WTD : Tube Buffer

[Bigman80]

That's great news. Patience visit paying off then.

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[Stryder5]

That's great news. Patience visit paying off then.

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Can we have a small Midlands meet at Alan's to listen

[Firebottle]

Yes bring it on.

I'll be experimenting with the output impedance later on.

[Bigman80]

Can we have a small Midlands meet at Alan's to listen

Yes bring it on.

I'll be experimenting with the output impedance later on.

sounds good !

[Stryder5]

sounds good !

Just let me know when, I'll be there.......

[Lawrence001]

Had it plumbed into the system and it is 'outstanding' to nick Oliver's description.

Very difficult to tell it was 'in system', just played a few LP sides, only one small problem of a little hum in the background.
This has now been cured by the addition of one extra electrolytic cap in the PSU section.

There is a high output impedance of 3.4 Kohm, but with short output leads and a high(ish) input impedance of the following amplifier this presents no problems.

I will be investigating a little mod to give a lower output impedance in due course.

I don't know exactly what the technical definition of a buffer is but do you think this kit should be sold as such on eBay with that output impedance?

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[Firebottle]

It's being sold as a tube pre-amp rather than as a buffer.

[nthall]

How much gain does it have? I know buffers technically aren't supposed to have any, but with tubes I've never seen any benefit of using them strictly for impedance matching.

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[Firebottle]

It's about 15dB Nathan.

[Barry]

I don't know exactly what the technical definition of a buffer is but do you think this kit should be sold as such on eBay with that output impedance?

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It's a bit high for a cathode follower, but as Alan says it will be OK with leads of a reasonable length. Assuming the load impedance is at least 50K, then setting the low-pass -3dB point at 30,000kHz, one could use cables having a typical capacitance of 100pF/m as long as 16m.