Hello everyone.
I have implemented a version of the LM3886 & ACEBass amplifier on the same circuit using the AudioPRO b1-45 circuit.
I saw an alternative called LEMF, has anyone implemented it? I would like to try it but I am not clear how to do it.
Thank you all.
I have implemented a version of the LM3886 & ACEBass amplifier on the same circuit using the AudioPRO b1-45 circuit.
I saw an alternative called LEMF, has anyone implemented it? I would like to try it but I am not clear how to do it.
Thank you all.
Could you please post the freq response of the electric signal going to the speaker from your special amp.
The FR will demonstrate the difference the circuit makes from the ordinary ruler-flat amp output with the speaker connected.
Thanks.
B.
The FR will demonstrate the difference the circuit makes from the ordinary ruler-flat amp output with the speaker connected.
Thanks.
B.
🙂
Thank you for replying.
Right now I'm moving house.
I would be curious to know the pros and cons of the two types.
I have read the KES but I cannot find the second part (in PDF) of Tim Mellow's study.
Thank you for replying.
Right now I'm moving house.
I would be curious to know the pros and cons of the two types.
I have read the KES but I cannot find the second part (in PDF) of Tim Mellow's study.
Here are some differences between ACE-BASS and LEMF:
LEMF uses feedback around the driver to increase or decrease the electrical damping and thus the apparent Q of the driver. This is combined with a variety of highpass filters around the driver resonance frequency to produce a series of vented box alignments.
ACE-BASS uses feedback around the driver to eliminate the voice coil resistance, Re. When this is zero, an electrical network on the input of the amplifier can combine with the electro-mechanical network and the filter can be used to influence the apparent values of the electro-mechanical elements, which are what determine all the near-resonance driver parameters. So ACE-BASS can modify both Qts AND Fs, and this can be employed in combination with any alignment you choose, sealed or vented, to "synthesize" a response you desire when the driver doesnt' have the necessary parameters a priori, or if those parameters would make the driver very inefficient, e.g. very low Fs.
On paper, the ACE-BASS system seems much more capable, however, it has the flaw that as the driver is put into use the voice coil heats up and Re increases over the "cold" value. Because the action of ACE-BASS relies on Re being cancelled totally or almost completely in order to function properly, as Re increases from heating the performance of ACE-BASS drifts and may become poor. Its a major shortcoming to what otherwise is a nice piece of work.
Both LEMF and ACE-BASS may cause instability and feedback. For the LEMF, this is the case when too much positive feedback is used to driver Qes lower. For ACE-BASS, positive feedback is used to eliminate Re, and if the circuit is configured to have a tad too much, you get runaway feedback as well. In practice, even when cold, ACE-BASS is typically only configured to null 85-90% of Re for this reason.
LEMF would be safer and easier for the DIYer to use, IMHO, although I have seen several ACE-BASS implementations in the past. Use positive feedback with care!
LEMF uses feedback around the driver to increase or decrease the electrical damping and thus the apparent Q of the driver. This is combined with a variety of highpass filters around the driver resonance frequency to produce a series of vented box alignments.
ACE-BASS uses feedback around the driver to eliminate the voice coil resistance, Re. When this is zero, an electrical network on the input of the amplifier can combine with the electro-mechanical network and the filter can be used to influence the apparent values of the electro-mechanical elements, which are what determine all the near-resonance driver parameters. So ACE-BASS can modify both Qts AND Fs, and this can be employed in combination with any alignment you choose, sealed or vented, to "synthesize" a response you desire when the driver doesnt' have the necessary parameters a priori, or if those parameters would make the driver very inefficient, e.g. very low Fs.
On paper, the ACE-BASS system seems much more capable, however, it has the flaw that as the driver is put into use the voice coil heats up and Re increases over the "cold" value. Because the action of ACE-BASS relies on Re being cancelled totally or almost completely in order to function properly, as Re increases from heating the performance of ACE-BASS drifts and may become poor. Its a major shortcoming to what otherwise is a nice piece of work.
Both LEMF and ACE-BASS may cause instability and feedback. For the LEMF, this is the case when too much positive feedback is used to driver Qes lower. For ACE-BASS, positive feedback is used to eliminate Re, and if the circuit is configured to have a tad too much, you get runaway feedback as well. In practice, even when cold, ACE-BASS is typically only configured to null 85-90% of Re for this reason.
LEMF would be safer and easier for the DIYer to use, IMHO, although I have seen several ACE-BASS implementations in the past. Use positive feedback with care!