Peter support is an incredible added value (I built two Audiosector kits with great success).
Northernsky
That's what I like to hear!
The vendor got back to me regarding my LM3886 woes and is kindly sending me replacement components for free, hopefully I will get it working at some point. I would definitely like to get the Audio Sector kit too though, it would be good to compare them in my system and always having a spare amp is a good thing imo.
The vendor got back to me regarding my LM3886 woes and is kindly sending me replacement components for free, hopefully I will get it working at some point. I would definitely like to get the Audio Sector kit too though, it would be good to compare them in my system and always having a spare amp is a good thing imo.
Last edited:
I can not believe what amazing value for money these kits are. Anyone who thinks these guys are expensive should try pricing the components up 
I thought about buying the LM3875 Premium boards and sourcing the same premium spec components here in the UK, i got about half way through the component list when the price including boards exceeded the cost of the full premium kit including postage.
An easy decision, i'll have start saving for the full kit and I have the knowledge that my hard earned will go to good people
Just got to finish my LM3886 my preamp and my passive tone control builds first
I thought about buying the LM3875 Premium boards and sourcing the same premium spec components here in the UK, i got about half way through the component list when the price including boards exceeded the cost of the full premium kit including postage.
An easy decision, i'll have start saving for the full kit and I have the knowledge that my hard earned will go to good people
Just got to finish my LM3886 my preamp and my passive tone control builds first
Hi!
I made these photos just to share my chassis to my chip amps.
The front and real panels, as well as the covers will be made of plexiglass, white, translucid.
I will also use some damping materials that are not in the photos.
I will post more photos of these amps assembled, when it's ready.
This was sanded in the end with 800 sandpaper and finished with the skin of my hands with a very fine olive oil!
click on the link - if it doesn't work, make copy and paste in your browser.
https://www.dropbox.com/sc/c979uon9m6et723/0IM--9ZRQx
these boards are not exactly for these transformers, it is just to make the pictures
I made these photos just to share my chassis to my chip amps.
The front and real panels, as well as the covers will be made of plexiglass, white, translucid.
I will also use some damping materials that are not in the photos.
I will post more photos of these amps assembled, when it's ready.
This was sanded in the end with 800 sandpaper and finished with the skin of my hands with a very fine olive oil!
click on the link - if it doesn't work, make copy and paste in your browser.
https://www.dropbox.com/sc/c979uon9m6et723/0IM--9ZRQx
these boards are not exactly for these transformers, it is just to make the pictures
Last edited:
Build an amp.com
As a matter of fact, I ordered from Uriah, the preamp,
thanks for thr tip
As a matter of fact, I ordered from Uriah, the preamp,
thanks for thr tip
Ok, just to be sute that I will not mess up :
From Gaincard , Brown (Pin 1): +VDC
Black/White (Pin2 and 3): +-VAC tied together at ground.
Blue (Pin 4): -VDC
Can anyone please see the image and tell me if I am right?
Thank you!
http://www.hostingpics.net/viewer.php?id=833819img051.jpg
From Gaincard , Brown (Pin 1): +VDC
Black/White (Pin2 and 3): +-VAC tied together at ground.
Blue (Pin 4): -VDC
Can anyone please see the image and tell me if I am right?
Thank you!
http://www.hostingpics.net/viewer.php?id=833819img051.jpg
Last edited:
PROBLEM with caps...
Hello everybody. Finished my kit, and I think I made à mistake.
On the power supply board, I soldered 2 caps on the holes marked C1 and C2. 2200uF.
On the amp board, I soldered the 100uF caps
Do I leave the caps on the PS board, I mean the big 2200uF, or do I remove them, knowing that I won't solder the other parts of the snubber ??????
Hello everybody. Finished my kit, and I think I made à mistake.
On the power supply board, I soldered 2 caps on the holes marked C1 and C2. 2200uF.
On the amp board, I soldered the 100uF caps
Do I leave the caps on the PS board, I mean the big 2200uF, or do I remove them, knowing that I won't solder the other parts of the snubber ??????
Hello,
i'm a first-time diyer and was hoping someone could help me to understand if what i want to do will work:
I'm planning to build LM4780 kit in bridged/balanced, dual mono confuguration and use it with Buffalo IIIse DAC + Legato output stage. From what i understand - Legato uses variable resistors to trim and zero out DC offset (no caps), but common mode DC remains (at balanced outputs). If I understand correctly - as long as there's no ground for it - common-mode DC is not a problem, or am I missing something?
I'm hoping to build a system with no decoupling caps (or bal>se opamps) in the path
Also, is DC offset for both halves of LM4780 is close enough that i should get very little DC in bridged mode, or it varies heavily?
i'm a first-time diyer and was hoping someone could help me to understand if what i want to do will work:
I'm planning to build LM4780 kit in bridged/balanced, dual mono confuguration and use it with Buffalo IIIse DAC + Legato output stage. From what i understand - Legato uses variable resistors to trim and zero out DC offset (no caps), but common mode DC remains (at balanced outputs). If I understand correctly - as long as there's no ground for it - common-mode DC is not a problem, or am I missing something?
I'm hoping to build a system with no decoupling caps (or bal>se opamps) in the path
Also, is DC offset for both halves of LM4780 is close enough that i should get very little DC in bridged mode, or it varies heavily?
If the two phases of the balanced input have identical DC offset then the (perfect) balanced to unbalanced receiver will ignore the DC offset and output a plain unbalanced signal without any offset.
That raises two questions.
a.) is the DC offset alwaysbalanced?
b.) how close to perfect is the bal to unbal receiver?
That can be measured at the output. Measure the output offset at the speaker terminals.
Does it vary?
That raises two questions.
a.) is the DC offset alwaysbalanced?
b.) how close to perfect is the bal to unbal receiver?
That can be measured at the output. Measure the output offset at the speaker terminals.
Does it vary?
I don't have it all yet - just planning ahead...
I guess in my case "balanced to unbalanced receiver" is one half of LM4780 chip (3886 to be exact). So if I feed each 3886 with balanced signal with identical DC offset it will be zeroed-out inside the amp and i'll only get amp's own offset in the end which needs to match (more or less) offset of it's out-of-phase 3886 brother, right? It should still be better than resulting DC of unbalanced LM3875 amp for example...
Can I completely zero-out DC at dac's output? Manual says i can (except for common-mode DC).
I know Twisted Pear own LM4780 amp works with Legato I/V stage, just wanted something simpler with no additional opamps in signal path...
I guess in my case "balanced to unbalanced receiver" is one half of LM4780 chip (3886 to be exact). So if I feed each 3886 with balanced signal with identical DC offset it will be zeroed-out inside the amp and i'll only get amp's own offset in the end which needs to match (more or less) offset of it's out-of-phase 3886 brother, right? It should still be better than resulting DC of unbalanced LM3875 amp for example...
Can I completely zero-out DC at dac's output? Manual says i can (except for common-mode DC).
I know Twisted Pear own LM4780 amp works with Legato I/V stage, just wanted something simpler with no additional opamps in signal path...
each half of the dual chip gets it's own signal phase plus the DC offset.
The output is an amplified version of the signal plus offset.
The two opposite halves have a signal and an inverted signal, these add to give a double level signal to the output device.
The two DC offsets are in phase and these cancel in the combined signal fed to the output device.
It's the balanced to unbalanced combination that amplifies the differential input signal and cancels the common mode input signal (which will include interference).
The output is an amplified version of the signal plus offset.
The two opposite halves have a signal and an inverted signal, these add to give a double level signal to the output device.
The two DC offsets are in phase and these cancel in the combined signal fed to the output device.
It's the balanced to unbalanced combination that amplifies the differential input signal and cancels the common mode input signal (which will include interference).
LM4870 runs hot idle
Hi guys,
just putting together an LM4870 amp in parallel mode using Audiosector pcb's.
Parts are same value as suggested by Peter. DC is 35V. It runs much too hot idle, each rail on each chip pulls 0.5A!
I've checked and double checked, but can't find the reason. Any help is welcome!
Thanks,
Abel
Hi guys,
just putting together an LM4870 amp in parallel mode using Audiosector pcb's.
Parts are same value as suggested by Peter. DC is 35V. It runs much too hot idle, each rail on each chip pulls 0.5A!
I've checked and double checked, but can't find the reason. Any help is welcome!
Thanks,
Abel
Thanks guys!
Ya, that's right, after two minutes I can start cooking on it! 70W for two physical chips.
I've connected an oscilloscope and there's a 20Vpp sinus oscillation at around 250kHz. If I shorten the input, or even just connect a piece of cable to it, it stops. And current goes back to around 110mA per rail per physical chip.
The input consists of 22k to ground followed by 220ohm to each opamp in the chip.
Seems like in a normal setup the oscillation would not occur. But if it would not be there to begin with, I would be happier. Any suggestions?
Ya, that's right, after two minutes I can start cooking on it! 70W for two physical chips.
I've connected an oscilloscope and there's a 20Vpp sinus oscillation at around 250kHz. If I shorten the input, or even just connect a piece of cable to it, it stops. And current goes back to around 110mA per rail per physical chip.
The input consists of 22k to ground followed by 220ohm to each opamp in the chip.
Seems like in a normal setup the oscillation would not occur. But if it would not be there to begin with, I would be happier. Any suggestions?
Bal or SE?
I finally found suitable enclosure and thinking to order one of the kits to introduce myself to world of "simple" gainclones as well as convinient way to test balanced vs single ended outputs of my dac. But which one?
I have Buffalo III dac with discrete Legato output stage and wanted to try shortest signal path possible using integrated (ES9018) volume control to output directly to chipamp.
LM3875 is easiest choice, but it means i'll have to use dac's bal>se stage which consist of opamp followed by a buffer (lme49600) and their neg.feedbacks which doesn't make it as short and straight as balanced outputs to say bridged LM4780 which are also coupling caps free (If common-mode DC is not a problem, can null differential DC). Or maybe i can use paired LM3875 in bridged configuration?
My speakers are 95db and 6 ohm minimum so should be easy load for both?
I'd appreciate opinions/suggestions
I finally found suitable enclosure and thinking to order one of the kits to introduce myself to world of "simple" gainclones as well as convinient way to test balanced vs single ended outputs of my dac. But which one?
I have Buffalo III dac with discrete Legato output stage and wanted to try shortest signal path possible using integrated (ES9018) volume control to output directly to chipamp.
LM3875 is easiest choice, but it means i'll have to use dac's bal>se stage which consist of opamp followed by a buffer (lme49600) and their neg.feedbacks which doesn't make it as short and straight as balanced outputs to say bridged LM4780 which are also coupling caps free (If common-mode DC is not a problem, can null differential DC). Or maybe i can use paired LM3875 in bridged configuration?
My speakers are 95db and 6 ohm minimum so should be easy load for both?
I'd appreciate opinions/suggestions
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.