• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

I need a schematic for a tubed crossover that can cope with 10k load impedance?!?

Micke,
Balanced crossovers are rare creatures, no matter what kind of load you're talking about. However...
You can 'roll your own.' I'd recommend 6DJ8s, as they are capable of much more output current than, say, a 12AX7. Start with a differential, followed by the filter network, and finish with cathode followers. The cathode followers are important because, like an emitter or source follower, they have lower output impedance and more drive capability. You'll need to go into this having a clear idea of what crossover slopes and frequencies you will need.
There are some tube crossovers (none balanced, mind you) at http://www.tubecad.com. There are other tube crossovers out there, but again, none balanced that I can recall. Hit the links section here in DIY and fan out from there.
It is also possible, if you are building from scratch, to work the crossover slope into the amplifier itself. There are several ways to do this, but it's best to keep it flexible in case you decide to change speakers (or amps) later.

Grey
 

ThorstenL

Previously: Kuei Yang Wang
2002-11-10 5:35 pm
www.facebook.com
Konnichiwa,

hifi said:
have anybody done such a design or know any schematic?....preferably a balanced design but that is not required the load of the aleph amp is low 10kohm...but i would like to use a tubed crossover anyway...

The Marchand Tube crossover schematics are in their downloadable manuals. They can be made balanced I/O by using suitable Transformers. By using a 4:1 Line Input transformer and changing the first buffer stage to one that combines a gain of 16 and a buffer stage you can get the whole X-over to work at a higher level.

Then add suitable output transformers with stepdown (S&B, Jensen and Sowter have nice ones in their pro ranges) and use a follower valve with more current (eg ECC82 instead of ECC83 and reduce th cathode resistor in the marchand design by a factor 5 - 6).

That way you have an output that will tolerate 10K load easily and is balanced. Using a 4:1 stepdown you will have a 10K load translated into 160KOhm in the transformers primary.

Sayonara
 

RLRB

Member
2010-01-16 10:12 am
Konnichiwa,



The Marchand Tube crossover schematics are in their downloadable manuals. They can be made balanced I/O by using suitable Transformers. By using a 4:1 Line Input transformer and changing the first buffer stage to one that combines a gain of 16 and a buffer stage you can get the whole X-over to work at a higher level.

Then add suitable output transformers with stepdown (S&B, Jensen and Sowter have nice ones in their pro ranges) and use a follower valve with more current (eg ECC82 instead of ECC83 and reduce th cathode resistor in the marchand design by a factor 5 - 6).

That way you have an output that will tolerate 10K load easily and is balanced. Using a 4:1 stepdown you will have a 10K load translated into 160KOhm in the transformers primary.

Sayonara

Hi Thorsten, I have Oris 150 with AER bd3 and ripoles 4 x bd15. I have pset 2a3 for horns and ss 200w for bass. I use a March and xm26 heavily Duelund modified.
The question. Can I use ecc81 tubes without modifying resistors? Only v4 or all tubes, input buffer, dividers and output bigger. Is better ecc81 than ecc83 for cathode follower. Second question. In order to get xlr inputs I only need a lindahl 1.1 transformer? My player is Dcs and has same voltage in rca and xlr.