If some one goes ahead with Bob Cordell’s update as a kit or finished board i’d buy 12 boards/kits and pay up front to get it going. Yes they won’t be cheap - you get what you pay for, and Bob should get a royalty.
Hi ticknpop,
I should have the DH-220C pcb's this week. I have asked BobC if he would be so kind as to review it. Bob said he would do so, but it will have to wait, as he is too busy with the book release at this point. So, I wait patiently. Bob did ask for me to wait for him to review/test the design before I release it.
I did order up a few pcb's, since I had another order to do and could combine shipping. I can work one up in the mean time.
The pcb itself will be relatively cheap, the BOM I have loaded up in Mouser and that is about ~$60CDN($40USD), plus the jfets which are about $10USD each.
I usually do not sell finished/tested pcb's, it is just too time consuming and non-economical but I am open to set aside time for the rich and famous. People who have more $ than they know what to do with 🙂
Will sell the pcb's (probably on eBay since it is the easiest for me) and provide a link to a Mouser shopping cart. May consider selling the jfets with the pcb. One option is for me to solder on only the jfets in the sot-23-6 package, if it is an issue and it is used instead of the TO-71. There is a dual footprint on the pcb for these devices.
Since the design is public information, there is no requirement for royalties, but I will discuss this with Bob. People are free to send $ to Bob, I am sure he won't mind 🙂
So hang in there for now on DH-200C, but it is coming soon.
Rick
I should have the DH-220C pcb's this week. I have asked BobC if he would be so kind as to review it. Bob said he would do so, but it will have to wait, as he is too busy with the book release at this point. So, I wait patiently. Bob did ask for me to wait for him to review/test the design before I release it.
I did order up a few pcb's, since I had another order to do and could combine shipping. I can work one up in the mean time.
The pcb itself will be relatively cheap, the BOM I have loaded up in Mouser and that is about ~$60CDN($40USD), plus the jfets which are about $10USD each.
I usually do not sell finished/tested pcb's, it is just too time consuming and non-economical but I am open to set aside time for the rich and famous. People who have more $ than they know what to do with 🙂
Will sell the pcb's (probably on eBay since it is the easiest for me) and provide a link to a Mouser shopping cart. May consider selling the jfets with the pcb. One option is for me to solder on only the jfets in the sot-23-6 package, if it is an issue and it is used instead of the TO-71. There is a dual footprint on the pcb for these devices.
Since the design is public information, there is no requirement for royalties, but I will discuss this with Bob. People are free to send $ to Bob, I am sure he won't mind 🙂
So hang in there for now on DH-200C, but it is coming soon.
Rick
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Whatever suits you for your time, your work is greatly appreciated as is Bob’s.
Are you going to the Toronto Diy meet on Sunday?
Are you going to the Toronto Diy meet on Sunday?
Thanks,
I was going to attend but I forgot that I have a scope test to be done on Monday morning, so I need to prep. Just bad timing for me. I should be able to attend the summer bbq if it happens, maybe we can have a working unit for that event.
Since I know you are interested, I will keep you informed as to our progress and let you know when we are ready.
Cheers
Rick
I was going to attend but I forgot that I have a scope test to be done on Monday morning, so I need to prep. Just bad timing for me. I should be able to attend the summer bbq if it happens, maybe we can have a working unit for that event.
Since I know you are interested, I will keep you informed as to our progress and let you know when we are ready.
Cheers
Rick
Hi,
It is not a whole lot of $ in parts, I have the pcb's made up, but it will have to wait, since I have other work to finish up first, I need the jfets & Bob Cordell did ask me to wait for him to review and test out the design first.
Thanks for your generous offer to help and contribute.
Rick
It is not a whole lot of $ in parts, I have the pcb's made up, but it will have to wait, since I have other work to finish up first, I need the jfets & Bob Cordell did ask me to wait for him to review and test out the design first.
Thanks for your generous offer to help and contribute.
Rick
Rick, you are doing a great job here, and it is exciting that there is interest in the DH220C. I'm looking forward to reviewing the design and ultimately seeing how the unit works.
I'm sort of in the critical path right now getting the book published, reviewing final proofs, but the end is well in sight. The publication date is still slated for May 31. I just noticed yesterday that they have it available for pre-order on the Routledge site for 20% off. I've also updated my web page to reflect the second edition.
Cheers,
Bob
Bob:
I'm glad you can finally see light at the end of the tunnel and that it's not the headlights of a train!
🙂
We're cheering you on to the finish line.
Thanks to folks for the Routledge site link - definitely worth making that change!
mlloyd1
I'm glad you can finally see light at the end of the tunnel and that it's not the headlights of a train!
🙂
We're cheering you on to the finish line.
Thanks to folks for the Routledge site link - definitely worth making that change!
mlloyd1
Hmm. I just threw away a functioning XL280. If I could have slapped in a new loaded design/pcb... Maybe even a CFA design ... Oh well. Too late now.
-RNM
-RNM
Hi Ozark HiFi Doctor,
Firstly,
Back to being a member after giving everyone an official warning ...
Ever have to do an insurance report on an incident involving other people (technical expert). I have a number of times for everything from lightning damage, AC mains faults and fire caused by equipment failure. Amplifiers generally do not burn. But, speakers often do, and extremely well. I've written several reports that point the finger at idiot technicians that remove protection, or mornic manufacturers that don't include them to begin with. Which are you (by your own admission earlier)?
This is actually a serious thing that you can't rightfully ignore.
I will agree that some protection measures can negatively affect the sound quality. However, the energy source (amplifier) must always have a load disconnect feature in the event of a fault condition. This should sound familiar to you as the same rules apply in industry and consumer goods. I have seen amplifiers without a DC blocking capacitors burn out speakers (woofer and crossover) when the previous equipment goes DC, also without any safeguards. The last one was an older Krell system, and it did burn the woofers.
I sincerely hope you learn something, and perhaps seek out more experience for yourself. You seem very insulated from the real world and don't even get that your efforts can have serious consequences for people who trust you. IF I were a judge that found you negligent, I would order that you proceed with a recall for products you have removed protection on and either reinstate the factory protection, or some other suitable form of protection. Just try to be a responsible technician for a change.
-Chris
Firstly,
I didn't say that, nothing even close. What you just did is a serious infraction, so smarten up. Since I am active in this thread, I won't moderate. When I do in other threads, the person that does that gets anything from points to bin time. My warning will probably suffice this time.
Back to being a member after giving everyone an official warning ...
I do, quite often in fact. I have an established track record of calling out folks who ignore safety and expose their customers to potentially dangerous situations.
Ever have to do an insurance report on an incident involving other people (technical expert). I have a number of times for everything from lightning damage, AC mains faults and fire caused by equipment failure. Amplifiers generally do not burn. But, speakers often do, and extremely well. I've written several reports that point the finger at idiot technicians that remove protection, or mornic manufacturers that don't include them to begin with. Which are you (by your own admission earlier)?
This is actually a serious thing that you can't rightfully ignore.
That is an ignorant comment. Check my posting history if you feel qualified to level that statement at anyone, including me. I've been doing this for over 40 years and have had classical training as well as training seminars and doing a great deal of work in this field. Given what you feel is acceptable I can only assume you have only seen on the job training in a fast and very loose environment. No real technician will do what you have admitted to doing.
I will agree that some protection measures can negatively affect the sound quality. However, the energy source (amplifier) must always have a load disconnect feature in the event of a fault condition. This should sound familiar to you as the same rules apply in industry and consumer goods. I have seen amplifiers without a DC blocking capacitors burn out speakers (woofer and crossover) when the previous equipment goes DC, also without any safeguards. The last one was an older Krell system, and it did burn the woofers.
I sincerely hope you learn something, and perhaps seek out more experience for yourself. You seem very insulated from the real world and don't even get that your efforts can have serious consequences for people who trust you. IF I were a judge that found you negligent, I would order that you proceed with a recall for products you have removed protection on and either reinstate the factory protection, or some other suitable form of protection. Just try to be a responsible technician for a change.
-Chris
Bob, just wondering why was output stage error correction iomitted in the redesigned DH 220? That would have lowered the overall distortion significantly.
Is that a future project?😉
Is that a future project?😉
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While it would have reduced distortion significantly, I didn't bother putting error correction in the DH220C, partly because it would have been an even bigger departure from the original DH 220 and also because the extra circuitry probably would not have fit. The DH220C is already pretty tight. Also, I have never applied Hawksford error correction (HEC) to a lateral MOSFET design. The fact that lateral MOSFETs are slower than verticals (as a result of higher effective series gate resistance) also can impact the compensation and effectiveness of HEC.
Cheers,
Bob
Cheers,
Bob
Hi Bob,
If the customer wants to have something completely different, then large departures from the original design are okay.
-Chris
Bob, those are well considered reasons for not changing the amp into something completely different. The question then becomes when are changes an upgrade or an entirely new amplifier? Something we should keep in the back of our minds.
If the customer wants to have something completely different, then large departures from the original design are okay.
-Chris
Agreed. The main point is that the DH220 is a great platform for upgrades, significant changes, or even completely new lateral MOSFET amplifiers.
Cheers,
Bob
Bob,
Most lateral fet amps I’ve built had .1 uf polypropylene cap as a bypass for the bias spreader, yet your using a 100 uf electrolytic , what benefit to the larger value when the output stage impedance is so high that 0.1 uf seems to have been enough?.
What do the 220k resistors in the bias spreader do ?
Most lateral fet amps I’ve built had .1 uf polypropylene cap as a bypass for the bias spreader, yet your using a 100 uf electrolytic , what benefit to the larger value when the output stage impedance is so high that 0.1 uf seems to have been enough?.
What do the 220k resistors in the bias spreader do ?
I am cheating here, since I have been fortunate enough to review a couple of chapters in the new book where this is explained in detail.
Restoration and optimizing of classics (cars or amps)
A critical point, ..seems misunderstood.., is that there is an initiative to extract the greatest performance out of classic Hitachi MOSFETS (for me) more than retaining any particular circuit topology, stock parts with numerous associated limits. With respects, it is not so much about an homage to original design or the designers.
A Chip Foose one off, vintage restoration of a classic car, lets say Mustang, or even a Roush super build... the car IS STILL A CLASSIC MUSTANG, with vastly superior performance, not available in the day, for the market price and with current technology. Adding a turbo to a six figure Lamborghini [while extreme] raises the performance considerably, as the badge says... it is still a Lamborghini in every sense of the word.
With so many different pathways and hi-ways available to each of us... Not every one wants to or is able to follow the same path... having critical limits in place.
A critical point, ..seems misunderstood.., is that there is an initiative to extract the greatest performance out of classic Hitachi MOSFETS (for me) more than retaining any particular circuit topology, stock parts with numerous associated limits. With respects, it is not so much about an homage to original design or the designers.
A Chip Foose one off, vintage restoration of a classic car, lets say Mustang, or even a Roush super build... the car IS STILL A CLASSIC MUSTANG, with vastly superior performance, not available in the day, for the market price and with current technology. Adding a turbo to a six figure Lamborghini [while extreme] raises the performance considerably, as the badge says... it is still a Lamborghini in every sense of the word.
With so many different pathways and hi-ways available to each of us... Not every one wants to or is able to follow the same path... having critical limits in place.
Mod away as you desire but if you are messing with the high voltage AC and you create a safety/shock/electrocution hazard, then you become liable, you should correct and take responsibility for your actions. Safety is always first.
to quote Chris
to quote Chris
I just worked on a couple of Yamaha P-2200 amplifiers, there is no such device used in this design. There are many designs that do not have a speaker/load disconnect feature. Not like Yamaha stated that if the amp fails/rails it will potentially fry your speakers. Does Yamaha get sued for frying speakers?
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