JLH VR3 offset variation adjustment
Can anybody help please?
I have just re-built my JLH circuit from http://www.gmweb.btinternet.co.uk/jlhupdate.htm figure 2 and I have noticed that VR3 has almost no effect on whether the offset rises, or falls during warm-up. After checking the circuit and replacing the ccs transistors I am starting to suspect that the 10K preset I have used for VR3 does not offer enough range of adjustment to overcome other variables. The dc offset variation between hot and cold is around 60mV, so it is not a problem. However I would be very interested to hear from anyone else who has had a similar expereince with VR3. Or if VR3 has been effective in reducing the offset variation between hot and cold, I would very much like to know how effective VR3 was.
Many thanks in advance for any answers.
Tim.
Can anybody help please?
I have just re-built my JLH circuit from http://www.gmweb.btinternet.co.uk/jlhupdate.htm figure 2 and I have noticed that VR3 has almost no effect on whether the offset rises, or falls during warm-up. After checking the circuit and replacing the ccs transistors I am starting to suspect that the 10K preset I have used for VR3 does not offer enough range of adjustment to overcome other variables. The dc offset variation between hot and cold is around 60mV, so it is not a problem. However I would be very interested to hear from anyone else who has had a similar expereince with VR3. Or if VR3 has been effective in reducing the offset variation between hot and cold, I would very much like to know how effective VR3 was.
Many thanks in advance for any answers.
Tim.
Shouldn't it be a 20K instead of 10K?
Hi Tim,
Why not try a 20K preset VR3 as suggested in the Geoff's site first ?
Ralf,
In my case Iq set at 4A sound the best. As to the smooth sound finding, C1 is one of the key components that can affect the voice of the amp a lot. Some say paper in oil cap here sound good..so try different types here to suit your taste..
Regards,
Chris
Hi Tim,
Why not try a 20K preset VR3 as suggested in the Geoff's site first ?
Ralf,
In my case Iq set at 4A sound the best. As to the smooth sound finding, C1 is one of the key components that can affect the voice of the amp a lot. Some say paper in oil cap here sound good..so try different types here to suit your taste..
Regards,
Chris
tricky thing
Hi,
it seems to be a tricky thing with the dc offset.
as you know i builded the high power version.
after first problems getting the circuit offseted it worked.
i think this circuit is that good to invest in best high grade parts and make all the modifications as Tim told.
my next modification is to link C4.
after i did that i had a new dc offset problem.
which values of pots and resistors shall i use?
CHRIS:
did you use silver-paper-in oil or aluminium or kopper type.
I will spend much money to high grade parts, but a jensen or AN silver type: too expensive!
i read in an article (tnt audio) that AURICAP should bet better than jensen alu-paper-in-oil.
i competed my jensen alu paper in oil with a siemens MKV type: hardly a difference ,but big diffrence to Mundorf tin foil (this sounds less good).
greets,
Ralf
Hi,
it seems to be a tricky thing with the dc offset.
as you know i builded the high power version.
after first problems getting the circuit offseted it worked.
i think this circuit is that good to invest in best high grade parts and make all the modifications as Tim told.
my next modification is to link C4.
after i did that i had a new dc offset problem.
which values of pots and resistors shall i use?
CHRIS:
did you use silver-paper-in oil or aluminium or kopper type.
I will spend much money to high grade parts, but a jensen or AN silver type: too expensive!
i read in an article (tnt audio) that AURICAP should bet better than jensen alu-paper-in-oil.
i competed my jensen alu paper in oil with a siemens MKV type: hardly a difference ,but big diffrence to Mundorf tin foil (this sounds less good).
greets,
Ralf
oil
Ralf,
The part that I used for C1 is the same one in the picture in Geoff's site. The part number is 365-7479 from RS component uk.
It is not expensive at all and I like its sound. I used the 2.2uf one. I would like to try paper in oil too but worry that it may sound too smooth.
**************************************
Designed for high performance audio systems
Low ESR and low self inductance
High stability with respect to both temperature and frequency
Ideal for use in loudspeaker crossover networks and valve amplifiers where pure sound is at a premium
technical specification
Capacitance tolerance ±5%
Working voltage 630V d.c.
Temperature range -40 to +85°C
Insulation resistance >1,000s @ 20°C
Dissipation factor <0·001 @ 1kHz and 20°C
Terminations 70mm long, 1/1·0 copper with
PVC insulation
Case Flame retardant
polypropylene, epoxy resin
filled
Markings Capacitance, tolerance,
working voltage, outer foil
end
Dimensions
Capacitance Length Dia.
mF
1·0 47 22
2·2 47 22
3·3 55 30
4·7 55 30
6·8 70 30
10 70 35
**********************************************
Regards,
Chris
Ralf,
The part that I used for C1 is the same one in the picture in Geoff's site. The part number is 365-7479 from RS component uk.
It is not expensive at all and I like its sound. I used the 2.2uf one. I would like to try paper in oil too but worry that it may sound too smooth.
**************************************
Designed for high performance audio systems
Low ESR and low self inductance
High stability with respect to both temperature and frequency
Ideal for use in loudspeaker crossover networks and valve amplifiers where pure sound is at a premium
technical specification
Capacitance tolerance ±5%
Working voltage 630V d.c.
Temperature range -40 to +85°C
Insulation resistance >1,000s @ 20°C
Dissipation factor <0·001 @ 1kHz and 20°C
Terminations 70mm long, 1/1·0 copper with
PVC insulation
Case Flame retardant
polypropylene, epoxy resin
filled
Markings Capacitance, tolerance,
working voltage, outer foil
end
Dimensions
Capacitance Length Dia.
mF
1·0 47 22
2·2 47 22
3·3 55 30
4·7 55 30
6·8 70 30
10 70 35
**********************************************
Regards,
Chris
JLH input capacitor
C1.....The A.N. p-in-o caps are smooth, but also very detailed. If you desire a 'big' sound with 'full' bass and substantial textural detail I suggest you try these if you can get them. Ansar 'supersound' sound quite nice, and I prefer these to Hovland 'musicaps' which sounded rather brittle, but the A.N. p-in-oil caps are better than either, in my opinion. However, I currently use a 0.33uF polystyrene capacitor which conveys more detail than any other capacitor I have tried so far, but it sounds a little 'squeaky' in the treble. The cure for this is a small 47nF p-in-oil connected across it. This combination offers even more detail than the 0.47uF A.N. p-in-oil alone yet with smoothness too.
My P-in-O preference is for A.N. copper foil which, due to its more natural sound I find preferable to the Jensen tin/aluminium foil. I haven't tried silver foil, though I would very much like to.
Tim.
C1.....The A.N. p-in-o caps are smooth, but also very detailed. If you desire a 'big' sound with 'full' bass and substantial textural detail I suggest you try these if you can get them. Ansar 'supersound' sound quite nice, and I prefer these to Hovland 'musicaps' which sounded rather brittle, but the A.N. p-in-oil caps are better than either, in my opinion. However, I currently use a 0.33uF polystyrene capacitor which conveys more detail than any other capacitor I have tried so far, but it sounds a little 'squeaky' in the treble. The cure for this is a small 47nF p-in-oil connected across it. This combination offers even more detail than the 0.47uF A.N. p-in-oil alone yet with smoothness too.
My P-in-O preference is for A.N. copper foil which, due to its more natural sound I find preferable to the Jensen tin/aluminium foil. I haven't tried silver foil, though I would very much like to.
Tim.
dc offset o.k
Hi,
my next improvement was to link C4.
it took a while to get dc offset near to zero.
the experiences, Tim made are reproduceable to my setup.
the sound differences are again better without C4.
one of the remarable points are realy pianos.
there is a song of rene aubri with brutal high piano attack.
None of my previous-build amps can play these attacs so that one can detect them as clean piano notes.
i will change the resisrors to Caddock types and will increase the
iq to 4 amps.
Since money is no object: do you think it makes sense to put more capacitance in the capacitor multiplier?
thanks to Geoff, Tim and the others
Greets,
Ralf
Hi,
my next improvement was to link C4.
it took a while to get dc offset near to zero.
the experiences, Tim made are reproduceable to my setup.
the sound differences are again better without C4.
one of the remarable points are realy pianos.
there is a song of rene aubri with brutal high piano attack.
None of my previous-build amps can play these attacs so that one can detect them as clean piano notes.
i will change the resisrors to Caddock types and will increase the
iq to 4 amps.
Since money is no object: do you think it makes sense to put more capacitance in the capacitor multiplier?
thanks to Geoff, Tim and the others
Greets,
Ralf
Capacitance multiplier
Hi all,
I make a separate connection for the output stages to the first capacitor banks, so only the input stage have capacitance mult. I find it sound better. (But now I have a loud thud on turn on though.)
Now I'm thinking of using separate cap mult for the output and input stages. Any suggestion ?
Cheers
Hi all,
I make a separate connection for the output stages to the first capacitor banks, so only the input stage have capacitance mult. I find it sound better. (But now I have a loud thud on turn on though.)
Now I'm thinking of using separate cap mult for the output and input stages. Any suggestion ?
Cheers
testing
yes i`ve tested against SOZ/Bosoz and the newer XSoz/XBosoz of pass design, further against hiraga monster and commercial triode tube monos (leak),
jlh outperforms all of them in all sound aspects like natural colors, attack and microresolution.
next time i will build pass newest flagship aleph x. i am curious about the comarison to jlh...
Greets, Ralf
yes i`ve tested against SOZ/Bosoz and the newer XSoz/XBosoz of pass design, further against hiraga monster and commercial triode tube monos (leak),
jlh outperforms all of them in all sound aspects like natural colors, attack and microresolution.
next time i will build pass newest flagship aleph x. i am curious about the comarison to jlh...
Greets, Ralf
Hi Chris,
I'm building the 1996 version with the modification as in Geoff Moss' page. I used the PSU from the original article, with addition in the capacitor value. Let me try to do some ASCII drawing, see whether it will make sense
.
Amp :
Input--2N1711 & MJE371-- MJ15003
PSU
Trans--14700uF--voltage regulator--9400uF
So :
the 2N1711 & MJE 371 are connected to the 9400uF caps
the 15003 are connected after the 14700uF caps
I used a 0.33 Ohm resistor conneted to the MJE 371 for initial bias current adjustment, after that I shorted the 0.33 resistor.
Hope this make sense
I'm building the 1996 version with the modification as in Geoff Moss' page. I used the PSU from the original article, with addition in the capacitor value. Let me try to do some ASCII drawing, see whether it will make sense
.Amp :
Input--2N1711 & MJE371-- MJ15003
PSU
Trans--14700uF--voltage regulator--9400uF
So :
the 2N1711 & MJE 371 are connected to the 9400uF caps
the 15003 are connected after the 14700uF caps
I used a 0.33 Ohm resistor conneted to the MJE 371 for initial bias current adjustment, after that I shorted the 0.33 resistor.
Hope this make sense
V
Ralf,
I'm starting to build the high-power version of the JLH, I can tell within half a year or so what the difference between my current JLH (with basic good but not audio-grade stuff) and the new which will include the use of P-I-O for C1, HolCo resistors for anthing but current-sources and Panasonic FC for the other capacitors in the amp.
Ralf,
I'm starting to build the high-power version of the JLH, I can tell within half a year or so what the difference between my current JLH (with basic good but not audio-grade stuff) and the new which will include the use of P-I-O for C1, HolCo resistors for anthing but current-sources and Panasonic FC for the other capacitors in the amp.
Separate connection for output stages
Hi dutch,
I'm still changing the connection point & caps values. If I connect both stages after the regulator -> no thump,but if I connect both before the regulator -> weaker but longer thump.
Since I'm toying with the PSU anyway, any suggestion on what the optimal voltage differences between the input & output stages ?
Another thing is, I'm having difficulties locating a good transformer here. I could order them custom made, any suggestion on what to specifiy ?
Cheers
Hi dutch,
I'm still changing the connection point & caps values. If I connect both stages after the regulator -> no thump,but if I connect both before the regulator -> weaker but longer thump.
Since I'm toying with the PSU anyway, any suggestion on what the optimal voltage differences between the input & output stages ?
Another thing is, I'm having difficulties locating a good transformer here. I could order them custom made, any suggestion on what to specifiy ?
Cheers
Re: Separate connection for output stages
Godam, as I use a single supply for input and output stages I've no experience in the determination of the optimal values of the voltages.
The transformer I will use in my current project is a 2x24V 330VA for each channel commercial-of-the-shelf available through www.schuro.de.
This should give roughly 33V unregulated (which is whitin limits of the 338K regulator) and I'll be operating the amp at 28-29 Volts.
In my first project I used 2x22V 225VA transformers.
godam said:
Godam, as I use a single supply for input and output stages I've no experience in the determination of the optimal values of the voltages.
The transformer I will use in my current project is a 2x24V 330VA for each channel commercial-of-the-shelf available through www.schuro.de.
This should give roughly 33V unregulated (which is whitin limits of the 338K regulator) and I'll be operating the amp at 28-29 Volts.
In my first project I used 2x22V 225VA transformers.
JLH input capacitor
Ralf,
The polystyrene capacitor I now use on the JLH input is 0.333uF which is available from Falcon Acoustics (UK) at a cost of £2. When I last visited their website is was to be found in the polypropylene capacitor section. I have tried two in parallel (0.666uF) but just one sounds better. The difference in bass response at 20Hz is so small as to be negligible.
Tim.
Ralf,
The polystyrene capacitor I now use on the JLH input is 0.333uF which is available from Falcon Acoustics (UK) at a cost of £2. When I last visited their website is was to be found in the polypropylene capacitor section. I have tried two in parallel (0.666uF) but just one sounds better. The difference in bass response at 20Hz is so small as to be negligible.
Tim.
Paper-in-oil vs Polystyrene
Erik,
The change from the MCap ('Audiophiler' polypropylene) to the A.N. copper foil p-in-o was large, the change from the p-in-o to the polystyrene was large also. It is possible to describe the two changes as travelling two sides of a triangle, starting with the MCap sounding accurate and clean though with some coldness and hardness, the p-in-o sounding warm and relaxed, very open with good clarity and powerful bass (its treble is still the best I have heard from any capacitor I have tried), the polystyrene sounding almost warmer still (glowing!) on a good recording through its substantially more accurate rendition of background ambience but also with greater detail overall than either of the others enabling easier involvement through listening. You could say that it has much of the best of both.
In short, they are very different, the A.N. p-in-o places emphasis on the width of stage, the polystyrene on the depth, the difference between them is very clear. For sheer detail and the ability to hear between the notes, the polystyrene is the obvious choice, but for a relaxed listen, without emphasis placed on the faults in a less than perfect recording the p-in-o is the one.
I was fortunate enough to have some 47nF p-in-o caps on hand when trying to decide which capacitor to keep in-circuit, wired in parallel with the polystyrenes this was enough to preserve enough of the p-in-o's wonderful treble quality, whilst retaining almost all of the polystyrene's remarkable clarity.
Tim.
Erik,
The change from the MCap ('Audiophiler' polypropylene) to the A.N. copper foil p-in-o was large, the change from the p-in-o to the polystyrene was large also. It is possible to describe the two changes as travelling two sides of a triangle, starting with the MCap sounding accurate and clean though with some coldness and hardness, the p-in-o sounding warm and relaxed, very open with good clarity and powerful bass (its treble is still the best I have heard from any capacitor I have tried), the polystyrene sounding almost warmer still (glowing!) on a good recording through its substantially more accurate rendition of background ambience but also with greater detail overall than either of the others enabling easier involvement through listening. You could say that it has much of the best of both.
In short, they are very different, the A.N. p-in-o places emphasis on the width of stage, the polystyrene on the depth, the difference between them is very clear. For sheer detail and the ability to hear between the notes, the polystyrene is the obvious choice, but for a relaxed listen, without emphasis placed on the faults in a less than perfect recording the p-in-o is the one.
I was fortunate enough to have some 47nF p-in-o caps on hand when trying to decide which capacitor to keep in-circuit, wired in parallel with the polystyrenes this was enough to preserve enough of the p-in-o's wonderful treble quality, whilst retaining almost all of the polystyrene's remarkable clarity.
Tim.