Hi ,
The boards follow the same design as the the 2sw-1 & 2 . I did build the DD amp for the model IIIs just over 10 years ago with a tube front end. I have no plans to redesign the 2sw amps I am working on.
Unfortunately, I am experiencing oscillations in both amps and am working through it now. Its been very frustrating!
The boards follow the same design as the the 2sw-1 & 2 . I did build the DD amp for the model IIIs just over 10 years ago with a tube front end. I have no plans to redesign the 2sw amps I am working on.
Unfortunately, I am experiencing oscillations in both amps and am working through it now. Its been very frustrating!
I don't know of anyone.. Curcio still lists a refurb of the amps or a total re-design - but, I don't know how current that is. The amps are not that complicated in terms of layout. However, I am discovering they are very fussy. I had thought I was on a path to complete mine but I am having some oscillation problems at full voltage in..... You have to give them pretty good respect when trouble shooting so things are not as quick as are conventional amps.
Yes they are fussy. I also had problems when I did work on the amps once. I placed new caps, for space reasons, in between the small and big board which caused oscillations. I talked to Modjeski about that.
I got an email reply from Curcio stating he still can work on the amps but he seems very slow replying and I am hesitant to have my amps sent from eu to us. Mine work flawless
I got an email reply from Curcio stating he still can work on the amps but he seems very slow replying and I am hesitant to have my amps sent from eu to us. Mine work flawless
You are lucky your amps are running .. I would not change them and ship them across continents. If you have any advice on curing the oscillation I am interested.
Regarding the DD for the model 3's of course they run at a lower polarizing voltage than the 2's - for my purposes I used a simple 1st order crossover cap on the input to pass about 70khz and up to the panels ... everything else is sent to a pair of REL subwoofers. There is no eq otherwise. I tried electronic crossovers but I did not like that it imparted some loss of resolution to the overall presentation.
I am not giving up on the 2's yet. !
Regarding the DD for the model 3's of course they run at a lower polarizing voltage than the 2's - for my purposes I used a simple 1st order crossover cap on the input to pass about 70khz and up to the panels ... everything else is sent to a pair of REL subwoofers. There is no eq otherwise. I tried electronic crossovers but I did not like that it imparted some loss of resolution to the overall presentation.
I am not giving up on the 2's yet. !
Hello to all the guys working on the OTL amps for SW-2 :
My upgrade sounds very promising with lots of high end micro dynamics and big analoge sound !!
I have a problem with white noise (HQ Swing) after replacing the XO board with a Jean Hiraga design upgrade. All new caps in the driver board has also been installed.
Does the old XO board have any kind of anti HQ oscillation that I have missed ?The old design also have an IC circuit but I dont know what it does ? It seems that the noise are beeing transmitted to the other speaker as well as a HF transmitter.
When i touch the chassis on the outside the noise goes down.
Grounding are done on the driver board only.
The wires inside are also supplyed with ferrite perls everywhere.
I have put 82 PF in parallel over the out put transistor in the driver bord, see attached file. This stabilize the circuit a lot but it affects the sound quality.
The white noise goes almost away after 1 hrs warming up, but occurs only" like dust on the cartridge " in the dynamics ex piano midrange.
Hope for som input
I´m not giving up on this ....yet !
BR Bjoern from Denmark
My upgrade sounds very promising with lots of high end micro dynamics and big analoge sound !!
I have a problem with white noise (HQ Swing) after replacing the XO board with a Jean Hiraga design upgrade. All new caps in the driver board has also been installed.
Does the old XO board have any kind of anti HQ oscillation that I have missed ?The old design also have an IC circuit but I dont know what it does ? It seems that the noise are beeing transmitted to the other speaker as well as a HF transmitter.
When i touch the chassis on the outside the noise goes down.
Grounding are done on the driver board only.
The wires inside are also supplyed with ferrite perls everywhere.
I have put 82 PF in parallel over the out put transistor in the driver bord, see attached file. This stabilize the circuit a lot but it affects the sound quality.
The white noise goes almost away after 1 hrs warming up, but occurs only" like dust on the cartridge " in the dynamics ex piano midrange.
Hope for som input
I´m not giving up on this ....yet !
BR Bjoern from Denmark
Attachments
Hello @Bmalskr
Does this noise exist if you go back to using the original crossover board? Most users disband using the original crossover board because better solutions now exist for self powered subs-- I have abandoned this board. The IC chip is a quad op amp used for cross over.
It is definitely oscillation- I am experiencing the same effect "white noise"that you describe on my pair. Have you looked at the output with a high voltage probe on what would be the electrodes "red" and "black" --- it is quite obvious on the scope.
I have not been able to pin down the oscillation- I am getting some advice from an experienced member hear that is trying to kindly help over long distance.
I am just wondering where the source of the oscillation is... It is a difficult circuit to manage because of the HV... Can you observe oscillation without the HV taps to the board connected on the input board alone. I know you can only get so far- because of the feedback required by the 7.5M resistors but it would be interesting to see how far on the input the signal is clean.
My suspicion is that its happening on the HV side and being fed back
Have you changed your transistors from original - if so to what?
Where exactly have you placed the ferrite beads?
Let us know!
Does this noise exist if you go back to using the original crossover board? Most users disband using the original crossover board because better solutions now exist for self powered subs-- I have abandoned this board. The IC chip is a quad op amp used for cross over.
It is definitely oscillation- I am experiencing the same effect "white noise"that you describe on my pair. Have you looked at the output with a high voltage probe on what would be the electrodes "red" and "black" --- it is quite obvious on the scope.
I have not been able to pin down the oscillation- I am getting some advice from an experienced member hear that is trying to kindly help over long distance.
I am just wondering where the source of the oscillation is... It is a difficult circuit to manage because of the HV... Can you observe oscillation without the HV taps to the board connected on the input board alone. I know you can only get so far- because of the feedback required by the 7.5M resistors but it would be interesting to see how far on the input the signal is clean.
My suspicion is that its happening on the HV side and being fed back
Have you changed your transistors from original - if so to what?
Where exactly have you placed the ferrite beads?
Let us know!