, think I will go for the regular ALPS RK27 20K Dual though, as the BOM says somewhere between 15 and 25K is ideal.
Potentiometers, again
I'm also in the process of assemblying my DCB1 and I'm looking for a pot to use. First option was some kind of relay attenuator with remote but budget is a bit tight right now so I'm setting for a cheap temporary replacement.
I read this article from Rod Elliott about a better volume control and wondered if I could not do something similar that could work fine with the DCB1. I'm a beginner in electronics so finding the answer took me some time and I'd like to share it here hoping that somebody can confirm I did not make mistakes.
If I understood what said in several posts here, in order to work fine the better volume control would need to have an output impedance similar to the one of a standard 20k pot and an input impedance possibly high and compatible with the sources I will use. I then calculated the input and output impedances for a standard 20k pot and for a 50 k linear pot with a 6.8k resistor added between ground and slider, as suggested in the Rod Elliott project. I put the the formulas I used next to the schematics below.
Putting the results of the calcs in graphs vs the percentage of the potentiometer stroke gives these plots
These seem to tell that if I use a 50k linear pot together with a 6.8k resistor I get an input impedence generally high (its min is 8.5k at maximum volume). This is fine for my source (a DAC with 80ohm output mpedance). The output impedence also seems correct, following the same behavior of the 20k pot.
Last piece of info is the attentuation vs pot stroke here below.
This also seems to have good behavior with decent linearity in the central range of the volume pot stroke.
Now the big question. Can I start to warm the soldering iron or do you see some mistake and I need to reconsider this?
I'm also in the process of assemblying my DCB1 and I'm looking for a pot to use. First option was some kind of relay attenuator with remote but budget is a bit tight right now so I'm setting for a cheap temporary replacement.
I read this article from Rod Elliott about a better volume control and wondered if I could not do something similar that could work fine with the DCB1. I'm a beginner in electronics so finding the answer took me some time and I'd like to share it here hoping that somebody can confirm I did not make mistakes.
If I understood what said in several posts here, in order to work fine the better volume control would need to have an output impedance similar to the one of a standard 20k pot and an input impedance possibly high and compatible with the sources I will use. I then calculated the input and output impedances for a standard 20k pot and for a 50 k linear pot with a 6.8k resistor added between ground and slider, as suggested in the Rod Elliott project. I put the the formulas I used next to the schematics below.
Putting the results of the calcs in graphs vs the percentage of the potentiometer stroke gives these plots
These seem to tell that if I use a 50k linear pot together with a 6.8k resistor I get an input impedence generally high (its min is 8.5k at maximum volume). This is fine for my source (a DAC with 80ohm output mpedance). The output impedence also seems correct, following the same behavior of the 20k pot.
Last piece of info is the attentuation vs pot stroke here below.
This also seems to have good behavior with decent linearity in the central range of the volume pot stroke.
Now the big question. Can I start to warm the soldering iron or do you see some mistake and I need to reconsider this?
Making a linear pot to a mimic a log one is an old trick that works. I had done this once to a Sfernice small white Lin pot. That was a really clean sounding pot. Alas it never had good very low level channel matching. Was shutting them off one by one. The //R quality mattered too as I recall.
Yes, I assumed I could omit the receiver based on two hypothesis:
1 if the two solutions compare well without the receiver they will also with it
2 if the receiver has high enough input impedance then it won't affect the actual values too much.
Is this correct? If not i will spend some more time on this later tonight
1 if the two solutions compare well without the receiver they will also with it
2 if the receiver has high enough input impedance then it won't affect the actual values too much.
Is this correct? If not i will spend some more time on this later tonight
Hi
I am aware of the various threads on the Mezmerize, but I cannot find what amounts to a basic instruction on the build. There are a few unexplained holes on the board and some ambiguity regarding 68 ohm resistors being doubled as examples of issues I have not been able to solve.
A conventional build set of instructions would help me greatly
Wayne
I am aware of the various threads on the Mezmerize, but I cannot find what amounts to a basic instruction on the build. There are a few unexplained holes on the board and some ambiguity regarding 68 ohm resistors being doubled as examples of issues I have not been able to solve.
A conventional build set of instructions would help me greatly
Wayne
Wayne hi
Tell me the unexplained holes. The 68 Ohm resistors should be doubled per side. I wasn't making pdf guides back then when DCB1 was developed, anyway it became "viral" as the project evolution process was unfolding in the threads and the builders learned along. The cart was put before the horse so to say. I should make a small basic hands on guide since its still being made by enough DIYers, you are right.
Tell me the unexplained holes. The 68 Ohm resistors should be doubled per side. I wasn't making pdf guides back then when DCB1 was developed, anyway it became "viral" as the project evolution process was unfolding in the threads and the builders learned along. The cart was put before the horse so to say. I should make a small basic hands on guide since its still being made by enough DIYers, you are right.
Thanks Salas
A guide would help the less experienced like me, particularly. They the DIY shop still sells it means that there must be a demand, so your efforts would not be for nothing.
My little issues are
1) the three holes near the centre of the board between the 10 ohm resistors and the small jumper
2) There is an extra LED site near 2k2 resistor that the Bill of Materials does not account for - should one be placed there?
3) Should the 2 x 300 ohm resistors be placed where indicated even if the jumper for 12 volt relays be used?.
Thank you again
Wayne
A guide would help the less experienced like me, particularly. They the DIY shop still sells it means that there must be a demand, so your efforts would not be for nothing.
My little issues are
1) the three holes near the centre of the board between the 10 ohm resistors and the small jumper
2) There is an extra LED site near 2k2 resistor that the Bill of Materials does not account for - should one be placed there?
3) Should the 2 x 300 ohm resistors be placed where indicated even if the jumper for 12 volt relays be used?.
Thank you again
Wayne
1. Test pads for probing and reading the regulators outputs +0- DC
2. Power on indicator LED. Can wire to a front panel LED from there. Can also remain unpopulated, no harm.
3. No. Only in case of must be using 5V relays. 12V ones are preferable. Don't mix types if having few of both.
Regards
Hello,
Wayne, you should find Tea-Bags blog and check out the links to builds there. They are verry good.
I am verry new to building stuff, like "don`t hold the end that get`s hot on the soldering iron new", and i used these pages to put together Mezmerize ans Hypnotize.
I also read the different treads with the pcb in front of me, so i know where on the board people are talking about.
If you buy a "kit" from Tea-Bag, he will send you what you need to populate the pcb.
Tell him you want the kit completely stock, and he will probably take out, or like he did for me label "optional" parts. It is then easy to populate the board.
Good Luck
Wayne, you should find Tea-Bags blog and check out the links to builds there. They are verry good.
I am verry new to building stuff, like "don`t hold the end that get`s hot on the soldering iron new", and i used these pages to put together Mezmerize ans Hypnotize.
I also read the different treads with the pcb in front of me, so i know where on the board people are talking about.
If you buy a "kit" from Tea-Bag, he will send you what you need to populate the pcb.
Tell him you want the kit completely stock, and he will probably take out, or like he did for me label "optional" parts. It is then easy to populate the board.
Good Luck
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hi guys,
Im in the process of putting the Mez b1 and Aleph J together and have a question about the ground connections on the input of the mez b1. in some builds you see that the diyer connected the rca jacks ground together and not connecting this to the input ground of the mez b1, in other builds you see that the diyer connnects every single input ground to the rca jack ground, which is the preferred way?
thanks in advance,
Leo
Im in the process of putting the Mez b1 and Aleph J together and have a question about the ground connections on the input of the mez b1. in some builds you see that the diyer connected the rca jacks ground together and not connecting this to the input ground of the mez b1, in other builds you see that the diyer connnects every single input ground to the rca jack ground, which is the preferred way?
thanks in advance,
Leo
Most builders who post photos they don't wire the PCB GND to chassis. In the odd event you may hear some buzz you can try it. There is a convenient GND pad at the output end of the PSUs section. There are three non designated voltage test pads, the middle one. Don't forget connecting to chassis the mains protective earth anyway.
Attachments
hi guys, back again, I have put the Mez B1 and Aleph J in the case i've build for the first listening test, the combination played great yesterday evening, this morning i've tried putting it on again but the led string (the series of 5 leds) on the v- side diddent light up, i will check the resistors tonight, but a question arises, is it a must to put some heatsinks on the IRFP's in a standard config?