If anyone is still looking for a SLP-98


I see that Cary Direct is selling a preowned unit for $2395.

immatthewj

@harpo75 

Yup, I've read about the Sweet Little Preamp and the 98 significance. Same with the 80. 90. 94 and the 05 I think. Apparently, Dennis Had used this "code" in a number of builds, at least preamps. Maybe he had some meaning behind all the numbers. Who knows?...........Well, you might I guess. The F1 seems to be a very nice upgrade from what I've read. Hexfred and direct coupling being more. Not sure what else is in there, several blue smaller caps, wixa or something like that? Definitely has the Jensen gold/yellow caps. Not sure what to look for as to grahill switch. Having the Lundahl step up for MC I guess is another fair upgrade. I have a photo of the guts but haven't figured how to post yet. It appears that we have to pick a host site for photos and then bring them here? Haven't done that in a good while but will try it if that's what we have to do. 

@harpo75 , I am going to hijack my own thread a little bit, but I guess since it is mine (the thread, that is) it is okay.

Anyway, a couple of generalized questions about the SLP-05, when the power supply is turned to 'ON', as I understand it (from the owners manual) all that is doing is putting it in a mode where turning the preamp knob to 'ON' will activate the power supply, but nothing else?  In other words, with just the power supply knob turned to 'ON', the only thing that is happening is that the blue LED light on the knob comes on, but if I am reading the manual correctly, nothing else?

And I am pretty sure, but I will ask anyway, that the meters on the power supply are indicating plate voltage and plate current of ONLY the rectifier tube?

Sorry, pretty simpleton questions, but I am a simpleton, and I just wanted to make sure that I was understanding this correctly.

 

 

You are right on both questions.
Yes, when the power switch is ON on the PS it is only applying power to the relay board inside the PS. This powers a small 12V transformer that powers a relay. The relay is then activated by the switch on the main Preamp when it is set to ON.
The switch on the preamp connects a ground wire back to the relay in the PS which turning on the power to the main transformer. That transformer provides the high voltage and the filament supply.
The reason for all this is to keep all AC voltages out of the actual Preamp chassis. The Preamp switch triggers the relay by connecting it to ground.
Am I explaining that well?

P.S.  The meters are connected to the DC voltage coming from the rectifier tube like you say.  They are not perfectly accurate but are a great reference point to keep an eye on.  Once warmed up they should always read pretty much the same.  Baring some AC voltage variations from the house wiring.  Sometimes people freak because the current is reading a little low.  You may also notice  then that the voltage is a little higher that day. 
Where the meters are useful is if you suddenly notice a higher current draw.  This would mean there is a short somewhere.  Start by changing the rectifier tube.  If a new tube doesn’t correct the high current draw then you either have a 6SN7 tube shorting or a bad PS capacitor.  If you pull out all the 6SN7 tubes and turn it on and it still drawing high current with a good rectifier tube then you know you have a shorted capacitor somewhere.  

In my setup I’ve found I like the old NOS Sylvania 6SN7 chrome top tubes except for the balanced input position tubes.  Because my DAC tends to be a bit lean for my taste I really like the Sylvania 6F8G tubes (which need to be used in an adapter).  These tubes sweeten things up nicely yet don’t loose much in the way of dynamics.