Sorry about the basic question.
I heared a statement: Regulate the high voltage making better sound. (Preamp)
there is 2 questions:
1.If it's ture, why the most preamp circuits using C-R-C or C-L-C ripple filiter circuit, not regulate circuit ?
2.How does the sound different?
Thanks for your answer
I heared a statement: Regulate the high voltage making better sound. (Preamp)
there is 2 questions:
1.If it's ture, why the most preamp circuits using C-R-C or C-L-C ripple filiter circuit, not regulate circuit ?
2.How does the sound different?
Thanks for your answer
Proper regulation (note the qualifier!) can be beneficial to preamp circuits that operate at low levels and/or have mediocre power supply rejection. Unlike simple filter circuits, regulators maintain their low source impedance right down to DC and have outstanding line rejection. On the downside, doing a proper low-noise design is not always trivial.
As with everything else.... tradeoffs.
As with everything else.... tradeoffs.
The above is only true for diy projects; most commercial designs use regulators.
It's difficult enough to design a good-sounding low votage regulator
In tube preamp circuits line regulation is not very important and i doubt if low impedance is also that useful. So, traditional regulation virtues are not really required.
What is really important is low ps noise.
And low noise is easy to achieve with a passive CRC or LCL type of filter. Even if you have to use many cascaded filters. Yes, active regulation achieves the same but only by introducing NFB and even worse - solid state devices.
There is of course the old VR type of tube which is quite benign in sonic signature and even die-hard tube lovers seem to accept it.
So, how does regulation sound? It really depends upon the regulator design. Most SS regulators, even topologies which sound acceptable in SS circuits, seem to clash in sonic character with tubed circuits. They often sound sterile, overdamped, flat.
Over the years i've been searching in vain for that elusive regulator circuit, which while being cheap, light and simple to make could replace the piles of chokes and separate power supplies for each stage.
The search is still on.
I made some regulators for line, and phono preamp. My experience is that non feedback regulators sound better.
I prefer BJTs over mosfets as series pass device, and some additional load makes the sound better. For line amplifier with 20mA, I recommend to use resistive load (simple resistor), which results additional 20mA at least.
For very low current, simple zener regulator do the best.
Some insulator filter helps too. 10-100ohms series, and 10-47uF paralell at the output of the regulator makes the sound closer to the fully passive filtering. With this filter I found no difference between the mosfet, and bjt series pass elements.
sajti
I prefer BJTs over mosfets as series pass device, and some additional load makes the sound better. For line amplifier with 20mA, I recommend to use resistive load (simple resistor), which results additional 20mA at least.
For very low current, simple zener regulator do the best.
Some insulator filter helps too. 10-100ohms series, and 10-47uF paralell at the output of the regulator makes the sound closer to the fully passive filtering. With this filter I found no difference between the mosfet, and bjt series pass elements.
sajti
Don't I Just Love That Glow....
Hi,
Yeah....I hear alot of cowboy stories too.....
I have 3 VR tubes per channel in my phono preamp for the moment in a series reg.
All of which are rock stable, they don't oscillate and don't do any of the other nonsense zeners (well most of them anyway) tend to do.
I'm currently considering using a stack of VR tubes as a shunt reg after the series reg but don't hold your breath. It's more work than I thought it to be.
No but they can have tons of it in front of them, you'll only need some resistance between the two.
***Has anyone ever triode a diode for that?***
No big deal with high Z loads such as a preamp.
The shunt cap is only there to prevent the tube from oscillating.
If you're a bit selective on the VR tubes you won't even have to use a shunt cap.
I don't have much hands on experience with the big octal VRs, always used the 7 pinners with no problems whatsoever.
Go through some data manuals, there are a few gems out there for use in preamps.
Even multiple ones in a single bottle for your next X-mass tree...
Cheers,
Hi,
Yeah....I hear alot of cowboy stories too.....
I have 3 VR tubes per channel in my phono preamp for the moment in a series reg.
All of which are rock stable, they don't oscillate and don't do any of the other nonsense zeners (well most of them anyway) tend to do.
I'm currently considering using a stack of VR tubes as a shunt reg after the series reg but don't hold your breath. It's more work than I thought it to be.
No but they can have tons of it in front of them, you'll only need some resistance between the two.
***Has anyone ever triode a diode for that?***
No big deal with high Z loads such as a preamp.
The shunt cap is only there to prevent the tube from oscillating.
If you're a bit selective on the VR tubes you won't even have to use a shunt cap.
I don't have much hands on experience with the big octal VRs, always used the 7 pinners with no problems whatsoever.
Go through some data manuals, there are a few gems out there for use in preamps.
Even multiple ones in a single bottle for your next X-mass tree...
Cheers,
SY said:
I have very little experience with them. A dozen or so years ago I split the supply to the input 12ax7a of my MC240 with a capacitance multiplier, convinced myself it sounded better (as all changes do at first
), and then forgot all about it through the next dozen years of daily use. The circuit consisted of a transistor, resistor and capacitor if I recall correctly. That's why it came to mind in this low-current pre-amp application. I should revisit and properly measure the thing some day.Multiple VR tubes in one envelope?
Do they all have different colors?
Sounds interesting,maybe I'll have to look some up (do you know any of the tube #'s off-hand?),and see if I can find any at the local surplus place,they sound neat!
I may just have a preamp project in mind where they could be put to good use,now that I know they are 'safe' for low-level stuff.
Do they all have different colors?
Sounds interesting,maybe I'll have to look some up (do you know any of the tube #'s off-hand?),and see if I can find any at the local surplus place,they sound neat!
I may just have a preamp project in mind where they could be put to good use,now that I know they are 'safe' for low-level stuff.
Hi,
I use an all tube regulator in my preamp, it gives very low noise and hum, noise level is much lower than what comes from the amplifier circuit itself. The regulator is optimised for low hum and noise but not for good regulation which is of no interest for a tube preamp. VR tubes gives lower noise and better regulation than high voltage zeners and it is no problem to filter out the little noise there is.
For me the choice is easy, I have difficulty to find good arguments for using chokes in a preamp power supply when it is not so difficult to design a voltage regulator that gives lower hum and noise. The trick when designing a regulator I think is to realise what is important, (low hum and noise troughout a wide frequency range) and what is not, (good regulation).
Regards Hans
I use an all tube regulator in my preamp, it gives very low noise and hum, noise level is much lower than what comes from the amplifier circuit itself. The regulator is optimised for low hum and noise but not for good regulation which is of no interest for a tube preamp. VR tubes gives lower noise and better regulation than high voltage zeners and it is no problem to filter out the little noise there is.
For me the choice is easy, I have difficulty to find good arguments for using chokes in a preamp power supply when it is not so difficult to design a voltage regulator that gives lower hum and noise. The trick when designing a regulator I think is to realise what is important, (low hum and noise troughout a wide frequency range) and what is not, (good regulation).
Regards Hans
Zeners produce 2 or 3 times more noise than VR tubes - my ears and my scope told me that.
I am always using VR tubes in my projects (0B2, 0C3, VR150, StR-series a.o.) and the sonic results are always great. Small bypass cap is needed to rejects the small noise (0.068-0.1uF) but it depends of the tube batch - some tubes need the bypass cap, some tubes don't.
And all VR tubes look nice in the dark
I am always using VR tubes in my projects (0B2, 0C3, VR150, StR-series a.o.) and the sonic results are always great. Small bypass cap is needed to rejects the small noise (0.068-0.1uF) but it depends of the tube batch - some tubes need the bypass cap, some tubes don't.
And all VR tubes look nice in the dark
Also look at the spectrum, Zener diodes are good as noise generators as they give an even noise level up to very high frequencies, VR tubes give noise in a more narrow BW, one other problem I have seen with Zeners is the relatively high low frequency noise that is almost non existent in VR tubes, this low frequency noise which is of importance in RIAA amps is a bit difficult to filter out when using zeners.
Regards Hans
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