I have a QSC HPR 153F with a dead amp. The output transistors in the LF section are burnt up and shorted.
I posted in solid state for some advice on repair, but I'm starting to get a little worried that I may be in over my head on this, and I really want to end up with a working speaker.
Does anyone have any suggestions on how I could go about putting a replacement amp together from non QSC parts?
Their spec sheet lists:
400 W LF Class H (The schematic calls it a Class B)
100 W MF Class AB+B
100 W HF Class AB+B
The filter types and cutoff's are all listed in the schematic. There are also some eq cut/boost sections I'm sure I could calculate the values of.
Would it be possible to match my other speaker? Is building one amplifier even an option? Are my options only to build 2 new amps or repair the old one?
I posted in solid state for some advice on repair, but I'm starting to get a little worried that I may be in over my head on this, and I really want to end up with a working speaker.
Does anyone have any suggestions on how I could go about putting a replacement amp together from non QSC parts?
Their spec sheet lists:
400 W LF Class H (The schematic calls it a Class B)
100 W MF Class AB+B
100 W HF Class AB+B
The filter types and cutoff's are all listed in the schematic. There are also some eq cut/boost sections I'm sure I could calculate the values of.
Would it be possible to match my other speaker? Is building one amplifier even an option? Are my options only to build 2 new amps or repair the old one?
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There are several ways you could get back to a functional speaker.
The best option by far would be to get your module repaired or replace it with another new or used QSC module.
You could also substitute a new generic amp module.. preferably one with DSP, with that you should be able to get good results but the cost could be significant and there may be challenges with fitting the module as it likely won't be the same dimensions.
You could fit a blank panel with a speakon connector and power and process it with external amps, that is quick and effective but it's clumsy to use.
You could build a passive crossover for it and power it with a single external amp, that is less clumsy to use but a 3-way passive crossover is not easy to do well.
A combination of a 2-way plate amp with a passive crossover between the mid and high driver could also work.
Generic plate amps are getting more plentiful all the time, Parts Express has some now and Ebay does too, I still don't see too many with 3 amp channels though.
I have also seen a series from a direct from China distributor that includes some 3-ch models with DSP.. and at very attractive prices too, but I have no hands on experience with them.
The best option by far would be to get your module repaired or replace it with another new or used QSC module.
You could also substitute a new generic amp module.. preferably one with DSP, with that you should be able to get good results but the cost could be significant and there may be challenges with fitting the module as it likely won't be the same dimensions.
You could fit a blank panel with a speakon connector and power and process it with external amps, that is quick and effective but it's clumsy to use.
You could build a passive crossover for it and power it with a single external amp, that is less clumsy to use but a 3-way passive crossover is not easy to do well.
A combination of a 2-way plate amp with a passive crossover between the mid and high driver could also work.
Generic plate amps are getting more plentiful all the time, Parts Express has some now and Ebay does too, I still don't see too many with 3 amp channels though.
I have also seen a series from a direct from China distributor that includes some 3-ch models with DSP.. and at very attractive prices too, but I have no hands on experience with them.
I looked up the compression driver and the mid driver. They both say 8 ohm impedance.
The compression driver, Celestion CDX1-1425, says it's rated for 25-watts.
The QSC RMX amps look like they were classified with 2 ohm loads, so I'm guessing the wattage ratings on the spec sheet are at 2 ohm impedance.
Does this mean I could use something like, Dayton Audio DSPB-250 2x50W, to run the HF and MF channels?
Or maybe this Dayton Audio PPA800DSP for the low and mid, and this Dayton Audio DSPB-100 100W for the high? Can these products be combined? Will the higher wattage amplifiers cause any issues with these drivers? I assume it's just gain and limiter settings in the DSP.
The compression driver, Celestion CDX1-1425, says it's rated for 25-watts.
The QSC RMX amps look like they were classified with 2 ohm loads, so I'm guessing the wattage ratings on the spec sheet are at 2 ohm impedance.
Does this mean I could use something like, Dayton Audio DSPB-250 2x50W, to run the HF and MF channels?
Or maybe this Dayton Audio PPA800DSP for the low and mid, and this Dayton Audio DSPB-100 100W for the high? Can these products be combined? Will the higher wattage amplifiers cause any issues with these drivers? I assume it's just gain and limiter settings in the DSP.
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That is an RMS rating and for best SQ there should be at least double that on hand for peaks. QSC had 100w available here.
The PPA800DSP 2-way plate amp would be what I'd use with a passive crossover between the 6" and CD, I have heard those mini class D amps really don't generate the claimed output and you will need more power than you think there. Those two amp modules would have to run in parallel and the DSP setup separately, that could work but will be clumsy to install and tune. With a passive crossover between mid and high the relative levels between drivers would be set with an L-pad(resistor network), but all EQ can be done with the DSP in the plate amp. This active/passive combo scheme was common in powered speakers in the early days, it doesn't offer the level of control one gets with a full 3-ch active setup but it can still sound and perform really well.
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Nice find on the AliExpress! Thank you!
Unfortunately, Instrumental Parts doesn't actually have that part in stock. I already checked with them.
The Hypex FusionAmp FA503 (500W+500W+100W) also seems like a possible candidate, though very expensive. They describe the top 100W as a tweeter channel. Would it still work with the compression driver?
Unfortunately, Instrumental Parts doesn't actually have that part in stock. I already checked with them.
The Hypex FusionAmp FA503 (500W+500W+100W) also seems like a possible candidate, though very expensive. They describe the top 100W as a tweeter channel. Would it still work with the compression driver?
The drivers in the 153 are all 8ohm aren't they? If so that makes the Hypex amp a bit underpowered and they only mention crossover presets, makes it sound like there is a limited selection that may or may not match your requirements, you will need to look into that further.
Might be a bit underpowered that way, but you’re not going to burn it out like the original. It probably ran as hard at 8 ohms as most rack mount amps do at 2.
These speakers stay in my living room, for DJ and synth/drum machine practice. I'm open to rack amp suggestions.
Every time I look at that stuff I get the impression that I'm gonna need over 8U and start to get a little uncomfortable, but I was considering getting some type of processor at some point in the future, so a rack in the room was kind of in the plan.
Every time I look at that stuff I get the impression that I'm gonna need over 8U and start to get a little uncomfortable, but I was considering getting some type of processor at some point in the future, so a rack in the room was kind of in the plan.
Repair the one you have. QSC are built like tanks using standard parts available from hundreds of distributors. At my last job, we had dozens of QSC amps, none were ever a problem to service.
+2 on that(I already suggested it once🙂) It's probably not something the OP can do himself and would require a trip to a qualified tech but it would be worth doing even if it costs a couple hundred bucks. These speakers are old now but they hold their value and will continue to do so because of the companies reputation of building high quality products.