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Buying advice Amplifier (2.1, D-Class)

petfr

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Nov 9, 2022
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Hello . This is my first post in this forum and I need tips for a suitable 2.1 amplifier. This should be in my working room and I would like to operate it with various self-made speakers (mostly full range) with an active subwoofer (Numan - UniSUB). My current amplifier is an N22 from Audioengine. After reading this review, I thought it was time to look for something that sounded better. After reading the good reviews here, I bought a Douk Audio H7 (price: ~110 €) and immediately returned it because of a defective right channel. Unfortunately, as in the manufacturer's description , the two potentiometers do not regulate all outputs, but only the passive speakers. The so-called pre-out has a fixed level, at least on my H7. In conjunction with an active subwoofer, of course, an absolute no-go. I am now looking for an inexpensive and compact amplifier that controls the volume for both the passive speaker outputs and the subwoofer output. My existing subwoofer has RCA inputs (stereo).
 
I have a similar setup (2.1 including an active sub). I'm using the Fosi BT30D Pro.

Pros:
  • The line-out is a true "pre-out" -- it's output level is controlled by the volume knob.
Cons:
  • No high-pass filter.
  • The BT30D Pro subwoofer controls affect only the speaker-level (passive) sub output. They do not affect the pre-out.
  • Bluetooth SBC/AAC only. No LDAC, Apt-X, etc.
  • No Bluetooth authentication.
In short, I bought the wrong amp. It'd be fine if my sub were passive (I didn't buy it for its Bluetooth capabilities). It might work for you assuming you have some other method of high-pass filtering your main speakers.
 
I have a similar setup (2.1 including an active sub). I'm using the Fosi BT30D Pro.

Pros:
  • The line-out is a true "pre-out" -- it's output level is controlled by the volume knob.
Cons:
  • No high-pass filter.
  • The BT30D Pro subwoofer controls affect only the speaker-level (passive) sub output. They do not affect the pre-out.
  • Bluetooth SBC/AAC only. No LDAC, Apt-X, etc.
  • No Bluetooth authentication.
In short, I bought the wrong amp. It'd be fine if my sub were passive (I didn't buy it for its Bluetooth capabilities). It might work for you assuming you have some other method of high-pass filtering your main speakers.

Thanks for your answer . The only reason I asked my question in this forum was because the description of these Chinese class-D amplifiers does not always make it clear whether the subwoofer output is also regulated. Limiting the frequency response to relieve the load on the main speakers is of course also important to me. I was worried that I might have worded my question incorrectly here. Unfortunately there were no answers except for yours. But I was able to solve my problem myself. I now own a Rogersond Labs iA 255.1 .The unfortunately somewhat expensive shipping from California to Germany was extremely quick. The amplifier works to my complete satisfaction and sounds significantly better than my previous one.
 
I now own a Rogersond Labs iA 255.1 .The unfortunately somewhat expensive shipping from California to Germany was extremely quick. The amplifier works to my complete satisfaction and sounds significantly better than my previous one.

If I could go back in time and buy something different, that Rogersound would be my first choice. It's exactly what I need, though a variable hi-pass filter (instead of fixed at 90Hz) would be nice.

Presently I use EqualizerAPO to provide crossover. My active sub is connected to my PC's C/SUB audio jack and I've bypassed the sub's on-board filter (LFE mode). I've lost use of the Fosi BT30D volume knob -- it's only useful as a gain control for L & R -- but for now I can use the mixer in Windows 11.
 
Other than the RSL mentioned above, there aren't many options that provide a high pass filter unless you go full AVR. I think the NAD 3045, SVS Prime Base, and Bluesound Node are about it, and they are in a different price category.
 
I have a similar setup (2.1 including an active sub). I'm using the Fosi BT30D Pro.

Pros:
  • The line-out is a true "pre-out" -- it's output level is controlled by the volume knob.
Cons:
  • No high-pass filter.
  • The BT30D Pro subwoofer controls affect only the speaker-level (passive) sub output. They do not affect the pre-out.
  • Bluetooth SBC/AAC only. No LDAC, Apt-X, etc.
  • No Bluetooth authentication.
In short, I bought the wrong amp. It'd be fine if my sub were passive (I didn't buy it for its Bluetooth capabilities). It might work for you assuming you have some other method of high-pass filtering your main speakers.


I found these on Amazon inline rca high and low pass filters.

 

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