#26 pre amp - Page 154

Original Burnedfingers · 1st February 2012, 10:47 AM

Accessories for DIY audio projects

Two Terminal Constant Current Source

These products were developed based on the Supertex DN2540N5 and IXYS IXTP01N100D depletion mode MOSFETs to enable constant current operation of tube circuits without having to worry about a source of bias. They are very simple and easy to integrate into existing designs. Use current sources to provide excellent balance in "long-tail" pair differential circuits or to obtain highly linear constant current triode operation as a plate load. Add a heat sink kit for operation at higher levels of power dissipation. Three versions are offered: an economical basic current source with very good performance, a cascode current source for improved measured performance and a slight sonic improvement, and a compact cascode current source that can be used to replace resistors for easy upgrading to constant current operation. These kits feature current adjustability over a wide range (2.5mA to 100mA) and space for a fixed resistor to replace the variable resistor once the “correct” current has been determined. The minimum operating voltage is 4VDC + 1/2 peak-to-peak AC signal amplitude and the voltage rating maximum is 1000VDC.

Current source kit
Cascode current source kit
Compact Cascode current source kit

Basic Current Source Kit (up to 1.5 watts) $8
Cascode Current Source Kit (up to 1.5 watts) $12
Small Heat Sink Kit (up to 4 watts) $3
Large Heat Sink Kit (up to 7 watts) $3.50
Compact Current Source Kit (up to 3 watts w/included heat sink) $14
Large Cascode Current Source Kit (up to 7 watts w/included heat sink) $18

Which kits should I purchase?

vgeorge · 1st February 2012, 10:50 AM

What do you need a CCS for?

euro21 · 1st February 2012, 11:21 AM

If use CCS as anode load, (B+=220V, operating point 159V, 6.2mA) static dissipation only 370mW. Max. dissipation 570mW.

Original Burnedfingers · 2nd February 2012, 10:36 AM

I was going to use a CCS in each power supply prior to the voltage regulator tubes I will be using. I plan a choke before the plate. I just wanted to know which unit to purchase because I would like something on a pre made PC board so I don't have to make something up. Since I am making two power supplies one for each mono block line stage channel. I have no experience with these CCS's and for that matter I have never used one in anything and would like to purchase the correct one the first time around.

vgeorge · 2nd February 2012, 01:49 PM

I would recommend a cascoded dn2540.
Although a point to point one is not so difficult to make. You can copy Salas SSHV2 CCS part easily.

euro21 · 3rd February 2012, 09:05 PM

SSHV2 for type 26.

Simplistic Mosfet HV Shunt Regs

Original Burnedfingers · 4th February 2012, 10:21 AM

I ordered two cascode kits from K&K Audio.

Original Burnedfingers · 5th February 2012, 10:22 AM

I think I remember mentioning that I was going to use VR tubes for shunt regulation. I know that I received several comments to the fact that they are noisy. Well I have a thread about rectifier tubes sounding different and there is a post a reference to the Ammnity Raven and something else. Anyway there is a comment on VR tubes which I will quote here

A deluxe feature, which was easy to add, is the Voltage Regulator (VR) tube shunt-regulation for the driver. I wanted to drop 270 volts, so why not regulate at the same time? The noise of VR tubes is only 1mV of very smooth broadband noise, while the more common Zener diodes have 3 to 5mV of spectrally nonflat noise, occasional LF bumps and pops from "popcorn" noise, problems with temperature coefficients, and a huge amount of grossly nonlinear capacitance. Zener diodes need a lot of filtering and additional circuitry to isolate the problems. By contrast, VR tubes need no additional circuitry at all - just keep them away from capacitive loads.

So why are VR tubes frowned upon so much and why wouldn't they be a good element to use in a #26 line stage?

Original Burnedfingers · 5th February 2012, 10:34 AM

Ok, so if I use a power supply with some ripple and I run it thru a cascoded DN2450 CCS and then a VR shunt regulator stage I should come out with a ripple of 1mv or so. At this point would I not be good to go for a choke loaded #26. Would I be better off to ditch the choke and go thru another CCS and then the #26's plate?

There is an article on "Minimun Reactance Power Supply" at Chapter 5

It says I could have 100 volts of ripple and as long as the stayed above the 220v the CCS would reject all the ripple. They are saying they want to maintain 200 volts on the output.

So if I used a CCS before my VR tubes and a CCS to feed the plate of the #26 I would have 0 ripple at the plate of the #26? Is this correct?

regal · 5th February 2012, 11:39 AM

I'm not sure use two CCS's this way, they will fight one another with tempeature dift and oscillate unless the first one is much bigger than the sond?

The problem wih the VR tubes is hiss, you can filter it out with a big eletrolytic in paralell but then you have a big electrolytic in the signal path and reportedly a cheap cap sounds like a cheap cap and a BG sounds like a BG, defeats the purpose of a shunt, also the output impedance of the vr tubes is high for a powersupply. See the epc audio electric avenue project.

For low noise regulation the sshv is tough to beat, there is a new group buy for version 2 forming.

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1st February 2012, 10:47 AM	#1531
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Accessories for DIY audio projects Two Terminal Constant Current Source These products were developed based on the Supertex DN2540N5 and IXYS IXTP01N100D depletion mode MOSFETs to enable constant current operation of tube circuits without having to worry about a source of bias. They are very simple and easy to integrate into existing designs. Use current sources to provide excellent balance in "long-tail" pair differential circuits or to obtain highly linear constant current triode operation as a plate load. Add a heat sink kit for operation at higher levels of power dissipation. Three versions are offered: an economical basic current source with very good performance, a cascode current source for improved measured performance and a slight sonic improvement, and a compact cascode current source that can be used to replace resistors for easy upgrading to constant current operation. These kits feature current adjustability over a wide range (2.5mA to 100mA) and space for a fixed resistor to replace the variable resistor once the “correct” current has been determined. The minimum operating voltage is 4VDC + 1/2 peak-to-peak AC signal amplitude and the voltage rating maximum is 1000VDC. Current source kit Cascode current source kit Compact Cascode current source kit Basic Current Source Kit (up to 1.5 watts) $8 Cascode Current Source Kit (up to 1.5 watts) $12 Small Heat Sink Kit (up to 4 watts) $3 Large Heat Sink Kit (up to 7 watts) $3.50 Compact Current Source Kit (up to 3 watts w/included heat sink) $14 Large Cascode Current Source Kit (up to 7 watts w/included heat sink) $18 Which kits should I purchase?

1st February 2012, 10:50 AM	#1532
vgeorge diyAudio Member Join Date: Mar 2004 Location: poros island	What do you need a CCS for?

2nd February 2012, 10:36 AM	#1534
Original Burnedfingers diyAudio Member Join Date: Nov 2002	I was going to use a CCS in each power supply prior to the voltage regulator tubes I will be using. I plan a choke before the plate. I just wanted to know which unit to purchase because I would like something on a pre made PC board so I don't have to make something up. Since I am making two power supplies one for each mono block line stage channel. I have no experience with these CCS's and for that matter I have never used one in anything and would like to purchase the correct one the first time around.

2nd February 2012, 01:49 PM	#1535
vgeorge diyAudio Member Join Date: Mar 2004 Location: poros island	I would recommend a cascoded dn2540. Although a point to point one is not so difficult to make. You can copy Salas SSHV2 CCS part easily.

4th February 2012, 10:21 AM	#1537
Original Burnedfingers diyAudio Member Join Date: Nov 2002	I ordered two cascode kits from K&K Audio.

5th February 2012, 10:22 AM	#1538
Original Burnedfingers diyAudio Member Join Date: Nov 2002	I think I remember mentioning that I was going to use VR tubes for shunt regulation. I know that I received several comments to the fact that they are noisy. Well I have a thread about rectifier tubes sounding different and there is a post a reference to the Ammnity Raven and something else. Anyway there is a comment on VR tubes which I will quote here A deluxe feature, which was easy to add, is the Voltage Regulator (VR) tube shunt-regulation for the driver. I wanted to drop 270 volts, so why not regulate at the same time? The noise of VR tubes is only 1mV of very smooth broadband noise, while the more common Zener diodes have 3 to 5mV of spectrally nonflat noise, occasional LF bumps and pops from "popcorn" noise, problems with temperature coefficients, and a huge amount of grossly nonlinear capacitance. Zener diodes need a lot of filtering and additional circuitry to isolate the problems. By contrast, VR tubes need no additional circuitry at all - just keep them away from capacitive loads. So why are VR tubes frowned upon so much and why wouldn't they be a good element to use in a #26 line stage?

5th February 2012, 10:34 AM	#1539
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Ok, so if I use a power supply with some ripple and I run it thru a cascoded DN2450 CCS and then a VR shunt regulator stage I should come out with a ripple of 1mv or so. At this point would I not be good to go for a choke loaded #26. Would I be better off to ditch the choke and go thru another CCS and then the #26's plate? There is an article on "Minimun Reactance Power Supply" at Chapter 5 It says I could have 100 volts of ripple and as long as the stayed above the 220v the CCS would reject all the ripple. They are saying they want to maintain 200 volts on the output. So if I used a CCS before my VR tubes and a CCS to feed the plate of the #26 I would have 0 ripple at the plate of the #26? Is this correct?

5th February 2012, 11:39 AM	#1540
regal diyAudio Member Join Date: Jan 2004 Location: MD	I'm not sure use two CCS's this way, they will fight one another with tempeature dift and oscillate unless the first one is much bigger than the sond? The problem wih the VR tubes is hiss, you can filter it out with a big eletrolytic in paralell but then you have a big electrolytic in the signal path and reportedly a cheap cap sounds like a cheap cap and a BG sounds like a BG, defeats the purpose of a shunt, also the output impedance of the vr tubes is high for a powersupply. See the epc audio electric avenue project. For low noise regulation the sshv is tough to beat, there is a new group buy for version 2 forming.

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