If the B1 rev2 is 'too revealing' you might face an up-stream root-cause to your experience?
Regarding the F5 it's my experience that it causes more problems with natural reproduction than the B1 rev. 2 in the chain.
IME B1 rev2 is spot-on perfect, at least to my ears and with my implementation of the buffer (SilentSwitcher, Hypex regs & muses attenuator).
I find the B1 rev. 2 way more open and organic natural in reproduction than the G Word balanced attenuator by Bruno Putzeys (same PSU used for both).
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Both the toshiba jfets are not made any longer, although the N channel version is easier to find. The P channel version is harder to get. Also, you need a matched pair for best results. These jfets were originally designed for mc phono step up applications...not a lot of manafacturing demand for that these days. Nelson Pass and others realized that they could be used in other applications like this buffer as well. Unfortunately, since manufacturers are not interested in high performing parts like these with limited demand no one makes a modern equivalent. The world is more interested in smaller, smd parts and ic chips these days. Rightly so...you can’t put a through-hole jfet in an iPhone.
A company called Linear Systems has begun remanufacturing this jfet. You can buy matched pairs from the diyaudio store and a portion of that purchase will fund this site.
Also, a super smart guy named Salas has developed a single ended, dc coupled version called the DCB1. Do a search, long threads exist in this forum.
Like I said, buffers are not really what I like...I prefer a preamp with a little gain. Honestly, f5 doesnt even need a buffer with its 100k input impedance if you don’t want gain. I don’t believe there were any issues upstream, and these buffers were tested on 2 different systems in 2 different rooms although the speakers were both KEF r series (not known to be bright)
B1 rev 2 had a didden super reg and good ladder pot.
B1 rev1 had an smd pot and a switch mode psu as outlined in the article.
Rev2 was far more detailed and alive...shocked me at first actually. But I felt it’s presentation was wide but flat in depth. It was very good at what it does.
Rev1 was not as detailed and slower but felt more natural in presentation. This is more in line with the sound I expected to hear.
That’s what I heard...and really, neither had the appropriate gain needed for the f5 I think. But everyone has their preferences. If you want to hear every last detail I think b1 rev2 is better. It sounds good, just maybe not my desired sound. Lots of people would prefer rev2 over rev1. I just felt it was a little too revealing and ruthless. Honestly, if I toed out my speakers 5 degrees more it may have been great! Who knows.
Some of this may be related to harmonics...rev1 being single ended and rev2 having a precisely matched jfet pair which probably cancels a lot of 2nd. One could play with the harmonics on rev2 by varying jfet values and probably get the best of both worlds.
Zen Mod also has a thread on using transformers as gain after b1 rev2. It’s called “iron pre”. I may try that next...
I have a multi-amped, multi-horn system with a JMLC Iwata horn as mids and Raal in a horn on top, planning on more horns and a smaller horn for the Raal. I am having a constant headache when changing between music and movies, because the volume level is so different at the source. After going through tube amps and F5 and soon F6, I would be happy if my final solution ended up being five F6 with five B1. Trouble is the 800W bass amp, but I guess bass is always a heachache.
Does anyone have a good solution for building five B1 preamps to control five amps simulataneously? Don't say that the best solution is a rubber band on the volume knobs. I am getting old, so a remote would be nice.
Does anyone have a good solution for building five B1 preamps to control five amps simulataneously? Don't say that the best solution is a rubber band on the volume knobs. I am getting old, so a remote would be nice.
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Regarding version 1; Can somebody please explain how creating a common point(ground) at the Gate /Drain of QX01 allows the initial signal to flow through (from the source) ? I think what I am asking is, how is it biased to allow signal to pass?
I would think that at a low volume level, PX00 wouldn't allow the Gate of QX01 to reach proper bias. It's all magic to me!
Thanks!
-Tim
I would think that at a low volume level, PX00 wouldn't allow the Gate of QX01 to reach proper bias. It's all magic to me!
Thanks!
-Tim
You mean a potentiometer with presoldered resistors? I never find the right volume on those. I like a regular Alps much better for the conveniance.
I speak okay English, but never spent more than 5 minutes in an English speaking country. Yes, a "clicker" would be the goal.
I have not found the schematic for the five B1 yet.
What kind of pot or pcb board would I need then?
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I speak okay English, but never spent more than 5 minutes in an English speaking country. Yes, a "clicker" would be the goal.
I have not found the schematic for the five B1 yet.
PC board and schematic for the standard B1 are here:
PassDiy
For 5 channels I guess you can use three boards and have a spare channel.
PC board and schematic for the standard B1 are here:
PassDiy
For 5 channels I guess you can use three boards and have a spare channel.
I already built one, hardwired. I was told I coiuld control five B1 preamps with one pot.
Were you guys talking about one of those gigantic pots with multiple pots built in a row?
The part I am confused about is how QX01 operates.. Doesn't the gate need a bias voltage to allow current through the Source-Drain ? I'm confident that Mr. Pass made a functional circuit, I just don't under at how it works :s .
I tried using spice to replace QX01 with various resistors to understand the benefit of using it.
There were noticeable voltage drops. My best guess is that the JFET current source is preferred in place of a resistor to keep the voltage from dropping while providing the current . Is that correct?
Edit: B1 Rev. 1
Thanks,
Tim
There were noticeable voltage drops. My best guess is that the JFET current source is preferred in place of a resistor to keep the voltage from dropping while providing the current . Is that correct?
Edit: B1 Rev. 1
Thanks,
Tim
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Hi, please see the following message as an honest attempt to understand, and not in anyway is it meant to be offensive. It's hard to use the right words sometimes, and I don't mean to come across as rude!
I'm not sure if my question was self explanatory, overlooked, or if perhaps nobody here knows the answer? Perhaps I could phrase it a little better.
Can anybody clarify some benefits of using a JFET as a CCS in place of some of the traditional methods(ex:resistive voltage divider) ?
I'm not sure if my question was self explanatory, overlooked, or if perhaps nobody here knows the answer? Perhaps I could phrase it a little better.
Can anybody clarify some benefits of using a JFET as a CCS in place of some of the traditional methods(ex:resistive voltage divider) ?