What was shown has nothing to do with the HDAM.
It was just meant to be an example that the HDAM is not the holy grail.
But you can take this as reference and just take out the power devices.
the Headphone amplifier
Cheers,
Patrick
It was just meant to be an example that the HDAM is not the holy grail.
But you can take this as reference and just take out the power devices.
the Headphone amplifier
Cheers,
Patrick
Hi Patrick,
Yes, I got that. Kevin is working on something similar already that he has built in a different format.
-Chris
Yes, I got that. Kevin is working on something similar already that he has built in a different format.
-Chris
This is Ciuffolli's Pioneer Super Linear as a line amp.
All through hole, no unobtanium.
The 5k trimmer is used to set bias.
But do simulate first before building.
Real excellent performance as a headphone amp.
The Pioneer Super Linear Circuit
DC servo not necessary, in my experience.
Patrick
.
All through hole, no unobtanium.
The 5k trimmer is used to set bias.
But do simulate first before building.
Real excellent performance as a headphone amp.
The Pioneer Super Linear Circuit
DC servo not necessary, in my experience.
Patrick
.
Attachments
Hi Chris,
I’m good with the direction your taking 😉
Actually, I’m starting to prefer projects with smd.
(Not interested in a headphone amp though)
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Per Chris' comment any objections to 1206, 0805, SOT-23, SOT-223 packages? LSK389 is available in SOIC-8 which is what I have been using in my discrete op-amps.
I was considering using the Cordell Dh-220c front end design and doing it in smt. It is a premium using lsk489 & lsj689 but it has the advantages of being a symetrical push-pull design. Having a dc servo means very low offset and DC coupling, no caps at least on the o/p. Then there is a opa1656 which is your new base line to determine is a discrete design necessary at all these days for low levels. What gets me is why a pre-amp with gain is needed at all. What source levels are you dealing with? Do you only need a buffer or gain too? I was thinking all I need these days is some source switching and a attenuator for each channel in my power amp.
If you are new to smt use 1206, 0805
If you are new to smt use 1206, 0805
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Hi Rick,
What's wrong with output capacitors? I think they are necessary as I have had preamps whose DC servo op amps did fail. That will cost the owner a woofer (and has). I good polypropylene coupling cap isn't there sonically speaking. I think it is irresponsible not to use one.
Some gain is always handy for various phono cartridges and a few sources I find on the bench. If you don't need gain - great, but this preamp didn't seem to have very much excessive gain at ll.
Besides, how else can you crank things up to 11? 🙂
-Chris
What's wrong with output capacitors? I think they are necessary as I have had preamps whose DC servo op amps did fail. That will cost the owner a woofer (and has). I good polypropylene coupling cap isn't there sonically speaking. I think it is irresponsible not to use one.
Some gain is always handy for various phono cartridges and a few sources I find on the bench. If you don't need gain - great, but this preamp didn't seem to have very much excessive gain at ll.
Besides, how else can you crank things up to 11? 🙂
-Chris
I do not listen to records anymore but understand it is needed for phono and tape machines, the old 150mV standard pre level.
Some people do not like capacitors, for coupling. I am fine with using certain ones. I do not claim that I can hear a diff but i have had feed back from customers saying they can and like the idea that they can eliminated it in the dc-220c design.
It goes along the same route as wanting no ecap in the feedback path in a power amp. The evil ecap as it is referred too. Sansui was one of the first to remove it and have a dc offset adj
I guess if you want a dc o/p pre you might need a mute relay and dc detector too, let’s make it more complicated 🙂
Some people do not like capacitors, for coupling. I am fine with using certain ones. I do not claim that I can hear a diff but i have had feed back from customers saying they can and like the idea that they can eliminated it in the dc-220c design.
It goes along the same route as wanting no ecap in the feedback path in a power amp. The evil ecap as it is referred too. Sansui was one of the first to remove it and have a dc offset adj
I guess if you want a dc o/p pre you might need a mute relay and dc detector too, let’s make it more complicated 🙂
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Hi Rick,
In any power amplifier, lack of an input capacitor is criminal neglect! I can't think of a more dangerous and irresponsible situation except to allow the equipment to run all the time on top of that. I can't tell you how many times I have had DC out of a preamp running amplifiers to some DC level. Krell eventually installed an input monitor to look for DC, but no one else does.
Once again, uneducated people in the audio field are making stupid decisions. I resist requests to short out input caps and will turn away work I feel is dangerous. This is dangerous.
-Chris
In any power amplifier, lack of an input capacitor is criminal neglect! I can't think of a more dangerous and irresponsible situation except to allow the equipment to run all the time on top of that. I can't tell you how many times I have had DC out of a preamp running amplifiers to some DC level. Krell eventually installed an input monitor to look for DC, but no one else does.
Once again, uneducated people in the audio field are making stupid decisions. I resist requests to short out input caps and will turn away work I feel is dangerous. This is dangerous.
-Chris
Rick,
> It is a premium using lsk489 & lsj689 but it has the advantages of being a symetrical push-pull design.....
If you are prepared to pay for those, you should really build a Blowtorch like circuit :
John Curl's Blowtorch preamplifier part II
Not only push-pull, but fully differential, like e.g. an OPA1632.
You can then use it as SE to BAL, BAL to SE, BAL to BAL, etc.
With or without gain.
I shall not post the full schematics here.
I am one of those many highly-uneducated criminals who do not use input and output caps.
😉
Cheers,
Patrick
> It is a premium using lsk489 & lsj689 but it has the advantages of being a symetrical push-pull design.....
If you are prepared to pay for those, you should really build a Blowtorch like circuit :
John Curl's Blowtorch preamplifier part II
Not only push-pull, but fully differential, like e.g. an OPA1632.
You can then use it as SE to BAL, BAL to SE, BAL to BAL, etc.
With or without gain.
I shall not post the full schematics here.
I am one of those many highly-uneducated criminals who do not use input and output caps.
😉
Cheers,
Patrick
Attachments
Hi Patrick,
So beyond the cost of a good capacitor, why don't you use them?
-Chris
I guess you haven't had one go DC yet. In service I tend to see all failures over the years - and the results of those failures.
So beyond the cost of a good capacitor, why don't you use them?
-Chris
Each to his own.
I guess with an IQ of 145, a Ph.D. in Engineering and well over 100 international patents,
I am probably not the most stupid or uneducated.
😉
Cheers,
Patrick
I guess with an IQ of 145, a Ph.D. in Engineering and well over 100 international patents,
I am probably not the most stupid or uneducated.
😉
Cheers,
Patrick
Hi Patrick,
No offense intended, but Universities are often called "puzzle factories" because often highly educated and institutionalized folks lack common sense.
My IQ is also very high, but I am a practical person who was university educated in Electronics (communications). I have zero patents, but am responsible for countless manufacturing modifications (ECOs) which isn't bad for an independent not part of those organizations. My life is all about "what is" and what does in fact happen.
So, while I can respect your preference, you failed to answer my question. I'll ask again. I'm not going to debate your answer, I just wonder if you actually thought about it or its a snap decision made without much consideration.
So beyond the cost of a good capacitor, why don't you use them?
By the way, measurements don't show any change in output spectrum, no added distortion and I can't hear it, try as I might. I have tested this many times.
-Chris
No offense intended, but Universities are often called "puzzle factories" because often highly educated and institutionalized folks lack common sense.
My IQ is also very high, but I am a practical person who was university educated in Electronics (communications). I have zero patents, but am responsible for countless manufacturing modifications (ECOs) which isn't bad for an independent not part of those organizations. My life is all about "what is" and what does in fact happen.
So, while I can respect your preference, you failed to answer my question. I'll ask again. I'm not going to debate your answer, I just wonder if you actually thought about it or its a snap decision made without much consideration.
So beyond the cost of a good capacitor, why don't you use them?
By the way, measurements don't show any change in output spectrum, no added distortion and I can't hear it, try as I might. I have tested this many times.
-Chris
Someone else pointed this out originally so no credit to me, but the 47K resistors are not the correct value, the tail current is supposed to be 6 - 7mA so each of those resistors should see roughly 3 - 3.5mA from the fets and some additional current from the cascodes. The voltage at that node is set by the two diodes and the pnp cascode vbe. The voltage across those resistors and pot cannot be more 0.7V. I suspect those two resistors actually should be 47R. Total current for the fet and folded cascode would be in the vicinity of 7mA per side.