Yeah Juanitox - at last...
Hi!
My SIT has been running (somewhat hot) for 1 month approximately now. Got a little stuffed inside - so I`m planning to move some big caps and tighten things up. That way I can try some other solutions - the 100000 uf bypasscaps or other things people have suggested.
But for now I will only take the output cap on the B1 out and try the sound then. Today I got a new speakercable(QED) - and the lower frequencies got magnified greatly and to the bone.
But soon off to sea - and in july off 2 weeks to Spain for a vacation - so my hobby will be put a little aside till autumn.
Best to you and the rest of us Pass-followers!
Olav
Hi!
My SIT has been running (somewhat hot) for 1 month approximately now. Got a little stuffed inside - so I`m planning to move some big caps and tighten things up. That way I can try some other solutions - the 100000 uf bypasscaps or other things people have suggested.
But for now I will only take the output cap on the B1 out and try the sound then. Today I got a new speakercable(QED) - and the lower frequencies got magnified greatly and to the bone.
But soon off to sea - and in july off 2 weeks to Spain for a vacation - so my hobby will be put a little aside till autumn.
Best to you and the rest of us Pass-followers!
Olav
thanks all, i have a 0,22uf VCap Cutft on the Amp input with a Choke ( 5mohm ac impedance at 1khz) some caps are good but i prefer to keep it small for sound and save money
great olav that you have finally built your SITamp
I can't see why you need the choke on the input unless you have RF present from somewhere else ?
Hi all!
Report from my set-up: Today I have removed the output cap(10uf) on my B1. So the chain is more and more stripped= 2 transistors on the B1 - 1 input 1 uf.
On th 2SK82SIT there are 1 transistor and 1 input cap(10uf) and 1 output cap (10000 uf w/ 10 uf bypass poly).
Less is more - and the low freq is so..... much better.
And the sound is a big step forward - like Ryan Adams is in the room with his Ashes and Fire. And there are no noise from anything in my chain. You can hear a week humming from the transformers close by(0,5m).
Now I only need a better potmeter on the B1 - suggestion anyone???
Best
Olav
Report from my set-up: Today I have removed the output cap(10uf) on my B1. So the chain is more and more stripped= 2 transistors on the B1 - 1 input 1 uf.
On th 2SK82SIT there are 1 transistor and 1 input cap(10uf) and 1 output cap (10000 uf w/ 10 uf bypass poly).
Less is more - and the low freq is so..... much better.
And the sound is a big step forward - like Ryan Adams is in the room with his Ashes and Fire. And there are no noise from anything in my chain. You can hear a week humming from the transformers close by(0,5m).
Now I only need a better potmeter on the B1 - suggestion anyone???
Best
Olav
a grid choke as gate leak resistor , have a low DC resistance ( about 1,5kohm) what is good for the sit bias and a high AC impedance to reduce the input Cap of my input from 10uf to 0,22uf ..
if you don't afraid about accuracy , a Goldpoint or Dact are good , TKD plastique POT are good too but less transparent , PEC carbon is good to add some meat on the bone but can be scratchy if there is any DC and not very accurate on low level. i like to make use shunt type with one caddock or nude vishay series ( 27K) and any of these pots as shunt resistor ( 20K)
cheers olav..
Not my B1 - humming... some from SIT
KatieandDad - sorry for misinformation.
My B1 is very silent(a quiet powersupply from an old notebook) but there a some weak humming from the two big 400watts transformer in each of the mono 2SK82SIT (LÀmp) - and that is as expected. But you have to keep your ear closeby to hear it!
Best
Olav
KatieandDad - sorry for misinformation.
My B1 is very silent(a quiet powersupply from an old notebook) but there a some weak humming from the two big 400watts transformer in each of the mono 2SK82SIT (LÀmp) - and that is as expected. But you have to keep your ear closeby to hear it!
Best
Olav
10uf caps are there for DC blocking.the value is not that critical,but 1uf would be too low for that.
Regards,
Sachin
Thanks Atilla this what I was hoping to see "The 10uF value has an 'I can plug this into anything' margin"
10uF will work with 500k and 100k and 20k and at a push 10k. i.e. as said above it works with just about anything.
The "problem" you have unearthed is that the DC blocking cap in a Source component can never know what equipment it is going to be connected to later in life.
If you intend spending good money on a very high quality audio cap for DC blocking then fit that at the input to the Power Amplifier. Do this for every Power Amplifier you have. Then you can short across all the cheap or sized too small DC blocking capacitors in all your Source gear.
A workable alternative is to have dual in/outs on all your gear.
Power amp has a DC coupled input in parallel with the AC input. You use whichever input suits the Source you are connecting. And almost as important you can use just ONE DC blocking cap rather than two DC blocking caps in series.
eg.
Source is fitted with 1uF output cap. Power amp is fitted with 2u2F input cap and has Rin=22k.
The effect of connecting these together is that the amp F-3dB is moved from 3.3Hz to 10.5Hz
All your Sources have a dual output. one is DC coupled and the other is AC coupled.
This way you connect in the "best" coupling cap you have just by swapping around the interconnect.
The "problem" you have unearthed is that the DC blocking cap in a Source component can never know what equipment it is going to be connected to later in life.
If you intend spending good money on a very high quality audio cap for DC blocking then fit that at the input to the Power Amplifier. Do this for every Power Amplifier you have. Then you can short across all the cheap or sized too small DC blocking capacitors in all your Source gear.
A workable alternative is to have dual in/outs on all your gear.
Power amp has a DC coupled input in parallel with the AC input. You use whichever input suits the Source you are connecting. And almost as important you can use just ONE DC blocking cap rather than two DC blocking caps in series.
eg.
Source is fitted with 1uF output cap. Power amp is fitted with 2u2F input cap and has Rin=22k.
The effect of connecting these together is that the amp F-3dB is moved from 3.3Hz to 10.5Hz
All your Sources have a dual output. one is DC coupled and the other is AC coupled.
This way you connect in the "best" coupling cap you have just by swapping around the interconnect.
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Thanks Andrew.
Yes I would like to spend money on these caps in the B1 as it will be the only caps in the chain. The B1 will be driving a F5 with no caps as you know. The input impedance is 101k // with the 221K on B1 output. F-3dB will be 2.3Hz if I use 1uF on output.
There is a huge! difference in price from a 1uF to a 10uF. So would rather spend as much as I can on a very good 1uF than an average 10uF.
Yes I would like to spend money on these caps in the B1 as it will be the only caps in the chain. The B1 will be driving a F5 with no caps as you know. The input impedance is 101k // with the 221K on B1 output. F-3dB will be 2.3Hz if I use 1uF on output.
There is a huge! difference in price from a 1uF to a 10uF. So would rather spend as much as I can on a very good 1uF than an average 10uF.
once the B1 is connected to the F5, the 221k becomes superfluous.
The 221k is there to ground any leakage from the cap when the B1 is not connected.
You can increase that output grounding resistor to any value >500k, I tend to use 2M2.
The same value at the input to the power amp.
These two superfluous resistors, once the system is connected, add only 1M1 in parallel to Rin and can just about be ignored.
I prefer F-3dB <2Hz. It seems to suit my ears and speakers and room.
2M2//2M2//100K = 91k7 and with 1uF gives RC ~ 92ms
You can then add a teflon or similar dielectric in parallel to the 1uF. You may like the result. There are a few Members who recommend such. Maybe a value from 10nF to 100nF would be about right.
But I say again.
Once you know your power amp it is better to locate the DC blocking cap in the power amp, not in the source.
The 221k is there to ground any leakage from the cap when the B1 is not connected.
You can increase that output grounding resistor to any value >500k, I tend to use 2M2.
The same value at the input to the power amp.
These two superfluous resistors, once the system is connected, add only 1M1 in parallel to Rin and can just about be ignored.
I prefer F-3dB <2Hz. It seems to suit my ears and speakers and room.
2M2//2M2//100K = 91k7 and with 1uF gives RC ~ 92ms
You can then add a teflon or similar dielectric in parallel to the 1uF. You may like the result. There are a few Members who recommend such. Maybe a value from 10nF to 100nF would be about right.
But I say again.
Once you know your power amp it is better to locate the DC blocking cap in the power amp, not in the source.
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normally the Rin of the receiver swamps the value of the grounding resistor. That makes the grounding resistor virtually ignorable once the system is connected.
however where Rin = 101k and the two grounding resistors are 221k (one at the source output and the same at the receiver input) then the effect of these grounding resistors cannot be ignored. 221k//221k ~ 110K and that is comparable to Rin. This silly selection of component values reduces F-3dB by ~ one octave.
Design the system, not just individual components in the system.
Note for 100K for my Rin example I suggested 2M2 for the two grounding resistors.
I can call them superfluous because I chose values such that when connected they have virtually no effect on F-3dB. (do you need the sums to see the F-3dB effect?)
Think about the system !
however where Rin = 101k and the two grounding resistors are 221k (one at the source output and the same at the receiver input) then the effect of these grounding resistors cannot be ignored. 221k//221k ~ 110K and that is comparable to Rin. This silly selection of component values reduces F-3dB by ~ one octave.
Design the system, not just individual components in the system.
Note for 100K for my Rin example I suggested 2M2 for the two grounding resistors.
I can call them superfluous because I chose values such that when connected they have virtually no effect on F-3dB. (do you need the sums to see the F-3dB effect?)
Think about the system !
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