I've made the "plunge",too!!
Now that I have these awesome boards, all will be easy..... my experience in sourcing the right "stuff" at the lowest price will be valuable.(I will share)
My first impressions are that these boards are top quality. The resulting amp will dependent on what components are chosen for it.
The gain match of the 1381 and the 3503 is futile. the 3503's are just doing "CCS work". The 1381 is the "star player" .. It's gain (along with it's driver) , is what you hear. 10K gain + (close to) no load on the cascode is the "trick" that the "blameless" topology utilizes to achieve near zero distortion.
PS - on a current sourced amp , the CCS is a fully separate entity . You could use lamearse devices for the CCS , as long as the darlington- active (1381-ksa992) pair is there. 10K+ of gain +NFB is what makes the" blameless" rock!!
OS
Now that I have these awesome boards, all will be easy..... my experience in sourcing the right "stuff" at the lowest price will be valuable.(I will share)
My first impressions are that these boards are top quality. The resulting amp will dependent on what components are chosen for it.
The gain match of the 1381 and the 3503 is futile. the 3503's are just doing "CCS work". The 1381 is the "star player" .. It's gain (along with it's driver) , is what you hear. 10K gain + (close to) no load on the cascode is the "trick" that the "blameless" topology utilizes to achieve near zero distortion.
PS - on a current sourced amp , the CCS is a fully separate entity . You could use lamearse devices for the CCS , as long as the darlington- active (1381-ksa992) pair is there. 10K+ of gain +NFB is what makes the" blameless" rock!!
OS
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Excellent! That’d be a great help to amateurs such as myself in identifying the best quality
components. Look forward to seeing the outcome.Good to hear – I’m now close to pushing the “buy button”
Thanks for that. So for the 1381 you’d recommend the highest gain available? SA1381E (hfe 100-200) is best I can find - is that good enough? Or would the MJE340/350 combo (hfe 30-240) be a better bet?[/COLOR]
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Either a high gain 1381 OR a high gain 992 will suffice. The ideal is for BOTH Hfe's to be as high as possible.
200(1381-F or E) x 400(ksa992-F or E)=80k. 8ma/80k = about a .1 uA(.0000001A) load on the current mirror. In real life this might be higher, (flux ,the board,or loading by the drivers).
OS
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Proposed updated schematic?
OStripper,
What do you think of this proposed and minor collection of updates?:
http://www.diyaudio.com/forums/atta...746574-diyab-amp-honey-badger-honeybadger.gif
There's a few different devices, much easier matching, one different cap value (for cleaner deeper bass) and hopefully non-explosive, constrained trimmer settings. Are there any errors on that schematic? Can we indeed dial the potentiometers shown to Any setting and not burst the outputs, or do those potentiometer variables need reworked again?
OStripper,
What do you think of this proposed and minor collection of updates?:
http://www.diyaudio.com/forums/atta...746574-diyab-amp-honey-badger-honeybadger.gif
There's a few different devices, much easier matching, one different cap value (for cleaner deeper bass) and hopefully non-explosive, constrained trimmer settings. Are there any errors on that schematic? Can we indeed dial the potentiometers shown to Any setting and not burst the outputs, or do those potentiometer variables need reworked again?
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OOPS! did I already make a bad decision?
Daniel's updated schematic says "no ON Semi small or medium signal devices -- Please use Fairchild and/or Toshiba." for 4R loads. I'd like to be able to drive 4R loads. My speakers are rated as "6 ohms nominal, 4 ohms minimum". I already purchased the ON Semiconductor NJW0302G and NJW0281G, both rated at 150W. My transformer is 800VA, 35V secondaries, so I could potentially drive them beyond their 450 watt (150 X3) rating. But then, I don't play music very loud. Is it worth getting higher rated output transistors?
Daniel's updated schematic says "no ON Semi small or medium signal devices -- Please use Fairchild and/or Toshiba." for 4R loads. I'd like to be able to drive 4R loads. My speakers are rated as "6 ohms nominal, 4 ohms minimum". I already purchased the ON Semiconductor NJW0302G and NJW0281G, both rated at 150W. My transformer is 800VA, 35V secondaries, so I could potentially drive them beyond their 450 watt (150 X3) rating. But then, I don't play music very loud. Is it worth getting higher rated output transistors?
That representation of what the footnote says is definitely a misquote.
For small signal and medium signal (driver) transistors, there is currently a production problem with OnSemi's purchase of a new fab plant, and this is causing gross mismatch when big vendors stock compliments from differing production. And, they did!
Fairchild would be more predictable for small signal.
So far, OnSemi large output devices are not affected, so don't be confused. The OnSemi output devices work just fine.
The combination looks just fine for home replay. Basically, the fuses protect the amp; however, your oversize transformer doesn't protect the fuses.
The only error I can see is if it was used for a music production amplifier, you'd need to choose a lower VA transformer in order to prevent the fuses from breaking a concert.
For small signal and medium signal (driver) transistors, there is currently a production problem with OnSemi's purchase of a new fab plant, and this is causing gross mismatch when big vendors stock compliments from differing production. And, they did!
Fairchild would be more predictable for small signal.
So far, OnSemi large output devices are not affected, so don't be confused. The OnSemi output devices work just fine.
In this case, the triple parallel outputs should work fine when the transformer has 35v secondaries.
The combination looks just fine for home replay. Basically, the fuses protect the amp; however, your oversize transformer doesn't protect the fuses.
The only error I can see is if it was used for a music production amplifier, you'd need to choose a lower VA transformer in order to prevent the fuses from breaking a concert.
What I'd like to know is: Did I successfully alter the schematic trimmer values to remove explosion settings but retain useful settings?
Hi Daniel,
The complementary pair for MJL1302 should be MJL3281 as in
http://www.onsemi.cn/pub_link/Collateral/MJL3281A-D.PDF
I am using 3 pairs of NJW1302/NJW3281 with driver of 2SC5171/2SA1930 pairs on 4 ohms speakers with 800VA toriod and 20kuF capacitor on each line. They are running fine. I just burnned a few fuses due to the bias current set more than 35mV on 0.22ohm resistor. (I think the the amp can handle more power if the fuse can set higher.) Currently the bias current is set to 22mV on 0.22ohm resitor without any failure on fuse for few months. I had bad experience only on the mouting of the transistors even with aluminium bar clamp on top. If they are not totally contacted or in parallel with heatsink, the amp still had surged in current. Luckily, the transistors didn't cook as I offed the amp instantly.
MJL version definitely will have better power control as compare to NJW version in my opinion.
James
The complementary pair for MJL1302 should be MJL3281 as in
http://www.onsemi.cn/pub_link/Collateral/MJL3281A-D.PDF
I am using 3 pairs of NJW1302/NJW3281 with driver of 2SC5171/2SA1930 pairs on 4 ohms speakers with 800VA toriod and 20kuF capacitor on each line. They are running fine. I just burnned a few fuses due to the bias current set more than 35mV on 0.22ohm resistor. (I think the the amp can handle more power if the fuse can set higher.) Currently the bias current is set to 22mV on 0.22ohm resitor without any failure on fuse for few months. I had bad experience only on the mouting of the transistors even with aluminium bar clamp on top. If they are not totally contacted or in parallel with heatsink, the amp still had surged in current. Luckily, the transistors didn't cook as I offed the amp instantly.
MJL version definitely will have better power control as compare to NJW version in my opinion.
James
Honeybadger build - observations, comments and advice
Well I’ve nearly completed populating my HB boards and I thought it worth sharing my experiences thus far.
• First off the DIYAudio boards are great quality! Don’t even bother trying to etch your own unless you’re a die-hard DIY enthusiast!
• As noted earlier by others, some of the holes are too small and need to be drilled out – a bit of a shame destroying those beautiful through hole plated pads. I’m sure my experience will be different to others – it will depend on where you are and your choice of components but maybe making some of those really small ones a little bigger in future production runs could make it easier for DIYers
• C18 and C19 solder pads are unfortunately lacquered over. I had to scrape the laquer off in order to solder the components in place. Same for CRZ jumpers. Maybe this can be corrected in next production runs
• Be patient, take your time and check, double check and check your work again – it’s a bit of a mind-numbing job and so easy to mount some components the wrong way round. I’ve had to de-solder and remount 1 or 2 components on the way, despite making sure I was putting them in the right way first time round! (or so I thought...)
• Here in the UK Mouser seems to be the best source for most components, but they don’t have everything. I sourced from a variety of places Farnell, HiFiCollective, ModulusAmplification and Toby Electronics covered everything I needed.
• I’m mounting the boards directly onto those big and beautiful (4U) HFi2000 heatsinks. I’ve drilled and tapped my own heat sink mounting holes using a small hand drill and good quality M3 middle tap & holder (i.e ~ £15! - watch out for some of the Chinese rubbish floating around out there). This task proved to be easy and simple – just make sure you use DIYAudios very useful universal mounting specification
That’s it for now – I eagerly await supply of the PSU boards to become available
– in the meantime I’m finishing off the amplifier boards, soft starts, speaker protection boards and also building a simple, programmable IR remote control receiver to manage power on/off for this baby.
Well I’ve nearly completed populating my HB boards and I thought it worth sharing my experiences thus far.
• First off the DIYAudio boards are great quality!
Don’t even bother trying to etch your own unless you’re a die-hard DIY enthusiast!• As noted earlier by others, some of the holes are too small and need to be drilled out – a bit of a shame destroying those beautiful through hole plated pads. I’m sure my experience will be different to others – it will depend on where you are and your choice of components but maybe making some of those really small ones a little bigger in future production runs could make it easier for DIYers
• C18 and C19 solder pads are unfortunately lacquered over. I had to scrape the laquer off in order to solder the components in place. Same for CRZ jumpers. Maybe this can be corrected in next production runs
• Be patient, take your time and check, double check and check your work again – it’s a bit of a mind-numbing job and so easy to mount some components the wrong way round. I’ve had to de-solder and remount 1 or 2 components on the way, despite making sure I was putting them in the right way first time round! (or so I thought...)
• Here in the UK Mouser seems to be the best source for most components, but they don’t have everything. I sourced from a variety of places Farnell, HiFiCollective, ModulusAmplification and Toby Electronics covered everything I needed.
• I’m mounting the boards directly onto those big and beautiful (4U) HFi2000 heatsinks. I’ve drilled and tapped my own heat sink mounting holes using a small hand drill and good quality M3 middle tap & holder (i.e ~ £15! - watch out for some of the Chinese rubbish floating around out there). This task proved to be easy and simple – just make sure you use DIYAudios very useful universal mounting specification
That’s it for now – I eagerly await supply of the PSU boards to become available
– in the meantime I’m finishing off the amplifier boards, soft starts, speaker protection boards and also building a simple, programmable IR remote control receiver to manage power on/off for this baby.When building an amp, it's nominal impedance (4,6, or 8 ohm) is set right? So the honeybadger is for 8 ohm speakers, ideally, right? Are you able to build an amp where you can choose to send 4, 6, or 8 to your speakers?
When a amp says x watts at 8 ohms, and x watts at 4 ohms does the amp automatically adjust to what impedance the speaker is???
When a amp says x watts at 8 ohms, and x watts at 4 ohms does the amp automatically adjust to what impedance the speaker is???
Help!
Just powered up my HB amplifier boards for the first time this evening. Board #1 is just fine, but board #2 immediately sent the sacrificial +V 10R resistor up in a cloud of smoke (and R53 with it). Strange thing is all is fine if I connect only +50VC and 0V, but as soon as I connect -50V as well, poof goes the +V 10R sacrificial resistor (and connecting only -50V and 0V is also OK). I’ve checked and double checked the boards, components and their polarities and all is OK. A quick resistance test across 0V and -50V (and +50V and 0V) gives me about 600 ohms on each so there’s definitely no short to cause such a high current drain. It’s not the PSU because it works fine on the other board. I can only think I must have a duff output transistor somewhere. Any suggestions or thoughts, advice on how to proceed troubleshooting this would be most welcome....
Just powered up my HB amplifier boards for the first time this evening. Board #1 is just fine, but board #2 immediately sent the sacrificial +V 10R resistor up in a cloud of smoke (and R53 with it). Strange thing is all is fine if I connect only +50VC and 0V, but as soon as I connect -50V as well, poof goes the +V 10R sacrificial resistor (and connecting only -50V and 0V is also OK). I’ve checked and double checked the boards, components and their polarities and all is OK. A quick resistance test across 0V and -50V (and +50V and 0V) gives me about 600 ohms on each so there’s definitely no short to cause such a high current drain. It’s not the PSU because it works fine on the other board. I can only think I must have a duff output transistor somewhere. Any suggestions or thoughts
, advice on how to proceed troubleshooting this would be most welcome....
OK that was a good clue... I tracked it down to a tiny copper strand that I'd managed to solder across Q12 Collector - Emitter
could barely see it with a magnifying glass! hopefully that'll do the trick.
HiFi Rookie, I think you may be confusing transmission line theory with power distribution. In the former we are trying to minimise reflections by making the generator/amp source impedance equal to the load/speaker impedance.
Maybe somewhere along the way you read about the power transfer theorem, where the answer to the question, "How do I get the maximum power from a generator into a load? is"--By arranging the load impedance to equal the generator source impedance.
In audio, reflections and impedance matching are generally of no consequence. For reasons of electromagnetic damping we minimise the source impedance resulting in a voltage source. This is akin to the electricity supply to your house. Thus it does not much matter whether you have everything or nothing turned on, the voltage remains the same.
That is not quite the end of the story as we need to design our generator/amp to deliver current to some minimum value load while still having a constant output voltage. Having taken care of that lighter loads take care of themselves. Hope this helps get your mind around the subject.
Keith
question about CSS and LTP current
Well I’ve powered up both boards (only 1 at a time using a temporary, under capped PSU I knocked up – still not clear when the Universal PSU boards will be available from the DIY store), connected to my pre-amp and speakers and even with wiring lying in an untidy mess all I can say about the sound is “WOW!” This is shaping up to be good and I can’t wait to finish it off so I can run both channels properly (just need those PSU boards ..... )
Something which has confused me a bit is the CCS and LTP current and how best to set that up... both boards measure ~6.7V across R14 with R7 adjusted to 85R (the build guide recommend ~8.25V with R7 at 85R, which gives a current of 3.75mA – but I haven’t been able to achieve that). I left R7 at ~70R which measured ~7V across R14 - which I suppose should give about 3.2mA at the LTP? How critical is this setting – should I up the current more to the recommended 3.75mA (which by my estimates is going to mean around 50-60R on R7)?
BTW the heatsink on Q10-12 (KSA1381 & KSC3503) is running fairly cool to the touch after about 20min of high volume listening if that helps
Well I’ve powered up both boards (only 1 at a time using a temporary, under capped PSU I knocked up – still not clear when the Universal PSU boards will be available from the DIY store
), connected to my pre-amp and speakers and even with wiring lying in an untidy mess all I can say about the sound is “WOW!” This is shaping up to be good and I can’t wait to finish it off so I can run both channels properly (just need those PSU boards ..... )Something which has confused me a bit is the CCS and LTP current and how best to set that up... both boards measure ~6.7V across R14 with R7 adjusted to 85R (the build guide recommend ~8.25V with R7 at 85R, which gives a current of 3.75mA – but I haven’t been able to achieve that). I left R7 at ~70R which measured ~7V across R14 - which I suppose should give about 3.2mA at the LTP? How critical is this setting – should I up the current more to the recommended 3.75mA (which by my estimates is going to mean around 50-60R on R7)?
BTW the heatsink on Q10-12 (KSA1381 & KSC3503) is running fairly cool to the touch after about 20min of high volume listening if that helps