ok, are you asure that to put the thermistor before the transformator is as good as to putt between primary when the transformer is 2x115?
Hi is it actually necessary to use thermistors or soft start? Today I don't use anything. When I tried thermistor I felt that something changed to negative. I lost a litle speed an resolution.
If a properly sized fuse (and I stress this) doesn't blow at a frequency to bother you without a thermistor/soft start then you don't need it.
If your fuse blows sufficiently often then you need something. It may be sometime as simple as a thermistor, or something more sophisticated that switches out the current limiting element after a short time.
If your fuse blows sufficiently often then you need something. It may be sometime as simple as a thermistor, or something more sophisticated that switches out the current limiting element after a short time.
Yeah, I think 4A is too high, going by the VA/ ac voltage rule of thumb.
If you don't like a thermistor, I suggest you look into a soft start with a relay.
If you don't like a thermistor, I suggest you look into a soft start with a relay.
I understand. with softstart I can probably go down to 2A. I have tried a cheap one from ebay but did not like it. I believe the switch and print need to be of good quality. Do you have suggestions for a good soft start?
Since you decided to experiment.... I strongly suggest that you read: "Capacitor Sounds" white papers from the Linear Audio website, in particular 4, 5 and 6 (which relate to amplifiers the most).
Here;s the VOl. 4 paper mentioned above. Pretty good reading! https://linearaudio.nl/sites/linear...an EW 11 2002 mar 2003 caps 100 nF to 1uF.pdf
Thanks. Read it. It may sink in. Haven't turned on the amp sense I installed the Elnas. How nothing smokes when I do.
Hey folks,
Been inspired by this thread, and doing a swift J build at the moment- a few outstanding Q's for you experts- PSU tested beautifully last night so now onto the amp boards and finishing touches:
- Bridged C1 as an improvement mentioned here
- left C6 and C7 out
- I see that Boky removes Q3, R13, and R14 in his schematic, which I take to be the short protection - in the images it looks like he's left one of the resistors in, and the other one-legged. I have those parts - wondering if someone could chime in on whether this is a bad move or not - doesnt seem to affect since his schematic reads well without these components.
Lastly, I picked up some 17W insulators that should out perform the Keratherm, but also picked up some of the alumina ceramic insulators in the right format that should perform even better around 24W dissipation. .... Has anyone implemented these before? Do they require compound between the mostfet/pad/heatsink - and if so, is it important to use a very high-performance compound?
At the risk of being slapped on the wrist, I'm building this in a 3U/300mm case with some external fans to help dissipate. Obviously will test around this - but the choices were motivated around the specific location the amp will live. So, definitely spending a little extra time and coin around the heat dissipation.
Been inspired by this thread, and doing a swift J build at the moment- a few outstanding Q's for you experts- PSU tested beautifully last night so now onto the amp boards and finishing touches:
- Bridged C1 as an improvement mentioned here
- left C6 and C7 out
- I see that Boky removes Q3, R13, and R14 in his schematic, which I take to be the short protection - in the images it looks like he's left one of the resistors in, and the other one-legged. I have those parts - wondering if someone could chime in on whether this is a bad move or not - doesnt seem to affect since his schematic reads well without these components.
Lastly, I picked up some 17W insulators that should out perform the Keratherm, but also picked up some of the alumina ceramic insulators in the right format that should perform even better around 24W dissipation. .... Has anyone implemented these before? Do they require compound between the mostfet/pad/heatsink - and if so, is it important to use a very high-performance compound?
At the risk of being slapped on the wrist, I'm building this in a 3U/300mm case with some external fans to help dissipate. Obviously will test around this - but the choices were motivated around the specific location the amp will live. So, definitely spending a little extra time and coin around the heat dissipation.
Ok I’m building a AJ there seems to be a good consensus that bridging c1 is a good idea... why are you leaving out c6-7?
There was mention that it wasnt "necessary" and if the board were revised they would be removed... more practically mouser is OOS on the .33nf Wima caps with 5mm spacing on leads, so i ordred the larger ones that I would be able to fit, unless I mount them on the back.
Boky's schematic calls for a 10nf I believe, which is in stock... I can always pop those in when I receive them.
This is less of an informed decision and more one arrived at through a combination of comments and parts availability.
Boky's schematic calls for a 10nf I believe, which is in stock... I can always pop those in when I receive them.
This is less of an informed decision and more one arrived at through a combination of comments and parts availability.
If you check the original schematics, you will realise that if Q3 is removed and the R14 and R13 junction is broken -> it's the same as removing ALL short circuit protection components from the PCB (electrically). So, that's what I did. Hence the R14 with one side lifted up. This makes R13 redundant: it's there on the PCB, but not connected at both ends (only at R19). The reason I removed the short circuit protection? Well, even though the Q3 has a very high resistance collector-emitter, the little JFET at the input needs all the help in this world to drive TWO MOSFETs (especially at high frequencies), so I gave it a bit of help by removing the Q3. In addition, my Dynaudio speakers are 4 ohms - I did not want to risk "opening" that Q3 at high currents running through R19 with low impedance speakers when listing at high volumes
The capacitors? The links I provided in my previous post explains which types, values and dielectric should be used for sound coupling, and which for power rails decoupling. It is an important read. Let is simmer for a while, look at the digital audio best-practices in decoupling, and then experiment a lot to arrive at the combination that suits your system and your taste the best.
The capacitors? The links I provided in my previous post explains which types, values and dielectric should be used for sound coupling, and which for power rails decoupling. It is an important read. Let is simmer for a while, look at the digital audio best-practices in decoupling, and then experiment a lot to arrive at the combination that suits your system and your taste the best.
Hey folks,
Just powered up the full amp after testing PSU overnight - seem to be having an issue thats showing itself as a smoky CL60 tied into ground block.
1, PSU tested "perfectly"
2. Mods are - C1 Bridged and C6 & 7 omitted - shouldnt relate, but worth mentioning
3. Q3, and R13, 14 omitted as well.
Checking everything over and over, and I can't find any particular culprits at the moment - the ony clarification:
Channel 1 - I have solid connections from V+, V- and GND. and ALL THREE show continuity when tested against star ground or base plate.
Channel 2 - I have the same behavior EXCEPT V+ does not chime conitnuity to star ground/Baseplate
on the PSU Board, I get continuity from V+ to GND to V- as well, but seems normal.
Any targeted thoughts for troubleshooting? Should I take this to another thread? finally, Could this be that the CL60 is poorly rated for the mods and start-up current needs?
**** QUICK EDIT*** - After retesting the PSU board, it seems that the solder grounds on the connection block are weak - while I get my ~+/- 25V when going to the ground leading to star, I am not getting a nice ground when going to other two - going to reflow these after it's drained out, and see how we do.
Thanks in advance
Just powered up the full amp after testing PSU overnight - seem to be having an issue thats showing itself as a smoky CL60 tied into ground block.
1, PSU tested "perfectly"
2. Mods are - C1 Bridged and C6 & 7 omitted - shouldnt relate, but worth mentioning
3. Q3, and R13, 14 omitted as well.
Checking everything over and over, and I can't find any particular culprits at the moment - the ony clarification:
Channel 1 - I have solid connections from V+, V- and GND. and ALL THREE show continuity when tested against star ground or base plate.
Channel 2 - I have the same behavior EXCEPT V+ does not chime conitnuity to star ground/Baseplate
on the PSU Board, I get continuity from V+ to GND to V- as well, but seems normal.
Any targeted thoughts for troubleshooting? Should I take this to another thread? finally, Could this be that the CL60 is poorly rated for the mods and start-up current needs?
**** QUICK EDIT*** - After retesting the PSU board, it seems that the solder grounds on the connection block are weak - while I get my ~+/- 25V when going to the ground leading to star, I am not getting a nice ground when going to other two - going to reflow these after it's drained out, and see how we do.
Thanks in advance
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