I went the hardware route so it could be stand-alone. Would not have to use a computer to get it working. But, thats an individual preference and cost issue.
I got a new THD instrument here and learned the second harmonic (H2) is really about the only harmonic to increase as load Z goes down to 30 Ohms. The other harmonics are so far down it doesnt matter. In other words, the effect is benign.
BTW - if this was used as a line amp, instead, - driving high Z load like the input of power amp or what ever - the HTD+N is around .00025%.... H2 is .00015% of that total.
Thx-RNMarsh
I got a new THD instrument here and learned the second harmonic (H2) is really about the only harmonic to increase as load Z goes down to 30 Ohms. The other harmonics are so far down it doesnt matter. In other words, the effect is benign.
BTW - if this was used as a line amp, instead, - driving high Z load like the input of power amp or what ever - the HTD+N is around .00025%.... H2 is .00015% of that total.
Thx-RNMarsh
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I went the hardware route so it could be stand-alone. Would not have to use a computer to get it working. But, thats an individual preference and cost issue.
I got a new THD instrument here and learned the second harmonic (H2) is really about the only harmonic to increase as load Z goes down to 30 Ohms. The other harmonics are so far down it doesnt matter. In other words, the effect is benign.
BTW - if this was used as a line amp, instead, - driving high Z load like the input of power amp or what ever - the HTD+N is around .00025%.... H2 is .00015% of that total.
Thx-RNMarsh
True on individual taste but I would prefer a hardware solution over having to buy and debug software.
Nice to throw in the specs when using it as a pre-amp. I am tempted to use it as a pre-amp as well!
For some of us amateurs, we sometimes miss the little details. I see the regs that I bought (LT1963a) only like to run up to 20V max at the input. I am so used to just snapping up 18V secondary transformers that I missed that little bit of info. I should have picked something a bit lower on the secondary voltage.
For some of us amateurs, we sometimes miss the little details. I see the regs that I bought (LT1963a) only like to run up to 20V max at the input. I am so used to just snapping up 18V secondary transformers that I missed that little bit of info. I should have picked something a bit lower on the secondary voltage.
You can use an LM317 or LM7815/MC7815 ahead of the LT1963A.
question about heat from the regulators
jackinnj -
We know that the output transistors need to have heatsinking. How about the LT regs you mentioned? How much heat did they give off? I bought the dpak smt versions off ebay for a great price. I want to just 'dead bug' them on a proto board but how hot do they get with the head amp?
jackinnj -
We know that the output transistors need to have heatsinking. How about the LT regs you mentioned? How much heat did they give off? I bought the dpak smt versions off ebay for a great price. I want to just 'dead bug' them on a proto board but how hot do they get with the head amp?
both of which I have showed here on this forum
Could you provide the link?
Hmmm, this is just a combination of two well known circuits, both of which I have showed here on this forum. The input is the buffer as shown by JLH, the second part is as I described in Mpp thread to tweak JLHs headphone amp. Does this designer frequent DIY audio ??
Anyway it will sound and measure very well indeed.
Could you provide the link?
here is the original JLH headphone amp circuit --- RNMarsh
??
I bought about 2 yrs ago a JLH headphone amp being promoted on this DIYAudio site.... it doesnt measure as well, either. What else can i say. I even paid about $450 for a finished product off a headphone only site and wasnt pleased with the results, either. Now that one also sits unused as more wasted money. :-( It was all IC based.... but couldnt drive low Z headphones well... even with a buffer IC after the opamp. The sound matters. Measurements matter. Seemingly small changes matter.
Thx-RNMarsh
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JLH amp IC based? the sold u a fake.
A real JLH circuit is in my do do list (after yours, yay!)
A real JLH circuit is in my do do list (after yours, yay!)
PCB's Pls
thanks
Hi Would be intrested in pcb and / or parts pls let me know when they become avaliable, even the pcbs would help.After the turn of the year I will put together batches of parts (including the matched transistors.)
In the interim, I'll put together a BOM with the device sizes.
thanks
would be intrested in the pcb and bits when they are avaliable pls pm meAfter the turn of the year I will put together batches of parts (including the matched transistors.)
In the interim, I'll put together a BOM with the device sizes.
JLH amp IC based? the sold u a fake.
A real JLH circuit is in my do do list (after yours, yay!)
I just looked at my comment - some of it didnt come thru.... the JLH was bought off this forum/dyiaudio headphones here. Not IC. Others tried were IC based. There are many to choose from. Some are copies of others work- like JLH. Some are improvements on others work. I am here only to help with my headphone amp... its dirivation is discussed in detail in Linear Audio publication.
In another forum here in dyiaudio I am working on measuring the thd and harmonics and trying to come up with a signal source and thd meter to measure the headphone amp. each time I get something better to test with, the number drops. My older Audio-Precision wasnt up to the task. I now use a ShibaSoku AD725D which can measure directly, to -135db re 1 volt. Then I can add FFT and notch filters to drop that further. Now I need a better signal source and modifying an HP339A as a better (lower distortion) source. All started because I couldnt get an accurate number for my own headphone amp design with the A-P. Its been expensive but fun, too.
Thx-Richard Marsh
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Update -
Working on the psu using LM317 as a pre-regulator per jackinnj's input.
Thanks to one of our DIY mod's I picked up a TEK 475 scope on ebay for $235 and it arrived in great shape. The itch gets more serious! hehehe
Working on the psu using LM317 as a pre-regulator per jackinnj's input.
Thanks to one of our DIY mod's I picked up a TEK 475 scope on ebay for $235 and it arrived in great shape. The itch gets more serious! hehehe
I've put together some kits of parts for the Marsh headphone amplifier -- you've got two choices: 1) Semiconductors and active components = $54;
2) Semiconductors = $27.50.
This will be sufficient for a pair of amplifiers -- one for each ear.
The JFETs are matched for Idss (that is you get a 2N5460 and 2N5457 which are matched for Idss +/- 0.1mA), bipolar output devices for hfe.
Yes, there is a markup. Mother Theresa is dead.
2) Semiconductors = $27.50.
This will be sufficient for a pair of amplifiers -- one for each ear.
The JFETs are matched for Idss (that is you get a 2N5460 and 2N5457 which are matched for Idss +/- 0.1mA), bipolar output devices for hfe.
An externally hosted image should be here but it was not working when we last tested it.
Yes, there is a markup. Mother Theresa is dead.
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