Pre Amp For a 300b

[snodge]

Hi Nigel,

thank you for your kind offer. I will try and get to you in January. PM me with your address and phone number..Rgds David

[bob orbell]

Originally Posted by snodge

Hi the pre/phono that i have been offered is a WAD KLLP 1. I have read mixed reviews...rgds David

Don't bother. Bob

[Desmodromic]

Originally Posted by bob orbell

Don't bother. Bob

Originally Posted by bob orbell

Should we not try to encourage others to go for WD products, after all, this is a forum for such. Bob

[bikerhifinut]

Originally Posted by bob orbell

Don't bother. Bob

if its cheap enough and the case is cosmetically good, you could always tweak up the KLPP1 with an updated board from the current range, or one of your own choosing.
I have a memory of the KLPP1 circuit and its got a couple of features that I personally think let it down, but Noel keywood was using one for a long time that I think He'd modded. Shame you can't write to HFW anymore and ask the question.
And before Bob has a pop, 'Fess up mate, you did the same as me and bunged a Broskie ACF unity gain buffer board in the Pre3 case and a hifi collective remote volume control board for motorised pot. Along with a regulated PSU, however I blew the pass device on mine and while searching around for replacements and knowing what a chew on it is to remove and refit the darned things I reverted to the original PSU3 board, with a couple extra 100uF on the pre and Phono outputs for an extra RC filter. The replacing of the original somewhat ordinary and of unknown history (I bought it used with some wiring faults) HT Capacitors resolved the instability issues I was getting and I find it jolly good now so havent been bothered to repair the regulated board.
My CF differs from Bobs in that I used ECC82/5814 types rather than ECC88 types, its all a matter of taste here, a CF shouldnt put any character (distortion) on a signal in my view and I found I couldnt really tell any difference between a set of cheap as chips Chinese 12AU7 and some NOS exBBC tested Brimars or the Mullards I have lying around. Thats a feature of the design where one half of an identical double triode is used inversely against the other to eliminate distortions etc caused by the valve characteristics (Shortened explanation from broskies explanation).
The WD CF will be a good bit of kit too and you have the option of whether or not to include the active load on the cathodes. A standard "Bootstrapped" cathode follower is a very good circuit with barely measurable distortion.
I also use a tweaked Pre4 circuit in my other preamp, I had a think and a chat with John C at an audiojumble and tried using the new pre4 board with its excellent earthing routes with unbypassed cathode R on the first stage and resistor chosen to get me my desired gain for my amps Didnt fit the interstage pot as I felt that was causing a problem with impedance meaning a high value of coupling cap was needed. It's written up elsewhere, it works and works very well. I do like transformer output preamps when they work properly.
All said and done, if the gain on your existing preamp is in the ball park and I assume its output Z will be fine into whatever the input Z of the 300B is, then use that and decide if its doing the job for you.
Perhaps that doesnt make any money for Matthew and I will say he gives good value and even better service, but I'd give my existing gear a go before chucking money that would buy more records or Cds at my equipment.
Andy

[snodge]

I didn't realise how contentious this subject is!!! Thanks for the advice.

[bob orbell]

Originally Posted by Desmodromic

Agree with you, but WD (WORLD DESIGHN) and WAD (WORLD AUDIO DESIGHN) are NOT the same company, WAD is no longer trading, but WD is. Bob

[bob orbell]

Yes Andy always give a good wright up on things. Now Andy, are you talking about replacing the IXCY on your regulated board or the LD1085 ? if you are, I can see no problems at all to change them, keep in touch. Bob

[Richard]

David, I'd try your Elekit with the amp first as it will cost you nothing. 300BPP is very sensitive 280mV with feedback on and even more so with it off. This means a simple "passive pre" volume pot will be fine for line sources and, indeed, is suggested in the build instructions. That leaves the phono which can be treated separately depending on how serious a source it is for you.

[snodge]

Hi Richard, I will try the elekit. I am listening to a lot of vinyl so that's my main source at the mo. Best David

[Desmodromic]

Definitely try the Elekit with your 300B first.

Is it the TU-8500 version? If so, then I successfully use mine with the Elekit 300B/2A3 power amp and it's very good indeed. I realise that the MM/MC section is possibly not the strongest part of the TU-8500, but at least you'll know where you are starting from.

You can always tinker a bit with the phono section i.e. swap out the OpAmps, which are very easy to do as they are in sockets. Then you could definitely consider replacing capacitors C11/C12, and even C5/C6 can make a difference.

Hope that helps.