The Kuartlotron - keantoken's simple error-correction superbuffer

Hi
I transfered BJT to JFET
acting very good on sims...
cheers
:)
 

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Hello everyone!

After a long break for the realization of a phono preamp, I just get back on the Kuartlotron. Circuit boards are ready and it remains to solder the components.

Regard's
 

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Hi Zoran. The Jfet models in SPICE are usually not very accurate and there are some built-in flaws. I'm sure a Jfet version would operate in real life, but probably not like the simulator predicts. Go a ahead and try it if you want, I'll be curious about the results.

Note that in your simulation the only output load is 470k. This is unrealistic. Try 22k or 5k.
 
Some questions.

1: Exactly which board should it swap with?
2: Should I use the same basic layout as that board?
3: What would be a good relay circuit to use?
4: Dual mono PSU, separated regulators or put it all on the same supply?

I'm thinking the power supply will use a virtual ground, no need for a center tapped trafo. The power will be a TL431 shunt regulator. This will be the simplest option and do very well. It does not have to be this way however.
 
Yes Ken, right...
I spot that some values should be adjusted in real circuits. Mostly parts that controlling the currents (Rs). Usually lower values are real, so the initial values of biasing will give lower Io probably. But I will test.
.
I put the 470K at the output of the unit, but real load is at the output connector (upper on the sch), and this is 10K *or more precise (10K parallel with 470K, bit lower than 10K) and about 100pF of cable capacitances.
.
with that fixed values of zener diodes of 6.2V, power supply value should be adjusted for zero V offset @ output
 
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Some questions.

1: Exactly which board should it swap with?
2: Should I use the same basic layout as that board?
3: What would be a good relay circuit to use?
4: Dual mono PSU, separated regulators or put it all on the same supply?

I'm thinking the power supply will use a virtual ground, no need for a center tapped trafo. The power will be a TL431 shunt regulator. This will be the simplest option and do very well. It does not have to be this way however.

4x Kmultipliers? Regulated?

I'd be down for that. How big would it be getting? Maybe a seperate PSU would suffice at that point. Also then the PSU wouldn't matter as much, and people could do batteries if they wanted.

I guess one could then choose between having a dual PSU or feeding the 4x Kmultipliers with a single full bridge. The stuff I like to use wouldn't fit on the same board as DCB1, PSU wise.

Looks like I might be holding off before assembling my sets of these items... got all the parts next to me.
 
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It depends on what the builders think of paying for expensive relays. I will design it to be compatible with the relatively cheap relays that seem to be satisfactory based on many comments. I can add support for compatible more expensive relays if there is desire for it.

Here is a draft of the basic plan in my head. I would say comments are encouraged, but they are in fact mandatory.
 
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Destroyer OS., no one is really suggesting in-line relays, and JC only says he's only _suspicious_ of open relays - as you would have with a mute relay.... And in any case you could just put links in if you did not want them. On the Mezmerize board they are in a separate section for just this purpose. But for many people they are very useful.
 
Destroyer OS., no one is really suggesting in-line relays, and JC only says he's only _suspicious_ of open relays - as you would have with a mute relay.... And in any case you could just put links in if you did not want them. On the Mezmerize board they are in a separate section for just this purpose. But for many people they are very useful.

I wasn't sure where it went. That's just the last thing I saw on relays.
 
I use omishra's power supply which is based on LM317/337. It works quite well. I like the fact that output voltage is adjustable with trim pots.

BTW, Keantoken, I think that this buffer is good enough to deserve a balanced version. It has, as mentioned earlier, displaced the DCB1 (though I'm yet to complete the hot rodded version, which I hope will elevate it to a much higher plane). What say you?:)
 
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Some questions.

1: Exactly which board should it swap with?
2: Should I use the same basic layout as that board?
3: What would be a good relay circuit to use?
4: Dual mono PSU, separated regulators or put it all on the same supply?

I'm thinking the power supply will use a virtual ground, no need for a center tapped trafo. The power will be a TL431 shunt regulator. This will be the simplest option and do very well. It does not have to be this way however.

If you are asking me:

1. It could be interchangeable with DCB1/Mezmerize but it is not really necessary
2. In case of point 1 being true: yes
3. See DCB1/Mezmerize schematic. I attached the muting circuit to this post.
4. IMO stereo board with shared PSU but separate supplies won't break the bank. The no doubt approach.
5. Why virtual GND when center tapped transformers are standard ?
6. Why TL431 when it can be better ? I spotted a 15V Zener diode. We can do better than that and also more compact. SMD ultra low noise regs + cheap 2 x 8V transformer....
7. I don't see much decoupling in the schematic. Doesn't it need decoupling caps ?
8. Volume control is missing. Adding pads for a potentiometer would be nice. Any other volume control could be soldered to those.
9. Both balanced and unbalanced versions could be designed.
10. I would use standard telecom relays when shorting to GND, they have gold plated contacts anyway. A low power mini version would be nice. It is better to short to GND as the contacts would be out of the signal path as opposed to contacts in series with the outputs. Mesmerize first had series contacts but this was changed in later board revisions.

* 2 x 8V transformer would give way more voltage with this load. It has to be tested but with LDO regs I think it will work out OK. A 2 x 9V will work for sure.
 

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Joined 2002
Tamura PL5.0-16-130B is 7.80 $ at Digikey. It could be a lighter type, this one is 5VA. DPC-16-260B10 also seems OK. Some want 120VA types as this is audio but IMO small is beautiful :)

Power draw is 11 mA per channel so 22 mA. Add a dim glowing power LED (2.5 mA) and 2 signal relays for muting and one input chosen. The much liked G6H-2-100-DC12 draw 12 mA at 12V.... So power draw is minimal. Add CRC filtering or CLC filtering for removing RF and/or other garbage. I use common mode coils a lot. They work good.
 
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