leadbreath
Well-known member
Holy **** Dave!
You are my hero!! :-*
How is life in France treating you?
You are my hero!! :-*
How is life in France treating you?
U73b from scratch
- Thread starter DaveP
- Start date
Help Support GroupDIY Audio Forum:
Life in France is wonderful thanks, but hard work too.
Because of a massive pension shortfall, we had to sell up in the UK and buy cheap here, so at 65 I am starting over again.
It has taken me 6 months to put in a wood fired central heating system from scratch and last week we had our first hot water and baths in our own house! ( I should add that we had been bathing at a friends until then). ???
I do the electronics in the evening to keep me sane, otherwise all work and no play makes Jack a dull boy
The UK has changed so much since we were young, so being strangers in France is somehow better than feeling a stranger in your own country; does that make sense?
The French here could not be nicer, our neighbours give us vegetables and we give everyone our eggs from our chickens. I try to speak French all the time, which is appreciated (Google translate is a great asset). I understand that learning a language is one of the best things you can do to keep your brain cells in good shape. French is probably the most beautiful language in the world, if a little cut down compared to English.
My best tip: when talking about your neighbour's cat, never sound the T at the end of Chat, otherwise you will be talking about her pussy instead.
best
DaveP
Because of a massive pension shortfall, we had to sell up in the UK and buy cheap here, so at 65 I am starting over again.
It has taken me 6 months to put in a wood fired central heating system from scratch and last week we had our first hot water and baths in our own house! ( I should add that we had been bathing at a friends until then). ???
I do the electronics in the evening to keep me sane, otherwise all work and no play makes Jack a dull boy
The UK has changed so much since we were young, so being strangers in France is somehow better than feeling a stranger in your own country; does that make sense?
The French here could not be nicer, our neighbours give us vegetables and we give everyone our eggs from our chickens. I try to speak French all the time, which is appreciated (Google translate is a great asset). I understand that learning a language is one of the best things you can do to keep your brain cells in good shape. French is probably the most beautiful language in the world, if a little cut down compared to English.
My best tip: when talking about your neighbour's cat, never sound the T at the end of Chat, otherwise you will be talking about her pussy instead.
best
DaveP
bernbrue
Well-known member
Hi Dave,
I have my wife's family in France (Bretagne) and never learnt French at school. In the beginning I tried to cut the long phrases into bits, just to get the topic what they were talking about. After many years of regular visits everything is fine now. I can take part in discussions and at least I can buy cigarettes, wine, baguettes and cheese on my own. Even a fishing trip with my father in law never gets boring. There is so much to talk about. Your U73b thread is fantastic. Watching every step of your progress.
Bernd
I have my wife's family in France (Bretagne) and never learnt French at school. In the beginning I tried to cut the long phrases into bits, just to get the topic what they were talking about. After many years of regular visits everything is fine now. I can take part in discussions and at least I can buy cigarettes, wine, baguettes and cheese on my own. Even a fishing trip with my father in law never gets boring. There is so much to talk about. Your U73b thread is fantastic. Watching every step of your progress.
Bernd
leadbreath
Well-known member
I was born in South Africa to Spanish parents so I was a foreigner in SA, I moved to Spain in 2000 and I was a foreigner there too as I lived abroad all my life. Now I live in England with all the other foreigners and I still don't feel "At home" so to speak.
I guess at the end of the day we are all residents of planet Earth and that's sometimes hard to remember...
The area of France where I live has many similarities to the England that has gone forever.
This is what has changed in my lifetime:-
Increase of population from 45M to 60M.
Front gardens cemented over for cars.
Litter everywhere.
Graffiti everywhere.
Vandalism.
Drug related crime.
Obesity.
Lack of social cohesion.
Girls getting drunk.
I could go on but its off topic,
These are issues that you are no doubt familiar with, but they just did not exist when I was growing up, I live in the least prosperous part of France but they don't exist here either, that's why I love it.
best
DaveP
This is what has changed in my lifetime:-
Increase of population from 45M to 60M.
Front gardens cemented over for cars.
Litter everywhere.
Graffiti everywhere.
Vandalism.
Drug related crime.
Obesity.
Lack of social cohesion.
Girls getting drunk.
I could go on but its off topic,
These are issues that you are no doubt familiar with, but they just did not exist when I was growing up, I live in the least prosperous part of France but they don't exist here either, that's why I love it.
best
DaveP
Back to work.
The front panel wiring is now complete, not something to do when you're tired!
The switch next to the meter is the release timing with all the caps attached. The switch top right is the in/out switch, this allows an instant comparison of the signal with and without compression. The switch bottom right is the Limiter/ Compressor switch.
Here's the view from the back.
And finished comp from the top
I now have to put in the tubes and check the DC heater voltage is 6.3V. If that is ok I have to fit the correct HT/B+ dropper resistor. Although the Power is 230V here, I have a step-down transformer to test on 115V for the US. All this will be in the next post.
best
DaveP
The front panel wiring is now complete, not something to do when you're tired!
The switch next to the meter is the release timing with all the caps attached. The switch top right is the in/out switch, this allows an instant comparison of the signal with and without compression. The switch bottom right is the Limiter/ Compressor switch.
Here's the view from the back.
And finished comp from the top
I now have to put in the tubes and check the DC heater voltage is 6.3V. If that is ok I have to fit the correct HT/B+ dropper resistor. Although the Power is 230V here, I have a step-down transformer to test on 115V for the US. All this will be in the next post.
best
DaveP
thomasdf
Well-known member
Dave, this is turning great! Glad to read you are finally able to have hot water!
Is the barn / studio getting ready too?
I haven't made much progress on the Federal, but I keep thinking about it every day haha
Maybe it could be fun to pay you a quick visit at some point I get to be in the area. You know you are welcome whenever you want in Paris!
Cheers
ps: back to topic... your u73 is CRAZY. Keep them close up electronic porn pictures coming!
Is the barn / studio getting ready too?
I haven't made much progress on the Federal, but I keep thinking about it every day haha
Maybe it could be fun to pay you a quick visit at some point I get to be in the area. You know you are welcome whenever you want in Paris!
Cheers
ps: back to topic... your u73 is CRAZY. Keep them close up electronic porn pictures coming!
Thomas you are welcome to my building site any time! ???
My studio is years away, I have a wife who will see to that :'(
But the U73b is finished except for labels. 8)
The voltages are all spot on but it has to be calibrated and tested.
I will do that over the next week and post the results and graphs etc. then I'll ship it to Ruairi in LA. for him to play with.
Best
DaveP
My studio is years away, I have a wife who will see to that :'(
But the U73b is finished except for labels. 8)
The voltages are all spot on but it has to be calibrated and tested.
I will do that over the next week and post the results and graphs etc. then I'll ship it to Ruairi in LA. for him to play with.
Best
DaveP
Just a quickie before I post the results.
I think I have found another reason for the parallel resistor I posted about earlier.
Without that resistor, the diode output is such that it causes the compressor output to fall, rather than continue at a steady rate.
As there is no feedback path in this feed-forward compressor, the diode output must be perfectly calibrated against the input.
That resistor seems to cause "compression" in the TX which only affects the output linearity at high outputs, the low level signals have a linear response. When coming up to maximum levels the TX does not produce quite as much DC so the characteristic stays flatter. I think the engineers had to put the resistor in for that reason.
Best
DaveP
I think I have found another reason for the parallel resistor I posted about earlier.
Without that resistor, the diode output is such that it causes the compressor output to fall, rather than continue at a steady rate.
As there is no feedback path in this feed-forward compressor, the diode output must be perfectly calibrated against the input.
That resistor seems to cause "compression" in the TX which only affects the output linearity at high outputs, the low level signals have a linear response. When coming up to maximum levels the TX does not produce quite as much DC so the characteristic stays flatter. I think the engineers had to put the resistor in for that reason.
Best
DaveP
thomasdf
Well-known member
wow fascinating! thanks!
At last we have some results!
This has been a learning curve for me as it's the first feed forward Comp I've made and it has taken some time to get to know it.
It's a bit like setting up Windows without the built-in defaults, everything is variable so where do you start?
The calibration instructions in the manual are not detailed enough and the modern components in my version are sufficiently different, that the curves are shifted down from the original by 5dB, but are otherwise the same as you can see below.
If the controls are not properly set, then it's easily possible to make the gain fall so much that the curves instead of remaining straight, go negative ??? This is what happens if you just follow the manual, so I had to set up the output levels first and make sure that they stayed flat for the correct length and just let the linear amp section be whatever it turned out to be, and that is what the chart shows.
Although it's tricky to set up, there are no other artefacts to worry about as it's rock solid stable. Sometimes (often) feedback compressors can exhibit oscillation if the layout isn't perfect, but of course there is no setting up to do as the feedback type are self regulating.
Test Conditions and other data:-
Signal generator 600 ohms output Z
Input Impedance 20k
Output impedance 80 ohms
Tested with 600 ohm load on the output.
Signal to noise ratio as accurate as I can measure was:-
Hiss -78dB/Hum -70dB relative to +6dB output
These are all unweighted figures, with open input.
Frequency response to follow soon.
best
DaveP
This has been a learning curve for me as it's the first feed forward Comp I've made and it has taken some time to get to know it.
It's a bit like setting up Windows without the built-in defaults, everything is variable so where do you start?
The calibration instructions in the manual are not detailed enough and the modern components in my version are sufficiently different, that the curves are shifted down from the original by 5dB, but are otherwise the same as you can see below.
If the controls are not properly set, then it's easily possible to make the gain fall so much that the curves instead of remaining straight, go negative ??? This is what happens if you just follow the manual, so I had to set up the output levels first and make sure that they stayed flat for the correct length and just let the linear amp section be whatever it turned out to be, and that is what the chart shows.
Although it's tricky to set up, there are no other artefacts to worry about as it's rock solid stable. Sometimes (often) feedback compressors can exhibit oscillation if the layout isn't perfect, but of course there is no setting up to do as the feedback type are self regulating.
Test Conditions and other data:-
Signal generator 600 ohms output Z
Input Impedance 20k
Output impedance 80 ohms
Tested with 600 ohm load on the output.
Signal to noise ratio as accurate as I can measure was:-
Hiss -78dB/Hum -70dB relative to +6dB output
These are all unweighted figures, with open input.
Frequency response to follow soon.
best
DaveP
Dave,
How did you produce this graph?
How did you produce this graph?
Abbey,
I read the PTP figures off the scope, converted to RMS, then divided by 0.77459 for +dB and divided into 0.77459 for -dB.
I then put the figures into Excel like this:-
I just used the smooth line option which I had to adjust to get rid of the bumps that it makes.
Hope that makes sense
Best
DaveP
OK, that's what I fearedDaveP said:
Abbey,
I read the PTP figures off the scope, converted to RMS, then divided by 0.77459 for +dB and divided into 0.77459 for -dB.
I then put the figures into Excel like this:-
I just used the smooth line option which I had to adjust to get rid of the bumps that it makes.
Hope that makes sense
Best
DaveP
For a moment, I was madly hoping you had found an answer to this
http://groupdiy.com/index.php?topic=59404.0
Phrazemaster
Well-known member
Mind blowing build!! I'm so impressed! Wow!!!!
Loved the sharing about England and France and international issues too. I'm an American and looking to move to England as my father is Greek and I can get Greek citizenship (watch it with the Greece economy jabs please!).
This puts all my efforts to shame, but then again I'm more a musician and teacher than DIY guy.
Thanks DaveP; superb project and what an incredible contribution to the DIY community!
Will you be posting any more final build pix, and/or sound samples?
Thanks!!!))))
Loved the sharing about England and France and international issues too. I'm an American and looking to move to England as my father is Greek and I can get Greek citizenship (watch it with the Greece economy jabs please!).
This puts all my efforts to shame, but then again I'm more a musician and teacher than DIY guy.
Thanks DaveP; superb project and what an incredible contribution to the DIY community!
Will you be posting any more final build pix, and/or sound samples?
Thanks!!!
))))Thanks Phrazemaster, I do my best.
I hope the move to England goes well, there is a thriving music scene there. Your biggest problem will be finding affordable housing. So many houses were destroyed by the war that the rebuilding programme never really caught up with the immigration, so prices are sky high. It's a crowded Island. You can find cheaper housing away from train stations but then you will need a car! The taxation system is fully developed and unavoidable because it is deducted by your employer unless you are self-employed and the black economy is negligible, don't forget to drive on the left!!
I will be posting the frequency response and some final pics after the labelling is done, I have to fit this in around renovation of my new (old) house in France. The sound samples will probably be best provided by Ruairi when it goes to him in LA.
Best
DaveP
I hope the move to England goes well, there is a thriving music scene there. Your biggest problem will be finding affordable housing. So many houses were destroyed by the war that the rebuilding programme never really caught up with the immigration, so prices are sky high. It's a crowded Island. You can find cheaper housing away from train stations but then you will need a car! The taxation system is fully developed and unavoidable because it is deducted by your employer unless you are self-employed and the black economy is negligible, don't forget to drive on the left!!
I will be posting the frequency response and some final pics after the labelling is done, I have to fit this in around renovation of my new (old) house in France. The sound samples will probably be best provided by Ruairi when it goes to him in LA.
Best
DaveP
Phrazemaster
Well-known member
Awesome Dave!! Thx for sharing. Je parle francais un peu; do you like France better than England then?
