hello everyone
I have an unknown original amp(no schematic) with a double push of 7868.
these lamps are at the end of life and I have in stock 2x4 6p41s.
I would like to know if any of you have already made swap 7868 / 6p41s and if he can give me some ideas for implementation and modification.
thank you
I have an unknown original amp(no schematic) with a double push of 7868.
these lamps are at the end of life and I have in stock 2x4 6p41s.
I would like to know if any of you have already made swap 7868 / 6p41s and if he can give me some ideas for implementation and modification.
thank you
This is an interesting thread.
I just recently picked up a Rowe (juke box) amp with very knackered 7868's.
Ok so simple solution is to get a set of 6P14's. When they arrived I put them on the curve tracer and couldn't quite believe the phenomenal performance, thinking this will need much more bias than the standard 14 Volts. Being a bit busy I put it to one side but made a mental note that probably a conversion to auto bias is most likely the optimum solution.
I just recently picked up a Rowe (juke box) amp with very knackered 7868's.
Ok so simple solution is to get a set of 6P14's. When they arrived I put them on the curve tracer and couldn't quite believe the phenomenal performance, thinking this will need much more bias than the standard 14 Volts. Being a bit busy I put it to one side but made a mental note that probably a conversion to auto bias is most likely the optimum solution.
Already discussed.
6P41S is totally different tube, even though looks kind of similar. Since your amp can provide higher swing, you can try 6L6 tubes. In such case it may work, with less feedback as the result.
7868 tubes - replace with 6L6's?
6P41S is totally different tube, even though looks kind of similar. Since your amp can provide higher swing, you can try 6L6 tubes. In such case it may work, with less feedback as the result.
7868 tubes - replace with 6L6's?
Why?ok thank's
I will opt for a quad of 7591 and change the sockets.
7868 – 1 Quartett selektierte Electro-Harmonix Rohren-Tubes matched quad (~7591) | eBay
Brand New Electro-Harmonix 7868 Plate Current Matched Quad (4) Vacuum Tubes | eBay
Yes, OS 7868s are very scarce. However, (repeat) New Sensor is currently producing 7868s.
Find an EU dealer that carries New Sensor's product. You should not have to pay the price New Sensor shows. The "blurb" that follows below is taken from the site of excellent U.S. dealer Jim McShane.
Find an EU dealer that carries New Sensor's product. You should not have to pay the price New Sensor shows. The "blurb" that follows below is taken from the site of excellent U.S. dealer Jim McShane.
7868 Electro Harmonix, same size bottles as NOS, great to have new production tubes! $29.50 ea., $59.50/pair,
$119.50/quad. Properly matched by me personally at 425 volts, not just "distributor" matched! Note - the pins on the
EH tubes are larger than old stock, and require very careful installation. After the first time they are installed
it's much easier to do.
why persist in wanting to keep the 7868 while the 7591 is exactly the same with a different broaching.
the 7868 will not be manufactured long, it has only to see the number of adapter sold on the net to convert magnoval support in octal .deja on the hitone, in the 60 ", he had changed the 7868 for the 7591 and I do not think it's the only ones who did it.
to finish, actually I find EH in Europe, but twice the price of usa ...
the 7868 will not be manufactured long, it has only to see the number of adapter sold on the net to convert magnoval support in octal .deja on the hitone, in the 60 ", he had changed the 7868 for the 7591 and I do not think it's the only ones who did it.
to finish, actually I find EH in Europe, but twice the price of usa ...
7868 Electro Harmonix, same size bottles as NOS, great to have new production tubes! $29.50 ea., $59.50/pair,
$119.50/quad. Properly matched by me personally at 425 volts, not just "distributor" matched! Note - the pins on the
EH tubes are larger than old stock, and require very careful installation. After the first time they are installed
it's much easier to do.
In other words: These EH 7868 are Magnovals rather than Novars?
Best regards!
In other words: These EH 7868 are Magnovals rather than Novars?
That's correct. I suspect that New Sensor could not conveniently source Novar bases, but Magnoval bases were available. The pin circle is the same, but Magnoval pins are bigger than Novar pins. Given the "tired" state of many units' sockets, the fatter pins can be a blessing. Be warned that once current production 7868s are used, going back to OS tubes, without replacing sockets, is not an option. Given the very, very, poor availability of OS 7868s, the socket issue is theoretical, not practical.
why persist in wanting to keep the 7868 while the 7591 is exactly the same with a different broaching.
New Sensor will make the tubes, as long as a market exits. There are some units where installing Octal sockets and 7591s will not work, due to space considerations. Profit is a very powerful motive.
Well, the EH 7868s really require a magnoval socket. At least, with the 7591A, you have 3 choices for vendors, and they aren't choosy regarding sockets. I've been getting good results with the EH parts. I intend to try the 6P41s some time to see what I can squeeze out of them. Too bad the documentation on that tube is so poor.
http://forum.elektor.com/download/file.php?id=2702423Are there available any datasheets for these 6P41S?
Best regards!
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