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Old 25th December 2009, 07:42 AM   #511
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"What have they done with my song" was the song I meant. Nice.

The IA will take some time, anyway.

Rüdiger
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"I can feel what's going on inside a piece of electronic equipment. I have a sense that I know what's going on inside the transistors." Robert Moog
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Old 25th December 2009, 09:53 AM   #512
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Ok, i am looking forward to it. Itīs not an easy circuit i know but i wanted to look into instrumentation amps and symmetric RIAA too. In fact i made a commercial Phonoamp based on Instrumentation priciples that worked well. It had extremey low distortion and was very imune to hum.
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Old 25th December 2009, 10:07 PM   #513
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Here is a photo of the TDSF taken with my cell phone.
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Old 26th December 2009, 12:07 AM   #514
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Today i talked to Siegfried Linkwitz and he was wondering how i did a 6th order filter with only 4 capacitors. Well, again i simulated the TDSF over a 100dB dynamic range and yes ! he is right. Itīs a forth order sub Linkwitz response with constant group delay.
But still itīs -60dB down at 2 Hz and i think itīs efficient. I liked the subjective result so much that i will keep it that way.
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Old 26th December 2009, 12:41 AM   #515
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I did more listening today. For the first time i combined my finest DIY efforts, the MPP low Z Led, the inductive RIAA and the PSG Buffer with Alps studio faders. I had experienced a slight loss in bass slam before with the PSG (due to power supply issues i think), so i raised the level of my sub by 0.5dB and lowered the crossover somewhat and the result was :
MAGIC ! Talk about transparency ! I had tweaked the inductive RIAA slightly and it is now dead accurate at my + - 0.1dB measurement limit from 20 to 20kHz. I generate the RIAA curve mathematically so no problem with tolerances in passive anti RIAAs.
Both channels are absolutely the same now in shape and volume. The Alps sliders come really handy because i found that very often the image is of center in many productions.
Mostly slightly on the left. I speculated that can be because most people are right handed or is it because we have the heart on the left side ? I do not know but itīs a fact. Tweaking the balance for each record gives a much better focussed image in my experience. Again i listened with my 16 year old son who has still hearing to 20kHz. He is not a big party animal so his exposure to load music is limited to a minimum.
This time we focussed on well recorded material. First was Belafonte at Carnegie Hall. A recording from 1957, 52 years old as me. How they did that recording is a miracle to me.
There is no audible tape hiss and a huge amount of micro detail on the German ARS Reissue that i had overseen BEFORE Classic Records entered the szene. On Cotton Fields i could hear the acoustic bass on one side and a LOUD echo on the other side ! amasing.
Next was Wonderful World with Luis Armstrong recorded in 1968. Not as clean as the Belafonte but extremely emotional and moving. When he was singing of a baby crying i may have glimpsed a little tear in my sons eyes. Do you know Valery Carter ? She made an amassing sounding solo album "Wild Child" in the 70th. She was there in the room, no question. Even a kitsch song like "Da-Du-Randevouz" came over as a work of Genius, kind of uptempo modern country, very danceable. Of cause Donald Fagen sang our hymn
"IGY". Then came Tina Turner with "Edith and the Kingpin" on the Herby Hancock Joni album. After that the original from Hissing of Summer lawns, still unmatched in my opinion and the sound was good from a Speakers Corner Reissue. They did a god job but added some bass in comparison with the original German pressing that still has the edge in freshness. Then Patricia Barber "Spit" on an Alto Remastering. I felt like in Rio and Chicago the same time. Weird ! and so it goes .........
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Old 26th December 2009, 08:08 AM   #516
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Thank you very much for your efforts Joachim!
I'm looking three times a day, if there is sth. new on this thread.
I have 2SC3329GR and 2SA1316GR at home, for the second stage of the MC part I would use 2SC1775E an 2SA872E. Luckily there are 4 OPA637 left for the RIAA Stage.
My question is about the 25mH coils. can you tell me a supplier?
The coils you use in the PSUof the MC part are 900mH with 166 R serial resistance?
And the other question is, do I need the servo, when I use the TDSF?

Appreceating your work and again thanks for your efforts

Sam

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Old 26th December 2009, 12:00 PM   #517
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Hello Sam ! the parts you choose should work. I tried the 2SC3329 and 2SA1316 in the Rositer and they are as good as the ROHMs. I did not try the 2SC1775 and 2SA872 but any decent low noise low level transistor with a high and straight Hfe curve should work here. The OPA637 are still very good. I use them as a distortion magnifier in my measurement setup.
It was planed to use 900mH coils but after i got the 25mH coils for the RIAA i used them too in the power supply and decided that they are big enough. Implementing them inproved the sound a lot : cleaner and more transparent. You can buy the coils from me. A single coil costs 10,-€ plus shipping. Tolerance is 5%. A pair of coils selected to better then 2% costs 50,- € plus shipping. They need some shielding (Mu Metal) or you can get a low level hum.
I did not use a servo in the TDSF. The offset was quite high with 30mV on both channels due to the poor DC precission of the NE5534 but no problem in my system because i have a cap in front of the poweramp. When you use Fet opamps like OPA134, OPA827 etc. offset should be under 1mV. If you like bipolar more something like the LT1468 gives good DC precission too.
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Old 26th December 2009, 01:29 PM   #518
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i looked up the data sheets of the transistors you will use in the second stage. They should work fine. Gain linearity is a bit better in the BC550 and BC560 ( they are exeptional in that regard) but the ones you coose have very high Hfe and bias is well controled in the MPP low Z Led. To see Hfe over 1000 is rare in non darlingtons. Noise should be fine too. I whould select them for Hfe for lowest offset.
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Old 26th December 2009, 03:19 PM   #519
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Default MPP Inductive 2.0

I think i had a good idea. The 75usec EQ could be done right in the Headamp with transimpedance and then C1 could be saved. That should have a performance advantage. If i find enough parts at home i will try it this evening.
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File Type: pdf MPP Low Z Led RIAA Inductive EQ xmas 2.0.TSC - TINA.pdf (79.0 KB, 116 views)
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Old 26th December 2009, 08:59 PM   #520
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Default last post

Some issues came up with DC offset when i build the circuit in my last post.
I solved the DC issue but then the servo influences the RIAA. I am working on the problem, so stay tuned.
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