Hi everyone,
look what I found....the unison research s8!
unison audio s8 845 single ended tube amplifier,octal 2a3,el34,ecc82,ecc88,kt88,300b,845 direct heated triode,mkp, ...
So..I posted the schematic. Now, is there anybody out there that can help me build this sweet jewel?
I'm not an expert in elecronics, so I'll build it with my uncle, but I need some help on finding all the needed pieces.
I was told by someone who knows a lot about tube amps to use a 5687 alimented at around 550v to drive the 845.
Ervin
ps. could please someone who knows how to do it rewrite the schematics on the computer?
look what I found....the unison research s8!
unison audio s8 845 single ended tube amplifier,octal 2a3,el34,ecc82,ecc88,kt88,300b,845 direct heated triode,mkp, ...
So..I posted the schematic. Now, is there anybody out there that can help me build this sweet jewel?
I'm not an expert in elecronics, so I'll build it with my uncle, but I need some help on finding all the needed pieces.
I was told by someone who knows a lot about tube amps to use a 5687 alimented at around 550v to drive the 845.
Ervin
ps. could please someone who knows how to do it rewrite the schematics on the computer?
Last edited by a moderator:
.for 845 or 211 you can use best driver but mor $.diy is not copy of unison tube ampdiy = best sound
You mean I can spend better my money on investing them on a better diy 845 amp? Any suggestion?
ps. Don't you like the s8 schemtic? Do you think there is something that can be improved?
Something could indeed be improved; The s8 does not allow class A2 operation due to the AC signal coupling of the output tube's grid.
Take a look at the schematics from Tubelab for the 845, you can find the schematics over here: 845SE
In his amplifier he drives the output tube's grid DC coupled with a mosfet. This arrangement allows for grid current to flow, which in turn allows operation into higher power levels (read the article for more information, it's quite a good read
).Now this is where diy comes into play; If for example you like the idea of the ability to operate the output tube in class A2 mode but you don't like the pre descending driver stages, then change the driver stage. Or if you really like the amplifier layout but fear for mosfets affecting the sound, then change the amplifier to suit your needs and replace the mosfets with tubes capable of doing the same job.
Last edited:
In between the u.r. smart845 and the u.r. s8, what would you choose?
Here there are the smart 845 schematics:
http://www.diyaudio.com/forums/tubes-valves/191357-unison-research-smart-845-a.html
Ervin
Here there are the smart 845 schematics:
http://www.diyaudio.com/forums/tubes-valves/191357-unison-research-smart-845-a.html
Ervin
Personally I would build neither of them, but that is because I am on the DC coupled / feedback-less road.
If I would have to choose between these two designs only, then I would prefer the S8 because of it's simplicity and my preference for the grounded cathode stages above SRPP stages.
Both designs have the drawback of only operating in class A1 which limits the output power and add's grid-blocking distortion when being overdriven. The design from Tubelab overcomes these problems and seems logical, effective and simple.
If I would build an amplifier with 845 tubes the Tubelab's design would be my first choice. However, I do not see myself building a 845 amp in the near future since I am happily on a different road
Last edited:
>> Personally I would build neither of them, but that is because I am on the DC coupled / feedback-less road.
After a day spent reading I do agree with you, this is why I'm looking for the simply 845 schematics now, since it is a no feedback amplifier.
I do really appreciate your suggestion about the tubelab's 845 amp lechuk, but in my mind goes on only one thing: build an unison research amp, build an unison research amp, build an unison research amp! Don't ask me why please, I don't know the answer!
Any idea on where to find the schematic of the simply 845?
Ervin.
After a day spent reading I do agree with you, this is why I'm looking for the simply 845 schematics now, since it is a no feedback amplifier.
I do really appreciate your suggestion about the tubelab's 845 amp lechuk, but in my mind goes on only one thing: build an unison research amp, build an unison research amp, build an unison research amp!
Don't ask me why please, I don't know the answer!Any idea on where to find the schematic of the simply 845?
Ervin.
>> Personally I would build neither of them, but that is because I am on the DC coupled / feedback-less road.
After a day spent reading I do agree with you, this is why I'm looking for the simply 845 schematics now, since it is a no feedback amplifier.
I do really appreciate your suggestion about the tubelab's 845 amp lechuk, but in my mind goes on only one thing: build an unison research amp, build an unison research amp, build an unison research amp!
Any idea on where to find the schematic of the simply 845?
Ervin.
You could simply play around with the feedback of the U.R. circuits, or leave the feedback out.
If you have the resources; why not build several circuits and choose the one that sound best in your ears? I build my amplifiers initially on a wooden board so I can experiment with them and build the final amplifier based on what sounds best in my ears.
The expensive components for the different circuits are similar, you could use the same power transformer, output transformer and output tube for these circuits. The less expensive parts like resistors, caps and small tubes are not to expensive to get, and you could sell some of them off after your final build.
You could concern it to be a little bit more DIY than simply building an existing (and probably well proven) circuit, but with it's own (read commercial) limitations. If you experiment yourself you can end up with a much better amplifier, and you always have the possibility to revert to an existing circuit if it doesn't work out as well as you've hoped.
Have you ever listened to a U.R. 845 tube amp, or a 845 tube in general, before? It's a big tube with big voltages, not really a tube I would recommend to an un-experienced builder because of the risks involved.
- edit -
Almost overlooked your question
From the appearance of the Simply 845 I would guess the circuit is not that much different from the Smart 845. While searching I also found out that this amplifier only put's out a merely 24 watt's per channel. Getting back to the design from Tubelab, he get's > 40 watt's per channel, and claims more than 50 watt's would be possible as well:
Last edited:
I must be sincere, never listened to a 845 tube amp, but I'd really like one, and this is why I want to build it.
Who would build it is my uncle, not me. I do not have enough experience to play with this kind of voltages, but he does (physic university teacher, and time ago he loved 'playing' with tube radios and tvs, but it's been a while since then..).
I'll think about what to do, but after all that good reviews about the unison research simply 845 I would really like to built it.
Unfortunatly is not produced anymore.. Maybe I can ask to unison research if is there any possibility of listening to some of the products they have. They are here near my house (only 35km), so it's not a matter of distance!
Who would build it is my uncle, not me. I do not have enough experience to play with this kind of voltages, but he does (physic university teacher, and time ago he loved 'playing' with tube radios and tvs, but it's been a while since then..).
I'll think about what to do, but after all that good reviews about the unison research simply 845 I would really like to built it.
Unfortunatly is not produced anymore.. Maybe I can ask to unison research if is there any possibility of listening to some of the products they have. They are here near my house (only 35km), so it's not a matter of distance!
Last edited: