I measured many hundreds of lsk170.
I found lots of matched pairs which I sold on at low cost. All the b grade are sold. I still have a grade and c grade in swap meet.
But I did not find any matched quads.
Matching requires both Id and transconductance to be equal.
This is a very sensitive measurement and the chances of getting a quad set seem by my experience to be very low (zero quads from 300pairs)
However,
if you are ONLY selecting by Idss and completely ignoring gm, then it is very easy to select by Idss, so easy it is recommended regularly and by many to DIY.
You don't need to pay the exorbitant prices I see being asked for selected Idss pairs.
Out of a batch of 100 devices you will get at least 40pairs to better than 1% of Idss. The remaining pairs are likely to be better than 5%
= virtually no wastage.
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New owner here. Which resaistors exactly got most influence in sound? how many of them are most important?
I found 4 at output but see 8 of them
http://www.audiocircle.com/index.php?topic=85001.0
An externally hosted image should be here but it was not working when we last tested it.
I found 4 at output but see 8 of them
http://www.audiocircle.com/index.php?topic=85001.0
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The 220 Ohm ones are the more influential. Found in two pairs left and right to the output relay towards the PCB's center.
220R you meant? Next are 220k and least important 1M?
Thank you. In that case Ill try 4x220R and see if I hear difference first.
Is there any tolerance of value? Can I use 200R or 180R?
Thank you. In that case Ill try 4x220R and see if I hear difference first.
Is there any tolerance of value? Can I use 200R or 180R?
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The front row pairs near the PCB's edge flanking the signal output connector have two 220K and two 1Meg ones. Those are in parallel to the signal and less important. The 220R (Ohm) ones are in series to the signal, hence more important. All in all those eight are the only ones related to the L & R signal paths. You can use 200R instead of 220R.
Alright. What type of resistors you got there now? Have you listened to it already and in what kind of system?
Im not in hurry yet🙂 Just info for future.
Bought it assembled already and it looks like Takman metal film resistor.
DCB1->renovated Dynaco ST35->DIY speakers ScanSpeak 2608/913000 + Visaton AL130
Not ready now for changes though.
Bought it assembled already and it looks like Takman metal film resistor.
DCB1->renovated Dynaco ST35->DIY speakers ScanSpeak 2608/913000 + Visaton AL130
Not ready now for changes though.
Saw such posts before - I need to change some resistor right? I dont want to use monstrual heatsinks. Some small ones are preferred or maybe Id use bottom of case after putting DCB1 inside.
Thats hot rodded version right? Better sound overall? Better conditions for elements? Curious.
Thats hot rodded version right? Better sound overall? Better conditions for elements? Curious.
Those two pairs of resistors flanking the big electrolytic capacitors set the current flow in the MOSFETS. You can almost reach 200mA with 20R 2W replacing each of those resistors. No need for really hefty sinks, 200mA is just moderate hot-rod. The big semis run better with more current. You will need insulation pads though for common metal sinking between those MOSFETS. TO-247 sized Sil-Pads .
Trying to learn. So one 20R 2W resistor in place of 2 parallel ones right?
I found guideline for next step - 600mA. Smalll heatsinks (or moderate) would be still enough or Id kill Mosfets?🙂 Also is there need of changing MUR diodes for 820? I also noticed I got quite big transformer so it should be ok.
2A hot rod is beyond my imagination🙂
Thank you Salas - I will make small steps comparision. Maybe even increasing current to 200mA first🙂
I found guideline for next step - 600mA. Smalll heatsinks (or moderate) would be still enough or Id kill Mosfets?🙂 Also is there need of changing MUR diodes for 820? I also noticed I got quite big transformer so it should be ok.
2A hot rod is beyond my imagination🙂
Thank you Salas - I will make small steps comparision. Maybe even increasing current to 200mA first🙂
One 20R 2W in place of each now resistor in a pair, four in total, making 10R per side since in parallel. 600mA starts asking biggish ones and its suitable for DCB1 Hypnotize which has heftier bridge diodes and more PSU caps. You stop at 200mA. Which is the most popular step by the way.
Now everything is clear and sounds very reasonable. Ill post my impressions after increasing current to 200mA.
Technical question. I dont want to desolder MOSFETS.
1. Is there a problem if heatsink touches 20R resistor leg? If YES...
2. Would it be ok to mount heatsink upside down and get worse cooling for MOSFET?
If both cases are wrong ten maybe Id try to solder resistors at the bottom of PCB.
1. Is there a problem if heatsink touches 20R resistor leg? If YES...
2. Would it be ok to mount heatsink upside down and get worse cooling for MOSFET?
If both cases are wrong ten maybe Id try to solder resistors at the bottom of PCB.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
If there is no "electrical" contact, then no worries.
If there is electrical contact, then insert a thin electrical insulator.
If there is electrical contact, then insert a thin electrical insulator.
Solder 20R resistor on top of the other parallel 20R next to it which is further from the sink. Let an air gap between them. Or insulate the touching spot as Andrew said.
Don't mount those sinks upside down. Not enough MOSFET back contact. By the way the sinks are small, get bigger if you will have more than 70C on them.
Don't mount those sinks upside down. Not enough MOSFET back contact. By the way the sinks are small, get bigger if you will have more than 70C on them.
An externally hosted image should be here but it was not working when we last tested it.
I mounted resistor under PCB - maybe its even better for "cooling"?
Ummm I cant check temperature and I suppose organoleptic checking wouldnt be enough as 40- 50C could be hot for finger🙂
Both pair of MOSFETS get hot equally or I could get bigger heatsink for some pair? Im asking because I got bigger heatsinks but only 2 pcs🙂
if use the sink like that ..why you use High power mosfet ,...just use small type 1-2 Amp