OK, I did some more testing. It seems my sine wave generator was acting up. Now that I have it working again the 6N1P IPS is playing beautifully. So far I have only played it through the Slew mini because that was handy. It sounds wonderful. The only thing I may change is using 1/2w resistors for R11 and R29. If my math is right, 103v across 11k is nearly 1W. The 1/4W resistors seem to be holding without burning though I'm not sure why. Probably those little .6W resistors will fit right in.
One other thing I noticed is that if I bias the tube at 1V the offset is not stable. Lowering it to .8v settles it down.
So the layout seems to work fine. I will still build one with the ECC88 just to be sure.
One other thing I noticed is that if I bias the tube at 1V the offset is not stable. Lowering it to .8v settles it down.
So the layout seems to work fine. I will still build one with the ECC88 just to be sure.
Current of R25 plus current of R26 is almost same as current of R29||R11.
7,4mA + 1,7mA ~= 9,92mA. OK.
That current is almost same as current of R24.
9,9mA ~= 2,6mA ???
This does not make sense. Is the schematic correct?
PCB bottom layout of this hybrid amplifier with ecc82
Give show PCB bottom layout and PCB Top bottom layout in pdf of this hybrid amplifier with ECC82 (12AU7)
thanks!
Hi borys!The HD version is working now. There is hidden diode in the tube socket to make them look nicer
The quick home made measurements bellow, the amp is stable, there is no oscillations present when the tube heater and main psu are powered at the same time, only DC is going bit up/down until the NFB is starting to work (heater takes around 5-8s to heat up the tube).
Unfortunatly I have pulse regulated psu for the heater so there are small artefacts present at the output (with good filtered supply all is OK).
Now there is some time for the listening tests of both versions.
Suprisingly the different tube gives a bit different sound signature.
Give show PCB bottom layout and PCB Top bottom layout in pdf of this hybrid amplifier with ECC82 (12AU7)
thanks!
Tony44
http://www.diyaudio.com/forums/solid-state/264243-very-simple-hybrid-ampifier-3.html#post4132173
Hybrid work,Borys Thanks again...
http://www.diyaudio.com/forums/solid-state/264243-very-simple-hybrid-ampifier-3.html#post4132173
Hybrid work,Borys Thanks again...
Attachments
OK, so after some more testing, the 6N1P works sort of but is a little noisy. Some of the guys on the tube forum suggested that the 6N1P may need a lot higher rails to work properly. I have been testing at +-50V through my Mini slew boards. Tomorrow I will try it with my big boards so I can get the rails closer to +-77V and see if that helps. As of right now I say stick to the ECC88 schematic. I know for sure that works well.
More tomorrow.
More tomorrow.
OK, I built the boards for the ECC88 and it works perfectly. Running it at +-75V had to reduce R6 to 390R in order to get the cathode to 1V using a 1K trimmer for R9. At these voltages, R9 ends up around 100R. However, at +-40V rails, with R9 maxed at 1k the cathode is only .8V so either R9 should be 2k or R6 needs to be adjusted for different rail voltages.
Attachments
Hi Guys
The ECC88 has much higher gm than the 12AU7-ECC8 (about 3x difference) and much lower plate resistance (almost 6x difference) according to an old Brimar book I have. The 12AU7 has a mu of 20 where ECC88 is 33. In general, low-mu tends to sound smoother although in a given circuit the overall performance will be effected by gm, rp and mu.
As long as the heater voltage is within 10% of the rated value, the cathode will be at the correct temperature for proper emission. Once heated, all that is required is to get the plate positive with respect to the cathode for current to flow. That current will be limited by rp, so at low plate voltages a lower rp is beneficial if some target current is required for the rest of the circuit to function properly. In standard tube circuits, operation at very low voltage was common despite their reputation for high-voltage use. The fashion in the 90s to operate the heater at 5.5V was completely without merit. Where the heater life is extended, the cathode life suffered so overall there was no benefit.
Bimo's parallel input triodes gives the expected result of smoother sound and improved performance as the composite device has lower rp and multiplied gm compared to the single.
Have fun
The ECC88 has much higher gm than the 12AU7-ECC8 (about 3x difference) and much lower plate resistance (almost 6x difference) according to an old Brimar book I have. The 12AU7 has a mu of 20 where ECC88 is 33. In general, low-mu tends to sound smoother although in a given circuit the overall performance will be effected by gm, rp and mu.
As long as the heater voltage is within 10% of the rated value, the cathode will be at the correct temperature for proper emission. Once heated, all that is required is to get the plate positive with respect to the cathode for current to flow. That current will be limited by rp, so at low plate voltages a lower rp is beneficial if some target current is required for the rest of the circuit to function properly. In standard tube circuits, operation at very low voltage was common despite their reputation for high-voltage use. The fashion in the 90s to operate the heater at 5.5V was completely without merit. Where the heater life is extended, the cathode life suffered so overall there was no benefit.
Bimo's parallel input triodes gives the expected result of smoother sound and improved performance as the composite device has lower rp and multiplied gm compared to the single.
Have fun
Gents,
I am just starting to collect all my parts together to build the ECC88 IPS.
As Far as I can see, post 343 has the latest Schematic.
There hasn't been a BOM created detailing resistor wattage. Looking at the photo in post 391, they all look like 1/2W.
What is the minimum voltage the ECC88 IPS will work on. At this stage I only have a 45Vac transformer to play with.
I am just starting to collect all my parts together to build the ECC88 IPS.
As Far as I can see, post 343 has the latest Schematic.
There hasn't been a BOM created detailing resistor wattage. Looking at the photo in post 391, they all look like 1/2W.
What is the minimum voltage the ECC88 IPS will work on. At this stage I only have a 45Vac transformer to play with.
I used 1/4w for everything. I am going to change R11 and R29 to .6W just because measuring them they are disbursing more than 1/4W. They don't feel hot however.
Your 45vac transformer will be perfect.
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Dear Peter.
I can use +/- 48 VDC for layout below?
I can use +/- 48 VDC for layout below?
An externally hosted image should be here but it was not working when we last tested it.
![An externally hosted image](http://<a href="http://s736.photobucket.com/user/Quoc_Tri_Nguyen/media/0db613fd-9352-4865-a5dc-c5a3681df120_zpspxzoegrw.png.html" target="_blank"><img src="http://i736.photobucket.com/albums/xx5/Quoc_Tri_Nguyen/0db613fd-9352-4865-a5dc-c5a3681df120_zpspxzoegrw.png" border="0" alt=" photo 0db613fd-9352-4865-a5dc-c5a3681df120_zpspxzoegrw.png"/></a>){kind=link}
platon.rado
Nice work!! Please increase gate stoppers at the mosfets to 330/470R, the oryginal 150R ones can cause some local parasitic oscillations in some cases.
Marc
I have exacly same siemens tubes and they are superb !
nguyen
For some reason I can not see the image but 2 x 48V DC rail is ok to run those tubes.
Terry
Great work as allways.
Recently I am doing some SMPS stuff and all amp work must wait a bit.
Regards Peter
Nice work!! Please increase gate stoppers at the mosfets to 330/470R, the oryginal 150R ones can cause some local parasitic oscillations in some cases.
Marc
I have exacly same siemens tubes and they are superb !
nguyen
For some reason I can not see the image but 2 x 48V DC rail is ok to run those tubes.
Terry
Great work as allways.
Recently I am doing some SMPS stuff and all amp work must wait a bit.
Regards Peter
Hi Marc
Do you still interested on the 6SN7 octal?
Forgive me for keep asking - I do not want to bother you in case ...............
I have several good quality tubes, purchased for the Moskido (France design) amplifier.
Something went terrible wrong with that project here these forum while I ordered and collected the components.
Now I cant build the Moskito hybrid and I remain with all those parts (tubes, sockets, LatFets etc)
Would love to use them one day ...... hopefully
Greetings
Do you still interested on the 6SN7 octal?
Forgive me for keep asking - I do not want to bother you in case ...............
I have several good quality tubes, purchased for the Moskido (France design) amplifier.
Something went terrible wrong with that project here these forum while I ordered and collected the components.
Now I cant build the Moskito hybrid and I remain with all those parts (tubes, sockets, LatFets etc)
Would love to use them one day ...... hopefully
Greetings
Hi gabor,
For sure, i have good 6SN7 tube and octal socket in stock. But for moment when i can return to workshop (up to day i have pain to walk), i have to bulit OPS (my Unislewmaster version), and CFA-XH, VSHA-ECC88 IPS as i have some pcb for them. May be 2016 begining, i will send gerber to board house for 6SN7 version. I contact you at this time as min order is 10u.
Marc
For sure, i have good 6SN7 tube and octal socket in stock. But for moment when i can return to workshop (up to day i have pain to walk), i have to bulit OPS (my Unislewmaster version), and CFA-XH, VSHA-ECC88 IPS as i have some pcb for them. May be 2016 begining, i will send gerber to board house for 6SN7 version. I contact you at this time as min order is 10u.
Marc
Thank you Marc
Very likely other people interested on the octal so we can make a small GB.
That octal tube is great
By the way do you know anything about the Moskito hybrid amp on any (French) forum (in private if you do)
They closed and removed that tread in these forum and I remain with the collected parts and schematic but with out any support..
So bad when these things happen
Greetings
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