Thanks andrewT
I finish the build last night, and powered it up with a 15v wall wart.. would 18v make a big difference?
I didn't have any stereo 25k pot laying around, so I used a 50k pot.. i heard that a 25k is ideal for "transparency" reasons.. any good place to pick one up from?
I was in heaven.. it started to sound better and better over the 2 hour period.. and then I notice that it gets louder .. to the point I had to turn down my 23 step pot about 6 steps.. is that normal??
also I had built mine (Peter Daniel inspired me) in aluminum U channel.. would there be a need to shield the top? it looks pretty slick now since you can see all the stuff inside
I will post pics later when I get home..
-joe
I finish the build last night, and powered it up with a 15v wall wart.. would 18v make a big difference?
I didn't have any stereo 25k pot laying around, so I used a 50k pot.. i heard that a 25k is ideal for "transparency" reasons.. any good place to pick one up from?
I was in heaven.. it started to sound better and better over the 2 hour period.. and then I notice that it gets louder .. to the point I had to turn down my 23 step pot about 6 steps.. is that normal??
also I had built mine (Peter Daniel inspired me) in aluminum U channel.. would there be a need to shield the top? it looks pretty slick now since you can see all the stuff inside
I will post pics later when I get home..
-joe
Last edited:
Hi,
that sounds odd?
6steps seems like something between 6dB and 18dB of extra attenuation.
Only a fault in the amp would allow that amount of extra gain.
Check the output offset. Cold, warm and hot.
turn the pot down to zero volume. Remember, that was the position that gave zero ohms at it's output.
Now remove the speaker from the amplifier.
Measure the DC voltage and the AC voltage at the speaker terminals. Start by setting your Multimeter at highest volts scale and gradually work your way down, on both AC and DC, till you get a reading.
AC voltage should be less than 1mVac preferably less than 0.1mVac.
DC voltage should be less than 50mVdc and preferably less than 10mVdc for all operating temperatures and conditions.
Now remove the speaker from the amplifier.
Measure the DC voltage and the AC voltage at the speaker terminals. Start by setting your Multimeter at highest volts scale and gradually work your way down, on both AC and DC, till you get a reading.
AC voltage should be less than 1mVac preferably less than 0.1mVac.
DC voltage should be less than 50mVdc and preferably less than 10mVdc for all operating temperatures and conditions.
Banned
Joined 2002
Banned
Joined 2002
I built within the last weeks two versions of B1 buffers. I like it very much and I am looking for the right place within my sound chain to use them.
For sure, I use a B1 after the output trannies of my CS4398 DAC.
My first take was based on a strip board with 2SK389 in the BL version. Symmetrical PSU based on two LM317. No input cap.
The result was very impressing, also my Aikido Phono preamp sounded much better when I connected a B1 to the output.
So, I made a PCB based on the following schematics (with Express-SCH/Express-PCB, for files just drop me a PM):
Main differences to the stripboard variant:
- both channels separated from PSU by RC (10 Ohm / 220uF Oscon, bypassed by 0.1uF Wima very nearby the 2SK389)
- Dale resistors in the signal path (still missing on the picture below)
- use of the V-version of the 2SK389 (higher current)
- input cap (avoiding magnetizing of the preceding trannie during startup) 0.39uF
The board is made by the toner transfer method.
And the result?
Awesome, the second version with the higher current beats everything I used as linedriver before.
Thanks for the nice and simple circuit, Nelson!
Franz
/Edit
BOM
Br301 EDF1B
Br401 EDF1B
C1 0.39uF
C2 10uF
C3 220uF
C4 220uF
C101 0.39uF
C102 10uF
C103 220uF
C104 220uF
C301 1000uF
C302 0.1uF
C303 10uF
C304 1uF
C401 1000uF
C402 0.1uF
C403 10uF
C404 1uF
C101a 0.01uF
C102a 0.1uF
C103a 0.33uF
C104a 0.33uF
C1a 0.01uF
C2a 0.1uF
C3a 0.33uF
C4a 0.33uF
D301 2N4148
D302 2N4148
D303 LED
D401 2N4148
D402 2N4148
D403 LED
P301 1k
P401 1k
R1 330R
R2 1M
R3 330R
R4 1M
R5 100k
R6 10R
R7 10R
R101 330R
R102 1M
R103 330R
R104 1M
R105 100k
R106 10R
R107 10R
R301 100R
R304 R-LED
R401 100R
R404 R-LED
U1 2SK389
U101 2SK389
U301 LT317
U401 LT317
For sure, I use a B1 after the output trannies of my CS4398 DAC.
My first take was based on a strip board with 2SK389 in the BL version. Symmetrical PSU based on two LM317. No input cap.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The result was very impressing, also my Aikido Phono preamp sounded much better when I connected a B1 to the output.
So, I made a PCB based on the following schematics (with Express-SCH/Express-PCB, for files just drop me a PM):
An externally hosted image should be here but it was not working when we last tested it.
Main differences to the stripboard variant:
- both channels separated from PSU by RC (10 Ohm / 220uF Oscon, bypassed by 0.1uF Wima very nearby the 2SK389)
- Dale resistors in the signal path (still missing on the picture below)
- use of the V-version of the 2SK389 (higher current)
- input cap (avoiding magnetizing of the preceding trannie during startup) 0.39uF
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The board is made by the toner transfer method.
And the result?
Awesome, the second version with the higher current beats everything I used as linedriver before.
Thanks for the nice and simple circuit, Nelson!
Franz
/Edit
BOM
Br301 EDF1B
Br401 EDF1B
C1 0.39uF
C2 10uF
C3 220uF
C4 220uF
C101 0.39uF
C102 10uF
C103 220uF
C104 220uF
C301 1000uF
C302 0.1uF
C303 10uF
C304 1uF
C401 1000uF
C402 0.1uF
C403 10uF
C404 1uF
C101a 0.01uF
C102a 0.1uF
C103a 0.33uF
C104a 0.33uF
C1a 0.01uF
C2a 0.1uF
C3a 0.33uF
C4a 0.33uF
D301 2N4148
D302 2N4148
D303 LED
D401 2N4148
D402 2N4148
D403 LED
P301 1k
P401 1k
R1 330R
R2 1M
R3 330R
R4 1M
R5 100k
R6 10R
R7 10R
R101 330R
R102 1M
R103 330R
R104 1M
R105 100k
R106 10R
R107 10R
R301 100R
R304 R-LED
R401 100R
R404 R-LED
U1 2SK389
U101 2SK389
U301 LT317
U401 LT317
Last edited:
Marantzed B1!
Hi,
I just finished my B1 using Nelson's boards. There are a few pics attached.
There were a couple of minor problems en route:
1) Several of the components were too large for the board. UK suppliers's problem perhaps? Anyway, it caused me to mount the big electrolytics on the back of the aluminium mounting plate, and set the whole thing vertical.
2) There was a typo in one of the documents (drain to source connection) which could have caused the JFets to reversed... spotted that one quickly.
Apart from that the whole thing was smooth. Using and internal regulated supply it all worked first time.... though I did have to upgrade to a toroidal transformer because of the buzzing from the first standard transformer.
The chassis problem was solved by my local HiFi shop saying they had some "unrepairable" insurance amps to throw away. All that was wrong were burnt out power transistors in the Marantz PM-66SE integrated amp. I took this for my chassis as a bonus got a good cabinet, complete switching, remote control volume and mute. All I had to do was fake the power transistors working so that the mute relay would work.. it was permanently protecting everything. Because of strange voltages (and many of them) used in the Marantz, I decided to leave the original transformer in place. It is vastly more than the amp needs, but it was the simplest approach.
So after all this the result? I have been comparing the buffer to my previous pre-amp, the Pass X2. Generally the sound is more open with better dynamics and somehow sounds cleaner. The detail and stage depth also seems improved. Although it has been excellent I am afraid the X2 is destined for eBay, together with its matching Aleph, as soon as the F5 is finished.
I owe Nelson a real vote of thanks for keeping this hobby going and making it so worthwhile
George
Hi,
I just finished my B1 using Nelson's boards. There are a few pics attached.
There were a couple of minor problems en route:
1) Several of the components were too large for the board. UK suppliers's problem perhaps? Anyway, it caused me to mount the big electrolytics on the back of the aluminium mounting plate, and set the whole thing vertical.
2) There was a typo in one of the documents (drain to source connection) which could have caused the JFets to reversed... spotted that one quickly.
Apart from that the whole thing was smooth. Using and internal regulated supply it all worked first time.... though I did have to upgrade to a toroidal transformer because of the buzzing from the first standard transformer.
The chassis problem was solved by my local HiFi shop saying they had some "unrepairable" insurance amps to throw away. All that was wrong were burnt out power transistors in the Marantz PM-66SE integrated amp. I took this for my chassis as a bonus got a good cabinet, complete switching, remote control volume and mute. All I had to do was fake the power transistors working so that the mute relay would work.. it was permanently protecting everything. Because of strange voltages (and many of them) used in the Marantz, I decided to leave the original transformer in place. It is vastly more than the amp needs, but it was the simplest approach.
So after all this the result? I have been comparing the buffer to my previous pre-amp, the Pass X2. Generally the sound is more open with better dynamics and somehow sounds cleaner. The detail and stage depth also seems improved. Although it has been excellent I am afraid the X2 is destined for eBay, together with its matching Aleph, as soon as the F5 is finished.
I owe Nelson a real vote of thanks for keeping this hobby going and making it so worthwhile
George
Attachments
Just finished, my first DIY audio project in 40 years. Had lots of help from Tom Ishimoto of Northridge Electronics, who soldered all the components to the board & tested it before assembly into the enclosure. The cruddy solder joints are mine. Box is from The Container Store ($14.99), not the best choice as I had to counter-sink all the holes. Fun project, and it sounds great. Many thanks, Nelson!
Attachments
ps to above post: Tom had all the resistors on hand, so I only had to buy the capacitors, RCA terminals, pots, knobs, wall wart, etc., which I got from Mouser for about $80.00.
The knobs are worth mentioning because to me they look practically identical to the First Watt knobs. Nice! The Mouser description is: "450-3000 Eagle Knobs and Dials, Aluminum 1.00"D, US HTS 8538.90.8060 ECN EAR99", $6.05 each. They fit a 1/4" shaft and have 2 set-screws each.
If anybody knows of an enclosure that looks just like the First Watt version, please post.
I couldn't find anything on the Bud Industries or Hammond sites that came close.
I'm thinking of building another one of these.
The knobs are worth mentioning because to me they look practically identical to the First Watt knobs. Nice! The Mouser description is: "450-3000 Eagle Knobs and Dials, Aluminum 1.00"D, US HTS 8538.90.8060 ECN EAR99", $6.05 each. They fit a 1/4" shaft and have 2 set-screws each.
If anybody knows of an enclosure that looks just like the First Watt version, please post.
I couldn't find anything on the Bud Industries or Hammond sites that came close.
I'm thinking of building another one of these.
Last edited:
I have been through my parts bins and have come to the conclusion that I have just about everything to put one of these together...so my question is - What is the best way to obtain a board for this little project? The Pass DIY site has a sort of conveluted process where one has to download and fill out an order form and the either send or fax it in...and if you are using a credit card, you have to wait to get a call...etc. Would it be bad if I just called the number listed and tried to order a board (and FETs)? I am asking because I don't want to offend anyone. Did you guys (others with boards follow this process). I guess that I have been spoiled by easy e-commerce!
Thanks,
Wayne
Thanks,
Wayne
I am a little confused. If I were to run a B1 with an amp that does not have a volume control from a source that does not have a volume control, do I need to add a volume control? Or do the 25K pots act as the volume control?
I am not sure if you are supposed to adjust the pots to optimize your "system" impedance and THEN add your volume control either up or down stream?
I am not sure if you are supposed to adjust the pots to optimize your "system" impedance and THEN add your volume control either up or down stream?
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