Yes - leaded solder. The lead stops that from happening. 60/40 rosin core is fine. 63/37 also.
Lead-free solder sucks.
My favorite solders are
Kester "44" It has a TON of rosin flux. Makes really, really nice joints and flows better than anything I've used, due to the flux. Joints have a bit of a fluxy mess on them, but worth it.
Cardas Quad Eutectic - A 4-metal blend, mainly Tin and Lead, but with a couple percent of silver and copper as well. Low melting point, good flux, very easy to desolder. The silver is there not for any audiophile reasons but because silver plated contacts and wire will whisker and corrode in presence of non silver-bearing solder. The Cardas Quad is allegedly the same recipe that the Bell Telephone system used, where longevity and reliability was paramount.
Lead-free solder sucks.
My favorite solders are
Kester "44" It has a TON of rosin flux. Makes really, really nice joints and flows better than anything I've used, due to the flux. Joints have a bit of a fluxy mess on them, but worth it.
Cardas Quad Eutectic - A 4-metal blend, mainly Tin and Lead, but with a couple percent of silver and copper as well. Low melting point, good flux, very easy to desolder. The silver is there not for any audiophile reasons but because silver plated contacts and wire will whisker and corrode in presence of non silver-bearing solder. The Cardas Quad is allegedly the same recipe that the Bell Telephone system used, where longevity and reliability was paramount.
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Sadly, this is something that I only recently learned when I visited the production line of an aerospace defense contractor. I guess they are used to people not asking too many questions because the president of the company did a double take on the shop floor when I asked him a specific question about the physical configuration of the regulated power supplies that were coming off the line
Hello All,
My first post on this thread. First, many thanks for the ongoing support and contribution to this thread, it makes a fascinating reading. Special mention to 6L6 for the build guide, patience and guidance, multiple others for the knowledge and expertise. And espcially to Wayne and Nelson for their support of DIYers.
I received my Pearl 2 boards and they are almost completely populated. One question I am debating is the resistive loading. I have currently an Ortofon with '10 Ohm or higher' recommended loading, but will have 2-3 more cartridges in the future, some mention 90 Ohm or higher.
I would like to avoid having to resolder resistors and therefore would like to use the solution mentioned in post 2717 of using a rotary switch in parallel to R19 [presumably using R20 holes?]. I have a 12 position MBB rotary switch I would like to use and thought I'd start at 7 Ohm and use a 1.4 factor to get to 320 Ohm at the last position [power of 2 series]. Does such a scheme make sense? Should I use different values? I know it's somewhat over the top, but isn't DIY all about pushing the envelope, or at least the wallet?
My first post on this thread. First, many thanks for the ongoing support and contribution to this thread, it makes a fascinating reading. Special mention to 6L6 for the build guide, patience and guidance, multiple others for the knowledge and expertise. And espcially to Wayne and Nelson for their support of DIYers.
I received my Pearl 2 boards and they are almost completely populated. One question I am debating is the resistive loading. I have currently an Ortofon with '10 Ohm or higher' recommended loading, but will have 2-3 more cartridges in the future, some mention 90 Ohm or higher.
I would like to avoid having to resolder resistors and therefore would like to use the solution mentioned in post 2717 of using a rotary switch in parallel to R19 [presumably using R20 holes?]. I have a 12 position MBB rotary switch I would like to use and thought I'd start at 7 Ohm and use a 1.4 factor to get to 320 Ohm at the last position [power of 2 series]. Does such a scheme make sense? Should I use different values? I know it's somewhat over the top, but isn't DIY all about pushing the envelope, or at least the wallet?
Since it doesn’t come in kit form, I had to buy a preassembled XP-15...WOW! That’s all I’ll say about that.
However it gives me perspective on the Pearl II which is a great phono-pre in it’s own right. I’ve had a few really nice phono stages at home lately, and the Pearl II is playing in the same ballpark. The Pearl II has served me well and will go on to play beautiful music for someone else I’m sure. What a gift to the DIY community...thanks Wayne!
However it gives me perspective on the Pearl II which is a great phono-pre in it’s own right. I’ve had a few really nice phono stages at home lately, and the Pearl II is playing in the same ballpark. The Pearl II has served me well and will go on to play beautiful music for someone else I’m sure. What a gift to the DIY community...thanks Wayne!
I would start a little higher, I think there are not that many cartridges that need a 7 Ohm loading. Medium output mc's (that go well with the 55dB gain of the Pearl II) like a loading of aroud 400 Ohm - 1k or something like that. Starting at 33 Ohm will get you to around 1k3 (50 -> 2k). I would also consider leaving one position on the switch unoccupied which would get you 47k for high output mc's.
I've got a slight rebuild of my Pearl planned where I use dipswiches for gain, capacitance and resistance. The ability to parallell more resistors gives you lots of loading options.
I finally broke down and bought a decent MC cart, an Audio Technica AT33PTG/II. WOW what a difference!! I was using an Ortofon 2M Red that came with the turntable. It generally sounded pretty good but I struggled to get it to work with the Pearl2 for over 2 years before this. I could not get rid of the overload/distortion on voices and highs. I tried EVERYTHING. I could get it a little better but it was never right. It's 5mv output is just too much for the Pearl2. The new cartridge is only 0.3mv and is just wonderful. Well worth the upgrade to finally hear the Pearl2 sing as it was intended. Thank you Nelson!!
Well, nothing really special. Parallel the 47k input resistor with a dipswitch with 12 choices, another dipswitch with 4 choices for input capacitor and a dipswitch that lets you choose gain between 42.5 and 65 dB in 10 steps.
Then probably a few slight changes in values in the RIAA section as suggested by Jackinnj to make it more linear and a change in capacitor value to slightly decrease the low end roll-off.
The PSU will be changed to CRCRC, and I will experiment a bit with the onboard regulators to get it more quiet. Add in a few fancy Mundorf capacitors and that's about it.
But other projects await my attention, so it might be this winter ore even later before I get to it.
Into my second Pearl Two build! On this build I’d like to be able to adjust both Gain and Cartridge Loading. I’m doing this for the same reason as many others have, to be able to try a variety of MC and MM cartridges.
I am comfortable with my understanding of how to implement the Variable Gain at R14 which I will execute using a dip switch or sockets with 300r, 600r, and 1k resistors.
I am confused about loading. Based on some the cartridges I currently own and am looking into trying I believe I will need a range of values of 47k to 816ohm. Wayne’s Pearl Two Phono Stage manual/article states that “R20 is a user provided resistor value that sets the input load for the cartridge if not the default 47 Kohm.” Yet in the build threads builders are referring to C22 and using capacitor values in the range of 100pF, 150pF, 220pF, and 330pF.
Are the capacitors used in conjunction with R20 resistors to vary the cartridge loading and this just hasn’t been noticed on my part or is cartridge loading done either with C22 or R20 but not both ?
Do I just not understand what C22 does?
Why did Wayne point to using R20 for cartridge loading but not mention C22?
If using just R20 how does one calculate resistor values?
If using just C22 how does one calculate the capacitor values and how does this change the cartridge loading?
If both C22 and R22 are used how are those values derived?
I have looked at vdi_nenna’s implementation here (http://www.diyaudio.com/forums/analogue-source/224439-mc-mm-resistor-capacitor-loading-7.html)so that is obviously some of the answer but I’d really like some explanation as to the hows and whys mainly because I don’t trust my self to get this right and I’d like to learn something in the process. An answer to each question would be really helpful. Many thanks!
I am comfortable with my understanding of how to implement the Variable Gain at R14 which I will execute using a dip switch or sockets with 300r, 600r, and 1k resistors.
I am confused about loading. Based on some the cartridges I currently own and am looking into trying I believe I will need a range of values of 47k to 816ohm. Wayne’s Pearl Two Phono Stage manual/article states that “R20 is a user provided resistor value that sets the input load for the cartridge if not the default 47 Kohm.” Yet in the build threads builders are referring to C22 and using capacitor values in the range of 100pF, 150pF, 220pF, and 330pF.
Are the capacitors used in conjunction with R20 resistors to vary the cartridge loading and this just hasn’t been noticed on my part or is cartridge loading done either with C22 or R20 but not both ?
Do I just not understand what C22 does?
Why did Wayne point to using R20 for cartridge loading but not mention C22?
If using just R20 how does one calculate resistor values?
If using just C22 how does one calculate the capacitor values and how does this change the cartridge loading?
If both C22 and R22 are used how are those values derived?
I have looked at vdi_nenna’s implementation here (http://www.diyaudio.com/forums/analogue-source/224439-mc-mm-resistor-capacitor-loading-7.html)so that is obviously some of the answer but I’d really like some explanation as to the hows and whys mainly because I don’t trust my self to get this right and I’d like to learn something in the process. An answer to each question would be really helpful. Many thanks!
R20 et R19 do the cartridge loading for MC cartridges.
C22 is for MM cartridges (I didn't put any caps at this place on my Pearl2).
Input load is (R20*R19)/(R20+R19). R19 being very high (47K), the result is more or less the value of R20 (on mine, I didn't solder R19 and used IC socket to swap R20 easily).
So for an adjustable load, you juste have to choose different R20 values (100, 200, 400, 800 for exemple) and use a switch to choose between them without opening the box (or sockets if you don't mind opening it).
C22 is for MM cartridges (I didn't put any caps at this place on my Pearl2).
Input load is (R20*R19)/(R20+R19). R19 being very high (47K), the result is more or less the value of R20 (on mine, I didn't solder R19 and used IC socket to swap R20 easily).
So for an adjustable load, you juste have to choose different R20 values (100, 200, 400, 800 for exemple) and use a switch to choose between them without opening the box (or sockets if you don't mind opening it).
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Thank you, Folkdeath95 this is helpful. I may not end up with MM in play, though I do have a Technics EPC-U1200 mm cartridge, it is unlikely to be moved to the system the Pearl Two will reside in. So at this point I don’t need to be concerned with C22. It is clear to me now that vdi_nenna is referring to MM setting where the capacitors are concerned.
The formula for R19 and R20 is the parallel resistor value calculation formula, again clear to me now, as R20,R19 are in parallel, which are the parallel resistors vdi_nenna referred to in his post. Duh! Life is harder for us slow folks!
How does one calculate how much the decibel gain is based on the the R19 and R20 resistor pairs?
As gain can be set using R19 and R20 -or- R14 by itself is one way preferable to the other?
Thank you craigtone, I purchased some of the sockets you used ages ago!
The formula for R19 and R20 is the parallel resistor value calculation formula, again clear to me now, as R20,R19 are in parallel, which are the parallel resistors vdi_nenna referred to in his post. Duh! Life is harder for us slow folks!
How does one calculate how much the decibel gain is based on the the R19 and R20 resistor pairs?
As gain can be set using R19 and R20 -or- R14 by itself is one way preferable to the other?
Thank you craigtone, I purchased some of the sockets you used ages ago!
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Is there an advantage or disadvantage to adjusting/increasing gain at R14 (as some have done) over using R20 to adjust/increase gain?
Also How does one calculate how much the decibel gain is based on using the R19 and R20 parallel resistors? So if R19 is 47k and R20 is 560r then the value of those two resistors in parallel equals 553.41r, using the 553.41 value what is the gain in dBs and how is that calculated?
Also How does one calculate how much the decibel gain is based on using the R19 and R20 parallel resistors? So if R19 is 47k and R20 is 560r then the value of those two resistors in parallel equals 553.41r, using the 553.41 value what is the gain in dBs and how is that calculated?
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AFAIK, R19/R20 don't set gain but only input load.
To set gain, here is a shematic with formulas posted somewhere before in this thread (I'm afraid I forgot who is was
):