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DIY experts needed... SUT for Bellari VP129

Guys...as stated in an earlier thread I want to move to a Denon 103/103R cartridge.
What I`m using now is a Bellari VP129 phono stage, fed directly into my amp. Nothing else is in the way.
Listening level in my room could be called moderate...MAYBE (and that`s when the dial is turned all the way up).

And that`s with a Sumiko BPS EVO III @ 2.5mv.

When I change over to one of the Denons
I`d like to have some more power, a little more volume available when I want it but still leave the system as is with the exception of the step up.

So...can anyone tell me how to go about this if I go the Cinemag type route??
I`m clueless as to what I`ll need to allow me more flex ability.
Thanks in advance,
Steve
scm

Showing 4 responses by restock

restock
831 posts
 
It seems to me like you might need an active preamp in your system, since
the Bellari is not driving your amp sufficiently. I don't think you can fix this
completely with a step-up although a higher step-up gain will help. What
amp are you using?

The cinemag transformers has several possible step-up ratios, that is you can
choose between 1:9, 1:18 and 1:36. Both higher ones would give you a higher
voltage than 2.5mV after the step-up . Keep in mind that effective load the
cartridge sees is also changed and it will be worth experimenting with the two
different ratios.

FYI: Cinemag Step-up ratios
restock
831 posts
 
Here is a breakdown of voltages into the Belari:

Denon DL103R using 1:36 tap on the Cinemag:
The cartridge sees a 40 Ohm load. Voltage is 0.25mV after the step-up this is close to 10mV, which may almost overdrive the Bellari (effective gain is about 30dB due to the step-up alone). After the 30dB gain Bellari you have 0.4V which might still not be enough to drive your amp.

Denon DL103 using 1:36 tap on the Cinemag:
The cartridge sees a 40 Ohm load. Internal impedance of the 103 is 40 Ohm so that the available output voltage is half of the 0.4mV given, i.e. 0.2mV. After the step up you have about 8mV output.
restock
831 posts
 
The EVO III is putting out about a quarter of the voltage compared to the Denons after the Bellari - about 0.1 V. Comparing this to the standard 2V CD players put out that should not be enough to drive any amp directly. With the low 30dB gain of the Bellari I still can't see how that is enough to drive any amplifier directly without an additional preamp.

As for "overdriving" the Bellari - there might be a maximum input voltage for the Bellari, which you might exceed.

And do you think I can accomplish what I hoped to do ?

No, I think you will need an extra active preamp with about 20dB gain to drive your amp.
restock
831 posts
 
Yes :-)

1:36 is a lot of gain - 30dB.
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