Build it and try it. The bumble bee has only 30 % the power it needs to fly therefore it doesn't exist, scientists are still having trouble with this. I did full power tests at 30 kHz and it was still chugging along.
The graphs can not lie. The thing is this. Ripple is 0.5V. Dynamic range to deal with that is 6 V as a pessimistic figure. Short the 10 K as I did to prove how well it works. Graphs can not lie. If you like the ripple lives in the drain as long as the dynamic range is not exceeded. If a transistor we might get it to work at 2V.
You can do what I did . Loose 20 V then come back a bit until ripple appears. It is a current amp and works like a crude LM317. The critical voltage is 3 V to switch the device on. Would be more like 5 V if wanting 2 amps.
The one criticism is it will respond to the music. It slightly increases the second harmonic distortion. Hum is musically nasty ( harsh ). Second harmonic is nice. Mostly MOS FET's are resistors at these low frequencies in terms of sound given.
Shunt regulators are a reverse bumble bee, said to fly yet don't. Generally they stop working at very low frequencies ( 10 MHz) . They often oscillate. Mostly the output capacitor does the work as with a series regulator. Some think they sound better. I have my doubts. One shunt design I saw went to 1000 entries and they still were tweaking it. When I asked if it could go to 100 MHz I was told I clearly didn't understand shunt regulators. I suspect my question said I did?
Resistor auto bias sometimes makes the valve work better towards the end of it's life.
Valve Wizard is an excellent source of info.
The Valve Wizard -Single Ended
See last part.
The Brook Amplifier & Sliding-Bias SE Power Amplifier
BTW.
Just in case people don't understand the RH amps here are a few explanations. As Ross Walker of Quad said to me " there are only three ways to connect a transistor and one of those it wrong" . Equally applies to triode valves. RH design uses so called plate to plate feedback. That is mildly incorrect as feeding a signal to the ECC81 anode plate is not a way of controlling it. Instead the Rp ( anode resistance ) is high for ECC81 as long as the cathode is fed from a single resistor with no bypass capacitor, a diode is not quite the same. This allows negative feedback between output valve and it's own g1 to go mostly unimpeded. Thus the RH design is what might be called a Super Triode compound pair. The ECC81 as V to I converter and output valve a I to V converter. Kitic claimed an Rp of 900 ohms in what seems still to be a Pentode/Beam tetrode, lower than triode I think ? If you doubt the action measure at all points with one valve out in some tests ( see the output leap up). Then repeat with ECC82. The difference is not subtle. ECC82 in this set up is mostly a conventional voltage amp to voltage amp. As it is swings and roundabouts the difference is not that great.
To my dismay it is a mild variation of the triode type curve.
If a pentode we might play with all the grids if EL34. An unusual one is to take out g1 and feed signal to g2. This is a low Mu triode. Strapped to anode g2 is the usual. The Kitic transistor way is very rare. Shunt feedback pentodes like EF 86 make good phono stages. I don't think I ever saw a shunt feedback output pentode in a recent amp. Poor Kitic was called a plagiarist and his design attributed to Schade. Not really so.
One design I didn't show is the EF184 to replace the ECC81. On paper this should answer all criticisms and has the potential to have greater Rp. High Rp triode is almost a contradiction. By carefully setting g2 it should give a better gain and distortion result. For fun you could try shunt feedback to it and share the same coupling capacitor thus keeping degradation to a minimum. EF184 is more or less a ECC81 if in triode. I would call that with an EL34 a Super Linear pair in the style of Ultra Linear output stage compromise. To be clear the pentode is a great asset and not the triode as often thought. When the two are combined an ideal curve can result. Two triodes do produce a low distortion result. A third one often needs shunt feedback if the distortion trend isn't to go to high. Two have anti-phase cancellation which can mean less distortion than the single elements . If fed as a suspension bridge curve the anti-phases are mirror image from stage to stage when anode feeds the next g1.
Pentodes are not well liked as modern speakers are not designed to suit them. The triode has low Rp and even without feedback does a moderately good job of matching the load. If pentodes are in feedback amps one doesn't really win. Careful UL is a better way to go. Careful UL is rare. Dynaco A70 perhaps works? UL without loop feedback is very good , that seems to stop UL ringing on square-waves.
http://www.kaponk.com/~yanyong/ETF06TS.pdf
Just in case people don't understand the RH amps here are a few explanations. As Ross Walker of Quad said to me " there are only three ways to connect a transistor and one of those it wrong" . Equally applies to triode valves. RH design uses so called plate to plate feedback. That is mildly incorrect as feeding a signal to the ECC81 anode plate is not a way of controlling it. Instead the Rp ( anode resistance ) is high for ECC81 as long as the cathode is fed from a single resistor with no bypass capacitor, a diode is not quite the same. This allows negative feedback between output valve and it's own g1 to go mostly unimpeded. Thus the RH design is what might be called a Super Triode compound pair. The ECC81 as V to I converter and output valve a I to V converter. Kitic claimed an Rp of 900 ohms in what seems still to be a Pentode/Beam tetrode, lower than triode I think ? If you doubt the action measure at all points with one valve out in some tests ( see the output leap up). Then repeat with ECC82. The difference is not subtle. ECC82 in this set up is mostly a conventional voltage amp to voltage amp. As it is swings and roundabouts the difference is not that great.
To my dismay it is a mild variation of the triode type curve.
If a pentode we might play with all the grids if EL34. An unusual one is to take out g1 and feed signal to g2. This is a low Mu triode. Strapped to anode g2 is the usual. The Kitic transistor way is very rare. Shunt feedback pentodes like EF 86 make good phono stages. I don't think I ever saw a shunt feedback output pentode in a recent amp. Poor Kitic was called a plagiarist and his design attributed to Schade. Not really so.
One design I didn't show is the EF184 to replace the ECC81. On paper this should answer all criticisms and has the potential to have greater Rp. High Rp triode is almost a contradiction. By carefully setting g2 it should give a better gain and distortion result. For fun you could try shunt feedback to it and share the same coupling capacitor thus keeping degradation to a minimum. EF184 is more or less a ECC81 if in triode. I would call that with an EL34 a Super Linear pair in the style of Ultra Linear output stage compromise. To be clear the pentode is a great asset and not the triode as often thought. When the two are combined an ideal curve can result. Two triodes do produce a low distortion result. A third one often needs shunt feedback if the distortion trend isn't to go to high. Two have anti-phase cancellation which can mean less distortion than the single elements . If fed as a suspension bridge curve the anti-phases are mirror image from stage to stage when anode feeds the next g1.
Pentodes are not well liked as modern speakers are not designed to suit them. The triode has low Rp and even without feedback does a moderately good job of matching the load. If pentodes are in feedback amps one doesn't really win. Careful UL is a better way to go. Careful UL is rare. Dynaco A70 perhaps works? UL without loop feedback is very good , that seems to stop UL ringing on square-waves.
http://www.kaponk.com/~yanyong/ETF06TS.pdf
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The thing you missed in your analysis Nigel is that a ECC81 has a variable impedance with signal. Since the ECC81 forms one of the legs of the feedback network it results in variable feedback with signal which is guaranteed to generate higher distortion which is not readily detected with a static test signal.
The claimed measurements are largely bogus and when people have tested the RH designs in real life implementations the distortion is significantly higher and rises with increasing input signal.
All these problems are addressed by substituting a EF184 in pentode mode. An EF86 is a poor candidate since it hasn't got enough standing current to push the low impedance feedback node. I would opt for a pentode capable of at least 10mA of standing current and preferably more.
Shoog
The claimed measurements are largely bogus and when people have tested the RH designs in real life implementations the distortion is significantly higher and rises with increasing input signal.
All these problems are addressed by substituting a EF184 in pentode mode. An EF86 is a poor candidate since it hasn't got enough standing current to push the low impedance feedback node. I would opt for a pentode capable of at least 10mA of standing current and preferably more.
Shoog
This is how it stands now..
Switch positions..
The UL position now has no RH feedback so,
Position 1 is RH with 2X100K for 7025/83/82/12AX7 etc
Position 2 is U/L with no RH feedback running all tubes..
Position 3 is RH with 100K for ECC81/12AT7
Cathode F/B and + CCS with diode bias for driver..it seems to work well at the moment..more playing to do..some 22K Tantalums on order for the input resistors and a Silmic 2 cap for the cathode FB just to test..
1K fitted across output for family plug and play protection.
Regards
M. Gregg
Switch positions..
The UL position now has no RH feedback so,
Position 1 is RH with 2X100K for 7025/83/82/12AX7 etc
Position 2 is U/L with no RH feedback running all tubes..
Position 3 is RH with 100K for ECC81/12AT7
Cathode F/B and + CCS with diode bias for driver..it seems to work well at the moment..more playing to do..some 22K Tantalums on order for the input resistors and a Silmic 2 cap for the cathode FB just to test..
1K fitted across output for family plug and play protection.
Regards
M. Gregg
Attachments
Sorry my computer played up . This was the reply.
That's a good way of seeing it. I was speaking for the designer. I got to the same thinking by a different route. I did use 10 mA ( can be 40 mA ) as eventually I will be driving a 211 valve. 620 mV in for 8Vrms out 8R. The funny graph is Quad ESL63 via a microphone ( Stereophile). The amp was for driving them. Rather better than the 300B amp used as comparison I would say ( 6 x 300B pairs tested ). Difference being far more resolute presentation with strong bass. More open also. Not sure I like 300B. This is the chap with the 211 stock pile.
I did look at the RH at all wattages. Didn't see anything to note. I guess the swings and roundabouts stops the miracles from happening. Michale Koster's amp is too brave for me. Looks to be ideal.
Someone said about the series regulator being high Z out. The beauty with SE class A amps is what you see is what you get. There is a minute change in distortion which is about all I saw. The output resistance of the source is fairly low as that is the basis of a source follower amplifier , lower still as it is only <100mA. A CLC Pi filter will be very high were it not for the final C. If the series regulator is at fault hanging a nice big cap the other side should help. Effectively it is an active substitute for a choke. Note how the output looks like a choke.
That's a good way of seeing it. I was speaking for the designer. I got to the same thinking by a different route. I did use 10 mA ( can be 40 mA ) as eventually I will be driving a 211 valve. 620 mV in for 8Vrms out 8R. The funny graph is Quad ESL63 via a microphone ( Stereophile). The amp was for driving them. Rather better than the 300B amp used as comparison I would say ( 6 x 300B pairs tested ). Difference being far more resolute presentation with strong bass. More open also. Not sure I like 300B. This is the chap with the 211 stock pile.
I did look at the RH at all wattages. Didn't see anything to note. I guess the swings and roundabouts stops the miracles from happening. Michale Koster's amp is too brave for me. Looks to be ideal.
Someone said about the series regulator being high Z out. The beauty with SE class A amps is what you see is what you get. There is a minute change in distortion which is about all I saw. The output resistance of the source is fairly low as that is the basis of a source follower amplifier , lower still as it is only <100mA. A CLC Pi filter will be very high were it not for the final C. If the series regulator is at fault hanging a nice big cap the other side should help. Effectively it is an active substitute for a choke. Note how the output looks like a choke.
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I would never be a fan of zero feedback SE amps since the bass is always going to be the Achilles heal of any implementation. It has always struck me that the magic of SE is really the absence of bass and treble extension. Plate to plate feedback is a very benign form of feedback as it get the bass back without introducing lots of phase shift along the way. All my valve amps use lots of plate to plate but they all use pentode drivers and they are all PP bare one spud I just built.
Most people are afraid of large caps in valve amps. Once there is a choke in the supply there is no limit to the amount of capacitance you can put after the choke - even when using valve rectifiers. It takes a good regulator to match the performance of a big cap with sensible bypassing.
Shoog
Most people are afraid of large caps in valve amps. Once there is a choke in the supply there is no limit to the amount of capacitance you can put after the choke - even when using valve rectifiers. It takes a good regulator to match the performance of a big cap with sensible bypassing.
Shoog
Here from memory is how the double current source and sink were made. Values slightly a shot in the dark as this is a less than text book way to do it. All for a reason. The reason being to keep the g2 supply of the pentode quiet. The BD139 is being run hard and needs the metal chassis to cool it. A good quality insulating washer required. Gain is the question more than speed as even 6 MHz class A is very fast , BD139-16 is very fast. I did use a bunch of MPSA92 each with it's own emitter resistor ( 50 MHz). There was a very small advantage.
The double LED is an attempt to beat LM317. The Early effect (I presume) makes more distortion if not. As that would be second harmonic you might choose to recalculate for one LED. My pentode needs to swing 60V rms so you might have to lower the voltage via the 8K2 ( make higher).
If bipolar curves are studied they are the best current amps we can have, so no reason to doubt them. The MOS FET has very high speed as it's advantage.
As said not text book and needs checking for each one built. Text books avoid anything that needs adjustment. If you separate the base supplies no need to make it so tweaky. Myself I like to as any extra power used is more heat and buzz.
This was not used in the amp I presented to my friend. He is old school and wouldn't like it. It gave me benchmarks . It gave half the distortion and retained distortion curve. Effectively as if using 700 V HT to the petode without any risk that might bring.
I did some tests of valve amps with feedback . I found that a good amp maintains it's distortion spectrum when feedback used . 12 dB seems to be when it should be abandoned in favour of modern amps. A Quad 303 has distortion of this type at - 80dB. And it sounds very good.
If a different spectrum appears as soon as feedback is applied I would suggest the amp is not the best it can be. I was blaming the output transformer at first. I then found it not to be true. The ideal amp seems to have only second harmonic up to the point where distortion begins to rise. Then a suspension bridge curve where 5 th harmonic is better than - 70dB at full power . If the distortion does not fall at lets say 1 watt that seems not to matter if it retains a musical curve( exponential). I say the former as a pentode + triode will probably do this without being asked. If as I got the second harmonic is 0.2% (1 watt) is can be said to be like black on TV. Black by comparison even though grey. Black being zero. 0.2% through Quad 63's will be about 0.3% for the complete system . KEF LS50 is 0.8% itself and is state of the art excellent. Suddenly the man with the SE amp is out shining the gits who moan at - 100 dB distortion from a competing amp. I was once told the Hitachi amp I use to be a joke. No one on the planet now or ever should be able to hear that. Then these guys use speakers with 5 % THD to confirm their faith!
If the damping factor of an amp was 3 in the 1950's , by experiment the speaker needed no additional damping. In the 1980's 16 was thought to be very OK. An SE amp might more or less satisfy that with 0 to 12 dB feedback.
If you look at the sine waves I gave they look zero distortion. This seems to be as the harmonics fall on a natural curve. In my day job I see many curves from other things with the same THD. They look obliviously distorted. I will make the observation that I don't think I ever read. If it fools the eye it might fool the ear? The supposed valve sine wave is rounded bottom and more pointy top.
A good valve amp is a box of crayons says my friend John. I can not agree. When a good design a fluidity of sound with no obvious distortion. My Hitachi clone MOS FET amp sounds almost exactly like the friend with the 300B's amp except the Hitachi is louder. That was especially so when the special modern dull emission Kron 300B was used. Mr Kron said he couldn't give them away, he was sad as it was a genuine attempt at better. The Hitachi needs an Audio Precision analyzer to see the distortion. The 303 is bronze medal position.
My Eminence 12 Lta drivers needs high damping factor if I use them full range ( 98dB per watt) . If not they shout. The are in open baffle so the bass is by EQ and the SE defect is of zero importance or slightly helpful. Quad 63's will work fine on 8 watts and are actually loud. The damping as far as I know is unimportant. What is important is that the full 8 watts is real usable power. The 12Lta have superb voice quality so shouting is not their natural way on behaving. I have been talking for about 30 years about these two things. Now I have done it. Conjecture right and laziness maximum.
One thing 1950's OB taught me. 90% of what we do is because we put the speaker in a prison. The nightmare bass is suddenly the real bass we hear in real life. Damping and all that nonsense is exactly that if the right drive units. I use a 2 x 4 foot baffle and + 16 dB 30 Hz. Being a PA unit it will be OK with massive EQ . Conversely the damping factor seems important at 2kHz. Text books seem not to know this unless compression drivers that actually likes negative impedance. No other speaker seems to. 1 watt is very loud and + 16 dB at 30 Hz is possible ( 6.3 watts ).
If a different spectrum appears as soon as feedback is applied I would suggest the amp is not the best it can be. I was blaming the output transformer at first. I then found it not to be true. The ideal amp seems to have only second harmonic up to the point where distortion begins to rise. Then a suspension bridge curve where 5 th harmonic is better than - 70dB at full power . If the distortion does not fall at lets say 1 watt that seems not to matter if it retains a musical curve( exponential). I say the former as a pentode + triode will probably do this without being asked. If as I got the second harmonic is 0.2% (1 watt) is can be said to be like black on TV. Black by comparison even though grey. Black being zero. 0.2% through Quad 63's will be about 0.3% for the complete system . KEF LS50 is 0.8% itself and is state of the art excellent. Suddenly the man with the SE amp is out shining the gits who moan at - 100 dB distortion from a competing amp. I was once told the Hitachi amp I use to be a joke. No one on the planet now or ever should be able to hear that. Then these guys use speakers with 5 % THD to confirm their faith!
If the damping factor of an amp was 3 in the 1950's , by experiment the speaker needed no additional damping. In the 1980's 16 was thought to be very OK. An SE amp might more or less satisfy that with 0 to 12 dB feedback.
If you look at the sine waves I gave they look zero distortion. This seems to be as the harmonics fall on a natural curve. In my day job I see many curves from other things with the same THD. They look obliviously distorted. I will make the observation that I don't think I ever read. If it fools the eye it might fool the ear? The supposed valve sine wave is rounded bottom and more pointy top.
A good valve amp is a box of crayons says my friend John. I can not agree. When a good design a fluidity of sound with no obvious distortion. My Hitachi clone MOS FET amp sounds almost exactly like the friend with the 300B's amp except the Hitachi is louder. That was especially so when the special modern dull emission Kron 300B was used. Mr Kron said he couldn't give them away, he was sad as it was a genuine attempt at better. The Hitachi needs an Audio Precision analyzer to see the distortion. The 303 is bronze medal position.
My Eminence 12 Lta drivers needs high damping factor if I use them full range ( 98dB per watt) . If not they shout. The are in open baffle so the bass is by EQ and the SE defect is of zero importance or slightly helpful. Quad 63's will work fine on 8 watts and are actually loud. The damping as far as I know is unimportant. What is important is that the full 8 watts is real usable power. The 12Lta have superb voice quality so shouting is not their natural way on behaving. I have been talking for about 30 years about these two things. Now I have done it. Conjecture right and laziness maximum.
One thing 1950's OB taught me. 90% of what we do is because we put the speaker in a prison. The nightmare bass is suddenly the real bass we hear in real life. Damping and all that nonsense is exactly that if the right drive units. I use a 2 x 4 foot baffle and + 16 dB 30 Hz. Being a PA unit it will be OK with massive EQ . Conversely the damping factor seems important at 2kHz. Text books seem not to know this unless compression drivers that actually likes negative impedance. No other speaker seems to. 1 watt is very loud and + 16 dB at 30 Hz is possible ( 6.3 watts ).
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I recently built the Le Monstre and am finding it to be as pleasing to the ear as any of my valve amps - but with significantly betterbass extension and control. Effortless is how I describe it.
I cannot agree with you on the Quad 303, my dad had it and I always felt it had that classic sloppy British sound of the 1980's.
I have satisfied myself that a simple and elegant SS amp can sound as good as the best valve amps. What you lose as the feedback rises is naturalness and micro detail. Its easier to keep the feedback down in valve amps so that is I believe why they tend to score over most SS designs. All of this becomes critically important when you use speakers with over 100db/w sensitivity on open baffles - its just remarkable how detailed this setup can sound at even loud sound levels.
Shoog
I cannot agree with you on the Quad 303, my dad had it and I always felt it had that classic sloppy British sound of the 1980's.
I have satisfied myself that a simple and elegant SS amp can sound as good as the best valve amps. What you lose as the feedback rises is naturalness and micro detail. Its easier to keep the feedback down in valve amps so that is I believe why they tend to score over most SS designs. All of this becomes critically important when you use speakers with over 100db/w sensitivity on open baffles - its just remarkable how detailed this setup can sound at even loud sound levels.
Shoog
If you can find a 303 use it with high end speakers , it can shine. I use one with Magneplanar SGMa . To say people look upset is to say the least when they hear them. All of my friends are from high end and have spent a fortune. It is a sound better than 90% heard at shows. It is also very open and bright with killer bass. It will play 1970's TV OK and often does. The resistive nature and OB means they love each other. 4 ohms pure resistance more or less. People say I am lucky. Forgot who said with hard work and practice his luck was getting better?
As I said you might be listening to prisoners. I have had the amp for 23 years and it has been to hell and back with me more than once. It was my kitchen amp. Over the years I realized it was my system that was wrong . The 405 and 2/22 not things I care to own.
As I said you might be listening to prisoners. I have had the amp for 23 years and it has been to hell and back with me more than once. It was my kitchen amp. Over the years I realized it was my system that was wrong . The 405 and 2/22 not things I care to own.
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Its interesting,
Beauty is in the eye of the beholder.
I used to frequent HIFI events in London many moons ago, and I can say that some of the equipment was very expensive. However the sound was a surprise. Having listened to the Ongaku I was not impressed and preferred the Gaku-on. I often find that listening to some equipment can sound like the difference between a two way speaker and a full range set up.
Its also interesting to listen to things from the past that have a sound "tailored" to the likes and what sells well in that generation..I remember saying to a band do you want to sell records or play music..It would be nice if the two went together however If people don't like what your playing you won't make the big time.
Of course amps drive speakers and the speakers drive ears..Having said all of that I have auditioned tube equipment that was not so good and SS that just blew you away. Its interesting to put a quad system side by side with a meridian system and have a listen. Krell is another example..
HIFI often reminds me of perfume... the bottle looks great!
Regards
M. Gregg
Beauty is in the eye of the beholder.
I used to frequent HIFI events in London many moons ago, and I can say that some of the equipment was very expensive. However the sound was a surprise. Having listened to the Ongaku I was not impressed and preferred the Gaku-on. I often find that listening to some equipment can sound like the difference between a two way speaker and a full range set up.
Its also interesting to listen to things from the past that have a sound "tailored" to the likes and what sells well in that generation..I remember saying to a band do you want to sell records or play music..It would be nice if the two went together however If people don't like what your playing you won't make the big time.
Of course amps drive speakers and the speakers drive ears..Having said all of that I have auditioned tube equipment that was not so good and SS that just blew you away. Its interesting to put a quad system side by side with a meridian system and have a listen. Krell is another example..
HIFI often reminds me of perfume...
the bottle looks great!Regards
M. Gregg
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Ongaku is not quite as good as the Danbury amplifier using my audio memory. Mr Kondo I knew and have eaten meals with him. Extremely nice man. Terry O'Sullivan was with him just before he died( Loricraft).
I have begged to meet Mr Hiraga as I have read his stuff since the 1980's. My friend Martina does know him but never introduced us. He said about Coral 777EX PU being the best sounding having exponential distortion circa 1980.
The Pye Mozart is said to be the origin of the Ongaku. I did do a Danbury with the secondary in the EL 34 cathode . It worked rather well as long as phase is correct. Said to be the better way. Don't think I have drawings of that.
I have begged to meet Mr Hiraga as I have read his stuff since the 1980's. My friend Martina does know him but never introduced us. He said about Coral 777EX PU being the best sounding having exponential distortion circa 1980.
The Pye Mozart is said to be the origin of the Ongaku. I did do a Danbury with the secondary in the EL 34 cathode . It worked rather well as long as phase is correct. Said to be the better way. Don't think I have drawings of that.
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it could be the overly complex Quad 33 which was degrading the sound.
As a matter of historic interest I have just refoamed a pair of Tannoy 15" golds for a friend. If you like the classic English sound then these have it in spades. I personally wouldn't take them over my vintage german field coil FR speakers in OB. Horrible - simply horrible.
Shoog
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Quad 303 too complex? No. Class AB yes. AB is like MP3 which I admire also. Wrong but not horribly wrong. If the 303 outputs were just Exicon 10N/P16 that would be perfect. Even though the output triples are wrapped in a feedback loop before the main loop that is less good than 2 MOS FET's. Not bad for 1965/7. Micro detail is also where I notice SE amps giving more. SE class A to me the better class A. Krell is not my cup of tea.
Here below is what happens if a near perfect pentode triode null happens. Suddenly it looks like a nasty feedback amp at full power. I rejected this. 1.6 watt < - 60dB zero loop feed back. Don't much like KT88 , love EL34. KT88 was pushed out into this world the same time as me to the month.
Quad 33 is OK if carefully matched to source output level. I suspect 99% weren't. 200 kHz - 3dB 0.03% distortion 0VU !!! Use tape input set to high to avoid very nasty sound. It is actually less complex than one NE 5534 op amp. The tone controls actually work and do not change the sound even in micro detail. I would liken it to a car that can not climb hills in top gear. As awful rubbish goes it is almost innocent (Flat Earth Society awful as in Linn Naim . Tone controls = forget it). It is awful rubbish as with higher voltage rails it wouldn't be so fussy. The valve preamp also is a pile of junk. The Leak is superb by using it's valves better. Never connect a Varislope with modern cable unless sure it is very low capacitance. TV 75 ohm or nothing and keep it very short as it is anode output.
Here below is what happens if a near perfect pentode triode null happens. Suddenly it looks like a nasty feedback amp at full power. I rejected this. 1.6 watt < - 60dB zero loop feed back. Don't much like KT88 , love EL34. KT88 was pushed out into this world the same time as me to the month.
Quad 33 is OK if carefully matched to source output level. I suspect 99% weren't. 200 kHz - 3dB 0.03% distortion 0VU !!! Use tape input set to high to avoid very nasty sound. It is actually less complex than one NE 5534 op amp. The tone controls actually work and do not change the sound even in micro detail. I would liken it to a car that can not climb hills in top gear. As awful rubbish goes it is almost innocent (Flat Earth Society awful as in Linn Naim . Tone controls = forget it). It is awful rubbish as with higher voltage rails it wouldn't be so fussy. The valve preamp also is a pile of junk. The Leak is superb by using it's valves better. Never connect a Varislope with modern cable unless sure it is very low capacitance. TV 75 ohm or nothing and keep it very short as it is anode output.
OMG. I should say g2. To be honest I never tried it. I tried to get some TR34 made. I don't assume taking the g2+g3 out to be correct. The idea would be to make a PX25 type valve with indirect heater. Mr Kron would have been the man for that.
I met Mr Kron when his wife mistook me for someone who owed her $20 000 . I thought her such a wonderful person that I let her quiz me for two hours. The dispute is with a mutual friend. She gave in and said come meet Ricardo. His first words to me were " What is all this valve nonsense. Surely transistors are better" ? To which I said " Quite right " . He then looked very content and said " that's what I thought". He slipped then seamlessly into explaining the mistakes people make and how all 300B are fake . He realized I was an engineer and could speak simply about things . Eunice and I are friends now. Both the friend and she insist the other owes the other $20 000 to this very day. They are both right it seems. I badly miss Ricardo. I know JJ so could ask her. The Russians would be favorite. I only tell this as the words of Ricardo will be lost if not told. In 10 minutes he succeeded in telling me a lot.
BTW. None are triode. They are triode like. The small pentode quality is nice. 82% UL ( near triode end) is great if no loop feedback. My $20 000 owing friend likes PX25 as it has a sound like that yet is true troide. EL34 has very nice distortion. The more you ruin it the more it keeps trying to be itself. As someone said . KT88 is industrial and EL 34 musical. A good triode has a good pentode inside it if the design is universally right. Both in their own ways are fantastic engineering devices. Kitic saw how to be the forgotten triode. That is Anode to g1 feedback. The theoretical pentode has zero input current to produce an output current. None has ever existed. They get close. No other device does although FET is good. That would be if made with feedback the ideal device and would not produce any degradation due to copying loses.
http://diyaudioprojects.com/mirror/members.aol.com/sbench102/pentmode.html
I met Mr Kron when his wife mistook me for someone who owed her $20 000 . I thought her such a wonderful person that I let her quiz me for two hours. The dispute is with a mutual friend. She gave in and said come meet Ricardo. His first words to me were " What is all this valve nonsense. Surely transistors are better" ? To which I said " Quite right " . He then looked very content and said " that's what I thought". He slipped then seamlessly into explaining the mistakes people make and how all 300B are fake . He realized I was an engineer and could speak simply about things . Eunice and I are friends now. Both the friend and she insist the other owes the other $20 000 to this very day. They are both right it seems. I badly miss Ricardo. I know JJ so could ask her. The Russians would be favorite. I only tell this as the words of Ricardo will be lost if not told. In 10 minutes he succeeded in telling me a lot.
BTW. None are triode. They are triode like. The small pentode quality is nice. 82% UL ( near triode end) is great if no loop feedback. My $20 000 owing friend likes PX25 as it has a sound like that yet is true troide. EL34 has very nice distortion. The more you ruin it the more it keeps trying to be itself. As someone said . KT88 is industrial and EL 34 musical. A good triode has a good pentode inside it if the design is universally right. Both in their own ways are fantastic engineering devices. Kitic saw how to be the forgotten triode. That is Anode to g1 feedback. The theoretical pentode has zero input current to produce an output current. None has ever existed. They get close. No other device does although FET is good. That would be if made with feedback the ideal device and would not produce any degradation due to copying loses.
http://diyaudioprojects.com/mirror/members.aol.com/sbench102/pentmode.html
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This amp seemed to get a lot of praise. The copywrite seems a bit rich seeing as it is very obvious.
Single-Ended (SE) KT88 Tube Amplifier Schematic (with 6N1P driver)
This make very good reading. 813 is a favourite of mine. If correct it can be 0V biased as a transmitter valve. RH series.
http://rh-amps.blogspot.co.uk/
http://www.r-type.org/exhib/aai0203.htm
If you don't mind and have time my late brother. If he didn't know it wasn't worth knowing when valves. I did valves at college and more so than transistors. It was with the inherited stock I honour my brother. There were some unfinished chassis that were begging to be finished. Up to then I was interested just so as to share his world. When sitting with Mr Kondo the valves were of no interest and his amps a charming quirk.
http://www.r-type.org/search.php?zoom_sort=0&zoom_query=simon+pearson&zoom_per_page=10&zoom_and=1
Single-Ended (SE) KT88 Tube Amplifier Schematic (with 6N1P driver)
This make very good reading. 813 is a favourite of mine. If correct it can be 0V biased as a transmitter valve. RH series.
http://rh-amps.blogspot.co.uk/
http://www.r-type.org/exhib/aai0203.htm
If you don't mind and have time my late brother. If he didn't know it wasn't worth knowing when valves. I did valves at college and more so than transistors. It was with the inherited stock I honour my brother. There were some unfinished chassis that were begging to be finished. Up to then I was interested just so as to share his world. When sitting with Mr Kondo the valves were of no interest and his amps a charming quirk.
http://www.r-type.org/search.php?zoom_sort=0&zoom_query=simon+pearson&zoom_per_page=10&zoom_and=1
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Just for interest,
I changed the 1K resistor across the speaker output connectors to a thick film 5W and I am convinced it sounds better..Yes I know..It doesn't need to be high wattage..and the type??
I have had the same thing in the past...it looks like this..I just soldered some solid core onto them and connected.
https://www.google.co.uk/search?q=thick+film+resistor&source=lnms&tbm=isch&sa=X&ei=es6xU_ToCMPIPNKDgKAG&ved=0CAcQ_AUoAg&biw=1524&bih=696#facrc=_&imgdii=_&imgrc=qRM6IkGX5DA3lM%253A%3Bag2p58qXbelllM%3Bhttp%253A%252F%252Fwww.electronicproducts.com%252Fimages2%252FFAJH_Ohmite_3_Oct2012.gif%3Bhttp%253A%252F%252Fwww.electronicproducts.com%252FPassive_Components%252FResistors_and_Potentiometers%252FAlumina_substrate_packs_in_passive_components.aspx%3B250%3B250
Regards
M. Gregg
I changed the 1K resistor across the speaker output connectors to a thick film 5W and I am convinced it sounds better..Yes I know..It doesn't need to be high wattage..and the type??
I have had the same thing in the past...it looks like this..I just soldered some solid core onto them and connected.
https://www.google.co.uk/search?q=thick+film+resistor&source=lnms&tbm=isch&sa=X&ei=es6xU_ToCMPIPNKDgKAG&ved=0CAcQ_AUoAg&biw=1524&bih=696#facrc=_&imgdii=_&imgrc=qRM6IkGX5DA3lM%253A%3Bag2p58qXbelllM%3Bhttp%253A%252F%252Fwww.electronicproducts.com%252Fimages2%252FFAJH_Ohmite_3_Oct2012.gif%3Bhttp%253A%252F%252Fwww.electronicproducts.com%252FPassive_Components%252FResistors_and_Potentiometers%252FAlumina_substrate_packs_in_passive_components.aspx%3B250%3B250
Regards
M. Gregg
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