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Old 8th March 2007, 11:44 PM   #11
Vix is online now Vix  Yugoslavia
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Quote:
Originally posted by Zen Mod
B200 still?
Yes, it's love and hate relationship. At the moment I put them in ML TL boxes previously used for Fostex FE206. That was Martin J.King project 5. http://www.quarter-wave.com/Project05/Project05.html

I used to fill the port with foam, (without it was sometimes boomy). So it worked more like sealed box, at least until I make my mind for an OB. On the other hand, Fostexes are waiting for a BIB. As things look now, I am going to have two setups, one with B200 's, OB in one room, and a BIB with FE206 in another. F2 is fine with B200, nice for easy evening listening, but not louder. ZV9 is better, overall. I am also using a pair of B&W's 601, with two sealed 12" sealed subs, just for reference, but I prefer the sound of fullrangers. B&w's are more calm, but sometimes boring.

Short explanation of the "items" on a picture: Top: ZEN V9 (used to be zen V3). CD -player: Rotel RCD-02. Below that is what looks like
JVC equalizer. It is not. It's a BOZ in a new enclosure. On top of it is a chocolate can that houses an active X-over for the two 12" sealed subwoofers. They are powered by a smallish amp at the bottom (looks like a satellite receiver, in fact is was a satellite receiver until I put an LM3886 in it).

Overall, I am getting good sound out of my system, but feel that with a little more work, it could be modified to sound better. Somehow I get an impression that, apart from the speakers that did not get appropriate "home" yet, BOZ is the "bottleneck". That's why I was considering building another preamp. I was wondering about BOSOZ, then almost decided on Aleph P 1.0 and then...this circuit

So, most probably, this preamp would drive ZEN V9 with B200 on OB, but it would be nice to know that is has enough capacity to drive F4 in the future. Who knows....

Sorry for such a long post that appears to be OT, but I wanted to let you know what I use at the moment and what I'd like to do, so it could be easier for you to give a proper advice.

Big thanks to all of you, specially to Nelson. I could have never imagined that learning about amplifiers could be so motivating.

Regards,

Vix
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Old 9th March 2007, 01:21 AM   #12
Magura is offline Magura  Denmark
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Well, what's keeping us from an adapted (read downscaled) balanced version of the ZV9 ?

Magura
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Old 9th March 2007, 01:44 AM   #13
adwsail is offline adwsail  United States
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I didn't think the 389 was still available. Who has them and how much????
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Old 9th March 2007, 02:04 AM   #14
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The 2SK389 and 2SK170 are both available from LinearSystems in Fremont California:
http://www.linearsystems.com

LSK170:
http://www.linearsystems.com/datasheets/LSK170.pdf

LSK389:
http://www.linearsystems.com/datasheets/LSK389.pdf

Both are available in the three traditional current versions: A, B, and C.

-David
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Old 9th March 2007, 02:36 AM   #15
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Nelson-

I would love to see some measurements -- especially on a cascoded jfet BOSOZ. I fooled around with it for more than a year.....but gave up on it for various reasons (unbalanced to balanced conversion, implementing volume control for 5.2 channels)

To my ear, it sounded better using resistors for the CCS( 72v rails, 3000 ohms per CCS). No follower.

Using Jfet CCS's sounded similar to the resistors, but the "classic" CCS using a small signal bipolar transistor and a mosfet sounded edgy. I would be curious to get see if the meter shows a difference.....

I just drilled a few holes in my AudioXpress boards and plopped them in.
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Old 9th March 2007, 03:16 AM   #16
moe29 is offline moe29  United States
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May 2007 will be the 10 Year Anniversary of the BZLS!


(probably the best Zen article written to date)

((well, the ZenV9 is close... let's see how it looks 10 years from now!))
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Old 9th March 2007, 05:15 AM   #17
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I have done a bit of fiddling with current sources versus resistors. Yes, sometimes a resistor sounds better, specs be damned. As for why, I'm not certain. I have long held a suspicion that part of the problem is high frequency compliance problems in current sources. A resistor, at least a decent one, is going to give pretty much the same performance at any reasonable frequency.
In practical terms, a resistor of 5-10k is usually sufficient to get good results from something like a differential. If you want to use a higher resistance you will get better performance still, but at the expense (sometimes) of having to provide a higher voltage rail.
The main problem you run into is when you need a lot of current. By definition that means a low resistance, which tends to negate the things that a current source is supposed to do. You also start burning a lot of power in the resistor.
Like many things, you have to think it through. In some cases a CCS is the best solution. In others, a resistor does as well...sometimes better.

Grey
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Old 9th March 2007, 08:23 AM   #18
juma is online now juma  Germany
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Quote:
Originally posted by Nelson Pass
it is easy to envision a fully cascoded and
constant current sourced version, with output followers
if you want to "gild the lily"

Yes we want, and the lily is all for it
Like this, perhaps ?
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Old 11th March 2007, 06:49 PM   #19
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If this Jfet BOSOZ was connected only to an Aleph30, are the output coupling caps necessary? It would be great to eliminate them if possible.

-David
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Old 11th March 2007, 08:01 PM   #20
flg is offline flg  United States
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There is a DC level at the output of all these JFET BOSOZ variants. A cap will be needed either at the output of these pre's or the input of the A30. Does the A30 already have one???
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