Hmmm . . . my R7, R8, R9 and R10 are all 10k ohms, which is what came with the kit. I can switch the R7 and R8 out to 3.3K ohms and see what happens. From what I understand of the circuit a lower resistance at R7 will expose P1 to a more positive voltage which I suspect will provide the needed "base offset" to get P1 in range for appropriate adjustment.
@Rolf:
Yes, change R7 and R8 to 3.3K ohms if possible, assuming everything else is right, it will make biasing and reducing offset easier.
Thanks for checking the voltages.
Best,
Anand.
Yes, change R7 and R8 to 3.3K ohms if possible, assuming everything else is right, it will make biasing and reducing offset easier.
Thanks for checking the voltages.
Best,
Anand.
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Help an overly adventurous newbie clarify PSU plan
Hope you guys don't mind me asking too many questions to help calrify my F6 and future FW build plan. As I now have my F6 boards and parts, I am now slowly creeping forward, and taking quite a few steps back to attempt to build something that a little more than I had originally planned. 🙂
I will ask the Toroidy guy to use your more detailed spec on two 400VA transformers.
At the moment, as I want to slightly deviate from this F6 build guide, and go for a dual mono PSU. I already have the diyaudiostore Universal PSU V3.0 boards, but have not purchased any components for it, so it is still feasible for me to not use them, and follow you using SLB instead.
When you wrote SLB did you mean the Smooth Like Buttah by XRKAudio?
XRKAudio's SLB Etsy page says '*a transformer must be sized about 3-4v higher than standard CRC PSU without a capacitance multiplier to accommodate the circa 3v dropout.*'
I wanted to order two 230Vac 400VA Toroidy, if I were to use the SLB boards, would I order two transformers with two independant 18Vac secondaries, or how much higher?
So I should order two dual rail SLB boards, for a dual mono (one transformer per channel)?
Quite a few people are saying that a dual-mono supply is a very good way to go, following that advice, is the above plan OK, so that I can just replace the 'standard' F6 build PSU & single Antek tranformer, with two 400VA Toroidy, and two dual rail SLB, and then 'just' connect to the two F6 boards and continue with the rest of 6L6's F6 build guide?
Apologies to ALL for not responding to advice earlier, it takes a while for it all to churn around in my brain, and life has been a little heavy recently. I am very grateful for your patience with my over ambitious nature.
Hope you guys don't mind me asking too many questions to help calrify my F6 and future FW build plan. As I now have my F6 boards and parts, I am now slowly creeping forward, and taking quite a few steps back to attempt to build something that a little more than I had originally planned. 🙂
@Zen Mod - Thanks for taking the time to share that info. The Toroidy website only shows the construction as per the image below:
I will ask the Toroidy guy to use your more detailed spec on two 400VA transformers.
@jameshillj - thank you for all your suggestions. The LT4320 approach suggested lost me until I pieced together a little more info from poseidonsvoice, below:
@poseidonsvoice - As I am a Newbie, I am leaving the F6 board build as per the diyaudiostore using the Jensen JT123-FLPCH (I purchased the F6 boards and parts kits already).
At the moment, as I want to slightly deviate from this F6 build guide, and go for a dual mono PSU. I already have the diyaudiostore Universal PSU V3.0 boards, but have not purchased any components for it, so it is still feasible for me to not use them, and follow you using SLB instead.
When you wrote SLB did you mean the Smooth Like Buttah by XRKAudio?
XRKAudio's SLB Etsy page says '*a transformer must be sized about 3-4v higher than standard CRC PSU without a capacitance multiplier to accommodate the circa 3v dropout.*'
I wanted to order two 230Vac 400VA Toroidy, if I were to use the SLB boards, would I order two transformers with two independant 18Vac secondaries, or how much higher?
So I should order two dual rail SLB boards, for a dual mono (one transformer per channel)?
@TungstenAudio - Thanks for your guidance, i know there are other F6 build threads, but it seemed appropriate to ask about PSU related guidance here, is that ok, wasn't sure if there was a better thread.
Quite a few people are saying that a dual-mono supply is a very good way to go, following that advice, is the above plan OK, so that I can just replace the 'standard' F6 build PSU & single Antek tranformer, with two 400VA Toroidy, and two dual rail SLB, and then 'just' connect to the two F6 boards and continue with the rest of 6L6's F6 build guide?
Apologies to ALL for not responding to advice earlier, it takes a while for it all to churn around in my brain, and life has been a little heavy recently. I am very grateful for your patience with my over ambitious nature.
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If you are going to build a dual-mono supply, then a pair of 300VA transformers is still overkill. A pair of 200VA would work fine.
If using the SLB boards, then 22V secondaries are the way to go.
If using the SLB boards, then 22V secondaries are the way to go.
@TungstenAudio - thanks 22V secondaries (understood)
Would having greater than 200VA transformers future proof me for also using the PSU parts for other future possible builds (other than the F6), such as the anticipated 'While they last...' Tokin thread? or would it have no bearing?
Bit of a vague speculative question, about reusing transformers; this F6 was to gain experience before attempting anything to blow up rare Tokin parts for Mr Pass' anticipated next build.
Would having greater than 200VA transformers future proof me for also using the PSU parts for other future possible builds (other than the F6), such as the anticipated 'While they last...' Tokin thread? or would it have no bearing?
Bit of a vague speculative question, about reusing transformers; this F6 was to gain experience before attempting anything to blow up rare Tokin parts for Mr Pass' anticipated next build.
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Sure, 300VA transformers have more headroom for high bias current. That is what I used for my F6.
sorry - edited my post, without seeing that you had replied.
Every time i think i am all set to go, I piece together a little more from 'better solutions' in other peoples posts, and my plan changes.
Every time i think i am all set to go, I piece together a little more from 'better solutions' in other peoples posts, and my plan changes.
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rootscript,
Just to recap, with the SLB you will need probably need transformers with at least 20V secondaries (member TungestenAudio is using 22V IIRC).
However with standard CRC type power supply, like the one available at the diyAudio store, 22V will give you DC voltage that is too high for the F6. With 20V secondaries and a bit of sag from the Class A load, you might be just ok - maybe others can chime in?
Just to recap, with the SLB you will need probably need transformers with at least 20V secondaries (member TungestenAudio is using 22V IIRC).
However with standard CRC type power supply, like the one available at the diyAudio store, 22V will give you DC voltage that is too high for the F6. With 20V secondaries and a bit of sag from the Class A load, you might be just ok - maybe others can chime in?
I have used 22V for my SLB, it's just fine.
However, 22v is too high for the CRC type PS.
I have just received a batch of SMPS +/- 24Vdc, hope to try them out on my F6 soon.
However, 22v is too high for the CRC type PS.
I have just received a batch of SMPS +/- 24Vdc, hope to try them out on my F6 soon.
Would 20V secondaries be OK to use on all the pass amps with a CRC power supply or are there some where it would not work well?
About that transformer ...
You could get 'Toriody' to just add an extra 18v tap on each of the 22v windings for a slightly extra cost of the 300VA version - most of the power supply filters like the SLB and the simple 'juma' cap multipliers (similar to that used on the First Watt F3 amp) absorb about 4 volts off the rails to obtain a very significant improvement in sound performance without complicated arrangements or difficult to find components.
Hi 'meanie', I just received one of those Micro Audio unregulated SMPs with the output voltage of +/-28v @ 3A instead of the basic +/- 25V @3A - it's functioning perfectly under static testing and it'll be interesting to hear how it performs on the basic F6 with optional filters - I've got the original 'Mr Evil' and PMI's simplified version, the 'X' (SLB), the Salas L-Adapter, similar to 'juma's simple followers, the old 'ripple eater', etc
Clean Power makes such a difference in the sound of any amp, IMO.
You could get 'Toriody' to just add an extra 18v tap on each of the 22v windings for a slightly extra cost of the 300VA version - most of the power supply filters like the SLB and the simple 'juma' cap multipliers (similar to that used on the First Watt F3 amp) absorb about 4 volts off the rails to obtain a very significant improvement in sound performance without complicated arrangements or difficult to find components.
Hi 'meanie', I just received one of those Micro Audio unregulated SMPs with the output voltage of +/-28v @ 3A instead of the basic +/- 25V @3A - it's functioning perfectly under static testing and it'll be interesting to hear how it performs on the basic F6 with optional filters - I've got the original 'Mr Evil' and PMI's simplified version, the 'X' (SLB), the Salas L-Adapter, similar to 'juma's simple followers, the old 'ripple eater', etc
Clean Power makes such a difference in the sound of any amp, IMO.
I'm using Toroidys with 20V secondaries on my builds. Our mains voltage here usually is around 225-230V, so a smigden under nominal, and depending on load, I'm coming out with DC 24-25V rails after a CLC supply (chokes with less than 0R1 DCR).
I haven't used the Supreme Audio from Toroidy so far - besides much more expensive, they are also a fair bit larger. Gets tight with two of them even in 4U/400 chassis. So far, I have been very happy with the Audio Grade Toroidys.
Regards, Claas
I haven't used the Supreme Audio from Toroidy so far - besides much more expensive, they are also a fair bit larger. Gets tight with two of them even in 4U/400 chassis. So far, I have been very happy with the Audio Grade Toroidys.
Regards, Claas
The F6 lives!
Anand:
I did as you suggested and exchanged R7 and R8 for 3.3K ohm resistors. I was able to set the bias to 0.500 V AND was able to get the offset to within -100 mV of zero. I then had an aha moment, inspired by your suggestion to change the R7 and R8 resistors . . . those passive components are only in there to allow you to set the bias and offset . . . so then I had the liberty to drop the R7 resistor to a 1K, and WHALA! . . . with bias set at 0.500V I was finally able to drop the offset to zero! Then I reproduced the same thing on the other channel because I noticed the same behavior with respect to setting the bias and offset (I also replaced the "smoked R4" with a 1/2 watt resistor). Finally, I was in the right neighborhood to adjust everything after a few hours of temperature stabilization and interim potentiometer tweaking.
Incorporated the amplifier into my stereo system and she works! Thanks so much!!
Oh . . . and btw, my powersupply does indeed have 15000 uF capacitors to answer one of your prior questions.
Anand:
I did as you suggested and exchanged R7 and R8 for 3.3K ohm resistors. I was able to set the bias to 0.500 V AND was able to get the offset to within -100 mV of zero. I then had an aha moment, inspired by your suggestion to change the R7 and R8 resistors . . . those passive components are only in there to allow you to set the bias and offset . . . so then I had the liberty to drop the R7 resistor to a 1K, and WHALA! . . . with bias set at 0.500V I was finally able to drop the offset to zero! Then I reproduced the same thing on the other channel because I noticed the same behavior with respect to setting the bias and offset (I also replaced the "smoked R4" with a 1/2 watt resistor). Finally, I was in the right neighborhood to adjust everything after a few hours of temperature stabilization and interim potentiometer tweaking.
Incorporated the amplifier into my stereo system and she works! Thanks so much!!
Oh . . . and btw, my powersupply does indeed have 15000 uF capacitors to answer one of your prior questions.
what you have in place of Z1 and Z2 ?
you'll easily overcook something with 1K in R7/R8 position
1K is allowing around 18mA to go further , and that's not good, at least not in my book - to overcook zener, or LED diodes if you have them instead
all part names ref. to schm in post #1
you'll easily overcook something with 1K in R7/R8 position
1K is allowing around 18mA to go further , and that's not good, at least not in my book - to overcook zener, or LED diodes if you have them instead
all part names ref. to schm in post #1
+1.
What do you have for Z1 and Z2 again? What part number or zener voltage?
You should be able to set bias and offset with R7 and R8 at 3.3K ohms. Hopefully you have waited a good 30 minutes or so since getting the offset to stay under 20mV will take some time until thermal equilibrium is achieved.
Best,
Anand.
What do you have for Z1 and Z2 again? What part number or zener voltage?
You should be able to set bias and offset with R7 and R8 at 3.3K ohms. Hopefully you have waited a good 30 minutes or so since getting the offset to stay under 20mV will take some time until thermal equilibrium is achieved.
Best,
Anand.
Rolf, as ZM and Anand have pointed out, you shouldn't need 1k at R7 and R8.
Can you please verify Z1, Z2 part values and measure the voltage across them?
Also, can you please check your trimmer part values (especially P1)?
If that part is somewhat lower in value than 5K then it can drain enough current to cause a problem.
Can you please verify Z1, Z2 part values and measure the voltage across them?
Also, can you please check your trimmer part values (especially P1)?
If that part is somewhat lower in value than 5K then it can drain enough current to cause a problem.
Hello ... working my way through troubleshooting a pair of F6 boards. Insight from others revealed that my Q4 should not be LSK170F and those have been changed to LSJ74's.
Upon powering up the two boards it seemed that something is still not correct.
I set out to confirm that I have the correct components where they belong and that everything measures as it should which raised a question. Can I measure resistors mounted on a circuit board (not energized) and expect them to measure correctly?
I think I can because most of them measure correctly, but there are some exceptions. It would seem that R7, R8 & R9 are supposed to be 10K but strangely they all measure incorrectly. On my A board R7,R8 & R9 all measure at 3.3K and on the B board R7 & R8 are also 3.3K and R9 is 134 ohms.
Also, regarding Z1 & Z2, specs call for IN4733 5.1v devices and I have utilized IN5231B which I am assuming are 5.1v devices. I do not know if this change is acceptable, or not?
And finally, when installing the Zener diodes for Z1 and Z2, I installed the diodes with the black band towards the point end of the triangle. But I do not know if this is correct.
FWIW, my DIY V3 power supply and Antek AS3218 seem all good showing the expected values: A- = 23.77 vdc and A+ = 23.88 vdc.
Thank you for any assistance offered.
Upon powering up the two boards it seemed that something is still not correct.
I set out to confirm that I have the correct components where they belong and that everything measures as it should which raised a question. Can I measure resistors mounted on a circuit board (not energized) and expect them to measure correctly?
I think I can because most of them measure correctly, but there are some exceptions. It would seem that R7, R8 & R9 are supposed to be 10K but strangely they all measure incorrectly. On my A board R7,R8 & R9 all measure at 3.3K and on the B board R7 & R8 are also 3.3K and R9 is 134 ohms.
Also, regarding Z1 & Z2, specs call for IN4733 5.1v devices and I have utilized IN5231B which I am assuming are 5.1v devices. I do not know if this change is acceptable, or not?
And finally, when installing the Zener diodes for Z1 and Z2, I installed the diodes with the black band towards the point end of the triangle. But I do not know if this is correct.
FWIW, my DIY V3 power supply and Antek AS3218 seem all good showing the expected values: A- = 23.77 vdc and A+ = 23.88 vdc.
Thank you for any assistance offered.
1N5231 is 5.1V jobbie
regarding everything else - resolder and lift one leg of part , then check with measurement
band on diode body goes on side where stripe is on pcb ; you have that most likely in any basic electronics book, same as wiki page (click me!) and numerous tutorials
nothing wrong that you asked here, but reading these books can help you immensely in basics and later in advanced area, in much more effective and pleasant way than typing questions ...... especially when you read something you even don't know that you don't know
happens to me all the time
regarding everything else - resolder and lift one leg of part , then check with measurement
band on diode body goes on side where stripe is on pcb ; you have that most likely in any basic electronics book, same as wiki page (click me!) and numerous tutorials
nothing wrong that you asked here, but reading these books can help you immensely in basics and later in advanced area, in much more effective and pleasant way than typing questions ...... especially when you read something you even don't know that you don't know
happens to me all the time
ZM, 2 picoDumbs,
Changes done as advised:
- 3 x Green LEDs installed
- Changed R3 and R4 on Tea-Bag PCB (corresponds to R7, R8 on diyAudio store PCB) to lower value: 2.9K ohms in place of 10k ohms
Sounds smoother with very good mid-range separation. However perception of the bass is that it is a little softer than before. Rail voltage +/- 23.5 after load, bias @ 1.3 amps.
What can be the next set of mods? Change IRFP240 to IRFP150 for higher damping factor?
https://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-668.html#post6017101
Changes done as advised:
- 3 x Green LEDs installed
- Changed R3 and R4 on Tea-Bag PCB (corresponds to R7, R8 on diyAudio store PCB) to lower value: 2.9K ohms in place of 10k ohms
Sounds smoother with very good mid-range separation. However perception of the bass is that it is a little softer than before. Rail voltage +/- 23.5 after load, bias @ 1.3 amps.
What can be the next set of mods? Change IRFP240 to IRFP150 for higher damping factor?
https://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-668.html#post6017101
these changes alone (biasing network) can't result in any change in sound
if there is change in sound vs. previous state, it must be from different Iq
if you want tighter, yes, you can try IRFP150
if there is change in sound vs. previous state, it must be from different Iq
if you want tighter, yes, you can try IRFP150