2.1 Amp with woofer and two tweeters


I am building a system with the 2.1 Amp and my plan is to use a woofer and 2 tweeters crossed at 2700hz.

However when i set up the filters in ACP Workbench and do measurements it seems like there is something filtering my mono channel around 200hz causing a major dip up to the point where the tweeters take over. Is that how the 2.1 amp is made or is my issue elsewhere?

There is a low pass filter on the mono channel, I think at 400Hz which will start to roll off earlier than that. The mono channel is designed for a subwoofer which would normally crossover much lower. It is possible to remove it by desoldering a resistor. I’ll go through my notes and post it here shortly.


Thank you very much, would be highly appreciated.

This is the info I had which came from Joy at Arylic customer support - Kudos for a well functioning after sales technical support service. I made the modification and it worked. You’ll need a small soldering iron and a pair of tweezers to remove the surface mount capacitor.

There is a limitation on hardware of about 400hz. Here is a solution: This capacitor is now has value (47nF), and you can replace with smaller one for higher frequency, and remove it to disable the low pass filter.


Thank you! That seems very doable.
I find it to be an odd design decision to make a hardware limit when you have DSP in the amp. It just limits the usage of the amplifier with no benefit?

I expect it’s there to reduce high frequency analogue noise on the subwoofer channel when it’s running at high gain. It was fine for my project though so good luck.

BTW - I’m not sure exactly what you’re building of coruse - but crossing over from mono to stereo L&R at that high frequency risks losing stereo information on playback. Around 200Hz and lower the sound is omnidirectional hence the reason there’s only a single channel for the subwoofer with a high pass filter at 400Hz. Normally it wouldn’t affect things.

I will keep my fingers crossed :slight_smile: I do find the amp to be a bit noisy already though.

I am building a portable speaker so stereo is very limited due to the size of the speaker. I have room for either two 3 inch full ranges and a 4 inch sub or two tweeters and a 5.25 inch woofer. From my limited testing i did manage to get some stereo feeling even with the 2700hz crossover, so i think this is the best compromise.

It’s all about compromises. It sounds similar to one of my projects. 2x Dayton audio dma90 full range plus a tang band W5-1138SMF in a vented cabinet. I crossed over around 450Hz hence the problem. Very pleased with the result.

Good luck with yours


Looks great. Really dig the design and the W5 unit is wonderful in smaller builds.

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I just did some more testing and it seems that even when removing the capacitor there is still some filtering going on. I just tested on the 2.1 plate amp and this is my results. I used a sweep on the same speaker first connected to SUB channel and then to left channel. As you can see there seems to be something raising the response below 1k and then filtering out high nodes for the SUB channel. Do anyone have an idea on how to remove the 2nd filter on the sub channel? Can i desolder the capacitor below the one in the picture as well?

Just remove the pointed capacitor to remove the hardware filter, and the system should have no other filtering circuit.

Anyway, the SUB output is normally mixed output of left and right channel, and this process will affect the mid and high frequency response. Maybe you could set the output mode to L/R/L+R mono, then these 3 channels would have same outputs, and the testing result would be almost same.

Thank you for the reply. When i do the testing i only output to left channel. So guess it shouldnt matter if i change the output mode?

Just made the full speaker and it does seem that there is some hardware filter still even though i desoldered the capacitor in the picture. It drops after 1k.

This is on the 2.1 plate amp btw. Dont know if that changes things?

I just tested on the completed speaker with the tweeters disconnected and there must be something because look at this response:

This is without any filters on the speaker…

You can see how the speaker is supposed to act.

Thanks for the info about desoldering this cap. Now my tweeters only need to play above 2200Hz and will be saved from bad basses :loud_sound:

Hi I Have a amp 2.1 v1 which has been working quite well till recently. Now I don’t get any output from any of the speakers L ,R or SubW but the system responds to the app and the web browser. Any help to check the amplifier stage is very much appreciated