Here's the board in 3-D:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
rnoble said:
I don't see a problem with 300VA trafo to support 3 channel of GC.
The heatsink size should be fine too.
If the fuse blows, just replace it with a bigger one. I find the biggest problem with fuses blowing, the inrush current at start up. In my case 3A fuse is not big enough, but again, I'm running it at 120V AC from mains.
Vuamp2 said:
not really. I attached a pdf of the final files that were sent to the board manufacturer (Advanced Circuits) last week, and they are 80% done now, in the screening phase where they apply the silkscreen. Seems like they could possibly arrive here next week.
I will start taking orders soon.
--
Brian
to the poster of the VA vs Power
VA -- this is RMS voltage multiplied by RMS current. however some elements will store energy for later use. this means not all energy is used each cycle and thus power is less then V*I in (some) AC systems.
if you pay an electric bill, you can see how much energy you use vs how much you store/supply. this is "power factor" and should be close to 1.0. if it falls below something like 0.95 you will be chraged...
VA -- this is RMS voltage multiplied by RMS current. however some elements will store energy for later use. this means not all energy is used each cycle and thus power is less then V*I in (some) AC systems.
if you pay an electric bill, you can see how much energy you use vs how much you store/supply. this is "power factor" and should be close to 1.0. if it falls below something like 0.95 you will be chraged...
Brain,
I am sure that both Peter and you are correct. I just want to make sure that we are taling the same thing....
Post #215 posted by Brian show there is a small trace connects between pin 14 and 20. I don't see any trace between pin 14 and 18.... am I just don't read these image correctly?
I am sure that both Peter and you are correct. I just want to make sure that we are taling the same thing....
Post #215 posted by Brian show there is a small trace connects between pin 14 and 20. I don't see any trace between pin 14 and 18.... am I just don't read these image correctly?
Vuamp2 said:Brain,
I am sure that both Peter and you are correct. I just want to make sure that we are taling the same thing....
Post #215 posted by Brian show there is a small trace connects between pin 14 and 20. I don't see any trace between pin 14 and 18.... am I just don't read these image correctly?
It was a typo on my part. You were correct about it being between 14 and 20. I am sorry for the confusion.
--
Brian
Hi jiawu232-
digi01 has this thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=38506
And you can email him through the forum.
I have ordered a set of his boards and his ZEN headphone amp and am awaiting their arrival.
digi is a GREAT person to deal with.
Best of luck!
Thanks,
Troy
digi01 has this thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=38506
And you can email him through the forum.
I have ordered a set of his boards and his ZEN headphone amp and am awaiting their arrival.
digi is a GREAT person to deal with.
Best of luck!
Thanks,
Troy
I have started accepting pre-orders for the LM4780 kit. See my thread on the AVB here:
http://www.diyaudio.com/forums/showthread.php?postid=482310#post482310
The new website is up at:
www.chipamp.com
--
Brian
http://www.diyaudio.com/forums/showthread.php?postid=482310#post482310
The new website is up at:
www.chipamp.com
--
Brian
Audio Analogue's Primo Integrated Amp
Sam Tellig reviewed the Primo by Audio Analogue in the June issue of Stereophile.
an excerpt:
As you turn the Volume knob or press Volume on the remote, an array of small LEDs tells you where you stand with the gain. Roberto Martini has done a superb job with the look of this gear. The potentiometer is a National Semiconductor LM1972 integrated resistor network, with no buffers. According to Marco — next time I shall interview Nadia — each channel uses two “power pack ICs” to deliver a rated 70Wpc into 8 ohms or 110 W p c into 4 ohms. “ Power packs?” “A power pack is an integrated circuit that can manage power,” Marco explained. “It’s a kind of power op-amp. We use the same one that Jeff Rowland uses in his Concentra integrated amp — the National LM3886T. “Power packs have advantages over discrete component circuits,” Marco continued. “They save space, save heat, are totally protected against overloads and short-circuits. Each power pack uses a pair of bipolar output transistors in a quasi-omplementary mode. The two power packs are then connected in a fully balanced bridge configuration. So neither the positive output post nor the negative output post is at ground voltage. ” “And this is important?” “Noise. Or lack there of. This type of circuit uses two identical power amplifiers per channel. One amplifier works with the input signal, while the other works with a mirror signal, the same as the original input signal but with polarity reversed. “ The speaker is connected between the two outputs of the two amplifiers.
The original signal drives the positive input of the loudspeakers while the mirror-image signal drives the negative input. The power supplies of each polarity float, with none of the
capacitor-charging current contamination of ground circuitry. “Power packs save space, as I said.
Using two small power-pack amplifiers per channel, we can obtain 70 Wpc. If we used one power -pack amplifier per channel, we’d get 20W. ” “ Marco, you say each power pack
contains two bipolar output transistors. Do you have NPN complemented with PNP?” Output transistors come in two flavors: neutral-positive-neutral (NPN) and positive-neutral-positive (PNP). Usually, one complements the other to make a matched pair. “Only NPN bipolar transistors are used within each power pack,” Marco replied. “This makes the power stage not quite symmetrical, a little like a tube stage. Maybe this explains why this particular power pack offers such good sound and some other power packs don’t. ” Purists can pooh-pooh integrated circuits. When you introduce the term opamp, many audio purists think of the crappy analog output stages of inexpensive CD players, where each op-amp might cost 5¢ or 10¢. How do you think they make the stuff so cheap? To get a handle on the Primo integrated, I didn’t prime the Primo CD player right away. Instead, I routed a Creek CD50 Mk.2 CD player into a new McIntosh MDA 1000 D/A converter ($8000), removing the latest McIntosh MC275 tubed power amp ($3500). Speakers were the Opera Callases — no time to fool around if I’m to beat the Milanese hi-fi paparazzi. They’ll first read about it here. Ha. All of this was blatantly unfair to the Primo CD player. I used an $8000 D/A converter into a $3500 tubed power amp and compared this combo to an $895 solid -state integrated that was built for size, convenience, and price . . . and good sound. I preferred the Mac MC275. You shouldn’t be surprised. What surprised me was how much I enjoyed the Primo integrated on its own terms. The Mac MC275 sounded tubed. Well, it is tubed. While the Primo integrated isn’t tubed, it sounded tube-like to a remarkable degree. What I love about the Primo integrated is its tonality — my main concern, really. Call it the Claudio factor — orecchie di pipistrello. Resolution was very good — not exceptional, but probably beyond what you might expect for $895. But the tonality was exceptional. Violins. Cellos. Tenor sax. Female voice. Opera — the genre, not just the loud-speaker company. With the Operas, this system was Italy in a box —
Sam Tellig reviewed the Primo by Audio Analogue in the June issue of Stereophile.
an excerpt:
As you turn the Volume knob or press Volume on the remote, an array of small LEDs tells you where you stand with the gain. Roberto Martini has done a superb job with the look of this gear. The potentiometer is a National Semiconductor LM1972 integrated resistor network, with no buffers. According to Marco — next time I shall interview Nadia — each channel uses two “power pack ICs” to deliver a rated 70Wpc into 8 ohms or 110 W p c into 4 ohms. “ Power packs?” “A power pack is an integrated circuit that can manage power,” Marco explained. “It’s a kind of power op-amp. We use the same one that Jeff Rowland uses in his Concentra integrated amp — the National LM3886T. “Power packs have advantages over discrete component circuits,” Marco continued. “They save space, save heat, are totally protected against overloads and short-circuits. Each power pack uses a pair of bipolar output transistors in a quasi-omplementary mode. The two power packs are then connected in a fully balanced bridge configuration. So neither the positive output post nor the negative output post is at ground voltage. ” “And this is important?” “Noise. Or lack there of. This type of circuit uses two identical power amplifiers per channel. One amplifier works with the input signal, while the other works with a mirror signal, the same as the original input signal but with polarity reversed. “ The speaker is connected between the two outputs of the two amplifiers.
The original signal drives the positive input of the loudspeakers while the mirror-image signal drives the negative input. The power supplies of each polarity float, with none of the
capacitor-charging current contamination of ground circuitry. “Power packs save space, as I said.
Using two small power-pack amplifiers per channel, we can obtain 70 Wpc. If we used one power -pack amplifier per channel, we’d get 20W. ” “ Marco, you say each power pack
contains two bipolar output transistors. Do you have NPN complemented with PNP?” Output transistors come in two flavors: neutral-positive-neutral (NPN) and positive-neutral-positive (PNP). Usually, one complements the other to make a matched pair. “Only NPN bipolar transistors are used within each power pack,” Marco replied. “This makes the power stage not quite symmetrical, a little like a tube stage. Maybe this explains why this particular power pack offers such good sound and some other power packs don’t. ” Purists can pooh-pooh integrated circuits. When you introduce the term opamp, many audio purists think of the crappy analog output stages of inexpensive CD players, where each op-amp might cost 5¢ or 10¢. How do you think they make the stuff so cheap? To get a handle on the Primo integrated, I didn’t prime the Primo CD player right away. Instead, I routed a Creek CD50 Mk.2 CD player into a new McIntosh MDA 1000 D/A converter ($8000), removing the latest McIntosh MC275 tubed power amp ($3500). Speakers were the Opera Callases — no time to fool around if I’m to beat the Milanese hi-fi paparazzi. They’ll first read about it here. Ha. All of this was blatantly unfair to the Primo CD player. I used an $8000 D/A converter into a $3500 tubed power amp and compared this combo to an $895 solid -state integrated that was built for size, convenience, and price . . . and good sound. I preferred the Mac MC275. You shouldn’t be surprised. What surprised me was how much I enjoyed the Primo integrated on its own terms. The Mac MC275 sounded tubed. Well, it is tubed. While the Primo integrated isn’t tubed, it sounded tube-like to a remarkable degree. What I love about the Primo integrated is its tonality — my main concern, really. Call it the Claudio factor — orecchie di pipistrello. Resolution was very good — not exceptional, but probably beyond what you might expect for $895. But the tonality was exceptional. Violins. Cellos. Tenor sax. Female voice. Opera — the genre, not just the loud-speaker company. With the Operas, this system was Italy in a box —
Thank You glennb!
glennb has done a fair amount of research into the LM4780. On his site,
http://home.pacific.net.au/~gnb/audio/lm4780.html
he points out that the LM4780 is 2 LM3886 dies on one chip.
Which leads me to:
glennb has done a fair amount of research into the LM4780. On his site,
http://home.pacific.net.au/~gnb/audio/lm4780.html
he points out that the LM4780 is 2 LM3886 dies on one chip.
Which leads me to:
Bridging the LM4780
After review of the posted 4780 boards along with the National app note, it appears to me that it can be configured in bridge mode with the following changes:
Jumper R7, R8 & R9
"Cross" R5 with R6, that is change one leg of R5 from GND to input and change one leg of R6 from input to GND.
It remains to determine the proper values for R1-R6.
I submit this for your review and look forward to your comments
After review of the posted 4780 boards along with the National app note, it appears to me that it can be configured in bridge mode with the following changes:
Jumper R7, R8 & R9
"Cross" R5 with R6, that is change one leg of R5 from GND to input and change one leg of R6 from input to GND.
It remains to determine the proper values for R1-R6.
I submit this for your review and look forward to your comments
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