DIY Elektor PreConsonant

[vs music]

Hi Victor. I aim to attempt to make a power supply using your circuit soon. I wanted to double confirm the values though. Are all your "," intended as decimal places or are some thousands separators? e.g. "FU1 - 0,5A" is clear to me it's 0.5A, and "C3 - 0,1" must be 0.1uf, however "C1 - 3300,0 x50v" is that 3300.0uF. as in 3300uF, or 3300,0uf / 33000uf?

Thanks!

Hello , Damien !
3300,0 х 50v  is 3300 microfarads . You can use a different nominal value - 1000 or 2200 microfarads .

[damiena]

Hello , Damien !
3300,0 х 50v  is 3300 microfarads . You can use a different nominal value - 1000 or 2200 microfarads .

Great, thank you Victor!

I will then presume this is the same for the other values - ie in the 2nd board there is a C3 - 470,0 35v ..... so I should read this as 470.0uF or 470 microfarads....

[vs music]

Great, thank you Victor!

I will then presume this is the same for the other values - ie in the 2nd board there is a C3 - 470,0 35v ..... so I should read this as 470.0uF or 470 microfarads....

Yes , of course - 470 microfarads

[MartinX]

Hello!

I am a long time lurker on this forum this is my first post.

I have followed this thread with great interest and now finally managed to build my version of the preconsonant preamp, since I have worked for an electronics producing company for 20+ years I have no fear of surface mount components, they are just a reality you have to deal with, and nowadays SMD components have higher availability than through hole. So i made the preamp surface mount for the most part, it looks like this.



BC550C and BC560C are replaced with the surface mount equivalents BC850C and BC860C, they are made by Nexperia the heir of Philips, hopfully as good as the old Philips BC transistors, as input transistor i have 2SA1312-BL, now sadly not in production any more but i have a stash. I have chosen to add a TL431 based shunt regulator on the board it should be possible to feed this board pretty unfiltered supply voltage. The capacitors in the RIAA filter is 1% ceramic NP0 types and since i hand solder this they are 1206 or 1210 size, the resistors are 0204 mini melf, 1% metal film. The electrolytics in the signal path are Nichicon KL low leakage type.

This could have been made much more compact but now it is pretty easy to hand solder this and very close distances is not always an advantage. The board is 76x36mm Here is the complete schematic.



The board is one channel only, if you want the boards can be stacked on top of each other if there is height available in the box.

I have not listened to this yet, but soon I will connect this to my Lenco L85-IC.

[stratokaster83]

Hello!

I am a long time lurker on this forum this is my first post.

I have followed this thread with great interest and now finally managed to build my version of the preconsonant preamp, since I have worked for an electronics producing company for 20+ years I have no fear of surface mount components, they are just a reality you have to deal with, and nowadays SMD components have higher availability than through hole. So i made the preamp surface mount for the most part, it looks like this.



BC550C and BC560C are replaced with the surface mount equivalents BC850C and BC860C, they are made by Nexperia the heir of Philips, hopfully as good as the old Philips BC transistors, as input transistor i have 2SA1312-BL, now sadly not in production any more but i have a stash. I have chosen to add a TL431 based shunt regulator on the board it should be possible to feed this board pretty unfiltered supply voltage. The capacitors in the RIAA filter is 1% ceramic NP0 types and since i hand solder this they are 1206 or 1210 size, the resistors are 0204 mini melf, 1% metal film. The electrolytics in the signal path are Nichicon KL low leakage type.

This could have been made much more compact but now it is pretty easy to hand solder this and very close distances is not always an advantage. The board is 76x36mm Here is the complete schematic.



The board is one channel only, if you want the boards can be stacked on top of each other if there is height available in the box.

I have not listened to this yet, but soon I will connect this to my Lenco L85-IC.

Great job!

If I remember correctly, BC860C and 850C have worse noise figures than their through-hole counterparts.

[vs music]

Hello!

I am a long time lurker on this forum this is my first post.

I have followed this thread with great interest and now finally managed to build my version of the preconsonant preamp, since I have worked for an electronics producing company for 20+ years I have no fear of surface mount components, they are just a reality you have to deal with, and nowadays SMD components have higher availability than through hole. So i made the preamp surface mount for the most part, it looks like this.



BC550C and BC560C are replaced with the surface mount equivalents BC850C and BC860C, they are made by Nexperia the heir of Philips, hopfully as good as the old Philips BC transistors, as input transistor i have 2SA1312-BL, now sadly not in production any more but i have a stash. I have chosen to add a TL431 based shunt regulator on the board it should be possible to feed this board pretty unfiltered supply voltage. The capacitors in the RIAA filter is 1% ceramic NP0 types and since i hand solder this they are 1206 or 1210 size, the resistors are 0204 mini melf, 1% metal film. The electrolytics in the signal path are Nichicon KL low leakage type.

This could have been made much more compact but now it is pretty easy to hand solder this and very close distances is not always an advantage. The board is 76x36mm Here is the complete schematic.



The board is one channel only, if you want the boards can be stacked on top of each other if there is height available in the box.

I have not listened to this yet, but soon I will connect this to my Lenco L85-IC.

Beautiful work !

[MartinX]

Great job!

If I remember correctly, BC860C and 850C have worse noise figures than their through-hole counterparts.

That depends on the data sheets you compare, if I take Philips data sheet of BC550C from 1982 it is pretty much identical to the 2004 NXP BC850C when it comes to noise, the data given is not that detailed so who knows. looking at old data sheets 1996 Motorola claims the best noise performance of the ones I seen.

[vs music]

The noise of any of the simple phonopreamps will always be lower than the surface noise of even a new record . This has been tested many times .
 This fact makes it possible to produce phono-preamps on all sorts of exotic transistors ( on germanium transistors , for example ) .
And this is very useful for us .

[MartinX]

It´s alive! My intension is to have the boards as part of a preamp, since this is the first part of it I build there is no preamp to put them in, so I mounted the boards in a temporary box i had, it housed an electronic ignition system once, hence the extra holes. It´s just the record player the preconsonant boards, powered from my antique lab power supply and a headphone amplifier, sounds promising, pretty clean sound, a bit of hum at max volume with the pickup lifted, but there is no real thought through grounding in this setup. The Lenco L85 IC did not come with a grounded mains cord in 1975 I may have to look at that.

[stratokaster83]

I want to power my PreConsonant from a 24V AC wallwart, however I measured its output and it can get a bit higher depending on the time of day. Initially I wanted to use a simple 3-pin voltage regulator but the rectified DC would be a bit too high to the absolute maximum rating for my comfort...

That's why I designed a simple 24V regulator rated for 500mA max current (which is about 50x what the whole PreConsonant would ever consume).

TIP122 is quite capable of operating at many times that output current, however the resistors etc. are all calculated based on the 500mA value.

[MartinX]

Fairly conventional but C3 looks like an odd thing connected like that, I have not simulated this but is it not a risk C3 will be reverse polarised during start up?

I would have connected C3 to ground from the junction of R32 and R42, then maybe another 10µF across R21 and R22 to increase ripple rejection.

[stratokaster83]

Fairly conventional but C3 looks like an odd thing connected like that, I have not simulated this but is it not a risk C3 will be reverse polarised during start up?

I would have connected C3 to ground from the junction of R32 and R42, then maybe another 10µF across R21 and R22 to increase ripple rejection.

I have not simulated this as well, but this method of bootstrapping the collector resistor of Q1 is recommended in "Electronic Circuit Design and Application" by Gift and Maundy. This capacitor could be fairly small as long as its reactance at the ripple frequency (which in this case would be 100 Hz) is lower than the value of R41 + R42, so it could be a 4.7uF bipolar electrolyte, for example.

[PCB-AUDIO]

Description of the Preconsonant scheme in the journal Elektor 1978 .

if interest , i can supply the original pcb or a complete kit of this phono preamplifier .
the pcb is like original design.
tks

[PCB-AUDIO]

pcb available ...original design

[PCB-AUDIO]