Monoprice 150 watt 605030 Amplifier Review

[cistercian]

I submitted this amp for review because it can deliver 360 wpc into 8 ohms when bridged; for $130 per channel that would be amazing. It tested within specifications (0.02% THD). Alas, too many other flaws such as the on all the time fan. Stay tuned for the next candidate soon!

I agree! The fan is not a good thing, and I did not even look at power bridged! The dollar/watt ratio bridged is epic.
For me the red flag is the excursion in distortion during warm-up. I sense low quality components/design and one of
the nice things about a good pro amp is the durability. Connection options in the rear are spartan but fine for the price.
I hope you score a home run next time!

 

[RayDunzl]

I checked all of my connections and distortion persisted. I almost didn't run the rest of my tests but decided to do anyway. As another 5 to 10 minutes passed, I noticed the performance had improved so I went back and re-measured the dashboard again:

I have never seen an amplifier improve by 11 dB after brief warm up.

Just to satisfy my intense (yawn) curiosity:

Measure it cold again...

Just to see if it was "warmup"

Or "break-in".

Or not reproduceable.

 

[Vasr]

I suggest you try one sometime with an open mind. If your mind is closed when listening you will likely end up hearing what you want and not what is.

These kinds of ad hominems only weaken your case. Disgusting.

 

[PeteL]

I submitted this amp for review because it can deliver 360 wpc into 8 ohms when bridged; for $130 per channel that would be amazing. It tested within specifications (0.02% THD). Alas, too many other flaws such as the on all the time fan. Stay tuned for the next candidate soon!

Strangely tough, it's not the specs on the Monoprice Website.where did you get this? Actually, they state 0.05% and this is what we get here. BUT, they specify Peak Power at twice the RMS (and twice what Amir tested) How did they come up with that?

 

[Chrispy]

Strangely tough, it's not the specs on the Monoprice Website.where did you get this? Actually, they state 0.05% and this is what we get here. BUT, they specify Peak Power at twice the RMS (and twice what Amir tested) How did they come up with that?

Marketing imagination?

ps It's not unusual to quote peak power at twice continuous.....

 

[RayDunzl]

BUT, they specify Peak Power at twice the RMS (and twice what Amir tested) How did they come up with that?

Find RMS voltage using Power and Ohms

Peak Voltage is 1.414 x RMS = 48.98239683804786V

1.414 being shorthand for the square root of 2

Recalculate using Peak Voltage and Ohms

http://www.sengpielaudio.com/calculator-ohm.htm

 

[PeteL]

Find RMS voltage using Power and Ohms

View attachment 83866

Peak Voltage is 1.414 x RMS

Recalculate using Peak Voltage and Ohms

View attachment 83867

Ah, yes, I see, but what does Amir's measurments mean, It's a rms mesurment but for short transients? Just finding the amplitude in volts and converting it to Watts don't add useful info.

 

[RayDunzl]

Ah, yes, I see, but what does Amir's measurments mean, It's a rms mesurment but for short transients?

I don't understand your question.

A sine wave with an RMS voltage of 1V has a Vpeak of 1.414V

They are the same thing, just labeled differently

It's one wave, power didn't change. Power is usually measured over time - the RMS value is used.

 

[PeteL]

I don't understand your question.

A sine wave with an RMS voltage of 1V has a Vpeak of 1.414V

They are the same thing, just labeled differently

It's one wave, power didn't change. Power is usually measured over time - the RMS value is used.

Yes, Peak power don't mean much in that sence. In this case. Let's forget what rms mean, I know that, I just tought that mentioning what it mean in term of VPeak is irrelevent. Amir measured 156 Watts into 4 ohms continuous and 166 Watts Peak, so only 10 watts Headroom for shorter burst. That's the value of PEAK power that matter and that is worth specifying. In the classic sense, this value tells us if there is a good bank of capacitors at the power supply. Or an another way of saying this is, if the dynamic range of the music, and the level of listening demand for momentarily demand more than the specified rms power, will it be hard clipping, or do you have some headroom and how much.

 

[amirm]

@amirm Any chance of a picture of the inside? I am wondering what chips this uses and other things?

This is being returned so I don't dare trying to open it and give them an excuse to refuse.

 

[RayDunzl]

Amir measured 156 Watts into 4 ohms continuous and 166 Watts Peak, so only 10 dBs Headroom

10dB headroom over 156W would equate to something more like 1560W.

---

24.97Vrms = 156W / 4 ohms
25.77Vrms = 166W / 4 ohms

Ratio of 25.77/24.97 = 1.032

 

[PeteL]

10dB would equate to more like 1560W.

---

24.97Vrms = 156W / 4 ohms
25.77Vrms = 166W / 4 ohms

Ratio of 25.77/24.97 = 1.032

View attachment 83873

Yes, wrote too fast, 10 watts means no headroom. edited

 

[amirm]

Amir measured 156 Watts into 4 ohms continuous and 166 Watts Peak, so only 10 watts Headroom for shorter burst.

I am using a standardized peak power measurement. They could be using anything they want without specifying such.

 

[Francis Vaughan]

When things are this cheap, as the old saw goes, it isn't a matter of how good the device is, but that it works at all. Most manufactures would have trouble delivering the case and connectors for the all up price here. If you were in the professional sound reinforcement game at an entry level you could afford to have a couple as reserve amps without thinking about it.
For driving a sub-woofer this would be hard to beat.
But,as Amir says, for a few dollars more they could sort out a few issues that render the device less than happy in a home environment. You can be sure that it has been value engineered down to the last cent. Every possible place a saving could be made will have been exploited.
If a teardown is possible, it would be most appreciated. Seeing where and how corners are cut would be most interesting.

 

[ROOSKIE]

These kinds of ad hominems only weaken your case. Disgusting.

I really have no case friend.
Just hoping you will try one out and see what you think - hopefully saving you and others a lot of money and worry about the little things.
Anyway you do what serves you best, there are many fun options in audio that is for sure. No end to the good times.

 

[ROOSKIE]

When things are this cheap, as the old saw goes, it isn't a matter of how good the device is, but that it works at all. Most manufactures would have trouble delivering the case and connectors for the all up price here. If you were in the professional sound reinforcement game at an entry level you could afford to have a couple as reserve amps without thinking about it.
For driving a sub-woofer this would be hard to beat.
But,as Amir says, for a few dollars more they could sort out a few issues that render the device less than happy in a home environment. You can be sure that it has been value engineered down to the last cent. Every possible place a saving could be made will have been exploited.
If a teardown is possible, it would be most appreciated. Seeing where and how corners are cut would be most interesting.

Since Amir can't open the copy he has I might just buy one and then I can post pics here. I am looking for a 100watt x2 budget amp to run directly off my phone-minidsp Hd-amp to power an additional system.
I actually think this amp specs well for that (compared with say a Chinese version of a TI chip amp) and the loud fan means nothing to me as I will just buy a quiet fan or try fanless. Total guess without seeing the guts but I highly doubt that fan does much for the amp at all. Likely runs just fine without in while not rack mounted.

 

[amirm]

Since Amir can't open the copy he has I might just buy one and then I can post pics here.

Please don't do this just yet....

 

[Blumlein 88]

I find it funny this is now considered a not very powerful amp. One with not many use cases. Here are the specs not so long ago for a Krell KSA 100.

Description: Power output: 100W into 8 ohms (20dBW), doubles with each halving of load impedance down to 1 ohm. Frequency response: 20Hz–20kHz, +0.0/– .1dB; 1Hz–150kHz, +0.0/–3dB. Distortion: <0.1% at 1kHz; <0.5%, 20kHz, full power. Slew rate: 100V/µs. Input sensitivity: 1.4V RMS. Gain: 26dB. Damping factor: >60. Input impedance: 47k ohms. Power consumption: 100W, idle; 1400W, full power.
Dimensions: 19" W by 8.5" H by 19.25" D. Weight: 80 lbs (net).
Serial number of unit tested: 32-20216.
Price: $5500 (1994); no longer available (2007). Approximate number of dealers: 55. Warranty: 5 years, parts and labor.
Manufacturer: Krell, 45 Connair Drive, Orange, CT 06477-0533. Tel: (203) 799-9954. Fax: (203) 799-9796. Web: www.krellonline.com.

Notice it has specs actually a bit below this Monoprice rig. And it did slightly exceed them in Stereophile testing, but only slightly. And these babies were $5500 13 years ago. The Krell would have pumped out more current into tough loads, would have been quiet without a fan, but other than that is about on par with the Monoprice offering. FR was more extended and flatter too.

https://www.stereophile.com/content/krell-ksa-100s-power-amplifier-measurements

 

[SpaceMonkey]

I find it funny this is now considered a not very powerful amp. One with not many use cases. Here are the specs not so long ago for a Krell KSA 100.

Description: Power output: 100W into 8 ohms (20dBW), doubles with each halving of load impedance down to 1 ohm. Frequency response: 20Hz–20kHz, +0.0/– .1dB; 1Hz–150kHz, +0.0/–3dB. Distortion: <0.1% at 1kHz; <0.5%, 20kHz, full power. Slew rate: 100V/µs. Input sensitivity: 1.4V RMS. Gain: 26dB. Damping factor: >60. Input impedance: 47k ohms. Power consumption: 100W, idle; 1400W, full power.
Dimensions: 19" W by 8.5" H by 19.25" D. Weight: 80 lbs (net).
Serial number of unit tested: 32-20216.
Price: $5500 (1994); no longer available (2007). Approximate number of dealers: 55. Warranty: 5 years, parts and labor.
Manufacturer: Krell, 45 Connair Drive, Orange, CT 06477-0533. Tel: (203) 799-9954. Fax: (203) 799-9796. Web: www.krellonline.com.

Notice it has specs actually a bit below this Monoprice rig. And it did slightly exceed them in Stereophile testing, but only slightly. And these babies were $5500 13 years ago. The Krell would have pumped out more current into tough loads, would have been quiet without a fan, but other than that is about on par with the Monoprice offering. FR was more extended and flatter too.

https://www.stereophile.com/content/krell-ksa-100s-power-amplifier-measurements

800 watts into 1 ohm. Not many amps can do this today.

 

[RayDunzl]

would have been quiet without a fan

Might have had a fan (or two)

http://home.ca.inter.net/~lloyd.maclean/Krell/Krell.htm