What are the benefits of using laterals in a buffer like he above. I have one set of boards wired up with IRF fets and was considering putting 2sk1058/sj162 in the other. I don't have test equipment so the only measurements i will have are my two ears and the space between, which seems expansive these days. I have read that they are more stable and don't necessarily require Rs. While i know this may help with noise, what does it do to linearity and distortion.
> I have read that they are more stable and don't necessarily require Rs.
Yes.
They need no degrading temperature compensations.
BUT ! ...................... AND ............. !
They are stable @ ~ 0.10 Amp rather than ~ 1.00 Amp (as IRF type parts)
> While i know this may help with noise, what does it do to linearity and distortion.
It helps because of the simplicity of being able to ignor temperature
(to a sensible extent)
Yes.
They need no degrading temperature compensations.
BUT ! ...................... AND ............. !
They are stable @ ~ 0.10 Amp rather than ~ 1.00 Amp (as IRF type parts)
> While i know this may help with noise, what does it do to linearity and distortion.
It helps because of the simplicity of being able to ignor temperature
(to a sensible extent)
Last edited:
Might as well try, right. Hope to try Fairchild parts as well. I want to wire my F4 boards with a switch between the FE and the buffer so that it can function as both F4 and BA output. I have a few questions though. In the F4, C3 and C4 serve as bootstrap caps for FE, but in BA output, these are grounded and bootstrap resistors are dropped. Will it affect the performance of the BA version if wired like F4 with bootstrap resistor and cap in place and wired to output. Also, in F4 there are two smaller electrolytics on FE but on BA there is 1 larger cap. Once again, will performance be affected if i use the two smaller caps. To use as standard F4, i need both, so should I just increase or leave alone?
I have been reading about driving lateral outputs and have found somethingt that i had a question on. Many folks use different gate resistors for the N and P channel parts as a way of trying to balance the different gate capacitances of the devices. Some even use smaller caps to accomplish the smae task. I have not seen Nelson do this on any of his push pull outputs and was wondering about the importance. Most of these suggestions come from the BJT Uber low THD chasers and I don't necessarily subscribe to the Massive OLG/Low THD school of though.
Looking at datasheet, is it optimal to try to bias the transistor into the linear region of the input capacitiance? Above 3V, looks very linear and would get me into a similar bias setting to standard F4. Am i right in how I am looking at this. Also, small Rs may be helpful, but i will try without. ANy comments welcomed.
Ussually the linear region of FET C does not even begin to start until about 20Vds 😀
I'm not sure but I think a mismatch of characteristics of N-P will give you 2nd Harmonics. Not so bad 😀
I'm not sure but I think a mismatch of characteristics of N-P will give you 2nd Harmonics. Not so bad 😀
check out datasheet and see what you think. 3Vgs @10Vds and up is about 2A and is in the linear C range.
Last edited:
I tried them in my crippled F4 and they have a sweet sound compared to the FQA......
Generg, you are busy. Sweet but sloppy, or just sweet. Will be matching this weekend. I have one crippled F4 ready, the other will get the newly matched Lateral. SO you have heard the FQA, what do you think?
Nelson or anybody, what role does the gm of a fet play when using it as a buffer like F4. Doesn't it mainly affect the output impedance
Nelson or anybody, what role does the gm of a fet play when using it as a buffer like F4. Doesn't it mainly affect the output impedance
Hi buzzforb,
I meant "sweet" because the singers were so engaged, or to say it more pathetique, like a mother singing to a child....
Do not hit me for the comparison......
In general I have no more intention to describe sounds, it is tooooooooo complicated to find the right words....
The FQA seem to me more precise not so dark, maybe high tones are a bit better.
I had to change a bit the bias network to get rid of the offset. It was to negative first.....
I did not match the laterals, I thought matching is only useful within the same polarity when you have three or four pairs........?
When I tried to cancel k2 I had this time no success a very small amount remained.
With the IRFs I could manage a considerable amount of lowering the distortion.....
Why...?
Interested to hear your experiences!
I meant "sweet" because the singers were so engaged, or to say it more pathetique, like a mother singing to a child....
Do not hit me for the comparison......
In general I have no more intention to describe sounds, it is tooooooooo complicated to find the right words....
The FQA seem to me more precise not so dark, maybe high tones are a bit better.
I had to change a bit the bias network to get rid of the offset. It was to negative first.....
I did not match the laterals, I thought matching is only useful within the same polarity when you have three or four pairs........?
When I tried to cancel k2 I had this time no success a very small amount remained.
With the IRFs I could manage a considerable amount of lowering the distortion.....
Why...?
Interested to hear your experiences!
I am using three pairs in the ouputs, so i will have to match. I know what you men about describing sound, no worries though, I don't know where you live.😀
Why the IRF has lower distortion is a mystery to me. The two main reasons I am trying the lateral version is because they can be used without Rs and there capacitance is much more linear than the IRF parts. I though this was a major contributor to distortion. Also, because they don't have as much gain, i thought they would be cleaner. Oh well. I like sweet anyway. THe Crippled F4/ BA output are going to be the end of major builds for me. From now on, I am going to focus on FE's for them. I like the idea of being able to easily switch and get different sound. I know i am ulitmately tied to the output to some degree, but who said that is a bad thing. It is just such a flexible amp. Did you try the lats I have or did you have other like 2sj201 and its sibling. I am going to post a BA-C schematic soon. Don't know if it works. I guess we will see this weekend. Hats off to your production level. I have too many kids to get things done quickly.
Why the IRF has lower distortion is a mystery to me. The two main reasons I am trying the lateral version is because they can be used without Rs and there capacitance is much more linear than the IRF parts. I though this was a major contributor to distortion. Also, because they don't have as much gain, i thought they would be cleaner. Oh well. I like sweet anyway. THe Crippled F4/ BA output are going to be the end of major builds for me. From now on, I am going to focus on FE's for them. I like the idea of being able to easily switch and get different sound. I know i am ulitmately tied to the output to some degree, but who said that is a bad thing. It is just such a flexible amp. Did you try the lats I have or did you have other like 2sj201 and its sibling. I am going to post a BA-C schematic soon. Don't know if it works. I guess we will see this weekend. Hats off to your production level. I have too many kids to get things done quickly.
So you know the "sweet" sound when your wife is singing to the kids.....🙂
May be a little misunderstanding, the IRFs had the higher k2 level before starting to get it down...
The laterals had from beginning on a lower k2 level and I could not minimize the level by paralleling source resistors on one side like Nelson did with F5.
I took 2SJ201 and 2SK1530.
I will be using sj162/sk1058 and will try without Rs at first. Your lats have more gain and i think this is another parameter that affects buffer performance. When i get them fired up, I will post pics and desription of why operating parameters were chosen.
[offtopic]
Niemals! Seit "panoramic sound" bin ich der Stammkunde für deine Vergleiche ! 😀
[/offtopic]
- Status
- Not open for further replies.