Could you point me to the original Blameless amp thread? I can't find it.
Also, i've read somewhere that it's all about trial and error with this amp till it sounds good. I can't remember where.. What did they mean?
One more thing. The Apex amps seem pretty nice. How do they perform? I mean many said they are very good, tho' i don't know about which they were talking about... I suppose it was the B500.
Also, i've read somewhere that it's all about trial and error with this amp till it sounds good. I can't remember where.. What did they mean?
One more thing. The Apex amps seem pretty nice. How do they perform? I mean many said they are very good, tho' i don't know about which they were talking about... I suppose it was the B500.
Hi Guys
I don't know if there was such a thread here - there would likely have been.
From Doug's own site, you can see the fig.33 below. To make it suitable for more power, just add more output BJTs with current sharing emitter Rs.
You can also check out Rod Elliot's project-68 500W amp (sound.westhost.com). He is skimpy on supply filtering but has boards for most of his projects.
Have fun
Kevin O'Connor
I don't know if there was such a thread here - there would likely have been.
From Doug's own site, you can see the fig.33 below. To make it suitable for more power, just add more output BJTs with current sharing emitter Rs.
You can also check out Rod Elliot's project-68 500W amp (sound.westhost.com). He is skimpy on supply filtering but has boards for most of his projects.
Have fun
Kevin O'Connor
Attachments
Some other old but hopefull not dated amps. Slone is not among us but I believe his amps may deserve some recognition.
Audio Kits
Audio Kits
I didn't get a chance to swap any transistors to day but I did get a chance to reset the bias. When I was done, I ran some tests using the sinewave generator and scope. I discovered that the generator will put out more voltage on a Square wave so I tested with with that. I still couldn't get the amp to clip. Here are some pics of the test.
Left channel, generator on left and op on right
left channel, generator on bottom, output on top
Right channel, generator on left, output on right.
Right channel, generator on bottom, output on top.
Left channel, generator on left and op on right
left channel, generator on bottom, output on top
Right channel, generator on left, output on right.
Right channel, generator on bottom, output on top.
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The result are pretty nice. Thank you for sharing!
Andrewlebon, I won't build the h900 because it's too powerfull and it's class g. Tho the B500 is actually the h900 without the step up circuitry so that's the one I'm thinking of making.
Damon Hill, thank you for the site, although that's the one I found too. I can't manage to find his schematics and projects, only the articles.
Struth, can you please tell ne what transistors are those? I can't find the page where you downloaded it from.
I'll check out thr honey badger thread again although I have checked it before and didn't like something.
Also, about Slone's amps, the mosfet one is too expensive to build and the bipolar one is too low power. I'd have to run more pairs and higher rails, but running higher rails will pretty much burn some other transistors. So some small transistors have to be changed and I think some resistors should be recalculated, so it' s too much.
Overall, I'm pretty much going for the B500 or the Blameless amp depending which output transistors are available where I live.
Thank you all for your support!
Andrewlebon, I won't build the h900 because it's too powerfull and it's class g. Tho the B500 is actually the h900 without the step up circuitry so that's the one I'm thinking of making.
Damon Hill, thank you for the site, although that's the one I found too. I can't manage to find his schematics and projects, only the articles.
Struth, can you please tell ne what transistors are those? I can't find the page where you downloaded it from.
I'll check out thr honey badger thread again although I have checked it before and didn't like something.
Also, about Slone's amps, the mosfet one is too expensive to build and the bipolar one is too low power. I'd have to run more pairs and higher rails, but running higher rails will pretty much burn some other transistors. So some small transistors have to be changed and I think some resistors should be recalculated, so it' s too much.
Overall, I'm pretty much going for the B500 or the Blameless amp depending which output transistors are available where I live.
Thank you all for your support!
Post82.
The Re = 0r1 will be OK for most output devices.
If you raise the supply to +-50Vdc then some devices may require a higher value of Re to maintain THERMAL Stability.
If you raise the supply to +-65Vdc then most devices will require a higher value of Re to maintain THERMAL Stability.
Expect Re minimum to be around 0r22 for +-65Vdc and don't be surprised if Re>=0r33 is required.
If you have a 3pair output stage using MJ21193/4 with Re=0r33, then that is roughly equivalent to a single pair with Re=0r11
3pair MJ gives a 1500W output stage. That can easily produce a reliable 250W when the transformer, PSU & heatsink are correct.
The Re = 0r1 will be OK for most output devices.
If you raise the supply to +-50Vdc then some devices may require a higher value of Re to maintain THERMAL Stability.
If you raise the supply to +-65Vdc then most devices will require a higher value of Re to maintain THERMAL Stability.
Expect Re minimum to be around 0r22 for +-65Vdc and don't be surprised if Re>=0r33 is required.
If you have a 3pair output stage using MJ21193/4 with Re=0r33, then that is roughly equivalent to a single pair with Re=0r11
3pair MJ gives a 1500W output stage. That can easily produce a reliable 250W when the transformer, PSU & heatsink are correct.
Still4given, i checked out the honey badger thread again and found the same thing that stopped me from building it before.
On page 92 of the presentation and design thread, cod3gen asked if he could use the amp at +-85v (which is how much i have and need) in 4 ohms (i actually need only 8 but not the current capability is the problem.)
Stormrider answered. I shall quote:
"For +/- 85Vdc you should have six pairs of plastic output devices for driving four ohm speakers. +/-60Vdc really is the max for the Honey Badger."
"It would take a complete redesign. The Honey Badger has an EF2 output stage. Anything bigger should have an EF3. Look into the 6 pair Leach or Leach Double-Barrel."
Now i realized that the honey badger amp uses the EF2 output stage as does the blameless amp too, i think. Wouldn't that make the blameless amp also unsuitable for my needs?
On page 92 of the presentation and design thread, cod3gen asked if he could use the amp at +-85v (which is how much i have and need) in 4 ohms (i actually need only 8 but not the current capability is the problem.)
Stormrider answered. I shall quote:
"For +/- 85Vdc you should have six pairs of plastic output devices for driving four ohm speakers. +/-60Vdc really is the max for the Honey Badger."
"It would take a complete redesign. The Honey Badger has an EF2 output stage. Anything bigger should have an EF3. Look into the 6 pair Leach or Leach Double-Barrel."
Now i realized that the honey badger amp uses the EF2 output stage as does the blameless amp too, i think. Wouldn't that make the blameless amp also unsuitable for my needs?
Hi Guys
"Blameless" is Doug Self's term for a power amp that does not alter the sound, ie it has no defects and is thus 'blameless' in the system. The Blameless amp can be made with EF2, EF3, or CFP with single or parallel output devices. The CFP is preferred for linearity and allows lower idle currents - 15mA instead of 120mA for EF.
The honey-badger is one form of Blameless with some extra bits added that do not enhance performance.
Most guys who complain that the Blameless amp is dull or boring or lacks mids or trreble are just fooling themselves. They are used to hearing distortion and maybe for the first time are hearing a much less distorted signal sent to their speakers. As I've said before, you have to train your ear to recognise this type of clean sound for what it is. This does not mean that accurate sound is an acquired taste, rather that most people have never had the opportunity.
For the power levels they claim for the HB - 150W-8R, 240W-4R - they need more than two pairs of output device. The fact power does not double into 4R means they are using a small PT and allowing quite a bit of supply sag to save the output devices.
If you want to use this as your party amp, it would be better to add more BJTs, and better to have an EF-triple to assure proper low-impedance drive at low-THD. Do not skimp on heat sinking.
Doug used low-cost widely available BJTs in his published designs. They work well.
For your +/-90V supply:
Have at least 10-15mF per rail per channel.
Use MPSA42 (npn) and MPSA92 (pnp) for everything up to the VAS. They are fine for the predriver in the EF-triple
Use MJE15034 and MJE15035 as drivers.
Use MJL1302A and MJL3281A, or MJL21193 and MJL21194 output devices. Four pairs minimum.
Have fun
Kevin O'Connor
"Blameless" is Doug Self's term for a power amp that does not alter the sound, ie it has no defects and is thus 'blameless' in the system. The Blameless amp can be made with EF2, EF3, or CFP with single or parallel output devices. The CFP is preferred for linearity and allows lower idle currents - 15mA instead of 120mA for EF.
The honey-badger is one form of Blameless with some extra bits added that do not enhance performance.
Most guys who complain that the Blameless amp is dull or boring or lacks mids or trreble are just fooling themselves. They are used to hearing distortion and maybe for the first time are hearing a much less distorted signal sent to their speakers. As I've said before, you have to train your ear to recognise this type of clean sound for what it is. This does not mean that accurate sound is an acquired taste, rather that most people have never had the opportunity.
For the power levels they claim for the HB - 150W-8R, 240W-4R - they need more than two pairs of output device. The fact power does not double into 4R means they are using a small PT and allowing quite a bit of supply sag to save the output devices.
If you want to use this as your party amp, it would be better to add more BJTs, and better to have an EF-triple to assure proper low-impedance drive at low-THD. Do not skimp on heat sinking.
Doug used low-cost widely available BJTs in his published designs. They work well.
For your +/-90V supply:
Have at least 10-15mF per rail per channel.
Use MPSA42 (npn) and MPSA92 (pnp) for everything up to the VAS. They are fine for the predriver in the EF-triple
Use MJE15034 and MJE15035 as drivers.
Use MJL1302A and MJL3281A, or MJL21193 and MJL21194 output devices. Four pairs minimum.
Have fun
Kevin O'Connor
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Hi Kevin,
I must say you have piqued my interest in the Blameless. I have done some searching but have not found any good data for building one. If you know where to look I would appreciate a link.
Brlmat,
I skimmed through the B500 thread. Does it have audiophile qualities? It is advertized as a PA amp. Your statement earlier about the Leach requiring closely matched transistors, the only ones that need matching are Q1-4 and they are inexpensive enough to buy several and get matches easily. After listening to thsi amp fora few days now it is quickly becoming one of my favorites. I can't wait to get it into a cabinet so I can use it more.
I must say you have piqued my interest in the Blameless. I have done some searching but have not found any good data for building one. If you know where to look I would appreciate a link.
Brlmat,
I skimmed through the B500 thread. Does it have audiophile qualities? It is advertized as a PA amp. Your statement earlier about the Leach requiring closely matched transistors, the only ones that need matching are Q1-4 and they are inexpensive enough to buy several and get matches easily. After listening to thsi amp fora few days now it is quickly becoming one of my favorites. I can't wait to get it into a cabinet so I can use it more.
Kevin,
That is one of the truest statements I have ever read on DIYAudio. Period. I'm not necessarily referring to the Blameless amp (cause I want to build it!), but about 'training your ear'. As a teenager in the 60's I couldn't afford anything better that a 20wpc Lafayette amp, a Rat Shack turntable, and some inexpensive small bookshelf speakers. But since that was all I had, I thought it sounded pretty sweet. I had no other reference. I had a mono Lafayette tape recorder too and that must have rolled everything off at 16Khz or less! Super flat and dead sounding by even the mildest of today's audio standards!
I now recogonize that since the advent of the CD, hi dynamic range, and high SNR amplifiers that are common place today, even mid-fi today sounds miles ahead of what I listened back then. It's amazing to me today, that it doesn't take much micro electronics, monolithic chips to produce some pretty amazing sound. Maybe not audiophile grade, but very very good. Fast forward 50 yrs... My ears aren't as golden as they once were, but I can still tell good sound when I hear it. I'm not after the holy grail of audio, just a little higher-hifi!
Rick
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Hi Guys
Terry, I would say that back in the 1970s solid-state amp design essentially split down two paths, for the most part based on single-ended and push-pull drive. Here, I'm referring to the VAS - not SE and PP as it applies to tube amps.
The SE drive camp used either single BJT inputs, or diff with diff winning out for the most part for the bulk of eventual production. In the SE drive camp, the "fact" that the current through the VAS should be essentially constant meant the VAS worked into either a bootstrap or a constant current source. Refinements such as CCS for the diff amp, current mirror load for the diff, cascoding here or there were just variations on the basic skeleton.
The push-pull camp split into two subgroups: The first were along Otala's line, of a diff followed by a diff loaded by a current mirror to push-pull drive the output stages. Later forms had three diffs cascaded for huge openloop gain. The other subgroup took advantage of the new symmetric BJTs to create fully complimentary symmetry circuits, like the Leach.
In all three formats, the output stages went from totem poles, to quasi-comp, to full symmetry - most of the latter as EFs with one or two as CFPs. Also, all three paths were trying to maximise gain in different ways to achieve the same end of low THD. Whether that "maximum" was moderate or extreme was up to the designer.
The notion that the VAS current should be constant is in fact a fallacy; truly an economy-driven result that was misinterpreted at the very least, and possibly misrepresented. The proof is in the real fact that a couple of the very best performing amp brands use push-pull drive with no ill effects - actually, with highly beneficial effect. One of those "rules of thumb" that is plain wrong and obsolete.
Doug Self's "Blameless" follows the SE drive path and represents a collection of the better refinements that provides reliably good performance.
I prefer full symmetry but stay away from jfet front ends. Jfets are notoriously difficult to match and these days are extremely difficult to find. This problem extends to power mosfets. There used to be quite a few Japanese offerings but these have dwindled and most that still exist are slated for discontinuance. That leaves the IRFs, which are not designed as compliments. Besides, despite a few specs that are very enticing with mosfets, BJTs can run circles around them in a real amp.
Rick, there was a distinct down-turn in amp quality when things went "theatre". I picked up a cheap Yamaha thingy to use as an interim amp while I built something. 0.09% THD but lots of DSP stuff to make your home sound like outer space, or something... I don't use any of its features and it gets muddy if you push it, so I never push it. I actually got it to cut a crossover into it and use four of its channels to biamp with, but the lousy specs have kept me from bothering with that. Back in the '80s, a similar product would have been DC-100kHz with many zeroes of THD.
Have fun
Kevin O'Connor
Terry, I would say that back in the 1970s solid-state amp design essentially split down two paths, for the most part based on single-ended and push-pull drive. Here, I'm referring to the VAS - not SE and PP as it applies to tube amps.
The SE drive camp used either single BJT inputs, or diff with diff winning out for the most part for the bulk of eventual production. In the SE drive camp, the "fact" that the current through the VAS should be essentially constant meant the VAS worked into either a bootstrap or a constant current source. Refinements such as CCS for the diff amp, current mirror load for the diff, cascoding here or there were just variations on the basic skeleton.
The push-pull camp split into two subgroups: The first were along Otala's line, of a diff followed by a diff loaded by a current mirror to push-pull drive the output stages. Later forms had three diffs cascaded for huge openloop gain. The other subgroup took advantage of the new symmetric BJTs to create fully complimentary symmetry circuits, like the Leach.
In all three formats, the output stages went from totem poles, to quasi-comp, to full symmetry - most of the latter as EFs with one or two as CFPs. Also, all three paths were trying to maximise gain in different ways to achieve the same end of low THD. Whether that "maximum" was moderate or extreme was up to the designer.
The notion that the VAS current should be constant is in fact a fallacy; truly an economy-driven result that was misinterpreted at the very least, and possibly misrepresented. The proof is in the real fact that a couple of the very best performing amp brands use push-pull drive with no ill effects - actually, with highly beneficial effect. One of those "rules of thumb" that is plain wrong and obsolete.
Doug Self's "Blameless" follows the SE drive path and represents a collection of the better refinements that provides reliably good performance.
I prefer full symmetry but stay away from jfet front ends. Jfets are notoriously difficult to match and these days are extremely difficult to find. This problem extends to power mosfets. There used to be quite a few Japanese offerings but these have dwindled and most that still exist are slated for discontinuance. That leaves the IRFs, which are not designed as compliments. Besides, despite a few specs that are very enticing with mosfets, BJTs can run circles around them in a real amp.
Rick, there was a distinct down-turn in amp quality when things went "theatre". I picked up a cheap Yamaha thingy to use as an interim amp while I built something. 0.09% THD but lots of DSP stuff to make your home sound like outer space, or something... I don't use any of its features and it gets muddy if you push it, so I never push it. I actually got it to cut a crossover into it and use four of its channels to biamp with, but the lousy specs have kept me from bothering with that. Back in the '80s, a similar product would have been DC-100kHz with many zeroes of THD.
Have fun
Kevin O'Connor
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Blameless or Leach PCBs?
I got half way through another post here last night and fat-fingered the keyboard and wham - lost it all and couldn't recover any of it. I hate when that happens! Speaking of 'best' amps.....
Besides the HoneyBadger implementation of the Blameless amp (available at the DIY store), what other commercial offerings are available for professionally produced, 2-sided PCBs for the Blameless, Leach, and/or other, similarly spec'd DIY-based amps? I've always preferred to start with a nice PCB first, find the BOM in kit form(if available), but I haven't seen too many offerings for the Leach or other amps, that represent high-grade audio performance.
I'm leaning more and more to building the DS' Blameless amp, but at the moment have too many other commitments to keep me busy for the next 30-90 days. I just want to make sure I explore all the other options that may exist out there. Thoughts?
BTW, I built the DS 2012 Pre last year and could't be happier with its sound. It's by far the nicest piece of gear I have and thus, often reveals the short-comings of my lesser mid-fi equipment. Several have taken Doug to task for the design - from everything to using the wrong OP amps to only focusing on specs, but Since I don't have a higher reference, I'm thrilled with the way it sounds with my gear - and none if it is hi-end. So, maybe I'm not even seeing the 2012 Pre's full potential - yet.
I got half way through another post here last night and fat-fingered the keyboard and wham - lost it all and couldn't recover any of it.
I hate when that happens! Speaking of 'best' amps.....Besides the HoneyBadger implementation of the Blameless amp (available at the DIY store), what other commercial offerings are available for professionally produced, 2-sided PCBs for the Blameless, Leach, and/or other, similarly spec'd DIY-based amps? I've always preferred to start with a nice PCB first, find the BOM in kit form(if available), but I haven't seen too many offerings for the Leach or other amps, that represent high-grade audio performance.
I'm leaning more and more to building the DS' Blameless amp, but at the moment have too many other commitments to keep me busy for the next 30-90 days. I just want to make sure I explore all the other options that may exist out there. Thoughts?
BTW, I built the DS 2012 Pre last year and could't be happier with its sound. It's by far the nicest piece of gear I have and thus, often reveals the short-comings of my lesser mid-fi equipment. Several have taken Doug to task for the design - from everything to using the wrong OP amps to only focusing on specs, but Since I don't have a higher reference, I'm thrilled with the way it sounds with my gear - and none if it is hi-end. So, maybe I'm not even seeing the 2012 Pre's full potential - yet.
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Sometimes I wonder if it´s worth the effort to seek for the (plausible) optimal alternative or go for something that likely is good enough?
I have built some amps during the years and for the my first amp built on a PCB I did the layout by hand, no PC:s at that time. But knowing the work involved starting from scratch there is of course the risk of ending up with an amp that have a sound that doesn´t satisfies you. You may lower the risk taken by buying something that has a resell value like an amplifier module maybe?
As mentioned by others there is some guesswork involved even if you go for something you believe is good enough. (On the other hand it would be boring if everything was in fact predictable). For my part I would consider if buying a modules from e.g. Aussie Amplifiers och maybe this one (link) is my starting point.
Ground Sound
I have built some amps during the years and for the my first amp built on a PCB I did the layout by hand, no PC:s at that time. But knowing the work involved starting from scratch there is of course the risk of ending up with an amp that have a sound that doesn´t satisfies you. You may lower the risk taken by buying something that has a resell value like an amplifier module maybe?
As mentioned by others there is some guesswork involved even if you go for something you believe is good enough. (On the other hand it would be boring if everything was in fact predictable). For my part I would consider if buying a modules from e.g. Aussie Amplifiers och maybe this one (link) is my starting point.
Ground Sound
All I'm asking for is that there are a couple of notable amps on DIY and the 2 or 3 that have multiple threads seem to be the Blameless, Leach, and Pass. So, by deduction one would think these designs have something reasonably favorable to offer in terms of good, quality sonic characteristics. Yes? Maybe not suitable for everyone, but they do seem to have a credible following here.
I really have no desire (nor the skill, or equipment) to design from scratch an amplifier, much less do the PCB layout. There are design engineers that get paid to do that. Especially, when it comes to the critical layout of class D amps. I'm not sure your everyday, DIY amp builder wantabe has the skill set to do that properly. Hence my desire for a PCB, that is based on a solid, fundamental, tried and true design that if constructed properly will provide very, very good results. So, my gravitation towards the Blameless, Leach or Pass. But I'm open to suggestions, I'm just not aware of other class A/AB designs, but I'm sure there must be others.
I have had very good success using pre-assembled modules, but I don't shy away from component level assembly either. I cut my building skills teeth years ago on Heathkits, and computer kits in the late 70's and early 80's. I have found a couple of Chinese vendors on eBay that have a variety of offerings at the kit, and pre-assembled level that I've been very happy with. That's what I've focused my attention on since picking backup my audio DIY interest a couple years ago. I've also built numerous amps based on monolithic chips. Some class AB and several class D and T.
Now I want to move the bar a little higher and step up the level of performance and tackle a bigger amp project. The Honey Badger looks like a suitable candidate, so I may explore that one more.
It's all fun.
Rick
Ps. Thanks for the link to the Ground Sound. Will explore it too.
I really have no desire (nor the skill, or equipment) to design from scratch an amplifier, much less do the PCB layout. There are design engineers that get paid to do that. Especially, when it comes to the critical layout of class D amps. I'm not sure your everyday, DIY amp builder wantabe has the skill set to do that properly. Hence my desire for a PCB, that is based on a solid, fundamental, tried and true design that if constructed properly will provide very, very good results. So, my gravitation towards the Blameless, Leach or Pass. But I'm open to suggestions, I'm just not aware of other class A/AB designs, but I'm sure there must be others.
I have had very good success using pre-assembled modules, but I don't shy away from component level assembly either. I cut my building skills teeth years ago on Heathkits, and computer kits in the late 70's and early 80's. I have found a couple of Chinese vendors on eBay that have a variety of offerings at the kit, and pre-assembled level that I've been very happy with. That's what I've focused my attention on since picking backup my audio DIY interest a couple years ago. I've also built numerous amps based on monolithic chips. Some class AB and several class D and T.
Now I want to move the bar a little higher and step up the level of performance and tackle a bigger amp project. The Honey Badger looks like a suitable candidate, so I may explore that one more.
It's all fun.
Rick
Ps. Thanks for the link to the Ground Sound. Will explore it too.
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The amps I have built using comercially made PCB's are Leach Low TIM, (Jan's boards), two KSA 50's, one with TO-3's and one with Plastic transistors, a Symasym5 and an Aleph x.
All of these were from Group Buys except the Aleph which was a gift. My favorite sounding is the Symasym and it was the cheapest to build. They are all really nice sounding except the Aleph and I am sure it is because I made changes to the BOM.
Now that I am back, the Honey Badger, DX amps and APEX amps have all caught my interest. Fortunately I have a few projects to finish so I can take some time reading before jumping into another amp build right away. Besides, I still have a pair of Symasym boards and a pair of KSA 100 MKII, PH Watts boards I could build.
Blessings, Terry
All of these were from Group Buys except the Aleph which was a gift. My favorite sounding is the Symasym and it was the cheapest to build. They are all really nice sounding except the Aleph and I am sure it is because I made changes to the BOM.
Now that I am back, the Honey Badger, DX amps and APEX amps have all caught my interest. Fortunately I have a few projects to finish so I can take some time reading before jumping into another amp build right away. Besides, I still have a pair of Symasym boards and a pair of KSA 100 MKII, PH Watts boards I could build.
Blessings, Terry
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Terry,
Aren't the KSA 100 Krell? I thought those amps were only commercial/retail and not available for DIY. Do they offer just the PCB? I was reading another thread (it's easy to get them confused at times.
) where they were discussing the KSA 100 I believe, but didn't get the connection between retail Krell and the KSA 100. Are they clones of what's in a Krell? IIRC some young guy in the Netherlands was building one, and it was humongous and looked to weight about 100 pounds! Not that that would deter me . Can you enlighten? I might be a bit advanced and priced higher than my needs right now. - Status
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