Looking for discrete high performance linestage design with 12v rails

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#22
enregistree said:
If there is no need for voltage gain, and no SE-BAL conversion needed, then simple is better – volume control at input and high gm JFET buffer loaded at source with matched JFET (DC coupled) to drive power amp input and interconnect cables.
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That is also my experience. Also Andrea Ciuffoli's MOSFET version provides excellent results (10mA - 500mA scalable idle current - depended from the number and capacity of the cable connector to the power amp).
the Power Folllower
The use of MOSFET version with extrem low input capacitance isn't very important by the source follower topology.
RBorkowski said:
jmillerdoc,

Here is a very high performance balanced input linestage designed for a bipolar 12 volt supply. Low distortion - 0.000082% THD. Can be used single ended too, just tie either input to common. Output will remain the same regardless balanced or single ended.

I provided an LTSpice file of it if you are so inclined.

Enjoy...

Best Regards,

Rich
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From the audible view, there is no justification for this effort. Despite the much more better measured results of such an audio line stage I am sure, that Andrea Ciuffoli's MOSFET version provides the better sound by a listening test, if the adjusted idle current is not too low (>100mA).
 
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#23
jmillerdoc said:
PCBexpress is insane...they would want about $50 a board with a 10pc purchase...around $500....no way! I would etch my own before considering that.

I will be sticking with a point to point type of build considering how expensive getting a few boards would likely be.
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If you download their software and keep your board size at 3.8" X 2.5", which seems doable for this design, you can order 2-3 boards for $50-$85.

I'm not sure where you got that price but that's outrageous.
 
#24
Discrete high performance linestage design with 12v rails

kp93300,

The gain is unity, i.e., (1). Its is designed strictly to be used at unity. You could increase the values of R13 and R14 in like magnitude perhaps somewhat, although at a likewise increasing loss of high frequency linearity.

tiefbassuebertr,

I know nothing of Andrea Ciuffoli's MOSFET version and therefore I cannot comment much about it other than you state its idle current is adjustable to 500ma. It seems to me (and perhaps just myself, others have the right to their own opinion) that an idle current of 500ma for a preamp is quite high.

Best Regards,

Rich
 
#25
RBorkowski said:
kp93300,

The gain is unity, i.e., (1). Its is designed strictly to be used at unity. You could increase the values of R13 and R14 in like magnitude perhaps somewhat, although at a likewise increasing loss of high frequency linearity.

tiefbassuebertr,

I know nothing of Andrea Ciuffoli's MOSFET version and therefore I cannot comment much about it other than you state its idle current is adjustable to 500ma. It seems to me (and perhaps just myself, others have the right to their own opinion) that an idle current of 500ma for a preamp is quite high.

Best Regards,

Rich
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That is correct. By the use of supply voltage from only 12V the power loss is 6W - not extrem for a preamp. But one disadvantage you must accept: A low value of undistorted line voltage output (mostly no problem, but in cases, where the power amp section also is a voltage unity gain device not usable.
 
#29
jmillerdoc said:
Been searcing the forums to no avail....lookingfor a high performance linestage that will run off 12v +/- rails that is fairly simple to implement. Please let me knowif you habe a good design/schematic.
Thanks!
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I made a line stage as a headphone amp app. which could be used as a line amp as well. Published in latest issue of Linear Audio magazine. Also, discussed in the headphone amp section. pcb being made.
 
#30
linuxguru said:
Check out PCB Power (India) Ltd. - I have no interest in it, except as a delighted customer. They do prototype quantities at competitive rates using pooled services, but they also have Express and On-Demand services with more finish options, etc.

Welcome to PCBPower.com

You'll have to register and get verified by their customer service before you can place an order, but you can do price calculations based on board dimensions and options without registration. Once registered and verified, almost everything can be transacted using the web interface, including invoices and payments.
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Thanks for that,I was looking for it since long time
 
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