So my Kester Solder Simulator did not know what to do with a SPICE model so I tried LTSPICE. The roll of solder just sat there and did not even start the simulation let alone converge to a solution. With LTSPICE I managed to get a reasonable looking very first simulation for the Solo HPA (attached) using the component values installed on the board I bought.
By the way if anyone wants to learn how to use LTSPICE there is a very good thread here:
Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
It is pretty easy except for a few odd quirks. Like changing a transistor model to a library model. (Such as one of Bob Cordell's BJT models.) For example, you don't open the NPN's dialog box and edit the transistor type. Instead you right click on the schematic text to type in the model name for an included library transistor model.
Now for fun I can change the schematic and see what difference other output stages make. (At least in simulation.) If I were to try a WHAMMY type output in simulation would a PC817 be ok for the opto? (I ask since that is what I have in my parts box.) I would like to try other designs to find a nicer looking harmonic profile with lower 3rd and fewer (high) harmonics at high levels.
By the way if anyone wants to learn how to use LTSPICE there is a very good thread here:
Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
It is pretty easy except for a few odd quirks. Like changing a transistor model to a library model. (Such as one of Bob Cordell's BJT models.) For example, you don't open the NPN's dialog box and edit the transistor type. Instead you right click on the schematic text to type in the model name for an included library transistor model.
Now for fun I can change the schematic and see what difference other output stages make. (At least in simulation.) If I were to try a WHAMMY type output in simulation would a PC817 be ok for the opto? (I ask since that is what I have in my parts box.) I would like to try other designs to find a nicer looking harmonic profile with lower 3rd and fewer (high) harmonics at high levels.
Attachments
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After certainly the longest gestation period in diyAudio history, the WHAMMY has a chassis ready to ship.
There is also an updated parts kit, which will be shipping in the near future.
Many thanks to everyone who was involved in making this happen.
Both the parts kits and the chassis are now on the shelf in the US warehouse.
Chassis: The WHAMMY Chassis is ready to purchase now, and can ship immediately.
Parts Kit: The WHAMMY completion kit requires a minor parts addition before we can start shipping. I'm speaking to our warehouse to see if we can start taking pre-orders now, before the fix is done on the parts kits. If this is possible, we'll be advertising a shipping date of November 31, but it's likely the fix will be done before then and we can ship sooner.
A friendly reminder that we do not ship partial orders - orders only ship once everything in the order is ready to ship.
You can view the whole WHAMMY offering in the new WHAMMY section of the store.
The complete kit page will get tidied up once I have information from our warehouse.
There is not yet a build guide using the new chassis, you will have to get by with Jim's excellent one using a Hammond chassis, and some help from your friends here should you have any questions.
There is also an updated parts kit, which will be shipping in the near future.
Many thanks to everyone who was involved in making this happen.
Both the parts kits and the chassis are now on the shelf in the US warehouse.
Chassis: The WHAMMY Chassis is ready to purchase now, and can ship immediately.
Parts Kit: The WHAMMY completion kit requires a minor parts addition before we can start shipping. I'm speaking to our warehouse to see if we can start taking pre-orders now, before the fix is done on the parts kits. If this is possible, we'll be advertising a shipping date of November 31, but it's likely the fix will be done before then and we can ship sooner.
A friendly reminder that we do not ship partial orders - orders only ship once everything in the order is ready to ship.
You can view the whole WHAMMY offering in the new WHAMMY section of the store.
The complete kit page will get tidied up once I have information from our warehouse.
There is not yet a build guide using the new chassis, you will have to get by with Jim's excellent one using a Hammond chassis, and some help from your friends here should you have any questions.
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WHAMMY Simulation
Could someone familiar with the WHAMMY please take a look at my attached first cut simulation? Does it look right? THD looks absurdly low so I am wondering if I did something wrong.
Does anyone have measurements of the WHAMMY that they are willing to share?
Could someone familiar with the WHAMMY please take a look at my attached first cut simulation? Does it look right? THD looks absurdly low so I am wondering if I did something wrong.
Does anyone have measurements of the WHAMMY that they are willing to share?
Attachments
Apologies for the crosspost
To date, WHAMMY has been performing superbly! Gorgeous sounds and definition. It's never had a problem driving either my HD6XX or my newly-acquired Hifiman HE560v4.
A few days ago, I came to my desk and heard a squealing sound. While searching for its source, I realized it was coming from my headphones. I turned everything off, disconnected it, and cracked the case. As soon as I took the last screw out, the all-to-familiar smell of hot electronics filled the air.
Upon inspection, I saw that one of the output transistor supporting resistors has gotten warm. And two of the power supply resistors for the input opamp were quite roasty. And the opamp was literally toasted. Likely what caused the resistors to heat up. The resistors measured correctly, so I replaced the opamp with a different kind and the music returned, which is great news. However, after a bit of time, the resistors began to heat up and smoke, so presume that they were damaged to the point of needing to be replaced even though they read okay.
So pondering root cause here. Options:
So I'll be ordering new resistors at a minimum. The opamp power supply caps appear fine. I have other opamps to use. Output transistors appear to be unfazed. I'm happy to look at other places in the system for degraded components if you have any suggestions.
To date, WHAMMY has been performing superbly! Gorgeous sounds and definition. It's never had a problem driving either my HD6XX or my newly-acquired Hifiman HE560v4.
A few days ago, I came to my desk and heard a squealing sound. While searching for its source, I realized it was coming from my headphones. I turned everything off, disconnected it, and cracked the case. As soon as I took the last screw out, the all-to-familiar smell of hot electronics filled the air.
Upon inspection, I saw that one of the output transistor supporting resistors has gotten warm. And two of the power supply resistors for the input opamp were quite roasty. And the opamp was literally toasted. Likely what caused the resistors to heat up. The resistors measured correctly, so I replaced the opamp with a different kind and the music returned, which is great news. However, after a bit of time, the resistors began to heat up and smoke, so presume that they were damaged to the point of needing to be replaced even though they read okay.
So pondering root cause here. Options:
- opamp was degraded and it was only a matter of time before it failed
- Hot swapping DACs and somehow provided an unfavorable input condition that shorted the opamp, heated its power supply resistors, driving the output stage into saturation causing the squeal
- aliens
So I'll be ordering new resistors at a minimum. The opamp power supply caps appear fine. I have other opamps to use. Output transistors appear to be unfazed. I'm happy to look at other places in the system for degraded components if you have any suggestions.
Attachments
Hasn't gone on sale yet, but will in a few hours (pre-order, shipping within a few weeks but worst case end of November).