Some other Source Follower Configurations

Hi Salas
I checked the calculations again with a calculator, and there is a mistake.
There is something wrong with excel. Excel is saying 4.95, and the calculator is saying 7.95
What ever you do don't try and build a space shuttle (or anything else for that matter) using excel.

I will go through and check the other calculations with my calculator, and update the results.
 
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To avoid confusion I will upload the results again.
There are definitely no mistakes that i can find.
Andrew might be kind enough to check the calculations.
 

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Hi Andrew,

Based on my subjective experience that most low impedance headphones tend to create a better sensation of bottom register presence and mid bass fullness when the drive is right,
I have also noticed the same thing playing bass through speakers of various impedance.
4Ohm sounds really good, 16 Ohm sounds absolutely rubbish. I don't know why, maybe you are right.
I personally theorised that bass notes are much higher in amplitude than most people suspect and to generate the same power into a 16Ohm load compared to a 4Ohm load you might be voltage clipping the amp.
Mind you even at quiet levels they (ie 16 Ohm speakers) sound rubbish, so it is very unlikely the amp will be voltage clipping at those levels.

I suspect you are right.
 
I have also noticed the same thing playing bass through speakers of various impedance.
4Ohm sounds really good, 16 Ohm sounds absolutely rubbish. I don't know why, maybe you are right...................

I suspect you are right.
I too used the loudspeaker analogy since I don't have sufficient experience of headphone amp and headphones themselves.

I came to exactly the opposite conclusion.
 
Yes, intuitively I agree with you Andrew, and I have to say I have not played through many 16 Ohm speakers, mainly beacuse they are very rare (most are 4Ohm and 8Ohm), but the ones I have played through have all sounded crap.
It could just be that the speakers were crap regardless of impedance, but to me it is interesting that Salas has observed/experienced the same thing.

Obviously to get good results with low impedance speakers the amp should be designed from the the start to handle such loads.

I have not passed judgment on this yet, it is just what I have experienced so far.
 
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I never talked about loudspeakers and straight Ohmic relations. I talked about possible advantages in small light transducers like those in cans regarding holding Force Factor high when utilizing extra current VS high impedance cans where it will be either more MMS by extra length of wire or non practical magnet size increase so to hold same BL, or just more resistive wire and losing BL.
 
hello guys i d like to know a couple things regarding this amp before i order parts.

how close must the lu1014 be matched? i know i can adjust the dc offset with the trimpot but is there any limit i should not cross? i m just wondering how many parts i should purchase in order to get the right matching. also what is the idss matching limit for 2sj103? 8ma +/-....?

by the way i m aiming for the balanced version:)
 
LU104 match :

You can only buy matched pairs or matched quads (at the same price) anyway as far as I know.

2SJ103 :

+/-2.5% if you want to plug & play. A bit more if you know how to trim.

Version :

Suggest you build the standard version without 2SJ103 first, to understand how it works and to get a feel of the sound, before you implement the TCS, and only then the balanced version.


Patrick
 
hello guys i d like to know a couple things regarding this amp before i order parts.

how close must the lu1014 be matched? i know i can adjust the dc offset with the trimpot but is there any limit i should not cross? i m just wondering how many parts i should purchase in order to get the right matching. also what is the idss matching limit for 2sj103? 8ma +/-....?

by the way i m aiming for the balanced version:)

Hi,

From your message it seems you're building the version with Taylor; mine is the version without, so no trimpot in my case. I bought "matched" pairs of LU1014D from Deep Surplus, and got DC offset of around 5mv on one channel and 6mV on the other, which I thought was just fine without further tweaking. (I also matched the mosfets with some care). I may just have been lucky, of course, and YMMV, but that was my experience.

Cheers

Nigel
 
i think i will be building the plain one first to get a feel of it just as EUVL suggested.

is the price fromm deepsurplus per jfet or per pair? wondering what is the accuracy of the matching because i saw on ebay 50 pieces unmatched for sale for 59$ shipped, which could be nice if no close match is required and if you want some extra.

dont know though what difference in the offset it can make and if it can be easily remedied by changing resistors without affecting too much performance.

by the way it was said earlier in this thread that mosfet matching didnt havew any impact on offset, IIRC.