Hi everyone. Got a question I recently purchased two macrotech 5002vz they work great and everything but one of them seems to play more loud that the other, it even clips earlier than the other. Any clue what may be the problem here.
I noticed that one seem to be made earlier than the other not sure though, I also noticed the one that plays louder uses crown oem output transistor, and the other uses crown and onsemi transistor. So if anyone have any idea please let me know.. TIA
I noticed that one seem to be made earlier than the other not sure though, I also noticed the one that plays louder uses crown oem output transistor, and the other uses crown and onsemi transistor. So if anyone have any idea please let me know.. TIA
Maybe different input sensitivity set by internal switch (GAIN)? Try to find that switch and check if it is set equally .
Measure the total supply voltage across collector to collector for each channel’s output stage. I’ll bet one channel is 2X the other. It is normally supposed to run on the high voltage, but switch to low when it’s on board analog computer tells it that the junction temps are running too high to operate at full voltage. One channel may be stuck in that low state. That control circuit is complicated, and fixing it is not recommended for a beginner. Even a run of the mill fix it shop could miss this and send it out the door partially working. Other things can cause this too, but it’s the first place I‘d go looking. You may luck out and find something “easier” to fix.
Crown just has the outputs binned by hFE and vbe, and gives them unique numbers so trained monkeys at the factory can effectively match them. Regardless of which production run they come from. If you just follow normal matching procedures yourself with regular off the shelf ON parts you’ll be fine.
Crown just has the outputs binned by hFE and vbe, and gives them unique numbers so trained monkeys at the factory can effectively match them. Regardless of which production run they come from. If you just follow normal matching procedures yourself with regular off the shelf ON parts you’ll be fine.
@wg_ski, did you ever see how vz function, I think that higher voltage power supply is only active when there is request for it. So, when amp is on lower output, below some level defined by analog board, it will be on low power supply level, but when it reaches level which is higher then lower power supply level can fulfill, amp requests from vz part to switch to aprox. double voltage of the lower power supply. ODEP is designed to protect the amp from destroying itself.
Because of that my previous post refers to level switch.
If the problem is when high output power is demanded, maybe vz part is not working correctly.
Power supply on that amp is single, but when you measure it with reference to audio gnd, you'll have it split. It is important to check voltages, because some reference voltage divider tend to fail.
If there is knowledge to check internals by schematic, I have it.
Because of that my previous post refers to level switch.
If the problem is when high output power is demanded, maybe vz part is not working correctly.
Power supply on that amp is single, but when you measure it with reference to audio gnd, you'll have it split. It is important to check voltages, because some reference voltage divider tend to fail.
If there is knowledge to check internals by schematic, I have it.
The VZ circuit actually works the other way around, running at high voltage until it “can’t”. It switches down to half voltage when the transistor junction temp runs too high. Running sustained at 2 ohms and high volume it does this pretty much all the time, resulting in a stiff lower rail that doesn’t drop under load. They get the same power at low Z that would have been developed by the higher supply rail drooping, and lower transistor junction temp. Hence, the “VZ” concept. I’ve read the Crown white papers on this - their designers pretty much rejected the idea of the voltage changing on the fly on a cycle by cycle basis like most class H amps (like QSC and all its clones) do.
Upon checking the manual crown says the amplifier will operate at low voltage mode on startup and when output power demand is low, this they said is done to prevent temperature rise. When more power is needed then voltage will raise to compensate as stated in the manual
@k20 That is correct and good, so I will advise you to check is VZ switching to about 160-180V when it is demanded. Check electrolytics, are the same, they should be of same characteristics (same internal resistance and same capacitance, I mean about capacitors on VZ board or part of the board, I was repairing 3600VZ which had VZ part on separate board).
Capacitors should be the same, because when VZ is in series that components are crucial, think of about two batteries connected in series (as VZ description explains).
Capacitors should be the same, because when VZ is in series that components are crucial, think of about two batteries connected in series (as VZ description explains).
Ok so i did do some deep checks, both set of the capacitor read almost identical. I did test a few stuff on vz board everything adds up correct.
Nevertheless i swap out the preamp board to narrow down possible problems and guess what the problem had transferred to the other amp I checked everything to see if they are good if any loose solder or bad IC sockets nothing seems bad. What i did notice is that the sensitivity switch seems to be stuck. Only working in 23db mood, on both channels. I had these switched to 0.775v first. Nevertheless after switching both the amp to 23db the input eventually correspond with each other.
I guess i can work with them in 23db for the time being. But will this affect sound performance? Because crown claims that 0.775v is the highest gain setting.
Nevertheless i swap out the preamp board to narrow down possible problems and guess what the problem had transferred to the other amp I checked everything to see if they are good if any loose solder or bad IC sockets nothing seems bad. What i did notice is that the sensitivity switch seems to be stuck. Only working in 23db mood, on both channels. I had these switched to 0.775v first. Nevertheless after switching both the amp to 23db the input eventually correspond with each other.
I guess i can work with them in 23db for the time being. But will this affect sound performance? Because crown claims that 0.775v is the highest gain setting.
I think that there is no influence on sound quality, it (switch) defines how much gain you will have.
Try to desolder the switch and disassemble it, clean it and assemble it on the board. This option will restore full functionality of the amp.
With 23dB you will need to put more voltage from the preamp (or mixer) to reach the full power on the output of the amplifier.
Regards
Try to desolder the switch and disassemble it, clean it and assemble it on the board. This option will restore full functionality of the amp.
With 23dB you will need to put more voltage from the preamp (or mixer) to reach the full power on the output of the amplifier.
Regards
Running the amps at a lower gain is better noise-wise, especially in their intended use. Noisy environments, long cables. They run the line levels pretty hot, but all the associated equipment is designed with that in mind.
In some sort of semi-pro or home use whatever preamp box you use ahead of it may or may not be better than the op amps used in the Crown. They are sufficient for the task, but not any “better”. You could make much better - premium instrumentation op amps and discrete output stages that can do 60Vp-p driving a balanced line. And you can buy a LOT worse (which is what people often do, with 4558 op amps and +/-9V unregulated supplies).
If you end up getting early clipping in low gain mode you might take a look at your driving source. It may not be up to the task (as in the 2nd example).
In some sort of semi-pro or home use whatever preamp box you use ahead of it may or may not be better than the op amps used in the Crown. They are sufficient for the task, but not any “better”. You could make much better - premium instrumentation op amps and discrete output stages that can do 60Vp-p driving a balanced line. And you can buy a LOT worse (which is what people often do, with 4558 op amps and +/-9V unregulated supplies).
If you end up getting early clipping in low gain mode you might take a look at your driving source. It may not be up to the task (as in the 2nd example).
What volt do you recommend running these 5002 in? I currently have them set to 120volt. Also another question do you guys know
If parallel speakers increase the combines speaker wattage?? I know the that amplifier wattage will increase as load increased, but as for the speaker does the wattage increase?
If parallel speakers increase the combines speaker wattage?? I know the that amplifier wattage will increase as load increased, but as for the speaker does the wattage increase?
Parallel speakers = decreased load impedance = increased amplifier load. It’s like plugging two lights into a socket instead of one.
If there is a way to strap a given amplifier for 240V input instead of 120V, it usually results in better real world performance. The only problem is the need for a dedicated outlet. With as much as these can draw you need a dedicated 120V socket anyway (don’t plug anything else with heavy load in with it). But 240 isn’t available everywhere and you need to keep that in mind for your application.
If there is a way to strap a given amplifier for 240V input instead of 120V, it usually results in better real world performance. The only problem is the need for a dedicated outlet. With as much as these can draw you need a dedicated 120V socket anyway (don’t plug anything else with heavy load in with it). But 240 isn’t available everywhere and you need to keep that in mind for your application.
Ok so after checking the switches and cleaning them out….. nothing it still behaves the same, also i notice when switching to 0.775 the gain become lower than 1.4v. Not sure if this is a chip fault or what, there are no signs of corrosion or broken traces on this one, but the other ones is in a bit rough shape, (corrosion wise) I know these amplifier boards are susceptible to salty air so I would have expected troubles from the other one, I had both of them clean and treated, with anti corrosion spray. This should help them last for atleast a 100years. Anyways I decided I will use them in 1.4v.
@wg_ski ok understood
I have a custom built step up step down transformer with double 10 guage copper wire, this I am using with them all the time, to step up 108-120volts for them right now (sometimes 115,110, etc).
Right now both amplifier are driving 8 18”, 4 speaker to one amp 2 per channal, and the currant draw peaks to 35-40 amps on both amplifier combined.
So my thoughts are that I should run them on 240 coil.
I have a custom built step up step down transformer with double 10 guage copper wire, this I am using with them all the time, to step up 108-120volts for them right now (sometimes 115,110, etc).
Right now both amplifier are driving 8 18”, 4 speaker to one amp 2 per channal, and the currant draw peaks to 35-40 amps on both amplifier combined.
So my thoughts are that I should run them on 240 coil.