I'm not saying it cant do it. Maybe it can. My speakers are full range so while the bass is 'visible' at 11hz.. I get no punch to very low bass notes with my speakers. I added a few subs and a plate amp. Very happy with the sound. I am in the Houston Audiophile Society and more than a few people have commented that out of all the members systems they have heard, mine sounds best for the money invested. Using a chipamp that is not very different from what you are using. LM3886 vs LM3875. I dont think the chip is the problem here. Probably that punch you desire needs higher voltage rails to push more current and ultimately higher power into your speakers in those bass notes. To sustain that high current you need bigger PSU caps.
i had bad experience with adding capacitors to the existing psu caps. while they give you extra mid bass punch, the low bass punch increment is not as significant as the mid bass. this results in worse tonality overall 🙁
Hi Peter, just building your kit now.
I only have a 40v-0-40v transformer at the moment, and notice this is the top of the chip's recommended voltage, with warnings about .
Any concerns/recommendations here ?
Thx,
Jimchan
I only have a 40v-0-40v transformer at the moment, and notice this is the top of the chip's recommended voltage, with warnings about .
Any concerns/recommendations here ?
Thx,
Jimchan
This is chassis mounted laminated core centre tapped secondary giving 40v-0-40v ac direct from the transformer - perhaps too high ? (used in a previous amp)
you can even use 50-0-50V CT transformer, and you still get away with it. see the datasheet LM3875 - High-Performance 56W Audio Power Amplifier the maximum voltage swing is 84V
but remember, you have to adjust the value of the supply capacitors voltage accordingly
The absolute maximum supply voltage |V+| + |V-| is 84Vdc when signal is present.
This will be exceeded using a 0,30,0,30Vac mains transformer.
A 30Vac or 35Vac or 40Vac or 50Vac transformer cannot be used with a normal PSU to power any of these National Chipamps.
This will be exceeded using a 0,30,0,30Vac mains transformer.
A 30Vac or 35Vac or 40Vac or 50Vac transformer cannot be used with a normal PSU to power any of these National Chipamps.
Thx Andrew.... will have to leave the existing transformer on the shelf.
I have found the thread regarding power supplies for Gainclones, so will read up 🙂
I have found the thread regarding power supplies for Gainclones, so will read up 🙂
LiFePO4 power for chip amp?
I built Peter's LM3875 kit and have been enjoying it ever since. Now, I have an idea to build it into a battery powered integrated amp with a low voltage tube preamp stage. I am thinking of using a 25.6v LiFePO4 battery pack to power both the chip amp and tube stage directly, without any voltage regulation. The battery pack would hit 28.8V peak when fully charged, then drop to around 25.6V during the majority of its discharge cycle. The pack will incorporate a simple circuit that shuts off the power at 16V.
Does anyone see a problem with doing this with the LM3875?
I built Peter's LM3875 kit and have been enjoying it ever since. Now, I have an idea to build it into a battery powered integrated amp with a low voltage tube preamp stage. I am thinking of using a 25.6v LiFePO4 battery pack to power both the chip amp and tube stage directly, without any voltage regulation. The battery pack would hit 28.8V peak when fully charged, then drop to around 25.6V during the majority of its discharge cycle. The pack will incorporate a simple circuit that shuts off the power at 16V.
Does anyone see a problem with doing this with the LM3875?
I've been running one of my amps from batteries for over a year. They were 6x 12V Panasonic cells providing approx +/-39V . Didn't observe any long term problems.
Mr Daniels, I have recently bought and assembled your LM3875 kit, chassis is in the making and I am trying to decide to give my amp a volume pot or a buffered volume control, what do you reckon?
I allready have a tiny opamp volume buffer from SKA Audio, needing only a psu for it, or simply put in a 50k Alps? I really don't want to spend too much money on the pot. If it sounds good its good enough 🙂
I allready have a tiny opamp volume buffer from SKA Audio, needing only a psu for it, or simply put in a 50k Alps? I really don't want to spend too much money on the pot. If it sounds good its good enough 🙂
Peter, So how did the amp sound when powered by batteries? I can't imagine the battery power supply would make any appreciable improvement in sound quality, (My amp sounds terrific) but I can imagine the "flavor" of the sound could change somewhat, maybe making it even more agreeable. Batteries don't cost that much. Is this worth pursuing?
Lower noise floor?
I'm guessing that battery power will lower the noise floor. I'll report back to the thread when I've cot mine up and running. I am going to try an Aikido LV tube preamp stage in front of the chip amp. Planning to run both it and the amp on a 26.5VDC LiFePO4 pack. I just can't imagine how rectified power can possibly be as clean as pure battery power. I've heard arguments on both sides, but ultimately, you've got to try it yourself to find out.
I got on this battery kick when I built a linear power supply for my Squeezebox Touch. Amazing difference, even when using the digital outputs, and it got me thinking. Next, I tried running my tube preamp (an Elekit TU-875), which came with a switching wall wart power supply, on a LiFePO4 battery pack. The improvement was staggering. I was honestly not prepared for such an improvement.
I'm guessing that battery power will lower the noise floor. I'll report back to the thread when I've cot mine up and running. I am going to try an Aikido LV tube preamp stage in front of the chip amp. Planning to run both it and the amp on a 26.5VDC LiFePO4 pack. I just can't imagine how rectified power can possibly be as clean as pure battery power. I've heard arguments on both sides, but ultimately, you've got to try it yourself to find out.
I got on this battery kick when I built a linear power supply for my Squeezebox Touch. Amazing difference, even when using the digital outputs, and it got me thinking. Next, I tried running my tube preamp (an Elekit TU-875), which came with a switching wall wart power supply, on a LiFePO4 battery pack. The improvement was staggering. I was honestly not prepared for such an improvement.
im in the process of building one of these and im a little stuck. i am wondering if i need isolated rca jacks when mounting on a aluminum enclosure or would regular ones without the isolation washers do. i have a pair of uninsulated from a previous project that i didn't need them for so i don't want to have to order new ones if i don't have to.