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Review and Measurements of Monoprice Hybrid Tube Amp

JohnYang1997

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It has all become clear. Amir has used the wrong cables with machine. No wonder it has measured poorly. A work of art like this deserves 5 nines annealed silver interconnects.
This is a sarcasm right?
 

restorer-john

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I'm struggling to figure out what the purpose of the tubes is in that amp. Why not just use the Hypex?

Because two UcD-400s, a bridge rectifier and 4 caps is a bit hard to justify asking USD$3995 for- you need some tubes (all two of them) to get those audiophiles to open up their wallets.

Gotta love the effort put into the heatsinking. Not one to do a 1hr precondition, followed by some full power testing. Not sure Hypex would honor the warranties on implementations like that...
1557560830342.jpeg


Rogue Audio. How apt.
 
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JohnYang1997

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Because two UcD-400s, a bridge rectifier and 4 caps is a bit hard to justify asking USD$3995 for- you need some tubes (all two of them) to get those audiophiles to open up their wallets.

View attachment 26030
how much are ucd400s? What peripherals does it need? Is it better than with composite lm3886?
 

solderdude

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How can he be joking when I repeatedly have heard quite obvious differences between the exact same cable ?
It MUST have been the cable as so many buyers, sellers and proud owners of these amplifiers simply can't be wrong !
 

audio_tony

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The Monoprice amp is sold under several different brand names on Ebay UK and vary in price from around £115 upwards.

The only difference I can see, is that none of these have a Bluetooth antenna input near the RCA jacks.
And one has dual VU meters (looks like some form of LCD display or something)

tube amplifier intimidation v1 2/50w bluethooth
https://www.ebay.co.uk/itm/tube-amplifier-intimidation-v1-2-50w-bluethooth/283475743632

Madison MAD-TA10BT tube amplifier 2 x 25 W RMS Bluetooth USB line
https://www.ebay.co.uk/itm/Madison-...-2-x-25-W-RMS-Bluetooth-USB-line/202663909761

Nobsound MS-10D PRO HiFi Tube Integrated Amplifier with Bluetooth Headphone USB
https://www.ebay.co.uk/itm/Nobsound...ier-with-Bluetooth-Headphone-USB/253924889543

Bluetooth 4.0 HiFi Vacuum Tube Amplifier Stereo Class AB High-power Audio Amp
https://www.ebay.co.uk/itm/Bluetoot...eo-Class-AB-High-power-Audio-Amp/272889739043

Nobsound MS-30D hifi tube bluetooth Support Usb music amplifier
https://www.ebay.co.uk/itm/Nobsound...ooth-Support-Usb-music-amplifier/272851809118
 

Xulonn

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The Monoprice amp is sold under several different brand names

Douk Audio, Monoprice, and Nobsound seem to be part of a weird web of marketing entities that rebrand and sell a jumble of audio electronics that are sold around the world under many brand names. They are are not audio design and manufacturing companies. They even rebrand products such as the relatively new Muzishare high quality Chinese amplifiers. They offer a range of quality in their products from horrible (like the amp tested for this thread) to excellent, but make no attempt to identify the quality level of individual products of product lines.

Old pun-luving Monty Python fans like me might say "It's a jumble out there..."

I would tend to want to deal with resellers who sell using the manufacturer's brand names - and I am toying with the idea of buying a tube amp from HiFi Exquis, a Hong Kong reseller with a web presence that at least inspires a bit of confidence.

A few of the Chinese amplifier brands that seem to have earned some respect in the global audiophile market include Line Magnetic (who supposedly also manufacture Muzishare), Meixing Ming Da, Cayin (Spark Electronics), Yaqin, Xindak, Jungson, Opera Audio, Dussun, Sheng Ya and Shanling. LINK
 

HiFiQUEST

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Hello,

I am a bit late to the party but I have an HTA-25B Taga Harmony Amp and the insides do not look like the ones posted here claimed to be by made / designed by Monoprice. Also, the one I got has a BT module and also has USB Playback (FLAC as well). I am no expert but it sounds pretty good to me! Also the price for it in Europe is 299.00.
 

GGroch

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YouTube is a great resource and has several videos showing how to eliminate the hum on this Monoprice Amp.

This poster promises the issue is solved by replacing the tubes. As an old tube radio hobbyist I concur that bad or mismatched tubes can hum, but its odd this would be the case on a new amp.

This poster solved the problem by removing the toroidal transformer from the chassis and placing it 2 feet away. It seems to work but low spouse and small pet acceptance factor.

The next solution makes a lot of sense. Modifying/replacing the caps...that is how I got hum out of most old radios. But wait, in this case he means the caps covering the speaker wires.

On YouTube, everyone can be an expert!

HiFiQuest... you're right, there do seem to be several amps using this chassis that have different internals.
 
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rmo

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This amp is a dog with major fleas. I think the human hear though has a certain like for a little distortion. Maybe not this much though.LMAO :rolleyes:
 

LuckyLuke575

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Thanks for the entertaining comments @amirm, you had my laughing at various points here :D

As this wonderful disaster of an amp illustrates, I'm so tired of cheap and nasty China made audio equipment that takes the money of earnest audio enthusiasts, only to leave them ripped off and disappointed. I'm also value minded, that's why I decided to buy a clean, decent spec'd, mid-range, used Sony integrated amplifier 'MADE IN JAPAN'. The weight, quality, sound and features of the device make it money well spent (just EUR 80).

I recommend to anyone looking for value for money in power / integrated / AV amplifiers to take a serious look at the used market. Especially if you have reputable second hand dealers in your area. People often sell off / give away 'old' hifi systems without knowing what they have. The best is to see the equipment working. Even better is to get buy from a place that offers some sort of warranty. But if you find a killer piece of equipment at a yard sale or charity shop for next to nothing, just throw the dice; your odds of getting a great deal are high. Even if something goes wrong, you have a lot of headroom in terms of cost before get anywhere near breaking even on equivalent new models.
 

NiagaraPete

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I’m embarrassed to admit I own one of these which I’m listening to right now. We call the system the iPatio. Monoprice amp thingy, Paradigm Micro v3, iPhone via Bluetooth and Joe Bonamassa live at Red Rocks. Depending on how much beer and weed (legal in Canada) is consumed it sounds really bad or horrid but better than any of the single Bluetooth speakers. Admittedly I haven’t listened to the Linn. At 6k here I won’t either.
 

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Capitol C

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Every time I see one of these amps at Monoprice I've been tempted, like Ulysses was tempted by the Sirens. Good to be warned that the Sirens sing off key!
 
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tomtoo

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How could i miss this review???

Man 2 years to late to ask why it gets a panther?
Imo even a headless panther would be to much panther already.
 

Patresi

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This is a review and detailed measurements of the Monoprice Hybrid Tube Power and Headphone Amplifier. It is on kind loan from a member who sent it to Monoprice to be fixed twice. It costs US $199 from Monoprice direct. I can't find it on Amazon but there is a "Rockville" amp that looks identical and it goes for even less at US $149.

When I first reached for this amplifier, I thought it was a high-end, $1000 headphone tube amp or something. Imagine by shock that it turned out to only cost $199 or even lower per above. They have nailed all the signature bling of a much more expensive amplifier:


In person it looks even better than it does in above picture (available light late at night). We have a rather heavy unit, with fine feeling volume control, VU meter and those signature rings around the tubes. Heck, it even came with plastic covering the plastic/wood looking sides! I don't understand the economics of these things at all. Do they grow them in dirt and dig them and ship them? Can't imagine anyone building these from scratch yet selling them thousands of miles away for so little money.

The one usability I didn't like is lack of detent for the tone controls at 0 dB. I sort of eyeballed it in the middle.

The power button has a nice sold feel, belying the cost of this unit.

I won't cover the rest of the unit (including its Bluetooth functionality) here and will post a review from Z that explains it all.

Here is the back panel in case you are interested:


Let's get into the measurements and see how it performs.

Audio Measurements
I didn't test the bluetooth functionality leaving me with standard RCA input which is labeled as CD. This is our dashboard with 2 volt input and power adjusted to be 5 watts using 4 ohm load:

View attachment 25966

Where to start.... First there is all that hum and power supply noise. I tried grounding the input to it and while that reduced the 60 Hz hum, it made the rest of the spectrum worse so I left it alone. Still, that is not the worst of our problems. That lies in very high levels of harmonic distortion. And no, it is not a "tube distortion of 2nd harmonic." It is distortion at all harmonics! THD+N and hence SINAD puts it in dismal category and at the bottom of the list:

View attachment 25967

After creating these two slides I went back to my measurement software, only to notice things had gotten worse:

View attachment 25968

One channel was clipping on and off, bringing the THD+N to whopping 10%. It is asynchronously clipping. I captured and created the above slides and went back to the measurement software only to see this now:

View attachment 25969

Now both channels are busted! Can you spell garbage? I knew you could....

Humoring ourselves, and bringing every bit of motivation, I continued the testing with frequency response:

View attachment 25970

Good thing I am not the type to bang his head against the wall or I would have a concussion about now. I get that there is tone control but the channels don't match either.

The owner wanted to know about noise. Z review says the hum is there on power on. This is what I measured it half-way through testing:
View attachment 25971

And SNR:
View attachment 25972

The amplifier is advertised as having 50 watts of power. But the owner told me it is 25 watts which is much closer to the truth:

View attachment 25973

We are getting 1% distortion at 20 watts.

Intermodulation distortion picture is not pretty:
View attachment 25974

Conclusions
The monoprice hybrid tube amplifier nails the looks and aesthetics. The mechanical engineer and material procurement people deserve an A. The electronics designer know, gets a failing grade if he though this is a hi-fi product. Poor guy though was likely told to build this for nothing.

Congratulations are in order then for Monoprice to have produced probably the most faulty, and poorly measuring audio product I have tested to date. This would be good as a conversation piece on your desk and that is about it.

NOT recommended.

------------
As always, questions, comments, recommendations, etc. are welcome.

Good news: the pink panther strike is over! So my favorite model is back to posing business as you see in the review picture. I like to take the whole gang out for dinner (steak and lobster) to celebrate. Please help fund that by donating generously using:

Patreon: https://www.patreon.com/audiosciencereview), or
upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
Thank you for your wonderful report. I was thinking of purchasing one of these until I read your report.
 

MacCali

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I know this has been dead for ages, but I actually picked this unit up from monoprice on clearance. According to them the staff members were using on their setup, so they basically got it for free, but it wasn’t for them to keep. Again this is what I was told.

So they were selling it for 20 dollars, can’t say it’s amazing, but to be honest even for a piece of junk I really like the tube sound this garbage produces. No idea if the tubes had been rolled or not, but as your recent review would indicate tube rolling can not fix poor design.

But yea for 20 dollars I can’t complain honestly, and don’t plan on chucking it either. But ironically for something that measures so bad I find it quite odd that it’s not audible and also I get no hum on my speakers either. No clue what’s going on to be frank.

The only thing I can add, which would I assume make things work, is my volume is set at 95% on the unit and I control the volume with my phone usually at 60% on my phone it sound fine.
 
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