Valve info

[StephenRutledge]

some interesting info about valves
http://www.jacmusic.com/KT88/kt88.htm

[teddy07x]

very interesting indeed. Steve should chime in and enlighten us on this subject.

What I'm wondering is, is tube build quality and sound quality parallel?

[StephenRutledge]

I'd love to get my hands on those old KT66s and find out 8)

[MKB]

What I'm wondering is, is tube build quality and sound quality parallel?

Usually it is. The tubes regarded as superior tonewise were made by US and UK suppliers back when tubes were the primary signal technology, and before the environmental laws stopped the use of many noxious chemicals and materials needed for good manufacture. I've heard the high quality metals needed for vacuum tube plates haven't been available for many years also. I haven't heard of many good sounding NOS tubes that didn't last a long time as well.

[teddy07x]

What I'm wondering is, is tube build quality and sound quality parallel?

Usually it is. The tubes regarded as superior tonewise were made by US and UK suppliers back when tubes were the primary signal technology, and before the environmental laws stopped the use of many noxious chemicals and materials needed for good manufacture. I've heard the high quality metals needed for vacuum tube plates haven't been available for many years also. I haven't heard of many good sounding NOS tubes that didn't last a long time as well.

do you think investing in expensive NOS tubes will improve sound? :)

[MKB]

do you think investing in expensive NOS tubes will improve sound? :)

The consensus on this seems to be yes, but the question is by how much and does the investment make sense to you. The VM sounds excellent with the stock tubes, and there are many threads on this board where individuals have tried NOS tubes with success. I personally have tried only one replacement, put a NOS RCA 7025 in V4, and I think it helped the tone quite a bit (the distortion is clearer and more detailed). Steve said in an earlier post ( http://vintagemodern.informe.com/viewtopic.php?t=2275 ) that there was a difference using NOS GEC KT66's in place of the stock ones, but that is mighty big money to run that test.

Something else to keep in mind is that Steve probably built and voiced the VM to use the currently available tubes, so there is a possibility that a NOS tube might make the amp sound worse. I haven't experienced this first-hand in a VM, but have heard this in other amps.

As a good cheap source for old stock tubes for experimenting, I'd suggest you look for old tube equipment at hamfests and local surplus shops. As an example, old Dynaco tube stereos used Telefunken smooth plate ECC83's as private branded preamp tubes, and Mullard EL34's as power tubes. Most any old equipment will have good tubes in them. I found an old power supply at a hamfest (for $10) with six pristine Telefunken ECC83's in it. I replaced the Teles with Chinese 12AX7's, and the power supply works perfectly. And the tubes indeed sound good. Another source is local engineering colleges, they often have donated equipment lying around with good old tubes in them.

[teddy07x]

do you think investing in expensive NOS tubes will improve sound? :)

The consensus on this seems to be yes, but the question is by how much and does the investment make sense to you. The VM sounds excellent with the stock tubes, and there are many threads on this board where individuals have tried NOS tubes with success. I personally have tried only one replacement, put a NOS RCA 7025 in V4, and I think it helped the tone quite a bit (the distortion is clearer and more detailed). Steve said in an earlier post ( http://vintagemodern.informe.com/viewtopic.php?t=2275 ) that there was a difference using NOS GEC KT66's in place of the stock ones, but that is mighty big money to run that test.

Something else to keep in mind is that Steve probably built and voiced the VM to use the currently available tubes, so there is a possibility that a NOS tube might make the amp sound worse. I haven't experienced this first-hand in a VM, but have heard this in other amps.

As a good cheap source for old stock tubes for experimenting, I'd suggest you look for old tube equipment at hamfests and local surplus shops. As an example, old Dynaco tube stereos used Telefunken smooth plate ECC83's as private branded preamp tubes, and Mullard EL34's as power tubes. Most any old equipment will have good tubes in them. I found an old power supply at a hamfest (for $10) with six pristine Telefunken ECC83's in it. I replaced the Teles with Chinese 12AX7's, and the power supply works perfectly. And the tubes indeed sound good. Another source is local engineering colleges, they often have donated equipment lying around with good old tubes in them.

hmm....

well Steve didn't really elaborate on that too much. :)

I'm tempted to try it.... but 600 bucks for a pair of GEC KT66 is some money! :)