Hello
Excuse me my wrong English, Is the first time that I Have wrote in this forum and, of course, the first time that I write in English language forum.
I have finished a LA-2A replica with amazing and warm sound. They have some of the following characteristics:
Cell:
LDR : NSL5910 (two for audio path and one for VU-meter)
Panel, Farnell, colour aqua.
Input transformer: SOWTER 4383 (1:4)
Output transformer: Home made audio transformer (2,5:1)
R7 = 1K (more resistance reveal “negative compression” in Limiter position.
6AQ5 is substitute with 6V6.
Is there another change without importance now.
Now I am proceeding at the specific and precise audio measurements.
I measure the output THD, first without compression for different output levels, (with a low distortion audio generator and ARTA computer Software).
Output THD (%)
+10dB 0,12%
+15% 0,23%
+20dB 0,42%
23,2dB 1%
24dB Clip
I thing are good characteristics, but the problem is when the compression is present.
THE PROBLEM
When the compression is present, the THD is rising, until very high values, more than 3 or 4%...... I have seeing the THD is rising until the compression arrive at -3dB (of compression), with more compression the THD is come down until 1% more or less. I DON’T UNDERSTANT ANYTHING, because the LDR action is pure resistive….
Any body have an idea or can help me?
Thanks
Miquel
Excuse me my wrong English, Is the first time that I Have wrote in this forum and, of course, the first time that I write in English language forum.
I have finished a LA-2A replica with amazing and warm sound. They have some of the following characteristics:
Cell:
LDR : NSL5910 (two for audio path and one for VU-meter)
Panel, Farnell, colour aqua.
Input transformer: SOWTER 4383 (1:4)
Output transformer: Home made audio transformer (2,5:1)
R7 = 1K (more resistance reveal “negative compression” in Limiter position.
6AQ5 is substitute with 6V6.
Is there another change without importance now.
Now I am proceeding at the specific and precise audio measurements.
I measure the output THD, first without compression for different output levels, (with a low distortion audio generator and ARTA computer Software).
Output THD (%)
+10dB 0,12%
+15% 0,23%
+20dB 0,42%
23,2dB 1%
24dB Clip
I thing are good characteristics, but the problem is when the compression is present.
THE PROBLEM
When the compression is present, the THD is rising, until very high values, more than 3 or 4%...... I have seeing the THD is rising until the compression arrive at -3dB (of compression), with more compression the THD is come down until 1% more or less. I DON’T UNDERSTANT ANYTHING, because the LDR action is pure resistive….
Any body have an idea or can help me?
Thanks
Miquel