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Old 16th September 2013, 07:26 AM   #3861
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Default Front End Upgrade

The front end is just a DAC playing into the B1. The DAC is fed from a NAS device using FLAC format.
So far I have detected very little difference between the original CD versions and the ripped versions that I am playing now, however I am working on a DAC upgrade.
My real gripe is that music ... particularly older material.. often does not have a great balance and needs a little help to compete with some newer material. This is a matter of taste, not a claim that it is closer to the original in anyway. In many cases there was no original as the final sound resulted in a multi-channel mixdown, subject to the taste of the mixing engineer. I suppose you could argue (but I won't) that I am deviating from his chosen taste?
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Old 16th September 2013, 02:28 PM   #3862
udailey is offline udailey  United States
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Dave at Cinemag might be helpful. They build transformers you would stick in the signal. These transformers will also act as a buffer. Not only that but they have awesome CMRR. There are some supposed drawbacks but they might actually be what you are looking for. They can be manufactured to intentionally change the nature of the sound. Making it warmer is one of the things they can do by using a mix of metals in the core. Anyway, its just a suggestion to get a bit of a warmer feel while having the buffering advantage and benefiting from the great CMRR without the introduction of more opamps.
A B1 at the output might still be great because if you put the pot right after the transformer you will again be needing a low output impedance which the B1 will give you.
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Old 18th September 2013, 10:03 PM   #3863
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Hi, would this BiAmp setup work:
tube phono preamp -> B1 -> PLLXO -> Tube power amps ?
I want the B1 there to provide a master volume control. It would probably improve the PLLXO performance too? I am trying to avoid active XO. Thanks! Henry
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Old 19th September 2013, 09:34 AM   #3864
AndrewT is offline AndrewT  Scotland
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If the tube phono pre-amp has a lower output impedance then the B1 can be located some distance (of cable) away from it.
If the tube phono pre-amp has a medium or higher output impedance then the B1 should be located at the output of the Tube phono and let the B1 drive the cable to the PLLXO.

What loads does the PLLXO expect on it's input and output?
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Old 19th September 2013, 09:51 AM   #3865
Ceglar is offline Ceglar  Australia
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Default Another B1 Lives..

Another B1 Buffer stage using the 2SK170B

No pot on this one, just a fixed ~10M input impedance and large 100uF Silmic output caps to drive a LF amp from 20 - 200Hz in parallel with my main amplifier.

PS is schottky bridge - a couple common mode 10R resistors, 28kuF - 130R - then 15kuF - 10k - 15uF as per the schematic, drawing an extra 38mA through a 470 bleeder on the first cap to lower the voltage a bit to those 25V rated 15kuF caps. Sets up with 18V C1, and 9V C2. Ground lift on front panel, unit will be energised with switched active from LF amp.

Enclosure and transformer were part of a regulated battery charger supply, part of an alarm system left in the ceiling space of a de commissioned factory :-)

Really quiet, and dynamic sound running full range. Really impressed, should suit its intended purpose nicely.

Thanks for making the design available, and thanks to Andrew for answering the questions needed to bring this to fruition.

Shane

B1_1.jpg

B1_2.jpg

Last edited by Ceglar; 19th September 2013 at 09:54 AM.
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Old 19th September 2013, 06:28 PM   #3866
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Quote:
Originally Posted by AndrewT View Post
If the tube phono pre-amp has a lower output impedance then the B1 can be located some distance (of cable) away from it.
If the tube phono pre-amp has a medium or higher output impedance then the B1 should be located at the output of the Tube phono and let the B1 drive the cable to the PLLXO.
I was going to put the B1 and PLLXO in the same box (no cable needed). The phonopreamp (groovewatt) output impedance is around 250ohm. The high poweramp impedance is 30K and the low is 100K. On B1 page it says that the input impedance is the 25K pot (couldn't I just put a 50K in there if I wanted higher impedance?). I seem to remember Nelson saying the output of the B1 is about 100ohms. So it should all work, right? (In case your wondering, I really haven't got a clue).

Quote:
What loads does the PLLXO expect on it's input and output?
I thought the PLLXO is designed for the impedance of the poweramps only - and just needs enough power from the preamp (and some from the B1?). I used the excel spread sheet on this site to design it:

TLS.org | Passive Line-Level Crossover

(calculation attached as a pdf)

Thanks!!!
Attached Files
File Type: pdf PLLXO calculation.pdf (97.9 KB, 31 views)
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Old 19th September 2013, 06:42 PM   #3867
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Quote:
Originally Posted by henryyyy View Post
I thought the PLLXO is designed for the impedance of the poweramps only - and just needs enough power from the preamp (and some from the B1?).
The output impedance of the pre-amp should be suitably low, you will have no issues with B1/ Matter of fast B1 circuitry is a very good choice for making a buffered PLLXO that becomes independent of amp input R.

dave
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Old 20th September 2013, 12:48 PM   #3868
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Quote:
Originally Posted by planet10 View Post
The output impedance of the pre-amp should be suitably low, you will have no issues with B1/ Matter of fast B1 circuitry is a very good choice for making a buffered PLLXO that becomes independent of amp input R.

dave

Thanks for the advice!
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Old 22nd October 2013, 07:17 AM   #3869
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Default B1 BUFFER

Hi
this is my B1 Buffer .
Pcb its from gerber fille .
2sk 170 matched to 7.8 ma at 640 mv gs... Offset is 17mv at start and after few seconds going down to 0 V when i have connect the output to input of my amp .When the output its not connected to input of my amp offset is 400mv end going down to 0v after two or three minutes
10mf-1mf Audiophiller
JLH Shunt Reg at 24V
LM 317 at 24.10 V from china
Two separate pots 25kΩ
Very detail- low dynamics- each region frequency has her own dynamic .But every frequency has its own dynamic
and this is what makes the buffer special.
Attached Images
File Type: jpg IMGP2239-1.jpg (941.0 KB, 607 views)
File Type: jpg IMGP2241-1.jpg (972.8 KB, 571 views)
File Type: jpg IMGP2235-1.jpg (963.8 KB, 532 views)
File Type: jpg IMGP2233-1`.JPG (748.8 KB, 505 views)
File Type: jpg IMGP2236-1.jpg (957.5 KB, 503 views)
File Type: jpg IMGP2232-1.jpg (978.1 KB, 233 views)

Last edited by nikosokey; 22nd October 2013 at 07:30 AM.
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Old 22nd October 2013, 08:07 PM   #3870
Arick is offline Arick  Canada
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Nice work,
Are yo planning a enclosure for it ?
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