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johnnydrama

Monoprice Tube Amp HELP!

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Hey Guys so I bought this Monoprice tube amp off of Amazon: 

 

https://www.amazon.com/gp/product/B016YS9CSW/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

 

When I power the amp on the Left Channel Speaker just buzzes, very loudly, despite the volume knob being turned all the way down. I've double and triple checked all of my wire connections. Is there any other checks, tubes seated properly, etc ? Or is the Amp more than likely defective?

 

I was really excited to give this a shot in my office at work.

IMG_3224.JPG

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21 minutes ago, johnnydrama said:

Hey Guys so I bought this Monoprice tube amp off of Amazon: 

 

https://www.amazon.com/gp/product/B016YS9CSW/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

 

When I power the amp on the Left Channel Speaker just buzzes, very loudly, despite the volume knob being turned all the way down. I've double and triple checked all of my wire connections. Is there any other checks, tubes seated properly, etc ? Or is the Amp more than likely defective?

 

I was really excited to give this a shot in my office at work.

IMG_3224.JPG

Chinese.

Return it.

Get another.

Most of the time you get good ones.

I have been running and purchasing for friends China amps for 20+ years.

They have it down pretty dam good, however anyone can have a bad batch of components.

Line Power noise is off the charts in an industrial setting.

Floresent lighting in an office could be a cause, take it home and try it?

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Have you tried swapping tubes side to side and see if the problem changes channels?

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So I disconnected the left channel and started playing music via Bluetooth through the right channel only. After a few minutes i connected the left channel speaker wire and it appears to be playing fine now and does not buzz if I stop playing the music. 

 

Definitely a different sound than I am used to. Not sure how much of it is due to the tubes or the Bluetooth connection from my computer. I don't know how to describe it other than it almost sounds Mono as opposed to Stereo?

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Another thought:

To communicate between your devices, Bluetooth sends signals over a 2.4GHz radio frequency. This becomes problematic when other nearby devices are also using that frequency. Wi-Fi is perhaps the biggest and most problematic example, as are other Bluetooth receivers and devices, which can interfere with one another.

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That has to be the case because is the most underwhelming thing I have ever heard. I'm going to connect a device via RCA and give it a shot however I bought the device for the convenience of Bluetooth so not sure I will keep it.

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I'd say to not expect too much from a $129 amp.  It certainly looks good and that is really cheap for an amp with a bluetooth receiver!   Try the CD input and see if that sounds better.  I don't know your experience but I'd argue you really haven't experienced tubes yet if this is all you have tried.   You could always take advantage of the 30 day monoprice money back guarantee.

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Bluetooth can and will spoil everyone, only problem with it and ANY wireless Tech is they ALL transmit and receive.

The Receive is where any device can get "Spurious" random Freq's "Static".

Cell phones, (Everyone has one in there pocket) they are way more power than WiFi/Bluetooth even though their Freq's are different

the power factor of these device's transmitting, can cause static.

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1 minute ago, muel said:

I'd say to not expect too much from a $129 amp.  It certainly looks good and that is really cheap for an amp with a bluetooth receiver!   Try the CD input and see if that sounds better.  I don't know your experience but I'd argue you really haven't experienced tubes yet if this is all you have tried.   You could always take advantage of the 30 day monoprice money back guarantee.

While I agree $129 is cheap for a tube amp, I love my Dayton Audio desktop DTA-1 which is ~$30 and it sounds great in near field listening at a computer. Therefore I expected much more out of this amp. I believe the poor sound is more due to the Bluetooth connection however. I'm anxious to try via RCA.

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5 hours ago, johnnydrama said:

I'm anxious to try via RCA.

You might be thinking of a way to keep it after that.

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I haven't tried RCA yet but connected via Bluetooth from my phone instead of my computer and it sounds much better now. Surprised there would be that drastic of a difference.

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23 hours ago, johnnydrama said:

While I agree $129 is cheap for a tube amp, I love my Dayton Audio desktop DTA-1 which is ~$30 and it sounds great in near field listening at a computer. Therefore I expected much more out of this amp. I believe the poor sound is more due to the Bluetooth connection however. I'm anxious to try via RCA.

I think the little DTA amp is great for listening at your computer.  I carry mine with me to test speakers.

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Tried one of these awhile back, one channel in the amp blew the instant I turned it on.  Sent it back the next day, not a fan of the build quality at all.

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It is what it is... I guess.  I don't know what we expect for such little money.  At least for it to work a little anyway :)

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If you want a cheaper alternative, good value, good build quality and good SQ and performace from a Chinese amp, stick with some of the top players, Yaqin, Music Angle and Meixing.  These are not cheap amps and have high quality party, based on proven amp design.  They can easily equal amps costing 2-3 times the price tag on the US market.  They are beautiful in their design and can be easily worked on for repairs since they are based off Dyanco and other popular amp topology found in the US.

 

I quit trying to make old amps new with re-builds, updates and repairs a few years ago.  Not that some of the amp are not worth it, the cost is quite high and you basically still have no guarantee.

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I would REALLY like to have a tube integrated for my cabin system, KG2s.  But I at least want it reliable. 

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hey, I had the same problem, with ennormouse buzzin,  you need to open the lid on the bottom side of your amp, try to fix connections maybe some cables or plugs  are not connecting, move your tubes as well maybe some pin is connected well, and finally you could try to remove one screw which might be connected to tinned path on PCB withradiator( could be a connection with ground this way sick!!!). I went  these steps with mine and started working, anyway some small buzz is there but much much lower than previously however this one could come from chinese lamps. Anyway Im going to replace chinese with some correct ones.

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On 5/11/2017 at 8:00 AM, johnnydrama said:

Hey Guys so I bought this Monoprice tube amp off of Amazon: 

 

https://www.amazon.com/gp/product/B016YS9CSW/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

 

When I power the amp on the Left Channel Speaker just buzzes, very loudly, despite the volume knob being turned all the way down. I've double and triple checked all of my wire connections. Is there any other checks, tubes seated properly, etc ? Or is the Amp more than likely defective?

 

I was really excited to give this a shot in my office at work.

IMG_3224.JPG

 

I din't read all of the above, buy the first step IMHO is to swap the tubes, one at a time, but eventually all four, left to right and right to left.  Does the buzzing go to the other channel ??  If so, there is likely no amp problem at all, but rather, just a tube problem.  If this is the case, with only two tubes per channel, it will be easy for you to locate the bad tube, and then, replace it.  Wait at least 5 to 10 minutes after shutting down amp, for the tubes to cool, before handling / switching them,  and use a towel  or a rag when pulling them.   Relax and hang in there, and be cool headed.

 

Jeffrey Medwin

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44 minutes ago, Jeffrey D. Medwin said:

I din't read all of the above, buy the first step IMHO is to swap the tubes, (respectful snip!)

 

Had you read any of the above you might have noticed the thread is from 2017. 

 

Doesn't really matter, as your advice is timeless.  😎

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5 hours ago, wvu80 said:

 

Had you read any of the above you might have noticed the thread is from 2017. 

 

Doesn't really matter, as your advice is timeless.  😎

 

 

I'm sorry.  It was early Sunday morning, and my reading time was very limited.

 

I had volunteered to help a young girl, confined to a wheelchair, by picking her up and driving her to church services with me.  Time  to post was short.  Its shades of the January 1. 1956 Columbia LP / OL 5090, from the Broadway play " My Fair Lady ".  The song that comes to mind is .............................." Get Me to the Church on Time ".

 

Jeff Medwin

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