AU-999 Mystery components and power switch quesions

Oh bummer, The one on the right, which goes to the Molex connector on the end terminal is definitely the right one, so I must have seen it wrong coming from the right.....

Gotcha.. I'll get them switched. Did i mention how much i hate these tiny wires??
 
Can you take a picture and post......? We will be able to help....

If you trace one wire back, it will disappear into the front panel to the switch, and the other one will trace back to a pin on one of the blue molex connectors.....

One set of wires coming from the controls, one leads to the main in, and the other to the pre-out. Could I just remove the board and connect them all together?
 
One set of wires coming from the controls, one leads to the main in, and the other to the pre-out. Could I just remove the board and connect them all together?

Yes you could do that. I removed the board on mine.....:thmbsp:
 
It was broke when I started so I only used phones for testing.
When I bypassed the filter, I also added .1uF bypass caps on the main filter caps.
When I was checking it out after the repairs, I used small speakers at this phase of testing. But I know the source material intimately and these speakers have very good bass for their size. I heard good strong deep bass. We may be onto something here....

I was reminded of a comment someone made where the AU-999 doesn't really seem to need a loudness control. I questioned it when I first read it, but I was reminded of it when listening, and found myself agreeing with that thought.

I've developed a loudness circuit retrofit for my Franken 999 but haven't installed it yet. That will be interesting.

DcinDc: i am currently doing this, i just put a jumper on this pics that is described and put in .1uf bypass on the main filter? Does this apply to newly recapped unit?? what voltage on the bbypass caps? regular mylar caps??
 
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That's what I did and it sounded fine but I'll defer to Kev's knowledge on this. He said that it makes a filter of some kind when still in place like that. Yes, mylar bypass caps.
 
That's what I did and it sounded fine but I'll defer to Kev's knowledge on this. He said that it makes a filter of some kind when still in place like that. Yes, mylar bypass caps.


You can put the jumper in, just make sure you snip those resistors off, you do not want to be connected to those.
 
Just reviving this, I finally have some time to have a look at the subsonic filter removal

Did some before freq response measurements earlier today (this is from Aux in to Speaker Out, no filters etc switched in)


AU999freqresponse20hz1Khz_zps7a061301.jpg


Looks similar to what Kev posted a couple of pages ago. I'll post up the same graph once the filter is bypassed.

Cheers

John
 
Just reviving this, I finally have some time to have a look at the subsonic filter removal

Did some before freq response measurements earlier today (this is from Aux in to Speaker Out, no filters etc switched in)

Looks similar to what Kev posted a couple of pages ago. I'll post up the same graph once the filter is bypassed.

Cheers

John

Good stuff John, does look all too familiar doesnt it......

My measurement was through the pre-amp only, but I should think the poweramp would have a negligible effect on what we are measuring here.....
 
Ok,

Right channel subsonic filter bypassed -

AU999freqresponse20hz1KhzRCsubsonicfilterremoved_zpsbdee0695.jpg


I think that this concurs with your measurements Kev, and certainly shows the effect of the subsonic filter on low frequency response...... now to bypass the left channel.... and have a listen......

Cheers

John
 
Completed the subsonic filter delete mod this morning, and have to say that it somewhat transforms the amp with regards to bass response. I would recommend this mod to anyone who ha an AU999 with the subsonic filters fitted.

Some pics of the process I used (the mod could be accomplished a number of ways, this is the way I did it)

Right channel before the mod (one wire already removed)

AU999SubsonicFilterDeleteRightChannelbeforeonewireremoved_zpsec28a1f9.jpg


Right channel after the mod

AU999SubsonicFilterDeleteRightChannelafter_zps7afd8807.jpg


And the left channel before

AU999SubsonicFilterDeleteLeftChannelbefore_zps1b803c53.jpg


Left channel after

AU999SubsonicFilterDeleteLeftChannelafter_zpsf2e8116b.jpg



Cheers

John
 
Hi guys
when the ampli arrived the first thing was connected and play for reference a cd that I know very well (the dark side of the moon)
really a tank, wharm sound, but.......
shit! bass was zero!

So... five minutes and the ampli was naked.
I've cut the two tiny cables of subsonic filter, connected as you noticed and play again music.
shit(x2)! bass is still zero!

the au999 isn't famous for bass response, but this is too poor!
managing the bass pot on + 4/+6 at 100hz is bit better. But I need for the 20-100 band.

In the manual I can read under Control " BASS +12db / -8db at 20hz.
but there isn't any way to menage the 20hz! where is the control?



May be that he need of a total recap?
May be that I use to listen music with valves ampli (a simply rogers cadet III) ?

Please any idea. I'm really frustated
ciao!

Rug
 

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Hi guys
when the ampli arrived the first thing was connected and play for reference a cd that I know very well (the dark side of the moon)
really a tank, wharm sound, but.......
shit! bass was zero!

So... five minutes and the ampli was naked.
I've cut the two tiny cables of subsonic filter, connected as you noticed and play again music.
shit(x2)! bass is still zero!

Are you sure you have the subsonic filter block removed correctly?
But even then, that is only the beginning of the journey to make the AU999 a great performer.
I highly recommend you do the pre-amp modification. It brings the whole sound of the amplifier into another level of performance. You can read at the end of the thread a few guys did it and love it....
Check the thread here..
http://www.audiokarma.org/forums/archive/index.php/t-466545.html


the au999 isn't famous for bass response, but this is too poor!
managing the bass pot on + 4/+6 at 100hz is bit better. But I need for the 20-100 band.

In the manual I can read under Control " BASS +12db / -8db at 20hz.
but there isn't any way to menage the 20hz! where is the control?

May be that he need of a total recap?
May be that I use to listen music with valves ampli (a simply rogers cadet III) ?

A re-cap may help a little, it is hard to say without knowing how bad the caps in the amplifier are.

The tone controls are a bit shit on these amplifiers, especially the bass control.
The "centre frequency" for the bass control regardless of whether you have 200hz or 400hz selected, is 20hz.
This means that 20hz is boosted 12db when the bass is set to maximum.
The 200hz and 400hz is determined by a capacitor which controls the width of the boost/cut from the 20hz centre frequency, and if I remember correctly, the boost of 200hz when the control is set to maximum is only +6db.
But because this control is a Shelving filter, the frequency goes from 200>20hz or 400>20hz depending on which is selected.
The slope is too gradual, you cannot get enough of the "right bass" before you have the unwanted frequencies coming through.
This tone control (bass) is actually pretty much useless in my opinion.

I have modified mine, I have made the "slope" a lot steeper than factory, and increased the response.
I get +12db at 100hz now if I want it, which is a much more useable area of bass....
The slope is a lot more steep, more like what you would find on a professional mixing console, which is what I am used to.
I will post some pictures of which resistors to change, and the values of resistors to do this.
But you will need to modify the preamp as in my other thread, otherwise the pre-amp will not have enough headroom to handle this mod....
I may be able to do this over the next few days.....
There is 4 resistors to change to do this, it will take about 10 mins..

I can tell you, that this mod is brilliant, you will have all the bass you want, and more......

Hopefully you can understand my English enough to get the idea.....

I will post this in a new thread...
 
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