Hi ddanbo,
As silly as that sounds, capacitors (for example) that are too large end up ripping the pads and traces as they break free. Also consider that a large capacitor will pick up more noise as it gets larger in size. You might even create and oscillation problem.
-Chris
Use parts that fit, or can be secured to the PCB.
As silly as that sounds, capacitors (for example) that are too large end up ripping the pads and traces as they break free. Also consider that a large capacitor will pick up more noise as it gets larger in size. You might even create and oscillation problem.
-Chris
Hi anatech,
Thanks for the advice, you are correct, there is not a lot of physical room to fit this cap in and the space available at the pad locations is not tremendous either - one of the reasons I was not looking forward to a lot of swapping of parts for experimentation.
From some of the pics I've looked at (one attached from Dick West I believe), it looks like behind the board (between the board and the heatsink) appears to be the best spot. Perhaps hot glue or silicone to secure the cap?
I should not be so fussed about shooting for a specific value then? Go for best fit then with a value somewhere in the middle?
I believe the original design cap was a 10mfd 16V NP
Thanks for the advice, you are correct, there is not a lot of physical room to fit this cap in and the space available at the pad locations is not tremendous either - one of the reasons I was not looking forward to a lot of swapping of parts for experimentation.
From some of the pics I've looked at (one attached from Dick West I believe), it looks like behind the board (between the board and the heatsink) appears to be the best spot. Perhaps hot glue or silicone to secure the cap?
I should not be so fussed about shooting for a specific value then? Go for best fit then with a value somewhere in the middle?
I believe the original design cap was a 10mfd 16V NP
Attachments
Hi ddanbo,
I really don't like the way those supply filter caps are mounted at all. Strictly garage work there!
As far as I'm concerned, replacement parts should be capable of fitting in the original space, new lead holes are fine. "Flying" parts are a sign of poor workmanship. If you find that you need to use a larger component, make a new PCB, because there will be other things you will be changing as well.
-Chris
I really don't like the way those supply filter caps are mounted at all. Strictly garage work there!
As far as I'm concerned, replacement parts should be capable of fitting in the original space, new lead holes are fine. "Flying" parts are a sign of poor workmanship. If you find that you need to use a larger component, make a new PCB, because there will be other things you will be changing as well.
-Chris
Input caps
Hi ddanbo, have you considered using a stacked metallised film cap by EPCOS
these are very small caps of very low inductance.. as an example a 4.7 uf is only
9mm W 11mm H 9.8mm D with lead spacing 7.5 and is rated at 63v, these are easily
mounted on the edge of the Hafler board by drilling lead size holes and hard wiring
I am looking at the RS catalogue part number 191-3373 this is the largest size in this
series.. next question, how good? well NAIM used these as the timing caps around
their 1541 DAC, and were just as good as highly selected polypropylenes used in updated Marantz and Philips top of the range CD players precisely because of their very low inductance, in fact I have used block film caps in some of my xover designs
because the square configuration [blocks] give rise to lower inductance figures,
whereas those SOLENS are round bulky beasts and are not in my opinion all that they are cracked up to be, unless you go for the very best foils, as opposed to metalized film. Anatech is right to express caution with these larger caps too near the
O/P Mosfets as instability can result etc .
regards
Hi ddanbo, have you considered using a stacked metallised film cap by EPCOS
these are very small caps of very low inductance.. as an example a 4.7 uf is only
9mm W 11mm H 9.8mm D with lead spacing 7.5 and is rated at 63v, these are easily
mounted on the edge of the Hafler board by drilling lead size holes and hard wiring
I am looking at the RS catalogue part number 191-3373 this is the largest size in this
series.. next question, how good? well NAIM used these as the timing caps around
their 1541 DAC, and were just as good as highly selected polypropylenes used in updated Marantz and Philips top of the range CD players precisely because of their very low inductance, in fact I have used block film caps in some of my xover designs
because the square configuration [blocks] give rise to lower inductance figures,
whereas those SOLENS are round bulky beasts and are not in my opinion all that they are cracked up to be, unless you go for the very best foils, as opposed to metalized film. Anatech is right to express caution with these larger caps too near the
O/P Mosfets as instability can result etc .
regards
Thanks for the replies!
I was able to mount a 3.9 mfd solen PA series to the back of the board similar to the pic in my previous post. The cap seems sturdy enough (cap is quite light) and the lead holes did not need to be enlarged.
The soudstage has definetly opened up and overall sounds good - then again I have less than 8 hours on it so far.
Humble - thanks for the sugestion and I would be interested in giving it a go, but a quick search shows these caps generally not available this side. Is Digikey part # 495-1131-ND comparable? The lead spacing is much larger, but could be installed as you suggest.
I was able to mount a 3.9 mfd solen PA series to the back of the board similar to the pic in my previous post. The cap seems sturdy enough (cap is quite light) and the lead holes did not need to be enlarged.
The soudstage has definetly opened up and overall sounds good - then again I have less than 8 hours on it so far.
Humble - thanks for the sugestion and I would be interested in giving it a go, but a quick search shows these caps generally not available this side. Is Digikey part # 495-1131-ND comparable? The lead spacing is much larger, but could be installed as you suggest.
ddanbo,
The digikey 495-1131 is the same as the RS 335-101 and has the same 15mm pins and is the same B32522 material.
There is another smaller one called 495-1110 that has the 5mm pins but uses the B32529 material and so may not give the same sound. If it's any relevance, these ones are very cheap (about 15c each)
All these caps are Epcos 63v stacked film.
- the newer numbered RS 483-3955 is called a 'stacked coin' (?) and the RS 335-101 (D'key 495-1131-ND) is the traditional radial style - the 'stacked coin' ones seem to have very short legs.
The digikey 495-1131 is the same as the RS 335-101 and has the same 15mm pins and is the same B32522 material.
There is another smaller one called 495-1110 that has the 5mm pins but uses the B32529 material and so may not give the same sound. If it's any relevance, these ones are very cheap (about 15c each)
All these caps are Epcos 63v stacked film.
- the newer numbered RS 483-3955 is called a 'stacked coin' (?) and the RS 335-101 (D'key 495-1131-ND) is the traditional radial style - the 'stacked coin' ones seem to have very short legs.
I/P caps
Hi ddanbo, I am not familiar with the brand "Digikey" caps and so cannot give a definitive answer, however the descriptive construction of that type should indicate
any similarities. The essential thing is that the stacked metallised film caps are different in that the cap is made up of layers of plates instead of a two plate roll-up
arrangement as in the Solens this is what gives rise to the lower inductance, in other words the roll-up represents effectively "coils" with a consequential inductance, for most audio applications this does not represent a degradation in sound quality, but
I am explaining that a smaller block type of cap will also not cause a degradation either just because it is not "Polypropylene", further these Epcos, also made by Siemens can be obtained in much smaller working voltages whereas the Solens do mainly two ranges one at 250volts and the other at 400volt, some of the smaller values do come in at 630volts.. Since the original cap was only rated at 16volts
it follows that there is going to be an unnecessary size differential, so one looks for a cap to fulfill all the requirements necessary without cluttering the board. The nice thing about the Epcos was that it is available at 63volts is small in size, but the 100volt range is only offered up to 2.2UF. In all events you seem to have managed a solution with the 3.9UF solen which will give an adequate bass performance, and provided you have no instability problems can leave as it is. Should you do get such a problem there is a simple solution commonly used in in "Mosfet" amps which is easily implemented, just get back to me as necessary, remember to give the new components time to settle and enjoy your new "Disembodied liquid depth"
of sound if you'll pardon the euphemism
Regards
Hi ddanbo, I am not familiar with the brand "Digikey" caps and so cannot give a definitive answer, however the descriptive construction of that type should indicate
any similarities. The essential thing is that the stacked metallised film caps are different in that the cap is made up of layers of plates instead of a two plate roll-up
arrangement as in the Solens this is what gives rise to the lower inductance, in other words the roll-up represents effectively "coils" with a consequential inductance, for most audio applications this does not represent a degradation in sound quality, but
I am explaining that a smaller block type of cap will also not cause a degradation either just because it is not "Polypropylene", further these Epcos, also made by Siemens can be obtained in much smaller working voltages whereas the Solens do mainly two ranges one at 250volts and the other at 400volt, some of the smaller values do come in at 630volts.. Since the original cap was only rated at 16volts
it follows that there is going to be an unnecessary size differential, so one looks for a cap to fulfill all the requirements necessary without cluttering the board. The nice thing about the Epcos was that it is available at 63volts is small in size, but the 100volt range is only offered up to 2.2UF. In all events you seem to have managed a solution with the 3.9UF solen which will give an adequate bass performance, and provided you have no instability problems can leave as it is. Should you do get such a problem there is a simple solution commonly used in in "Mosfet" amps which is easily implemented, just get back to me as necessary, remember to give the new components time to settle and enjoy your new "Disembodied liquid depth"
of sound if you'll pardon the euphemism
Regards
Hi humble,
Digikey is simply a distributer of parts, like Farnell (that would be Newark here in North America). They are known for very fast delivery and reasonable shipping rates.
Epcos is the brand, so they are the same parts you are looking at. The Epcos number would be the same in both places.
-Chris
Digikey is simply a distributer of parts, like Farnell (that would be Newark here in North America). They are known for very fast delivery and reasonable shipping rates.
Epcos is the brand, so they are the same parts you are looking at. The Epcos number would be the same in both places.
-Chris
Heatsink Rating of DH200
Hi Woody the estimation of 0.5 degree C per watt is pretty accurate, but easy to check.
If you can use a temperature probe and use with your digital meter just take a measurement in the quiescent state, deduct the room ambient temperature, this should leave you with a reading of around 17degree's C this is relative to the
quiescent current set at 275ma times the plus and minus supplies at 124volts, which is 34watts dissipated in each heatsink if the heatsink is 0.5degrees as estimated, then
34watts multiplied by by 0.5 will equal 17 degrees per watt ..when you add the ambient temp of say 25degrees you will have the final heatsink temp at 42degreesC
Since the Whole quiescent power for this amp is 100VA which includes all losses
and early stage power consumption it is clear that the total power dissipated in each
power amp must be much less than 50watts per side, agreeing pretty well with the calculated values of around 34watts..Of course some of the earlier amps had a higher quiescent current, maybe they drifted that way, but I suspect that since the modules were preset at the factory, there will have been a fair spread of quiescent currents simply because every module would have settled differently in a different time frame
since these kits had to be dispatched to a large order book, but it is easy to interpolate by knowing the three variables, your quiescent current the DC supply voltage and the ambient temperature..
Hope this helps
regards
Hi Woody the estimation of 0.5 degree C per watt is pretty accurate, but easy to check.
If you can use a temperature probe and use with your digital meter just take a measurement in the quiescent state, deduct the room ambient temperature, this should leave you with a reading of around 17degree's C this is relative to the
quiescent current set at 275ma times the plus and minus supplies at 124volts, which is 34watts dissipated in each heatsink if the heatsink is 0.5degrees as estimated, then
34watts multiplied by by 0.5 will equal 17 degrees per watt ..when you add the ambient temp of say 25degrees you will have the final heatsink temp at 42degreesC
Since the Whole quiescent power for this amp is 100VA which includes all losses
and early stage power consumption it is clear that the total power dissipated in each
power amp must be much less than 50watts per side, agreeing pretty well with the calculated values of around 34watts..Of course some of the earlier amps had a higher quiescent current, maybe they drifted that way, but I suspect that since the modules were preset at the factory, there will have been a fair spread of quiescent currents simply because every module would have settled differently in a different time frame
since these kits had to be dispatched to a large order book, but it is easy to interpolate by knowing the three variables, your quiescent current the DC supply voltage and the ambient temperature..
Hope this helps
regards
Anyone had any problems with the DC offset 1K trimpots? I have been unable to fix some dc offset drift in one channel of one of my P230's. Now i can't get the offset to settle below ~60mV and it jumps around a lot - between 50mV and 300mV. One tap on the trimpot and the offset will jump all over the place. I've redone the solder joints, with no difference leading me to believe the pot itself is bad.
Anyone got a suitable replacement part number?
Anyone got a suitable replacement part number?
Looking through the DH 220 manual it describes a technique for setting DC Offset with P1 and a technique for setting bias current using P2... This works, I have seen it with my own eyes.
Fine and dandy. Well, for my DH 500, (which allegedly has identical circuitry) the manual has no reference for setting DC Offset, and it states that P1 is for setting bias???
What do I do?
Also, I have seen recommended settings for Bias from as low as the 275 mA setting from the DH220 manual, to 500 mA here in this thread.
The DH 500 manual mentions no recommendations...
Any help out there?
Thanks,
BTW... great thread.
Fine and dandy. Well, for my DH 500, (which allegedly has identical circuitry) the manual has no reference for setting DC Offset, and it states that P1 is for setting bias???
What do I do?
Also, I have seen recommended settings for Bias from as low as the 275 mA setting from the DH220 manual, to 500 mA here in this thread.
The DH 500 manual mentions no recommendations...
Any help out there?
Thanks,
BTW... great thread.