ok, thank all of you for your answers. Just i am afraid its the first time with snouber boards.
Hi X,
Some questions before I order some parts for the AN.
1. Are the Silmic caps at C111, C131, C132 essential. I have a UCC 100uF 63V rather
than a 50V for C111 and 2 x UCC 220uF 63V rather than 35V for C131,132.
2. Which to use KSC3503 or TTC004B for V115 (ie:any difference)
3. Which to use KSA992 or BD140 for V131 (ie: any difference)
4. All my LED's are in the 1.7 - 1.8V range. Are these OK, or do I need the 2V ones.
Thanks,
MM
Some questions before I order some parts for the AN.
1. Are the Silmic caps at C111, C131, C132 essential. I have a UCC 100uF 63V rather
than a 50V for C111 and 2 x UCC 220uF 63V rather than 35V for C131,132.
2. Which to use KSC3503 or TTC004B for V115 (ie:any difference)
3. Which to use KSA992 or BD140 for V131 (ie: any difference)
4. All my LED's are in the 1.7 - 1.8V range. Are these OK, or do I need the 2V ones.
Thanks,
MM
Hi Myles,
I don’t have a lot of time to answer this right now. Maybe Hugh can help. I’ll try my best with broad strokes below.
I don’t have a lot of time to answer this right now. Maybe Hugh can help. I’ll try my best with broad strokes below.
Hi Myles,
XRK is quite right!
I would only use KSC3503, easy to get; Fairchild. You can use KSC2682 as well but becoming obsolete.
Yes, very different beasts. If you can't use A992, use the 2N5401 (On semi) which is easier to get. BUT WATCH THE PINOUTS, they are different.
Generally this is a GREEN led. They will do 1.95V at 3mA but rarely below 1.85V. any green will be fine as long as it is specced at no more than 20mA.
HD
XRK is quite right!
I would only use KSC3503, easy to get; Fairchild. You can use KSC2682 as well but becoming obsolete.
Yes, very different beasts. If you can't use A992, use the 2N5401 (On semi) which is easier to get. BUT WATCH THE PINOUTS, they are different.
Generally this is a GREEN led. They will do 1.95V at 3mA but rarely below 1.85V. any green will be fine as long as it is specced at no more than 20mA.
HD
Thanks Hugh and X,
1. I just found the note between garys and X. X recommends the KSA992 at
V131. Then X writes that BD140 should work with correct pinouts.
2. I have some KSA992's to use, but want to make sure it is correct, otherwise
I will order BD140.?
3. I have the KSC3503, so no problem for V113.
4. Is it recommended to install a trimpot for adjusting offset (increase value of
R113)?
5. PS Hugh, sent you an email about substitute for FQA40N25. None at Mouser
or Digikey
Thanks for the help,
Myles
1. I just found the note between garys and X. X recommends the KSA992 at
V131. Then X writes that BD140 should work with correct pinouts.
2. I have some KSA992's to use, but want to make sure it is correct, otherwise
I will order BD140.?
3. I have the KSC3503, so no problem for V113.
4. Is it recommended to install a trimpot for adjusting offset (increase value of
R113)?
5. PS Hugh, sent you an email about substitute for FQA40N25. None at Mouser
or Digikey
Thanks for the help,
Myles
Hi Myles,
Please don't use BD140 in place of the A992. The BD140 is at the output stage and chosen for its SLOW performance - it's a large chip and it will prevent oscillation at the output current sensor transistor.
If you are concerned about offset, yes, use a trimmer. Many people are quite concerned about offset, but in truth you can tolerate up to 50mV plus of minus with no damage to the speaker and no effect at all on the sound quality. It's nice to get it down to sub 1mV, but it's not needed in truth.
I have sent you a list of 11 suspects to replace the FQA40N25, and about six are presently available at Digikey. Mouser will no doubt have some of them too. You need an inexpensive nmos with AT LEAST 100V, 25A, TO247/TO3P, Rds <100mohms, and less than gate capacitance of 5nF. This is a reasonably easy requirement, and no unobtainium needed here.......
Best of luck with the build, Myles!
Hugh
Please don't use BD140 in place of the A992. The BD140 is at the output stage and chosen for its SLOW performance - it's a large chip and it will prevent oscillation at the output current sensor transistor.
If you are concerned about offset, yes, use a trimmer. Many people are quite concerned about offset, but in truth you can tolerate up to 50mV plus of minus with no damage to the speaker and no effect at all on the sound quality. It's nice to get it down to sub 1mV, but it's not needed in truth.
I have sent you a list of 11 suspects to replace the FQA40N25, and about six are presently available at Digikey. Mouser will no doubt have some of them too. You need an inexpensive nmos with AT LEAST 100V, 25A, TO247/TO3P, Rds <100mohms, and less than gate capacitance of 5nF. This is a reasonably easy requirement, and no unobtainium needed here.......
Best of luck with the build, Myles!
Hugh
Hopefully these MOSFETS are also good substitutions. They are all available at Mouser:
Alpha Nirvana 39w 8ohm Class A Amp
Best,
Anand.
Alpha Nirvana 39w 8ohm Class A Amp
Best,
Anand.
Hi Hugh, and other Nirvana builders,
Something is not sitting with me very well. The KSA992 are at the LTP, no problem there.
In some schematics V131 is shown as a KS992 (is this the same as a KSA992?) and sometimes as a BD140. Hugh, your cct in post #88 shows a BD140 for V131.
X also wrote that he used a BD140 for V131, but also showed on his "as built" schematic a KS992 for V131 in red letters.
All I would like is a confirmation of what component to use at V131.
Thanks,
Myles
Something is not sitting with me very well. The KSA992 are at the LTP, no problem there.
In some schematics V131 is shown as a KS992 (is this the same as a KSA992?) and sometimes as a BD140. Hugh, your cct in post #88 shows a BD140 for V131.
X also wrote that he used a BD140 for V131, but also showed on his "as built" schematic a KS992 for V131 in red letters.
All I would like is a confirmation of what component to use at V131.
Thanks,
Myles
Hi Myles,
So sorry for the confusion!
It’s been a long time since I built this amp. Maybe 6 or 7 amps ago? Indeed it looks like I used KSA992 at V131. I am not sure why now - I can’t remember the reason.
The pin outs of KSA992 and BD140 are the same - ECB. 🙂
So sorry for the confusion!
It’s been a long time since I built this amp. Maybe 6 or 7 amps ago? Indeed it looks like I used KSA992 at V131. I am not sure why now - I can’t remember the reason.
The pin outs of KSA992 and BD140 are the same - ECB. 🙂
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Hi X,
I'm wondering if some people looking at the first post, might be interested if you also included a reference to the lower 20W powered version there as well.
Discussion begins here: Alpha Nirvana 39w 8ohm Class A Amp
I'm wondering if some people looking at the first post, might be interested if you also included a reference to the lower 20W powered version there as well.
Discussion begins here: Alpha Nirvana 39w 8ohm Class A Amp
In the sim v131 is running at 30mW, so definitely small transistor will be perfect here.
In my build I used 2N5401, and it worked perfectly.
In my build I used 2N5401, and it worked perfectly.
Alpa Nirvana build.
My cases should arrive in a few days and I will be able to build up this amp. First thanks to The design team, Hugh for sharing his intellectual material and being a consonant gentleman, X - I don’t know how he does it, I thought I was productive in my heyday but can’t hold a candle to him, JPS for state of the art layout, and last but not least Vunce for doing the sanity test builds. What makes this project so special to me is not only a great design but also I will be able to duplicate the proof as I am learning to use REW to confirm results ( thanks X for your post on using it. My plan is kinda backwards from most builds I will have in one box dual mono power supplies and the amps in their own enclosures with fan cooled cpu heat sinks. I would have likes to use transformers with multiple outs but Anteks are cheap and I have a collection started, this way I will get more use out of this fine power supply(SMLB of course). I went fullMomty on this with SLF soft start,SLB power supplies, Alpha boards, and RTR SSR speaker protection.
My cases should arrive in a few days and I will be able to build up this amp. First thanks to The design team, Hugh for sharing his intellectual material and being a consonant gentleman, X - I don’t know how he does it, I thought I was productive in my heyday but can’t hold a candle to him, JPS for state of the art layout, and last but not least Vunce for doing the sanity test builds. What makes this project so special to me is not only a great design but also I will be able to duplicate the proof as I am learning to use REW to confirm results ( thanks X for your post on using it. My plan is kinda backwards from most builds I will have in one box dual mono power supplies and the amps in their own enclosures with fan cooled cpu heat sinks. I would have likes to use transformers with multiple outs but Anteks are cheap and I have a collection started, this way I will get more use out of this fine power supply(SMLB of course). I went fullMomty on this with SLF soft start,SLB power supplies, Alpha boards, and RTR SSR speaker protection.
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Ok my first question will be wire routing, I have some nice 4 pin amp plugs that will accommodate 14 ga wire I think will work well to tie 28-0-28 with chassis ground. The second requirement will be 12v for the fans and their active controllers and a temp meter on the front of the case. I am on the fence powering the RTR SSR boards from the SLF soft start, I may just hold off and see if there is a turn off thump. My main goal is to recreate the sonic signature Hugh and X have built into this design. My favorite amps ( my builds) are mostly Class A and I feel this one will fall in quite nicely into my quiver of amps. I will post pictures when I start to stuff the boards into boxes in the mean time I am practicing with tomato’s and a can, I always end up with a tight fit and layout is a challenge not to compromise ground loops and other pesty things.
Bill
Bill
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By the way no drama on power up of boards, I have to admit I was a little concerned. Initial power up of the Nirvana on my bench supply was able to provide 1khz test tone from N3 player ( again thanks X) - nice clean waveform on scope, clips where it should and light indicates. Ran it close to max output into heat sinks for 20 minutes main heat sink cooled down from idling temps. Gave a brief listening test bass was well controlled , the highs may need a little burn in time and my test bench connections all need to be cleaned as I do have a little cracking noice when switches and connection moved.
Bill
Bill
Hello all,
For C125, can a CD15 10pF 500v mica cap be used or a Vishay 10pF 1KV ceramic disc cap which is a bit cheaper.
Thanks,
MM
For C125, can a CD15 10pF 500v mica cap be used or a Vishay 10pF 1KV ceramic disc cap which is a bit cheaper.
Thanks,
MM
MM,
My understanding is that a silver mica cap would be better in that position if using a through hole component. The alternative is the SMD 1206 MLCC part.
Are you using Andyr's bill of materials that X has linked to in the first post? The parts listed there are 15 pF and not 10 pF.
I checked the 8R version and it has a 15pF part (CD15CD150J03F) listed that is available from Mouser @ $1.95. There is a similar part (CD15CD150J03) that is slightly less expensive @ $ 1.33 and should also work.
My understanding is that a silver mica cap would be better in that position if using a through hole component. The alternative is the SMD 1206 MLCC part.
Are you using Andyr's bill of materials that X has linked to in the first post? The parts listed there are 15 pF and not 10 pF.
I checked the 8R version and it has a 15pF part (CD15CD150J03F) listed that is available from Mouser @ $1.95. There is a similar part (CD15CD150J03) that is slightly less expensive @ $ 1.33 and should also work.
Thanks ZMan,
I am using X's as built schematic as in Post 1551. You can see the brown cap between the 2 brown electro's. The schematic shows the C1250 option as a 10p 500V CD15. The only smd parts I will use are C133,C134, C171.
Mouser has 10pf 500V mica's 598-CD15CD100DO3F
The 15pF mica is at C114, on the schematic.
Cheers,
MM
I am using X's as built schematic as in Post 1551. You can see the brown cap between the 2 brown electro's. The schematic shows the C1250 option as a 10p 500V CD15. The only smd parts I will use are C133,C134, C171.
Mouser has 10pf 500V mica's 598-CD15CD100DO3F
The 15pF mica is at C114, on the schematic.
Cheers,
MM