Balanced line stage Different transformer

[lykkedk]

Hello.

Because it's difficult to have 2x30 or 1x60 transformers here in Denmark :

I have a quistion, about the transformer's used to power the balanced line stage.
In the instruktions, it say's that you could use
different voltage, on the secondary, I was considerring to use 2x24, which will give about 68V, should i then have to use ex 6x9.1 zener instead of the 7x9.1 ?
6x9.1 gives about 54, and when the mosfet loss of 3.7, I will have 50VDC back, instead of 60VDC.

Anyone experimented with this ???

[janneman]

Jesper,

I would like to help you, but that is difficult, because:

I don't know what "Balanced line stage" you are talking about;
No idea about those zener strings you talk about.
What exactly do the instructions say?

Now, you probably have a specific design in mind, probably one from Nelson Pass. There are surely many people who know what you mean because they know the design. But there are also many that would be willing to help you if they only knew what you were talking about.
If you want to reach those other people also, it might be good to include some more info, like a schematic.

{Probably someone is already on my heels to explain the question; oh well, such is life}

Jan Didden

[kristijan-k]

Hello lykkedk,

The transformer voltage is not critical for the BLS
preamplifier, and it can be little different than in the manual.

The 2 x 24 V (in series 48 V) transformer could be used
for the BLS preamplifier and with 6 x 9.1 V Zener diodes.

No changes are neccesary in the main BLS circuit, even with
different power supply voltages.

Best regards,
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip

[UrSv]

Tried Elfa?

If you feel happy with 50 VA (or use one per channel) then the 2*28 or the 2*33 V from Elfa Denmark could do. Search for 56-122-88 or 56-122-96 on Elfa Danish pages. Otherwise 2*28 V at 120 VA is up to it and 200 VA with 2*33 the luxury option.

/UrSv

PS. Jan, BLS is the same as BoSoZ and is indeed a Pass deisgn and quite frequently discussed here.

[Nelson Pass]

No doubt we are referring to the Balanced Line Stage aka
BOSOZ.

This circuit is extremely tolerant of rail voltages, and you
can substitute a wide range of rail voltages. To get the
best performance, you use more voltage until the parts
get too hot. Then you get bigger sinks and bigger wattage
resistors, or just bigger value resistors.

I don't think I would bother with less than about 2 X 20V AC
as the distortion starts to climb at higher signal levels.

[lykkedk]

[Hey thanx for all the good answers !!!

[SvErD]

I've got two 2 x 28v/50 VA trafos for my BOZOS. I'm going for separate regulators for each channel. That gives me two options:
Use one trafo per channel and get about +/-35v, or
Connect the secondaries in series and share the trafos for both channels and get the full +/-60v.
What would be the recomended way?

Svein

[DJG]

Would BOZOS work on 2x30V DC instead on 2x60V DC?

regards,
DJG

[Nelson Pass]

Yes, but it performs 4 times better with double supply.

[SvErD]

So I guess the prefered solution then would be to share the two trafos?