Hello

[Paul Stoneman]

Good evening and hello,

I am new to the WD forum although I have been checking it out for quite some time.
I have never posted anything before on any forum or similar but this is one is always friendly and informative.
A small bit of history, I built a WAD 6550 years ago for my brother in-law and he sold it to me about four years ago, since then I have upgraded the power supply but have not gotten around to the rest yet. I sounds too good, I have had Mcintosh equipment in the past a C2200 pre and MC252 amp, both excellent but were sold when I was off work after an operation. That was when I acquired the 6550, I have never felt short changed, it is a stunning and reliable integrated amp.
I was fortunate enough a few weeks ago to borrow a WD pre3 and PSU from a good friend and have spoken to Matthew about buying one hopefully later this month, I will convert the 6550 to an amp instead of an integrated.
Anyway enough of my ramblings, thank you all for keeping this hobby and the WAD and WD's alive and kicking.

[bob orbell]

Hello and welcome to the forum Paul, it is a great shame that more new members don't respond with a simple hello. I too started with a KAT 6550, moved on to a WA 88, my good friend now has the 6550 and a Pre III plus Phono III, he also like's it a lot, I hope that we (as a forum) can be of help to you in if you have any problems with your kit. BOB

[Richard]

Morning Bob and welcome Paul! We know what you mean (I think ) Bob
Love 6550's, still got a couple of quads waiting to go in something sometime...
I've only heard Kit6550 as an integrated, a big smooth natural sound, and I can imagine Pre3 would add an extra level of quality to it

[colin.hepburn]

Welcome to WD Paul
I see you are already in safe Hands with bob and Richard

[Paul Stoneman]

Thank you gentlemen.
Yes Richard, when I tried my friends Pre3 (standard trim) with the KIT 6550 a few weeks ago there was a little more push to the music if that makes sense. I am hoping that with the switch bypassed and volume pot replaced with a 47KOhm resistor in each leg, if that is correct, it will improve again. I will get the phone stage when funds allow, the records have not had a spin for over a year.
Take care.

[bob orbell]

Hi Paul, if you are going to remove the volume pot and input selectors and turn the amp. into a power amp., my circuit diagram shows, from phono input socket, screen to earth, centre pin to junction of R9/10 & R7/8 (3k3 & 100k) respectively, the other end of R9/10 to Grid 1 pin 2 of ECF 80, and other end of R7/8 to earth. You could keep the volume pot and use it to adjust the input signal because the Pre III will have too much gain, if you choose the power amp option, just be careful with the volume setting of the Pre III, about the 11 o'clock position of the volume control will over load the amp. BOB

[Richard]

Hi Paul,

Yes better focus and drive are the things I noticed changing to Pre3 from simple passive vol control.

To wire the Kit 6550 just run coax from a pair of RCA sockets; the braids to signal earths and the signals to the nodes of R9/10 and R7/8 as Bob says. I would then replace R7/8 with 100K.

The level may be too high from Pre3 for a good range on the control and there are a variety of ways of lessening the output from Pre3 or decreasing the sensitivity of Kit 6550. The best way I found was to wire the pot of Pre3 as a shunt. I kept about +5dB of gain, so Pre3 will have plenty of level for most power amps, and the volume control stays in a usable range, by using a 20K Alps pot with 47K series resistors before it as per the FAQ.

The choice of pot and series resistors does affect sound quality. The Alps pot is carbon film type and quite warm sounding. To keep that sound use carbon film series resistors for the shunt pot mod. For a slightly cleaner sound use metal film resistors with the Alps.

[Paul Stoneman]

Excellent, many thanks Richard, I will get some bits and play.
Kind regards Paul.

[Paul Stoneman]

Good morning Bob,
My sincere apologies I did not see your post above Richards, thank you for the information, I will get some parts.
Kind regards Paul.

[FreddieT]

Welcome Paul.

I agree with Richard about the improvement gained (pun accepted) by using a Pre3, in my case ahead of the WD KT88. I'm also using the shunt arrangement for the pot, and when I feel like opening the pre up I'm going to try carbon film and Sinkoh 68ks for the series element. Actually it isn't quite a Pre3, but the audio circuits are.

More later...

Enjoy the forum.

F.