Purpose of CF mod on Pre2?

[hawkinsec]

The power amp is a Quad 405 clone built by Paul Baldwin in West Sussex (see https://reelaudio.co.uk). It is probably also worth mentioning that I get the same degradation in sound quality when listening through my HD83 if that is connected to the op of the pre rather than the tape out. I'm not sure whether this might be usefil information or a red herring, but when I received the three items, both of the sleeve connections had fallen off the op phono sockets on the Phono2 and there was faulty soldered connection on the power supply, which resulted in there being no heater supply voltage. I suppose that it is not beyond the realms of possibility that the preamp has suffered in some way too. It wouldn't be too much trouble to re-solder all of the board connections in case one or more have gone hr or something..

[Chris]

I would like in the future to have a "shoot out" with a few of the different pre amps we use, if any one is interested. Once this virus has been buried.

I stripped out nearly all the connections in my pre2, so once I found some Interconnects that I liked they were soldered directly to the pots, securely fixed on entering the case, no toggle switch or selector switch, the only sockets I have are pre-out using WBT sockets.

When I get time I really want to build new enclosures for the WAD kit, so there is more space to play around with.

Chris.

[Chris]

Eddie, it's a worth while exercise to run over all the solder joints with some fresh solder, don't pile on the solder, just wipe clean the solder iron between each joint, wetting the tip with small amount of solder.
isopropyl alcohol can be used to wipe away any flux once finished.

Chris

[hawkinsec]

Originally Posted by Chris

Eddie, it's a worth while exercise to run over all the solder joints with some fresh solder, don't pile on the solder, just wipe clean the solder iron between each joint, wetting the tip with small amount of solder.
isopropyl alcohol can be used to wipe away any flux once finished.

Chris

I was thinking of just going the whole hog and removing the old solder. Is there some merit in not doing this?

[Greg.]

Originally Posted by hawkinsec

I was thinking of just going the whole hog and removing the old solder. Is there some merit in not doing this?

I doubt that is necessary. Just follow what Chris suggests and see if it fixes your issues.

[Chris]

"Removing the solder" If the component leads have been cut short, you may find it a pain to try to sit them well, more chance of lifting the pcb track and component damage.

There is a big difference between diy soldering and someone who does it every day as a job.

Chris.

[hawkinsec]

Originally Posted by Chris

There is a big difference between diy soldering and someone who does it every day as a job.

Chris.

I know

[bob orbell]

Gentlemen, I am being honest with my findings of the Pre II and I apologise if I have offended anyone, I can only speak as I have found an item, I had a Pre II, I also borrowed a Pre III from Peter C, the difference was immense, the III had bass and power the II was thin weedy and, well I shall not say more, except looking back through the forum there was a lot of dissatisfied owners, I rest my case. Bob

[John Caswell]

Hi
I am very puzzled by the comment "but all detail,bass and treble are absent."
Every pre 2/3/4 have measured very similar and to my ears at least sounded similar, so it would seem that there is something wrong with your unit, but what I do not know. Are you using it "as is"or do you have some attenuation somewhere for gain reduction? Is the Zobel network fitted? Any further information would be helpful.
The only problem that we had with the pre 2 was electromagnetic pickup due to the magnetic fields from other devices in the vicinity ie amplifier power transformers. It is a transformer problem not a unit problem. Some attempts were made to reduce this with a copper tape but really the only solutions are distance and position with regards to the other magnetic fields. Eg when building an amplifier the cores of the power tx, op tx, and choke should ideally all be at right angles to each other, not always possible of course.
My own MM/MC phono stage throws up some slight hum on MC at almost max volume but rotating it 90º clears that completely.

John

[bob orbell]

John, are you referring to my post ? if you are, it went in the bin many years ago and I moved onto an Aikido cathode follower. Bob