They are 10W measurement grade 4-leaded film resistors specified at 10nH stray inductance.
Patrick
Patrick
Whew............! I'd never have guessed that.
Wondered why it had unconnected leads............
Who makes them ?
Thanks.
Ashok.
Wondered why it had unconnected leads............
Who makes them ?
Thanks.
Ashok.
http://www.isabellenhuette.de/pdf/passiv/pbv.pdf
Two of the leads are for carrying current, twofor sensing the voltage drop across the resistor. This is a common method for measuring high current across low value resistors.
Patrick
Two of the leads are for carrying current, twofor sensing the voltage drop across the resistor. This is a common method for measuring high current across low value resistors.
Patrick
Hi Patrick,
I figured out the purpose of the leads after you said it was a measurement grade resistor.
However I've never seen this one before.
I guess this must be expensive. Are you using it to monitor current flow on a meter or does it go to some circuitry to control bias current automatically ?
Ashok.
I figured out the purpose of the leads after you said it was a measurement grade resistor.
However I've never seen this one before.
I guess this must be expensive. Are you using it to monitor current flow on a meter or does it go to some circuitry to control bias current automatically ?
Ashok.
> I guess this must be expensive.
About 3 Euros each.
> Are you using it to monitor current flow on a meter or does it go to some circuitry to control bias current automatically ?
No, just what I have around.
Patrick
About 3 Euros each.
> Are you using it to monitor current flow on a meter or does it go to some circuitry to control bias current automatically ?
No, just what I have around.
Patrick
Input Capacitor /Mundorf Silver-in-Oil and Mundorf Silver-in-Gold
Hi JLH diyer,
Is there anyone using Mundorf Silver-in-Oil and Mundorf Silver-in-Gold and Jensen Copper-in-Oil for the input capacitor?
What is the quality sound of High End, Mid-Range & Bass?
Which one is better?
Best regards
Dominic Ko
Hi JLH diyer,
Is there anyone using Mundorf Silver-in-Oil and Mundorf Silver-in-Gold and Jensen Copper-in-Oil for the input capacitor?
What is the quality sound of High End, Mid-Range & Bass?
Which one is better?
Best regards
Dominic Ko
Jensen
Hi Dominic,
no experience with Jensen Copper in oil, but I have Jensen paper-in-oil in my second project.
I have no comparisons made with other caps, but compared to my first project where i just used a 'no-spec' capacitor for the input the second amp has more bass and overall sound quality is excellent (i think).
Jos
Hi Dominic,
no experience with Jensen Copper in oil, but I have Jensen paper-in-oil in my second project.
I have no comparisons made with other caps, but compared to my first project where i just used a 'no-spec' capacitor for the input the second amp has more bass and overall sound quality is excellent (i think).
Jos
Regulated vs Unregulated PS in JLH
Hello to all,
Since two months I have a set of extremely sensitive loudspeakers hooked on to my JLH (as I would call 109dB / W extremely sensitive).
They revealed an audible hum in one of my j-amp 2003 which needs to be cured, so I dug out my j-amp 2000.
On both amps the loudspeakers reveal a tiny hiss which most likely is related to the regulated power supply. The hiss is however audible 'less present' on the j-amp 2003.
I've hooked up an scoop to the humming j-amp 2003 and found, besides a 50hz factor a tiny bump in the output with the input open. I forgot to take measurements.
So here's a point for those disliking the ic-regulated power supplies, so a comparison with a JLH without regulated PSU is most wanted. Anyone interested??
I will gather some more data as I start curing the j-amp 2003, but it will be a month or two before I've time for that.
Hello to all,
Since two months I have a set of extremely sensitive loudspeakers hooked on to my JLH (as I would call 109dB / W extremely sensitive).
They revealed an audible hum in one of my j-amp 2003 which needs to be cured, so I dug out my j-amp 2000.
On both amps the loudspeakers reveal a tiny hiss which most likely is related to the regulated power supply. The hiss is however audible 'less present' on the j-amp 2003.
I've hooked up an scoop to the humming j-amp 2003 and found, besides a 50hz factor a tiny bump in the output with the input open. I forgot to take measurements.
So here's a point for those disliking the ic-regulated power supplies, so a comparison with a JLH without regulated PSU is most wanted. Anyone interested??
I will gather some more data as I start curing the j-amp 2003, but it will be a month or two before I've time for that.
I run my JLH's on unregulated supplies and have no audible hum or hiss unless I put my ear next to the speakers which are composed of 2 94db/w 12 woofers,klipsch k400 mid horns rated around 104db/w and a panasonic 5x9 horn tweeter at 102db/w per speaker. The only time I find a problem with noise is when I turn on the ac and it draws a large initial current which drops the supply a few volts then back. Attached the scematic that i use which is a very mildly modified 69 version.
Attachments
I have two pairs of 2SC2625, they where pulled off from a AT power supply. Would they able to work in a 69's JLH, just for prototyping?
A have some MJL4281 too, but I'm afraid of oscilations. As driver I'm thinking to use the MJE15034.
A have some MJL4281 too, but I'm afraid of oscilations. As driver I'm thinking to use the MJE15034.
jerluwoo said:
What voltage are the rails, what Iq and how much capacitance?
I'm hoping to get away with 60mF and 3A Iq, which I estimate will give about 500mV ripple. I've never seen a figure for PSRR for the JLH, any ideas?
thanks
My supply is +/- 22 volts with 44mF capacitance. Idle current is 1.7 amps ( all I could get before voltage sag).
I do not think the JLH has any problems with oscilation because of its topology (it requires no compensation caps).
I do not think the JLH has any problems with oscilation because of its topology (it requires no compensation caps).
Hi jerluwoo,
I have completed the amp with the following config:-
1) 15V x2 Dual Supply with 18V x 2 output voltage.
2) Filter is CLC with 100000uf - 2.5mH - 14700uf
3) Updated JLH version
4) Matched MJ15003 Transistor
5) IQ current is 1.4 and DC offset is < 40mV after warm up.
The power supply is very stable without any problems when starting up.
There is no hum due to JLH amp. But this amp is very very sensitive.
10Hz to 22KHz, there is good freq respone. (10uf Coupling). If there is some problems about the source, you will hear what's defeat.
If there is no problems, your amp will sound really good, clean and warm.
Best regard
Dominic
I have completed the amp with the following config:-
1) 15V x2 Dual Supply with 18V x 2 output voltage.
2) Filter is CLC with 100000uf - 2.5mH - 14700uf
3) Updated JLH version
4) Matched MJ15003 Transistor
5) IQ current is 1.4 and DC offset is < 40mV after warm up.
The power supply is very stable without any problems when starting up.
There is no hum due to JLH amp. But this amp is very very sensitive.
10Hz to 22KHz, there is good freq respone. (10uf Coupling). If there is some problems about the source, you will hear what's defeat.
If there is no problems, your amp will sound really good, clean and warm.
Best regard
Dominic
J-amp 2003 rail voltages
On J-amp 2003 settings are
Vrail = 29V; Iq is now 1A and Cres = 51.700 uF (47.000 + 4.700).
and a quad of matched MJ15003's.
On J-amp 2001 settings are
Vrail = 22 V; Iq is now 700mA Cres = 22.000 uf
and a pair of matched (ST) 2N3055
this one has a tiny oscillation on power-on, but fades away on my hearing, but my son of twelf is not quite sure it's gone.
No scope measurements taken (yet)
bremen nacht said:
On J-amp 2003 settings are
Vrail = 29V; Iq is now 1A and Cres = 51.700 uF (47.000 + 4.700).
and a quad of matched MJ15003's.
On J-amp 2001 settings are
Vrail = 22 V; Iq is now 700mA Cres = 22.000 uf
and a pair of matched (ST) 2N3055
this one has a tiny oscillation on power-on, but fades away on my hearing, but my son of twelf is not quite sure it's gone.
No scope measurements taken (yet)
Hi,Nelson:
I was wrong with the Iq of Ouput stage,Because IRF510's GM about 1S or a littel more above 1S,so I should adjusted it to about 0.5A(Iq),it can proccess more output power and decrease distortion.
I build the last version last night,when I finish the work, it was too late(midnight),even today is sunday,but I have my overtime job...
only can wait for tonight,I can carry on my project of this small amp.
the circuit I build:
I was wrong with the Iq of Ouput stage,Because IRF510's GM about 1S or a littel more above 1S,so I should adjusted it to about 0.5A(Iq),it can proccess more output power and decrease distortion.
I build the last version last night,when I finish the work, it was too late(midnight),even today is sunday,but I have my overtime job...
only can wait for tonight,I can carry on my project of this small amp.
the circuit I build:
