Dear Valery,
I have wired my TubSuMo amp and started to test it.
Without opamp LF411 I have 1,3V at output and the trimmer (10 ohm) is now in end position. When I put opamp in place then offset goes down to 6mV. Approximately the same behaviour is there even when I switch the tube for another one.
The question is: Should I change one of the 47 ohm resistors for higher/lower value or just to leave it as it is? Or is there any other recommendation?
Thanks in advance,
Ladislav
I have wired my TubSuMo amp and started to test it.
Without opamp LF411 I have 1,3V at output and the trimmer (10 ohm) is now in end position. When I put opamp in place then offset goes down to 6mV. Approximately the same behaviour is there even when I switch the tube for another one.
The question is: Should I change one of the 47 ohm resistors for higher/lower value or just to leave it as it is? Or is there any other recommendation?
Thanks in advance,
Ladislav
Hi Ladislav!
Can you please drop a schematic you are using. Also - what rails voltage do you have? I will probably suggest some optimizations, based on the latest builds experience.
I have dropped the offset trimmer at the latest version of the front-end (v1.3).
At the same time - 6mv is fine - no problem at all.
Cheers,
Valery
I really need to put this amp in a case. I have the 21st century board built so really I just need to get a case. My biggest problem is that I just have so many good amps it is hard to pick one to build complete. You guys just keep coming out with new and interesting stuff. 😎
My biggest problem is that I just have so many good amps it is hard to pick one to build complete.😀
I have the same problem😉
Hi Valery,
attached is schematic I have used. Changes to resistor values as you suggested for 50V rail voltage are:
R6, R11 = 10k
R27, R28, R30, R31 = 100R
R29 = 150R
D16, D17 only one LED instead of two
I have measured 55V rail voltage but I think it will drop a bit when loaded.
Ladislav
Attachments
TubSuMo V1.3 +/-52V rails
Hi Ladislav,
Please see the final version schematics attached (V1.3).
Note - the offset trimmer is dropped, also note R27-R31, C18 values are changed, D8, D9 zeners are removed.
It also makes sense to connect both 6.3V AC heater wires to the main ground (om PSU) through 0.1uF capacitors.
As I mentioned earlier - offset within +/-10mV is perfectly fine.
You can make it smaller, is you like, fine-tuning the servo:
R13 = 100R
C12 = 0.1uF
R19 = 27K
I have also attached the voltages, measured on my lab prototype, as well as some live measurements, made particularly with this V1.3 setup (all spectrums are taken at 50W @ 8 ohm load).
Your rails are fine - no problem at all.
Also note the minor changes in the OPS schematic: R13 = 160R instead of the diode, R4-R7 values.
Cheers,
Valery
Hi Ladislav,
Please see the final version schematics attached (V1.3).
Note - the offset trimmer is dropped, also note R27-R31, C18 values are changed, D8, D9 zeners are removed.
It also makes sense to connect both 6.3V AC heater wires to the main ground (om PSU) through 0.1uF capacitors.
As I mentioned earlier - offset within +/-10mV is perfectly fine.
You can make it smaller, is you like, fine-tuning the servo:
R13 = 100R
C12 = 0.1uF
R19 = 27K
I have also attached the voltages, measured on my lab prototype, as well as some live measurements, made particularly with this V1.3 setup (all spectrums are taken at 50W @ 8 ohm load).
Your rails are fine - no problem at all.
Also note the minor changes in the OPS schematic: R13 = 160R instead of the diode, R4-R7 values.
Cheers,
Valery
Attachments
Many thanks Valery,
I will play with my TubSuMo accordingly and will report my progress, hopefully within a week or so 🙂
Ladislav
I will play with my TubSuMo accordingly and will report my progress, hopefully within a week or so 🙂
Ladislav
Hi guys,
I did not realize this thread/design existed until today, started reading it, got into the 50's, got tired, I need a break 🙂
Valery, I commend you for supporting your design builds, to this extent, a real DIY hero imo. I wish we still have Pete/OS involved, he is a swell guy as well.
Now that I finally have a garage (putting my electronics to rest for a while), I was thinking of getting a sheet-metal, brake/shear to make my own cases, since the ones that are available for purchase are very expensive, for what you get. Raw materials are cheap, in comparison to even a simple Hammond box.
Cheers, keep up the excellent work
Rick
I did not realize this thread/design existed until today, started reading it, got into the 50's, got tired, I need a break 🙂
Valery, I commend you for supporting your design builds, to this extent, a real DIY hero imo. I wish we still have Pete/OS involved, he is a swell guy as well.
Now that I finally have a garage (putting my electronics to rest for a while), I was thinking of getting a sheet-metal, brake/shear to make my own cases, since the ones that are available for purchase are very expensive, for what you get. Raw materials are cheap, in comparison to even a simple Hammond box.
Cheers, keep up the excellent work
Rick
Thank you Rick 😀
I hope Pete will be back some time - he is a great person and great designer.
Some projects became pretty mature over the time - this is one of them.
All the minor early-tests issues are gone - it's very repeatable, nice-sounding amplifier. The front-end is compatible with other kinds of OPS on the forum, including NS-OPS based series, developed by me and Jeff during the last year or so (see the link in my signature).
Custom-made cases - a great capability, so we can expect some cool builds soon, right 😉
Cheers,
Valery
The first TubSuMo experience
So I succedded to swap some parts for recommeded ones and wired one channel of my TubSuMo project.
Everything is working fine, even some part are not exactly the ones Valery stated. These are my present changes:
- Lateral MOSFET are Exicon ECX10N20 & ECX10P20
- resistor for setting of idle current had to be 220R instead of 160R since otherwise I was not able to reach 80 mA idle current
Without opamp the output DC volatage was 1.34V. When LF411 was inserted, output voltage dropped to 2mV. This is small improvement in comparison with older variant I reported a few posts earlier. The improvement I think is due to fine tune of DC subcircuit that was recommended by Valery.
I connected loadspeaker and listened for a few minutes the sound of one channel. Everything was as it should be. From the first glance the details are clearer and the bass is more punchy. The other characetristics I can not comment since it is only mono. So I will continue with other channel. I will report my progress ASAP. (This in my case means at least 4-6 weeks 😀 )
Thank you Valery for this project. This is my first attempt to make something with a tube 🙂
Ladislav
So I succedded to swap some parts for recommeded ones and wired one channel of my TubSuMo project.
Everything is working fine, even some part are not exactly the ones Valery stated. These are my present changes:
- Lateral MOSFET are Exicon ECX10N20 & ECX10P20
- resistor for setting of idle current had to be 220R instead of 160R since otherwise I was not able to reach 80 mA idle current
Without opamp the output DC volatage was 1.34V. When LF411 was inserted, output voltage dropped to 2mV. This is small improvement in comparison with older variant I reported a few posts earlier. The improvement I think is due to fine tune of DC subcircuit that was recommended by Valery.
I connected loadspeaker and listened for a few minutes the sound of one channel. Everything was as it should be. From the first glance the details are clearer and the bass is more punchy. The other characetristics I can not comment since it is only mono. So I will continue with other channel. I will report my progress ASAP. (This in my case means at least 4-6 weeks 😀 )
Thank you Valery for this project. This is my first attempt to make something with a tube 🙂
Ladislav
Hi Ladislav,
Very good progress, thank you for the update!
Bias voltage for Exicon devices appears a little bit higher, so your move from 160R to 220R is perfectly fine. I'm looking forward to seeing your listening impressions as soon as you power-on the 2-nd channel 😉
Cheers,
Valery
Very good progress, thank you for the update!
Bias voltage for Exicon devices appears a little bit higher, so your move from 160R to 220R is perfectly fine. I'm looking forward to seeing your listening impressions as soon as you power-on the 2-nd channel 😉
Cheers,
Valery
Some notes for possible diy-ers
To put TubSuMo into box is quite challenging issue. I used the box from my previous Lateral MOSFET project that did not satisfied my preferences. The dimensions inside are 30 x 34cm. I realized that I can not put there easily small transformer for heating of the tube. So I manualy made a few windings on power transformer. However in this case I can not power on heating separately.
My solution at present is prolonged connection of loadspeakers. I am using 1 meg resistor and 100uF capacitor for making time lag to switch on loadspeakers. See attached picture.
Other thing is size of output PCB from Valery. It is bigger than expecet 😕 So I had to make my own smaller one manually. Even in this case the capacitors at this OPS board are not in normal "standing position" - they are with bended leads. Otherwise it is in space conflict with power transformer.
I am still thinking about connecting heater wires via 100nF capacitor to the ground. At this moment I am thinking it directly to the box. Maybe it is not optimal solution if anyone think it should be connected to the star point let me know please. In this moment there are not any problems even without this capacitor.
The first attached picture is my power on circuit. the other one is illustration of my set up.
Ladislav
To put TubSuMo into box is quite challenging issue. I used the box from my previous Lateral MOSFET project that did not satisfied my preferences. The dimensions inside are 30 x 34cm. I realized that I can not put there easily small transformer for heating of the tube. So I manualy made a few windings on power transformer. However in this case I can not power on heating separately.
My solution at present is prolonged connection of loadspeakers. I am using 1 meg resistor and 100uF capacitor for making time lag to switch on loadspeakers. See attached picture.
Other thing is size of output PCB from Valery. It is bigger than expecet 😕 So I had to make my own smaller one manually. Even in this case the capacitors at this OPS board are not in normal "standing position" - they are with bended leads. Otherwise it is in space conflict with power transformer.
I am still thinking about connecting heater wires via 100nF capacitor to the ground. At this moment I am thinking it directly to the box. Maybe it is not optimal solution if anyone think it should be connected to the star point let me know please. In this moment there are not any problems even without this capacitor.
The first attached picture is my power on circuit. the other one is illustration of my set up.
Ladislav
Attachments
Yes - the box is relatively compact 🙄
The box I was thinking about, while designing the boards, was 435mm wide, 400mm deep and 5U tall 😀
100nF capacitors - on my prototype, they are connected to the main star ground close to PSU. They completely eliminated some minimal noise, coming from that AC wiring, making the amp dead quiet at idle. If you don't have any hum issues - you can leave it as is.
The box I was thinking about, while designing the boards, was 435mm wide, 400mm deep and 5U tall 😀
100nF capacitors - on my prototype, they are connected to the main star ground close to PSU. They completely eliminated some minimal noise, coming from that AC wiring, making the amp dead quiet at idle. If you don't have any hum issues - you can leave it as is.
Hi Thimios,
I feel honored when you are interested in my design 🙂
In fact my PCB consists of two separate designs. The first one is Bank of capacitors and the second one is delayed speaker connection on power up plus DC protection. Original idea for speaker protection is coming from Czech guru Mr. Stranka, but I am no aware if he is present at diyaudio.com.
The final design is made via merging this two boards. Please find attached both designs in Eagle layout editor.
I hope this helps.
Best regards,
Ladislav
I feel honored when you are interested in my design 🙂
In fact my PCB consists of two separate designs. The first one is Bank of capacitors and the second one is delayed speaker connection on power up plus DC protection. Original idea for speaker protection is coming from Czech guru Mr. Stranka, but I am no aware if he is present at diyaudio.com.
The final design is made via merging this two boards. Please find attached both designs in Eagle layout editor.
I hope this helps.
Best regards,
Ladislav
Listening tests of finished TubSuMo
It took me some time to finish this amp 😀 However it is ready now and I enjoy listening this machine for about two weeks. I am listening various music at various listening levels and comparing to other amps.
My previous building experience is 1x chip amp (in 1987
), 3x various Pass amps, then 2x Pavel Dudek DPA amps, 2x JLH amp and finaly Hypa 17 amp from Czech guru Mr. Stranka.
My conclusions is that this amp is in the category of real High end.
The biggest positive feature for me is reproduction of the bass. It is so beautiful that I have never had sound like this in my house. Bass guitars are more distinct and clear.
Another positive thing is reproduction of electric guitar. It is hard to say what the electric guitar exactly should sounds like. But for me it is more beautiful then in other cases. In other cathegories as voices, pianos, etc. I did not find some clear advantage or disadvantages over other machines - it sounds as it should.
If I should be very critical then less the perfect sound I found during playing Bethoven 5th symphony from Viena PO and Carlos Kleiber. For those who do not know this performance, it is demanding huge power to play all those fortissimos. In this case Hypa 17 amp was a bit more clear and in the loudest parts the separation of instruments was a bit better. Maybe the power of TubSuMo is not sufficient in my case. Still there could be difference for those who could assemble TubSuMo with NOS.
Definitely it is the best amp I have ever had.
Ladislav
It took me some time to finish this amp 😀 However it is ready now and I enjoy listening this machine for about two weeks. I am listening various music at various listening levels and comparing to other amps.
My previous building experience is 1x chip amp (in 1987
), 3x various Pass amps, then 2x Pavel Dudek DPA amps, 2x JLH amp and finaly Hypa 17 amp from Czech guru Mr. Stranka.My conclusions is that this amp is in the category of real High end.
The biggest positive feature for me is reproduction of the bass. It is so beautiful that I have never had sound like this in my house. Bass guitars are more distinct and clear.
Another positive thing is reproduction of electric guitar. It is hard to say what the electric guitar exactly should sounds like. But for me it is more beautiful then in other cases. In other cathegories as voices, pianos, etc. I did not find some clear advantage or disadvantages over other machines - it sounds as it should.
If I should be very critical then less the perfect sound I found during playing Bethoven 5th symphony from Viena PO and Carlos Kleiber. For those who do not know this performance, it is demanding huge power to play all those fortissimos. In this case Hypa 17 amp was a bit more clear and in the loudest parts the separation of instruments was a bit better. Maybe the power of TubSuMo is not sufficient in my case. Still there could be difference for those who could assemble TubSuMo with NOS.
Definitely it is the best amp I have ever had.
Ladislav
Hi Ladislav,
Thanks a lot for your detailed impressions!
Would you mind to publish some photos of your build?
It's always nice to see the pictures of the "finished product" 😀
Cheers,
Valery
Thanks a lot for your detailed impressions!
Would you mind to publish some photos of your build?
It's always nice to see the pictures of the "finished product" 😀
Cheers,
Valery