Hi all
Finally starting to put my Aksa Lender together. I missed a couple of things on my parts order so hopefully they will arrive eventually and I can finish it up. In the mean time I was reading my notes on the build and it reminded me of post number 1035. Very slightly off topic but I can't wait to hear this through the AKSA. I would like to thank Maty Tinman for bringing Ahmad Jamal's album "Ahmad's Blues" to my attention last year, something I never would have heard otherwise. It certainly has many elements that make it a very good listen. Whilst I'm not a particular fan of Jazz I have enjoyed it live many many times, mainly for the live sound and the atmosphere in some clubs/bars. It really is a good listen whether you like Jazz or not.
Finally starting to put my Aksa Lender together. I missed a couple of things on my parts order so hopefully they will arrive eventually and I can finish it up. In the mean time I was reading my notes on the build and it reminded me of post number 1035. Very slightly off topic but I can't wait to hear this through the AKSA. I would like to thank Maty Tinman for bringing Ahmad Jamal's album "Ahmad's Blues" to my attention last year, something I never would have heard otherwise. It certainly has many elements that make it a very good listen. Whilst I'm not a particular fan of Jazz I have enjoyed it live many many times, mainly for the live sound and the atmosphere in some clubs/bars. It really is a good listen whether you like Jazz or not.
Progress
Hi all
Progress picture, which has hopefully attached, and a question or two. I will be separating the boards but have just kept them together while I'm working.
I am just waiting on a couple of pieces to finish the pre-amp up such as R10 and R11, originally I had 10k and 1k but have since decided to order 33k and 6k8 after reading a post from XRK earlier in the thread. All that's left is arrival of a chassis and some time to finish it. However, I have also ordered the incorrect toroidal inductor from Mouser 2300HT-220-V-RC. The datasheet link:
https://nz.mouser.com/datasheet/2/54/2300ht_series-776374.pdf
The correct part from Farnell is a Wurth 744017. The datasheet link:
http://www.farnell.com/datasheets/2...38.822102680.1586235817-2104837401.1585897469
Apart from the fact I would have to mount the inductor off the board, as its physically a bit larger, the DC Resistance Max is 0.008R compared to the Wurth 0.015R Max and higher current rating would the 2300HT from Mouser be useable?
Thanks in advance
Hi all
Progress picture, which has hopefully attached, and a question or two. I will be separating the boards but have just kept them together while I'm working.
I am just waiting on a couple of pieces to finish the pre-amp up such as R10 and R11, originally I had 10k and 1k but have since decided to order 33k and 6k8 after reading a post from XRK earlier in the thread. All that's left is arrival of a chassis and some time to finish it. However, I have also ordered the incorrect toroidal inductor from Mouser 2300HT-220-V-RC. The datasheet link:
https://nz.mouser.com/datasheet/2/54/2300ht_series-776374.pdf
The correct part from Farnell is a Wurth 744017. The datasheet link:
http://www.farnell.com/datasheets/2...38.822102680.1586235817-2104837401.1585897469
Apart from the fact I would have to mount the inductor off the board, as its physically a bit larger, the DC Resistance Max is 0.008R compared to the Wurth 0.015R Max and higher current rating would the 2300HT from Mouser be useable?
Thanks in advance
Attachments
Just bought the TKD potentiometer for it. I had bought a cheap potentiometer for testing purposes but will be installing the TKD shortly.
X,
Do you have a specific grounding scheme for this preamp? On my preamp I'm totally fine but the one from my friend has this giga hum... He's got a set of MoFo monoblocks that when connected create a huge loud hum. If he only connect a single channel at a time it is totally fine and when using just headphones it is fine. The power for the AKSA is SMPS brick. It is not in a final chassis yet, I don't believe so. Just if you have ideas to try out. On my AKSA Lender I'm using a Sigma 22 (just - and + and leaving the ground floating) and it is totally silent. I know sometimes SMPS will cause noise like this. The MoFo's are also using SMPS bricks.
All the best!
Do
X,
Do you have a specific grounding scheme for this preamp? On my preamp I'm totally fine but the one from my friend has this giga hum... He's got a set of MoFo monoblocks that when connected create a huge loud hum. If he only connect a single channel at a time it is totally fine and when using just headphones it is fine. The power for the AKSA is SMPS brick. It is not in a final chassis yet, I don't believe so. Just if you have ideas to try out. On my AKSA Lender I'm using a Sigma 22 (just - and + and leaving the ground floating) and it is totally silent. I know sometimes SMPS will cause noise like this. The MoFo's are also using SMPS bricks.
All the best!
Do
Got the chassis and now waiting on volume knob, potentiometer and source selector extension and RCA jacks. 3 weeks of waiting already. Everything is so slow these days!
Do
Potentiometer possibilities
Now that my MoFo amp(s) are back in service
, I'm getting my parts list for this preamplifier in order.
As such, I have a few questions about potentiometers:
Now that my MoFo amp(s) are back in service
, I'm getting my parts list for this preamplifier in order.As such, I have a few questions about potentiometers:
- Is there really a compelling 20x quality reason to justify using the TKD potentiometer instead of the ALPS? Are they not both carbon-based?
- Among the list of potentiometer types is "carbon", "cermet", "plastic", and "metal". The reasons I have seen involve heat dissipation, but given the application, that shouldn't be an issue. I'm more interested in sound quality and reliability, especially since this application has the potentiometer 'in the path'. "Plastic" is recommended for 'smoothness'. Why choose one type or the other?
- Is there some known failure or quality problem with the "old style" big, round, perfboard-type potentiometers? Something like Bourns PDB18 series.
- Resistance taper profiles. Oy vey. Audio? Linear? What? 'Linear' vs. 'Swoosh' vs 'Zener' profiles? School me.
Now that my MoFo amp(s) are back in service
As such, I have a few questions about potentiometers:
- Is there really a compelling 20x quality reason to justify using the TKD potentiometer instead of the ALPS? Are they not both carbon-based?
- Among the list of potentiometer types is "carbon", "cermet", "plastic", and "metal". The reasons I have seen involve heat dissipation, but given the application, that shouldn't be an issue. I'm more interested in sound quality and reliability, especially since this application has the potentiometer 'in the path'. "Plastic" is recommended for 'smoothness'. Why choose one type or the other?
- Is there some known failure or quality problem with the "old style" big, round, perfboard-type potentiometers? Something like Bourns PDB18 series.
- Resistance taper profiles. Oy vey. Audio? Linear? What? 'Linear' vs. 'Swoosh' vs 'Zener' profiles? School me.
Hi dliscomb,
Let's not get in the debate of conductive plastic sounds "smooth" as this is very subjective and in reality, if you put your mind into thinking something sounds a certain way, you might end up hearing it this way.
The TKD offers way better tracking than the cheap 3$ pot and I know because I've tested many times the scenario. They use conductive plastic which shouldn't rendering differently soundwise if another type of potentiometer is well designed. Carbon tend to change after some time where conductive plastic and cermet are not really affected. In essence, a stereo log pot using carbon would be more prone to be affected by tracking in the long run, it doesn't mean it is not as good though. For this preamplifier, the TKD makes a very good difference with tracking, especially at low volume.
I hope this helps a little.
Do
Thanks, Do.
Kind regards,
Drew
Ah, sorry, I was imprecise. I meant that I had read that the "feel" of turning the potentiometer is (allegedly) smoother on the "plastic" types.
Kind regards,
Drew
Hi Do,
Sorry I have not visited this thread in a while. It sounds like a ground loop. If there is no hum with one connected then it’s not the SMPS.
If your friend can post a sketch showing how things are connected taking care to show exactly where ground and 0v and earth/chassis ground are connected that would be helpful. A few high resolution photos showing details of connections is always helpful.
If the ground loop happens on mono blocks, it means there is a ground loop between the two that is in addition to the common ground they share at the RCA ground. This is an inadvertent “clean 0v” connection somewhere to a “dirty chassis/earth” ground.
Places to check:
1. Is the SMPS earth isolated from the output 0v?
2. Are RCA jacks isolated type or do they have their ground connected to chassis at feedthrough washer and nut?
3. Are the heatsinks connected to a star earth/chassis ground point? They should be.
4. Is there a ground loop breaker NTC (8D-20 or CL-60) between the star earth/chassis ground and 0v clean ground from the PSU? Add parallel 22nF 250v MKP cap to this NTC ground loop breaker. The clean ground is same as amplifier 0v ground, audio in ground, and speaker return ground.
5. Are there two SMPS 0v connected in common somehow? They should not be.
6. Use a linear 12v 1000mA Class 2 wall wart (the kind that powers old school routers or pencil sharpeners or other appliance). It needs to be 2 prong (no earth) and provide galvanic isolation from the mains and earth on mains. Power the DC-DC step up with this wall wart. This will disconnect the Aksa Lender from a possible earth mains ground return. Some SMPS like laptop 19v with 3 prong will have earth connected to the 0v terminal. This is a ground loop path. Eliminate it.
If I were to guess where the culprit is, I think that the SMPS for Mofo has a earth ground at IEC that is connected internally to 0v out to the amp. Or the SMPS powering the Aksa Lender has earth mains connected to 0v. That’s where the ground loop is and the fact that it is giga loud means it is picking up mains AC (50Hz) hum present in house mains earth ground.
Try those - but please provide diagram and photos.
Cheers,
X
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Building my AKSA-Lender all stock, as listed in the BOM and schematics, with errata from the GB pg. 1. Specifically for my MOFOs, which are working well now.
I was thinking to power mine at 48V.
First, I was planning to use a Meanwell LRS-100-24 for power behind a boost converter, but now I'm thinking of switching to a 19V/4.5A laptop supply + boost. Searching for a bit, I'm having a hard time finding a boost converter that hits above 35V. Anyone have a suggestion?
Second, When I tested the Dialight blue LED at 5.1v, it seemed bright enough with 10K resistor. Given that, shouldn't I use 100K on the PCB?
Last, it seems the power barrel connector in the schematic (X161) has open hole type mounting connectors, not PCB pins. I haven't figured out how I plan to encase this, so it may not matter; I may end up using a separately wired case-mount connector.
Kind regards,
Drew
I was thinking to power mine at 48V.
First, I was planning to use a Meanwell LRS-100-24 for power behind a boost converter, but now I'm thinking of switching to a 19V/4.5A laptop supply + boost. Searching for a bit, I'm having a hard time finding a boost converter that hits above 35V. Anyone have a suggestion?
Second, When I tested the Dialight blue LED at 5.1v, it seemed bright enough with 10K resistor. Given that, shouldn't I use 100K on the PCB?
Last, it seems the power barrel connector in the schematic (X161) has open hole type mounting connectors, not PCB pins. I haven't figured out how I plan to encase this, so it may not matter; I may end up using a separately wired case-mount connector.
Kind regards,
Drew
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Drew - I am running my stock Lender at 48V after the onboard cap-multiplier. In order to do that you have to feed the amp with around 52V. The meanwell you listed will work (but not give you the 48V rails), but I think it is an overkill. I use a 19V laptop supply with DC booster which I purchased locally. The advantage of the booster is that you can dial exactly into the required voltage.
https://www.diyelectronics.co.za/st...es/378-high-voltage-dc-dc-boost-2a-5-56v.html
Sorry - with the LED and barrel connector I cannot help you.
https://www.diyelectronics.co.za/st...es/378-high-voltage-dc-dc-boost-2a-5-56v.html
Sorry - with the LED and barrel connector I cannot help you.
Building my AKSA-Lender all stock, as listed in the BOM and schematics, with errata from the GB pg. 1. Specifically for my MOFOs, which are working well now.
I was thinking to power mine at 48V.
First, I was planning to use a Meanwell LRS-100-24 for power behind a boost converter, but now I'm thinking of switching to a 19V/4.5A laptop supply + boost. Searching for a bit, I'm having a hard time finding a boost converter that hits above 35V. Anyone have a suggestion?
Second, When I tested the Dialight blue LED at 5.1v, it seemed bright enough with 10K resistor. Given that, shouldn't I use 100K on the PCB?
Last, it seems the power barrel connector in the schematic (X161) has open hole type mounting connectors, not PCB pins. I haven't figured out how I plan to encase this, so it may not matter; I may end up using a separately wired case-mount connector.
Kind regards,
Drew
Something like this with a 12v or 19v or 24v wall SMPS or even 12v 1000mA Class 2 linear wallwart can work. These cost a bit more but are very quiet:
https://www.ebay.com/p/20002977581
These are $2 and can work well, but the one above is basically silent:
250/600W 10A Step Up DC Boost Converter Constant Current Power Supply LED Module | eBay
I have also used these with success, but some of them have died:
DC-DC Converter 10/12/15/20A150/250/300/400/1200W Step up Step down Buck Boosts | eBay
For LEDs use Ohm's law V=IR and solve for R to get about 2mA current through the LED. That is all you need because too much and it is annoyingly bright and reduces lifetime of LED. So for 48v,2mA, we get R=V/I=48v/0.002A=24k or a 22k is close enough.
Just solder connection wire between your panel jack barrel 5.5mm coax and the internal CLC filter.
You will need to calculate the RC time constant to make sure you get enough bass extension. I would want to set it to -3dB two octaves below 20Hz or 5Hz Fc depending on your amp's input impedance. Assuming it is 10kohms, you would need 3.3uF film cap for 5Hz. But if you just use a 10uF cap, you will be able to drive the occasional 3kohm load.
OK, thanks. I'll be hooking it up to an F4. I found a nice calculator online for this:
Coupling Capacitor Calculator by V-Cap
Coupling Capacitor Calculator by V-Cap
Nice to see someone finally putting the Aksa Lender to use with an F4. The inout impedance of the F4 is a fairly high 47kohm according to the manual. Hence, according to the online calc you linked, you want 3.3uF for good response down to 10Hz.
http://www.firstwatt.com/pdf/prod_f4_man.pdf
http://www.firstwatt.com/pdf/prod_f4_man.pdf
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