First test with adjustable DC power supplies set to 17,5V was very successful. Matching of the semiconductors paid off [emoji106]
Both channels run at 120mA (R10=12R) and both J3 are conducting at 5,6mA (R3=240R).
First listening test with a simple Koss PortaPro gave a clean sound. So next task is to build the final PS and case...
Thanks Salas for the nice Pre/HPA.
That's the correct way to approach case/chassis selection.
Get it working first, then see how bg the assembly is that needs to fit inside the enclosure.
Remember to fold up the finalised electronics to the shape needed to fit and see if performance changes, before ordering/designing the enclosure.
Get it working first, then see how bg the assembly is that needs to fit inside the enclosure.
Remember to fold up the finalised electronics to the shape needed to fit and see if performance changes, before ordering/designing the enclosure.
First test with adjustable DC power supplies set to 17,5V was very successful. Matching of the semiconductors paid off [emoji106]
Both channels run at 120mA (R10=12R) and both J3 are conducting at 5,6mA (R3=240R).
First listening test with a simple Koss PortaPro gave a clean sound. So next task is to build the final PS and case...
Thanks Salas for the nice Pre/HPA.
Congrats.
A design detail is that the recommended bias range resides at the zero tempco area of the IRF9610s. Combined with a CCS (M3) and adequate sinking, the bias current draw is usually measuring very steady from cold to hot and during the rest of operation also. By checking R10s drop periodically is the simplest way to confirm that as an additional all is OK test.
Time to summarize my DCG3 build and to share with you about first SQ results include a brief review of Monolith M1060 Rev2. So, I decided to go for x3 gain and to set current to 150mA. Gain decision was made based on my F5T measurements and you can see my final results here (#53): http://www.diyaudio.com/forums/pass-labs/304826-f5t-gain-structure-preamp-choice-6.html
Still need to add i-Select, female RCAs and to drill front panel for volume and input selector knobs.
My measurements:
1. Vin (DC) = +/- 17.23v for all DC inputs (after Rx and Ry tuning)
2. R10 (7R5) current is 161mA and 164mA.
3. OFFSET: it is fluctuating from -0.00100V up to +0.00150V
4. Heatsink temperature after 1 hour run time: 34 deg C (it is about 10 deg C above ambient)
I use oversized thick aluminum enclosure from eBay and BOT panel is 4mm thick: WA52 Full Aluminum amplifier Enclosure/mini AMP case/ Preamp box/ PSU chassis | eBay
Cupper bar is also from eBay: 3/8"x 1-1/2" C110 COPPER BAR 12" long Solid Flat Bar .375" Bus Bar Stock H02 | eBay
My cupper bar is connected to the BOT tightly and I use heatsink compound there too. So, my heat dissipation is very effective with such big mass. I been advised and I decided to use 25kOhm Goldpoit 48 steps attenuator for volume control and Mogami 2330 coax for all inputs.
Use twisted pair (Teflon, silver plated mil spec 18AWG) for outputs by now, but might go for some thicker than 2330 coax for the final.
This is not my first Salas piece of art and not the first amazing kit from Tea Bag, then the instructions are amazingly simple and easy to understand. The whole assembly and setup was very enjoyable process.
SQ test made with Wilson Benesch TT with AT-ART9 cart and Salas FSP (MC phono), NAD M5 CD player, F5T monoblocks amps and Acoustic Zen Adagio speakers, Acoustic Zen Silver interconnects and same brand Hologram II speaker cables.
It is … amazing. I used Tube preamp (before I made DCG3) and it is day and night changes. More air, more details. My bass was very weak without Sub and too pronounced with it even set to min gain on it. Now I have correct mid and low bass. All instruments sound like they should. Very natural for classic music and old Jazz. I also tested my new purchase ¬ - Monolith M1060 Rev2 (with fixes found on Rev1). What I can say. It is the best headphones and headphone amp that I ever tried. I thought that my AKG K701 is nice, but you should listen to these Monoprice headphones.
I’m very happy man!
I’ll send new images when all will be finalized, drilled, installed and sent to my stereo rack.
Still need to add i-Select, female RCAs and to drill front panel for volume and input selector knobs.
My measurements:
1. Vin (DC) = +/- 17.23v for all DC inputs (after Rx and Ry tuning)
2. R10 (7R5) current is 161mA and 164mA.
3. OFFSET: it is fluctuating from -0.00100V up to +0.00150V
4. Heatsink temperature after 1 hour run time: 34 deg C (it is about 10 deg C above ambient)
I use oversized thick aluminum enclosure from eBay and BOT panel is 4mm thick: WA52 Full Aluminum amplifier Enclosure/mini AMP case/ Preamp box/ PSU chassis | eBay
Cupper bar is also from eBay: 3/8"x 1-1/2" C110 COPPER BAR 12" long Solid Flat Bar .375" Bus Bar Stock H02 | eBay
My cupper bar is connected to the BOT tightly and I use heatsink compound there too. So, my heat dissipation is very effective with such big mass. I been advised and I decided to use 25kOhm Goldpoit 48 steps attenuator for volume control and Mogami 2330 coax for all inputs.
Use twisted pair (Teflon, silver plated mil spec 18AWG) for outputs by now, but might go for some thicker than 2330 coax for the final.
This is not my first Salas piece of art and not the first amazing kit from Tea Bag, then the instructions are amazingly simple and easy to understand. The whole assembly and setup was very enjoyable process.
SQ test made with Wilson Benesch TT with AT-ART9 cart and Salas FSP (MC phono), NAD M5 CD player, F5T monoblocks amps and Acoustic Zen Adagio speakers, Acoustic Zen Silver interconnects and same brand Hologram II speaker cables.
It is … amazing. I used Tube preamp (before I made DCG3) and it is day and night changes. More air, more details. My bass was very weak without Sub and too pronounced with it even set to min gain on it. Now I have correct mid and low bass. All instruments sound like they should. Very natural for classic music and old Jazz. I also tested my new purchase ¬ - Monolith M1060 Rev2 (with fixes found on Rev1). What I can say. It is the best headphones and headphone amp that I ever tried. I thought that my AKG K701 is nice, but you should listen to these Monoprice headphones.
I’m very happy man!
I’ll send new images when all will be finalized, drilled, installed and sent to my stereo rack.
Attachments
Alex, congrats. Very nice work in progress indeed. The chunky R-Core trafo and the high quality switcher pot are also plus points in your build.
The second transformer (small toroid) is anticipating the In-Selector board in self powered own PSU mode I would guess. Remember that the selector board's PSU 0 must have same reference as the rest of the boards so to avoid hum.
Because when on its own transformer the DC power return on that board is isolated from the rest of the boards. Some builders forgo a second Tx and just tap AC for it from a main transformer (the midpoint and a ~ at one DCSTB's AC in connector) when using I-Select's own PSU. Others don't populate its own small PSU section and tap raw DC or regulated DC from one DCSTB for it. Either to hack the selector board shorter for fitting it in a small space or just because its handy to power it so. In both cases all the DC power line zeroes are already together.
Nice with the Rev2 M1060 Monoliths. I hope your 3X gain choice is enough for high SPL from them also. A quick look in sensitivity and mW numbers tell me it should. I haven't seen a Rev2's picture yet. Have you got one? Especially on how the new headpiece connectors and new cable look like.
BTW which one is your tube preamp?
The second transformer (small toroid) is anticipating the In-Selector board in self powered own PSU mode I would guess. Remember that the selector board's PSU 0 must have same reference as the rest of the boards so to avoid hum.
Because when on its own transformer the DC power return on that board is isolated from the rest of the boards. Some builders forgo a second Tx and just tap AC for it from a main transformer (the midpoint and a ~ at one DCSTB's AC in connector) when using I-Select's own PSU. Others don't populate its own small PSU section and tap raw DC or regulated DC from one DCSTB for it. Either to hack the selector board shorter for fitting it in a small space or just because its handy to power it so. In both cases all the DC power line zeroes are already together.
Nice with the Rev2 M1060 Monoliths. I hope your 3X gain choice is enough for high SPL from them also. A quick look in sensitivity and mW numbers tell me it should. I haven't seen a Rev2's picture yet. Have you got one? Especially on how the new headpiece connectors and new cable look like.
BTW which one is your tube preamp?
Thank you, Salas. That chunky R-Core is 120VA 4x18V made in India and I got it by luck from Selectronic. It was a replacement unit for the damaged during shipment one that I ordered about a year ago . Was not easy to figure out its wiring, but I use Mark Jonhson's trany polarity tester and the whole process was simplified. If someone interested, it is here: http://www.diyaudio.com/forums/powe...rmer-phasedots-no-scope-signal-generator.html
In did, my second trany (toroid) is intend to feed i-Select and I plan to go for the same GND elevation as I used for DCSTB channels with two of these units: House GND Kit
I did not use 1R resistors to separate 2 mono channels and just used two units. Not cheap, but better aesthetically looking than SS rectifier bock. It is question of taste…
I got Rev2 of Monolith headphones and Monoprice fixed the most of things that people complied about. Please see attached images. Cable is 6FT now and 2,5mm connectors instead of MMCX. I assume they use some type of electropolish with anisotropy etch to fix sharpness of girls. More material removed from edges and less at the thick portion of these bars. It is very smooth now. Some guy already made a video about Rev2: https://www.youtube.com/watch?v=YE3Zu6vjZzU
My tube preamp is Triode TRV-4SE Special Edition. It is upgraded with new output CAPs (Vcap) and Step Attenuator volume control.Probably, will sale it soon.
In did, my second trany (toroid) is intend to feed i-Select and I plan to go for the same GND elevation as I used for DCSTB channels with two of these units: House GND Kit
I did not use 1R resistors to separate 2 mono channels and just used two units. Not cheap, but better aesthetically looking than SS rectifier bock. It is question of taste…
I got Rev2 of Monolith headphones and Monoprice fixed the most of things that people complied about. Please see attached images. Cable is 6FT now and 2,5mm connectors instead of MMCX. I assume they use some type of electropolish with anisotropy etch to fix sharpness of girls. More material removed from edges and less at the thick portion of these bars. It is very smooth now. Some guy already made a video about Rev2: https://www.youtube.com/watch?v=YE3Zu6vjZzU
My tube preamp is Triode TRV-4SE Special Edition. It is upgraded with new output CAPs (Vcap) and Step Attenuator volume control.Probably, will sale it soon.
Attachments
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