A lot better grip.
To early to really give a review, but after a little while hooked the recently finished Full versiion of Mauro's Evolution up to these 20 -20K wall shakers. This has paralleled LM3886 current pumps, four discrete diode bridges, and 80K of capacitance onboard. Plus a 400 VA transformer.
Much tighter bass, and seems to be even more velvety sounding than the Rev C. It is only maybe a 60 watt amp, but has a damping factor of 350. Seeed to grip those thuimping 13 inch drivers tighter.
But I am still waiting to try the TX0 amp also. And if you ask, I am putting two pairs of my A series Lowthers up for sale soon. I really like these 801 Matrix speakers.
George
To early to really give a review, but after a little while hooked the recently finished Full versiion of Mauro's Evolution up to these 20 -20K wall shakers. This has paralleled LM3886 current pumps, four discrete diode bridges, and 80K of capacitance onboard. Plus a 400 VA transformer.
Much tighter bass, and seems to be even more velvety sounding than the Rev C. It is only maybe a 60 watt amp, but has a damping factor of 350. Seeed to grip those thuimping 13 inch drivers tighter.
But I am still waiting to try the TX0 amp also. And if you ask, I am putting two pairs of my A series Lowthers up for sale soon. I really like these 801 Matrix speakers.
George
Attachments
Re: A lot better grip.
That's why B&W has stayed popular sooooo long.
I used my 805's on top and activly crossed them over to woofers (not subs) at 125Hz. Was sort of a bi-amped 801..
I LOVED them... But eventually the tweeter housing broke off from the kids.. Office would have been a much safer place.
I recycled the B&W mid into the new speakers... In my humble opinion, the B&W mid has been my favorite to date.. The SS used in the Wilson Watt is second and the old Focal 5" nomex is behind the SS only because Focal discontinued them.
Back on topic, any pictures of the evolution?
Panelhead said:
That's why B&W has stayed popular sooooo long.
I used my 805's on top and activly crossed them over to woofers (not subs) at 125Hz. Was sort of a bi-amped 801..
I LOVED them... But eventually the tweeter housing broke off from the kids.. Office would have been a much safer place.
I recycled the B&W mid into the new speakers... In my humble opinion, the B&W mid has been my favorite to date.. The SS used in the Wilson Watt is second and the old Focal 5" nomex is behind the SS only because Focal discontinued them.
Back on topic, any pictures of the evolution?
I will open it up
The front is in the lower picture, that is a 16 x 16 parmetal case. The black thing on the bottom of the stack.
The inside is nothing to brag about, Mauro sells the boards with most components already soldered in. The components he uses are all surface mount. It has regs to feed the LM318 this time. All the higher wattage resistors, diodes, and caps have to be added.
There is a pair of 10,000 ufd caps and diode bridge for each LM3886 in the fuill version. The base version only has a single LM3886 per channel, and 40K ufd, and two diode bridges.
BTW, I will start a new thread when posting the pics, even though it is still the ip of Mauro, it is a little more commercial. He is not giving out the files to make circuit boards this time around..
OT, Troy, I was in Layette Friday. Hope the tornados in New Iberia missed you and yours.
George
The front is in the lower picture, that is a 16 x 16 parmetal case. The black thing on the bottom of the stack.
The inside is nothing to brag about, Mauro sells the boards with most components already soldered in. The components he uses are all surface mount. It has regs to feed the LM318 this time. All the higher wattage resistors, diodes, and caps have to be added.
There is a pair of 10,000 ufd caps and diode bridge for each LM3886 in the fuill version. The base version only has a single LM3886 per channel, and 40K ufd, and two diode bridges.
BTW, I will start a new thread when posting the pics, even though it is still the ip of Mauro, it is a little more commercial. He is not giving out the files to make circuit boards this time around..
OT, Troy, I was in Layette Friday. Hope the tornados in New Iberia missed you and yours.
George
Hi,
i`m very curious about this unusual amplifier design. Especially all the compensation capacitors puzzled me a little. Of course there needed, but I wonder about the impact on amplifier speed.
Are there any slewrate and bandwith figures available?
Sorry, i didn´t read all the 268 pages in this thread.
😱
Regards
Juergen
i`m very curious about this unusual amplifier design. Especially all the compensation capacitors puzzled me a little. Of course there needed, but I wonder about the impact on amplifier speed.
Are there any slewrate and bandwith figures available?
Sorry, i didn´t read all the 268 pages in this thread.
😱
Regards
Juergen
Has anyone used Jensen 4 pole caps in the MyRef RevC? I'm
using them in a Dac AH and CD player with excellent results. I'm
just not sure where in the circuit to place them. Would putting
one right after the rectifier, before C3 and C8 be OK? Here's their
white paper. I can't say enough good about these.
They're pricey, but worth every penny.
http://www.jensencapacitors.com/audio/white-papers/4pole.html
Thanks-Marty in Sacramento
using them in a Dac AH and CD player with excellent results. I'm
just not sure where in the circuit to place them. Would putting
one right after the rectifier, before C3 and C8 be OK? Here's their
white paper. I can't say enough good about these.
They're pricey, but worth every penny.
http://www.jensencapacitors.com/audio/white-papers/4pole.html
Thanks-Marty in Sacramento
Will work fine
I use them in several of my projects also. None of the MP designs though.
I think you will be very happy with the 10,000 ufd, 50 volt Panasonics. The Jensens might offer a slight improvement in resisdual noise. I am not sure if it would be audible.
Also due to the low impedance, I have needed to install sub ohm value resistors in series between the Jensens and diodes. This was another power amp. The noise was way too large without. I have never needed this bandaid was the cheap Panasonics. Yhis is mentioned in either the Jensen or DNM paers on these caps.
My advice is to try them, pay attention to how Mauro wired the My_Ref, and be ready to add say 0.2 ohm resistors after the rectifiers.
George
I use them in several of my projects also. None of the MP designs though.
I think you will be very happy with the 10,000 ufd, 50 volt Panasonics. The Jensens might offer a slight improvement in resisdual noise. I am not sure if it would be audible.
Also due to the low impedance, I have needed to install sub ohm value resistors in series between the Jensens and diodes. This was another power amp. The noise was way too large without. I have never needed this bandaid was the cheap Panasonics. Yhis is mentioned in either the Jensen or DNM paers on these caps.
My advice is to try them, pay attention to how Mauro wired the My_Ref, and be ready to add say 0.2 ohm resistors after the rectifiers.
George
Panel, that's good advice. The amp already smokes my
Williamsons, so I
may forgo using them after all.
Marty
Williamsons, so I
may forgo using them after all.
Marty
Cheaper idea
This is a tweak implimented recently that in two of my MP amps. I added a couple small value, low ESR caps close to the power pins of the LM3886.
One amp had 1000 ufd caps after the main filter caps, here 22 ufd caps were used to go from rails to ground. The other had the recommended 220 ufd caps and here 4.7 ufd caps were used.
In both instances the ratio was about 50:1, as far as cap size. This ratio was just a guess. ALso, none were soldered directly to the pins. A short trace seperated them from the chips.
The sonic benefit was better slam. Maybe a little quieter, but not huge. The bottom end seems a little stronger also. The lowend may be just better slam.
My guess here is that the small value, low ESR caps have less inductance than the larger caps closer to the diodes. And the greatly reduced track length is a factor.
Being further from the diodes seems to help in diode noise also. Placing low ESR caps close to the diodes usually increases the grundge generated.
With a dollars worth of Panasonic FC or FM caps, the results may be what you hope to get from the 4 poles. At least in an amplifier. I still use them in my linestage and phono and am very happy.
George
This is a tweak implimented recently that in two of my MP amps. I added a couple small value, low ESR caps close to the power pins of the LM3886.
One amp had 1000 ufd caps after the main filter caps, here 22 ufd caps were used to go from rails to ground. The other had the recommended 220 ufd caps and here 4.7 ufd caps were used.
In both instances the ratio was about 50:1, as far as cap size. This ratio was just a guess. ALso, none were soldered directly to the pins. A short trace seperated them from the chips.
The sonic benefit was better slam. Maybe a little quieter, but not huge. The bottom end seems a little stronger also. The lowend may be just better slam.
My guess here is that the small value, low ESR caps have less inductance than the larger caps closer to the diodes. And the greatly reduced track length is a factor.
Being further from the diodes seems to help in diode noise also. Placing low ESR caps close to the diodes usually increases the grundge generated.
With a dollars worth of Panasonic FC or FM caps, the results may be what you hope to get from the 4 poles. At least in an amplifier. I still use them in my linestage and phono and am very happy.
George
seperate PSU for LM318 ?
Does it make sense to throw out the noisy zeners and add a seperate regulated psu for the LM318? If so, would it be better to use a seperate transformer or get the voltage from the main caps?
Maybe this was asked before somewhere in this monster thread, but whoever could find ...
Does it make sense to throw out the noisy zeners and add a seperate regulated psu for the LM318? If so, would it be better to use a seperate transformer or get the voltage from the main caps?
Maybe this was asked before somewhere in this monster thread, but whoever could find ...
Hi Iván,
it's better to refer to post numbers (like Post #2692), the page numbers depend on user settings - i.e. for me this thread has 54 pages.
best, LC
it's better to refer to post numbers (like Post #2692), the page numbers depend on user settings - i.e. for me this thread has 54 pages.
best, LC
Modular approach
I have been tinkering with my own current pump amps and have been hankering for the same things many others have.
1) Make the whole thing more modular.
2) Allow for distinct supplies separate from amp PCB.
3) Allow for alternate pump designs even discrete allowing for much more power.
4) Symmetrical operation with bridged outputs which will load the power supplies symmetrically and has huge benefits to SNR and Distortion.
5) Separate speaker protection that is more universal, and can be omitted if one chooses.
I have all of this in the works and most of it tested and working.
Currently, One can easily remove the zeners and load resistors in my "RevC" PCB and use a good low current PS like my "LCPS" which utilized two LM317s(or compatible) to provide a split supply. To do this you would use an additional transformer, or you could simply wind yourself a couple additional secondaries if you have a toroidal transformer. In this case the good decoupling around the LM318 means that the low voltage supply does not have to be terribly close. A few inches of wire will not cause any problem. You could easily place the LCPS in front of the RevC PCB.
One other option, we also have a high current supply that we use for our TXO amps etc... You could easily omit the bridge on the revC board and utilize that power supply. It already has a simpler source follower MOSFET based regulated output which is a bit quieter and lower output impedance than the straight zener approach. It also could be used a pre-regulator into something else allowing you to use a single large toroid without bothering with additional windings. It also has spots for larger (35mm) caps and is intended to use the very good monolithic bridges from International Rectifier and others, you can also use a simple rectifier PCB if you would like MURs or something. I can post the PDFs for the bridge board if you like.
The PSRR of the LM3886 in general and the MyRef in specific is VERY good. In fact, when I took my amp to the local university a year or so ago to show my friends in the physics lab, we did some quick testing and the ripple rejection was very impressive. In all respects the amp actually measured better in those tests then Mauro claims in his design documentation. So Mauro was being very conservative in his statements. I have always hoped to get the amplifier measured more thoroughly, and hopefully I will have the means to do so someday.
Anyway, I have made a lot of progress with my own transconductance amps, and I will post more later, but probably in its own thread, because my new work substantially differs from what Mauro graciously did for us here.
Cheers!
Russ
Cheers!
Russ
I have been tinkering with my own current pump amps and have been hankering for the same things many others have.
1) Make the whole thing more modular.
2) Allow for distinct supplies separate from amp PCB.
3) Allow for alternate pump designs even discrete allowing for much more power.
4) Symmetrical operation with bridged outputs which will load the power supplies symmetrically and has huge benefits to SNR and Distortion.
5) Separate speaker protection that is more universal, and can be omitted if one chooses.
I have all of this in the works and most of it tested and working.
Currently, One can easily remove the zeners and load resistors in my "RevC" PCB and use a good low current PS like my "LCPS" which utilized two LM317s(or compatible) to provide a split supply. To do this you would use an additional transformer, or you could simply wind yourself a couple additional secondaries if you have a toroidal transformer. In this case the good decoupling around the LM318 means that the low voltage supply does not have to be terribly close. A few inches of wire will not cause any problem. You could easily place the LCPS in front of the RevC PCB.
One other option, we also have a high current supply that we use for our TXO amps etc... You could easily omit the bridge on the revC board and utilize that power supply. It already has a simpler source follower MOSFET based regulated output which is a bit quieter and lower output impedance than the straight zener approach. It also could be used a pre-regulator into something else allowing you to use a single large toroid without bothering with additional windings. It also has spots for larger (35mm) caps and is intended to use the very good monolithic bridges from International Rectifier and others, you can also use a simple rectifier PCB if you would like MURs or something. I can post the PDFs for the bridge board if you like.
The PSRR of the LM3886 in general and the MyRef in specific is VERY good. In fact, when I took my amp to the local university a year or so ago to show my friends in the physics lab, we did some quick testing and the ripple rejection was very impressive. In all respects the amp actually measured better in those tests then Mauro claims in his design documentation. So Mauro was being very conservative in his statements. I have always hoped to get the amplifier measured more thoroughly, and hopefully I will have the means to do so someday.
Anyway, I have made a lot of progress with my own transconductance amps, and I will post more later, but probably in its own thread, because my new work substantially differs from what Mauro graciously did for us here.
Cheers!
Russ
Cheers!
Russ
Low noise Supply for LM318
I´ve just etched the boards for this psu: http://www.readresearch.co.uk/mains_op-amp_psu/mains_op-amp_psu.htm Nice layout, I think.
Guess I´ll be ready by weekend and will post my findings and listening impressions then.
I´ve just etched the boards for this psu: http://www.readresearch.co.uk/mains_op-amp_psu/mains_op-amp_psu.htm Nice layout, I think.
Guess I´ll be ready by weekend and will post my findings and listening impressions then.
Hi
I've made pcb FOR LM 4780 paralel current pump, but I'm not tried it yet. Please comment my design and PCB layout.
NB : I don't know how to attach my drawing directly for ease comment. Do I shall convert all my file to pdf? Please help me
thanks in advance
Lukio
😀
I've made pcb FOR LM 4780 paralel current pump, but I'm not tried it yet. Please comment my design and PCB layout.
NB : I don't know how to attach my drawing directly for ease comment. Do I shall convert all my file to pdf? Please help me
thanks in advance
Lukio
😀