GND in amp case which is + on the 22 mF filter cap in the LC filter is connected to chassis via the usual 10 ohm NTC.
The power cable from PSU chassis will have the yellow/green wire which is also connected to the PSU chassis.
Will see where I can find some shielded power cable. Then connect yellow/green wire to shield at amp end........then I need to mark which connector should go to amp. Connectors are 4 pole Neutrik SpeakOn.
The power cable from PSU chassis will have the yellow/green wire which is also connected to the PSU chassis.
Will see where I can find some shielded power cable. Then connect yellow/green wire to shield at amp end........then I need to mark which connector should go to amp. Connectors are 4 pole Neutrik SpeakOn.
no need for coax cable all the way, speaking of amp itself
if anything, just shield it inside amp case
old VGA cables are having great shield inside - find one, skin it, voila!
if anything, just shield it inside amp case
old VGA cables are having great shield inside - find one, skin it, voila!
Ok, I could let the 4th terminal in SpeakOn connector be the shield and then connect it in amp case.
To get access to the 4th terminal in chassis mount SpeakOn connector (which is the bottom one terminal) needs a bit of disconnects of wires 🙂 ......but it is doable of course.....in stead of making the connection in cable connector (shield to yellow/green).
I wonder if I have trashed my VGA cables.....or they are hidden somewhere 🙂 ...then the trick is to parallel wires I guess.....to get enough "mm2".....
To get access to the 4th terminal in chassis mount SpeakOn connector (which is the bottom one terminal) needs a bit of disconnects of wires 🙂 ......but it is doable of course.....in stead of making the connection in cable connector (shield to yellow/green).
I wonder if I have trashed my VGA cables.....or they are hidden somewhere 🙂 ...then the trick is to parallel wires I guess.....to get enough "mm2".....
if amp case is on safety gnd, connect shield to it
always go with simplest wiring which covers all your needs
always go with simplest wiring which covers all your needs
Yes, amp case is connected to safety gnd via the DC power cable where safety gnd is one of the wires. This wire is connected via AC mains yellow/green in PSU case.
I ordered 2 x 1m of this cable: SUPRA LoRad MKII 3x1.5 mm² to be used as DC power cable.
When I had the amps playing shortly I connected directly to DAC in pre-amp mode (= active digital vol control). With max. 2Vpp out normal listening level was full output (more or less depending on recording level).
I also have XLR out which has 4Vpp max. out. Then I also ordered two of these adapters (female XLR to female RCA):
Neutrik NA2FPMF (https://www.neutrik.com/en/product/na2fpmf).
I guess this should give me 4Vpp at RCA (at adapter) if V- is used as reference. If not it is just bad luck 🙂
Then I can use this configuration until I get a balanced Iron pre kit.
My DAC has male chassis mount XLR-out. I find this a bit strange as it would be more logical to use female XLR out. Then less chance to short the output by mistake. It was good I checked else I would have ordered the wrong adapter. Strange world.......
I ordered 2 x 1m of this cable: SUPRA LoRad MKII 3x1.5 mm² to be used as DC power cable.
When I had the amps playing shortly I connected directly to DAC in pre-amp mode (= active digital vol control). With max. 2Vpp out normal listening level was full output (more or less depending on recording level).
I also have XLR out which has 4Vpp max. out. Then I also ordered two of these adapters (female XLR to female RCA):
Neutrik NA2FPMF (https://www.neutrik.com/en/product/na2fpmf).
I guess this should give me 4Vpp at RCA (at adapter) if V- is used as reference. If not it is just bad luck 🙂
Then I can use this configuration until I get a balanced Iron pre kit.
My DAC has male chassis mount XLR-out. I find this a bit strange as it would be more logical to use female XLR out. Then less chance to short the output by mistake. It was good I checked else I would have ordered the wrong adapter. Strange world.......
2m screened cable arrived which I cut into two pieces (I need two DC-cables). It was so fun to cut. Difficult not to continue to cut into smaller pieces. It was "like butter" with my cable cutter. Plan to mount Neutrik connectors during the weekend......
I wonder if the arrows printed on cable indicates a "direction"? ......crazy world if that is true......
I wonder if the arrows printed on cable indicates a "direction"? ......crazy world if that is true......
Attachments
Some final adjustments with external SMPS PSU and LC filter in amp case.
After closed cover I made a quick REW measurement on one channel to check how it looks.
My measurement setup is not that good for power amp measurement especially not when amp has no voltage gain. So it was just to check that I had no bigger problem. I use a small Atika 1000 Hz generator. With this I could get 2.31 V RMS over 6R8 resistor. It is about 0.8 W out.
If other channel shows same behavior I will start thinking how to reorganize my system (two mono blocks + two PSU boxes) with all the connecting wires etc.
As far as I can see I can expect a silent setup.
After closed cover I made a quick REW measurement on one channel to check how it looks.
My measurement setup is not that good for power amp measurement especially not when amp has no voltage gain. So it was just to check that I had no bigger problem. I use a small Atika 1000 Hz generator. With this I could get 2.31 V RMS over 6R8 resistor. It is about 0.8 W out.
If other channel shows same behavior I will start thinking how to reorganize my system (two mono blocks + two PSU boxes) with all the connecting wires etc.
As far as I can see I can expect a silent setup.
Attachments
Wooohaa! 🙂👍
You will have to do extended listening tests, and then get back to us with your findings and opinion. 🎷🙂🎸
You will have to do extended listening tests, and then get back to us with your findings and opinion. 🎷🙂🎸
Yes, the plan is to add Iron Pre later if I am able to get a balanced kit and then built it as a linestage (without vol control and relays).
Before that the plan is to use a XLR to RCA adapter from DAC and directly into the Lazy Bush. In both cases I will use the DAC as preamp. It works very well with VFET kit amp. I learned from watching a PS-Audio video that using a resistive element as vol control is something you did 50 years back or so 🙂
Before that the plan is to use a XLR to RCA adapter from DAC and directly into the Lazy Bush. In both cases I will use the DAC as preamp. It works very well with VFET kit amp. I learned from watching a PS-Audio video that using a resistive element as vol control is something you did 50 years back or so 🙂
The numbers, both distortion and noise, in the upper left corner do not resemble what is shown graphically. Something is wrong with that output.
I was looking just on graph and scales, not numbers
I mean - I was expecting them to look exactly as that, so didn't go further
I mean - I was expecting them to look exactly as that, so didn't go further
Yes, I don't know why it shows 100% noise figures in the box. I switched from internal to external generator (to have larger signal). Maybe REW still "think" the internal generator is running and measures on that (in the window). Normally when no signal the noise is like 100%.
I am quite sure the graph is correct. The speakers are totally "dead" regarding noise / hum.
What I do hear is a faint mechanical "buzz" from the transformers in the SMPS's when no music is playing. I will try to cure that using bitumen in lid or isolate the SMPS's.
I am quite sure the graph is correct. The speakers are totally "dead" regarding noise / hum.
What I do hear is a faint mechanical "buzz" from the transformers in the SMPS's when no music is playing. I will try to cure that using bitumen in lid or isolate the SMPS's.
I will write about first listening experience when I am back home.
The immediate first observation was a fantastic "transparency". Speakers just stood in the room as "dead elephants".
The immediate first observation was a fantastic "transparency". Speakers just stood in the room as "dead elephants".
I bit more feedback regarding the sound now I have made the amp silent!
Before I played the VFET kit amp just connected to my DAC. VFET kit amp has some voltage gain. For Lazy Bush I used the balanced output of DAC using a XLR to RCA converter. It gives me almost the gain I need. Think it will be just perfect to get the Iron Pre to have a bit more "overhead".
"Lazy Bush" does everything VFET kit amp does. Maybe even more precise stereo imaging and depth. I have not heard better stereo imaging than this one. Maybe speaker placement does the most but amp has also something to say.
Voices are very natural. Diana Krall "Live from Paris" is a nice example of excellent stereo imaging. Good control in bas area also. Deep powerful bas response.
Overall very "polished" and never "hard" sound. It still plays high tones. 10 KHz and 16 KHz from test stereo CD 🙂 20 KHz I can't hear anymore.......but amp can play it I am sure.
This recording of Beethovens 5th is very sensitive. Quite low recorded but with a lot of details and with a not so good amp this gets into a "mess". But excellent job by Lazy Bush (recording is available from Tidal).
http://www.teodor-currentzis.com/index.php/discography/beethoven-symphony-no-5/
I wonder what Iron Pre will do to the sound. I don't need more "polished". Maybe the extra "overhead" makes the Iron Pre a nice contribution. Time will tell.....
On 2nd image I put a bitumen sheet over the two SMPS cases to check if this could solve the faint mechanical buzz from the SMPS transformers and also to check how hot its get when ventilation holes on top is covered. It seems like a fine solution. So next project will be to dampen the chassis with bitumen inside.
Later the SMPS cases will go on middel shelf (on top of the PS-Audio regenerator) and streamer + DAC + "future" Iron Pre will go on the top.
I still need more listening time.......
It gets quite hot in the living room with the extra 400W of heat. Maybe Lazy Bush as Winter-amp and VFET as Summer-amp 🙂
VFET kit amp is running cool compared to these "Lazy" mono blocks! .....I can keep my fingers 2 sec where it is hottest after 2-3 hours of burning. I think this is ok. +5 C during the summer will probably be OK also. I will do a measurement during a hot summer day.
Before I played the VFET kit amp just connected to my DAC. VFET kit amp has some voltage gain. For Lazy Bush I used the balanced output of DAC using a XLR to RCA converter. It gives me almost the gain I need. Think it will be just perfect to get the Iron Pre to have a bit more "overhead".
"Lazy Bush" does everything VFET kit amp does. Maybe even more precise stereo imaging and depth. I have not heard better stereo imaging than this one. Maybe speaker placement does the most but amp has also something to say.
Voices are very natural. Diana Krall "Live from Paris" is a nice example of excellent stereo imaging. Good control in bas area also. Deep powerful bas response.
Overall very "polished" and never "hard" sound. It still plays high tones. 10 KHz and 16 KHz from test stereo CD 🙂 20 KHz I can't hear anymore.......but amp can play it I am sure.
This recording of Beethovens 5th is very sensitive. Quite low recorded but with a lot of details and with a not so good amp this gets into a "mess". But excellent job by Lazy Bush (recording is available from Tidal).
http://www.teodor-currentzis.com/index.php/discography/beethoven-symphony-no-5/
I wonder what Iron Pre will do to the sound. I don't need more "polished". Maybe the extra "overhead" makes the Iron Pre a nice contribution. Time will tell.....
On 2nd image I put a bitumen sheet over the two SMPS cases to check if this could solve the faint mechanical buzz from the SMPS transformers and also to check how hot its get when ventilation holes on top is covered. It seems like a fine solution. So next project will be to dampen the chassis with bitumen inside.
Later the SMPS cases will go on middel shelf (on top of the PS-Audio regenerator) and streamer + DAC + "future" Iron Pre will go on the top.
I still need more listening time.......
It gets quite hot in the living room with the extra 400W of heat. Maybe Lazy Bush as Winter-amp and VFET as Summer-amp 🙂
VFET kit amp is running cool compared to these "Lazy" mono blocks! .....I can keep my fingers 2 sec where it is hottest after 2-3 hours of burning. I think this is ok. +5 C during the summer will probably be OK also. I will do a measurement during a hot summer day.
