Good morning everyone
I have a cheap tube buffer using 6J1 tubes (one per channel).
I am quite liking what i am hearing.
I would like to try something better than the stock anonymous tubes. But i wonder if a better tube can really improve the sound leaving all other buffer parts unchanged.
Thanks a lot indeed.
I have a cheap tube buffer using 6J1 tubes (one per channel).
I am quite liking what i am hearing.
I would like to try something better than the stock anonymous tubes. But i wonder if a better tube can really improve the sound leaving all other buffer parts unchanged.
Thanks a lot indeed.
Hi ! sorry but i cannot source the schematic that i would love to get
Anyway ... this is the unit
FX Audio TUBE-01 6J1 Tube Buffer HIFI Pre Amplifier Sliver: Amazon.it: Elettronica
it looks pretty well conceived
I see a dc-dc converter to generate the plate voltage ?
I have got an improvement using and Apple power supply 12VDC over the stock one
I will be trying a 12V sla battery pretty soon even if not the handiest solution around. In this way i will get a complete isolation from the mains.
I am very curious to listen.
But a better tube should not do damage anyway
Anyway ... this is the unit
FX Audio TUBE-01 6J1 Tube Buffer HIFI Pre Amplifier Sliver: Amazon.it: Elettronica
it looks pretty well conceived
I see a dc-dc converter to generate the plate voltage ?
I have got an improvement using and Apple power supply 12VDC over the stock one
I will be trying a 12V sla battery pretty soon even if not the handiest solution around. In this way i will get a complete isolation from the mains.
I am very curious to listen.
But a better tube should not do damage anyway
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Hi ! thank you very much indeed for your kind and valuable advice
I am quite lost with all these equivalent tubes ... looking for EF95 tubes i found these looking very serious
Siemens 5654W EF95 6AK5 valvola originale in scatola New old stock-abbinato COPPIA (V35) | eBay
thanks a lot and this is very interesting. Can this be considered a general rule ?
Anyway ... please let me described my dream project.
Being quite impressed by the flavour that this little unit gives to the sound i would like more of it.
More being a buffer but with a tube that i deeply love ... the 12bh7
A very powerful tube that i understand is not that common but used in some so called high end tube amps as a driver
What i like of this cheap design is the power supply solution adopted.
I really would like to use a single good quality 12VDC and a dc-dc step-up converter to generate the plate voltage. I find this solution elegant.
I really do not know if the 12bh7 can work fine as a buffer also at lower voltage
Thanks a lot again.
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Thanks a lot. Done
Please let me elaborate again a little more. I am following the thread about a solid state buffer designed by Nelson Pass and members are amazed by its performance. So i guess that in general an active buffer can work as a very nice line stage. I like the tone of tubes But looking at these little tubes ... i get a feeling of weakness. Also the pins do not enter smoothly in their sockets
I really would like to try a 12bh7 ... my dream buffer.
I wonder if anyone has experience using switching power supplies with tubes
I see that high voltage output boost converter are available
DC-DC 8~32V to 45~390V High Voltage Boost Converter A4R6 J7E1 Step-up R6P3 | eBay
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I'm not sure about what you are looking for. Using 2 x 12BH7 instead of 2 x 6J1 in your buffer would require an adapter to begin with. Running the two triode sections in a 12BH7 parallel could be too much for the B+ power supply in your buffer (too much current draw).
I doubt it that the buffer would sound 'less weak' with 12BH7's. The amplification factor of the 12BH7 is 16.5, while that of the 6J1 is about 28 in triode mode (see the Ericsson datasheet for the 5591, a longlife version of the 6AK5/6J1).
Ofcourse the actual amplification depends on more parameters (B+ voltage, plate load, etc.) but since we don't have a schematic of your buffer, it's hard to get more precise.
Maybe it's best to (first) try what azazello suggested, allthough I doubt that a 6Ж5П will give more gain, because as far as I could make up from the Tesla datasheet of the 6F36 (an equivalent of the 6Ж5П), the amplifcation factor is about 30 in triode mode, so practicaly the same as 6J1.
I doubt it that the buffer would sound 'less weak' with 12BH7's. The amplification factor of the 12BH7 is 16.5, while that of the 6J1 is about 28 in triode mode (see the Ericsson datasheet for the 5591, a longlife version of the 6AK5/6J1).
Ofcourse the actual amplification depends on more parameters (B+ voltage, plate load, etc.) but since we don't have a schematic of your buffer, it's hard to get more precise.
Maybe it's best to (first) try what azazello suggested, allthough I doubt that a 6Ж5П will give more gain, because as far as I could make up from the Tesla datasheet of the 6F36 (an equivalent of the 6Ж5П), the amplifcation factor is about 30 in triode mode, so practicaly the same as 6J1.
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Hi ! thanks a lot for the very kind and helpful advice. Sorry i have not been clear. I am trying to put information and my own listening experience together
First i like what this tiny tube buffer does to the sound a lot. The sound is more relaxed especially with digital sounds ... i like this.
Then reading another thread about a minimalist solid state buffer one guy was liking it better than his very expensive line stage
So the idea is to try to put together a tube buffer that can drive almost any common power amp stage (let aside those with a very low Z input)
And at the same time i am trying to understand if a smps for the plate voltage can be a valid option. These dc-dc boost converters are almost everywhere and sold for some USD ... they are tempting
The 12bh7 would be of course a complete new idea ... i am not trying to mod this unit because i am sure i would destroy it. For the 12bh7 a new unit should be built. Maybe using just one tube for both channels ?
actually i hoped just that
i read that the 12bh7 is a very powerful tube used as a driver for output stages ... clearly i was wrong i think i can open it and take some pics but only in the weekend ... i will try that and keep the board out of the case for any request
If i find another one used i will buy another ... used should come for no more than 20-25 USD
Yes ! following the advice i bought these ... they will take some time to reach me
+ NUOVI 12 PC. x 6J5P (6Ж5П) 6Z5P come 6AH6 6F36 USSR Pentode Tubos NOS | eBay
if i understand correctly they should be 12 tubes ? from Ukraine ?
that is fine because i am sure i will break some during the testing
As i said above i have problems putting them into the sockets I wonder if i can use some kind of conductive liquid that helps the insertion
I am scared by the idea that a tube could break when i force it with the hand
Thanks a lot again
Nice, adason.
If the buffer of TS is like the buffer of adason (so a cathode follower), than the amplification is close to 1 (one). Tube rolling in such a buffer will hardly have an effect on how 'weak/strong' the buffer will sound, because the gain will also be close to 1 (one) with other tube types (that's what cathode followers do). But there are people who hear differences in sound quality between different tube types, so you could still try tube rolling.
Question for TS: Can you see on the circuit board if there is a load resistor between the pins for the anode/g2 and B+? And if you see one, what is its value (color coding)? Or can you post some close-up pictures of your buffer? Maybe we can make out the schematic around the 6J1's.
If the buffer of TS is like the buffer of adason (so a cathode follower), than the amplification is close to 1 (one). Tube rolling in such a buffer will hardly have an effect on how 'weak/strong' the buffer will sound, because the gain will also be close to 1 (one) with other tube types (that's what cathode followers do). But there are people who hear differences in sound quality between different tube types, so you could still try tube rolling.
Question for TS: Can you see on the circuit board if there is a load resistor between the pins for the anode/g2 and B+? And if you see one, what is its value (color coding)? Or can you post some close-up pictures of your buffer? Maybe we can make out the schematic around the 6J1's.
Hi thanks a lot ...this is very difficult for me to do Very
I thought CF were simpler Is this a triode ? it looks different
i had a similar issue once ... i was advised to put a 100-200 ohm resistor at the input between the wiper pin and the input coupling cap
and the noise went away
But it was not a tube preamp it was a solid state one You could try maybe it works also for you
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Ok ... i will try asap ... what i can do to make the tubes insertion easier ? i do not want to force them and break them
Thanks again.
Hi ! sorry but i cannot source the schematic that i would love to get
Anyway ... this is the unit
FX Audio TUBE-01 6J1 Tube Buffer HIFI Pre Amplifier Sliver: Amazon.it: Elettronica
it looks pretty well conceived
I see a dc-dc converter to generate the plate voltage ?
I have got an improvement using and Apple power supply 12VDC over the stock one
I will be trying a 12V sla battery pretty soon even if not the handiest solution around. In this way i will get a complete isolation from the mains.
I am very curious to listen.
But a better tube should not do damage anyway
Those little FX units, and the numerous variations, are not buffers. They are preamps, which have gain.
There is a massive mega-thread about them which will give you all the information you need about using different tubes, power supplies and much more.
Here's a link: FX Audio 6j1 tube preamp - a $31 wonder | Audiokarma Home Audio Stereo Discussion Forums
Hi ! thank you very much indeed for the very helpful advice
To be completely honest i have been intrigued by the dc-dc converter solution
I have never seen one in a tube preamp and i wonder if it could be a valid approach
Ebay is full of these boost converters very unexpensive ... maybe they are also very bad i do not know. But it seems that just one decent 12VDC power supply and one of this converter and voilà a power supply for a preamp is done
Very convenient
However i will study the link ... thanks a lot again
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Tubes do not create power, but handle/throttle what is being fed them.
In a high power amplifier a 12BH7 will stand high supply voltage, pass important current, output high power (for a preamp/driver tube that is) signal to drive hungry power tube grids, where a couple tiny 6J1 would *explode*.
But putting a 12BH7 in your tiny battery fed board is like slapping Ferrari Formula 1 racing tyres on a Topolino
Good morning ! perfect ! your words confirm my best feelings about the 12bh7 that is what i am heading to. It will take some time but i will do it ... a 12bh7 buffer. That is sure. I just hope not to get electrocuted in the process
Nice car !
it was conceived and built in my own town Torino Anyway ... i believe that no one in their right mind can think of doing this. And in fact I thought about it for a long time ... seriously I will try to explain my thinking better.
Starting from the positive listening notes on this small device but also here on the forum on the Nelson Pass B1design, I dismissed some of my prejudices. In particular with respect to buffers. In short, when well done they can sound very well and perform very well the function of line stages when voltage gain is not necessary (my case).
With this premise there are some aspects of this small buffer that do not convince me. Starting with the tubes used. I would much prefer a classic tube, something of which i can find a very good NOS for example.
I especially like the 12bh7 which is the one I would like to use. But nobody considers it. I searched a lot for some buffers in kit but nothing. And I'm wondering if a circuit that works for the 12au7 could also be valid for the 12bh7. For 12au7, buffer circuits are much more common.
Of course i am open to consider any other tube very very good for buffer duties. Possibly one able to provide a great performance also at lower voltages ... i do not like high voltage applications at all.
Then another aspect.
I see that in this small buffer the plate voltage is generated by a dc-dc step-up converter. I really like this solution. I consider it elegant.
My idea is to use a quality laptop power supply. Based on personal experiences I can say that the branded ones (Lenovo, Dell, Toshiba, etc.) are built very very well. They usually put out about 20V and 3 to 6 Amps.
This power available is plenty for any preamp design.
Then i would use a very basic regulator to get the 12V for the filament and a step-up converter to get the plate voltage. Very elegant ... very simple.
By eye, getting my hands on this device so small in my opinion means destroying it.
But it made me realize that a buffer can give an extremely musical and pleasant tone to the sound. Even if we have 100% negative feedback.
Now the next step is to find a buffer kit I am not able to start from the scratch ... for now.
If you have any suggestion ...
Thanks again and best regards, gino
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Hi ! thanks a lot ! for now i have already ordered a stock of 6Ж1П from Ukraine.
Anyway i wonder if the 6Ж38П is completely equivalent electrically to the stock tube. I would not want to stress the unit.
I see many on ebay ... is there a specific brand/source to look for ?
https://www.ebay.it/sch/i.html?_from=R40&_nkw=6J38P&_sacat=0&rt=nc&LH_BIN=1
prices are very good indeed ... no more than 2USD/each shipping included
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