Am i correct ?
Hi, all
i just have build my SOZ`s and BoSoz`s. They are in beta state.that means, the case for the amps is not finished yet.
This is the chance for me to upgrade to XSoz and XBoSoz.
I have seen and downloaded several schematics and have one question:
After implementing the new schematic -parts to Soz, has the old resistor R7 (1ohm) be bridged or does it stay?
After implementing the new schematic to BoSoz, has the old Resistor R15 (124 ohm to be bridged or does it stay?
If the sound of Soz /Bosoz will be topped through X it would be fantastic...
Thank you all,
regards,
Ralf
Hi, all
i just have build my SOZ`s and BoSoz`s. They are in beta state.that means, the case for the amps is not finished yet.
This is the chance for me to upgrade to XSoz and XBoSoz.
I have seen and downloaded several schematics and have one question:
After implementing the new schematic -parts to Soz, has the old resistor R7 (1ohm) be bridged or does it stay?
After implementing the new schematic to BoSoz, has the old Resistor R15 (124 ohm to be bridged or does it stay?
If the sound of Soz /Bosoz will be topped through X it would be fantastic...
Thank you all,
regards,
Ralf
Ralf
There have ben many suggestions on how to apply X to the original BSOZ and SOZ.
In my version, posted at page 17, R15 in the BSOZ is replaced with wire in the XBSOZ and R7 in SOZ is also replaced with wire in the XSOZ.
I have described the sonical change from the original circiuts to the X.
I am very pleased with the result, it certainly is an improvement.
But if You deside to make my version, be aware of the very low inputimpedance at the XSOZ, it is only 120 Ohm singleended and 240 balanced. Not many other preamps will be able to drive this low impedance, not even the original BSOZ.
There have ben talking much about wether the BSOZ or XBSOZ is good at converting a singleended input to a balanced output or not.
I do have a feeling, that the XBSOZ woud sound better with a current source at the tail, also becauce the X-feedback will suffer more or less from mismatch in the diffrential amplification. Therefore I am doing some experiments on this toppic.
I hope I will have some results to post to morrow.
There have ben many suggestions on how to apply X to the original BSOZ and SOZ.
In my version, posted at page 17, R15 in the BSOZ is replaced with wire in the XBSOZ and R7 in SOZ is also replaced with wire in the XSOZ.
I have described the sonical change from the original circiuts to the X.
I am very pleased with the result, it certainly is an improvement.
But if You deside to make my version, be aware of the very low inputimpedance at the XSOZ, it is only 120 Ohm singleended and 240 balanced. Not many other preamps will be able to drive this low impedance, not even the original BSOZ.
There have ben talking much about wether the BSOZ or XBSOZ is good at converting a singleended input to a balanced output or not.
I do have a feeling, that the XBSOZ woud sound better with a current source at the tail, also becauce the X-feedback will suffer more or less from mismatch in the diffrential amplification. Therefore I am doing some experiments on this toppic.
I hope I will have some results to post to morrow.
Henrik
I run the program with the connection of BOSOZ (unbalanced-balanced) and XSOZV2.
Results are:
I will try to attach the Zip file tomorrow, for your opinion.
I run the program with the connection of BOSOZ (unbalanced-balanced) and XSOZV2.
Results are:
- Lower critical f = 9 Hz (-3dB)
- Upper critical f = 90 kHZ (-3dB)
I will try to attach the Zip file tomorrow, for your opinion.
jh6you
I got it a little different than you, but the most important difference in measurements is when You substitute the irfp150 with irf130. The Irf130 has only half the inputcapaciance of the irfp150. I presume that´s the reason for the lower cut off for the irfp150.
The red curve is irfp150 and the green is irf130.
I would go for -1db at 20kHz / -3db at 100kHz.
I got it a little different than you, but the most important difference in measurements is when You substitute the irfp150 with irf130. The Irf130 has only half the inputcapaciance of the irfp150. I presume that´s the reason for the lower cut off for the irfp150.
The red curve is irfp150 and the green is irf130.
I would go for -1db at 20kHz / -3db at 100kHz.
Attachments
Henrik
Thanks Henrik,
two questions,
MA1091 - are they zener diodes with 9.1 V ?
Do you think Irfp240 are the right ones for the x soz?
Thanks,
Ralf
Thanks Henrik,
two questions,
MA1091 - are they zener diodes with 9.1 V ?
Do you think Irfp240 are the right ones for the x soz?
Thanks,
Ralf
jh6you
I didn´t see your post, it came while i was writing.
-3db at 9Hz is a little too hig to me, I would go for -3db at 1-5Hz.
-3 db at 90 kHz is almost ok I think.
It also depends on the shape of the roll off, so I think the best is to measure it at 20Hz and 20kHz and then make it -0.1db.
This is my expirience so far.
I didn´t see your post, it came while i was writing.
-3db at 9Hz is a little too hig to me, I would go for -3db at 1-5Hz.
-3 db at 90 kHz is almost ok I think.
It also depends on the shape of the roll off, so I think the best is to measure it at 20Hz and 20kHz and then make it -0.1db.
This is my expirience so far.
Henrik
You need to adjust R4 (10k) to get the quiscent voltage of +18,
i.e. down to about 7k. Then, you will get about 80 kHz instead of
71.34 kHz.
I agree with you. The upper critical frequency point will vary
according to the input Miller capacitance. Therefore, we need to
use MOSFET having low C(gs) and C(gd).
I will try to replace IRFP150 with better one.
You need to adjust R4 (10k) to get the quiscent voltage of +18,
i.e. down to about 7k. Then, you will get about 80 kHz instead of
71.34 kHz.
I agree with you. The upper critical frequency point will vary
according to the input Miller capacitance. Therefore, we need to
use MOSFET having low C(gs) and C(gd).
I will try to replace IRFP150 with better one.
Ralf
Yes, MA1091 is zevers at 9.1 V.
I am using Irfp240 for my SOZ, but I will replace them with IRFP140. They shoud sound better, even when they have a higer inputcapacitance. But if You have the IRFP240, use them, I don´t think it matter that much, but I haven´t heard the difference my self.
Yes, MA1091 is zevers at 9.1 V.
I am using Irfp240 for my SOZ, but I will replace them with IRFP140. They shoud sound better, even when they have a higer inputcapacitance. But if You have the IRFP240, use them, I don´t think it matter that much, but I haven´t heard the difference my self.
---------------------------------------------------------------------------------
It also depends on the shape of the roll off, so I think the best is to measure it at 20Hz and 20kHz and then make it -0.1db.
---------------------------------------------------------------------------------
There are not only bandwidths, but also other aspects
I have to consider.
Anyhow, no problem. I will re-try.
It also depends on the shape of the roll off, so I think the best is to measure it at 20Hz and 20kHz and then make it -0.1db.
---------------------------------------------------------------------------------
There are not only bandwidths, but also other aspects
I have to consider.
Anyhow, no problem. I will re-try.
Henrik
I suspect the frequency response curve (red color) made with IRF150.
I checked C(gs) and C(gd) of IRF150 used in your spice model and
found the values of 9027pF and 1679pF respectively. According to
my data, however, IRFP150 has typical 1650pF and 650pF. Since these
two values are essential to calculate the input Miller capacitance,
using the correct values are demanded.
In principle, amp designers might set up their target to achieve
audio frequency between 20Hz and 20kHz and corresponding critical
frequencies of 2Hz and 200kHz. I however doubt if these are the first
condition for the good amp sound.
Books indicate that the upper critical frequency is very much up to
the input Miller capacitance and the input resistance. I again changed
R5 to 7.5K and R4 to 5.5k (adjustment for the quiescent voltage) and
did re-run the program with IRF130. Results are:
the results somewhat vary depending on the input attenuator (volume) setting.
I hardly expect any problem if the BW is between 2Hz and 100kHZ.
Your preference of -0.1dB at 20kHz could be a meaninful indication...?
That is just the output signal voltage level of about 98.8% of its
midrange value.
By the way, how is it going your feasibility study of BSOZ having
constant current source tails? I am very interested in.
I suspect the frequency response curve (red color) made with IRF150.
I checked C(gs) and C(gd) of IRF150 used in your spice model and
found the values of 9027pF and 1679pF respectively. According to
my data, however, IRFP150 has typical 1650pF and 650pF. Since these
two values are essential to calculate the input Miller capacitance,
using the correct values are demanded.
In principle, amp designers might set up their target to achieve
audio frequency between 20Hz and 20kHz and corresponding critical
frequencies of 2Hz and 200kHz. I however doubt if these are the first
condition for the good amp sound.
Books indicate that the upper critical frequency is very much up to
the input Miller capacitance and the input resistance. I again changed
R5 to 7.5K and R4 to 5.5k (adjustment for the quiescent voltage) and
did re-run the program with IRF130. Results are:
- Lower Fc = 2 (-3dB)
- Upper Fc = 100 (-3dB)
the results somewhat vary depending on the input attenuator (volume) setting.
I hardly expect any problem if the BW is between 2Hz and 100kHZ.
Your preference of -0.1dB at 20kHz could be a meaninful indication...?
That is just the output signal voltage level of about 98.8% of its
midrange value.
By the way, how is it going your feasibility study of BSOZ having
constant current source tails? I am very interested in.
Let´s get some more fire!
jh6you
However, the bandwidth is essential, if it is too narrow You can have all other virtues in its place and it still sounds crappy.
In my first tests of the XSOZ I realised that it was down -1db @ 20kHz.
When I lowered the input impedance in XSOZ from 1k to 120 Ohm and output impedance in the XBSOZ from 1.4k to 10 Ohm, the subjektive quality of the sound increased the most, all the virtues of the X was relieved, the relaxed and easy sound was better than ever.
IRF´s own data:
Irfp150 InputC is 2800pF
Irfp140 InputC is 1700pF
Irf130 InputC is 650
So if IRFP150 Spicemodel is set to 9027 something is wrong.
May be we shoud try IRF´s own spicemodels.
We can hear 20 - 20kHz, not 1Hz or 100kHz, so my common sence tells me, that 20Hz and 20kHz is the band to focus on. And -1db in this area is audible to me, but I am not shure if I can hear -0,1db, I don´t think so. So if I sets the bandwidth to 20Hz-20kHz @-0.1db I feel safe.
I have got the flue, but I still hope I will be able to do some tests on the tail-CCS in XBSOZ.
jh6you
However, the bandwidth is essential, if it is too narrow You can have all other virtues in its place and it still sounds crappy.
In my first tests of the XSOZ I realised that it was down -1db @ 20kHz.
When I lowered the input impedance in XSOZ from 1k to 120 Ohm and output impedance in the XBSOZ from 1.4k to 10 Ohm, the subjektive quality of the sound increased the most, all the virtues of the X was relieved, the relaxed and easy sound was better than ever.
IRF´s own data:
Irfp150 InputC is 2800pF
Irfp140 InputC is 1700pF
Irf130 InputC is 650
So if IRFP150 Spicemodel is set to 9027 something is wrong.
May be we shoud try IRF´s own spicemodels.
We can hear 20 - 20kHz, not 1Hz or 100kHz, so my common sence tells me, that 20Hz and 20kHz is the band to focus on. And -1db in this area is audible to me, but I am not shure if I can hear -0,1db, I don´t think so. So if I sets the bandwidth to 20Hz-20kHz @-0.1db I feel safe.
I have got the flue, but I still hope I will be able to do some tests on the tail-CCS in XBSOZ.