carlosfm said:One cap on each side of the op-amp, please.
Putting it on the other side would increase the total bypass path length, so, no.
With the new layout, the load ground, bypass ground, and even the + and - input grounds are all connected together within a few mm. (Those who look carefully will note that they were only a little longer than that for the old version, too, only the bypass ground was too far away from the opamp to allow for short connections to the power pins, hence the change.)
The shaded green ground "bus" would be used in the simple case with a 3 wire power cord. The rigorous version for retentive types would just use the green lines, forming an "H" with the connection being made at the bypass caps and requires four wires back to the transformer/diodes.
I'll let someone else experiment with CRC. I mucked around with that ages ago and did not like the results at all. Besides adding components isn't in the design brief.
I agree with Peranders that in general the feedback loop should be as short as possible, but with an active eq its always going to be relatively sprawling. Here, in the interests of a compact ground and bypass lengths I relaxed the feedback length a little, yes.
rjm
on the MC loading issue,
One can conveniently increase the gain in the circuit to the point where using it with MC cartridges is feasible.
I recently started using a Denon DL 103 (0.3mV) with the VSPS. I increased the gain to 46db, which isn't much but is plenty for my current system, and changed the load resistor to 1.5k (or whatever). For me, its fine. It might not be optimal (well it *isn't* technically, by all manner of reasons) but its very quiet (no hum and no hiss audible at anything close to normal listening levels) and sounds great.
rjm
One can conveniently increase the gain in the circuit to the point where using it with MC cartridges is feasible.
I recently started using a Denon DL 103 (0.3mV) with the VSPS. I increased the gain to 46db, which isn't much but is plenty for my current system, and changed the load resistor to 1.5k (or whatever). For me, its fine. It might not be optimal (well it *isn't* technically, by all manner of reasons) but its very quiet (no hum and no hiss audible at anything close to normal listening levels) and sounds great.
rjm
rjm said:
So please don't use the OPA2134.
Stick to the NE5532.
You're putting the caps away from the regulators now.
They like caps near them.
I agree with the resistor on the PSU, I always use it before the caps on the op-amp.
Although I use smaller values (10~22 ohms).
And I agree also that you should try to shorten the feedback loop, too much lost space there.
If you don't need help for making a simple but decent SOUNDING phono pre, then I don't understand why was this thread started.
Maby you're willing to sell kits of this pre?
This thread has probably run its course. I'd like to thank everyone who contributed. Peer review, loud and chaotic though it might be, is still really helpful for me to add refinements to a design.
I'm particularely impressed with the dicipline shown by people posting to limit suggestions to those which added materially neither to the cost nor the complexity of the project. Fanboy comments like LM79xx suckx, NE5534 suckx were mercifully absent.
Thanks especially to Carlos for reminding me just how sensitive op-amps can be to seemingly inconsequencial layout changes.
The revised layout is shown below. If anyone thinks they can do a better job pm me. The original file is just an MSWord doc and I'd be happy to email it to you to play with to your hearts content. Credit please, though, if you end up using it as a base for your own work.
To them as don't like the grouding: The non-inverting and inverting input share 0.1" of common wire to the load star. And that's deliberate. I challenge you to find any issue more significant.
To them who don't like the position of the bypass caps. If you aren't going to take the trouble to listen to my side of the arguement there is little point, but once again: 10mm of lead at ground potential is equivalent to 10mm at Vcc as far as lead inductance goes, so its the distance from the power pin to the load return that is important, not the physical proximity of the cap to the power pin.
The feedback loop position allows the flexibility to accept caps of various sizes, using MKS or suchlike it could be slightly smaller but not significantly so. It'll never be pin-to-pin 8mm a la gainclone.
CRC is to first order a simple trade of power supply impedance for lower noise. It would likely also damp to insignificance any oscillation due to layout trace inductance of the kind responsible for the quirky dependence of the sound on capacitor position. Aware as I am of the benefits I an not enamoured with the sonic result. I prefer my power to be both low impedance and low capacitance. YMMV as ever.
Hush now, Peace! (or go make your own layout! )
Richard
I'm particularely impressed with the dicipline shown by people posting to limit suggestions to those which added materially neither to the cost nor the complexity of the project. Fanboy comments like LM79xx suckx, NE5534 suckx were mercifully absent.
Thanks especially to Carlos for reminding me just how sensitive op-amps can be to seemingly inconsequencial layout changes.
The revised layout is shown below. If anyone thinks they can do a better job pm me. The original file is just an MSWord doc and I'd be happy to email it to you to play with to your hearts content. Credit please, though, if you end up using it as a base for your own work.
To them as don't like the grouding: The non-inverting and inverting input share 0.1" of common wire to the load star. And that's deliberate. I challenge you to find any issue more significant.
To them who don't like the position of the bypass caps. If you aren't going to take the trouble to listen to my side of the arguement there is little point, but once again: 10mm of lead at ground potential is equivalent to 10mm at Vcc as far as lead inductance goes, so its the distance from the power pin to the load return that is important, not the physical proximity of the cap to the power pin.
The feedback loop position allows the flexibility to accept caps of various sizes, using MKS or suchlike it could be slightly smaller but not significantly so. It'll never be pin-to-pin 8mm a la gainclone.
CRC is to first order a simple trade of power supply impedance for lower noise. It would likely also damp to insignificance any oscillation due to layout trace inductance of the kind responsible for the quirky dependence of the sound on capacitor position. Aware as I am of the benefits I an not enamoured with the sonic result. I prefer my power to be both low impedance and low capacitance. YMMV as ever.
Hush now, Peace! (or go make your own layout!
)Richard
Attachments
I am from China and very interested in this pre amplifier but i cannot reach the link to the circuit maybe because i am so far from this website. A few days ago i bought a Linn lp-12 and very enjoyed in it's music but i am not satisfied in the preamp, would anybody pls send the circuit to my email: zjianjun11@yahoo.com.cn,thanks a lot!
Is the LM358 usable in this great circuit?
Is the LM358 usable in this great circuit?
I have one laying around and do want to use for one of my turnables.
It doesn't have to be high end, not for this turntable.
The turntable im talking has a simple mm cardrige.
So no high end needed here.
You can see the datasheet of the LM358 here
http://www.national.com/ds/LM/LM158.pdf
It is used in this mm pre before, but i do not like this circuit
http://members.shaw.ca/roma/twelve.html
I think the best possible option would be your hi-z version.
Hope some of you can help me with this.
Thanks
Erwin
Is the LM358 usable in this great circuit?
I have one laying around and do want to use for one of my turnables.
It doesn't have to be high end, not for this turntable.
The turntable im talking has a simple mm cardrige.
So no high end needed here.
You can see the datasheet of the LM358 here
http://www.national.com/ds/LM/LM158.pdf
It is used in this mm pre before, but i do not like this circuit
http://members.shaw.ca/roma/twelve.html
I think the best possible option would be your hi-z version.
Hope some of you can help me with this.
Thanks
Erwin
Need an input cap
Hello everyone,
I have build this simple and very nice sounding phono pre amp.
Got only one problem.
The turntable i have uses a muting circuit when the needle is lifted
of the record or when the arm is traveling.
This i know is not the best option, but i restored it in its original state.
And i want to keep it that way.
But i hear plopping noises when the circuit is activated.
I had two 220nf caps laying around so i thought i give them try and
put one on each input of phono pre amp.
That did the trick.
I hear only one plop when the turntable is switched on.
My question is what would be the best capacity for an input cap?
Hope some of you can help me with this.
Erwin
Hello everyone,
I have build this simple and very nice sounding phono pre amp.
Got only one problem.
The turntable i have uses a muting circuit when the needle is lifted
of the record or when the arm is traveling.
This i know is not the best option, but i restored it in its original state.
And i want to keep it that way.
But i hear plopping noises when the circuit is activated.
I had two 220nf caps laying around so i thought i give them try and
put one on each input of phono pre amp.
That did the trick.
I hear only one plop when the turntable is switched on.
My question is what would be the best capacity for an input cap?
Hope some of you can help me with this.
Erwin
Running in this Pre Amp
Hello,
Iv'e build this great Phono Pre with the 5532 chip.
Sounds very nice.
I got another question.
I do not like to play records night and day to run (burn) in this Pre.
Isn't it enough to just leave it on? (i wasn't planning on turning it off anyway)
Pleace give me some insite on this.
Bye.
Hello,
Iv'e build this great Phono Pre with the 5532 chip.
Sounds very nice.
I got another question.
I do not like to play records night and day to run (burn) in this Pre.
Isn't it enough to just leave it on? (i wasn't planning on turning it off anyway)
Pleace give me some insite on this.
Bye.
input capacity
The correct input capacity is the capacity which causes the Q of the resonant circuit formed by the cartridge inductance, load resistor and the total shunt capacity to be between 0.5 and 0.7.
The formula is Q=Rsquareroot(C/L) where R is the load resistor, C is the total shunt capacity in the cartridge, tonearm wiring, interconnects and preamp and L is the cartridge inductance .
For a Shure V-15 cartridge with about 0H5 inductance, C calculates to be between 65-120pF.
Note that this is less than half of what Shure recommends.
High inductance cartridges are difficult to terminate correctly. Regards,
Ray
The correct input capacity is the capacity which causes the Q of the resonant circuit formed by the cartridge inductance, load resistor and the total shunt capacity to be between 0.5 and 0.7.
The formula is Q=Rsquareroot(C/L) where R is the load resistor, C is the total shunt capacity in the cartridge, tonearm wiring, interconnects and preamp and L is the cartridge inductance .
For a Shure V-15 cartridge with about 0H5 inductance, C calculates to be between 65-120pF.
Note that this is less than half of what Shure recommends.
High inductance cartridges are difficult to terminate correctly. Regards,
Ray
Go with the lo-z version
Hello Mattjk,
Just build the lo - z version, you can find it here.
http://www.geocities.com/rjm003.geo/rjmaudio/diy_pho5.html
I could not get some of the parts for the hi - z version, so i build the lo - z version those parts are easy to get.
It sounds very nice.
It's playing now for about 4 weeks and sounds much better then in the beginning.
Im very happy with this phono pre, and im playing my old records on a dayly basis now.
Good luck on building this pre.
mattjk said:I want to built this preamp.
Anyone know where I can find a 1,0nF Polypropylene film and foil cap??? I've tried mouser and digikey.
Hello Mattjk,
Just build the lo - z version, you can find it here.
http://www.geocities.com/rjm003.geo/rjmaudio/diy_pho5.html
I could not get some of the parts for the hi - z version, so i build the lo - z version those parts are easy to get.
It sounds very nice.
It's playing now for about 4 weeks and sounds much better then in the beginning.
Im very happy with this phono pre, and im playing my old records on a dayly basis now.
Good luck on building this pre.
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