Need Stereo Advice

senior chef

senior chef

Senior Member
I recently purchased a stereo amplifier (Technical Pro RX 38 UR) that is rated at 1000 watt peak power.
Unfortunately , it does not produce much volume. Even at max volume it barely produces any audio. Not remotely loud. Shouldn't a 1,000 watt amp/receiver be able to shake the house ?
Does anyone have any idea of what's happening ?
 

Hi, @senior chef. I don't know what a 1000 watt amp/receiver should be able to produce, but if you're not getting much audio at all, I'd say that there's something wrong with the equipment. Can you return it to the place where you bought it?
 
senior chef said:
I just checked my passive speakers. They are 6 ohm, 5-20 watt.
Does that really make a difference ?
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It should not make that much difference. I have seen some speakers that had fuses to protect them. I suppose that if those fuses were blown, some small amount of audio signal could still get delivered to the speakers via other return paths.
 
Pecos said:
It should not make that much difference. I have seen some speakers that had fuses to protect them. I suppose that if those fuses were blown, some small amount of audio signal could still get delivered to the speakers via other return paths.
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I doubt that they could have been blown. When I hooked them up, I had the amp turned off and when I turned it on I very slowly increased the volume.
 
I would be curious to know if you get sound out of the headset jack. Do you have a headset you can try. I you don’t get any sound there, that will provide additional insight.
 
I can't specifically address what your problem is. I wasn't familiar with your equipment and did a quick google and found it on B&H Photo's site. As you said it's claiming 1000w peak output.

In the question section someone wanted to know what the RMS power was-- meaning what can it deliver continually. Here is what the retailer replied:
The manufacturer has not provided this specification. I would estimate that this receiver offers no more than 60-80 watts RMS @ 8 ohms speaker output rating.

If that is an accurate guess( I think that's probably on the optimistic side), The specs stated on your speakers it still should be loud enough for an average listener--which may not be loud enough for what you need. I'm sure you've already checked all your connections and settings. I'm guessing it's a defective unit.

Have you tried hooking your speakers up to surround terminals just to see if it works there?
 
Pecos said:
I would be curious to know if you get sound out of the headset jack. Do you have a headset you can try. I you don’t get any sound there, that will provide additional insight.
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Yes, I do get SOME sound from my head phones. BUT, like the external speakers it is NOT loud.
 
Oris Borloff said:
I can't specifically address what your problem is. I wasn't familiar with your equipment and did a quick google and found it on B&H Photo's site. As you said it's claiming 1000w peak output.

In the question section someone wanted to know what the RMS power was-- meaning what can it deliver continually. Here is what the retailer replied:
The manufacturer has not provided this specification. I would estimate that this receiver offers no more than 60-80 watts RMS @ 8 ohms speaker output rating.

If that is an accurate guess( I think that's probably on the optimistic side), The specs stated on your speakers it still should be loud enough for an average listener--which may not be loud enough for what you need. I'm sure you've already checked all your connections and settings. I'm guessing it's a defective unit.

Have you tried hooking your speakers up to surround terminals just to see if it works there?
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I don't understand what RMS means. (60-80watts ?) That seems very low to me. The unit is supposed to deliver 1,000 watts peak output. How is RMS different from peak output ????

PS: My speakers are 6 ohms , rated at 5-20 watt. Wouldn't an amp that was delivering only 60-80 watts blow the speakers ????

It unit may be ok for the average listener but I want to be able to "rock the house" while working in the kitchen. It may be ok for low volume "elevator music", but i want to listen to old fashioned classic rock.
 
RMS is very similar to average power. Peak power is an instantaneous measurement. LOL, if your amp were putting out a 1000 watts of RMS power you would have to beef up your house wiring.

The fact that your headset level is low is key here . I suspect that your amplifier is not working correctly.

How are your inputs? Does your unit have a built in FM receiver and how is that sound ?
 
Pecos said:
RMS is very similar to average power. Peak power is an instantaneous measurement. LOL, if your amp were putting out a 1000 watts of RMS power you would have to beef up your house wiring.

The fact that your headset level is low is key here . I suspect that your amplifier is not working correctly.

How are your inputs? Does your unit have a built in FM receiver and how is that sound ?
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I have a CD player wired directly to the amp. Poor volume.
Yes, there is a built in FM receiver. Same as the CD player. Poor volume.
Poor volume on the headphones also.
 
Just a thought... it's not a European model designed for 240Volts being run on 110Volts is it?? I think there is a switch on the back.

RMS = Root Mean square. As the voltage output from the amplifier swings positive and negative, if you just measured it directly, it would appear to be zero. So, if you square the measured signal, the value is positive. You take the average of this and then find the square root. This gives you an indication of the true power.

Now, manufacturers will used all sorts of terms to make the amplifier sound more powerful. RMS power is usually calculated using a constant sine wave. Music however is anything but constant so its average is generally higher. Music also has peaks and troughs, so if you state the instantaneous power of a musical peak, it will be much higher again. and as this is stereo, manufacturers will quote the sum of BOTH channels.

The only reliable value is continuous RMS power per channel into a specified resistance. (both channels driven simultaneously)

1000W Peak output will probably equate to about 100W RMS per channel if you're lucky.

OK, maths bit over.. You should match the amp and the speakers. No use having a 100W amp and 20W speakers. It is possibly worse to have a 20W amp and 100W speakers. Quality speakers usually need power to drive them. If the amp can't deliver that power, the output will 'clip' and sound distorted. This may cause the speakers to overheat and get ruined.

If you are going to rock the house, I'd recommend that you get good speakers. They will cost you - maybe $1000+ , but are worth it.

My own system uses a Technics amp rated 100w RMS per channel into 5 ohms driving a pair of Bowers & Wilkins floor standing speakers (25-125W, 5 ohms).
The bass response from these speakers is truly awesome.
I use a Sony direct drive turntable with a Goldring cartridge tracking at 1.5 gms for my vinyl.
 
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You've probably done all this but here's my $00.02
Is there a mute button on the amp and is it turned off?
Is the graphic equalizer or bass/mid/treble controls turned up and not flat-lined?
That's all I got, good luck!
 
Capt Lightning said:
Just a thought... it's not a European model designed for 240Volts being run on 110Volts is it?? I think there is a switch on the back.
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I don't know if it's a European model but I'll find out. I do know that the voltage switch was set to 115 volts when it arrived.
 
I looked up the "specs" on this unit, and finally found a good summary on the Walmart website, This "1000 watts" seems almost irrelevant, but according to Walmart, this thing is supposed to send 150 Watts per channel to the speakers, That would be enough to destroy your eardrums if you were using speakers capable of handling that much power. I have an old Sansui 9090DB that I bought decades ago, and it sends up to 125W/channel, to a set of large JBL speakers. At half volume, it can knock pictures off the wall.

Something doesn't sound right about this unit....At a price of about $90, I suspect that is built more to transfer music to an SD card, etc., rather than supplying sound to a set of good speakers.

https://www.walmart.com/ip/Technical-Pro-RX38UR-Professional-Stereo-Receiver/46689815?athbdg=L1700
 
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Don M. said:
I looked up the "specs" on this unit, and finally found a good summary on the Walmart website, This "1000 watts" seems almost irrelevant, but according to Walmart, this thing is supposed to send 150 Watts per channel to the speakers, That would be enough to destroy your eardrums if you were using speakers capable of handling that much power. I have an old Sansui 9090DB that I bought decades ago, and it sends up to 125W/channel, to a set of large JBL speakers. At half volume, it can knock pictures off the wall.

Something doesn't sound right about this unit....At a price of about $90, I suspect that is built more to transfer music to an SD card, etc., rather than supplying sound to a set of good speakers.

https://www.walmart.com/ip/Technical-Pro-RX38UR-Professional-Stereo-Receiver/46689815?athbdg=L1700
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Yes, no question about it SOMETHING is very wrong. In frustration, I ran a test using cheapo speakers. I turned the volume up to the max and it will not even overload a set of cheap speakers that I used for a test. Those speakers are only 5-20 watt, 6 ohm.
I never heard of a unit that is built to transfer music to an SD card. ????????
 
senior chef said:
Yes, no question about it SOMETHING is very wrong. In frustration, I ran a test using cheapo speakers. I turned the volume up to the max and it will not even overload a set of cheap speakers that I used for a test. Those speakers are only 5-20 watt, 6 ohm.
I never heard of a unit that is built to transfer music to an SD card. ????????
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After reading the info on the Walmart site, I suspect this unit is an "economical" device designed to transfer music to/from a cell phone. I would be Very Skeptical of a Stereo that costs this little...Most Good stereo's cost far more. It's possible that your unit is defective, and you might contact their customer support, or the company you bought it from, to see if they have an answer, or will replace this unit.
 
Don M. said:
After reading the info on the Walmart site, I suspect this unit is an "economical" device designed to transfer music to/from a cell phone. I would be Very Skeptical of a Stereo that costs this little...Most Good stereo's cost far more. It's possible that your unit is defective, and you might contact their customer support, or the company you bought it from, to see if they have an answer, or will replace this unit.
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Yes, Amazon has requested that the seller company contact me. I believe that Amazon will probably give me a refund. However, I doubt that it is as you suggested. There are numerous inputs for this unit.
 

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