"The amp will work with 2ohms if you don't push it too much. It will need good heatsinking though."
The above line right or wrong. I am going to try it. 12-0-12 5 Amp transformer is easy to buy. So I am going to power up 18-(+/-)VDC. Bridging with ESP's bridging adaptor. Any advices welcome...
The above line right or wrong. I am going to try it. 12-0-12 5 Amp transformer is easy to buy. So I am going to power up 18-(+/-)VDC. Bridging with ESP's bridging adaptor. Any advices welcome...
About LM1875
Hi,
I am really interested in LM1875 build and its performance. Don't go below 4ohms with LM1875. Better if you drive 8ohms speaker with it. I prefer 8ohms. Even 4 ohms will produce too much heat at around 18(+-) supply and prformance will dramatically change with voltages below 15 volts and above 20v. Think about how much heat will be produced at 2 ohms speaker load? LM1875 are designed for at least 4ohms speakers. On the other hand, using a high impedance load (8ohm speakers) will also give you a little increase in bass level as compared to other audio frequency notes (This sounds pleasant and its my personal experience. Your opinions are still reserved.). NOTE: Never operate LM1875 without the heat sinks even with no input signal condition. IC will get damage easily and soon.
I prefer 18-0-18 Transformer (GURU is the best) 5Amp with LM1875 Stereo build.And 8ohms Speaker.The choice is yours.
And, have you heard anything about ground loops? If you really wanna built a good, stable and trouble free completely silent and clean output power amplifier with no noise and hum. I suggest you to go with the vero board instead of any PCB. You cannot achieve 100% star grounding pattern with any PCB build. LM1875 is a low number components circuit design which can easily be build on a veroboard. A large veroboard for a stereo build which will cost you around 30Rs. The choice is again yours.
Thanks, let me know about your progress regarding this project. I wanna know about the performance of this working project soon.I have heard that this amplifier delivers the sound quality near to that of the Class A amplifier if configured and build properly.Infact,
i wanna build one myself but not getting a time with my daily buisy schedule.
Hi,
I am really interested in LM1875 build and its performance. Don't go below 4ohms with LM1875. Better if you drive 8ohms speaker with it. I prefer 8ohms. Even 4 ohms will produce too much heat at around 18(+-) supply and prformance will dramatically change with voltages below 15 volts and above 20v. Think about how much heat will be produced at 2 ohms speaker load? LM1875 are designed for at least 4ohms speakers. On the other hand, using a high impedance load (8ohm speakers) will also give you a little increase in bass level as compared to other audio frequency notes (This sounds pleasant and its my personal experience. Your opinions are still reserved.). NOTE: Never operate LM1875 without the heat sinks even with no input signal condition. IC will get damage easily and soon.
I prefer 18-0-18 Transformer (GURU is the best) 5Amp with LM1875 Stereo build.And 8ohms Speaker.The choice is yours.
And, have you heard anything about ground loops? If you really wanna built a good, stable and trouble free completely silent and clean output power amplifier with no noise and hum. I suggest you to go with the vero board instead of any PCB. You cannot achieve 100% star grounding pattern with any PCB build. LM1875 is a low number components circuit design which can easily be build on a veroboard. A large veroboard for a stereo build which will cost you around 30Rs. The choice is again yours.
Thanks, let me know about your progress regarding this project. I wanna know about the performance of this working project soon.I have heard that this amplifier delivers the sound quality near to that of the Class A amplifier if configured and build properly.Infact,
i wanna build one myself but not getting a time with my daily buisy schedule.
Last edited:
I am planning a similar build on proto board, first amp build (not counting cmoy on breadboard and proto board). Had a quick question about the caps attached to the +-Vcc. these need to be done on both the channels separately? Can I do this on the psu board itself or do i need to do this close to the ic. I understand I need to keep all the fb stuff close to the pins. any other useful tips for doing a p2p build. For now i am planning to use 15v 3a EI core trafo. I might run both 4 ohms or 8 ohms speakers in future.
Thanks
At my beginning stage I have used lot-off veroboard. A good sound quality can be achieve with it. @gotte advised me for tracks should be insulated with ground. Even I have searched professional circuit build like this.
I did not get good advice where LM1875 can work well with 2R load. I have suspended this project.. If some expert member allow to build, I would start again..
At my beginning stage I have used lot-off veroboard. A good sound quality can be achieve with it. @gotte advised me for tracks should be insulated with ground. Even I have searched professional circuit build like this.
I did not get good advice where LM1875 can work well with 2R load. I have suspended this project.. If some expert member allow to build, I would start again..
For a 2ohms speaker load the amplifiers are effectively seeing a 1ohm speaker load.
If one accepts that a standard chipamp is OK into an 8ohms speaker load. Then the 1ohm loading would require 8 in parallel giving a 16chip BPA for your 2ohms speaker.
Is that worth trying when you could use an lme498xx chip and a couple (or maybe 3pr) of output pairs?
If one accepts that a standard chipamp is OK into an 8ohms speaker load. Then the 1ohm loading would require 8 in parallel giving a 16chip BPA for your 2ohms speaker.
Is that worth trying when you could use an lme498xx chip and a couple (or maybe 3pr) of output pairs?
It takes 8 chips per each channel. It is a pair of 4-chip parallel amplifiers.
That is a gigantic mess.
TDA7294 and TDA7293 has a similar sound. There is a ready made TDA7293 parallel amplifier designed for easily driving 4 ohm speakers. That one simple little 2xTDA7293 board is perhaps more doable than an 8 chip LM1875 board.
The TDA chipamps are also current strangled.
There is only so much output device in a chipamp. Fit in two devices for a quasi complementary output stage and there is little room left for the rest of the IC.
All chipamps based on the extended To220 package will always have an output stage current limit that is low compared to a discrete output stage using far more "tab" area.
There is only so much output device in a chipamp. Fit in two devices for a quasi complementary output stage and there is little room left for the rest of the IC.
All chipamps based on the extended To220 package will always have an output stage current limit that is low compared to a discrete output stage using far more "tab" area.
There is an escape plan that doesn't require ballast resistors for paralleling. There might be enough current capacity that way.
The LM1875 is also very dynamic which is great until you find out it is really hard to parallel that thing beyond 2x, almost enough to drive a modest size 4 ohm speaker and still needs a current dumper/limiter protection at the power circuit as a cheat. Thus "don't bridge" is excellent advice.
Just to confirm, are you saying the TDA7294 sounds similar to the LM1875?
I am saying that is doable.
Similarity
I would use 330uF power caps on any of those chips (in addition to regular power board, of course). This works well for TDA7294 and LM1875 alike, and the tone is quite a bit similar.
Discrepancy
I would set the TDA7294 to medium gain because it is a miller comp amp wherein if you increase the gain, quality decreases proportionately. That inconvenience may incur the need of a preamp for computer, phone and digiplayer. Conversely, LM1875 is capable of high gain without a problem.
And, the MyRef project shows how to override the tone of the LM3886 with a small signal op-amp and in this case the "sound of" is the small signal op-amp that serves as pilot--nesting types give much better tone than a regular LM3886 or omission based gainclone.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.