Do you get good bass with 120VA? Although the recommended VA rating for this amp is 250-300 in this thread, based on my understanding from the datasheet of the LM3875 chip (I'm not sure I understand this stuff correctly), the amp will use a maximum of 5 amps at full power (with a mximum peak at 100 watts, the maximum amps used would be the square root of (2*100)/8ohms, formula 6). Why them recommend 10 amps (250VA at 25V)?
I used to work for a company that used a thermoelectric cooler in one of its products. The main reason to use such a cooler is if you need the cold side to be really cold, i.e. below ambient temperature (active chilling).
A thermoelectric cooler is very effective at moving heat from one side to the other, but the heat still has to go somewhere. It doesn't mitigate the need for a heatsink. If anything, it often requires an even larger heat sink to dissipate all the heat being moved.
Hi,
the continuous AC current rating of a transformer has no bearing on the maximum output current of a ClassAB amplifier.
That was the short answer.
The bass is full and tight.
I use 18-0-18V at 120VA per channel. This gives me just over 24V dc at the rails (off load). I use a T rated fuse to cope with the inrush current. Any more VA and I would need a soft start circuit.
I'm listening to the amp and thinking of adding more bass.
I read that the first hours of an chip amp sound great, then sound awful for a certain time and sound right later. Is this right? Mine is short on bass, but the high and mid seem very great...
How can I add bass? Is it with a low pass filter? If so, what is this? A circuit or a type of component? If it is a component, can someone suggest me a part from digikey.ca?
If it is a circuit, where can a find the diagram to build one?
Thanks
I read that the first hours of an chip amp sound great, then sound awful for a certain time and sound right later. Is this right? Mine is short on bass, but the high and mid seem very great...
How can I add bass? Is it with a low pass filter? If so, what is this? A circuit or a type of component? If it is a component, can someone suggest me a part from digikey.ca?
If it is a circuit, where can a find the diagram to build one?
Thanks
Hi,
read some of my discussion about Peter's choice of design decisions and how he chose to "tune" his implementation.
I have stated, but can't be sure, that Peter's implementation is specifically targeted at high efficiency speakers, that many of his customers don't and never will have.
In my opinion (and Peter won't want to hear it yet again) good bass can only come from an amp and PSU combination that is designed to deliver high AC currents while still delivering the voltage required to drive the speaker.
I have stated repeatedly how this can be achieved for normal sensitivity speakers, but Peter does not agree with me.
read some of my discussion about Peter's choice of design decisions and how he chose to "tune" his implementation.
I have stated, but can't be sure, that Peter's implementation is specifically targeted at high efficiency speakers, that many of his customers don't and never will have.
In my opinion (and Peter won't want to hear it yet again) good bass can only come from an amp and PSU combination that is designed to deliver high AC currents while still delivering the voltage required to drive the speaker.
I have stated repeatedly how this can be achieved for normal sensitivity speakers, but Peter does not agree with me.
The short answer would be: with an equalizer
We still don't know what is the rest of your system, so comments from Andrew above are completely worthless.
Andrew, check the reviews on my site as well 47Labs website to learn that the amp can work perfectly fine with low efficiency speakers as well.
And please stop constantly asking for a schematic, it's been posted on page 1 and this is the only amp implementation we are discussing in this thread.
Peter or anyone else,
i bought the audiosector Lm4780 kits and i am using them bridged now (balanced input). In total i use 4 amps for biamping a 2-way setup. I am very happy with the sound, but i was wondering if it is worth to try using a carlos Fm snubber on the low pass amps and leave the high pass amps according to the original kit. I have the caps available, BC components 15000uF, 40V would these be suitable?
thanx for any reply on this.
regards
Harold
i bought the audiosector Lm4780 kits and i am using them bridged now (balanced input). In total i use 4 amps for biamping a 2-way setup. I am very happy with the sound, but i was wondering if it is worth to try using a carlos Fm snubber on the low pass amps and leave the high pass amps according to the original kit. I have the caps available, BC components 15000uF, 40V would these be suitable?
thanx for any reply on this.
regards
Harold
Well, it's certainly worth a try and you should decide for yourself if snubber is preferred or not. The caps you have will be suitable.
Initially I was quite impressed myself, but later came to conclusion that snubber isn't my cup of tea. I noticed some other people had similar impressions.
I wrote about it here: http://www.diyaudio.com/forums/chip...ut-any-comments-suggestions-8.html#post581230
Initially I was quite impressed myself, but later came to conclusion that snubber isn't my cup of tea. I noticed some other people had similar impressions.
I wrote about it here: http://www.diyaudio.com/forums/chip...ut-any-comments-suggestions-8.html#post581230
Hello Peter,
i know i read this thread/post, that is wy i was asking since i have s split setup. Well since i have the capacitors, i will give it a try and post my impressions
thankx
The short answer would be: with an equalizer
We still don't know what is the rest of your system, so comments from Andrew above are completely worthless.
I use it with an Ipod or my computer with 6ohms speakers for the moment. They are not high quality speakers, but an average consumer speaker.
I use a Torroid from Plitron
300VA Custom Toroidal Power Transformer. Outputs: 18.00V @ 8.33A x 2
The torroid is made for 220V, and since I lived in Québec, I supply 2x115V for 230V, so I get around 23V-24V DC. I filled it with epoxy glue to mount it.
I follow exactly all the the steps in this tread. When no source is connect, I don't have any noise, just silence as if the amp is off. I use a 50k stereo potentiometer.
So, can I add bass? If it is with a low pass filter, how do I proceed?
Thanks
That's what I was suspecting, the lack of base is most likely not the "feature" of the amp but is due to an associated equipment. When you upgrade your source or speakers, the bass should come too, in a meantime, as suggested earlier, just use an equalizer feature on you digital front end to boost the bass: How to use the iPod Equalizer
Attachments
The Ipod equalizer doesn't do much. If I compare with my old Pionner from the same source, the Pionner has a lot more bass.
Can I add something or not? I may degrade the highs, but I dont mind.
Thanks
You should keep in mind that Pioneer is an integrated amp with a proper line stage and who knows how they voiced the circuit, it may indeed create impression of more bass, which not necessarily be accurate.
You can also add line stage to GC, maybe it's possible to use line circuit from Pioneer if it has PRE OUT connectors at the back.
You may as well Google for "bass boost circuit", there are plenty of them available.
You can also add line stage to GC, maybe it's possible to use line circuit from Pioneer if it has PRE OUT connectors at the back.
You may as well Google for "bass boost circuit", there are plenty of them available.
I've recently built a custom headphone amp based on LM3875 kit. The requirement was to have it fully balanced, preferably in dual mono configuration.
I used one of the custom toroids from toroidy.pl with amorphous core and 4 sets of secondaries at 22V AC ea. The power supplies are located on both sides and 2 LM3875 premium kits have been used in balanced configuration. I didn't do any changes to the kits with exception of replacing 680R resistors with 1k2 to lower the gain. Output is taken directly from between 2 amps.
Initially, we were using Noble pot, each deck across two phases of balanced signal, and it worked quite good, but later at customer request I changed it to Khozmo.
The preamp can handle only balanced sources and there are two sets of outputs, no speaker connection possible. The Integrated Amp chassis, with slight modifications worked very well here.
We tried few different headphone models and all worked perfectly fine. This is what customer thinks about the whole setup, especially after attenuator upgrade:
Immediately I could see the improvement in depth and clarity compared to the non-balanced pot. I can now ear the echos of the instruments and various sound layering. I really like the many possible volume adjustments. That was a good choice!!
I can say, and without a doubt, this attenuator is the best complement to your amp - a benchmark, what a difference!. For me, it is now my Holy Grail reference head amp!!
I can hear the music "raw emotion" and the artists own breaths, it's quite spectacular!! No way you can get near this on a 2ch system without dropping huge $$$'s
I use 20 clicks or 11 O'clock position for normal & sustained listening periods (with the HD800). The low level adjustment, precision and switch tightness is really, really nice.
By far my best attenuator, highly recommended and worth the $275 investment, you should try it yourself!
I used one of the custom toroids from toroidy.pl with amorphous core and 4 sets of secondaries at 22V AC ea. The power supplies are located on both sides and 2 LM3875 premium kits have been used in balanced configuration. I didn't do any changes to the kits with exception of replacing 680R resistors with 1k2 to lower the gain. Output is taken directly from between 2 amps.
Initially, we were using Noble pot, each deck across two phases of balanced signal, and it worked quite good, but later at customer request I changed it to Khozmo.
The preamp can handle only balanced sources and there are two sets of outputs, no speaker connection possible. The Integrated Amp chassis, with slight modifications worked very well here.
We tried few different headphone models and all worked perfectly fine. This is what customer thinks about the whole setup, especially after attenuator upgrade:
Immediately I could see the improvement in depth and clarity compared to the non-balanced pot. I can now ear the echos of the instruments and various sound layering. I really like the many possible volume adjustments. That was a good choice!!
I can say, and without a doubt, this attenuator is the best complement to your amp - a benchmark, what a difference!. For me, it is now my Holy Grail reference head amp!!
I can hear the music "raw emotion" and the artists own breaths, it's quite spectacular!! No way you can get near this on a 2ch system without dropping huge $$$'s
I use 20 clicks or 11 O'clock position for normal & sustained listening periods (with the HD800). The low level adjustment, precision and switch tightness is really, really nice.
By far my best attenuator, highly recommended and worth the $275 investment, you should try it yourself!
Attachments
""Immediately I could see the improvement in depth and clarity compared to the non-balanced pot. I can now ear the echos of the instruments and various sound layering. I really like the many possible volume adjustments. That was a good choice!!
I can say, and without a doubt, this attenuator is the best complement to your amp - a benchmark, what a difference!. For me, it is now my Holy Grail reference head amp!!
I can hear the music "raw emotion" and the artists own breaths, it's quite spectacular!! No way you can get near this on a 2ch system without dropping huge $$$'s
I use 20 clicks or 11 O'clock position for normal & sustained listening periods (with the HD800). The low level adjustment, precision and switch tightness is really, really nice.
By far my best attenuator, highly recommended and worth the $275 investment, you should try it yourself![/QUOTE]"""
Hmmmmmmm.... Sounds like ...... Hmmmmmmmmmm someone familiar...... Like Lamxxxcczator ??!!
Just Kidding. You're the man!!
I can say, and without a doubt, this attenuator is the best complement to your amp - a benchmark, what a difference!. For me, it is now my Holy Grail reference head amp!!
I can hear the music "raw emotion" and the artists own breaths, it's quite spectacular!! No way you can get near this on a 2ch system without dropping huge $$$'s
I use 20 clicks or 11 O'clock position for normal & sustained listening periods (with the HD800). The low level adjustment, precision and switch tightness is really, really nice.
By far my best attenuator, highly recommended and worth the $275 investment, you should try it yourself![/QUOTE]"""
Hmmmmmmm.... Sounds like ...... Hmmmmmmmmmm someone familiar...... Like Lamxxxcczator ??!!Just Kidding. You're the man!!
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