I have already tested rmaa and the resault are good. I'm curious why when I connect the signal cable there are schowing noises on the chart (last one screan). When I connect a very short signal cable the noises are on the lower level. Without signal cable spectrum is quite flat at -130dB, just like in rmaa test.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Next one measurments (this time using Audigy1):
Load 8R
out 10V
ver with 2n5551/5401
ver with mpsa92/42
Now bias is 200mA, it is much better with higher bias (two pair output dev). I must work on my meas system, now it looks like chaos. Low freq products may be are result of my PSU, I'm not sure.
Load 8R
out 10V
ver with 2n5551/5401
An externally hosted image should be here but it was not working when we last tested it.
ver with mpsa92/42
An externally hosted image should be here but it was not working when we last tested it.
Now bias is 200mA, it is much better with higher bias (two pair output dev). I must work on my meas system, now it looks like chaos. Low freq products may be are result of my PSU, I'm not sure.
Something is very wrong with 2n5xxx version, the high order distortions are too high, like the bias is not correct. Have you measured bias in vas ? (Measure r15/17) Also 3rd harmonic is too high, it should be 10db lower at these power levels. (Might be signal source as both amps show the same) You could try using a CD-player as signal source, simply burn some test signals on cd.
With these distortions for the 2n5xxx the mpsa version must sound better. The mpsa version looks much more like it should be.
Mike
With these distortions for the 2n5xxx the mpsa version must sound better. The mpsa version looks much more like it should be.
Mike
The bias values are fine for both. No idea what's wrong with the 2n' version. Could you "simply" replace the 2n's with mpsas in the other amp ? (Or the other way around) Maybe something else is wrong. It could be the drivers.
Have you checked the 3rd harmonics for the audigy with RMAA ?
Mike
Have you checked the 3rd harmonics for the audigy with RMAA ?
Mike
Hi Mike,
I just bought a Soundblaster X-Fi ExtremeMusic. It's supposed to record from 10 Hz to 88 KHz (!), see here http://www.creative.com/products/product.asp?category=1&subcategory=208&product=14066&nav=1
I just hope I can get my computer to recognise sound cards again. Then I'll run some tests on it and let you know.
-Chris
I just bought a Soundblaster X-Fi ExtremeMusic. It's supposed to record from 10 Hz to 88 KHz (!), see here http://www.creative.com/products/product.asp?category=1&subcategory=208&product=14066&nav=1
I just hope I can get my computer to recognise sound cards again. Then I'll run some tests on it and let you know.
-Chris
No way. A/D is 24/96 max, so there won't be anything beyond 48 kHz. The D/A-section is claimed to do 192 kHz, but that doesn't help you without an appropriate A/D converter.
Hi Chris, let's hope your computer allows you sound...
Why a soundblaster ? For measuring there are better soundcards, like the Esi@Juli, having balanced inputs and outputs. The rated 0.004% from the soundblaster will be real world above symasyms thd... 😀 Okay, already bought...
Like Holger said, input is max 96khz samplerate, giving max 48khz.
BTW, which OS do you use ?
Mike
Why a soundblaster ? For measuring there are better soundcards, like the Esi@Juli, having balanced inputs and outputs. The rated 0.004% from the soundblaster will be real world above symasyms thd... 😀 Okay, already bought...
Like Holger said, input is max 96khz samplerate, giving max 48khz.
BTW, which OS do you use ?
Mike
Hi ya all, especially Mike,
Didn’t have much time lately, but I’ve done this so far. This is the newest PCB version. Not ideal, but I think it’ll be a little bit better.
First of all, I’ve moved PSU ground (electrolytic capacitor’s ground) away from the input section, by placing a thick jumper beneath the PCB, connecting one + and one – of the 1000µF/50V electrolytic capacitors. Not quite elegant, but this line won’t interfere with the amp’s input anymore. By placing it beneath the PCB, it’ll also be a little bit further away from the 47k/220pF combination as well.
Electrolytic capacitors 1000µF/50V have been turned around for 90º to straight up supply leads feeding output trannies.
I’ve moved 47nF capacitor from the left of 4,7Ω/2W resistor, to its right, moving it away from the input section.
Last, but not least, I’ve turned one of the diff. input trannies, thus providing much better conditions for bonding these two together.
If anyone is interested that’s all for now. I’m in “obtaining components” phase right now, much as thinking of building four of these to convert my speakers into active ones. As time passes by, all the chances are I’ll stay with passive speakers.
Best regards to ya all,
Nick
Didn’t have much time lately, but I’ve done this so far. This is the newest PCB version. Not ideal, but I think it’ll be a little bit better.
First of all, I’ve moved PSU ground (electrolytic capacitor’s ground) away from the input section, by placing a thick jumper beneath the PCB, connecting one + and one – of the 1000µF/50V electrolytic capacitors. Not quite elegant, but this line won’t interfere with the amp’s input anymore. By placing it beneath the PCB, it’ll also be a little bit further away from the 47k/220pF combination as well.
Electrolytic capacitors 1000µF/50V have been turned around for 90º to straight up supply leads feeding output trannies.
I’ve moved 47nF capacitor from the left of 4,7Ω/2W resistor, to its right, moving it away from the input section.
Last, but not least, I’ve turned one of the diff. input trannies, thus providing much better conditions for bonding these two together.
If anyone is interested that’s all for now. I’m in “obtaining components” phase right now, much as thinking of building four of these to convert my speakers into active ones. As time passes by, all the chances are I’ll stay with passive speakers.
Best regards to ya all,
Nick
Attachments
Hi Nick, looks alright to me ! You might skip the right input elyt (and the 1M), the negative bias from the inputstage keeps the cap polarized unless you feed it with very low freqs.
Mike
Mike
PMA said:
Pavel,
Have you read the MJ Hawksford papers WRT cables effects on
sonics?
cheers
Terry
Hi Terry,
yes, I did, in case you mean the Essex Echo (transversal EM field influence).
Regards,
Pavel
yes, I did, in case you mean the Essex Echo (transversal EM field influence).
Regards,
Pavel
Hi Mike,
I use XP Home. It was good until now and usoft doesn't know how to fix it.
Hi HBarske,
A/D is supposed to be 192 KHz. The published specs seem to look good, we shall see. The older card was in trouble at 18 KHZ, so this is an improvement. I saw it on sale for $134 CDN, so I picked it up. Also hoping a mjor change would shock XP into working. No such luck.
I do plan to buy a DSO with FFT functions, so this is good enough for quick things on the bench.
Mike,
Don't worry, I'll measure THD with my normal stuff and look at the residuals. Might actually send the residuals to the sound card. I'm sure that will extend the usefullness.
-Chris
I use XP Home. It was good until now and usoft doesn't know how to fix it.
Hi HBarske,
A/D is supposed to be 192 KHz. The published specs seem to look good, we shall see. The older card was in trouble at 18 KHZ, so this is an improvement. I saw it on sale for $134 CDN, so I picked it up. Also hoping a mjor change would shock XP into working. No such luck.
I do plan to buy a DSO with FFT functions, so this is good enough for quick things on the bench.
Mike,
Don't worry, I'll measure THD with my normal stuff and look at the residuals. Might actually send the residuals to the sound card. I'm sure that will extend the usefullness.
-Chris
Terry,
That article is very very interesting, especially as a brains training. I am not sure that the reason MOH describes is the decisive one. It surely exists, but if you calculate it, it seems to be marginal (IMO). Also, it is very difficult to prove, regardless MOH's experiment shown.
To quantify and assess ... 🙂
That article is very very interesting, especially as a brains training. I am not sure that the reason MOH describes is the decisive one. It surely exists, but if you calculate it, it seems to be marginal (IMO). Also, it is very difficult to prove, regardless MOH's experiment shown.
To quantify and assess ... 🙂
Hi Chris, the specs say:
And this is rather usual for this type of soundcards. There are few who really do 192 A/D. I remember once having an EMU 1010 which was spec'd to do 192 on the A/D side, but it definitely did not. Noone of the music guys out there obviously was interested in that, so noone seemed to have noticed.
I second Mike's proposal of the ESI Juli@, that's a good one.
Mike,
found some differences between the the schematic/board you are showing on your website and the Eagle files you've posted - R16 and R19 so far.
Which one is the latest version?
found some differences between the the schematic/board you are showing on your website and the Eagle files you've posted - R16 and R19 so far.
Which one is the latest version?
Hi Holger, for standard symasym r16/19 are shorted out, i included them as option, needed if gain needs to be lowered and safety precaution for the case that even faster ouputdevices than Toshibas are used. On the assembled board you see them as wires.
Mike
Mike
Hi HBarske,
The spec I was actually looking at was:
When I should be looking at :
If I can get my sound working, I'll let you know how it does.
-Chris
Oops, that's not what I was interested in anyway, thanks for pointing that out.
The spec I was actually looking at was:
When I should be looking at :
As long as it doesn't brick wall around 22 KHz, I can live with it for quick bench tests. I would love a better card, but I'm on a fixed income and trying to save for a DSO.
If I can get my sound working, I'll let you know how it does.
-Chris