I never thought of that. Usually only something like 1uF required to shunt battery chemistry noise. The 1uF doing the same function as the secondary function of the one on a regulator. Even a fuse has enough resistance to get the capacitor to form a RC filter. Measurements show this.
Often batteries don't sound as good as you would think. The 1 uF changes that. Polypropylene class X2 a cheap type of impeccable performance. A cheaper Chinese one called Suntan ( ! ) is very good. Rapid UK show them. X2 types to resist flashover have audiophile construction. Very often audiophile types are the same thing sold at ten times the price.
Not sure if you thought I ment laptop batteries? I think laptop chargers (switched power supplies) are generally referred to as laptop bricks, and that is what I'm using.
They are rated 7A 19,5V and have no problem starting with big caps connected, and noise/ripple is pretty ok. DELL or HP, can't remember right now.
EMI seems ok too, compared to some ASUS charger I have that messed with my measurements until I found it to be the cause.
They are rated 7A 19,5V and have no problem starting with big caps connected, and noise/ripple is pretty ok. DELL or HP, can't remember right now.
EMI seems ok too, compared to some ASUS charger I have that messed with my measurements until I found it to be the cause.
No, they are power bricks, same as your laptop bricks but with different plugs to prevent mistakes. The bricks I linked will supply 24V/4A which is 96W and about all you can get as a constant load from a plastic brick power supply without overheating. Peak current can be quite a bit higher but the size of the plastic case and its capacity to dissipate heat limits continuous power to less than maximum ratings.
4A should be plenty enough to power each JLH'69 drawing 2A at idle and give you noticeably more audio power than a 19V supply. I guess if you wait long enough, newer laptops which have 24V supplies will also be obsolete and then you can have free 24V bricks 🙂
4A should be plenty enough to power each JLH'69 drawing 2A at idle and give you noticeably more audio power than a 19V supply. I guess if you wait long enough, newer laptops which have 24V supplies will also be obsolete and then you can have free 24V bricks 🙂
The CF5 common mode choke from LCR is cheap and good. In theory the noise should be diffential mode. My experience is common mode is a problem. Often big smps have common mode chokes. The Meanwell smps does.
As you may know a LM 317 can be made into a class A amplifier. I makes me wonder if a TL431 and power transistor could also. One thing I have not seen is a LM317 SE amplifier used with LM317 current source. LM337 if sinking sourcing question comes up.
As you may know a LM 317 can be made into a class A amplifier. I makes me wonder if a TL431 and power transistor could also. One thing I have not seen is a LM317 SE amplifier used with LM317 current source. LM337 if sinking sourcing question comes up.
Give it a try. Five dollars worth of parts and you've got a 1.4 watt class-A amplifier. Enter it into Nelson Pass's FAOW (First And Only Watt) amplifier collection / friendly competition.
Ibias = 0.5A --> P = I*I*Rload/sqrt(2) = 1.4 continuous RMS watts into 8R
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Ibias = 0.5A --> P = I*I*Rload/sqrt(2) = 1.4 continuous RMS watts into 8R
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A variation is a NE5534. Power Darlington booster and LM317 CCS. If using LD1084 We might get ≥ 2 amps. Whilst 5534 is one of many it has compensation terminals that almost certainly would be used. The 5534 is high output current. If a complimentary feedback pair used in place of the Darlington linearity should be excellent. The design could have low current mode for listening at lower volume. The voltage swing slightly greater also.
My TV amp is an optimistic 1.7: watts. As long as bass isn't below 20 Hz it uses that power well. When it was 5 Hz current limiting happened. Mostly program quality is the question. 2 watts is fine for many things. My big speakers are well over 100 dB at 2 watts. You can feel ripple in the fingers with them.
Thanks for the information.
My TV amp is an optimistic 1.7: watts. As long as bass isn't below 20 Hz it uses that power well. When it was 5 Hz current limiting happened. Mostly program quality is the question. 2 watts is fine for many things. My big speakers are well over 100 dB at 2 watts. You can feel ripple in the fingers with them.
Thanks for the information.
I have been listening a lot to the PNP JLH 69 from Zerozone, and I really like it! I had a friend over to get a second opinion, and he agreed with me too. Going back and forth between amps, I always like this one the best. Improved highs and lows compared to the standard 69 with MJ15003, without any drawbacks as far as I can hear.
To me it seems the circuit benefits from newer (faster) transistors, and the floating ground with switched supply seems to be a good compromise too, if one can accept the LF swings at startup. No fatigue or headaches after long listening sessions, really smooth to my ears, but yet fairly controlled and detailed.
Of course, this makes me think that maybe even more can be had with other transistors etc, so I ordered some ebay kits with supposed 5200 transistors, and some with TIP41. The plan is to try them as is, and try them with some genuine toshibas I have etc, to see(hear) what the result is.
Been thinking about what to try next when it comes to amps. Something that I like even more, and maybe something that would give some more power, and maybe handle lower impedance loads better.
I've looked a bit on the dartzeel clone amps, only because the original amp seems like the ultimate contradiction when it comes to measured performance vs subjective impressions. (measures like hell and sounds like heaven? 🙂 )
Curious about Hiraga amps too. Feel free to suggest the ultimate amp 😉
Ok before moving on, I should definitely try higher supply voltage on the JLH's to increase power as I'm only using 19,5V bricks now, but for improved performance to lower impedance I'm not sure. The double outputs don't seem to do it. All measurements I have done indicate significantly increased distortion at 4ohm, and sadly many 8ohm speakers are not far from 4 in reality. Maybe some transistor combinations in the JLH will work wonders..
To me it seems the circuit benefits from newer (faster) transistors, and the floating ground with switched supply seems to be a good compromise too, if one can accept the LF swings at startup. No fatigue or headaches after long listening sessions, really smooth to my ears, but yet fairly controlled and detailed.
Of course, this makes me think that maybe even more can be had with other transistors etc, so I ordered some ebay kits with supposed 5200 transistors, and some with TIP41. The plan is to try them as is, and try them with some genuine toshibas I have etc, to see(hear) what the result is.
Been thinking about what to try next when it comes to amps. Something that I like even more, and maybe something that would give some more power, and maybe handle lower impedance loads better.
I've looked a bit on the dartzeel clone amps, only because the original amp seems like the ultimate contradiction when it comes to measured performance vs subjective impressions. (measures like hell and sounds like heaven? 🙂 )
Curious about Hiraga amps too. Feel free to suggest the ultimate amp 😉
Ok before moving on, I should definitely try higher supply voltage on the JLH's to increase power as I'm only using 19,5V bricks now, but for improved performance to lower impedance I'm not sure. The double outputs don't seem to do it. All measurements I have done indicate significantly increased distortion at 4ohm, and sadly many 8ohm speakers are not far from 4 in reality. Maybe some transistor combinations in the JLH will work wonders..
You probably would have liked the old Hitachi mosfet design. The Hypex also isn't bad if a lot of trouble is taken over the power supply.
It has always been in my mind that an amplifier with 6 watts class A power has solved the problems. 100 watts class AB after that.
The NAD3020 has remarkable current delivery. Like a bumble bee it doesn't make sense. It also is very low on listening fatigue. I think because they were ubiquitous no one has understood how remarkable they are. I think hi fi choice got 192 watts 1R transient from a 3020. 2 watts from a 170 watt Sony. I heard that Sony and it was gutless. Too much protection to get a big 8R wattage.
I understand scientice have discovered that bumble bees can fly and it wasn't just conjecture. That only having 30% of the energy required can be forgotten.
It has always been in my mind that an amplifier with 6 watts class A power has solved the problems. 100 watts class AB after that.
The NAD3020 has remarkable current delivery. Like a bumble bee it doesn't make sense. It also is very low on listening fatigue. I think because they were ubiquitous no one has understood how remarkable they are. I think hi fi choice got 192 watts 1R transient from a 3020. 2 watts from a 170 watt Sony. I heard that Sony and it was gutless. Too much protection to get a big 8R wattage.
I understand scientice have discovered that bumble bees can fly and it wasn't just conjecture. That only having 30% of the energy required can be forgotten.
I think the pnp version being best could be that PNP power transistors have higher current gain. Often they are more fragile. The current limiting stops that being a weekness. The gain isn't vastly more, enough maybe to help.
I didn't expect the bumblebee story to have wings. It's great when science admits it struggles to understand. I absolutely love bumblebees. They lived in my house with instructions to leave them alone to my family. None of us were stung and the bees sort of said hello briefly and went to their place. It was an honour to share. The house was 1600s, they lived in the metre thick walls.
I think I have built at least 50 diy amp and kit with almost all the diagrams produced on this earth, including at least 10 of jlh (69,96,2005;pnp,mosfet).
for me, it's the best quality / price ratio for everyday listening pleasure.
I found that mine are all different and are very sensitive to the choice of components and power supply.
for my ears, the simplest jlh 69 connected to L100 century is a real pleasure.
for this one, I copied the Hiraga 20w power supply.
I tried the laptop power supply brick, I did not like it, I only use it to make presets.
I also think that we are very far from having gone around this diagram
As I have said before I am convinced very fast transistors also have higher current gain. I really doubt we hear the speed. THD should be lower.
There is one unfortunate aspect of class A. It has a high continuous current use. This means noise from the power supply needs to be dealt with. That becomes the weakest part of the sound. Julian Vereker of Naim Audio agreed that his amplifiers were up to 80% power supply and 20% amplifier. Thus it would be a signal modulates power supply. Valve amplifiers are high voltage low current. That helps. SE valve designs have greater problems and need better power supplies. Given that the technical problems are understood se valve designs have the most open and layered sound. One I built is six watts 1% thd one watt 0.2% thd. It had the least sense of distortion of any amplifier I have heard at a sensible price. The PSU I had to use was a fet capacitance multiplier. It took a few attempts to become reliable. 500 V starting voltage. -66dB hum without multiplier -88 dB with. For such a simple design that's excellent and very fast. The fet less than £1. It was at 8 volts loss 70 mA. Insulated T0220FP making it simple to deal with. It produces a small amount of second harmonic distortion showing it to be part of the amplifier. It has virtually no negative feedback. Not even cathode type and 50% positive feedback. The same type as JLH. JLH uses about 90%. The starting point with the design was 6% thd. Unfortunately Danbury transformers I used no longer exist that made the design possible. It was a quirk of the transformer that made it work. That is 83% triode ultra linear feedback. This measures like triode with better voltage gain. Both Triode. and ultra linear are forms of negative feedback. As triodes have internal negative feedback purists consider them to still have the concept of no negative feedback.
There is one unfortunate aspect of class A. It has a high continuous current use. This means noise from the power supply needs to be dealt with. That becomes the weakest part of the sound. Julian Vereker of Naim Audio agreed that his amplifiers were up to 80% power supply and 20% amplifier. Thus it would be a signal modulates power supply. Valve amplifiers are high voltage low current. That helps. SE valve designs have greater problems and need better power supplies. Given that the technical problems are understood se valve designs have the most open and layered sound. One I built is six watts 1% thd one watt 0.2% thd. It had the least sense of distortion of any amplifier I have heard at a sensible price. The PSU I had to use was a fet capacitance multiplier. It took a few attempts to become reliable. 500 V starting voltage. -66dB hum without multiplier -88 dB with. For such a simple design that's excellent and very fast. The fet less than £1. It was at 8 volts loss 70 mA. Insulated T0220FP making it simple to deal with. It produces a small amount of second harmonic distortion showing it to be part of the amplifier. It has virtually no negative feedback. Not even cathode type and 50% positive feedback. The same type as JLH. JLH uses about 90%. The starting point with the design was 6% thd. Unfortunately Danbury transformers I used no longer exist that made the design possible. It was a quirk of the transformer that made it work. That is 83% triode ultra linear feedback. This measures like triode with better voltage gain. Both Triode. and ultra linear are forms of negative feedback. As triodes have internal negative feedback purists consider them to still have the concept of no negative feedback.
One needs to be very careful when making such statements, as the clueless (and biased) run away with them make inferences that are not valid.
Specifically, the inference that the behaviour of a triode (as a three port device) and the behaviour of a classic differential-amplifier-plus-gain-and-pole feedback circuit (e.g. an opamp) have anything in common beyond the output conditions affecting overall circuit behaviour verges on the disingenuous.
One could equally say that a battery has "internal feedback" and be just as literally true.
The internal feedback of a triode is overcome by additional grids in a pentode valve. From this a curve in someways similar to a transistor is seen in a pentode. A pentode is a transition resistance device . If the G2 grid of a pentode is strapped to the anode something reasonably similar to a true triode can be arrived at. However that is one of a few ways. Alex Kitic shows an amplifier design in a series called RH . RH 34 using ECC81 and EL34. The ECC81 is used as it has for a triode a high anode impedance. This allows local feedback to the true pentode. The ECC81 used as a V to I converter. The strange thing is the circuit looks mostly conventional. Measuring shows it isn't. Kitic often gets heated because people refuse. to build the exact circuit. For example if an ECC82 is used the whole way the circuit works changes. Measurements are not very different except the output impedance of the EL34 goes up which isn't helpful. His amplifier uses transistor inspired principles. The nearest transistor pentode type device to me is the EF86. The Kitic designs do not use a cathode bypass capacitor to the biasing resistor of the ECC81 as that ruins the local feedback. The measurements don't change much except the EL34 output impedance rises. That's a bad trade off. Critics of Kitic say this method was seen on 1938 RCA designs for 807 Beam Tetrode. That's a fairly weak critism. In fact RCA show a variation of it in a Dynaco like design. The Dynaco circuit is a standard RCA circuit for 7199 pentode triode. It is one of the great landmark designs. 7199 is a television valve with hum shielding. The Dynaco is an ultra linear design as Hafler held one patent for that and he was Dynaco. Cathode ultra linear being another and probably better way. Strange that Hafler got that patent as Blumlein wrote about it in 1935.
My point about 83% ultra linear triode end is reference books would not recommend it. It measures just like a triode with greater voltage gain. That's quite handy. Ultra linear is turbocharging for valves. I will regret saying that. It is as useful as but not greatly like.
RH series is good reading as is The Valve Wizard and Tube Cad. The latter often does transistor designs.
My point about 83% ultra linear triode end is reference books would not recommend it. It measures just like a triode with greater voltage gain. That's quite handy. Ultra linear is turbocharging for valves. I will regret saying that. It is as useful as but not greatly like.
RH series is good reading as is The Valve Wizard and Tube Cad. The latter often does transistor designs.
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But then someone would build one with those awful old leaky bumblebee capacitors!
Talking of how things can fly, most elementary textbooks on aerodynamics explain how aircraft wings work completely wrong. http://www3.eng.cam.ac.uk/outreach/Project-resources/Wind-turbine/howwingswork.pdf