tlf9999 said:
Hi,Mr.Graham & Mr.tlf9999:
thank you at fist for reply...
I have already try using headphone output to drive my IRF510's JLH mos amp,it must turn to MAX of the volume position,and I didn't heard difference,so I suppose that isn't my CD's problem,after know yours can hear bass well,I think this my loudspeaker's problem,my speaker just only 3" full range speaker units,perhaps it can't process well bass than yours...but they sounds wonderful, I like them very much!so more strong bass my speaker needed,and more low frequency output from my designed AMP...that is why I think the JLH1969 can't process bass well and do modification with it...
I still carry on my idea!because it has more width frequency response...
have fun,my friends!
WINCO
Hi Tim,
Regarding source impedance;-
I am not going to attempt to give any specific rules in this regard, other than repeat JLH's prior recommendation.
It is thus most likely that anyone driving a JLH amplifier directly from a potentiometer or a source having output resistance greater than 1k could enjoy better reproduction definition than they realised was possible with such a simple circuit.
I must leave it up to each user to check out their own source arrangements, and maybe this is one reason why some constructors are entirely satisfied whilst others cannot understand how they could be !
Hi Darkhorse,
I do not know of any 3" driver capable of producing full 'bass' from a flat system.
Cheers ........ Graham.
Regarding source impedance;-
I am not going to attempt to give any specific rules in this regard, other than repeat JLH's prior recommendation.
It is thus most likely that anyone driving a JLH amplifier directly from a potentiometer or a source having output resistance greater than 1k could enjoy better reproduction definition than they realised was possible with such a simple circuit.
I must leave it up to each user to check out their own source arrangements, and maybe this is one reason why some constructors are entirely satisfied whilst others cannot understand how they could be !
Hi Darkhorse,
I do not know of any 3" driver capable of producing full 'bass' from a flat system.
Cheers ........ Graham.
For all you JLH fans out there ...
The one-and-only has published a draft of an excelent article on the JLH topology:
www.passlabs.com/np
grzzz,
Thijs
The one-and-only has published a draft of an excelent article on the JLH topology:
www.passlabs.com/np
grzzz,
Thijs
tschrama said:
so hopefully there will be no doubt that the mosfet version of the JLH is indeed JLH,
.Here is my implementatio of the PLH.
a few observations:
a) the amp porformed very well and tracked the JLH1969 well.
b) the gain is quite sensitive to the phase splitter used. I got 10x gain with irf510/610, but only 4x with other irf540/p140 and mje15032. Not sure if it is a model problem or there is something special about the irf510/610.
c) the use of a current source as the load helped improve the gain. However, disortion goes through the roof if the amp is not biased in class A. the bootsrape network offers comparable performance but allows the amp to be biased in class AB. To me, that is a superior arrangement.
Attachments
played around with the input stage a little.
With IRF510, the gain starts to dip at 10khz, and phase shift is quite excessive: 70 degrees at 100khz. However, distortion is almost non-existant.
With 2n5551, the gain stayed flat all the way to about 100khz. and phase shift is about 30 degrees at 100khz. However distortion is just shy of .5%.
I am a little torn between using a small signal mosfet and a fast BJT. I will try to listen to both this weekend and see how they sound.
With IRF510, the gain starts to dip at 10khz, and phase shift is quite excessive: 70 degrees at 100khz. However, distortion is almost non-existant.
With 2n5551, the gain stayed flat all the way to about 100khz. and phase shift is about 30 degrees at 100khz. However distortion is just shy of .5%.
I am a little torn between using a small signal mosfet and a fast BJT. I will try to listen to both this weekend and see how they sound.
tlf9999 said:
For me this is a bit like saying what is better oranges or apples
If I had sensitive enough speakers and / or I was driving the bass with another amp, I'm guessing ( my own amp having similarities to X-pros and having just built Nelson's one in spice ) that I MAY prefer Nelson's, especially on some cd's that seem to emphasise detail. On other recordings, that already sound smooth on my system, it may be I would prefer mine or X-pros or something inbetween these and the PLH
I do not think that Nelson's amp would excell with 87db/W/M speakers with a 4 ohm tweeter and 8 ohm mid/bass unit with impedance dropping to 1.5 ohms in the cross-over region for instance....on the other hand with 102dB / W / m speakers in some kind of horn, Nelson's amp I'm sure would up there with the best ......but there will still be many who may prefer a SET or Susan Parker zeus type amp or firstwatt current drive or valve push pull.....
Not to even mention power supply design
As well as absolute design quality there is a large amount of horses for courses / amps for speakers AND personal preference that makes black & white comparisons, like the question is apparently looking for, almost completely meaningless.
Having said all that, being a Luddite at heart, I really like the back to basics simple, clever, listening based, designs in which Nelson seems to excel. All of which means I am going to build one to hear for myself which ultimately is the only way for each of us to find out which is "best"...