post #1321 of 2194
9/22/07 at 3:37pm
Any requests for tests/measurements of coupling capacitors, C177 bypass, DC bias, etc., on a SB-0460?
- SB-0460 Fatality 1 board is modded with Line-Out capacitor and Line-Out opamp sockets.
- will be switching to an Auzentech X-Fi Prelude in 2 weeks or so.
Soldering irons, eh?
- simple, low-cost "temp" controller for small, resistive element soldering irons. (about $6.00 USD for switch, diode and cord)
- when used with HAKKO N454, 25watt pencil, "low" setting for small parts and "hi" for work needing more heat. (ie., ground-plane connected caps)
- HAKKO N454 with stock tip has enough thermal mass, tip-shape and temperature to work with all X-FI level mods.
- quick "heat-up" and "heat-down." (about 3mins)
- purchase interchangeable tips to match your personal soldering technique or needs.
Usually leave in "low" setting for almost all work.
- "low" setting tip temp, idle: about 580f/304c
- stock Hakko N454 gets a bit too hot for my usual type of work. (~800f/426c)
- have not detected soldering defects using standard 60/40 or "lead-free" wire solder or paste.
- less bench space compared to stations.
- in use for about 3 years without issues.
HAKKO N454 Description and TIPS:
from the results,
1. frequency response +0.00 -0.03 vs. yours +0.01 -0.07, more superimposed for mine.
2. Noise level, -109.3 vs. yours -116.5
3. Dynamic range, 109.1 vs. yours 116.4
4. THD%, 0.0003 vs. yours 0.0007
5. IMD + noise, 0.0013 vs. yours 0.0009
6. crosstalk, -107.7 vs. yours -113.0.
1. mine has very lots of spikes in background noise around 50~60, 120, 160, 250~1k, beyond 25k. Your is very clean.
2. mine has very lots of spikes in dynamic range chart same as in noise level chart.
3. in HTD + Noise, the spikes in noise also contribute.
4. in IMD, the spikes in noise also contribute.
5. cross talk is higher than yours.
6. IMD swept almost the same.
In general, it seems all the noises contribute to this very bad results! Germanium, did you encountered the same thing after my steps of mods? If so, please advise!
Earlier next month, I'll do the further mods as you suggested. Hope will get better results!
Woa, IMD looking really bad & so is noise. Opamp is different from mine & i'm just bypassing with large value metalysed film on the powercaps. I didn't actually change opamps or power caps at all. You went way beyond my mods actually. I stayed there I was at due to the excellent results I was getting.
from spec, my opamp is the same as yours. I looked through my previous results for 24bit 96kHz, the spikes were already there, but after mod, more prominent for some. But the IMD (swept tones) was lower after mods.
I suspect for some of the spikes are caused by my very noisy pc psu and other PCI components.
I'll do further mods with bypassed caps with 22uf, 3.3uf and 6.8uf SOLEN ones in order to do some filtering of the power supply. (is that the filtering true?)
and replace all other stock caps with audio-grade ones. And shield the whole card with iron plate to see the improvements.
I'm using the stock NJM2114 opamp not the LME. Yes i do believe a lot of the noise is your power supply. The THD distortion is better on that so leave the opamp but work on the powersupply & return the 3300uf cap you put in there with the stock cap. Bichi has noticed that going to a very low ESR cap here is counterproductive without other changes in the circuit.
Thanks Germanium! I'll wait until all the mods are done to see if improved. If not, I'm going to replace my PSU to a purer one to see.
But sonically, I like the sound so far after my 1st mod hours before... much full in it, I like it.
I'm using HD650 directly with no amp.
Correction; talked to bichi today & appearantly the blackgate should be fine. It's the extreme low ESR of the Os-Cons that need the circuit reworking namely a different inductor. So just work on the PC powersupply.
"...also, what's that component in the attached picture? Another oscillator?? Thanks!..."
Germanium, I looked through some hi-fi forums, some modder are changing the crystal oscillators for some other cards.
I know x-fi is using a 2-pin 24.567MHz near DSP, maybe just around 50ppm precision. Do you have ideas to change to a more precise 2-pin/4-pin crystal oscillator?
also, what's that component in the attached picture? Another oscillator?? Thanks!
Germanium, thanks for your information.
Beside the 4 shorted caps, there are 2 left on the right, which are 25v100uf and 16v47uf, can you tell what are the functions of these 2 caps? A little bit more is expected!~ I'm now learning about the functions of capacitor, but no real examples...
How about the 2 25v220uf caps near the AD_LINK? Opamp power supply?