Here a picture of the 300B diferential Monoblocks and the big preamp.
I do not talk much about the sound now because when Allen gets back we will listen again and discuss a bit. Let me say so much that the 2 x 18W is more then enough for my 100dB efficient system. Hiss and Hum from the big preamp is not audible at decent volume. The sound is surprisingly close to what i do but not similar of cause.
When you look for a clasical syruppy or as Allen whould say "fruity" sound you are wrong here. The sound is fast and transparent but lacks spitt although Allen implements the Neumann pole and loads the cartridge very lightly with 47kOhm.
I do not talk much about the sound now because when Allen gets back we will listen again and discuss a bit. Let me say so much that the 2 x 18W is more then enough for my 100dB efficient system. Hiss and Hum from the big preamp is not audible at decent volume. The sound is surprisingly close to what i do but not similar of cause.
When you look for a clasical syruppy or as Allen whould say "fruity" sound you are wrong here. The sound is fast and transparent but lacks spitt although Allen implements the Neumann pole and loads the cartridge very lightly with 47kOhm.
Now for something that has nothing to do with High End. I have some poor musician friends that can not even afford a 200,-€ phonostage but nevertheless whould like to listen to Vinyl or digitise to the computer.
I whould like to do something about it and bought a Dynavox TC - 750 MM stage.
I measured it and found that the +- 0.5dB spec from 20Hz to 20kHz is rather optimistic as expected.
The circuit has -3dB at 20Hz and +1.5dB at 20kHz. The squarewave looks terible so i spare you that and it does not like to be driven hard or it gets unstable.
I bought it for around 20,-€ including tax and shipping so what does that buy you ?
First i was surprised that the designer went to the trouble to do a discrete circuit.
The input stage is a rather odd interpretation of the Dinsdale from 1965 and he added a simple open loop emitter follower. Look at the funny biasing cascade and the unusual feedback structure aroud the input pair. On the other hand i spotted 6 very nice 2SC1815 BJTs, some decent quality Rubicon elcaps, 1% metall film resistors and gold plated input and output jacks, all in a nice aluminum cabinet.
Again D.Self comes to the rescue and i will rebuild the circuit to a Walker stage with Self bootstrapping. Now we are firmly in the mid 70th and i like the circuit quite well.
The input has higher impedance so i can use a foil cap here. The emmitter folower and the output cap are in a feedback loop and drive the RIAA circuit with low impedance.
I could even try to use it as an MC stage because the 2SC1815 has only 50 Ohms Rbb.
R17 and R2 have to be lowered for that and distortion could be reduced by substituting R14 with a constant current source. Ideally the circuit should be run on higher voltage, say 24V.
I whould like to do something about it and bought a Dynavox TC - 750 MM stage.
I measured it and found that the +- 0.5dB spec from 20Hz to 20kHz is rather optimistic as expected.
The circuit has -3dB at 20Hz and +1.5dB at 20kHz. The squarewave looks terible so i spare you that and it does not like to be driven hard or it gets unstable.
I bought it for around 20,-€ including tax and shipping so what does that buy you ?
First i was surprised that the designer went to the trouble to do a discrete circuit.
The input stage is a rather odd interpretation of the Dinsdale from 1965 and he added a simple open loop emitter follower. Look at the funny biasing cascade and the unusual feedback structure aroud the input pair. On the other hand i spotted 6 very nice 2SC1815 BJTs, some decent quality Rubicon elcaps, 1% metall film resistors and gold plated input and output jacks, all in a nice aluminum cabinet.
Again D.Self comes to the rescue and i will rebuild the circuit to a Walker stage with Self bootstrapping. Now we are firmly in the mid 70th and i like the circuit quite well.
The input has higher impedance so i can use a foil cap here. The emmitter folower and the output cap are in a feedback loop and drive the RIAA circuit with low impedance.
I could even try to use it as an MC stage because the 2SC1815 has only 50 Ohms Rbb.
R17 and R2 have to be lowered for that and distortion could be reduced by substituting R14 with a constant current source. Ideally the circuit should be run on higher voltage, say 24V.
I rebuild the Dynavox but no success so far. The circuit is unstable. Because i had again visitors today i did not find time to fix it.
What i had time for was thinking about how i can use the discrete OPamp i am designing with a team of well known contributors. First i came up with a name to identify it. I decided on JOSI. That is the first letters of my name and the first letters of one of the co designers and a song by Steely Dan i like.
So why the hell are we designing a discrete Opamp ?
Having tried nearly everything i could do with integrated Opamps of latest vintage i am comming into a one way road with maybe a dead end. Mind you, the best of my designs perform well over my initial expectation, and that is not only my personal experience. Today my guests and i compared the latest version of the JG-Self ( and that is not even my best desing i think) to some very expensive and innovative preamps of tube and transistor origin and i did not hear anything new that i had not heard before. Each piece of gear has it´s own personality but i think i have the advantage that i can optimise my designs to my taste and my system so under different circumstances the outcome of a listening session with the same electronics could be different. Nevertheless, i get more and more confidence in what i am doing.
So again : Why a discrete Opamp ? First we have more options. An integrated Opamp is mostly designed for high open loop gain and low open loop bandwidth. In theory negative feedback can set the gain, reduce distortion and widen the frequency response
so fix the problem. Our discrete design has a different philosphie. We try to make the open loop frequency response wide and the open loop distortion low. Of cause we try also to have a lot of gain but not at the cost of the other parameters. So instead of 140dB of gain we have maybe 70dB but with much higher bandwidth and much lower distortion. If that sound better we have to see. Sofar it is a game on the computer but the circuit is advanced and mature enough to be put on a PCB. Of cause we try to use the best passive and active components we can and also put in some convenience. For example a noninverting and an inverting servo is on board and there is manual DC trimming too. It has a wide supply range and lots of current drive ability so even a headphone amp or a small poweramp ( at least a driver) could be build. Open loop input impedance is high and output impedance is low. We use no caps ( elcaps or other wise) ( with the exception of PSU decoupling and Miller compensation) in the current sources or voltage references. Active components where choosen with great care after a lot of discussion about performance, availlability and alternatives.
And the most important argument, but that can only be proven subjectively: we hope it will sound better then an integrated alternative, that is also the reason we care about bandwidth, noise and distortion. This is not a sound processor but a clean and fast device. So what can be done with that JOSI. Well, nearly everything that can be done with a conventional opamp. Series feedback, shunt feedback, filters, buffers, INAs etc.
Noise is around 2nV/QHz so i whould not put it at the input of a very low output moving coil but everything over 1mV should be fine. But lets stop the talking or i get too enthusiastic. The first circuit i designed is, guess what ? A phonostage !
This one has an open loop input stage with transimedance 75uSec RIAA and the rest done capacitive active, It´s balanced-in balanced-out. I get a little tyred, so if you have questions, ask me. Servos and some other on board features have been omitted for clarity. This sentence is for you Scott, i hope you like it.
What i had time for was thinking about how i can use the discrete OPamp i am designing with a team of well known contributors. First i came up with a name to identify it. I decided on JOSI. That is the first letters of my name and the first letters of one of the co designers and a song by Steely Dan i like.
So why the hell are we designing a discrete Opamp ?
Having tried nearly everything i could do with integrated Opamps of latest vintage i am comming into a one way road with maybe a dead end. Mind you, the best of my designs perform well over my initial expectation, and that is not only my personal experience. Today my guests and i compared the latest version of the JG-Self ( and that is not even my best desing i think) to some very expensive and innovative preamps of tube and transistor origin and i did not hear anything new that i had not heard before. Each piece of gear has it´s own personality but i think i have the advantage that i can optimise my designs to my taste and my system so under different circumstances the outcome of a listening session with the same electronics could be different. Nevertheless, i get more and more confidence in what i am doing.
So again : Why a discrete Opamp ? First we have more options. An integrated Opamp is mostly designed for high open loop gain and low open loop bandwidth. In theory negative feedback can set the gain, reduce distortion and widen the frequency response
so fix the problem. Our discrete design has a different philosphie. We try to make the open loop frequency response wide and the open loop distortion low. Of cause we try also to have a lot of gain but not at the cost of the other parameters. So instead of 140dB of gain we have maybe 70dB but with much higher bandwidth and much lower distortion. If that sound better we have to see. Sofar it is a game on the computer but the circuit is advanced and mature enough to be put on a PCB. Of cause we try to use the best passive and active components we can and also put in some convenience. For example a noninverting and an inverting servo is on board and there is manual DC trimming too. It has a wide supply range and lots of current drive ability so even a headphone amp or a small poweramp ( at least a driver) could be build. Open loop input impedance is high and output impedance is low. We use no caps ( elcaps or other wise) ( with the exception of PSU decoupling and Miller compensation) in the current sources or voltage references. Active components where choosen with great care after a lot of discussion about performance, availlability and alternatives.
And the most important argument, but that can only be proven subjectively: we hope it will sound better then an integrated alternative, that is also the reason we care about bandwidth, noise and distortion. This is not a sound processor but a clean and fast device. So what can be done with that JOSI. Well, nearly everything that can be done with a conventional opamp. Series feedback, shunt feedback, filters, buffers, INAs etc.
Noise is around 2nV/QHz so i whould not put it at the input of a very low output moving coil but everything over 1mV should be fine. But lets stop the talking or i get too enthusiastic. The first circuit i designed is, guess what ? A phonostage !
This one has an open loop input stage with transimedance 75uSec RIAA and the rest done capacitive active, It´s balanced-in balanced-out. I get a little tyred, so if you have questions, ask me. Servos and some other on board features have been omitted for clarity. This sentence is for you Scott, i hope you like it.
Tube it is !
Hi Joachim,
I feel, it is my fault that now you´re dancing on the music reproduced by these amp´s !
I hope to have the chance to listen to them in the near future.
Can you tell me what grabbed you when you where listening to the music?
Was it magic caused by tube's or.............??????
I'm all ears, this is great
Cheers,
José
BTW: what are we doing at 4:20 in the morning in Europe? Posting on DIYAudio.com
Audiofanatic
Hi Joachim,
I feel, it is my fault that now you´re dancing on the music reproduced by these amp´s !
I hope to have the chance to listen to them in the near future.
Can you tell me what grabbed you when you where listening to the music?
Was it magic caused by tube's or.............??????
I'm all ears, this is great
Cheers,
José
BTW: what are we doing at 4:20 in the morning in Europe? Posting on DIYAudio.com
Audiofanatic
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Audiofanatic, i say it again. I am sleeping 2 to 3 hours in the afternoon so do not worry, i get enough sleep. I stay awake at night because i do a lot of busyness with the United States and Japan. So it is in the afternoon in the US and in the mornig in Japan when i am working at night here. I have the luck that i have a very tolerant artist family.
Allens amp is a masterpiece in many ways. It does not sound like a tube and it does not sound like a transistor eather. It sounds like music. Energetic, sweet, brutal, esoteric. You name it. Lot´s of expensive Lundahl iron in there and made like a 70th measurement instrument. Allen build amps since 50 years and you hear it. Honestly speaking this amp impressed me even more then his preamps, as good as they are.
His amp is that kind of product that changes your life. It is capable of a paradigm shift.
Considering that Allen does not care about the distortion profile and the amp is running open loop it is even more of a miracle. It is fast nevertheless ( -3dB @ 250kHz), so the quality is inherent and not forced. Allen is very stubborn about his priciples and after a lot of hard and intense discussion with him about the whys and whats i just surrendered to the result. It´s that good, progress is still posible and amps do not sound alike if they have less then 0.1% distortion, a response from 20 to 20kHz, do not clip and have low noise. I know, this is not very popular in technically oriented cicles and i have a BIG problem with the zerro feedback topology. If Allen whould give the amp to me for reconstruction whould certainly try to use feedback but i have to except him as the artist he is. Period.
Allens amp is a masterpiece in many ways. It does not sound like a tube and it does not sound like a transistor eather. It sounds like music. Energetic, sweet, brutal, esoteric. You name it. Lot´s of expensive Lundahl iron in there and made like a 70th measurement instrument. Allen build amps since 50 years and you hear it. Honestly speaking this amp impressed me even more then his preamps, as good as they are.
His amp is that kind of product that changes your life. It is capable of a paradigm shift.
Considering that Allen does not care about the distortion profile and the amp is running open loop it is even more of a miracle. It is fast nevertheless ( -3dB @ 250kHz), so the quality is inherent and not forced. Allen is very stubborn about his priciples and after a lot of hard and intense discussion with him about the whys and whats i just surrendered to the result. It´s that good, progress is still posible and amps do not sound alike if they have less then 0.1% distortion, a response from 20 to 20kHz, do not clip and have low noise. I know, this is not very popular in technically oriented cicles and i have a BIG problem with the zerro feedback topology. If Allen whould give the amp to me for reconstruction whould certainly try to use feedback but i have to except him as the artist he is. Period.
Allen Wright's amp
Joachim Gerhard;2171865]Audiofanatic, i say it again. I am sleeping 2 to 3 hours in the afternoon so do not worry, i get enough sleep. I stay awake at night because i do a lot of busyness with the United States and Japan. So it is in the afternoon in the US and in the mornig in Japan when i am working at night here. I have the luck that i have a very tolerant artist family.
We are alike in this LOL I do the same Except sleep in the afternoon.
Allens amp is a masterpiece in many ways. It does not sound like a tube and it does not sound like a transistor eather. It sounds like music. Energetic, sweet, brutal, esoteric. You name it. Lot´s of expensive Lundahl iron in there and made like a 70th measurement instrument.
Mr. Wright knows what matters most in tube audio "PSU" that's the way to put things sing in such an amplifier!
Allen build amps since 50 years and you hear it. Honestly speaking this amp impressed me even more then his preamps, as good as they are.
His amp is that kind of product that changes your life. It is capable of a paradigm shift.
Considering that Allen does not care about the distortion profile and the amp is running open loop it is even more of a miracle. It is fast nevertheless ( -3dB @ 250kHz), so the quality is inherent and not forced. Allen is very stubborn about his priciples and after a lot of hard and intense discussion with him about the whys and whats i just surrendered to the result. It´s that good, progress is still posible and amps do not sound alike if they have less then 0.1% distortion, a response from 20 to 20kHz, do not clip and have low noise. I know, this is not very popular in technically oriented cicles and i have a BIG problem with the zerro feedback topology.
Joachim, it seems that we disagree on this topic, I second this topology and so agree with Mr. Wright; I prefer zero feedback topology (ask Jaap from Hanze why) he thought me to work this way and he's a master in tube amplifiers
If Allen whould give the amp to me for reconstruction whould certainly try to use feedback but i have to except him as the artist he is. Period.
I'm honestly moved by your acceptance of Mr. Wright's way of work, that indicates that you are open for new things in life and that's teh only way to learn more and more. Keep up the open spirit !
My professor always told me: "The one that didn't change his/her mind on the long run, didn't learn anything in life".
I hope that you'll have the chance to rebuild this amp of him and perhaps you'll go back to his topology, and than again maybe not
I always say, "there is more (in life) between heaven and earth"
All the best and thanks for your posts here on DIYAudio.
Cheers,
José
Sorry for this multi-quote thing I don't know how it works.
Audiofanatic
Joachim Gerhard;2171865]Audiofanatic, i say it again. I am sleeping 2 to 3 hours in the afternoon so do not worry, i get enough sleep. I stay awake at night because i do a lot of busyness with the United States and Japan. So it is in the afternoon in the US and in the mornig in Japan when i am working at night here. I have the luck that i have a very tolerant artist family.
We are alike in this LOL I do the same
Except sleep in the afternoon.Allens amp is a masterpiece in many ways. It does not sound like a tube and it does not sound like a transistor eather. It sounds like music. Energetic, sweet, brutal, esoteric. You name it. Lot´s of expensive Lundahl iron in there and made like a 70th measurement instrument.
Mr. Wright knows what matters most in tube audio "PSU" that's the way to put things sing in such an amplifier!
Allen build amps since 50 years and you hear it. Honestly speaking this amp impressed me even more then his preamps, as good as they are.
His amp is that kind of product that changes your life. It is capable of a paradigm shift.
Considering that Allen does not care about the distortion profile and the amp is running open loop it is even more of a miracle. It is fast nevertheless ( -3dB @ 250kHz), so the quality is inherent and not forced. Allen is very stubborn about his priciples and after a lot of hard and intense discussion with him about the whys and whats i just surrendered to the result. It´s that good, progress is still posible and amps do not sound alike if they have less then 0.1% distortion, a response from 20 to 20kHz, do not clip and have low noise. I know, this is not very popular in technically oriented cicles and i have a BIG problem with the zerro feedback topology.
Joachim, it seems that we disagree on this topic, I second this topology and so agree with Mr. Wright; I prefer zero feedback topology (ask Jaap from Hanze why) he thought me to work this way and he's a master in tube amplifiers
If Allen whould give the amp to me for reconstruction whould certainly try to use feedback but i have to except him as the artist he is. Period.
I'm honestly moved by your acceptance of Mr. Wright's way of work, that indicates that you are open for new things in life and that's teh only way to learn more and more. Keep up the open spirit !
My professor always told me: "The one that didn't change his/her mind on the long run, didn't learn anything in life".
I hope that you'll have the chance to rebuild this amp of him and perhaps you'll go back to his topology, and than again maybe not
I always say, "there is more (in life) between heaven and earth"
All the best and thanks for your posts here on DIYAudio.
Cheers,
José
Sorry for this multi-quote thing I don't know how it works.
Audiofanatic
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Hi All !
Unfortunately the amp has left my home but i can ask Allen if he provides some photos and more information. As far as i know he uses a differential topology and Kathode and Anode coupling 50/50.
The amp looks like his 300B monoblocks you can see on his web page but bigger.
Still the amp is easy to carry by one person. This Lundahl transfomers and coils are surprisingly small.
Allen does not use NFB because he claims that with feedback the amp looses sparkle and transparency. I have made the oposite experience. Most amps i tryed with zerro or low feedback had trouble with complex material. This is not the case with Allen design.
For example on the first track of "The Dude" by Quincy Jones, "Ai No Corrida" there is a banjo playing all the time in the backround. I knew it was there but i never heard it so clear.
By the way, i have no plan to rebuild it but i asked Allen if he could lower the already low hum. I have a 100dB 8Ohm effient speaker system and even 1mV of humm is audible.
Allen promissed that he can solve that last small problem easyly but did not find time so far to optimise that. On speakers with effiency of 91dB like the Sonics Allegria 1.5 i have in the factory it is dead quiet.
P.S.: Yes, Allen cares a lot about powersupply and promissed that he can teach me one thing or the other.
P.P.S.: Yes, Jaap is a Tube Guru and a very pleasant person too.
He must have repaired more High End equipment then anybody else i know, so he knows his passion inside out.
Unfortunately the amp has left my home but i can ask Allen if he provides some photos and more information. As far as i know he uses a differential topology and Kathode and Anode coupling 50/50.
The amp looks like his 300B monoblocks you can see on his web page but bigger.
Still the amp is easy to carry by one person. This Lundahl transfomers and coils are surprisingly small.
Allen does not use NFB because he claims that with feedback the amp looses sparkle and transparency. I have made the oposite experience. Most amps i tryed with zerro or low feedback had trouble with complex material. This is not the case with Allen design.
For example on the first track of "The Dude" by Quincy Jones, "Ai No Corrida" there is a banjo playing all the time in the backround. I knew it was there but i never heard it so clear.
By the way, i have no plan to rebuild it but i asked Allen if he could lower the already low hum. I have a 100dB 8Ohm effient speaker system and even 1mV of humm is audible.
Allen promissed that he can solve that last small problem easyly but did not find time so far to optimise that. On speakers with effiency of 91dB like the Sonics Allegria 1.5 i have in the factory it is dead quiet.
P.S.: Yes, Allen cares a lot about powersupply and promissed that he can teach me one thing or the other.
P.P.S.: Yes, Jaap is a Tube Guru and a very pleasant person too.
He must have repaired more High End equipment then anybody else i know, so he knows his passion inside out.
Can I suggest you add an isolation resistor at the output of this circuit - maybe just 1k will stabilise it.
Alternately, add a base stopper to the emitter follower, because almost certainly it's the emitter follower thats oscillating.
I used that same three transistor circuit with EF output with the RIA taken from the EF's output years ago, and had the same troubles. Either or both R's should fix it.
Regards, Allen
Simon, your resistors you send to me sound well. I can only say again : anybody that is interested to hear how different resistors sound is invited to my home. That is the only "prove" i can provide. Sofar, listeners with enough experience could hear a difference easily. I know, not many people have a system like me so under certain cicumstances the difference may be swaped by a resolution problem. When you can not hear it, you to not beleave it, that is trivial.
Allen : i hope you come back soon. I miss your amps badly. Maybe the next time you come i can invite some more people and you can hold one of your interesting seminars.
Allen : i hope you come back soon. I miss your amps badly. Maybe the next time you come i can invite some more people and you can hold one of your interesting seminars.
Thanks Allen for sugestions how i can fix the 3 transistor RIAA stage, You must know this is not an important project at all. I just have a weak spot for people that can not afford our professional products we make. The cost of high end products whent over the top and that is one of the reasons i try to help people to do somthing themselfs by building one of the circuits i post here. Anyway, thanks that you care about this little detail. I apreciate your honesty. We have to bring new people into he high end or our passion will not more exist when we are not more around.
Allen : i hope you come back soon. I miss your amps badly. [/QUOTE said:Hi Joachim,
I know a good way to solve this problem; buy the amplifiers from Allen, that way you'll have the chance to listen to it whenever you want. (Joke)
To Allen; give the guy a tremendous discount, he'll take it
Cheers,
Audiofanatic
Do you search for a job ? You are a great salesman.
Unfortunately i have a 17 years old boy that in doing his drivers licence, learns to play the horn with a canadian professor, dances in a professional club, wants the best computer, a cell phone etc.
My wife is quite demading too and i just bought an Audionet MAX2 transistor amp pair.
.....i just can not afford that amp at the moment but i can not afford to not have it too.
Help !!!!
Unfortunately i have a 17 years old boy that in doing his drivers licence, learns to play the horn with a canadian professor, dances in a professional club, wants the best computer, a cell phone etc.
My wife is quite demading too and i just bought an Audionet MAX2 transistor amp pair.
.....i just can not afford that amp at the moment but i can not afford to not have it too.
Help !!!!