Destroyer x Amplifier...Dx amp...my amplifier

[destroyer X]

attached image.

Carlos

[destroyer X]

This is good to see how further we can go before clipping.

regards,

Carlos

[destroyer X]

I can measure this small voltage from colector to emitter...this seems that each rail will have small power dissipation into those regulator...series regulators.

regards,

Carlos

[destroyer X]

visual stimulum i can concentrate myself better.

Also i will have my daugther to operate the reverse switch.

I do not trust in me for those things...well...humans has the tendence to pre decide the result they want...so... for me, because the hard work...the optimum result is to prefer the supply.

But i want, and need, to be scientific and fair.

So...will be listening those next 14 hours...and i suppose i will conclude.

Will create moments of silent...because brain adjust.

I prefer to perceive listening... theories says that supplies are not good..or...that they need to be faster than amplifiers to result fine.

regards,

Carlos

[destroyer X]

All them telling me the same:

-"Regulators have to be faster than the amplifier to have transient response."

All rigth boys...but i am not using regulator because of transient... i am using regulator because my transformer is not holding the voltage when heavily loaded.

Also...because of transient..we can use the regulated supply...and into the regulated supply output we can install 22000uf each rail...so..we gonna have electrons for those transients (I suppose)

The idea, not only for sonic purposes....mine is for practical purposes too.

Of course, because of the Dx Precision amplifier, i need to know if those transients will be eated or not... and i have to think about costs...those condensers into the supply output makes me think

May be better to use them into the conventional, standard, common rectifiers and condensers supply.

I will check this listening... i think it will be the better way.

But will not be easy....it is sounding almost the same...but the next hours will give me more informs.

Daugther will operate the switch.

Also she will help..she had no preference..so...her evaluation counts.

regards,

Carlos

[destroyer X]

Absolutelly no difference...with electronic regulation or without, the girls perceive absolutelly nothing.

I also could not perceive.... a little bit more power without regulator..because the supply voltage is 56.5... when regulator was adjusted into 50 volts.... dinamic power only... feeling that had more bass.... and in the reality, had reproduced bass peaks with bigger voltage.

This biggest power is felt into the bass.... of course, exactly were we have the biggest power into the sound spectrum.

They start to distort almost the same power.... because the supply can loose some volts easy....bellow 50 the supply is more powerfull and you can increase power and it is difficult to go lower than 50.

The regulator have maintained the voltage also into 50....so... both sittuations had almost same voltage when the volume was up.

The electronic, adjustable circuit is still usefull when you have bigger supply voltages and you need to reduce it.. and keept it stable.

It is not bothering the sonics..also we could not perceive advantages.

regards,

Carlos

[Graham Maynard]

Hi Carlos,

If the amplifier is biased with say 50mA quiescent current at 55Vdc, then what is the quiescent current when output drive drops the rails to 48-50Vdc ?
This can affect reproduction quality during high power bursts where the loudspeaker system impedance momentarily fallss and draws the higher current which Andrew mentions.

I suppose the regulator will allow the quiescent bias to remain constant through peaks.

A zener in parallel with the bootstrap capacitor will also improve quiescent stability with rail fluctuation, without need for power regulation.

Cheers ............ Graham.

[gaetan8888]

Originally posted by Graham Maynard
Hi Carlos,

A zener in parallel with the bootstrap capacitor will also improve quiescent stability with rail fluctuation, without need for power regulation.

Cheers ............ Graham.

Hello Graham

Another interesting knowledge to learn for me....

I presume that the zener voltage are not same for most amp, so how do we calculate it ?

Let say as exemple, calculating the zener voltage for the DX standard.

Thank

Gaetan

[Graham Maynard]

Hi Gaetan,

19V is shown across C12, so I would go for a 1W 18V or 20V zener.

If the rail voltage goes higher then excess low current through R12 will be shunted by the zener and lower half of the output stage, and not be allowed to increase the VAS current where it could modify the very highly sensitive 'A-B' output stage bias potential.

However for better output stage performance the R13 to R12 ratio may be increased so that R13 can be of higher value. This allows C12 to generate a higher impedance current source for the output stage.
For example R12 could be 1k and R13 3k9, which would give 27V at the junction of R12/13 and allow a 27V zener to be used.The value of C12 should always be such as to maintain bootstrap generation at LF, its load being R12//R13. If C12 has insufficient value, then a changing LF ripple develops in the bootstrap potential and this can modify output stage bias/distortion with dynamic audio.

If a bootstrap zener can be used then the amplifier bias could be set at the rail voltage equating to that of maximum PSU loading - where the transformer regulation losses and diode/capacitor drops are greatest - and then any increase in DC through R12 when the output stage is lightly run will be shunted away through the lower half of the output stage.

All theory. What would it sound like ?

Cheers ............. Graham.

[Nordic]

Hi guys, I seem to be chaseing my tail in a circle...
I need some help...

Can one of you draw me a jig to match the input transistors at their in-circuit levels.... for the HRII

http://www.dxamp.com/images/DXHRII_amp_Sch_Ve.pdf

My previous attempt not working well...