PSU3 and Phono3 build

[pre65]

Each to their own.

I built a cathode follower pre based on the Pre2 CF circuit, but I preferred my Pre3.

[bob orbell]

Don't get me wrong Philip, the pre 3 is very good but just a tad to bright in my system, mind you it could well be my speaker's with those ribbon tweeters, very revealing. BOB

[Greg.]

Originally Posted by pre65

Each to their own.

I built a cathode follower pre based on the Pre2 CF circuit, but I preferred my Pre3.

The cathode follower circuit suggested in the WAD FAQ section came originally from Morgan Jones, adapted for the article by Neal Gibbons. The intention was to convert WAD Pre II to a Cathode Follower circuit using the PSU II power supply. No other alterations beyond what Neal published in the article were anticipated.

Philip, in my view, you've been significantly disingenuous in your sweeping statement because you have not made reference to all the alterations/additions you experimented with and built into this circuit in your own system. What you ended up with was very different from that original Cathode Follower circuit tweak. You did not build a WAD/WD Cathode Follower Pre II/III alternative in accordance with the published article but actually deviated from it. Having deviated away from the original, how can your opinion be of any value? Many of us who have adhered to the conversion to CF from the original, feeding a WAD/WD power amp have been totally satisfied. Your experience is out on a limb, but then you don't use WAD/WD power amps, do you! Maybe that is the relevant synergistic issue

Here are the threads where Philip explored the CF option on his WD Pre III. Remember, he's not powering into a WD/WAD power amp.

http://www.audio-talk.co.uk/phpBB2/v...thode+follower

http://www.audio-talk.co.uk/phpBB2/v...ower&start=105

[pre65]

Well Greg.

I had to read those threads you linked to, to remind myself what I actually did.The pre amp in the first link (with a 12A) was never actually built.

My first attempt at a pre to better Pre 3 used two 6SN7, after that failed to please I tried again with a cathode follower version.

This was a quote from one of my posts.

"Before it finally bites the dust, I'm going to try it as a cathode follower without gain using the 6922 valve I have. Just to please Greg."

Here is the said CF experiment in the flesh.



Now, strangely enough, your second link missed that bit.

So, I did try a cathode follower following as near as possible (using bits from my spares box) the Pre2 details from FAQ.

It was not bad, but as I said before, I still prefer Pre3. That is my opinion, and my opinion alone. Make what you will of that. No one has ever suggested WD pre amps should only be used with WD or WAD amps, have they ?

I use Pre3 with a variety of amps, mostly valve single ended, but valve push pull and mosfet single ended as well, and it has been the "reference" Pre amp for DTB and others at many an Owston and Eggborough.

If you and a million others like Pre2 as a cathode follower, then that's fine by me, but my opinion is as valid as anyone's.

[Richard]

Originally Posted by pre65

That is my opinion, and my opinion alone.

Oh no it's not

The CF conversion to Pre2 was first suggested back in 2003/4 as an alternative to Pre2 for reason of hum and excess gain rather than sound quality. Greg's Pre2 was suffering in particular. I posted the original suggestion to use the earlier 1993 WAD Pre CF circ below. It was received with luke warm interest but Neal did a similar one and wrote it up. It was a success re hum and gain but I'm not sure the sound was better.

Greg's works well with his power amp and the 2 probably complement each other. We heard them both at my house. His power amp is very explicit and exciting whereas the pre is somewhat laid back. We did compare the pre alone with a passive pre and a TX pre. It was all very interesting and great fun I'm not sure if Neal still uses his or has moved on. Really, dozens of circuits could be built inside Pre2 case and powered from PSU2.

Back then for example I had tried Bruce Rozenblit's "grounded grid", which had a CF output. Today, pre circs such as Aikido might be worth a go but please don't lose sight of how new, different, and good Pre3 is, or think you might know how it sounds without having a listen if you've already had Pre2!

Pre3 is not a CF and is completely different to Pre2. Really, anyone who had/has Pre2, or any other pre for that matter, might want to have a listen to Pre3 in comparison. Things move on; Pre3 has no hum whatsoever and sounds amazing. Topology-wise it is all single ended with no feedback, not even local. PSU3, PRE3 (circ at bottom) and Phono3 are amazing value imho and well worth moving on to from earlier designs.

[BOONDI]

Cheers Richard, by spooky coincidence I was about to find out about blue LED's for my hot rodding of HD3...

Saved me a ton of time and typing....

[Richard]

Originally Posted by BOONDI

Cheers Richard, by spooky coincidence I was about to find out about blue LED's for my hot rodding of HD3...

Saved me a ton of time and typing....

You're welcome Derek Bear in mind the led illustrated is a mod and is powered from the 6.3V DC heater line.

I'm not sure if Matthew has changed the leds on PSU3/Pre3/Phono3 but they were yellow, of different types, and powered via different supply/resistors. That gave 3 different-looking yellow leds...

The one shown can be fitted the same to all 3 units making for a more uniform look and the light level is nice without searing your eyeballs

[Greg.]

Hi Richard,

Much thanks for the clarification on Pre2 coverted to cathode follower. My latest understanding is Neal, like me is still using that version.

I believe that the type of power amps Philip builds and uses will generally require gain and in such circumstances, his like of his Pre3 over the Pre2 cathode follower convertion is completely understandable.

Having said that, I have a mate who built Pre3 to match his WD88VA and he converted to the CF circuit immediately after hearing my CF pre-amp in his system. He remains totally satisfied that it constitutes an improvement over the performance of Pre3 and he has subsequently built this CF pre-amp for another friend who uses solid state power amps to his total satisfaction. That person has commented that this CF Pre is the best Pre he's ever heard.

Ultimately, I think this is a suck and see 'synergy' thing. I and some others prefer the CF option into our WAD/WD amps. It seems to work for us. For others it may not work but I suspect the power amps others use will need to be part of a critical consideration within that amplifier blend.

One long standing question remains. Considering the sensitivity of just about all the WAD and WD amps, why does their Pre amps, beit 2 or 3 need to have so much gain?

Regards,

Greg

[pre65]

Originally Posted by Greg.

One long standing question remains. Considering the sensitivity of just about all the WAD and WD amps, why does their Pre amps, beit 2 or 3 need to have so much gain?

Regards,

Greg

Why not, why are WAD / WD amps so sensitive that a pre amp almost becomes unnecessary.

[Richard]

Hi Greg,

Yes I'm sure you will be right about your system, we heard the pre/power and it works very well indeed. I know Pre3 sounds better in mine though with my shyer sounding 300bpp and now with the Glasshouse 300bse. In fact I've made no tweaks to adjust sound balance, not even valve or cap changes, since putting in the Glasshouse and that amp has revealed more than I knew was there.

There's no reason Pre3 has to be used with any particular power amp though WD ones are an obvious choice. There is 6x = 15dB gains as standard and very low output impedance which makes it a more universal preamp than one with no gain; it's easy to lose gain (with a divider or shunt pot vol control or simply turning down the vol control) but hard to get it.

The 300bpp without feedback is particularly sensitive but many power amps would not get sufficient drive from a CF pre particularly if the shunt pot volume control was used.