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

[maniac]

My report in regards to my issue described above (quiet hiss about at 900hz) which i've got after applying Muratas which I had then partially fixed by applying 220uF caps .

Today I've shortened power cable between original Caiman PSU to Caiman to about 40cm (15,7") and removed 220uF caps from Muratas. My hiss issue is completely back so there is something weird on it as shortening path between PSU and Muratas should be solution instead of caps workaround I've done before.

I'll let it in this state until cheapest laboratory linear PSU will arrive and i'll test it with this PSU. If this linear PSU will not help I think unfortunately will have to go back to caps on Muratas..
And probably will xperiment with different caps values as 220uF did not removed the hiss completely.

[chapter three]

Just a quick question, I hope this isn't thread crapping ..

I've got a Caiman/Gator with no other mods. What benefits would I get from fitting Elna, Muratas and rubycons etc?

I'd ask Tirna to do the work. I use a Maplin linear supply tweaked to 15v as mentioned on here.

I'd like a bit more bass weight from the dac. Would the modifications I'm considering help?

[StanleyB]

It would help, but you'll need to add the Gator board for the final finish.
Tirna is actually trying out the Gator board to see if they can offer a Gator fitting service with their other upgrades. It would save on the cost of shipment etc. in some cases.

[StanleyB]

The standard Gator is designed to be all things to all headphones, but I left some blank component spaces in the PCB so that the Gator can be tuned to various cans.

The following is a tune up for my K701. The added caps in the middle next to the 22nF ( 47nF in the standard board) are 220pF. So you need 2 x 22nF and 2 x 220pF. It gives the K701 a lot more weight and body.

[StanleyB]

The Gator headphone output has been set to a level that can cope with a wide range of headphone impedances. However, cans like the HD600/650/800 and some Beyer Dynamics versions with their 300 or even 600 Ohms impedance are able to take advantage of an up to now undocumented feature of the Gator PCB.

The resistors marked with a red circle are 42K instead of the standard 27K fitted to the Gator. You could even go up to 56K but sound clipping will occur at high volume levels. Mind you, at that sort of level you are likely to go deaf very quickly.

This mod is for educational purposes and information only. You should not listen to your headphones at these sort of levels since the headphones will be banging against your skull from the extreme air movements induced by the transducers. And you can go deaf on top of it.

[maniac]

This mod is for educational purposes and information only. You should not listen to your headphones at these sort of levels since the headphones will be banging against your skull from the extreme air movements induced by the transducers. And you can go deaf on top of it.

Hi Stan, many thanks for sharing, my questions:
1. What are the benefits of this mod? Is it only having my hd800 headphones playing louder?

2. marked resistors on your photo are 42kOhm ? I'm not sure if i'm reading the strips correctly but I think it's some think else than 42kOhm (412*10 at 1%) ?

3. it wattage of resistor important, or I can safe use let's say 1Watt resistor?

Sorry for lame questions, I'm still re-learning what i've learened 15 years ago

Thanks,

Tomas

[StanleyB]

1. As indicated: it is to increase the output level. If you want other benefits as well you'll have to fit the corresponding mod if and when available. So if you want more bass drive, then look at the K701 mod since the HD800 is just as demanding as the K701 before they put out any decent amount of bass.
2. I wrote 42K and that is what should be fitted . I personally use a range of resistor E values for R&D, but which are not normally on sale in Maplin etc. So I mention the nearest equivalent that you can readily source and buy.
3. Use the same size as in the picture if you want to make sure that it fits. 1W might be a bit longer. 0.4W would be about right in size.

[maniac]

My report in regards to my issue described above (quiet hiss about at 900hz) which i've got after applying Muratas which I had then partially fixed by applying 220uF caps .

Today I've shortened power cable between original Caiman PSU to Caiman to about 40cm (15,7") and removed 220uF caps from Muratas. My hiss issue is completely back so there is something weird on it as shortening path between PSU and Muratas should be solution instead of caps workaround I've done before.

I'll let it in this state until cheapest laboratory linear PSU will arrive and i'll test it with this PSU. If this linear PSU will not help I think unfortunately will have to go back to caps on Muratas..
And probably will xperiment with different caps values as 220uF did not removed the hiss completely.

OK, so some news here. Laboratoty PSU HY1503D</a> arrived (priced at 50 eur) with parametes defined as:
Source Effect (Line regulation): CV <= 0.01% +1mV CC <= 0.2% +1mA
Loading Effect (Load regulation): CV <= 0.01% +3mV CC <= 0.2% +3mA
Ripple and noise: CV <= 0.5mV V r.m.s. CC <= 3mA r.m.s.

(If i'm reading correct it's quite fine in the specs. for the Caiman)

As usual I have some news:

Bad news - Hum/hiss at about 900Hz I described few times in this thread is still there (from the time i've upgraded to Muratas and Elna)

Good news - I'm able to get rid of the hum/hiss by setting specific voltage:
- lower than 13V
- exactly 13.3V or 13.4V (but seems not to be stable here - hum/hiss comes back sometimes, so i go for 12.9V at the moment)

Findings:
- I have not seen any difference in relation of length of power cable (either original Caiman PSU nor Linear supply) to my hiss issue.
- I did not hear any difference on quality of sound reproduction on voltages lower than 15V (12 to 15V).

So I'm now powering Caiman with 12.9V to avoid my hiss issue, unfortunately this is sometime (with Caiman not yet "warmed-up") causing my source input on Caiman returning back to USB (I'm now using Coax1 for SB Touch). I understand that Caiman is designed for 15V but for the moment I rather wait a bit to warm-up Caiman until I can start listening than to listen to constant hiss on the background..


As have some new facts about behavior of this issue (apparently related to Caiman input voltage) I would like to ask if someone have a clue what could be the source of my 900Hz hiss? Does this seems like fried Muratas when I was modding the Gatorized Caiman?

The frequency is slightly going up and down when slowly regulating the voltage on PSU or changing bitrate of source signal between 44 an 96kHz.

Measurement of Voltage on Muratas I've done some time ago with original PSU can be found here:
12V reg: input=14.76V output=11.98V
5V reg: input=14.75V output=5.00V
http://theartofsound.net/forum/showp...2&postcount=35


Analysis of three signals:

green = original wav file with pink noise generated in Audacity
cyan/blue = pink noise signal recorded on MBpro from Gatorized caiman and linear psu set to 12.9V
red = pink noise signal recorded on MBpro from Gatorized caiman and original Caiman PSU with shortened power cable to 20cm - you can see the spike at abut 900Hz and a tiny bit higher noise in area under 20kHz in comparison to linear PSU

fullsize pic:
http://localhost.sk/dropzone/linear_...gr%5D-FULL.png

[mervinb]

The Gator headphone output has been set to a level that can cope with a wide range of headphone impedances. However, cans like the HD600/650/800 and some Beyer Dynamics versions with their 300 or even 600 Ohms impedance are able to take advantage of an up to now undocumented feature of the Gator PCB.

The resistors marked with a red circle are 42K instead of the standard 27K fitted to the Gator. You could even go up to 56K but sound clipping will occur at high volume levels. Mind you, at that sort of level you are likely to go deaf very quickly.

I am a proud owner of a new Caiman+ with Gator -- thanks Stan for the very fast turnaround. First impressions are very even performance with no obvious weaknesses.

One thing I noticed was that the volume (fixed output) of the Caiman with Gator is lower than my other dacs. Does the 42k resistor mod affect the fixed line out also, and my how many dB? I'm looking to a mod to increase gain sometime after my Caiman has bedded in.

[Werner Berghofer]

One thing I noticed was that the volume (fixed output) of the Caiman with Gator is lower than my other dacs.

I’m not able to compare my gatorized Caimans to DACs from other manufacturers, but the fixed line out volume of this model definitely is louder than the volume of Stan’s TC-7520 and the Caiman without Gator PCB.