While also some building information comes with the boards, I created a wiki-entry
The high octane phono preamp - diyAudio
where everybody is welcome to add information on whatever you find important or practical to build this little amp!
I will also add information as it becomes available!
The high octane phono preamp - diyAudio
where everybody is welcome to add information on whatever you find important or practical to build this little amp!
I will also add information as it becomes available!
Yes the webmaster did an update yesterday and now response is very slow! My apologies, we're working to get it resolved, should be OK in a few hours.
Jan
BTW Notice that the two output resistors are NOT on the PCB! You need to solder them directly to the output connectors. If you forget to do it you're in trouble, i.e. you build yourself a pair of oscillators...
Jan
Jan
... and, there's an LED as reference in the supply reg. I thought to be smart and put that LED on the fronpanel via some 5 inch of wiring. Which nicely picked up some hum which made me wonder why the fack there's hum on the supply ... 😱
Jan
Jan
No apologies necessary, Jan. a) I'm retired, and have all the time in the world, and, b) it was $1.13 for something of great value. Just wanted others to be aware that, however slow, the process did work.
Thanks Patrick, it appeared to be an attack against the servers that also host my website....
All well again,
Jan
I couldn't connect to the Linear Audio server to download the article this morning but it worked fine this afternoon.
Today i received the pcb, thank you Hannes!
As no loading resistors are installed i was thinking to install only 2 cap loading and on the other 2 positions to install two resistors.
Happy soldering !
As no loading resistors are installed i was thinking to install only 2 cap loading and on the other 2 positions to install two resistors.
Happy soldering !
Found in my drawer some KSC 1845 with medium hfe 320 and some BC550 with hfe around 620. Wich one is prefered hfe-wise ?
I sent for a set of these as well. At that price, not much at stake...like you said, pretty good ratings...fingers crossed!
Russellc
Hi everybody,
currently almost all boards are gone and I'm still contacting people that pm'ed me on October, 7!
I'm really very sorry for everybody that mailed me later as there won't be a board left for you. Of course I will respond to every pm even if only to bring the bad news.
I never expected such an interest and feel honored by the pm bombardment!
I will try to get a cheap quote for a 2nd run of boards. Let's see if I can get up with something.
BTW, the regulator LED is pretty critical as it directly sits on the opamp input 😉
@atupi: I glad to hear you got the board already! I would use the higher hfe BC part.
The high octane is ideally suited as MM-phono preamp with its low capacitance bjt-inputs and 46dB gain. Of course you can also use it with medium output MCs and use load resistors. Or even combine it with a nice step-up transformer...
currently almost all boards are gone and I'm still contacting people that pm'ed me on October, 7!
I'm really very sorry for everybody that mailed me later as there won't be a board left for you. Of course I will respond to every pm even if only to bring the bad news.
I never expected such an interest and feel honored by the pm bombardment!
I will try to get a cheap quote for a 2nd run of boards. Let's see if I can get up with something.
BTW, the regulator LED is pretty critical as it directly sits on the opamp input 😉
@atupi: I glad to hear you got the board already! I would use the higher hfe BC part.
The high octane is ideally suited as MM-phono preamp with its low capacitance bjt-inputs and 46dB gain. Of course you can also use it with medium output MCs and use load resistors. Or even combine it with a nice step-up transformer...
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I will get these as well. Will compare printouts. Thanks for the heads up on the resistors that are not on the board.
Russellc
Most of MM cartridges wants to "see" 47k on the preamp input. In this case R1 is 100k, Is a good move to replace R1 with the recommended value of cartridge manufacturer?
Regarding the use of the Hight Octane pre with a low output MC cartridge plus step-up transformer, I wonder what would be the optimal capacitance load. I suppose it depends on the specific model of cartridge/step up trafo, but manufacturers usually don't give reccomended values, because MC carts are supposedly much more tolerant to capacitance loads. Nevertheless .. what do you think, guys ?
Please note that R1 is parallel to the bipolar transistor Q1, which reduces input impedance strongly. A BJT is very different from a jfet, for which your calculation would be fine.
With Q1 installed the input impedance is about 47kR as intended.
This is my solution for CP2. Cut that trace and use the elcap - terminal to connect to ground.
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An externally hosted image should be here but it was not working when we last tested it.
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În the paper sent with pcb Hannes told us Cp2 has a pcb error regarding ground pin.
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