Difference between CK6528 and 6528A ?

[webercarbmann]

Hi again

Iàm a bit confused. I thought these tubes were rather sought after for Audio applications. Are they not? I not what is the problem with them?


Thanks again


Peter

[SY]

what is the problem with them?

The same problem there is with rich guys willing to give me money- there just aren't enough of them.

[webercarbmann]

Hi again.

Thanks for replying SY.

OK - lets say that I am the ritch guy who has 25 of these - what is the going rato for them? I have seen prices og 50 -85 USD on the web - but that was the A version. What brand is the beast.

The fact that they are limited in supply does make them unrealistic for commercial use - not for DIY/costum use.

I am still not sure if I should by all i can get of these or let them go?

Thanks again

[fdegrove]

Hi,

I am still not sure if I should by all i can get of these or let them go?

That pretty much depends on whether or not you plan to build something with or not and I'd still consider that "unrealistic".

As an investment you'd really need to find a desperate customer as the 6C33-C is a real cheap alternative and other than some industrial applications (transmitters) I really don't know many people using this type.

What brand is the beast.

666?

Cheers,

[SY]

I haven't bought them in a while, so I can't really comment on price. AFAIK, they were all made by the same company, so the branding is merely decoration.

[fdegrove]

Hi,

Penta Labs is selling them for 85.20$ which is certainly not excessive given the industrial application and warranty that comes with it.

Mind you, these could very well be made in China as some of the 6336(A)s I've come across.
Not necessarily a bad thing but I'd still prefer the Raytheons for audio useage.

Cheers,

[Peleus]

I got two 6528 recently. Well! They are pretty great, arn't they!

I plan to build a single tube amp, cause I'd got a DAC with quite high output level, nearly 5V rms!

The only problem is the OPT. One guy told me that the OPT need 200R, not 2K or 1K. Gee! Where can I got that kind OPT? He said the plate resistence of 6528 is 80R, but the resistence I calculated, according to datasheet, is about 200R. Am I wrong?

[tubetvr]

He said the plate resistence of 6528 is 80R, but the resistence I calculated, according to datasheet, is about 200R. Am I wrong?

No, not really, the plate resistance according to this data sheet http://www.mif.pg.gda.pl/homepages/f...115/6/6528.pdf is 245ohm but this is for one section so for 2 sections in parallell it should be ~125ohm, probably a suitable load impedance could be ~500ohm or more maybe up to 1kohm depending on if you want to have max power or min distorsion.

BTW, 6C33C have a plate resistance of 80ohm and seems to be performing best with a load impedance of 600ohm, maybe he mixed up 6528 and 6C33C. Morgan Jones have described a SE amp with 6528 in his book if I remember correctly, check what impeadnce he is using.

Regards Hans

[Peleus]

Thanks! Tubetvr.

I remember that the plate resistence is not a fixed value.

Is it different according to the different working point? For example, using differnet B+ and plate current, then got different value of plate resistence.

Am I right?

[tubetvr]

Is it different according to the different working point? For example, using differnet B+ and plate current, then got different value of plate resistence.

Yes, it varies with operating point, Gm increases at higher current so Ri is reduced, u is relatively more constant

Regards Hans