John, I know you to be a 10:1 margin kind of guy. This would
mean that you were only expecting to drive 15 mph.
😎
O.T.
Actually I have to use tubes for that application! They really do make a difference. Tube mic preamp into a limiter than to an A/D sounds better than straight into the mixing consoles I have tried. Of course I have an untrained announcer who tends to get carried away and vary widely in level from inattentive comments near the microphone to screaming straight in while excited.
On T.
Once you rule out record warp for mechanical reasons then the dynamic range from a record is greatly reduced. At 10nv/hz 20khz bandwidth or 1.4uv total noise your opamp only has 138 or so db of dynamic range, you might get away with that!
Everyone, when I comes to layout, I am useless. I leave that to my able colleague, Carl Thompson, the 'T' in CTC and have done so for more than 25 years. His layouts are 'works of art' and I will work with nothing less. Carl is not interested in this design at the moment, although he knows about it.
Carl designed the Vendetta, Lineage (with Saul Marantz), CTC Blowtorch, JC-1, JC-2, the new JC-3 phono preamp, just released, and the $40,000 Constellation Orion phono stage (on my bench at the moment).
To leave an amateur to do this, is OK, but on your own time. I am not equipped to add significant comments one way or another. Perhaps another thread could be started with this project in mind. However, I recommend that you hold back, until we develop the AUDI, rather than the Beatle, and spend your time laying that out.
Carl designed the Vendetta, Lineage (with Saul Marantz), CTC Blowtorch, JC-1, JC-2, the new JC-3 phono preamp, just released, and the $40,000 Constellation Orion phono stage (on my bench at the moment).
To leave an amateur to do this, is OK, but on your own time. I am not equipped to add significant comments one way or another. Perhaps another thread could be started with this project in mind. However, I recommend that you hold back, until we develop the AUDI, rather than the Beatle, and spend your time laying that out.
Engineering as opposed to tinkering is about making choices. There are points of diminishing returns where small improvements in performance add steeply to cost and then there is a point beyond which improved performance is only theoretical and demonstrable in a laboratory but of no practical benefit to anyone. There is also the risk that improved performance in areas of no value can have negative consequences in other areas that do. Lack of knowledge of these principles is the hook that keeps audiophiles coming back for more and more expensive equipment, sometimes shopping for their next replacement product before they've opened the box containing their most recent worldbeater.
As the vinyl phonograph record is a dead technology going nowhere ever again in all likelihood, the maximum requirements to play any phonograph record that exists should be well known. Frequency range, dynamic range from noise floor to greatest modulation. Questions of FR are easly solved in most cases by use of EQ, an indespensible tool to sound engineers even if it is an athema to audiophiles (how can you sell new expensive products when old cheap ones can be made to sound the same using a simple device? Easy, convince those with the money to buy expensive new products not to use cheaply availble tools by convincing them it will do more harm than good.)
If there is an engineering challenge left here, it should be to design the best possible circuit that can be built at any price and then design a cheap one that performs identically by subjectively comparing them. That is a challenge worthy of an engineer. It should also be designed to be used with any associated equipment without compromising its performance with respect to its competition. The rest is hooey.
There are some current feedback Opamps with less then 2nV/qHz but again this may not be good enough. They can be paralleled of cause AD INFINITUM.
One example : LME49713
One example : LME49713
Vinyl is small but not dead. Just yesterday i listened to an old mono Louis Armstrong after a really busy day and it had such a good effect on me like i had taken a magic pill. I felt much better after that treatment. The record was in mono and dynamics and frequency response restricted ( although it was in mint condition so scratches and hiss was surprisingly low ), but it brought that "old feeling" back.
If a MC section is made as a step-up in front of an opamp based MM phono stage, a discrete design may be better -- both in terms of audio quality and $$$.
It should be "very easy" to design a good amp with say 20 dB gain for very low level inputs. Here we have the same advantage as tube amp designers, the large ratio between audio levels and supply voltages.
It should be "very easy" to design a good amp with say 20 dB gain for very low level inputs. Here we have the same advantage as tube amp designers, the large ratio between audio levels and supply voltages.
Keep on target. You amateurs cannot afford REAL discrete devices at this point. Let others make second tier designs somewhere else on this website. Let us approach our objective, and we all might learn something. Why? Because we will be matching apples to apples, not apples to oranges, or its equivalent.
For the record, I already KNOW how to make extremely high performance discrete designs, and have been doing so for more than 40 years. It is the rest of you, who wander in the dark, so to speak, and are equally quick to jump to a partially discrete design without learning about topology differences with IC designs.
For the record, I already KNOW how to make extremely high performance discrete designs, and have been doing so for more than 40 years. It is the rest of you, who wander in the dark, so to speak, and are equally quick to jump to a partially discrete design without learning about topology differences with IC designs.
Last edited:
Joachim, a friend of mine just dumped a bunch of 78's. What a loss. You know, from hi end experience, why we waste our time with phono. It is just like why people waste time and money eating at a great restaurant, or enjoy a wine better than 2 buck Chuck. It gives a sense that there is more than just McDonalds out there, although that might well do much of the time.
Ooops, sorry John. I have some LT1028s ant LT1115s in my drawer. Should I blow the dust of them now? I know that the almighty Doug Self don't like them. But they have really low noise. And to me - just sitting in my drawer for years and years - are really cheap😀
The strange problem in not-so-hi-gain amps combined with really low noise is the current demand to drive the low impedance feedback. If asked 25+ years ago, I would have added a LT1010ct inside the FB loop to drive the feedback.
The strange problem in not-so-hi-gain amps combined with really low noise is the current demand to drive the low impedance feedback. If asked 25+ years ago, I would have added a LT1010ct inside the FB loop to drive the feedback.
So what is the goal ? Less then 1nV/qHz with only one Opamp is hard. Paralleling 4 whould bring the noise down by 6dB and the quadruple could drive nearly 100mA.
John
Twice now I know where Thunderbird fortified wine was presented to wine tastings, both times there were tasters who pick it as a good wine!
As to old 78's there were many performances recorded that are not available elsewhere, the emotion of the music is there no mater how poor the reproduction.
Does anyone have any idea how many new recordings come out each year? How many of those will you want to listen to years later?
I know John you still groove to the "Purple People Eater!"
ES
Here in Germany we have no shortage of new Vinyl comming out. Many of those are from a digital master of cause but our artists here find it kind of prestigious to bring out a piece of PVC in a paper jacket. Some times a CD is packed in for free.
2 quad, this is NOT about you! It is about engineering design. OF COURSE, you should put anything that you have in you junk box in your own circuit, IF you chose to make one, but it is not good engineering to chose these devices, TODAY, for modern audio reproduction when cheaper and faster IC op amps are available from the same manufacturers or someone down the road. I would save these devices for test equipment, that is where I use them, today, and have for the last 15 years.
So do we have a ranking of low en/in devices suitable for audio? Low Ib is also important. Other parameters?
Balanced is king
Leaving the ultra-minimalistic for a short while, why don't real phono amps have balanced inputs? The cartridge itself is inherently balanced, ground is just a shield from the amp to reduce hum.
Several manufacturers offer good instrumentation amps intended for microphone preamps. TI, AD, Thats etc. These may be used as a really good phono front end.
To bad that the consumer audio industry never understood the real meaning of "balanced" 😀
Leaving the ultra-minimalistic for a short while, why don't real phono amps have balanced inputs? The cartridge itself is inherently balanced, ground is just a shield from the amp to reduce hum.
Several manufacturers offer good instrumentation amps intended for microphone preamps. TI, AD, Thats etc. These may be used as a really good phono front end.
To bad that the consumer audio industry never understood the real meaning of "balanced" 😀
Thats what i do with my 3 Opamp INAs. I tryed integated INAs and i could never get a certain sharpness in the sound away. Also the internal resistors are quite high so you have to make compromises between gain and noise. An INA made of 3 separate Opamp allows to avoid that compromise.
- Status
- Not open for further replies.