Thanks! As mine are built on perfboard different pinout would't matter.
Probably you're right and I wouldn't hear a lot of difference (measure maybe..). But one has got to do something after years of not tweaking anything
I have some wishes for my pearl 2, like soldering in some pins which let me change load and gain resistors easily. At the same time I could give the PSU and regulators a little upgrade.
Probably you're right and I wouldn't hear a lot of difference (measure maybe..). But one has got to do something after years of not tweaking anything
I have some wishes for my pearl 2, like soldering in some pins which let me change load and gain resistors easily. At the same time I could give the PSU and regulators a little upgrade.The ability to quickly and easily swap load resistance, input capacitance, and gain was a feature i really wanted. I had thought about using sockets, but that required powering down the system removing the box from my stand and opening up the top, waiting for the caps to discharge and then reassembling. eventhough i wield a soldering gun, i wanted to limi the risk of shock by reducing exposure to the boards. Most of all being able to make adjustment on the fly allowed me to hear the effect of my changes back to back.
I used a good quality rotary switch and populated it with all the likely load resistance values i might need for mc carts, mc carts with a step up transformer, and mm carts, so i could swap headshells and tune load on the fly.
I did the same for gain resistors and input caps. Though the input caps dont make a difference on mc carts.. So i havent needed this feature and in retrospect wish i hadent bothered with variable input cap settings.
Its been great. I just recently acquired a very nice step up tranaformer and it took only 30 seconds to plug it in and change my cart loading and gain to the appropriate levels. After half an hour of listening i was able to fine tune the loading to give me the right high/low/midrange balance i like, and match the pearl2 output gain to roughly match my disk player and dac, so volumes are consistent from source to source at my preamp.
More loading in increases bass output at the sacrifice of high and mid presence/clarity. Less leans the bass and makes the sound more treble forward. I think of it like tightening a drum skin. Not to tight or nit too loose, just right.
Consider switches. Saves time and effort and makes adjustment and tweaking a breeze. I havent found any audio drawbacks to using a switch vs soldering only a single load resistor in
I used a good quality rotary switch and populated it with all the likely load resistance values i might need for mc carts, mc carts with a step up transformer, and mm carts, so i could swap headshells and tune load on the fly.
I did the same for gain resistors and input caps. Though the input caps dont make a difference on mc carts.. So i havent needed this feature and in retrospect wish i hadent bothered with variable input cap settings.
Its been great. I just recently acquired a very nice step up tranaformer and it took only 30 seconds to plug it in and change my cart loading and gain to the appropriate levels. After half an hour of listening i was able to fine tune the loading to give me the right high/low/midrange balance i like, and match the pearl2 output gain to roughly match my disk player and dac, so volumes are consistent from source to source at my preamp.
More loading in increases bass output at the sacrifice of high and mid presence/clarity. Less leans the bass and makes the sound more treble forward. I think of it like tightening a drum skin. Not to tight or nit too loose, just right.
Consider switches. Saves time and effort and makes adjustment and tweaking a breeze. I havent found any audio drawbacks to using a switch vs soldering only a single load resistor in
Not a bad idea. I might go for dip-switches like in the XP15.
Can you also lower the gain by increasing R14? For instance: raising R14 to 6k would give 40dB gain, better for MM cartridges. Or does the amp get unstable below a certain gain (same as when raising the gain too much)?
I've been studying the picture of the XP15 PSU. Is it RCRC that I see? 8 large capacitors, 4 per rail I guess. R, 1C, R 3C parallell?
Can you also lower the gain by increasing R14? For instance: raising R14 to 6k would give 40dB gain, better for MM cartridges. Or does the amp get unstable below a certain gain (same as when raising the gain too much)?
I've been studying the picture of the XP15 PSU. Is it RCRC that I see? 8 large capacitors, 4 per rail I guess. R, 1C, R 3C parallell?
More numbers after the decimal.
In reality, the Lipshitz R1 works out to (Zin+R1)||R_Load,
I measured Zin which is a little lower than 499R
so (493+6810)||100,000=6805
Play around with R_Load in a simulator and you'll see how it affects the response curve.
Hi I am a newbie and is considering to build a Pearl 2. I want to have better bass response (low bass) and is currently using speaker with 26Hz bass response. What value of resistor would be optimal to hit these low frequency? I read that increasing the C12 value would increase bottom end. Please advise.
davynkh: Yes, as Wayne's article says on Passdiy, you can increase C12 to lower the bass roll off. On my Pearl2 I think I increased C12 from 0.1 to 0.2 uF to lower the cutoff frequency to 2/3 of original. I think Wayne has it start rolling off at about 30 Hz so my change lowered it to 20 Hz. However, there are other things to consider. For example, if your speakers are ported, they will unload at subsonic frequencies. I have seen woofers about to bottom out from a slight warp in a lp record. So you do want some sort of rumble filter or low freq roll off to protect from that. Besides, record manufacturers roll off the deep bass anyway when cutting a record, some more than others. My subwoofer has an adjustable rumble filter, so I was ok.
BTW, my pearl2 sounds beautiful! I am still amazed with it, coupled with my Maplenoll air bearing turntable and a DH 110. In a few days I will try to post some pics along with some more tips.
BTW, my pearl2 sounds beautiful! I am still amazed with it, coupled with my Maplenoll air bearing turntable and a DH 110. In a few days I will try to post some pics along with some more tips.
Thanks Propitious and Malotron for your advise.
I will build a standard version and then tweet the C12 for better bass.
I also like to have a switch on the fly (dip switch) for changing cartridge. Presently I am using a Ortofon 2M Red but I do have a Transfiguration Sprite Moving Coil.
I read somewhere on any thread deploying different load value at R20 for load.
What is the position I need to deploy for Capacitance and Gain?
Could you guys advise which position takes care of these two?
And is it necessary to change Capacitance setting? I notice some Phono stage sold in the market only allow adjustment for Load and Gain only.
What would be the load, capacitance and gain required to cater for most Moving coil cartridge?
I will build a standard version and then tweet the C12 for better bass.
I also like to have a switch on the fly (dip switch) for changing cartridge. Presently I am using a Ortofon 2M Red but I do have a Transfiguration Sprite Moving Coil.
I read somewhere on any thread deploying different load value at R20 for load.
What is the position I need to deploy for Capacitance and Gain?
Could you guys advise which position takes care of these two?
And is it necessary to change Capacitance setting? I notice some Phono stage sold in the market only allow adjustment for Load and Gain only.
What would be the load, capacitance and gain required to cater for most Moving coil cartridge?
DH-110 had an MC assembly which could be purchased for some tens of dollars. In itself it's a very nice pre-amplifier. There's a DIYAUDIO thread on this preamp.
Thanks! I finally had a chance to bust out the soldering iron and give this a try. Swapped out the 10R at R21-24 for 22R (because that's what I had handy) and put an 8k2 at R10. Q3 voltages are now 8.43 / 8.31 / 7.68. So that seems like a step in the right direction. But R21-24 in voltages are now .13. Any thoughts?
Good point - thanks!
Wired up the RCA jacks and fired the whole thing up - and had HORRIBLE hum with music only barely coming through. Spent about 10 minutes cursing before I realized that I had mounted the RCA ground collars between the case and the nylon washers. Oops!
Fixed that and music started coming through and sounding pretty good. But I am getting some crackling/distortion in one channel (interestingly enough, not the channel where I was having voltage problems and had to use the 20 ohm resistors) and that channel seems louder than the other.
I'm using an AT150 cartridge - I think Eric found that using a 100K resistor in Cx got rid of the distortion he was experiencing with that cartridge. So I guess I'll give that a try next.
Still not sure how to address the volume imbalance between channels, though - I suppose I could get a test tone record and measure the output signal from each channel and then try to tweak values accordingly. But if anybody has any different suggestions I would love to hear them.
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Yep, Jack suggested a 100k resistor in the Cx position and this solved the problem for me.
In its original configuration, the Pearl II output level was too high for my Marantz pre. It sounded terrible and caused the "PEAK" indicator to light and stay lit as soon as the needle hit the vinyl. I've now built a BA-3 preamp with a volume control before the BA-3 boards, so it doesn't matter any more. I actually forgot the 100k was in place
On another topics, I presume it is OK to parallel a second set of RCAs on the back of my Pearl if I separate them from the first set of RCAs with a ~100R resistor. Would this cause any problems that I am not thinking about?
Spent some time doing more thorough investigation what influence output caps have on overall sound.
The setup: modified Lenco TT, RB 300 tonearm, Benz Ace S cartridge -> Pearl II phono with Salas shunts -> DCB1 buffer -> E-MU Tracker pre sound card -> laptop (Audacity software).
Caps:
El
Elna Silmic II 10 µF 25V (kindly received from 6L6)
Nichicon bi-polar ES 22 µF 50V
Film PP
M Cap Supreme (simple, no silver, gold or oil) 2.7 µF 800V
Vishay MKP416 0.1 µF
Combinations:
Silmic II 10 µF + Vishay 0.1 µF (DCB1 bypassed, phono -> soundcard direct)
Silmic II 10 µF + M Cap 2.7 µF
M Cap 2.7 µF + Vishay 0.1 µF
M Cap 2.7 µF no bypass cap (suspected oscillation)
Nichicon ES 22 µF + Vishay 0.1 µF
Nichicon ES 22 µF + M Cap 2.7 µF
Tracks:
Pere Ubu – Final solution (2001 reissue, Get Back)
Can – Moonshake (1973, United Artists)
Anika – Yang Yang (2010, Invada)
Art of noise – Opus for four (1987, Chrysalis)
One more track is omitted from the bundle because of huge size already:
Wav files here (664MB) :
http://we.tl/KzIg4zaN5n
Conclusions are not that easy to make. M cap 2.7 µF + Vishay 0.1 µF shines in midrange. While Silmic and Nichicon combinations provides a fuller sound.
I would be very interested what others hear.
The setup: modified Lenco TT, RB 300 tonearm, Benz Ace S cartridge -> Pearl II phono with Salas shunts -> DCB1 buffer -> E-MU Tracker pre sound card -> laptop (Audacity software).
Caps:
El
Elna Silmic II 10 µF 25V (kindly received from 6L6)
Nichicon bi-polar ES 22 µF 50V
Film PP
M Cap Supreme (simple, no silver, gold or oil) 2.7 µF 800V
Vishay MKP416 0.1 µF
Combinations:
Silmic II 10 µF + Vishay 0.1 µF (DCB1 bypassed, phono -> soundcard direct)
Silmic II 10 µF + M Cap 2.7 µF
M Cap 2.7 µF + Vishay 0.1 µF
M Cap 2.7 µF no bypass cap (suspected oscillation)
Nichicon ES 22 µF + Vishay 0.1 µF
Nichicon ES 22 µF + M Cap 2.7 µF
Tracks:
Pere Ubu – Final solution (2001 reissue, Get Back)
Can – Moonshake (1973, United Artists)
Anika – Yang Yang (2010, Invada)
Art of noise – Opus for four (1987, Chrysalis)
One more track is omitted from the bundle because of huge size already:
Wav files here (664MB) :
http://we.tl/KzIg4zaN5n
Conclusions are not that easy to make. M cap 2.7 µF + Vishay 0.1 µF shines in midrange. While Silmic and Nichicon combinations provides a fuller sound.
I would be very interested what others hear.
Just to share, it turns out I had similar problems as chryses the JFETs I got from passdiy 2SK170 was hotter, R21 measured 0.071V. Resulting voltage at R10 was 6.9V, Vc of Q10 was 6.4V, Ve was 6.28V. So Q10 cascode was operating in heavy saturated range, to the point that the base current was starting to reverse bias, Q10's base - collector junction. So what I did was change R9 to ~250, 499||499 because that's what I had on hand. So now Vc of Q10 is 12.8v, Vb is 9.26v, Ve is 8.6v. Haven't had a chance to listen to it yet as the time is now 1.30am. But at least the cascode stage is no longer saturated. I'm sure I reduce the gain and lowered the output impedance a bit of the first stage. I don't need as much gain as I'm using Ortofon Red 2m and have not swap to the Denon HOMC I bought, yet.
Are you having this issue with both boards or just one? One set of the JFETs I got from passdiy worked fine, but the other set was too hot. And I can't seem to tweak things now to get the channels to sound the same (though I have no expertise in this regard) - changing around resistors as Wellerman suggested got the voltages on the one board more in line with the published values, but the bottom end on that board is rolled off and its sounds quieter than the other channel.
In any event, I would be very interested to know how your Pearl2 sounds with an MM cart (once you hook it up). Did you go with Jack's modified values for MM carts earlier in the thread?
Hi there, both boards behave the same. That is to say both set were hot and same current give take 0.1mA. The Pearl sound always felt like there was some distortion, I ended up buying a new TT Project RPM1.3 and Schiit Mani to verify that issue was not with TT I inherited ( Thorens 160) but with the Pearl. At that time the high was very poor, the gain was way too much the setup was very prone to hum and also the TT arm send to be a good antenna. I ended tweaking the output feedback to reduce the CL gain by 12dB which improves things a little but fundamentally still off. And using Jack's RIAA filter, which did improve the highs. But still far off.
Today I had a quick listen and the sound is completely changed. The treble is what I expect now the him is much lower (the residual is mostly if not partly cause by the Pearl PSU transformer residing in the same chassis, I plan to move that to different chassis now that the sound is good) and the vocals are still just as sweet. The bass is down a bit but that maybe my doing because there was too much bass back then and I don't have a good reference to compare the before and after. I plan to change the source resistors to higher value than current to lower the current through the JFETs down to between 1 ~ 4mA. And reset back the collector resistor to 499ohm to see which sounds better.
Today I had a quick listen and the sound is completely changed. The treble is what I expect now the him is much lower (the residual is mostly if not partly cause by the Pearl PSU transformer residing in the same chassis, I plan to move that to different chassis now that the sound is good) and the vocals are still just as sweet. The bass is down a bit but that maybe my doing because there was too much bass back then and I don't have a good reference to compare the before and after. I plan to change the source resistors to higher value than current to lower the current through the JFETs down to between 1 ~ 4mA. And reset back the collector resistor to 499ohm to see which sounds better.