I believe that it was a very commendable efort by Joachim, Alfred, Frans To name just 2, to keep this open to evveribody so my 2 cents....
By the way many may be record listeners more than fricos electronic twidlers
So a voltmeter may be very limited epecialy in AC band width as one rather buy records than electronic gadgets.
(mine is not
but if she ever find out how much I have paid for it is going to be big badabang, yes I could have buyed one and half of the oscilloscope I have for same dosh and no me just mechanic compared to same experts we got here)For those there are quite a few cheap if not free oscilloscope programs
Virtinis Arta Truerta are just a few
One can just download the program and take measurement with the computer sound card
Yes is not going to be accurate but is going to be enough to confirm your listening test impressions
As I said in regard of channel balance, that apparently effect staging, as the input is common for both channels and provided that one calibrate the PC sound levels, one can measure the difference in gain, and repeat the listening test.
So one more reason to use a trim pot and twidle away while listening?
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I'm looking at it now. ;-) Sadly that doesn't give me the knowledge to know what to adjust on it.
MY most sincere apolologies I got the resistors numbers wrong as some how
R1 SCH came up
For Revision 3 the resistors I am refering to are R14 /R38 or R37/ R39
and with 100K maybe more pot on R19/ R20
And another thing how bad wuld be efect of mismatched Jfets Q97 Q98 and the 12 V ? zenners
10K multy turn across R27?
Vdrop there is caused by more current going troug ( Me think)
That also in R3 suply J fets and associated Zenners and those are known to be frivolus in respect to tollerance.
But again fishing in the dark....
looks like you have a huge imbalance somewhere. could you check the voltages across the emitter resistors of the input stage, to check if all transistors carry the same current?
this voltage should be below 200mV each (the exact value escapes me but they should be identical....)
If I remember there is help files on the download from the site but is prety intuitive on how to use.
No need for probes as it uses the sound card from the PC.
For measuring channels ballance is prety good but it can be made much better with a decent sound card I have Audiophile 192 but is prety old and internal (PCI) an external card with decent PSU wuld be less afected by HUM
as my set up doe's with noise floor at 50Hz around -70dB
http://www.diyaudio.com/forums/pc-based/220929-usb-soundcard-measurement.html
http://www.diyaudio.com/forums/software-tools/198428-need-help-choosing-sound-card-use-truerta.html
http://www.diyaudio.com/forums/equipment-tools/219632-winaudiomls-powerful-analyzer.html
The win audio mls is from look of it realy advanced the Demo version that one can have for free is limited but the full program can be had for £160.
I hope this can help you getting started abowe pointers are for ones that do not realy feel the need for oscilloscope so sound card may be worth Having any way...
This last link is for win audio mls they do sell and rent full solutions including sound cards and microphones
Have a look at prices and S.....T in your pants but have a look at prices for students and is a much better story once you have done that cek Ebay they have deals at very low prices altrought most of those are in the german Ebay site.
WinAudioMls: Audio Realtime Analyzer for Windows platform using FFT and MLS
Audio Spektrum Analyzer WinAudioMLS | eBay
I don't know about MAC possibly gogling up same of those sites wuld point you to right place.
What is Mac old mac? far to old 386 stuffNow seriously
Being MAC it may be a much faster better sistem but normaly one got to pay the price for proffesional gear whic is what MAC is (for best video editing software it leaves any windows based gear standing at the trafic lights)
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I kind of remember that Hesener did a design/article (maybe Elector?) for a interface
I kind of remember that Hesener did a design/article (maybe Elector?) for a interface
Worth me diggin up same more so link to that be great...
Still my apologies as this is gettin off topic
The idea at begining was to point audiophile to same free (altrought limited) test gear.
So back to topic any comments about my fishing in the dark expedition of earlier on.
What happens if one put a 10 k pot on R3 and R7 and twidle it?
Maybe I shuld ask one question at time I think
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