Croft Vitale - hiss

[Simon_Nottingham]

Hi,

I've recently acquired a Croft Vitale preamp. It's putting out quite a lot of hiss, it's quite noticeable when there's no music playing and during the quiet bits.

Is there anything that it's most likely to be or would I be best to get in touch with Glenn Croft for a service?

I have no knowledge of its history, so I don't know if he's looked at it before (after making it that is!).

Thanks

simon

[Firebottle]

I have read that it's not the quietest of preamps, can you provide a little more detail?

Can we assume the hiss is when using the phono input? If so what cartridge are you using?

Asking so that the output level can be assessed.
Does it use ECC83 valves or the larger octal valves?

:)

[Yomanze]

How sensitive are your speakers? Hiss is usually down to the noise floor of the component.

[Simon_Nottingham]

The hiss is with all inputs, even when it's on mute. If I turn the preamp off (i.e. just the power amp on) it's silent.

My speakers are JPW AP2s.

I'm not sure on the valves - and I'm not at home this week to check.

[Firebottle]

Simon, is the volume control only turned a small amount to give a good volume. This may be a gain issue, i.e. too much gain in the Croft.

[The Black Adder]

Ah... yes I had some hiss on mine due to too much gain... could be that?

[Simon_Nottingham]

Simon, is the volume control only turned a small amount to give a good volume. This may be a gain issue, i.e. too much gain in the Croft.

It's at any volume - even none.

What does 'too much gain' mean?

[Yomanze]

It's at any volume - even none.

What does 'too much gain' mean?
The hiss is your pre's noise floor for sure. This can be improved with a service from Croft, but not eliminated.

As has been said if it's loud hiss then can be a gain mismatch between pre and power amp.

What is more important is how it sounds at very low volumes - if it is distracting then it's a problem!

[rubber duck]

The hiss is your pre's noise floor for sure. This can be improved with a service from Croft, but not eliminated.

I'm not so sure. I sent both my 25 Basic and 25 to Glenn to change the output impedance because of the hiss and both are now quiet through my 90dB/W speakers. So you may want to contact Glenn to see if he can do this with the Vitale.

[Yomanze]

Sorry what I meant is that there'll always be a little bit of hiss or hum. :)

[DSJR]

If the power amp is too sensitive (leaving speakers aside for a minute), the noise floor of the preamp which is there all the time will be magnified in level before any music is sent down the line. What power amp are you using?

[Simon_Nottingham]

If the power amp is too sensitive (leaving speakers aside for a minute), the noise floor of the preamp which is there all the time will be magnified in level before any music is sent down the line. What power amp are you using?

Right, now that's an explanation I understand!

It's a Quad 405 clone based unit from reelaudio.co.uk with an off board power supply.

[Simon_Nottingham]

Would something like this be a good solution?

Rothwell in-line attenuators (http://www.ekmpowershop16.com/ekmps/shops/rothwellaudio/in-line-attenuators-2-p.asp)

[Simon_Nottingham]

Would something like this be a good solution?

Rothwell in-line attenuators (http://www.ekmpowershop16.com/ekmps/shops/rothwellaudio/in-line-attenuators-2-p.asp)

A pair of the above have sorted it.

Cheers folks.

[Yomanze]

Gain mismatch indeed then glad you sorted it.

[Simon_Nottingham]

Gain mismatch indeed then glad you sorted it.

Yeah, it's absolutely super now. Thanks for the advice folks.