I just bought a GX5 to test for home use, but the noice from the fan is really bugging me.
So, I looked around and found some are replacing the original fan with this one: Invalid Request
When I opened up the GX5 to look at the fan and how to remove it, I did not quite see how. The fan has no screws, it looks like it is slided into four plastic pins, and then kept in place by three locks in the plastic bracket. Picture of the inside here:
Test: QSC Endstufe GX5 - Seite 2 von 4 - AMAZONA.de
How to remove the fan?
Do I have to take out the whole plastic bracket, in case how?
Or do I have to open the plastic locks in the bracket and forcefully slide the fan out?
Rovers
So, I looked around and found some are replacing the original fan with this one: Invalid Request
When I opened up the GX5 to look at the fan and how to remove it, I did not quite see how. The fan has no screws, it looks like it is slided into four plastic pins, and then kept in place by three locks in the plastic bracket. Picture of the inside here:
Test: QSC Endstufe GX5 - Seite 2 von 4 - AMAZONA.de
How to remove the fan?
Do I have to take out the whole plastic bracket, in case how?
Or do I have to open the plastic locks in the bracket and forcefully slide the fan out?
Rovers
I think Enzo must be on vacation, you are stuck with me. Nobody but Enzo really experienced watches PA systems often.
Your purchase link didn't come up and I don't think you can buy any fan easily that is as long lasting as the one installed in your QSC, which is a premium brand product. What you need is a fan control circuit that only allows the fan to run fast if you are really playing loud. See the drawing below. The Peavey PV-1.3k has the fan circuit on the left, which allows the fan to run slowly when cold, and goes to full speed, 120 VAC, when the heat sink is hot. Unfortunately I don't know where to buy a thermostat like that except Peavey, they were common as dirt in the nineties but are going away. Microwave ovens used to have them. Newark, Mouser, Digikey, don't as far as I can tell. If you are going to buy from Peavey, just buy the whole fan control board if it will fit in your amp, it is about 3"x3" and has spade lugs for the 120 vac and neutral in and out. I use machine screws with elastic stop nuts (to not fall off) and 1/4" air tubing as standoffs when I mount stuff like this. The Peavey circuit is for a 120 VAC fan. It won't work if your fan is a DC driven fan.
If you can't buy a snap action thermostat, look at the circuit on the right for a 120 VAC fan. You put the 15k NTC thermistor on the heat sink, and it decreases resistance as it heats up. At some point the gate of the FET increases to the trip point and it switches on, putting ~50 ma to the gate of the triac. This runs the fan full blast. The fan resistor is picked from the peavey value, may be different for your fan. I'd buy a number of 47 ohm 10 w resistors (or 5 w) and stack them up for R3 until I got the cold fan speed I wanted. Similarly with R4, if I didn't have a junk box full of resistors I'd buy various 1/2 w 1000 ohm resistors and stack them up until I got the turn on temperature I wanted. You can test the temperature with a temp probe and a hair dryer on the naked NTC resistor.
If your fan is DC, blow off the triac and run the DC straight through the T1 to the fan, using it to bypass the fan dropping resistor R3. Similarly the power supply can be simplified, sucking power from the fan drive circuit instead of the AC line. Having a regulated ~8v DC source for the FET gate is important, you want that voltage to be stable. But you don't need a 5W 1n5344 regulator for just the fet without the triac, as the triac needs 50 ma to turn on. The fet will turn on with microamps, and any tiny wattage zener would do. Increase R2 the zener regulator resistor appropriately for a smaller wattage zener. Or any voltage regulator, you want 6 to 9 volts on the FET gate circuit to swing the fet gate from <1.5 v cold to >4 v hot.
I build stuff like this on NEMA LE laminate, 1/8" or 1/16", that I drill holes in. You can also buy expensive ($10) perf board from electronic supply houses and buy official standoffs instead of cutting them out of tubing. However, use elastic stop nuts, not regular one, as you don't want hardware to come loose and rattle around in an appliance with 120 VAC in it.
Read the safety sticky thread on tube amp forum about working around high voltage if working the AC circuit. Use a clip lead on the meter negative connected to neutral to measure power on, and use one hand at a time, 120 VAC electricity running across your heart can stop it. Make sure the big blade is really neutral, ie at ground potential, a lot of houses, wall and workbench sockets are wired upside down. No jewelry on hands or neck, 2 vdc can burn a finger to charcoal through a ring. Don't work alone. Don't work distracted by a phone or another person. Etc, read the thread.
Have fun.
Your purchase link didn't come up and I don't think you can buy any fan easily that is as long lasting as the one installed in your QSC, which is a premium brand product. What you need is a fan control circuit that only allows the fan to run fast if you are really playing loud. See the drawing below. The Peavey PV-1.3k has the fan circuit on the left, which allows the fan to run slowly when cold, and goes to full speed, 120 VAC, when the heat sink is hot. Unfortunately I don't know where to buy a thermostat like that except Peavey, they were common as dirt in the nineties but are going away. Microwave ovens used to have them. Newark, Mouser, Digikey, don't as far as I can tell. If you are going to buy from Peavey, just buy the whole fan control board if it will fit in your amp, it is about 3"x3" and has spade lugs for the 120 vac and neutral in and out. I use machine screws with elastic stop nuts (to not fall off) and 1/4" air tubing as standoffs when I mount stuff like this. The Peavey circuit is for a 120 VAC fan. It won't work if your fan is a DC driven fan.
If you can't buy a snap action thermostat, look at the circuit on the right for a 120 VAC fan. You put the 15k NTC thermistor on the heat sink, and it decreases resistance as it heats up. At some point the gate of the FET increases to the trip point and it switches on, putting ~50 ma to the gate of the triac. This runs the fan full blast. The fan resistor is picked from the peavey value, may be different for your fan. I'd buy a number of 47 ohm 10 w resistors (or 5 w) and stack them up for R3 until I got the cold fan speed I wanted. Similarly with R4, if I didn't have a junk box full of resistors I'd buy various 1/2 w 1000 ohm resistors and stack them up until I got the turn on temperature I wanted. You can test the temperature with a temp probe and a hair dryer on the naked NTC resistor.
If your fan is DC, blow off the triac and run the DC straight through the T1 to the fan, using it to bypass the fan dropping resistor R3. Similarly the power supply can be simplified, sucking power from the fan drive circuit instead of the AC line. Having a regulated ~8v DC source for the FET gate is important, you want that voltage to be stable. But you don't need a 5W 1n5344 regulator for just the fet without the triac, as the triac needs 50 ma to turn on. The fet will turn on with microamps, and any tiny wattage zener would do. Increase R2 the zener regulator resistor appropriately for a smaller wattage zener. Or any voltage regulator, you want 6 to 9 volts on the FET gate circuit to swing the fet gate from <1.5 v cold to >4 v hot.
I build stuff like this on NEMA LE laminate, 1/8" or 1/16", that I drill holes in. You can also buy expensive ($10) perf board from electronic supply houses and buy official standoffs instead of cutting them out of tubing. However, use elastic stop nuts, not regular one, as you don't want hardware to come loose and rattle around in an appliance with 120 VAC in it.
Read the safety sticky thread on tube amp forum about working around high voltage if working the AC circuit. Use a clip lead on the meter negative connected to neutral to measure power on, and use one hand at a time, 120 VAC electricity running across your heart can stop it. Make sure the big blade is really neutral, ie at ground potential, a lot of houses, wall and workbench sockets are wired upside down. No jewelry on hands or neck, 2 vdc can burn a finger to charcoal through a ring. Don't work alone. Don't work distracted by a phone or another person. Etc, read the thread.
Have fun.
Attachments
Last edited:
Thanks for the reply 
The GX5 uses a 24V DC fan and runs at full speed all the time.
The fan is a SUPERRED 8025 CHA8024EBN-K(E)
24V, 0,24A 80x80x25mm.
I do not know the CFM or noise but it is loud.
I have a fan lined up to replace it, just not quite sure how to remove the original.
I also bought a voltage regulator, but the space is very limited in the GX5 chassis, so going for the replacement fix first.
Any other hints/tips would be greatly appreciated.
http://www.aliexpress.com/item-img/...-24A-Converter-Fan-Cooling-Fan/653424933.html
The GX5 uses a 24V DC fan and runs at full speed all the time.
The fan is a SUPERRED 8025 CHA8024EBN-K(E)
24V, 0,24A 80x80x25mm.
I do not know the CFM or noise but it is loud.
I have a fan lined up to replace it, just not quite sure how to remove the original.
I also bought a voltage regulator, but the space is very limited in the GX5 chassis, so going for the replacement fix first.
Any other hints/tips would be greatly appreciated.
http://www.aliexpress.com/item-img/...-24A-Converter-Fan-Cooling-Fan/653424933.html
if it's a used amp and the fan is going full out i'd start by opening it up and checking it for dust contamination.
these amps do have a temp sense control over fan speed; the sensor is mounted on underside of the heat sink on the bad air flow side of the board. i'm not privy to any mod's or reported failures.keep in mind that these amps where intended for commercial applications and usually live in racks.(or separate rooms)
in your application you could consider putting it in something stylish(rack style) that still allows good ventilation but stops the fan noise from propogating into your listening area.
if your certain the fan and control circuit is bad the schematics are readily available and i think if i can't help many more that frequent here can!
these amps do have a temp sense control over fan speed; the sensor is mounted on underside of the heat sink on the bad air flow side of the board. i'm not privy to any mod's or reported failures.keep in mind that these amps where intended for commercial applications and usually live in racks.(or separate rooms)
in your application you could consider putting it in something stylish(rack style) that still allows good ventilation but stops the fan noise from propogating into your listening area.
if your certain the fan and control circuit is bad the schematics are readily available and i think if i can't help many more that frequent here can!
Sorry for the late follow up.
No, the amp is brand new.
I have seen a lot of PA-amps that have been modded for home use with a fan that is practically quiet compared to the stock fan. The only problem is how to remove the stock one, as the attachment looks a bit tricky.
Separate room is not an option.
Rovers
No, the amp is brand new.
I have seen a lot of PA-amps that have been modded for home use with a fan that is practically quiet compared to the stock fan. The only problem is how to remove the stock one, as the attachment looks a bit tricky.
Separate room is not an option.
Rovers
Temperature-controlled fans are reasonably common in PCs (used for case, CPU, and power supply fans). Search ebay for pc fan temperature control and you'll find various things. Or google it plus diy. Perhaps you can salvage something from a junk PC or power supply; sometimes the temperature control is a separate board.
The Peavey amps that I own have two-speed fans that are virtually silent under normal conditions (as in not a hot day in summer, not playing as loud as possible). If you want to see how they did that, a service manual with schematics is available:
PEAVEY PV8.5C Service Manual free download, schematics, eeprom, repair info for electronics
The Peavey amps that I own have two-speed fans that are virtually silent under normal conditions (as in not a hot day in summer, not playing as loud as possible). If you want to see how they did that, a service manual with schematics is available:
PEAVEY PV8.5C Service Manual free download, schematics, eeprom, repair info for electronics
If you look at this link: http://www.amazona.de/wp-content/uploads/2010/07/8_08-Innenleben.jpg you are able to see the fan.
Do you mean to take out the black pins in the corners of the fan?
Yes I did.
I ordered a fan in ebay, not dead silent, but a lot more quiet than the original Superred that QSC uses.
The only way to remove the fan was to use some force as the fan is quite stuck on the four pins it is slid onto.I testet the two fans in free air, and it was an enormous difference. After confirming it worked, I simply removed the strips holding the cable for the original and took it out(it is still complete in case I need it later). Then i installed the new fan and taped the cables together.
Result, very pleased. Almost can not hear the sound and at the levels I have been playing, the air coming out is still ice cold. I have not pushed the amp, but then, not often you need to do that at home in a small room
Just Discovered Same Situation w/ a GX5
How did your fan work out? What make & model is it and who was the vendor?
Thank you for the advice
That would explain why I had no luck when I tried the first time.
Will give it a go as soon as my new fan arrives in the mail.
How did your fan work out? What make & model is it and who was the vendor?
Thanks for input. My speakers are a pair of EV ZLX-12’s and a pair of ZX1’s. Considering selling the GX5's and using an amp w/o fans in bridged mode for each speaker. I asked EV what their amp power recommendations were but tech support did not answer my question. Probably too much info in my request. I will try again. QSC in their response did not mention they have a quieter amp w temperature controlled variable speed fan. Came across that info poking around. I am baffled by business' lack of responsiveness.
Recommendation
FWIW - I recommend Yamaha's pro-amps. Most of them have adequate heat-sinking, with on-demand fans that are OFF by default but turn on when needed. This makes them excellent for home use, and I imagine still fine for pro use otherwise their warranty department would be busy. Using a P2500S for subwoofer duty at home for exactly that reason.
Best,
Tal
FWIW - I recommend Yamaha's pro-amps. Most of them have adequate heat-sinking, with on-demand fans that are OFF by default but turn on when needed. This makes them excellent for home use, and I imagine still fine for pro use otherwise their warranty department would be busy. Using a P2500S for subwoofer duty at home for exactly that reason.
Best,
Tal
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.