pre-amp out to sub-amp (BD-Design)

by GC, Sunday, August 21, 2005, 03:15 (4532 days ago)

Instead of:

Q1.
A)
Input signal -> PreAmp -> Amp1 -----> Oris Horn
|--> line filter -> Amp2 -> base woofer

Can I do:

B)
Input signal -> PreAmp ------> Amp1 -----> Oris Horn
|-> line filter -> Amp2 -> base woofer

For case (A), it seems to me too high a signal level is to Amp2 as it's the output of Amp1.

Q2.
For the Horn driver, I use 8 ohm; do I have to match the base driver to 8 ohm too?


THks
Francis

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pre-amp out to sub-amp

by GC, Sunday, August 21, 2005, 03:19 (4532 days ago) @ GC

Hi,

I redrew the character diagram below with "^" to stand for "space", or else it doesn't align right.

Instead of:

Q1.
A)
Input signal -> PreAmp -> Amp1 -----> Oris Horn
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^|--> line filter -> Amp2 -> base woofer
(i.e. line filter in from Amp1)

Can I do:

B)
Input signal -> PreAmp ------> Amp1 -----> Oris Horn
^^^^^^^^^^^^^^^^^^^^^^^^^|-> line filter -> Amp2 -> base woofer
(i.e. line filter in from PreAmp)

For case (A), it seems to me too high a signal level is to Amp2 as it's
the output of Amp1.

Q2.
For the Horn driver, I use 8 ohm; do I have to match the base driver to 8
ohm too?


THks
Francis

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pre-amp out to sub-amp

by GC, Sunday, August 21, 2005, 09:57 (4532 days ago) @ GC

Hi Francis,

The signal that the line filter needs (high level) has to come from the Oris horns (or the output of amp1).

If you use the output of your pre-amplifier for the bass then the level is too low for enough bass output. In this case you'll need a buffer or extra amplfiier to increase the gain or use an active filter.

For the Horn driver, I use 8 ohm; do I have to match the base driver to 8
ohm too?

No, you can use any impedance, both drivers have there own amplifier.

Ciao,

Bert

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pre-amp out to sub-amp

by GC, Sunday, August 21, 2005, 19:25 (4532 days ago) @ GC

FYI, instead of plate amp, I chose today a 70W+70W transistor integrated amp for the base drivers. Still searching for a pair of 15" or 18" in local shops. The 70+70 Amp sounds like a tube amp in the audition room, but not sure what's in it (Tripath?):-)

I have a EL34 30W+30W amp for the Oris 200. Waiting for it to come:-)

I soldered just now a EQ RC circuit you/someone recommended in the forum (220K + 1.5mH + 470nF) for my FE206E on a Voigt Pipe I made. Hooked it up, and worked as expected, though the mid/high frequency not as bright as before.

For the 15" base driver, what kind of characteristics I should look for? PA drivers won't work?

Thks
Francis

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pre-amp out to sub-amp

by GC, Sunday, August 21, 2005, 22:16 (4531 days ago) @ GC

Hi Francis,

...and worked as expected, though the mid/high frequency not as bright as before.

Correct, that is what the EQ should do. Depending on the room and personal taste you'll need it or not. I prefer to have a good balance but if you like them better on the bright side then leave the EQ out of the system.

Also, use quality components. Cheap parts will destroy more than you'll gain...

For the 15" base driver, what kind of characteristics I should look for? PA drivers won't work?

This depends on the size of the enclosure you're planning to built, your listening level, the size of your room and what is the most important quality in the bass you are looking for. You can even use an 8" bass driver in a relative small enclosure if that suits your preferences.

The bass driver should fit the enclosure your building. PA, hifi, etc.... all can be used depending on the quality you're after.

Ciao,

Bert

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pre-amp out to sub-amp

by GC, Monday, August 22, 2005, 06:57 (4531 days ago) @ GC


[quote]Also, use quality components. Cheap parts will destroy more than you'll
gain...
[/quote]
I did use cheap parts to test now. What normally would be classified as quality components in this area? I mean what kind of components?

> > For the 15" base driver, what kind of characteristics I should look for?
[quote]PA drivers won't work?

This depends on the size of the enclosure you're planning to built, your
listening level, the size of your room and what is the most important
quality in the bass you are looking for. You can even use an 8" bass
driver in a relative small enclosure if that suits your preferences.
[/quote]

The room is 400 sq. ft close to square like, with a 9' ceiling. I don't get enough base now definitely, and the Voigt Pipe's not generating enough sound pressure. I have to put the Pipe close to the corners of the wall to get the base. Now with the EQ circuit, I could get the volume up to -2 (in the past -15) to get more base without getting too much mid and high.

I like to bring the level of details back from string instrument like violin. I don't hear rock music. I am more in jazz, string quartets, orchestrial, and human voice like opera.

The bass driver should fit the enclosure your building. PA, hifi, etc....
all can be used depending on the quality you're after.

If the cut off is at around 250 Hz, does that mean the base driver needs to cover only from say 35Hz to 250Hz, not 35Hz to 5KHz for example. I can see a variety of these from local stores, mostly PA type and car audio use base drivers, but they never mention any Thiele/Small parameters, just Watt and Impedance.

Sorry to ask these questions as actually your BD15 give a good benchmark already. I know how it feels when you already recommended the best but I still ask you for alternatives:-) Sorry about that.

Francis

Ciao,

Bert

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pre-amp out to sub-amp

by GC, Monday, August 22, 2005, 07:32 (4531 days ago) @ GC

Hi Francis,

I did use cheap parts to test now. What normally would be classified as
quality components in this area? I mean what kind of components?

MKP type of capacitors (or Beewax, paper in oil), air coils wound very tight, carbon resistors. Especially the capacitors which then will bring back more clarity.

I like to bring the level of details back from string instrument like
violin. I don't hear rock music. I am more in jazz, string quartets,
orchestrial, and human voice like opera.

You could play with the value for the resistor. If you reduce the value to half (8 ohms or even 4) then you can play with the brightness of the sound.

If the cut off is at around 250 Hz, does that mean the base driver needs
to cover only from say 35Hz to 250Hz, not 35Hz to 5KHz for example. I can
see a variety of these from local stores, mostly PA type and car audio use
base drivers, but they never mention any Thiele/Small parameters, just Watt
and Impedance.

With your choice of drivers I would choose ones with the capability to play up to 1-2kHz. For high quality drivers you'll need at least a range up to 500Hz for crossing at 250Hz.

Ciao,

Bert

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