Hi all,
I believe that are a little incomprehension.
Naturally I speak of differences among revA and revC always with the same stereo version PCB.
I have not studied the differences with the Monoblock of Russ.
In theory, in my circuit there are 2 rectifiers(PS), 2 LM3886, 1 relay.
In the monobolck is 1 rectifiers(PS), 1 LM3886, 1 relay.
Result: the monoblock has to absorb = My- 1ch + 1relay.
A thing that it may influence is that in my stereo version the PS AC is not in phase among the 2 channels, and the ELcap Rch and Lch are charge inverse ( es:+Vcc to Lch & -Vcc to Rch). This technique serves to distribute the charge current peaks of the ELcap, and is not used by any ( in audio ).
LM318:
revC = OL gain reduction from 110dB to about 65dB, OLBW after 50 hz to 20khz + 2pole comp. for HF oscillation control.
It changes out offset voltage, but on account of the new DC internal path, and new low DC OL gain...
The output offset voltage doesn't change (more) the total absorption...
Ciao
Mauro
I believe that are a little incomprehension.
Naturally I speak of differences among revA and revC always with the same stereo version PCB.
I have not studied the differences with the Monoblock of Russ.
In theory, in my circuit there are 2 rectifiers(PS), 2 LM3886, 1 relay.
In the monobolck is 1 rectifiers(PS), 1 LM3886, 1 relay.
Result: the monoblock has to absorb = My- 1ch + 1relay.
A thing that it may influence is that in my stereo version the PS AC is not in phase among the 2 channels, and the ELcap Rch and Lch are charge inverse ( es:+Vcc to Lch & -Vcc to Rch). This technique serves to distribute the charge current peaks of the ELcap, and is not used by any ( in audio ).
LM318:
revC = OL gain reduction from 110dB to about 65dB, OLBW after 50 hz to 20khz + 2pole comp. for HF oscillation control.
It changes out offset voltage, but on account of the new DC internal path, and new low DC OL gain...
The output offset voltage doesn't change (more) the total absorption...
Ciao
Mauro
Sorry I wasn't very clear.
My test was with the monobloc PCBs only, one pair in REV A and one pair in REV C.
Idle current draw for a single channel of the REV A amp is roughly 30ma higher than the equivalent REV C all other things being equal and all common parts being the same.
Now, I would not find it unusual for my amps to be simply trying to bewilder me.
Cheers!
Russ
My test was with the monobloc PCBs only, one pair in REV A and one pair in REV C.
Idle current draw for a single channel of the REV A amp is roughly 30ma higher than the equivalent REV C all other things being equal and all common parts being the same.
Now, I would not find it unusual for my amps to be simply trying to bewilder me.
Cheers!
Russ
mauropenasa said:
Correct.
The is AC current draw from two channels from one 24V 450VA dual secodary torroidal transformer.
The test was done using my single bench transformer.
This testing was done on the bench a few days ago. For normal use each channel has its own transformer.
One other note, it appear from the datasheet the LM3886 quiescent current can range from 50ma to 85ma so there is a 35ma potential difference. And that is for 28V rails, it is probably a larger swing for 33V rails. So I think my findings are within the margine for differences in chip quiescent current.
Cheers!
Russ
Mongo happy...better than candygram
I came home to find my Beta package was delivered.
I had requested some extras and was pleasantly surprised.
The detailing of the boards can't be appreciated in photos. I'm looking forward to stuffing them...probably have to wait 'til this weekend though.
Thanks Russ and Brian!
Mauro, I'm so glad you are still with us. I hope the development of your project has gone beyond your expectations. I need to let you know you have given me access to best sound system I've ever had. I look forward to the enjoyment it will bring. I also salute you for the strides you have made with the English language. I know it is a challenge and you have handled it well.
Ciao,
I came home to find my Beta package was delivered.
I had requested some extras and was pleasantly surprised.
The detailing of the boards can't be appreciated in photos. I'm looking forward to stuffing them...probably have to wait 'til this weekend though.
Thanks Russ and Brian!
Mauro, I'm so glad you are still with us. I hope the development of your project has gone beyond your expectations. I need to let you know you have given me access to best sound system I've ever had. I look forward to the enjoyment it will bring. I also salute you for the strides you have made with the English language. I know it is a challenge and you have handled it well.
Ciao,
amp heat - the math
Russ and Mauro,
Thanks for the feedback on the heat dissipation of the different amps. Here's my understanding of why my Rev A amp is heating up a bit more than my LM3875 gainclone. I notice the following differences:
LM3875 amp:
--- Power supply is +-24VDC
--- Idle current is 35ma (from data sheets)
--- Idle power = 1.7W per chip
LM3886 amp:
--- Power supply is +-30VDC
--- Idle current is 45ma (from datasheets) and perhaps 15ma higher according to Russ for the Rev A
--- Idle power = 2.7W to 3.6W / chip
So its understandable that the heatsink in my new amp is hotter than the old one. Perhaps my little block of copper is a bit marginal.
Once I get the Rev C parts I'll see if that makes any difference as Russ noted or if its truly no difference.
By the way, the amp is starting to sound quite nice. Last night I wasn't sure if it sounded as good as the Hicap snubberized LM3875 amp but this morning it seemed to have at least equalled the LM3875 amp or perhaps surpassed it. More as it develops.
---Gary
Russ and Mauro,
Thanks for the feedback on the heat dissipation of the different amps. Here's my understanding of why my Rev A amp is heating up a bit more than my LM3875 gainclone. I notice the following differences:
LM3875 amp:
--- Power supply is +-24VDC
--- Idle current is 35ma (from data sheets)
--- Idle power = 1.7W per chip
LM3886 amp:
--- Power supply is +-30VDC
--- Idle current is 45ma (from datasheets) and perhaps 15ma higher according to Russ for the Rev A
--- Idle power = 2.7W to 3.6W / chip
So its understandable that the heatsink in my new amp is hotter than the old one. Perhaps my little block of copper is a bit marginal.
Once I get the Rev C parts I'll see if that makes any difference as Russ noted or if its truly no difference.
By the way, the amp is starting to sound quite nice. Last night I wasn't sure if it sounded as good as the Hicap snubberized LM3875 amp but this morning it seemed to have at least equalled the LM3875 amp or perhaps surpassed it. More as it develops.
---Gary
YAAAAAY!!!!!!!
Hi All,
Thanks Russ...
I was sleeping and when I woke up; to my pleasant surprise, I found the PCBs lying by my bed... UNTOUCHED by the customs department.
am awaiting Brian's part kit... and then im going to populate the board... lemme see if i majke a photo-journal of this..
take care,
M
Hi All,
Thanks Russ...
I was sleeping and when I woke up; to my pleasant surprise, I found the PCBs lying by my bed... UNTOUCHED by the customs department.
am awaiting Brian's part kit... and then im going to populate the board... lemme see if i majke a photo-journal of this..
take care,
M
Re: amp heat - the math
Hi Gary,
Just to follow up for you and everyone else. I am now convinced as mauro suggested that the real difference I was seeing between my Rev As and my Rev Cs in terms of idle current draw was due to normal chip variance.
I tested my theory by taking two new LM3886s and putting them in my Rev Cs. Now it is only 12ma difference between Rev A and Rev C. The Rec Cs still draw a little more, but I can see that statistically it is a draw.
Cheers!
Russ
GaryB said:
Hi Gary,
Just to follow up for you and everyone else. I am now convinced as mauro suggested that the real difference I was seeing between my Rev As and my Rev Cs in terms of idle current draw was due to normal chip variance.
I tested my theory by taking two new LM3886s and putting them in my Rev Cs.
Now it is only 12ma difference between Rev A and Rev C. The Rec Cs still draw a little more, but I can see that statistically it is a draw. Cheers!
Russ
Thanks Ed.
Yes, the results of my work have gone over my expectations.
I thought about an exchange of ideas among "experts" of planning ( that are missing nearly at once by the thread ), instead there are many happy DIYs. Better ( the experts are boring and without imagination...).
I have not found never the time to thanking everything those has believed in this work, because even I appreciate the compliments and know that "My_Ref" is becoming "Our_Ref".
Your enthusiasm is the only motive that does me stay in the audio forums.
Is not my English that improves, but my copy Your expressions...
Hi Russ,
It is tolerances of Idle LM3886, that even changes with the temperature, and in the stereo version ( 2 LM3886 ) some about 5-20 mA it's may consider normal...
Ciao
Mauro
Well I am not really really keeping close tabs on how many are complete, but I know at least this many:
REV A Stereo: 8 completed amps as far as I know.
REV C monobloc(single side & beta 2 side): 7 completed stereo pairs(including mine).
That is just based on people who I know personally have told me of their finished amps. Probably some have finished silently, or are close to being complete.
I just want to thank everyone for giving me the opportunity to learn so much. Though, it only shows me I have so much yet to learn.
Mauro, you have tought me a lot, and you have always been very gracious. You have earned my respect and my friendship.
Cheers!
Russ
REV A Stereo: 8 completed amps as far as I know.
REV C monobloc(single side & beta 2 side): 7 completed stereo pairs(including mine).
That is just based on people who I know personally have told me of their finished amps.
Probably some have finished silently, or are close to being complete.I just want to thank everyone for giving me the opportunity to learn so much. Though, it only shows me I have so much yet to learn.
Mauro, you have tought me a lot, and you have always been very gracious. You have earned my respect and my friendship.
Cheers!
Russ
Completed "Mauros"
Hi all,
Russ, depending somewhat on the definition of complete you can probably make that "at least 9"
My REV A Mauro is electrically complete and sounding very nice indeed - remarkable clarity even when compared to some very much more costly amps.
Mechanically it's far from finished but since it works fine spread out on the bench I'll probably let it play as it is for now.
Cheers
Dave
Hi all,
Russ, depending somewhat on the definition of complete you can probably make that "at least 9"
My REV A Mauro is electrically complete and sounding very nice indeed - remarkable clarity even when compared to some very much more costly amps.
Mechanically it's far from finished but since it works fine spread out on the bench I'll probably let it play as it is for now.
Cheers
Dave
Hey Brian,
I'll let you know about the labeling as well. I did notice and my first impulse was "sweet!" The packaging was snug and secure.
A note on my experience with the imaging of RevA: during initial use I was treated to a (strange) audio experience. The soundstage was WAY outside of my speakers, favoring the left side. My speakers and listening position form an equilateral triangle. Some of the music seemed to be coming from 30 degrees outside the left speaker. It made me consider "What's wrong?". With 30 hours (or more) on the amp the sound has centered.
I can hear individual notes, the nuance a singer imparts to the song, fretting of bass strings, a clear decay of percussion, individual voices rise from the chorus and the silence between notes is deeper, better defined. Ohhh, the things I've missed until now. The list goes on and on...
I'll let you know about the labeling as well. I did notice and my first impulse was "sweet!" The packaging was snug and secure.
A note on my experience with the imaging of RevA: during initial use I was treated to a (strange) audio experience. The soundstage was WAY outside of my speakers, favoring the left side. My speakers and listening position form an equilateral triangle. Some of the music seemed to be coming from 30 degrees outside the left speaker. It made me consider "What's wrong?". With 30 hours (or more) on the amp the sound has centered.
I can hear individual notes, the nuance a singer imparts to the song, fretting of bass strings, a clear decay of percussion, individual voices rise from the chorus and the silence between notes is deeper, better defined. Ohhh, the things I've missed until now. The list goes on and on...
rabstg said:
Guess what I got today...
Well let me start by asking this:
Brian, do you have any spare time on your hands? You obviously don't have children.
For all others, My word, I have never seen such nice neat packing and labeling of components.
.Words simply can not discribe the packing, labeling and organizing job Brian did.
Oh, and the boards look first rate too. Nice job Russ.
I will assemble the amp this week and report back next with pictures and the assembly documentation.