Hi Chokesrule,
No problems I know what it is like when one is learning. I would also suggest that you read the sticky threads on safety and online learning for newbies. Also if you can get a copy of Morgan Jones ‘Valve amplifiers’ it will serves as a good reference.
In relation to your reasoning, it all seems right. The operating point of 100V @ 20mA does lie right on the -2V grid voltage. So you will need a B+ of 200V and at least 30-40mA. Having a transformer with higher current rating helps, because your B+ voltage will drop (sag) as current draw increases. If you search the forums on 6n6p operating points, some have suggested 12-15mA. Let’s use 13 mA, so from the curves 13mA, 100V Vg = -2.8V. R=V/I 2.8/.013 = 215 ohms. You can use a 220 ohm resistor.
You can rate the resistors for 0.5 to 1 watt, always good to over specify so they run cooler. I’ve found a quality wire wound to sound good, but you can always use metal film etc.
Regarding the operating points, I haven’t experimented much with the 6n6p, what you can do is try different points and see how you go. Yes you can use this method for any triode in SRPP. Voltage output dacs usually give a higher output so you don’t need a tube with a high amplification factor (mu). However, current output dacs have their current converted to a voltage usually by an i/v resistor with the result being a very low output voltage, hence the need of a tube with high amplification i.e. the use of a tube like the 6n2p (mu = 100) for the tda1541.
Regarding grid leak, have a look at the links below, SY offers some good advice in the second:
Tube Terminology for Dummies
http://www.diyaudio.com/forums/tubes-valves/136327-value-grid-leak-resistor.html
http://archive.ampage.org/threads/0/ampdiy/003476/Re_How_about_this-1.html
Also be sure to be careful when testing and constructing with high voltages, have a bleeder resistor (say 100K) across the power supply caps (B+ to ground) and check they are drained before touching.
Rich
No problems I know what it is like when one is learning. I would also suggest that you read the sticky threads on safety and online learning for newbies. Also if you can get a copy of Morgan Jones ‘Valve amplifiers’ it will serves as a good reference.
In relation to your reasoning, it all seems right. The operating point of 100V @ 20mA does lie right on the -2V grid voltage. So you will need a B+ of 200V and at least 30-40mA. Having a transformer with higher current rating helps, because your B+ voltage will drop (sag) as current draw increases. If you search the forums on 6n6p operating points, some have suggested 12-15mA. Let’s use 13 mA, so from the curves 13mA, 100V Vg = -2.8V. R=V/I 2.8/.013 = 215 ohms. You can use a 220 ohm resistor.
You can rate the resistors for 0.5 to 1 watt, always good to over specify so they run cooler. I’ve found a quality wire wound to sound good, but you can always use metal film etc.
Regarding the operating points, I haven’t experimented much with the 6n6p, what you can do is try different points and see how you go. Yes you can use this method for any triode in SRPP. Voltage output dacs usually give a higher output so you don’t need a tube with a high amplification factor (mu). However, current output dacs have their current converted to a voltage usually by an i/v resistor with the result being a very low output voltage, hence the need of a tube with high amplification i.e. the use of a tube like the 6n2p (mu = 100) for the tda1541.
Regarding grid leak, have a look at the links below, SY offers some good advice in the second:
Tube Terminology for Dummies
http://www.diyaudio.com/forums/tubes-valves/136327-value-grid-leak-resistor.html
http://archive.ampage.org/threads/0/ampdiy/003476/Re_How_about_this-1.html
Also be sure to be careful when testing and constructing with high voltages, have a bleeder resistor (say 100K) across the power supply caps (B+ to ground) and check they are drained before touching.
Rich
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Thanks Richard,
I hadn't see that one. However reading
http://www.fortunecity.com/rivendell/xentar/1179/theory/vasfda/vasfda.html
on Thosten's web pages I see a SRPP I/V stage that is almost identical to Lampizator circuits if you ignore the filtering. i will probably start by trying one of Thoesten's circuits.
I hadn't see that one. However reading
http://www.fortunecity.com/rivendell/xentar/1179/theory/vasfda/vasfda.html
on Thosten's web pages I see a SRPP I/V stage that is almost identical to Lampizator circuits if you ignore the filtering. i will probably start by trying one of Thoesten's circuits.
Hi Chris,
I'm using the 10m45s, on little boards from DIYHifiSupply, as plate loads on my tube I/V stage. I've tried a few tubes and circuits, it's currently a simple 5687 anode follower. 6N6P was also good. DAC is a PCM63.
Rod
Thanks Rod.
Just to state where I am coming from and what I want to achieve. I have built various DACs and output stages, modified CD players over the years and am pretty confused as to what works best tho I believe the output stage is a major player. So far I have built (not all for myself!):
Philips CD880, TAD1541A S1 NONOS with Pedja Rogic AD844 I/V stage
USB DACs with both TDA1543 and TDA1545 using DIYParadise SS I/V stages
Philips CD630 TDA1541A NONOS with Fetishizator output stage (see Lampizator website)
Matantz CD80 TDA1541A S1 NONOS with Lampizator output stage
EBay AD1865 NONOS board with Lampizator output stage
All sound good to me to varying degrees but I always come back to my CD880 with the Pedja Rogic stage as a favorite.
Comparrisons are not that easy as some are CD players and some stand alone DACS so sources are different. Tho the CD880 vs CD80 is quite valid - almost identical players originally.
I built the AD1865 with Lampizator stage for a friend and I have my own which I am about to build. I intend trying a couple of SS or op amp stages and a couple of tube stages for use with my AD1865 board such that I am able to make more valid comparrisons and come to some conclusions around what DAC output stages work best for me.
Just to state where I am coming from and what I want to achieve. I have built various DACs and output stages, modified CD players over the years and am pretty confused as to what works best tho I believe the output stage is a major player. So far I have built (not all for myself!):
Philips CD880, TAD1541A S1 NONOS with Pedja Rogic AD844 I/V stage
USB DACs with both TDA1543 and TDA1545 using DIYParadise SS I/V stages
Philips CD630 TDA1541A NONOS with Fetishizator output stage (see Lampizator website)
Matantz CD80 TDA1541A S1 NONOS with Lampizator output stage
EBay AD1865 NONOS board with Lampizator output stage
All sound good to me to varying degrees but I always come back to my CD880 with the Pedja Rogic stage as a favorite.
Comparrisons are not that easy as some are CD players and some stand alone DACS so sources are different. Tho the CD880 vs CD80 is quite valid - almost identical players originally.
I built the AD1865 with Lampizator stage for a friend and I have my own which I am about to build. I intend trying a couple of SS or op amp stages and a couple of tube stages for use with my AD1865 board such that I am able to make more valid comparrisons and come to some conclusions around what DAC output stages work best for me.
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Chris,
I also have an ebay AD1865 board that I use with only a resistor as i/v, no active stage, and it has just enough gain for me. It sounds better than the PCM63 (Rotel 991) with the tube stage. Next I'd like to try SS to have a taste of all the different flavours.
I got some good ideas from Mr Lampizator, like the 6N6P, but I really don't understand why he says you need a high mu tube for I out DAC's. If your amp has enough gain you don't. He recommends the 6N2P, a 12AX7 near -equivalent, in SRPP. I tried that and it sucked
Rod
I also have an ebay AD1865 board that I use with only a resistor as i/v, no active stage, and it has just enough gain for me. It sounds better than the PCM63 (Rotel 991) with the tube stage. Next I'd like to try SS to have a taste of all the different flavours.
I got some good ideas from Mr Lampizator, like the 6N6P, but I really don't understand why he says you need a high mu tube for I out DAC's. If your amp has enough gain you don't. He recommends the 6N2P, a 12AX7 near -equivalent, in SRPP. I tried that and it sucked
Rod
Rod,
Is that the same AD1865 board Lampizator uses? The one I did for a friend used the 6N2P stage, my friend really likes it in his system (best DAC yet he says) but we still prefered my CD880/AD844 in my system.
I was planning on trying the FET I/V stage the board comes with but replacing the electrilytic output caps with some PIO. I will also have a go with the straight I/V resistor as you suggested - my system has tons of gain. Later will try some of the stages I mentioned earlier starting with DIYParadise FET I/V and the Fetishizator as I have thses alredy built.
BTW, presume yuou are using the SPDIF input on the board? What digital source?
Cheers
Is that the same AD1865 board Lampizator uses? The one I did for a friend used the 6N2P stage, my friend really likes it in his system (best DAC yet he says) but we still prefered my CD880/AD844 in my system.
I was planning on trying the FET I/V stage the board comes with but replacing the electrilytic output caps with some PIO. I will also have a go with the straight I/V resistor as you suggested - my system has tons of gain. Later will try some of the stages I mentioned earlier starting with DIYParadise FET I/V and the Fetishizator as I have thses alredy built.
BTW, presume yuou are using the SPDIF input on the board? What digital source?
Cheers
Yeah, it's the same DAC Mr L wrote about. My source is the SPDIF from my Rotel 991 CD player which was top of the line about 10 years ago and is built like it. Very impressive for the money.
I've been using it with the op-amp output stage replaced by the 6n6p stage for a while now. Sounds quite a bit better than the original. Using the AD1865 board with no active output straight into my amp is another step forwards. I can't imagine that the on-board SS output stage will be an improvement but I'd like to try it anyway.
But back to the 6n2p - the 12 AX7 can't drive any sort of load without significant distortion. I'm no expert but I really see how this tube, or it's like,can be appropriate in a DAC output stage. I'm happy for someone to explain, though!
I've been using it with the op-amp output stage replaced by the 6n6p stage for a while now. Sounds quite a bit better than the original. Using the AD1865 board with no active output straight into my amp is another step forwards. I can't imagine that the on-board SS output stage will be an improvement but I'd like to try it anyway.
But back to the 6n2p - the 12 AX7 can't drive any sort of load without significant distortion. I'm no expert but I really see how this tube, or it's like,can be appropriate in a DAC output stage. I'm happy for someone to explain, though!
There is a good discussion of that in this thread:
http://www.diyaudio.com/forums/tubes-valves/133180-12ax7-srpp-dac-output.html
Thanks for the help Rich
Sorry for the late reply The info you have given me has really helped construct my srpp.Thanks for the time answering what to you must seem very basic questions. Its built, but just like when I made my mark one, it takes me a few days to pluck up the courage to actually switch on lol...
Sorry for the late reply The info you have given me has really helped construct my srpp.Thanks for the time answering what to you must seem very basic questions. Its built, but just like when I made my mark one, it takes me a few days to pluck up the courage to actually switch on lol...
Hi Proitex,
Any transformer with a secondary of 120 to 160V AC will be fine. Having a 6.3V secondary tap for the heater will be beneficial. Local electronic surplus shops are a cheap source. Another cheap alternative would be to use an isolation transformer, or you can always purchase directly from Lukasz:
transformers-price
Cheers,
Rich
Any transformer with a secondary of 120 to 160V AC will be fine. Having a 6.3V secondary tap for the heater will be beneficial. Local electronic surplus shops are a cheap source. Another cheap alternative would be to use an isolation transformer, or you can always purchase directly from Lukasz:
transformers-price
Cheers,
Rich
Anyone who is in the UK, and wants to try the Lampizator, can order the one i had custom made from Airlink Transformers.
9284 : 37 va transformer
9284 : 37 va transformer
sums do not equal observations
Hi, the lampi mark2 is up and running. I have each triode powered from its own bridge rectified transformer, giving 160v ac secondary. This gives me 223 volts dc . I am sending this thru a CLCLCRC filter. My chokes have a resistance of 700R ohms. So I calculated:
1) I need a volatage drop of 23 volts so the upper anodes get 200v the lower then working at the recommended 100volts
2) volts (drop)=I (set by the cathode resistor) * R (resistance to the anode)
3)R=V/I so r=23/0.01=2k3ohms
4) so the resistor needed to get 200volts is 2300-(700*2)=900R ohms. The 1400 ohms is from the resistance in the two in series chokes
5) i set up, turn on and see from my meters 190 volts , 0.013 amps
6 ) gradually step down the resistor in the rc filter and end up with just the chokes/capacitors and NO resistor(in the power filter) still giving me 190volts
7) It sounds great but is not performing to the figures.
8 ) I remove a choke and get 200volts, 13 ma......it is hard to say about the audable difference, maybe the two chokes is more dynamic.
So what is going on here????What have I missed????
If you are new to electronics can I just point out DONOT measure voltage on your mulimeter then turn the switch to the current setting. YOU MUST break the anode power cable and link the meter in "SERIES"!!!!!!
I had wired my ammeter from the last filter capacitor to the upper anode. Both valves get the same values. Is this a suitable metering point?
I had run my valve heaters from dc and suffered from a large voltage drift using furkas's CRC filter. I get a steady suppy by adding a extra RC and uping the uf of the first capacitor to 22,000 uf, and using 10,000uf thereafter. Do not do his " link the heaters in series of 12.6volts dc!!!!" it doesnot work. I tried with 6 valves they all ran at different voltages. So it may be just as well to run of 6.3 volts ac directly. Something to consider when ordering a custom transformer. Any way now his shop is open :buy your kit from Fikus. He has put all the effort into that site to get people switched on so I think the least we can do is use his products, he is cheap anyway.
Hi, the lampi mark2 is up and running. I have each triode powered from its own bridge rectified transformer, giving 160v ac secondary. This gives me 223 volts dc . I am sending this thru a CLCLCRC filter. My chokes have a resistance of 700R ohms. So I calculated:
1) I need a volatage drop of 23 volts so the upper anodes get 200v the lower then working at the recommended 100volts
2) volts (drop)=I (set by the cathode resistor) * R (resistance to the anode)
3)R=V/I so r=23/0.01=2k3ohms
4) so the resistor needed to get 200volts is 2300-(700*2)=900R ohms. The 1400 ohms is from the resistance in the two in series chokes
5) i set up, turn on and see from my meters 190 volts , 0.013 amps
6 ) gradually step down the resistor in the rc filter and end up with just the chokes/capacitors and NO resistor(in the power filter) still giving me 190volts
7) It sounds great but is not performing to the figures.
8 ) I remove a choke and get 200volts, 13 ma......it is hard to say about the audable difference, maybe the two chokes is more dynamic.
So what is going on here????What have I missed????
If you are new to electronics can I just point out DONOT measure voltage on your mulimeter then turn the switch to the current setting. YOU MUST break the anode power cable and link the meter in "SERIES"!!!!!!
I had wired my ammeter from the last filter capacitor to the upper anode. Both valves get the same values. Is this a suitable metering point?
I had run my valve heaters from dc and suffered from a large voltage drift using furkas's CRC filter. I get a steady suppy by adding a extra RC and uping the uf of the first capacitor to 22,000 uf, and using 10,000uf thereafter. Do not do his " link the heaters in series of 12.6volts dc!!!!" it doesnot work. I tried with 6 valves they all ran at different voltages. So it may be just as well to run of 6.3 volts ac directly. Something to consider when ordering a custom transformer. Any way now his shop is open :buy your kit from Fikus. He has put all the effort into that site to get people switched on so I think the least we can do is use his products, he is cheap anyway.
I've shown you #17: A differential White cathode follower circuit.
That among many other amazing feats, also just happens to self
regulate its own line stage voltage... Quite Broskiesque in ability
to cancel crud that don't belong, though he has yet to respond
to my requests to help get theory of operation explained to the
masses.
Either CRC or LC is fine, you won't need tons of excess filterage.
Can feed with anything from 80 to ??? at least 250 I would think.
Common mode rejection range maybe not so wide down 80V end.
Your supply is way overkill for the purpose, but would not need
any changes, and certainly does not need further upgrades!
Any who dismiss DWCF circuit as too complicated to bother with?
Think again on the complexity of power supply that is eliminated.
Plain Jane cathode follwers will always have 1/(Mu-1) power supply
noise measured at the cathode. DWCF does not suffer this problem.
Therefore all lampizator technology: Is like soOOo 5min ago...
+75VDC added to heaters will block hum from crossing to cathodes.
This is probably at least as good as DC heaters. Can do both is you
want to be obsessive... Just need a 75V stack of Zeniers to GND,
and a pull up resistor to B+ at heater center tap. No caps necessary.
Zenier white noise is less than 6VAC hum, and both blocked for same
reason.
Only wish DWCF could have voltage gain? Driven differentially by
DAC, gain is unity at best. Single ended, its gain is less than 0.5.
Yet current gain is substantial, and not a thing to be sneezed at.
Can drive much lower impedance than normal cathode follower.
With LTP up front for voltage gain, this could be the differential
input equivalent of an Aikido.
That among many other amazing feats, also just happens to self
regulate its own line stage voltage... Quite Broskiesque in ability
to cancel crud that don't belong, though he has yet to respond
to my requests to help get theory of operation explained to the
masses.
Either CRC or LC is fine, you won't need tons of excess filterage.
Can feed with anything from 80 to ??? at least 250 I would think.
Common mode rejection range maybe not so wide down 80V end.
Your supply is way overkill for the purpose, but would not need
any changes, and certainly does not need further upgrades!
Any who dismiss DWCF circuit as too complicated to bother with?
Think again on the complexity of power supply that is eliminated.
Plain Jane cathode follwers will always have 1/(Mu-1) power supply
noise measured at the cathode. DWCF does not suffer this problem.
Therefore all lampizator technology: Is like soOOo 5min ago...
+75VDC added to heaters will block hum from crossing to cathodes.
This is probably at least as good as DC heaters. Can do both is you
want to be obsessive... Just need a 75V stack of Zeniers to GND,
and a pull up resistor to B+ at heater center tap. No caps necessary.
Zenier white noise is less than 6VAC hum, and both blocked for same
reason.
Only wish DWCF could have voltage gain? Driven differentially by
DAC, gain is unity at best. Single ended, its gain is less than 0.5.
Yet current gain is substantial, and not a thing to be sneezed at.
Can drive much lower impedance than normal cathode follower.
With LTP up front for voltage gain, this could be the differential
input equivalent of an Aikido.
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