Dennis Had Inspire Amps

[Isaacc7]

I can vouch for the 7n7 and 7c5 combo. They sound great in the KT88 Firebottle as well! I would hate to have loctal sockets on the amp though. Having octal sockets allows you to use regular 6v6 and 6sn7. Adapters for the 7n7 and 7c5 are pretty cheap.

[Analog Addict]

Dennis wanted to convey some additional information…

“The 7C5 octal amplifier is specifically designed for the 7C5 beam power 6V6 variant. There are numerous differences other than just the octal bass and straight pin outs. The critical output transformer is specifically designed for the operating impedance of the 7C5. Of course the power transformer and power supply is optimized for the 7C5 as well. A slightly modified dual bias system is incorporated as well.
So if you like the sonic merits of a 6V6 this new 7C5 takes the beam power Pentode to a higher level of sonic realism. I’m gonna price this at a very reasonable level. A price so that everyone can enjoy an Inspire single ended pentode amplifier.”

You heard it here first….

[Isaacc7]

Originally Posted by Analog Addict

Dennis wanted to convey some additional information…

“The 7C5 octal amplifier is specifically designed for the 7C5 beam power 6V6 variant. There are numerous differences other than just the octal bass and straight pin outs. The critical output transformer is specifically designed for the operating impedance of the 7C5. Of course the power transformer and power supply is optimized for the 7C5 as well. A slightly modified dual bias system is incorporated as well.
So if you like the sonic merits of a 6V6 this new 7C5 takes the beam power Pentode to a higher level of sonic realism. I’m gonna price this at a very reasonable level. A price so that everyone can enjoy an Inspire single ended pentode amplifier.”

You heard it here first….

I'm intrigued... I'll bow to Dennis's expertise, I had always been told the 7c5 was a 6v6. I'll say this, the 7c5 sounds great in the KT88 Firebottle even without having the special output transformer. It's exciting to hear that the price will lower.

I'm not sure what, if any, differences there are with different vintages of the 7c5. I think all of them were made by Sylvania regardless of the label. Of course I have been wrong about the 7c5 before lol. I have been using some JAN 7c5 to great effect. I have a pile of 14c5 that are labeled and boxed as RCA tubes. They have a dark grey coating so it's impossible to tell if they are the same tube. I have an amp coming in the fall that will allow me to use either 6v or 12v output tubes so I can put them to the rest then.

There have definitely been different versions of the 7n7 that have pretty much matched Sylvania's evolution of the 6sn7. Tall bottles, short bottles, "chrome domes," etc. They also went from parallel "T" plates to angled plates at some point. Different people argue about the sonic merits of the different versions, not that I would ever do something like that.... lol. There are also some rare 7n7 made by National Union. They have round plates. Almost impossible to find these days. Apparently the 6f8g NU is the same thing and sounds similar. If that's the case they are good tubes indeed!

Interestingly, at least to me, the 14n7 also included the extra support rod that only appeared in the super rare and expensive Sylvania 6sn7w metal base tubes. I don't know if they sound the same since I won't spend the $$$ to compare but the old, tall bottle 14n7 certainly do look like them. For whatever reason the 14n7 is much more difficult to find than the 7n7. It's weird because 12sn7 are everywhere <shrug>.

I wish Dennis would consider using 12v tubes, they are much more economical. My preamplifier ling with the aforementioned amp I'm getting allows me to use either voltage. It's how I can own exotic tubes like the Tungsol round plate tubes. I assume that would require a different line of power transformers though so I understand from a production point of view why that isn't an option.

[Isaacc7]

Originally Posted by Analog Addict

Dennis wanted to convey some additional information…

“The 7C5 octal amplifier is specifically designed for the 7C5 beam power 6V6 variant. There are numerous differences other than just the octal bass and straight pin outs. The critical output transformer is specifically designed for the operating impedance of the 7C5. Of course the power transformer and power supply is optimized for the 7C5 as well. A slightly modified dual bias system is incorporated as well.
So if you like the sonic merits of a 6V6 this new 7C5 takes the beam power Pentode to a higher level of sonic realism. I’m gonna price this at a very reasonable level. A price so that everyone can enjoy an Inspire single ended pentode amplifier.”

You heard it here first….

I'm also intrigued by what is meant by a dual bias system. And does "slightly modified" imply that a similar system is used in other amps in the line? Is that part of the secret sauce that allows so much tube rolling?

[Isaacc7]

Not to be annoying but I am curious about the numerous differences between the 7c5 and 6v6. According to Sylvania https://frank.pocnet.net/sheets/201/2/2C50.pdf they are identical. Is this one of those situations where on paper things are supposed to be one way but in reality they are different? I ask because I want to make sure I don't screw something up when I manually bias them in my other amp. Thanks.

[PioneerHip]

Officially part of the club! New (to me) CJ5-P in the house. New member here so I can't post attachments yet. I do have a few questions though. Can you run 6C5 in place of the 6J5 and vice versa in this preamp?

[Analog Addict]

Originally Posted by PioneerHip

Officially part of the club! New (to me) CJ5-P in the house. New member here so I can't post attachments yet. I do have a few questions though. Can you run 6C5 in place of the 6J5 and vice versa in this preamp?

Yes. The "CJ5" name is a takeoff on 6C5/6J5 tubes it can use...

[Masterlu]

PioneerHip… Welcome to AA!

[Isaacc7]

Originally Posted by PioneerHip

Officially part of the club! New (to me) CJ5-P in the house. New member here so I can't post attachments yet. I do have a few questions though. Can you run 6C5 in place of the 6J5 and vice versa in this preamp?

I don’t have that preamp but I have recently discovered the joy of using single triodes instead of dual. My preamp uses a pair of 6/12sn7 so with an adapter I can use 2 6/12j5 per side. I had heard that splitting the triodes can have a sonic benefit but really the only reason I tried it is because I already had a bunch of those tubes sitting around.

I have tried 12j5gt Sylvania round plates, JAN Tungsol., and RCA. The Sylvania were impressive, very open and clear but they had a lot more high frequency energy than some other tubes. Combining them with the right amp tubes is really rewarding. I have only listened to the Tungsol briefly but they struck me as a stereotypical “tubey” sound warm and with flabbier bass. Didn’t like the RCA at all, I got zero bass with them.

Right now I am using a quad of Radiotron 6j5gt and they are great. Clear, open sound with solid bass and natural timbres.

Unfortunately the Firebottle is just a bit too cramped to allow the 2x 6j5 adapter. Probably a blessing actually, the blast thing I need is another whole range of tubes to try in the amp lol. 6j5 and 6c5 tubes are still plenty cheap. I’ve even heard the super cheap metal versions are really good. Let us know what you try and what you think.

[cgn-dt-n]

Originally Posted by PioneerHip

Officially part of the club! New (to me) CJ5-P in the house. New member here so I can't post attachments yet. I do have a few questions though. Can you run 6C5 in place of the 6J5 and vice versa in this preamp?

Hi

you can use as a buffer 6c5, 6j5 or 76 with adapter, Dennis gave me his ok for that.

I have tried a lot of 6c5 and had with most of them problems.

The Ultron 6c5 is very good and inexpensive.

6j5 I found better, Zenith 6c5 G and Fivre 6c5 GT are my favorites.

76 was no improvement for me.

In the driver stage I found the 6J5 much better than the 6c5