Hi
hmm...thats the reason i do not like the pot in the signal chain.
yes its could be that the steady position at the pot is getting crunch after a while.
if you us an pre amp why you use a volume pot in the "power amp"?...but this is your comfort and your decision
you can de-install the pot and use the signal by the rca directly at the amp board as we have done in the other thread.--> see attachment. rca- cable- board
chris
Thanks Chris
I think I had the amp vol set below max because I was confused about its clipping behaviour. I now know that it can be left wide open and using preamp for volume control. My mistake.
Yes I could take out the pot but wanted it to be an integrated amp for most of its intended use. Was using preamp with low output source and inefficient speakers.
Sure it could control the volume but at max volume the speaker output is too low so I used a 5x gain preamp.
Hi Dunk02
Relax....
.....dont feel pushed....its a hobby
i mean that your source should have a RCA connector and this you can connect to the RCA at your amp. then connect the hot wire of the first channel to the amp + and the othe cable to GND.
this you should repeat at the other channel. zoom in in my pic at the previous post)
chris
Relax....
.....dont feel pushed....its a hobbyi mean that your source should have a RCA connector and this you can connect to the RCA at your amp. then connect the hot wire of the first channel to the amp + and the othe cable to GND.
this you should repeat at the other channel. zoom in in my pic at the previous post)
chris
really?
your source has such a small output level??
i used with this LM1875 a 4ohm 81db efficiency speaker and it works. not ultra loud but enough to stop after 3 minutes.
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Hi Dunk02
Relax....
i mean that your source should have a RCA connector and this you can connect to the RCA at your amp. then connect the hot wire of the first channel to the amp + and the othe cable to GND.
this you should repeat at the other channel. zoom in in my pic at the previous post)
chris
Thanks Chris. I am chillin’ ��
I see how you have eliminated the pot. You could have included a pot and a bypass switch and have a dual purpose amp for use with or without a preamp? That was my original thought as I am still tinkering with speakers and sources and not wanting to commit to one configuration or another.
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This was a complete DIY hack using LM1875 boards. The inputs come from 3.5mm jack or RCA sockets directly to the pot and then to the two amplifier boards. Nothing tricky in the low voltage signal path.
My experience is probably the same as yours just did not want to be operating the amp near max power without any headroom before onset of clipping with loud transients.
Very COMPACT..... best to buy the case last 😂at page 9 the first pictures start.
he has a very compact design
Hi Dunk02
This is not what i mean. its enough without distortion.
at post #89 you wrote:
My intention is to mostly have it connected to an Apple Airport Express via a FiiO DAC (just for fun). My DIY Helium Micro Monitors may be the speakers I will keep connected On my work bench
The amp boards performance has been discussed in several places on the web and I probably won’t do much more testing, however here are some observations:
> @ 3/4 volume on iPhone through AEx and amp volume at 1/2 gives me nice listening volume in a large room with the larger bookshelf speakers
So what i mean is that your FiiO DAC should have 1,5V output (about 1Vrms) when you handy is at 3/4 max and that is for this amp enough. i did some measurements with 600mVrms- 650mvRms if i remember right and then i got clipping (max of the amp). so for me the pot is not needed. the volume control can be done by your apple.
chris
This is not what i mean. its enough without distortion.
at post #89 you wrote:
My intention is to mostly have it connected to an Apple Airport Express via a FiiO DAC (just for fun). My DIY Helium Micro Monitors may be the speakers I will keep connected On my work bench
The amp boards performance has been discussed in several places on the web and I probably won’t do much more testing, however here are some observations:
> @ 3/4 volume on iPhone through AEx and amp volume at 1/2 gives me nice listening volume in a large room with the larger bookshelf speakers
So what i mean is that your FiiO DAC should have 1,5V output (about 1Vrms) when you handy is at 3/4 max and that is for this amp enough. i did some measurements with 600mVrms- 650mvRms if i remember right and then i got clipping (max of the amp). so for me the pot is not needed. the volume control can be done by your apple.
chris
at page 9 the first pictures start.
he has a very compact design
Thanks Chris
I could experiment with that before installing the new pot.
I also have turntable phono stage, DAP, Chromecast/Fiio DAC; all connected through a source switch-box
Would there be any issues with adding signal input RCAs that go directly to the amplifier boards while still having the volume pot connected? Like a “preamp in”.
Also, should the signal wires going to the two channels have the same matching lengths to reduce the likelihood of channel imbalance due to differences in impedence?
Also, should the signal wires going to the two channels have the same matching lengths to reduce the likelihood of channel imbalance due to differences in impedence?
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