Bosoz

[ralf]

Where to place the volumecontrol ?

Has somone made experiences with placing the volumecontrol in Bosoz?

I ask me, if i should place it in the output?
Advantage: no ssssss hearable in the speaker, when the volume is down.

Or should it be better to be placeed in the input of Bosoz.



I will only use one pot (DACT) for volume controling, at the other places ( input or output) i will put one resistor, only (to save money)

Which solution sounds better?


Ralf

 

[yasalam]

Hi Ralf,

As far as I know, the smallest value of DACT pot is 10K, so it is probably you better put it on input of Bozoz.

Yamin

 

[ralf]

why

why to the input?

can you explain me? Affects an volume control to the output the sound quality?

You should know: my speakers have a sensitivity at about 92db and when i put the volume control to the input of the bosoz the tweeters make a hearable "ssssssss".

How can i avoid this?

Please help me, cause a "ssssssss" has nothing to do with high end Quality.

Or should i build a different preamplifier? -but which one which converts unbalanced to balanced mode?
That would be a mess, cause the combination SOZ/BOSOZ sounds outstanding good.

Regards

Ralf

 

[mefinnis]

Actually, I think Nelson will suggest you put it in the output.

Ideally, the recommendation goes like this - adjust the input pot so the FETs are being driven adequately (output voltage swing 1-2V), then use the output pot as the volume contol.

Now, since you only want to use 1 pot (which I can understand entirely !!), I suggest you connect it initially in the input and adjust to a reasonable output level given your source (note, you will need to repeat this if you change sources). Measure the value and substitute fixed metal film resistors to match the circuit gain to your input source. Then place your DACT in the output, sit back and enjoy the music 😉

cheers, mark

 

[mefinnis]

Addendum: Please note that when I say insert a metal film resistor, I actually mean 2 resistors as a voltage divider, this being equivalent to the pot ....... just in case I wasn't clear 🙂

 

[yasalam]

Yes, I agree with Mark. By the way, I just concern about the DACT impedance which is 10K ohm (Nelson suggested 5K ohm). High output impedance makes more difficult to drive the capacitance of long cable runs, which may in part be the reason of significant high frequency losses. Anyway, if you place it on the output make sure you have short cable to your amp.

Kind regard,
Yamin😛

 

[ralf]

thank you

That`s it,

thanks to you all



Ralf

 

[Peter Daniel]

Why not do the opposite. Insert fixed voltage divider at the output and DACT pot at the input. Since you might be concerned with the high impedance (10K) of DACT pot at the output the fixed voltage divider can be any impedance, preferably less than 500 ohm. In case you need more gain you can just use a switch or relay and remove it from the signal path.You might even use 2 or 3 different values and change it according to your needs. It only takes 2 or 3 extr resistors.

 

[mefinnis]

If you actually read Nelson's article, you will find he states:

In general, the best performance occurs with the higher value of P5, giving 10 dB gain instead of 20 dB. If you don't need the gain, use 10 dB.

Adjusting the input signal level using P1 and P2 will allow you to optimize the operating point against the signal source level. The best performance occurs at approximately 1 or 2 volts output of the circuit (assuming P3 and P4 are turned up all the way). If you are running 10dB of gain, this means an input level of .3 to .6 volts, and if your source has much higher output, you can turn down P1 and P2 so as to set the input level to this region.

Once you have obtained the optimal gain and input level, adjusting the output level with P3 and P4 will give you an effective volume control which attenuates circuit noise as well as level. Of course you can use any of these pots as volume controls as you like.

Sort of answers all relevant questions really!

cheers, mark

PS: Remember the acronym, "RTFM", occasionally helps 😉

 

[Peter Daniel]

My only concern was that 10K DACT pot at the output might be to high at some cases. If you look at the schematic of BOSOZ you notice that P4 is 5K.