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Fountek (Rhyme Acoustic) active speaker A-100

Posted 24th July 2015 at 08:18 AM by panson_hk
Updated 28th July 2015 at 01:37 AM by panson_hk

I purchased a pair active speaker. This is manufactured by Fountek under the brand Rhyme Acoustic. The model number is A-100. It uses a 4" full-range driver with vented box. The electronic is contained in the right channel enclosure. The amplifier is LM4766 chipamp. The overall build quality is good. I just paid RMB 399.00 during its sales period. What a good deal!

Chinese product link is https://item.taobao.com/item.htm?spm..._u=od0rlto94d1 The frequency response shown in this product page does not match with that given the user's instruction of my pair. The curve shown in user's instruction does pretty much match with my initial listening impression: lack of treble.

I measured the speaker with my CLIO Pocket. Measurement shows left and right enclosure response are matched very well.

The last figure shows the left box (passive) driven by another amplifier. We can then see what filtering or EQ is used in the A-100 amplifier. It can be seen compensation of baffle step and boost in HF.

[Update 28-7-2015]
When I use another amplifier (no filtering/EQ) to drive the passive side, the speaker sounds more balanced. I think modifying the electronic is a must.
Electronic board photos added.
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Comments

  1. Old Comment
    panson_hk's Avatar
    The A-100 amplifier does not seem to do baffle-step compensation and HF boost. It does more likely attenuate 5 k to 15 k. At 9 kHz, the attenuation is about 6 dB.
    permalink
    Posted 24th July 2015 at 08:34 AM by panson_hk panson_hk is offline
  2. Old Comment
    abraxalito's Avatar
    They're using TL084 going on what's written in Chinese. Probably you could increase the working impedance to get better SQ from these opamps - that's been my experience with Taobao sourced active speakers.
    permalink
    Posted 25th July 2015 at 02:56 AM by abraxalito abraxalito is offline
  3. Old Comment
    panson_hk's Avatar
    How are you, Richard? Thanks for your sharing! I have not analyzed the electronic board of A-100.
    permalink
    Posted 27th July 2015 at 04:58 AM by panson_hk panson_hk is offline
  4. Old Comment
    abraxalito's Avatar
    Hi Panson, long time no chat! I'm fine, working on a portable headphone amp design at the moment.
    permalink
    Posted 27th July 2015 at 11:13 PM by abraxalito abraxalito is offline
  5. Old Comment
    panson_hk's Avatar
    A fully discrete one? Will you also design the outlook?
    permalink
    Posted 28th July 2015 at 01:19 AM by panson_hk panson_hk is offline
    Updated 28th July 2015 at 01:21 AM by panson_hk
  6. Old Comment
    abraxalito's Avatar
    No, not fully discrete - rather a hybrid with opamps for gain and a fully discrete output buffer.
    permalink
    Posted 28th July 2015 at 02:58 PM by abraxalito abraxalito is offline
 

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