Still agree with you 
Except the dac output is reduced to around 15-20mV and then amplified thorugh the 6N16.... Only because I like it´s sound. Bass is tight, treble is "silky" in lack of a better word, and the mid´s are to die for... nothing less
That´s the whole reason I started messin´ with the Mini-Me in the first place... I´m in love with the way 6N16B-V reproduces the whole audio spectrum
Except the dac output is reduced to around 15-20mV and then amplified thorugh the 6N16.... Only because I like it´s sound. Bass is tight, treble is "silky" in lack of a better word, and the mid´s are to die for... nothing less
That´s the whole reason I started messin´ with the Mini-Me in the first place... I´m in love with the way 6N16B-V reproduces the whole audio spectrum
Hi Ronny, hi all,
this is my version of the Mini-Me.
It`s a combination of 3 parts:
a smal PCB with the tubes and anode resistors, kathode resistors and R1, R20, R21;
the voltage supply, for each chanal one;
and the RIAA network with the coupling capacitors;
There is one problem:
one chanal has less than 0,3mV hum, but the other one has around 18-20mV!
I changed the tubes from left to right, than I changed the voltage supply from left to right, the hum ist still at the same chanal.
At least I changed the part with the RIAA network and the coupling capacitors from left to right and now the hum is at the other chanal.
So, this part makes the problem. I build an other part but the problem is still there.
May be someone has an idea??
Jacky
this is my version of the Mini-Me.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
It`s a combination of 3 parts:
a smal PCB with the tubes and anode resistors, kathode resistors and R1, R20, R21;
the voltage supply, for each chanal one;
and the RIAA network with the coupling capacitors;
There is one problem:
one chanal has less than 0,3mV hum, but the other one has around 18-20mV!
I changed the tubes from left to right, than I changed the voltage supply from left to right, the hum ist still at the same chanal.
At least I changed the part with the RIAA network and the coupling capacitors from left to right and now the hum is at the other chanal.
So, this part makes the problem. I build an other part but the problem is still there.
May be someone has an idea??
Jacky
Connections between the tubestages and riaa network should be as short as possible. Your layout does not have that.
Have you measure humm with shorted input?
Sometimes it works better when the heater supply is floating.
Disconnect ground heatersupply and ground anodesupply and place between the two grounds a 1uf nonpolar capacitor.
Have you measure humm with shorted input?
Sometimes it works better when the heater supply is floating.
Disconnect ground heatersupply and ground anodesupply and place between the two grounds a 1uf nonpolar capacitor.
Hi,
thanks for your answer.
Yes input was shorted.
Connections between the tubestages and riaa network should be as short as possible. Your layout does not have that.
Ok, that`s right. But the connections at both channals have the same size. and the hum of one channal is about a factor 100 of the other.
Sometimes it works better when the heater supply is floating.
Disconnect ground heatersupply and ground anodesupply and place between the two grounds a 1uf nonpolar capacitor.
I will test it.
Jacky
thanks for your answer.
Yes input was shorted.
Connections between the tubestages and riaa network should be as short as possible. Your layout does not have that.
Ok, that`s right. But the connections at both channals have the same size. and the hum of one channal is about a factor 100 of the other.
Sometimes it works better when the heater supply is floating.
Disconnect ground heatersupply and ground anodesupply and place between the two grounds a 1uf nonpolar capacitor.
I will test it.
Jacky
Hi Jacky....
Agree with Koifarm. You really gave yourself quite a challenge, dismantling the different sections of this phonoamp instead of keeping all parts as close together as possible with a sensible layout for ground, supply´s & signal traces.
Let´s hear how it goes
Anyone else assembled this yet?? Pictures and listening impressions would be highly appreciated
Agree with Koifarm. You really gave yourself quite a challenge, dismantling the different sections of this phonoamp instead of keeping all parts as close together as possible with a sensible layout for ground, supply´s & signal traces.
Let´s hear how it goes
Anyone else assembled this yet?? Pictures and listening impressions would be highly appreciated
I didn't read the whole thread, so I'm not sure if this yet has been discussed:
As for the schematics in post #1, I would not recommend to omit R1 if you opt for an impedance selector switch. A grid leak resistor is mandatory for any tube! So I'd chose, say, 1M for R1 and recalculate the selectable resistors to match the desired total resistance values.
Best regards!
As for the schematics in post #1, I would not recommend to omit R1 if you opt for an impedance selector switch. A grid leak resistor is mandatory for any tube! So I'd chose, say, 1M for R1 and recalculate the selectable resistors to match the desired total resistance values.
Best regards!
Thanks for the info, appreciated, but rest assured I would never build a circuit without a grid leak!
I am using a zobel in parallel with the 47k load and optimising, and now have a series of capacitors and resistors that give the flexibility to optimise my three SUTs. Measuring their performance and optimisation has been instructive for me, but I have yet to judge them against the real world, ie music...
I am using a zobel in parallel with the 47k load and optimising, and now have a series of capacitors and resistors that give the flexibility to optimise my three SUTs. Measuring their performance and optimisation has been instructive for me, but I have yet to judge them against the real world, ie music...
I populated one channel on the very nice pcb and on the bench it measures about 10mV @50Hz of ripple at the output (input shorted). Everything else including gain and RIAA curve look fine.
Now, the +B is well filtered with less than 1mV of ripple and so is heaters supply, even tried with a 12V battery and it made no difference.
I understand that the hum being at 50Hz is probably due to interference from the toroid or mains cable but they are about half meter away so I find it unlikely it picks from there.
Could someone who built it properly in a chassis let me know what is the hum level to expect? any input would be much appreciated
Now, the +B is well filtered with less than 1mV of ripple and so is heaters supply, even tried with a 12V battery and it made no difference.
I understand that the hum being at 50Hz is probably due to interference from the toroid or mains cable but they are about half meter away so I find it unlikely it picks from there.
Could someone who built it properly in a chassis let me know what is the hum level to expect? any input would be much appreciated
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I am using the pcb's provided by Boydk, link
In order to try lifting the heater ground I will have to cut a couple of tracks on the pcb since both grounds are connected. I do not think it can make a difference as I also fed the heaters with pure dc / battery but I'll try it anyway and report here in case it has an effect.
What do you think would be a realistic output ripple with this preamp?
thank you
In order to try lifting the heater ground I will have to cut a couple of tracks on the pcb since both grounds are connected. I do not think it can make a difference as I also fed the heaters with pure dc / battery but I'll try it anyway and report here in case it has an effect.
What do you think would be a realistic output ripple with this preamp?
thank you
I build the phono preamp, see post #71. The heater ground was connected to supply gound to minimize the number of cables from power supply case to preamp case. I did not measure the ripple at @50Hz, but there is no audible hum on my system/setup on normal levels. When I turn my line preamp to maximum volume there is very little hum with my ear close to the speaker (95dB sensitivity).
A few suggestion to minimize the hum:
1. Twist input cables from preamp input socket to PCB (very important)
2. Try different connection of output socket ground (on PCB or on GND binding post)
3. On bottom for PCB there is a middle ground trace, try to solder a solid copper wire on top of the trace (see if it lowers the hum levels).
1 & 2. There is no chassis, I measure directly on PCB pins with input shorted
3. good idea, will try this in order to further reduce resistance of ground tracks
Hi FF......
This is awsome. That´s a pretty accurate riaa curve (I know both records very well). Fantastic sound from the SA. I´ve had the EV, PTG and PTG-II but never heard the SA before. When I finally get it (MiniMe) built, I wonder how it will match my cartridge. Was so lucky to get a dirt cheap offer for an Ikeda-9TS. After a week it outperforms my Sumiko Palo Santos..... Scary
After listening to your examples, I need to find the time to finish a piece of MiniMe Not that I´m not happy with my Papa X-Ono Clone, but these files from you sound really, really great.
Thanks a lot for doing the work
This is awsome. That´s a pretty accurate riaa curve (I know both records very well). Fantastic sound from the SA. I´ve had the EV, PTG and PTG-II but never heard the SA before. When I finally get it (MiniMe) built, I wonder how it will match my cartridge. Was so lucky to get a dirt cheap offer for an Ikeda-9TS. After a week it outperforms my Sumiko Palo Santos..... Scary
After listening to your examples, I need to find the time to finish a piece of MiniMe
Not that I´m not happy with my Papa X-Ono Clone, but these files from you sound really, really great.Thanks a lot for doing the work
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a quick update on the hum issue I noticed. My initial assumption that being @50Hz it was due to interference from power transformer was valid, despite it being almost half meter away. High amplification takes its toll
I temporarily put the pcb inside an earthed aluminum chassis and ripple at the output was reduced to less than 1mV
thank you Koifarm and Boydk for the very nice circuit and pcb!
I temporarily put the pcb inside an earthed aluminum chassis and ripple at the output was reduced to less than 1mV
thank you Koifarm and Boydk for the very nice circuit and pcb!