I have been hunting around the net looking for a high quality but neccessarily cheap:-( phono stage.
I am considering a TNT InDiscreet rather than a kit, but a Pass Pearl seems pretty interesting as well. (OK there are lots of others including VSPS, and some others from TNT)
Anyone have experience w/the InDiscreet directly? What about the Pearl?
I am considering a TNT InDiscreet rather than a kit, but a Pass Pearl seems pretty interesting as well. (OK there are lots of others including VSPS, and some others from TNT)
Anyone have experience w/the InDiscreet directly? What about the Pearl?
Hi Nanook,
I don't know much about the TNT phono, I was thinking of building it once. Sometimes it is best to just 'jump in' and build a phono stage just to hear what it sounds like. The Passlabs Pearl Phono is a great stage, well worth considering. Also, there's the ESP P06 op-amp based phono stage, well worth building too. There are a number of phono stages to choose from. It largely depends on how much you want to spend.
I hope this is of some help
All the best.
Brownlow
I don't know much about the TNT phono, I was thinking of building it once. Sometimes it is best to just 'jump in' and build a phono stage just to hear what it sounds like. The Passlabs Pearl Phono is a great stage, well worth considering. Also, there's the ESP P06 op-amp based phono stage, well worth building too. There are a number of phono stages to choose from. It largely depends on how much you want to spend.
I hope this is of some help
All the best.
Brownlow
Looks like a reasonable simple design, but if I were building it, I think I would perhaps want to replace all the tail current sources for the differential pairs and the 10k emitter follower load with current sources. I might build it with current source loads and then compare with resistors, to see what happens...
Just to share, I built this initially as an cheaper alternative to my diy 12AX7 phono stage. Design and fab my own PCB without realizing there is a PCB design provided. Anyway, I did some modifications, changed the transistors from BC109 to a lower noise BJT BC550.
Output coupling from 10uF to a smaller 2.2uF JB capacitor while interstage 0.2uF using parallel 0.1u Vishay MKP1837 vs my 12AX7 uses CD 940C both output and interstage coupling which are way more expensive compared to JB and MKP1837. I don’t see the need to overkill using 10uF to drive my tube preamp which input impedance >100Kohm... power supply, I designed my own using simple LM317/337.
The result...no audible noise apart from slight hums which I can live with.....Summarizing in short the experience, I ended up retired my 12AX7 phono... it makes me want to play more Of my LPs... just amazing. After few weeks listening to this discrete phono, I tried to switch back to my old trusted diy 12AX7.... It only lasted few song play as it sounds dull compared to the new discrete which is more dynamic with mid & high detail and punchy tight bass.
For equalization network caps, I used 1% MKP1837 where available and the smaller ones I used 5% Wima.... before this, I always taught higher quality sound can only be achieved thru tubes....and to add... this is my very first SS gear in my main stereo system... so anyone plan to build, do without hesitation.....
Output coupling from 10uF to a smaller 2.2uF JB capacitor while interstage 0.2uF using parallel 0.1u Vishay MKP1837 vs my 12AX7 uses CD 940C both output and interstage coupling which are way more expensive compared to JB and MKP1837. I don’t see the need to overkill using 10uF to drive my tube preamp which input impedance >100Kohm... power supply, I designed my own using simple LM317/337.
The result...no audible noise apart from slight hums which I can live with.....Summarizing in short the experience, I ended up retired my 12AX7 phono... it makes me want to play more Of my LPs... just amazing. After few weeks listening to this discrete phono, I tried to switch back to my old trusted diy 12AX7.... It only lasted few song play as it sounds dull compared to the new discrete which is more dynamic with mid & high detail and punchy tight bass.
For equalization network caps, I used 1% MKP1837 where available and the smaller ones I used 5% Wima.... before this, I always taught higher quality sound can only be achieved thru tubes....and to add... this is my very first SS gear in my main stereo system... so anyone plan to build, do without hesitation.....
Had a quick look at the TNT InDiscreet circuit and was frankly dissappointed.
The input is a differential pair, presumably to avoid AC coupling the input, but with the unfortunate side-effect of doubling the noise compared to a single transistor input stage.
And secondly it specifies BC109B's, not the superior (and cheaper I think) lower noise BC109C's. Again to reduce noise performance for strange reasons?!
Anyway the BC109C was the go-to low noise transistor in the 1970's, its not the best available these days, but still it can do well if biased correctly:
The input transistors are run at a high 0.27mA level, I think you'll get lower noise at around 50uA level for a MM input.
(For an MC input section you need very low impedance and low voltage-noise parts like the ZTC851, a very different design in fact)
Anyway the many straight-forward NE5534A RIAA circuits out there are much simpler and very performant for noise, RIAA precision, distortion and headroom.
The input is a differential pair, presumably to avoid AC coupling the input, but with the unfortunate side-effect of doubling the noise compared to a single transistor input stage.
And secondly it specifies BC109B's, not the superior (and cheaper I think) lower noise BC109C's. Again to reduce noise performance for strange reasons?!
Anyway the BC109C was the go-to low noise transistor in the 1970's, its not the best available these days, but still it can do well if biased correctly:
The input transistors are run at a high 0.27mA level, I think you'll get lower noise at around 50uA level for a MM input.
(For an MC input section you need very low impedance and low voltage-noise parts like the ZTC851, a very different design in fact)
Anyway the many straight-forward NE5534A RIAA circuits out there are much simpler and very performant for noise, RIAA precision, distortion and headroom.
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Hi,
I built this preamp too, with BC549B instead of BC109 and the original PSU in separate metal box.
For electrolytics I used Nichicon UFW on Preamp board and UKW in PSU, film caps Kemet PPS for RIAA and interstage, and JB for output.
I'm very satisfied with it's detailed sound, it has a lot of gain and dinamics.
I built this preamp too, with BC549B instead of BC109 and the original PSU in separate metal box.
For electrolytics I used Nichicon UFW on Preamp board and UKW in PSU, film caps Kemet PPS for RIAA and interstage, and JB for output.
I'm very satisfied with it's detailed sound, it has a lot of gain and dinamics.
What ever theory of analysis, my actual build (with BC550) doesn’t give audible noise comparing to my tube build...I surprised myself that I like this more than my 12AX7 one.... good transient from Earl Klugh guitar and others too... livelier than tube... which I found 10x better than audiolab 8000A on board phono.
Friend of mine build it for his own use, with decent (no boutique) components, no battery style. Sound is quite good compared to the cost of the project: enough gain, dynamic response, clean sound, not noisy for MM operation. As the builder was using a wooden box with some aluminum foil as electrostatic screen, the second user had problems with EMF, solved by ferrite rings on input cables. Sound wise, performance was comparable with ProJect Phono Box S2 (TNT has more gain than the ProJect, and sounds a bit more transparent - test was done on Technics SL 1200MkII and Ortofon 2M-Bronze MM cartridge).
Hello everybody, I want to ask you it is possible that this preamplifier to run with 6+2 batteries https://www.mega-piles.com/im/VARTA-3LR12-4-5V-6000mAh-HIGH-ENERGY_9.pdf or 3+1 Baltrade.eu - B2B shop ? Many thanks...
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