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Posts by duncan1

I would disconnect what you have already soldered  that should leave a "live " and  an earth connection (screen ) on each . Borrow an AF signal injector  and connect to each cable that goes to your drivers in turn . It should sound  equal on each side at  1 kcs  then try at 5kcs  it still should be the same on each side . What can happen in Stax cables are that they disconnect internally and nothing shows all it takes is a sharp tug . If after testing it still doesnt sound...
Its possible that I have not put a concise rely to Fuzzzy . When I say the latest feed-back I am referring to my own modifications to as detailed in previous posts above .The Stax corps had a "brainwave " to remove most if not all feedback from its 727 to make it more open in practice this wasnt the total success that it hoped . It was instigated when the UK hi-industry went through a -"no feed-back is good" policy  I have re-instated with mods the original 727 layout...
I realise most people like the latest Stax but not everybody ,it was aimed at them. But ,yes you can have too much detail as it gets in the way of the music ,as you are listening to the detail not the music .I speak from a UK perspective as most of the "golden ears " over here come down pretty strong on it and its probable that US users like a different balance accenting the higher frequency range. Each part of a high -fi system adds or removes highs or lows to a small...
Hello fuzzzy if you have had many years of electronic service then you will know about primary feedback and secondary feedback-aka nested feedback . Everything I have stated I carried out myself on the 717 and 727. Electronics isnt some black magic anybody can do it if they read up on it and that is my whole point the inside of a power amp/pre-amp shouldnt be beyond the capabilities of the ordinary person .If they read books go to college/night school etc they soon learn...
There are many who like extreme detail both with the amp and the headphones but that does not apply to some who like a smooth musical presentation. It might not appear to some that the 717/727 boards are not really much different ,the main thing being the twin output devices on the newer board as compared to the original but the circuit of the newer board still has its original circuits still in place (except for the output circuit) . The openness and highly detailed...
I noticed some people have trouble adjusting the balance and near zero voltages  I do not think that the ones fitted are up to the job considering the price of the total unit. To make life easier and up grade them I fitted Multi-turn presets .These allow a much finer adjustment of the voltages . They are not the large volume control types as found in high end test equipment but much smaller and narrower 1 inch and a quarter long - 3 eighths height-3 sixteenth broad made...
I had forgotten to add that the feedback resistors total 300K OHMS in the unmodded version . If you check the circuit diagram you will see that it is a     version of a widely modded standard circuit. All the other versions show the series resistance as 200 K OHMS from the output to the input I had already reduced the series resistance to 200K OHMS using a parallel resistor across one of the 150KOHMS feedback resistors in the original circuit that means that 2 resistors...
Just a word to say I have added a stabilized  power supply using a mos-fet power transistor It is not an original design by me as there is a limit in the number of variations in solid-state design unless you make some specialized overload cut out. I used a constant current design which was pretty simple. Mos-fets are much more reliable in solid-state power supplies when used as pass transistors many normal transistors(BJT) need a lot of protection to stop them failing...
Of the working voltage of electroyltic caps that Cyril tested he found the lowest distortion on the 35 V range. Remember his own designed and built "cutting edge"[at the time ] but still good at =0.00001 % dis ability to display - Capacitors help in a specially designed jig to test with DC current flowing through them just to make thing    not only more harder but more to the point testing under near working conditions. Cyril published a series of articles on EE spread...
When my AVO VCM -tube tester went faulty till I fixed it I thought that was a temporary test   Many people have tubes that  are S/C internally its a common problem even with good make tubes. Instead of throwing then all away you could try a high voltage pulse across the S/C this sometimes "blows" the short off. You cant keep doing it as eventually it destroys the elements inside but it is always worth a try. Circuits can be seen on old tube radio repair sites. But due to...
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