Building a symmetrical psu B1 buffer - Page 151

ra7 · 6th June 2010, 09:48 PM

I can vouch for the gigawork pot as well. It has been working well so far ~1-2 months :P

I have not had the good fortune of comparing to any of the fancier stepped ones though, and I'm not at all sad that I haven't. The DCB1 is quite stunning as it is.

william2001 · 14th June 2010, 10:36 PM

I think I'm going to call my DCB1 finished. I took care of my heat issue with more substantial "wings" on the fets. No pics, but easy enough to explain. Same length as Hypnotize, 2.75" tall (full span from bottom to top, and supports the top mesh), and .188" thick. Drilled new mounting holes for the right side buffer to move it further away from the left, and a row of holes between the two buffers in the bottom panel to allow some convection. The whole thing looks mean, and can easily run 24/7 without issue. I'm still very happy with this preamp and want it to last a long time.

Did not attempt to change the R1's again to try and balance the currents as I mentioned before. I've changed these R1's three times already, no lifted pad issues but don't want to push my luck so it will stay as is (10.4 ohms).

I think I prefer the Takman carbon films over the PRP's on the amp feeding my satellite speakers, but I'd have a hard time explaining why. Maybe just a bit more forgiving but still detailed. But close really. Anxious to get started on some other projects, maybe that Toshiba'ed F5 as I have many of the parts already.

Salas · 14th June 2010, 10:39 PM

May it serve you well a for a long time. A very inspiring build. Congratulations.

regiregi22 · 14th June 2010, 10:48 PM

Meybe the best DCB1 seen around here, Williams

Malka07 · 15th June 2010, 04:26 PM

My build is almost coming to an end, just waiting on a few more parts to arrive to finish off...so i thought id take down some measurements.

Negative Rail -10.32v
Voltage across 68r/68r 2.04v

Positive Rail +10.19v
Voltage across 68r/68r 1.73v

Do these voltages seem ok?

Some pics...taken with my phone...so not very good quality, sorry.

Salas · 15th June 2010, 04:35 PM

Within normal builds reported range. If you wanna have exact same current on both CCS you can use 56R//56R for the 1.73V side. Now you got 60mA and 50mA. How is your DC offset at audio output? What caps you used for the film cap mod?

Malka07 · 15th June 2010, 04:55 PM

Thanks Salas, I hav'nt measured the dc offsets yet...will get to that soon and report here...Also i will probably not balance the currents yet...as i have a feeling i will be hotrodding and adding some propper heat sinks...but just want to get it up and running, get it burned in, so that i can assess the difference when hotrodded, later. I have done the cap mod, from the start and used 0.22uf Ansar supersounds for this. I have also used Charcroft nude z-foils for input/output resistors

Will keep you all updated.

Alon

AndrewT · 16th June 2010, 08:28 AM

don't remove the 68//68r.
Add an extra parallel resistor to listen to the effect if any.

you have 2.04/34 = 0.06A in the higher voltage polarity.
You have 1.73/34 = 0.0509A in the lower voltage polarity.
Try adding 1.73V / {0.6-0.509} = 190r.
Use 180r or 200r or 220r. Just tack it on the back of the PCB to hear if it has an effect.

regiregi22 · 16th June 2010, 12:29 PM

Quote:

Originally Posted by AndrewT

don't remove the 68//68r.
Add an extra parallel resistor to listen to the effect if any.
.

Do that just if you want to balance currents on both rails. If you want to hottrod it, you will need to change the resistors for higher wattage ones.

Malka07 · 16th June 2010, 05:05 PM

Thank Andrew and regiregi22,

When my Ldr's arrive, i will finish up, and then listen to it as is. Let it burn in, and then i will add a 200ohm resistor that i have in my spares to balance the currents and listen for a change...i will then hotrod it and listen again for a change in sound.

When i hotrod, which resistor wattage will i need to use? i currently have 2, 1 watt 68r resistors, would it be ok for example to use???

68r(1 watt)//68r(1 watt)//15r(5 watt) = 10.408
on the 2.04v side...2.04/10.408 = 0.196ma

68r(1 watt)//68r(1 watt)//12r(5 watt) = 8.8696
on the 1.73v side...1.73/8.8696 = 0.195ma

Thanks for your help.

Alon

14th June 2010, 10:48 PM	#1504
regiregi22 diyAudio Member Join Date: May 2009 Location: Madrid (Spain)	Meybe the best DCB1 seen around here, Williams __________________ diyAudio, doing it as big as you can, JUST BECAUSE WE CAN!

15th June 2010, 04:26 PM	#1505
Malka07 diyAudio Member Join Date: Mar 2009	My Dcb1 with Optical volume control My build is almost coming to an end, just waiting on a few more parts to arrive to finish off...so i thought id take down some measurements. Negative Rail -10.32v Voltage across 68r/68r 2.04v Positive Rail +10.19v Voltage across 68r/68r 1.73v Do these voltages seem ok? Some pics...taken with my phone...so not very good quality, sorry.

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6th June 2010, 09:48 PM	#1501
ra7 diyAudio Member Join Date: Feb 2009 Blog Entries: 1	I can vouch for the gigawork pot as well. It has been working well so far ~1-2 months :P I have not had the good fortune of comparing to any of the fancier stepped ones though, and I'm not at all sad that I haven't. The DCB1 is quite stunning as it is.

14th June 2010, 10:36 PM	#1502
william2001 diyAudio Member Join Date: Sep 2001 Location: Midwest	I think I'm going to call my DCB1 finished. I took care of my heat issue with more substantial "wings" on the fets. No pics, but easy enough to explain. Same length as Hypnotize, 2.75" tall (full span from bottom to top, and supports the top mesh), and .188" thick. Drilled new mounting holes for the right side buffer to move it further away from the left, and a row of holes between the two buffers in the bottom panel to allow some convection. The whole thing looks mean, and can easily run 24/7 without issue. I'm still very happy with this preamp and want it to last a long time. Did not attempt to change the R1's again to try and balance the currents as I mentioned before. I've changed these R1's three times already, no lifted pad issues but don't want to push my luck so it will stay as is (10.4 ohms). I think I prefer the Takman carbon films over the PRP's on the amp feeding my satellite speakers, but I'd have a hard time explaining why. Maybe just a bit more forgiving but still detailed. But close really. Anxious to get started on some other projects, maybe that Toshiba'ed F5 as I have many of the parts already.

14th June 2010, 10:39 PM	#1503
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	May it serve you well a for a long time. A very inspiring build. Congratulations.

15th June 2010, 04:35 PM	#1506
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Within normal builds reported range. If you wanna have exact same current on both CCS you can use 56R//56R for the 1.73V side. Now you got 60mA and 50mA. How is your DC offset at audio output? What caps you used for the film cap mod?

15th June 2010, 04:55 PM	#1507
Malka07 diyAudio Member Join Date: Mar 2009	Thanks Salas, I hav'nt measured the dc offsets yet...will get to that soon and report here...Also i will probably not balance the currents yet...as i have a feeling i will be hotrodding and adding some propper heat sinks...but just want to get it up and running, get it burned in, so that i can assess the difference when hotrodded, later. I have done the cap mod, from the start and used 0.22uf Ansar supersounds for this. I have also used Charcroft nude z-foils for input/output resistors Will keep you all updated. Alon

16th June 2010, 08:28 AM	#1508
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	don't remove the 68//68r. Add an extra parallel resistor to listen to the effect if any. you have 2.04/34 = 0.06A in the higher voltage polarity. You have 1.73/34 = 0.0509A in the lower voltage polarity. Try adding 1.73V / {0.6-0.509} = 190r. Use 180r or 200r or 220r. Just tack it on the back of the PCB to hear if it has an effect.

16th June 2010, 05:05 PM	#1510
Malka07 diyAudio Member Join Date: Mar 2009	Thank Andrew and regiregi22, When my Ldr's arrive, i will finish up, and then listen to it as is. Let it burn in, and then i will add a 200ohm resistor that i have in my spares to balance the currents and listen for a change...i will then hotrod it and listen again for a change in sound. When i hotrod, which resistor wattage will i need to use? i currently have 2, 1 watt 68r resistors, would it be ok for example to use??? 68r(1 watt)//68r(1 watt)//15r(5 watt) = 10.408 on the 2.04v side...2.04/10.408 = 0.196ma 68r(1 watt)//68r(1 watt)//12r(5 watt) = 8.8696 on the 1.73v side...1.73/8.8696 = 0.195ma Thanks for your help. Alon