Gator aid. Or how to get the most from your Gator.

[StanleyB]

1. Gator pcb board - replacement of 47nF capacitors with 68nF WIMAs

The HD800 is quite sensitive to cap mods. The 68nF might make the bass thinner. I would stick to the 47nF value.

[Heady]

...
Headphone users with Caiman & Gator:
The AD826 wins on all accounts so far. No messing about with special adapters (i.e. THS4032 ) or bending pins ( i.e. LM4562HA).

Does anyone know where I can purchase a couple of suitable type AD826 in the UK?

... Changing the gain on line out and headphones:
I'll come back to that at a later stage if there are sufficient interest. The current output levels are designed to be within the CE limits, but the line and headphone output especially can be adjusted for a different optimum gain setting, depending on the impedance of your headphones. ...

I'd like to tender my interest. I have two Camians - one with a K701 and the other with a DT990Pro and I'd love to fine-tune the gain for each.

[StanleyB]

Does anyone know where I can purchase a couple of suitable type AD826 in the UK?

I have the AD826 in stock and can ship the Gator with them upon request.

[Heady]

I have the AD826 in stock and can ship the Gator with them upon request.

OK - have sent an email to ask for two AD826 to be added to the current order.

Thanks

[maniac]

I've modded my Caiman with Murata regs and Elna Silmic caps two days ago.

After first scary moments with random clicks/pops (like from dirty vinyl) in right speaker i found out that optical connector (toslink-3,5mm jack) at Toslink cable was the problem - replacement of connector fixed the issue

On the other day I've noticed that listening to quiet music passages at considerably high volume levels reveals strange humming/squeaking tone at about 964 Hz . I found this tone on headphone signal output an also on fixed line signal output.

I've checked all work I've done during the mod and also checked if there is no lint from freshly soldered regs & caps - but found nothing important.

Then I tried to replace Gator module with original Caiman module and 964Hz humming disappeared. I've then also tried to use other opamp in Gator but also with original Caiman opamp humming was still there.

I've tried also different inputs (toslink from imac, spdif for Nad dvd player) - no change.

Tone frequency is bit different on 96kHz sample rate sources as on 44.1kHz .

I'm not sure what's causing this tone on background but surely would like to get rid of it as I like Gators sound much and would not like to go back to original Caiman module.

Here is picture analysis (recorded 24bit@96kHz with macbookpro) of very quiet pink noise i've created for testing purposes in audacity:



On request I can share wav/flac recording of pink noise output of my gator with this anomaly recorded.

My thoughts:

1. I've broken something during modding, but then I can't understand why the sound is there only with Gator?

2. This is normal "feature" of too revealing Gator and I just haven't noticed it before. I mean revealing weakness of Wolfson DAC or so.. Remember it's possible to hear it only on very high volume levels..

Any ideas?

[Stratmangler]

Any chance of resizing that image ?
The script is far too wide as a result of that image being too large, and most folks would just pass your question over, just as I have done.

Thanks in advance......

[maniac]

Any chance of resizing that image ?
The script is far too wide as a result of that image being too large, and most folks would just pass your question over, just as I have done.

Thanks in advance......

Hi Chris I've just resized the image, thanks for the notice. I hope this will encourage people to help me out of my troubles

Original image still can be found here:
http://localhost.sk/dropzone/Screen%...%20PM.orig.png

[dthp]

Hi Maniac,

I came accross the same troubles few weeks ago when modding my caiman.

I both use passive output and headphones output.
I upgraded the dac to murata regs + elna caps.

There was no problem with standard opamps used for standard module.
but as soon I upgraded to burson audio discrete opamp for heaphones output, I got a horrible "eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee" sound at high volume, I could easily hear at mid-volume.

I first tought it was the burson generating this noise, but I tried to turn the volume up with my loudspeakers and I has the same high pitch noise.

I read the murata 7805SR-C datasheet and saw:

Applications in which 78SR regulators are located more than 24 inches (61cm) from the input power supply should include an external 47uF/50V (or greater) aluminum electrolytic capacitor, connected as close as possible to the regulator’s +Vin and GND terminals (pins 1 and 2).

It's the case since I made a -15V/0V/15V linear regulated power supply, and the cord is 70 cm long.

The reg was actually ringing! As soon I put a 330µf cap between V input and ground, the noise stopped. I've not detected any troubles with the 7812SR-C yet, but if any, the fix would probably be the same.

I'm not sure it is the same issue, but I hope this will help you.

Anthony

[maniac]

It's the case since I made a -15V/0V/15V linear regulated power supply, and the cord is 20 cm long.

The reg was actually ringing! As soon I put a 330µf cap between V input and ground, the noise stopped. I've not detected any troubles with the 7812SR-C yet, but if any, the fix would probably be the same.

I'm not sure it is the same issue, but I hope this will help you.

Anthony

Hi Anthony, thanks for your answer in 1st place.
I would like to clarify few details - in Murata 7805 datasheet they say more than 60cm and you have only 20cm long cable so I'm quite surprised this was the case.
On other hand when i was trying to touch different parts on PCB it was exactly the muratas which changed a bit a pitch of background tone so it would make sense that they are responsible for the tone as such. I'm using standard PSU which came with Caiman.

May I ask what 330µf cap have you used (max voltage / temperature) and how did you soldered it? Like directly soldering it to Muratas pin, or some other way? Maybe you have photo saved somewhere?

And my last question - how would you describe benefit of having Burson's hd audio discrete opamp instead of originally fitted opamp for headphone stage? I was thinking about exactly the same but Stan did not reccomended that BTW i believe that you was not able to fit Burson into Caiman so you left upper lid of Caiman open?

Thanks, maniac

[dthp]

My mistake, it's 70 cm long, corrected in my previous post (I definitly have to read my posts before sending them).

I soldered a spare 330uF elna silmic II 25V ( but 16V will be fine), soldered directly the first reg pin and ground of the output cap. I must confess I'm not sure it is the root cause of the problem, as I am not a electronics expert, but adding this cap solved the problem for me.

Here is a pic:



For the burson, I think M. Beresford didnt recommand using bursons in its dac because they need -15/+15 power supply to work properly. I made a separate PS for it, that's why I use it in the caiman. The Burson is plugged in the socket using a bent extension, so the lid is closed. It was actually used in my previous dac, and I couldn't stand not using it in the beresford.

Here is a pic:



If you tried the passive output mod, I would say that the burson as headphone opmap brings the headphones output to nearly the same level of truth / dynamics / impact / lifelike reproduction, but that's just my perception trough my own ears

Anthony