Class D stuff on and off since the Infinity Class D amplifier of the Mid 70's, and that is the main issue that amplifier had. The QSC thing sounds like an old design of a company that went bankrupt, but whose design was picked up by a semiconductor manufacturer. They originally offered two models before they went bankrupt. Their failure mode was very similar to what Steve said the QSC did. I have to research a bit later today for the name and the patent.

[Josh Jones]

AM transmitter manufacturers went through the same growing pains with class D during the 70's and 80's. Their solution was to increase the number of PWM phases, thus raising the effective ripple frequency by the number of phases. This relaxed the filtering requirements, and allowed simpler filters that didn't ring, and therefore tighter modulation control.

Thanks for the note about QSC stock Steve! Hopefully 3 SC-412C's will be enroute soon.

Josh

[Mark Gulbrandsen]

AM transmitter manufacturers went through the same growing pains with class D during the 70's and 80's. Their solution was to increase the number of PWM phases, thus raising the effective ripple frequency by the number of phases. This relaxed the filtering requirements, and allowed simpler filters that didn't ring, and therefore tighter modulation control.

Thanks for the note about QSC stock Steve! Hopefully 3 SC-412C's will be enroute soon.

Josh

Josh, this is the one I was thinking of. Many major Audio manufacturers use Class T technology including Audio Research who still builds very high end tube amplifiers. There is a lot more on it out on the net.

https://en.wikipedia.org/wiki/Class-T_amplifier

https://connexelectronic.com/wp-cont...A3020v3.10.pdf

[Jon Kros]

Just getting back to this project. I was thinking of using a QSC DPM-300 but not with DCM amps. Those have the proprietary DB15(VGA) data connections. I know I won’t get all the benefits of the presets etc but I have plenty of power amps with XLR or RCA inputs. I can get VGA connector boxes (see pics) and make my own cable adaptors according to the pin out. But this is where I’m a bit confused. Would anyone know how to go about ?

the pin out is in the DCP-30D manual. (See pics)


I can also make an XLR to DB25 analog cable to feed the DPM-300 from my Marantz AVR8802.

anyone who would know this please let me know.
thx