AudioCircle
Audio/Video Gear and Systems => The Lab => Topic started by: wushuliu on 22 Aug 2010, 02:15 am
-
The DC Coupled B1 Buffer (DCB1) is a DIY project designed by Salas and others on the diyaudio.com forum. It based on the popular B1 Buffer Preamp by Nelson Pass, also from the diyaudio.com forum. There are several threads on both projects with hundreds and hundreds of pages, so I decided to do tutorials on both for those who would just like to roll up their sleeves and build.
The DCB1 takes caps out of the signal path and uses a shunt regulated power supply; the goal being greater transparency and improved sound quality. There are many testimonials to the success of this design and personally I have found it to be a worthwhile upgrade to the original B1. Plus all the pretty lights from the LEDs.
The emphasis of this thread is on building the DCB1. If you have technical questions regarding the design itself, I'd recommend posting on one of the main diyaudio.com threads as they are very responsive and far more knowledgeable than I. I'm just a solder slinger with an itchy finger. Many thanks to Salas, Tea-Bag, and others.
Main Threads:
http://www.diyaudio.com/forums/pass-labs/145201-building-symmetrical-psu-b1-buffer.html (http://www.diyaudio.com/forums/pass-labs/145201-building-symmetrical-psu-b1-buffer.html)
http://www.diyaudio.com/forums/group-buys/147075-gb-dc-coupled-b1-buffer-shunt-psus.html (http://www.diyaudio.com/forums/group-buys/147075-gb-dc-coupled-b1-buffer-shunt-psus.html) (Group Buy)
Boards
The boards are only available from the Group Buy (GB) thread listed above. There have been several versions released already and the latest GB has passed, but you can always ask if anyone has spares and/or petition/sign up for another GB. This is very fluid, so it's just best to keep an eye on that thread.
8/22/10 - There are only about a dozen boards left. If you're going to get em, get em now!!!
Contact Tea-Bag at diyaudio.com. Links below.
BOM
The Latest BOM is Blue Edition v1.0.4. You can source almost all parts from Mouser, Digikey, and Newark/Farnell. The newest board has also been designed to accommodate a greater variety of 'boutique' components.
http://www.diyaudio.com/forums/blogs/tea-bag/attachments/191d1279907485-salas-dcb1-blue-edition-blue-dcb1-v1.0.4.pdf (http://www.diyaudio.com/forums/blogs/tea-bag/attachments/191d1279907485-salas-dcb1-blue-edition-blue-dcb1-v1.0.4.pdf)
This link is from Tea-Bag's blog:
http://www.diyaudio.com/forums/blogs/tea-bag/296-salas-dcb1-blue-edition.html (http://www.diyaudio.com/forums/blogs/tea-bag/296-salas-dcb1-blue-edition.html)
MATCHED/UNMATCHED FETS
You will need 4x matched 2SK170BLs per the BOM. The easiest way to get these would be to contact 'Blues' or 'Spencer' at diyaudio, who sells them. Spencer is probably the better option as you can also get the unmatched SK170BLs from him as well.
Or you can order bulk from someplace like Ampslab and use the DMM measurement setup
to match Idss. You will want 6mA or higher. This will be explained later. If you're eyes are glazing over, then contact Spencer.
http://www.diyaudio.com/forums/swap-meet/131284-toshiba-2sk170bl-sales-49.html (http://www.diyaudio.com/forums/swap-meet/131284-toshiba-2sk170bl-sales-49.html)
Additional Equipment
DMM (Digital Multimeter) - This is a must for this build. Avoid the urge to cheap out.
As someone had mentioned in another thread, it's not just useful for audio projects, but
for testing AC/DC in any number of situations including home wiring, auto, etc. And look at her with a straight face when you say that and you should be okay. Safety first, right honey!
Solder - I prefer low temp, eutectic solder. Kester is the standard, but hard to find in
smaller quantities. Cardas Quad, however, is available on ebay in 10, 20, and 50ft. spools for dirt cheap. Melts like butter at low temp.
Iron - If you're still new to soldering and have a wonky Rat Shack soldering iron or a single-tip Weller , then an inexpensive upgrade would be this set from Part Express:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=374-100 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=374-100)
http://www.parts-express.com/pe/showdetl.cfm?&DID=7&Partnumber=374-102 (http://www.parts-express.com/pe/showdetl.cfm?&DID=7&Partnumber=374-102)
Best of all, it comes with 4 or 5 different tips (sold separately). I've found the medium sized chisel-tip
to be a godsend for quick and easy soldering. But it's just great to have a size for almost
any situation. And the adjustable temp doesn't hurt either.
10ohm Resistor - for measuring SK170BL fets
1k Resistor - for measuring LEDs
-
So you've got a whole lotta weird looking stuff in a box from Mouser, Digikey, Partsconnexion, etc. and this Baby Blue Board. So we'll just go one component type at a time, one packet a time, and put this thing together.
With the exception of the 4 matched jfets and matching LEDs, the build is straightforward. Values and part names are indicated on the board. However, as some of the components look alike (BC550s, 60s, 517, etc), double check before you solder. What I do is only open one component packet a time, add part to the board, then toss or put away the bag/packet.
I like to start with the lowest height components first. Last thing you want to do is start with the capacitors and then find they're blocking/hampering your access to resistors and LEDs, etc.
Resistors
The BOM linked above provides parts #s and tips for resistors. The new board is designed to accept larger sizes so you have a lot of flexibility.
(http://www.audiocircle.com/image.php?id=34439)
(http://www.audiocircle.com/image.php?id=34433)
(http://www.audiocircle.com/image.php?id=34434)
Note the 470 ohm is vertically placed.
(http://www.audiocircle.com/image.php?id=34435)
These 4 are critical for audio performance. If you're gonna splurge/upgrade, start here. The BOM
indicates which parts are more critical to sound quality, which is nice.
(http://www.audiocircle.com/image.php?id=34437)
The values used here will be dependent on just how far you want to push your DCB1 aka HOT-ROD :icon_twisted:. To be discussed later...
(http://www.audiocircle.com/image.php?id=34494)
(http://www.audiocircle.com/image.php?id=34495)
Schottky
Since we're in the area, put in the IN4001 Schottky.
Note the white stripe one side.
(http://www.audiocircle.com/image.php?id=34440)
Be sure that the orientation of the IN4001 matches the stripe on the board.
(http://www.audiocircle.com/image.php?id=34442)
(http://www.audiocircle.com/image.php?id=34443)
MUR120
(http://www.audiocircle.com/image.php?id=34464)
(http://www.audiocircle.com/image.php?id=34465)
Note the white line diving the MUR120s. This indicates a jumper is needed. Use some wire or a lead off a component.
(http://www.audiocircle.com/image.php?id=34466)
(http://www.audiocircle.com/image.php?id=34467)
12VDC Relay
Plop the Relay in. Then take your iron with a little solder on the tip and solder one of the legs, while your other hand keeps it in place. This will keep it more or less in place and free up both hands agsin. Now properly solder another leg, then another. Be sure to push the Relay in occasionally as you do this until it is seated flush/properly. Repeat until done.
(http://www.audiocircle.com/image.php?id=34444)
(http://www.audiocircle.com/image.php?id=34445)
-
TRANSISTORS
There are a number of them used in this design, so once again, deal with one packet/value at a time.
BC560
(http://www.audiocircle.com/image.php?id=34447)
Note the board shows you how to orient the fets. So be sure the flat of the back and rounded
front are facing the right way.
(http://www.audiocircle.com/image.php?id=34448)
(http://www.audiocircle.com/image.php?id=34449)
(http://www.audiocircle.com/image.php?id=34450)
BC517
(http://www.audiocircle.com/image.php?id=34468)
(http://www.audiocircle.com/image.php?id=34469)
BC550
(http://www.audiocircle.com/image.php?id=34470)
(http://www.audiocircle.com/image.php?id=34471)
UNMATCHED 2SK170BLs
(http://www.audiocircle.com/image.php?id=34472)
(http://www.audiocircle.com/image.php?id=34474)
(http://www.audiocircle.com/image.php?id=34475)
-
L7812
(http://www.audiocircle.com/image.php?id=34496)
(http://www.audiocircle.com/image.php?id=34497)
.1UF Bypass
(http://www.audiocircle.com/image.php?id=34498)
100UF Caps
(http://www.audiocircle.com/image.php?id=34499)
Make sure the polarity is correct. Striped side of a cap = Negative (-).
(http://www.audiocircle.com/image.php?id=34501)
(http://www.audiocircle.com/image.php?id=34502)
(http://www.audiocircle.com/image.php?id=34503)
Film or Electrolytic for these.
(http://www.audiocircle.com/image.php?id=34504)
(http://www.audiocircle.com/image.php?id=34505)
Power Supply Caps
The new board can accommodate larger sizes and values.
(http://www.audiocircle.com/image.php?id=34507)
(http://www.audiocircle.com/image.php?id=34508)
(http://www.audiocircle.com/image.php?id=34509)
-
MATCHING LEDS
A number of LEDs are used in this design. The goal is to have the voltage from one side of the LED banks match the voltage on the other. Salas recommends using 1.8v LEDs, but you'll notice that the Mouser LEDs in the BOM are a bit higher - around 1.95v. This is acceptable. The main thing is that the total voltage from the LED strings are matched on either side of the board.
The Mouser LEDs are recommended because they are very closely matched, so no need to go order and sift through a 100 LEDs to match the voltages.
However, it's still a good idea to at least test some of the LEDs from Mouser just to be sure the specs are still tightly matched. So here's an easy way to do that.
This is also useful if you have some on hand or would rather run to Radio Shack or another vendor.
You'll need your DMM, 1k ohm resistor and a 9v or 12v battery. I happen to have a AA 12v battery holder, so I used that.
(http://www.audiocircle.com/image.php?id=34560)
Although not necessary, something to hold the LEDs while checking is useful - in this case I used a cheap dip socket from Radio Shack.
(http://www.audiocircle.com/image.php?id=34553)
LED
Long Lead = Anode (+). Short Lead/Flat Back = Cathode (-)
(http://www.audiocircle.com/image.php?id=34555)
Connect one side of the 1kohm Resistor to the Battery (+), the other to the LED (+)
Connect the Battery (-) to the LED (-)
(http://www.audiocircle.com/image.php?id=34561)
Place your DMM (+) on the (+) resistor and the DMM (-) on LED (-), and record the voltage (DC)
(http://www.audiocircle.com/image.php?id=34562)
(http://www.audiocircle.com/image.php?id=34565)
As I said, the Mouser LEDs have been closely matched. To be thorough you should order a few extra and test them all, just in case.
Now start plopping them in. The board has an LED symbol with a flat back/cathode to indicate which direction you're LEDs should be facing.
(http://www.audiocircle.com/image.php?id=34568)
(http://www.audiocircle.com/image.php?id=34569)
-
JUMPERS
Several areas on the board are marked for jumpers - just a piece of wire or whatever you have handy.
This one is to be used if you bought a 12v relay.
(http://www.audiocircle.com/image.php?id=35664)
J2
(http://www.audiocircle.com/image.php?id=35665)
J3
(http://www.audiocircle.com/image.php?id=35666)
MATCHED SK170BLS
Next up, the 4 BLs w/ matching Idss. Again, note the orientation as provided by the board
(http://www.audiocircle.com/image.php?id=35658)
(http://www.audiocircle.com/image.php?id=35659)
IRFP240
Be sure to not mix up the IRFP240 and IRFP9240s, since they looks so similar.
Vertical/horizontal placement is up to you depending on if you intend to use heatsinks, sink to the chassis, etc.
(http://www.audiocircle.com/image.php?id=35660)
(http://www.audiocircle.com/image.php?id=35661)
IRFP9240
(http://www.audiocircle.com/image.php?id=35662)
(http://www.audiocircle.com/image.php?id=35663)
INPUT/OUTPUT MOLEX
(http://www.audiocircle.com/image.php?id=35667)
-
OK, the board's all populated now you need to fire her up!
TRANSFORMER
Here is a cheap 25vct Radio Shack transformer. I have used 2 of them and they work great, no problems but some have reported buzzing issues in the past.
(http://www.audiocircle.com/image.php?id=35668)
Note the center tap (CT) goes to the middle. If you have a transformer with secondaries, please refer to the manufacturer instructions for wiring the CT.
(http://www.audiocircle.com/image.php?id=35669)
Since everyone's wiring needs/preferences are different I won't go into the AC/Fuse/RCA/Potentiometer stuff. You're on your own there.
CHECKING THE VOLTAGE
Once you have your transformer and AC all set up, turn on the board. ALL LEDS SHOULD LIGHT UP!
Now, grab your Digital multimeter and check the +/- Voltage. Set your DMM to DC Volts. Place one probe to V+, the other to G. Note the voltage. Should be over 10v. Now check (V-) and G. Should be similar amount. Doesn't have to be exact. If there is a gross difference, you'll need to trouble shoot.
(http://www.audiocircle.com/image.php?id=35670)
(http://www.audiocircle.com/image.php?id=35671)
-
Volume Pots
Just a heads up. Unlike the regular B1, there is no on-board input for volume pots. You will want to wire the dcb1 inputs from whatever pot you're using.
Also, for anyone who could use multiple inputs you can check with Tea-Bag at Diyaudio.com for the Mezmerize boards. These are earlier generation boards that allow up to 6 inputs and can connect directly to a selector switch. They also have on-board volume pot wiring.
HOT ROD
Hot Rodding a DCB1 increases the current going to the board. The stock current is around 60mA(?) w/ 34ohms (those parallel 68Rs on each side). But the more current you feed the mosfets, the better the sound quality as a general rule. Salas indicates this occurs in tiers, ~200mA being the next tier, 600mA after that, and then around 2A(!). But there's a catch: Heat. The more current, the hotter those mosfets get. Stock values you can forego heatsinks, but beyond that you'll need them. I'm pushing 600mA on my DCB1, using the entire 12x12 enclosure of my integrated amp as a heatsink with the mosfets bolted to the chassis AND a fan installed. :o :flame:
Is it worth increasing the current. Yes. Definitely the 200mA tier at least. Soundstage, three-dimensionality increases.
How do you increase the current? Resistors. The resistors by the PS caps. The BOM lists parallel 68R (=34ohms) as basic value (though the board shows 47R, which is fine as well), and 10ohm 5W for hot-rodding. You do not use 2 10R per side, just 1. This a guideline, you can increase or decrease values as you deem fit.
If you do Hot-rod, it is recommended to get a slightly larger transformer, preferably a 15v w/ 50-100VA. Also the BOM lists the MUR820 diodes instead of the 120s for hot-rodding. Note their placement by the PS in the pics above.
-
Nice work, W. I should have my boards by the end of next week.
Sincere thanks for your efforts on this thread and the others you contributed to. :thumb:
-
Good on you wushuliu! :notworthy:
This is what the Lab forum is all about... :thumb:
Anand.
-
It's easier to insert the parts in the board if you bend the leads to exactly the right length. A tool like this turns out to be extremely useful:
(http://evilmadscience.com/images/emsimages/accessories/bender/bender2.jpg)
You can buy this at various places on the web. Mouser carries a couple of these - part number 5166-801 is for 1/4 watt and 1/2 watt resistors while part number 5166-901 is for 1/2 watt and 1 watt parts. I find that the smaller one is fine for most of my work.
Here are a few other sources:
http://www.productiondevices.com/Speedy%20Bend.htm (http://www.productiondevices.com/Speedy%20Bend.htm)
http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=106884 (http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=106884)
http://evilmadscience.com/partsmenu/68-bender (http://evilmadscience.com/partsmenu/68-bender)
---Gary
-
It's easier to insert the parts in the board if you bend the leads to exactly the right length. A tool like this turns out to be extremely useful:
(http://evilmadscience.com/images/emsimages/accessories/bender/bender2.jpg)
You can buy this at various places on the web. Mouser carries a couple of these - part number 5166-801 is for 1/4 watt and 1/2 watt resistors while part number 5166-901 is for 1/2 watt and 1 watt parts. I find that the smaller one is fine for most of my work.
Here are a few other sources:
http://www.productiondevices.com/Speedy%20Bend.htm (http://www.productiondevices.com/Speedy%20Bend.htm)
http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=106884 (http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=106884)
http://evilmadscience.com/partsmenu/68-bender (http://evilmadscience.com/partsmenu/68-bender)
---Gary
That would have been pretty handy alright. Thanks Gary. There really is something for everything.
-
Great DIY thread Wu...as I was perusing the pixies, I had a similar thought as GBB...then I saw his post. Never saw that neat tool he mentioned, but you can accomplish the same results using a needle nose pliers...the tapering ends allow for differing lead bend length, simply measure the component against the space on the board, use the pliers to grip where you want to bend and you are done...takes more time than the tool shown, but just about everyone has a needle nose pliers in their toolbox.
Nice job Wushu... :thumb:
-
Great DIY thread Wu...as I was perusing the pixies, I had a similar thought as GBB...then I saw his post. Never saw that neat tool he mentioned, but you can accomplish the same results using a needle nose pliers...the tapering ends allow for differing lead bend length, simply measure the component against the space on the board, use the pliers to grip where you want to bend and you are done...takes more time than the tool shown, but just about everyone has a needle nose pliers in their toolbox.
Nice job Wushu... :thumb:
This is exactly what I do. I seem to have an 'eye' for how much I should bend so it falls in perfectly flat & flush with the board. Just remember that in areas of higher current where the resistor dissipation is more than say 1 watt, you should have the the resistor standing a little bit for better heat dissipation. Probably not really an issue with this build, and more with tube amp builds, etc...
MATCHING LEDS
A number of LEDs are used in this design. The goal is to have the voltage from one side of the LED banks match the voltage on the other. Salas recommends using 1.8v LEDs, but you'll notice that the Mouser LEDs in the BOM are a bit higher - around 1.95v. This is acceptable. The main thing is that the total voltage from the LED strings are matched on either side of the board.
The Mouser LEDs are recommended because they are very closely matched, so no need to go order and sift through a 100 LEDs to match the voltages.
:o For the LED's the voltages should match on both sides of the bank, not necessarily be 5.4V DC (for 3 LED's each being 1.8V) or 9V DC (for 5 LED's). Got it, thanks. :o
Anand.
-
OK, this is about done. I'll add a little info about checking DC Offset. I won't go into wiring specifics since everyone's needs are different and there are plenty of resources for that info.
-
This is exactly what I do. I seem to have an 'eye' for how much I should bend so it falls in perfectly flat & flush with the board. Just remember that in areas of higher current where the resistor dissipation is more than say 1 watt, you should have the the resistor standing a little bit for better heat dissipation. Probably not really an issue with this build, and more with tube amp builds, etc...
:o For the LED's the voltages should match on both sides of the bank, not necessarily be 5.4V DC (for 3 LED's each being 1.8V) or 9V DC (for 5 LED's). Got it, thanks. :o
Anand.
I'll second the mouser recommendation for LED's. All the ones I have measured thus far (34 of them!) have been very close to 1.936V or thereabouts. Some are 1.934V but most are within 1.934V to 1.937V, which is super tight matching!
Anand.
-
I've started to populate my board with the resistors I have on hand. A couple questions...
What is the Hot Rod version you referred to earlier in the thread? I suspect the answer to this question may shed some light on why I have two 47R resistors when it appears the board requires four.
Also, as stated in the BOM I ordered four 68R resistors but I can't find a home for them on the board.
-
I've started to populate my board with the resistors I have on hand. A couple questions...
What is the Hot Rod version you referred to earlier in the thread? I suspect the answer to this question may shed some light on why I have two 47R resistors when it appears the board requires four.
Also, as stated in the BOM I ordered four 68R resistors but I can't find a home for them on the board.
Not sure why there is a discrepancy b/w the BOM and the board w/ these values. But neither value are considered considered hot-rod. Use the 68R resistors.
-
Wushuliu,
Just so it's clear as to which resistors I'm referring to, see the last photo of your 4th reply in this thread; It's the four brown resistors located next to the 4700uf caps. The board is marked 47R x 2 but you're suggesting to use the 68R in their place? Thanks.
-
Wushuliu,
Just so it's clear as to which resistors I'm referring to, see the last photo of your 4th reply in this thread; It's the four brown resistors located next to the 4700uf caps. The board is marked 47R x 2 but you're suggesting to use the 68R in their place? Thanks.
Yes
-
Cheers.
-
hot rod info added.
-
Now you tell me.:cry:
I figured it out this morning spending a couple hours going through the various DCB1 threads on diyaudio. Christ, there has got to be a better way of organizing information on that site.:duh:
Didn't want to guess what I'd be missing so I ordered the parts for the hot rod build.
-
Now you tell me.:cry:
I figured it out this morning spending a couple hours going through the various DCB1 threads on diyaudio. Christ, there has got to be a better way of organizing information on that site.:duh:
Didn't want to guess what I'd be missing so I ordered the parts for the hot rod build.
Sorry. I figured the hot rod option could be saved for the end because there's plenty to get taken care of before considering it. And it's a good idea to listen to it stock first I think so you can gauge the improvements when hot-rodding and thereby decide how hard you want to push.
Nice avatar, btw. I just spotted a very young Rik Mayall in the pub scene in 'An American Werewolf in London'...
-
No worries Wushuliu, if it wasn't for this thread I wouldn't have undertaken the project. I was just being lazy avoiding those monster threads at diyaudio.
'the Young Ones' were an obsession of mine when I was in my teens. I picked up the dvd set a few years back to see if the show was as funny as I remember it to be...and it was! Brilliant show imo. You can spot all these now famous English actors getting their starts on the show. Can't imagine Rik Mayall playing any other role.
-
Wushuliu,
There is something a little confusing about this board. Look dead center where the 10 LED's are installed (5 LED's per rail). I remember you saying that the flat back corresponds with the cathode or shorter lead of the LED. I also noticed that the LED's have a square hole side and a circular hole side. You'll see that the square hole for the 3 LED/rail section corresponds with the cathode, but this doesn't seem to be true for the 5 LED/rail side. So is the pictograph of the LED accurate or is it the hole shape that is accurate to designate which way the LED's should be mounted?
Anand.
-
Wushuliu,
There is something a little confusing about this board. Look dead center where the 10 LED's are installed (5 LED's per rail). I remember you saying that the flat back corresponds with the cathode or shorter lead of the LED. I also noticed that the LED's have a square hole side and a circular hole side. You'll see that the square hole for the 3 LED/rail section corresponds with the cathode, but this doesn't seem to be true for the 5 LED/rail side. So is the pictograph of the LED accurate or is it the hole shape that is accurate to designate which way the LED's should be mounted?
Anand.
Hi Anand, as confirmed on diyaudio, I followed the pictograph. When I tested the board, all LEDs lit and voltages were matched within spec...
-
Just an FYI that I forgot to mention: the dcb1 boards can also be used just as power supplies for other low current devices. Just ignore the audio part of the board and take the power straight from the +/-V and G shown in the pics...
For instance, the Hagerman Bugle phono pre... :wink:
Probably cheaper (and just as easy if not easier) than the Bugle PS.
-
Just an FYI that I forgot to mention: the dcb1 boards can also be used just as power supplies for other low current devices. Just ignore the audio part of the board and take the power straight from the +/-V and G shown in the pics...
For instance, the Hagerman Bugle phono pre... :wink:
Probably cheaper (and just as easy if not easier) than the Bugle PS.
And most likely superior in sound quality. Shunt regulation is just in a different league than series regulation imho.
Thanks for your insights on my LED orientation question :duh:
Anand.
-
(http://www.audiocircle.com/image.php?id=36826)
(http://www.audiocircle.com/image.php?id=36827)
Wanted to show off my now completed DC B1. Photos show everything mounted in a Hammond steel chassis, using the Antek trafo (from the BOM). I am using a Glass Ware Audio stepped resistor based volume control which also provides balance control options. The inside bottom of the chassis has a sheet of sticky backed linoleum tile on it, which I've found to effectively damp steel chassis ringing and vibration quite well. These shots were with everything looking neat and tidy (before wiring up the input and outputs - I use a powered sub - and the volume controls). Wushuliu populated my board (thanks AC!) for the step-by-step instructions at the start of this thread, so I was confident that everything was assembled and working correctly even before I fired the little bugger up. Compared to my original Pass B1 using PEC mono pots and battery power this DCB1 seems to have even better dynamics (amazing!), more extension at the top and bottom, perhaps slightly better imaging (more 3D), and is overall more engaging and exciting. It was a little tizzy at the top end until it had about 40 hours of settle in time, but is now accurate to the recording.
-
Nice job.
Looks like you went for the standard current version. Nichicon Gold caps, and PRP resistors right?
Anand.
-
Thanks Anand,
Yup... went with the Nichicon Gold caps and PRP resistors. I figured I could always swap out the PRPs for other more exotic resistors down the road, and/or go for the all out hot rod option. Just wanted to get a standard version put together and hear how it compared to the standard Pass B1... which I've been very happy with.
Neil
-
Wanted to show off my now completed DC B1. ... I use a powered sub....
Walkern,
Doe the DCB1 drive both a power amp and a sub without difficulty?
Wushuliu,
Thanks so much for the thread. You have given me the confidence to attempt this.
-
ajaxmike,
The B1 has an output Z of approximately 50 ohms, and will source around 5 mA. So, the parallel combination of the input impedance of the amplifier and the sub amplifier should be, as a general rule of thumb, at least 10 times greater than 50. So, suppose 50k (assuming bjt) for each the amp and the sub amp. This is (50k*50k)/(50k+50k), or 25k, which in fact is much greater than 50 ohms, so you're ok. As to the current, you're fine if it is a jfet or tube input stage in the amps. If, bjt, then things are a bit more current hungry; but, I'd be really surprised if you weren't ok too.
In short, you should be just fine. :D
-
Thank you ultrafi!
-
Hi Ajaxmike,
The B1 drives both the sub amp and my SRS Class D amp without any trouble at all. As Ultrafi noted, this should not be a problem from a technical standpoint, and indeed, my experience confirms that the DCB1 will certainly pass plenty of everything to more than one amp at a time.
Neil
-
Thanks Neil -- one less thing to worry about.
-
Hi
Just confirming; the blue board PCB described in this thread - Is it the exact same board that is currently available in the latest GB at http://www.diyaudio.com/forums/group-buys/147075-gb-dc-coupled-b1-buffer-shunt-psus-54.html#post2406762 (http://www.diyaudio.com/forums/group-buys/147075-gb-dc-coupled-b1-buffer-shunt-psus-54.html#post2406762)?
Thanks
-
Yes, but there are two different boards being offered. The 'Hypnotize' is for a single source, is hot-roddable??(is that a word?) and is the board Wushuliu so kindly showed how to assemble. The Mesmerize' should be your choice if you have more than one source.
-
I have a simple but stupid question, how do I sign up for that GB at DIY? I am a member but I am unaware of the logistics of GB.
-
Go to the thread in question and find the member Teabag. Send him a pm and he'll give you payment instructions.
-
PM sent.
I have a simple but stupid question, how do I sign up for that GB at DIY? I am a member but I am unaware of the logistics of GB.
-
Can you guys estimate the parts cost for dcb1 build.
-
With the parts listed in the BOM, a basic chassis and knobs and such, no frills RCA, IEC and speaker connectors, standard sorts of internal wiring and switching, I believe you could come in around $175. And you could easily triple that if you wanted exotic parts, audio jewelry quality chassis and connectors, etc. IMHO the design is certainly of such a high quality that spending extra to get the best parts will yield sonic benefits well worth the extra $ spent. That said, I have been thrilled with my no frills unit.
Neil
-
Thanks Neil. I think i told scott ~$80 to populate the board itself, but the rest does add up!
why can't we live in a world without enclosures, with wires hanging freely and high voltages exposed to the air... sure would be a lot cheaper.
*sigh*
-
Just ordered a mesmerize kit. Is this also hot roddable?
-
Just ordered a mesmerize kit. Is this also hot roddable?
Yes...
-
cool, is it done the same way? Modify the pertinent resistor values?
-
Yes, the only functional difference w/ Mez board from the regular board is the number of signal input/outputs.
-
Excellent! Thanks so much for the help!
-
Just wanted to post in appreciation of Wushuliu's time and effort in posting the tutorials of the B1 builds.
Ive been dragging my feet for months with the DCB1 build, because i built and dialed in the B1 buffer with TX2575 resistors and Sonicaps with teflon bypass. The B1 is an excellent preamp and has served me well, but the DCB1 is on another level.
I just got it it installed into a Hammond case using premium parts in the build.
Naked Vishay TX2575 220r resistors
Caddock MK132 1m resistor
Caddock TF020 220k resistors
Mundorf AG Audio caps
Antek 100va Transformer
Hotrodded version currently 200mA
The DCB1 has a huge soundstage and low level detail is amazing, i am listening at lower volumes because of the increased resolution. This is a very special build, thanks to Salas and Teabag for the design. Thanks to Anand for answering all my pm's. :wink:
Big thanks to Wush because i would not have attempted either build without your tutorial's. :thumb:
(http://i59.photobucket.com/albums/g295/mrnick_2006/dbb1005.jpg)
(http://i59.photobucket.com/albums/g295/mrnick_2006/dcb1002-1.jpg)
-
Congrats, Keith. It looks like a very nicely done project. Next time I'm in the Austin area, I'd like to hear it. Perhaps even bring along a Dodd buffer to do a little A/B.
Scott
-
Well done! I agree that Wushuliu deserves a big thanks for this thread, I wouldn't have built mine without it either. The DCB1 and Uriah's Lighter Note kit were big game changers for me.
-
Good work Keith, now you can wade in sonic nirvana.
I would also like to see a DCB1 versus Dodd tube buffer comparison as well.
Anand.
-
:thumb:
-
I want to build one of these. I have a LM3886 based chip amp, the MyRef revC design and don't want to spend money for nicer input caps. I want to remove my basic input caps and go DC-coupled.
I'm new to electronics and there is much I do not understand. Does the DCB1 eliminate DC at it's output ? I plan to have my only input be a Toslink to a DAC, then to a LightSpeed or other volume control and into the DCB1. Can a LightSpeed be better than software volume on a DAC (ES9018) ? Can the DCB1 be used as a headphone amp ? How much gain can a DCB1 (Hotrodded) provide ? What high-quality transformer for the HotRod (600mA ~ 2A) version ?
-
I want to build one of these. I have a LM3886 based chip amp, the MyRef revC design and don't want to spend money for nicer input caps. I want to remove my basic input caps and go DC-coupled.
I'm new to electronics and there is much I do not understand. Does the DCB1 eliminate DC at it's output ? I plan to have my only input be a Toslink to a DAC, then to a LightSpeed or other volume control and into the DCB1. Can a LightSpeed be better than software volume on a DAC (ES9018) ? Can the DCB1 be used as a headphone amp ? How much gain can a DCB1 (Hotrodded) provide ? What high-quality transformer for the HotRod (600mA ~ 2A) version ?
The DC-B1 is DC coupled, and as such does not block DC from coming in or passing through it. I've tried a Lightspeed based volume control with a DC-B1 and it is a very nice combo, but I can't say if it is better than a software based control. Since the B1 is a buffer, and does not amplify the incoming signal (only attenuates it), it may or may not work well as a headphone 'amp'. It would depend on the output characteristics of your source, and the input characteristics of your headphones. And if you read back a few posts you'll see the recommendation for a transformer for the Hot Rodded version.
Neil
-
Thanx for the fast response.
http://www.radioshack.com/product/index.jsp?productId=2102700&filterName=Brand&filterValue=RadioShack
Would this be the one ? Looks like it's time for me to read some BIG threads and see what I can find. Thank you for posting this in a circle. Sometimes it seems that if you post over there without meeting the minimum intelligence requirements you get served up.
-
Its recomended for the hotrod version you use either a 50va or 100va transformer. Antek is now making a shielded version.
http://www.antekinc.com/details.php?p=644
http://www.antekinc.com/details.php?p=660
-
Hello Folks, I recently received a fully stocked Mezmerize Board and plan to put everything together in a case this weekend, however I have a few questions that I know you good people can easily answer. :)
Wiring the Antek transformer to 110V
I have 2 Black and 2 Red wires to connect to the 110V IEC, so do both pairs need to be connected, or just one. Does it matter which wires are connected where? No ground wire is used?
Powering the Mezmerize Board with the Antek Tran 12V
Again, I have 2 Green and 2 Blue wires coming out of the transformer, how exactly do these connect to the Mesmerize Board?
Selector Switch to inputs on Mezmerize Board
Included in the bundle, was an Alpha 7M4 Selector Switch. I understand this Selector Switch connects to the boards Selector Pins and Ground, but again I am confused how this is to be wired. Any assistance/explanation as exactly how this is done would be greatly appreciated as I’m a bit/very confused.
I believe the rest is pretty straight forward, and don’t foresee any issues, however I do have a few questions, that I wouldn’t mind getting answered.
Is the Selector Switch actually in the signal path, or on the Mezmerize board is it purpose simply to engage the correct relay/input. Curious?
I plan to run an output for a Sub, in addition to an out to the Amp. No problems in doing this? And is as easy as taping a second set of RCAs of the first set of outputs?
I think that’s all my questions for now.
Again, I realize these are very simply questions, but want to avoid screw ups, and do it right the first time.
Thanx in advance for your input, Fred in Canada
(http://www.audiocircle.com/image.php?id=58401)
(http://www.audiocircle.com/image.php?id=58402)
-
Hi Fred,
I was hoping someone with more know how would chime in here... but nothing yet, so I'll offer my suggestions. I did my B1 quite a while ago, and have subsequently sold it, so relying on memory here.
1) Twist together the two red wires and connect them both to either the hot or neutral AC lead coming in. Twist together the two black wires and connect them both to the other AC lead coming in (hot or neutral). Some folks at DIY Audio suggested running a wire from the AC ground lead to the chassis, but I did not do that, and encountered no issues (hum).
2) If you track the green and blue wires coming off the trafo you'll notice there is an outlying green, and outlying blue, and a green and blue right next to one another. Connect the outlying green to one of the outside connections on the Molex connector (on the board), connect the outlying blue to the other outside connection on the Molex connector, and twist together the two adjacent wires (one blue, one green) and attach both to the center connector on the Molex connector.
Since I had the hypnotize board (which had no input switching) I can't help you with your inquiry regarding the input selector. Sorry.
And yes, you can just run a second set of outputs (one for your main amp, and one for a sub amp) by just tapping off one to the next. Worked like a champ for me.
Best of luck!
Neil
-
Thanx for the quick reply back Neil, I understand the tran wiring clearly with your explantion. :thumb:
Now if someone could clarify how the Switch Selector hooks up to the Mezmerize, that would be awesome!
Cheers, Fred in Canada
-
(http://www.audiocircle.com/image.php?id=58668)
Just finished mine, but the leds are not giving me the complete lightshow. V- is ok, but the V+ is around 7vdc
Any idea where to start looking ?
-
The LEDs probably don't light because one or more have been reversed in the chain.
BTW: I don't know if this was mentioned before, but the build document shows that the 0.22 uF capacitors were installed incorrectly. The +/- pads on the board are not oriented in the same way for both caps, which were installed assuming they were.
-
BTW: I don't know if this was mentioned before, but the build document shows that the 0.22 uF capacitors were installed incorrectly. The +/- pads on the board are not oriented in the same way for both caps, which were installed assuming they were.
What? More specifics please.
-
Guys
A brand newby here from clean, green, beautiful New Zealand.
Just today I stumbled upon this wonderful forum for the first time, so this is my first post.
QUESTION: Is the DC-Coupled (Pass) B1 Buffer Build board and BOM still an available option? If so, where do I go for ordering and help please? Appreciated.
:green:
SONDEKNZ
PS: Wonderful forum, but pretty tricky figuring out how to begin a new topic, insert signature, avatar, etc...
-
Here is the build thread and Tea-Bag is the gentleman to contact for boards.
http://www.diyaudio.com/forums/pass-labs/176723-mezmerize-dcb1-building-thread.html
-
MATCHED/UNMATCHED FETS
You will need 4x matched 2SK170BLs per the BOM.
Or you can order bulk from someplace like Ampslab and use the DMM measurement setup
to match Idss.
You will want 6mA or higher.
This will be explained later.
Hi Wushuliu, Great Thread, Thank you.
I just received some 2SK170BL's and need to match them.
You mentioned that you would explain later how to match them but I can't find it in this thread.
Can you explain how to match them and can it be done with a basic DMM?
Thanks,
Steve
(https://www.audiocircle.com/image.php?id=189687)
-
Hi Wushuliu, Great Thread, Thank you.
I just received some 2SK170BL's and need to match them.
You mentioned that you would explain later how to match them but I can't find it in this thread.
Can you explain how to match them and can it be done with a basic DMM?
Thanks,
Steve
Hm, could have sworn I did, but here's a succint explanation I found on how to do it:
hook up a simple jig with a 9v battery and a 100R resistor in series with the jfet and measure the voltage drop across the 100R resistor to find out the idss. do it with the rest to get your match.
(https://www.audiocircle.com/image.php?id=189903)
-
Hmm, the text and the diagram seem to be two different setups. The resistor drawn on the diagram appears to be 1K (or possibly 4K - the person who drew the diagram was not taught how to write (draw?) by a Catholic nun, btw) and the voltage source, while it appears to have a "9" associated with it, has some other baffling squiggle preceding that 9.
But yes, a voltage and a resistance, and then some type of Law.
-
Hmm, the text and the diagram seem to be two different setups. The resistor drawn on the diagram appears to be 1K (or possibly 4K - the person who drew the diagram was not taught how to write (draw?) by a Catholic nun, btw) and the voltage source, while it appears to have a "9" associated with it, has some other baffling squiggle preceding that 9.
But yes, a voltage and a resistance, and then some type of Law.
Yes, two examples with a 9v. One with 100R, the other 1K. I believe 1k was the one I used.