Great, just to be safe
. Still really loving the amp but my new speakers need some more juice. Thanks for answering.I've completed one of your builds, Peter - it sounds beautiful. Thank you!
Unfortunately, I'm getting loud pops when I turn on/off a (very cheap) desk lamp. Obviously I should just get rid of/move the lamp, but I'd like to do something about mains filtering.
I remember Marantz offered a power amplifier with a (large, expensive) battery partner. Instead of batteries, what about using a bank of supercaps? Can we completely separate the amp from the mains like that?
I'm also getting phone signal noise - I'm going to put together some shielded interconnects - so if there's something else people would suggest? I've seen some questions on here recently but I must have missed a solution if there was one...
Unfortunately, I'm getting loud pops when I turn on/off a (very cheap) desk lamp. Obviously I should just get rid of/move the lamp, but I'd like to do something about mains filtering.
I remember Marantz offered a power amplifier with a (large, expensive) battery partner. Instead of batteries, what about using a bank of supercaps? Can we completely separate the amp from the mains like that?
I'm also getting phone signal noise - I'm going to put together some shielded interconnects - so if there's something else people would suggest? I've seen some questions on here recently but I must have missed a solution if there was one...
Try that: http://www.diyaudio.com/forums/audi...-kit-building-instructions-3.html#post1516522
Bank of supercaps instead of batteries won't work here.
Bank of supercaps instead of batteries won't work here.
Low sensitivity speaker
Hi Peter, have the amp up and running, impressed by the clear sound but not singing as it should.
Dc offset is good, less than 10mv and no hum from the speakers even though not using exact star ground as recommended.
The bass is crisp, but the midrange and treble is distinctly lacking. Have tried with iPad and the Dac, and similar impression. existing HarmonKardon amp gives a full sound but not the clarity.
I note now my speaker sensitivity is 86db, 8 Ohm. Could this explain?
Br, Jim.
Hi Peter, have the amp up and running, impressed by the clear sound but not singing as it should.
Dc offset is good, less than 10mv and no hum from the speakers even though not using exact star ground as recommended.
The bass is crisp, but the midrange and treble is distinctly lacking. Have tried with iPad and the Dac, and similar impression. existing HarmonKardon amp gives a full sound but not the clarity.
I note now my speaker sensitivity is 86db, 8 Ohm. Could this explain?
Br, Jim.
good question, but yes. Ribbon tweeter is giving a slightly harsh response. bass OK, but underpowered. Mid range lacking.
230VA transformer, single rectifier to two amp boards.
I will also double check the correct component placing/sizing, but I have checked all this before.
Should I try with large capacitors (snubber) ?
230VA transformer, single rectifier to two amp boards.
I will also double check the correct component placing/sizing, but I have checked all this before.
Should I try with large capacitors (snubber) ?
Bridged LM4780 Questions
I am building the LM4780 in bridged configuration with one transformer and rectifier board and two bridged amps and had a few questions. If my questions have already been covered, I apologize but I've looked and cannot find specific answers.
1. For star grounding, the OG on the amp boards are tied together with the middle of this connection grounded to the metal case enclosure. The PG+ and PG- on rectifier board are connected to this chassis ground as well. Is there anything connected to PG+ and PG- terminals on the amp boards?
2. Is the speaker output connected through both "OUT"s on the amp board? If so what is the polarity of each "OUT"?
3. Is the input connected to the amp board on both "IN"s? If so, what is the polarity of each?
Thanks in advance for any help.
I am building the LM4780 in bridged configuration with one transformer and rectifier board and two bridged amps and had a few questions. If my questions have already been covered, I apologize but I've looked and cannot find specific answers.
1. For star grounding, the OG on the amp boards are tied together with the middle of this connection grounded to the metal case enclosure. The PG+ and PG- on rectifier board are connected to this chassis ground as well. Is there anything connected to PG+ and PG- terminals on the amp boards?
2. Is the speaker output connected through both "OUT"s on the amp board? If so what is the polarity of each "OUT"?
3. Is the input connected to the amp board on both "IN"s? If so, what is the polarity of each?
Thanks in advance for any help.
Bridged configuration has been explained here (same as stereo setup): http://www.diyaudio.com/forums/audi...chip-amp-kits-dacs-chassis-13.html#post636565
Peter, thanks for the quick response. I've looked at Post#246 and the LM4780 Amplifier Schematic but I'm still not 100% sure how to connect the inputs and outputs for bridged configuration.
Is this right:
My input signal + wire goes to both "IN"s on amp board and my input signal - wire goes to both "SG"s on amp board?
Both "OUT"s from amp board go to speaker + terminal and "OG" on amp board goes to speaker - terminal?
Thank you for your time.
Is this right:
My input signal + wire goes to both "IN"s on amp board and my input signal - wire goes to both "SG"s on amp board?
Both "OUT"s from amp board go to speaker + terminal and "OG" on amp board goes to speaker - terminal?
Thank you for your time.
The kit, in bridged configuration, will only work with balanced signal: positive goes to IN, negative goes to the other IN, ground connects to SG, speaker is connected between two OUTs. For unbalanced to balanced conversion you can use transformer: http://www.diyaudio.com/forums/audi...kit-building-instructions-21.html#post1712724
For more info check also those links:
http://www.diyaudio.com/forums/audio-sector/76609-most-advanced-gainclone-amp-yet.html
http://www.diyaudio.com/forums/audi...kit-building-instructions-68.html#post2432391
Balanced Signal - Blue Room wiki
For more info check also those links:
http://www.diyaudio.com/forums/audio-sector/76609-most-advanced-gainclone-amp-yet.html
http://www.diyaudio.com/forums/audi...kit-building-instructions-68.html#post2432391
Balanced Signal - Blue Room wiki
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Correct.Thats how I did it anyway.No hum or other noises.And the earth from the IEC connector.
Just getting started with enclosure
Hello Peter and all,
I will be building a 3875 Premium kit and a LM4780 Parallel kit, both using separate PS's inside one enclosure.
I have 3/8" thick x 10"L x 5"H aluminum front & back panels and side panels that are 3/8" thick x 6"L x 5"H. Inside ID's will be 9-1/4" W x 6"D.
I have 1/8" thick x 2"W x 8"L copper plate for attaching to the front and back aluminum panels, and have extra copper of the same dimension to solder between the front and back panels to act as a mounting plate and heat sink for the amp boards. The copper piece to be soldered can be soldered flat or vertical (ie: on the 1/8" edge).
Top and bottom of enclosure will be made of wood with some holes for ventilation.
Questions:
1) Adequate copper for heat sinking with the 3 pieces of copper, (remember 2 pieces of copper are attached to 3/8" aluminum plate).????
2) Can the rectifier boards be attached to the copper plate that the amp boards are attached to or is it better to attach to the aluminum side panels or to the bottom wood panel.
3) For grounding purposes can aluminum be used or do I need a steel ground post attached.
3a) If the steel ground post is needed can it be attached through the bottom wood or on the side aluminum panels or copper/aluminum on the front & back panels.
3b) Would it be better to attached a steel plate to the bottom wood to aid in grounding rather than 3 or 3a.
Thanks for the help
Myles
Hello Peter and all,
I will be building a 3875 Premium kit and a LM4780 Parallel kit, both using separate PS's inside one enclosure.
I have 3/8" thick x 10"L x 5"H aluminum front & back panels and side panels that are 3/8" thick x 6"L x 5"H. Inside ID's will be 9-1/4" W x 6"D.
I have 1/8" thick x 2"W x 8"L copper plate for attaching to the front and back aluminum panels, and have extra copper of the same dimension to solder between the front and back panels to act as a mounting plate and heat sink for the amp boards. The copper piece to be soldered can be soldered flat or vertical (ie: on the 1/8" edge).
Top and bottom of enclosure will be made of wood with some holes for ventilation.
Questions:
1) Adequate copper for heat sinking with the 3 pieces of copper, (remember 2 pieces of copper are attached to 3/8" aluminum plate).????
2) Can the rectifier boards be attached to the copper plate that the amp boards are attached to or is it better to attach to the aluminum side panels or to the bottom wood panel.
3) For grounding purposes can aluminum be used or do I need a steel ground post attached.
3a) If the steel ground post is needed can it be attached through the bottom wood or on the side aluminum panels or copper/aluminum on the front & back panels.
3b) Would it be better to attached a steel plate to the bottom wood to aid in grounding rather than 3 or 3a.
Thanks for the help
Myles
Andrew,
Thanks for the information about the corrosion.
Peter Daniels, maybe you can chime in as I know you have used copper attached to aluminum for heat sinking purposes on some of your amps.
Also Peter, could you comment on whether the reticfier board can be attached to a wood base, or would aluminum be better.
Thanks again,
Myles
Thanks for the information about the corrosion.
Peter Daniels, maybe you can chime in as I know you have used copper attached to aluminum for heat sinking purposes on some of your amps.
Also Peter, could you comment on whether the reticfier board can be attached to a wood base, or would aluminum be better.
Thanks again,
Myles