Preamplifier Board, DROK HIFI Audio Pre-amplifier Module AC 15V-18V Preamp Circuit Board Adjustable Volume Regulation Controller Knob with OPAMP Socket & Transparent Acrylic Shell

This amp puts out decent sound quality up to 2PM. The bass and treble are awesome features. When nothing is playing it uses only 2W, the power consumption won't go over 10W until 12oclock. Only issue for me is even when the power switch is OFF, the caps are still discharging so when I connect the power source, it creates a spark. In one instance it zapped me good. I hate getting shocked! No there is nothing wrong with my power adapter, it works fine with other instruments. After further inspection, the designer should've installed the power switch between the power connector and the rest of the circuit NOT after the capacitors which allowing it to charge and discharge. If you don't believe me look at your red LED even when the unit is off, it's still lid up.

I am using this Bluetooth amp to power a T-COIL induction hearing loop at a friends house. I made the loop which is wrapped around her couch and have it connected to one of the outputs of this amp. The input is bluetooth from the television, or smartphone.The amp has plenty of gain, and runs the coil perfectly. I am using a discarded 19.2 V laptop power supply. The amp runs warm, but not hot. The loop consists of 180 feet of #22 solid core copper wire (telephone type). This has a resistance of about 4 to 6 ohms, and an impedance of 16 or more ohms at 10,000 Hz. The amp has no problem powering it as if it were a speaker. The coil is connected to one of the speaker outputs. I have nothing - no load - on the other speaker output.She can listen to the TV directly with her hearing aids thru the T-COIL setting on her aids. The TV speaker is muted, so she is not disturbing her neighbors and the sound clarity and fidelity is excellent.The acrylic case is nice, but after making several repeat orders of this item, many of them came with the front part of the case cracked and broken. It is cosmetic only, the amp inside worked fine. The unit was packaged in the usual DROK bubble wrap pack, which seemed to be in perfect condition. The shipping from amazon was also fine.Several of the amps had alterations - ie version 2.0 Multiple ventilation holes were drilled above the heat sink, and an On-OFF push button power switch were added. The Bluetooth identifier was changed - the new amps worked perfectly also.The volume cannot be adjusted unless it is connected and playing audio. Once the unit is playing audio, the volume can be adjusted evenly from very soft to loud in nice even steps.I put labels on the buttons. Play, pause, forward, backward, volume up, volume down. As with many DROK products, there is no documentation. I copy the pictures and descriptions from the website, which are usually sufficient.The laptop style power connector is great, plus a power supply connector is provided for attaching + and - leads. I have used the amp down to about 5 volts and to 19.2 volts. It runs warm at an idle at 19.2 volts, with no significant heating during operation.There are 2 thumb switches to control the gain, but you have to disassemble the case to get at them. I experimented, and the amp can be made to be very high gain. 2 switches allow for 4 gain settings. The default is the lowest setting, which is plenty loud.The unit automatically reconnects upon power up. It does have a power up beep sequence that lasts about 1 second. It is tolerable and better than voice. A blue light indicates a connection, and an alternating blue and red light indicates no connection and it automatically enters pairing mode.The great application of this amp / T-COIL is that most older and current hearing aids support T-COIL reception. This amp provided me what I needed to complete this DIY hearing loop project. Because it is Bluetooth, the amp can be located in proximity to the T-COIL, and not have to be near the audio source.

Amazing little, and I mean small, amplifier. Using it as a speaker (RCA Bookshelf speakers) driver for my desk top computer, powered by a former laptop power supply, regulated 20v 3amp capability, draws 0.07 amps at 20.4 volts, dc standby, and no noticeable increase driving speakers at a normal sound level. Fits very comfortably under the monitor, easily within reach. Requested documentation for reference as none was included in original package, but promptly received when requested. Small LED red light to let you know it is "on" but not intrusive in light intensity.

Perfect little gadget!I recently went wireless on all my indoor speakers with a Sonos setup. However, I had two mounted JBL outdoor speakers that are still great and serve their purpose. Seeing as how Sonos does not offer an outdoor speaker yet I wanted to keep these but no longer had my monster receiver to hook them up. Found this little unit and decided to give it a go. Works perfectly and supplies enough power for the sound I need. I just plugged in an Apple airport express and stream via AirTunes. So happy to find an easy solution. I’d recommend this unit.

I was surprised to hear this amp for the first time. Even though I don't need this much power, having it available added distortion-free peaks and a very clean sound.

I use this little amp to power a pair of small speakers in a 'waiting area'. Basically, I need to have some 'elevator music' going in the background. True, I don't demand a LOT form this amp. However, I am happy w/ the quality. The speakers I have is nothing HiFi. However, I would say sound is clean enough as to satisfy most of the laymen. Honestly, if you are a audiophile kinda person, why are you buying this $40 amp? :-)All in all, I am very happy w/ what I paid!

looks interesting. unfortunately one channel played louder than other. I could not a/b it with other preamps i havebecause of discrepancy. I have ordered another and will write a review when received. I have had good luck with drok productsand hope second one works correctly. board looks laid out well and has on off switch(rarity for sure !) also has mid freq. adjustment. runs of of 16 volt ac trans

Heavy distortion, minimal power, not worth it over cheaper alternatives.

I received this board in the mail yesterday, today I went to bench test it and it didn't even switch on.

AMPS DID NOTHING BUT MAKE MY SOUNDS A WHISPER?!I BOUGHT 2 UNITS THEY BOTH ARE SUPER LOW VOLUME?! I tried 12V 3A and 24V 5A, nothing boosted the volume.

Converted an old 1930's radio with this device to use bluetooth worked excellent. Easy connection no problems.

I bought it expecting it to be decent, but it only worked the first time. It has been half an hour in my hands, I've tried different speakers, different power sources but still...

I purchased 6 of these units and within 8 months half of them were producing distortion and had to be returned.

I am using for my business it is on 24/7 works perfectly

Class d amp. Neat little if needing to a subwoofer that doesn't have it's own built-in amp.

I wish this had an auxiliary in but it connects quick and the sound is good

Used in a trailer to amplify music with a (separate) bluetooth connector when I was camping. Worked great.

Nice little amp, but df oes clip at higher volumes