2. amps-preamps
  3. 125908-371

Active and passive preamp in one chain ?

As I just discovered, my Redgum integrated amp has a passive preamp in it. No wonder, I don't have enough gain and consequencially not enough weight in sound when playing records. A lot of transparency though. To compensate I currently run phono/cassette deck/ Redgum at the silght expense of resolution.
How would it be if I added, say, some tube active preamp? No, not ready to go fully separates at the moment. Running MM cartridge and phono gain setting is fixed at 46db, I think. In other words, replacing deck as a sort of an active preamp with a true active preamp.
inna
xrayz
78 posts
 
The only input impedance I can find for your amp is 10K ohms. That's pretty low and it will cut down on your choices for a preamp. Also, if the amp section is designed for a passive pre, the voltage output of an active pre could very well overload the amp. I would write to Redgum and see what they have to say.
erik_squires
5,268 posts
 
Inna,

That's not necessarily a terrible thing. You have gain, but it's in the amplifier. Having a single gain stage is usually a very good thing, less distortion, less noise, less parts to optimize. This is by no means a weird situation.

Having said that, depending on the input impedance, yada yada, it may be optimum to have a buffer BEFORE the volume control, ensuring the apparent input impedance is volume independent.


Now, whether it sounds good to you or not.... That's another story entirely.

inna OP
5,245 posts
 
I see. So what kind of active preamp do you think would work? I am not technical, don't really understand this stuff. To write to Redgum is a good idea unless they get upset by the fact that I think that there is not enough overall gain in the integrated.
Not that I have a big problem with the curent phono/deck/Redgum set-up, except that I do lose some resolution. Otherwise the amp is quite good. And I do make recordings from records onto tape from time to time. I just thought that something inexpensive but reasonably good, something like Rogue, might temporarily make things better until I am ready to overhaul the entire signal chain.
xrayz
78 posts
 
@inna  I took a quick look at The Rogue preamps' output impedance and they all seem low enough that impedance mismatches shouldn't be a problem. It looks like your idea should work, it just seems so unusual. I'm not a tech guy either, and I'm not sure how trying this would actually sound. Is there any other phono preamp that could give you more gain? I'm sure there are others on here who could give you much better ideas than I.

I used to have a Redgum integrated too, and the people there were extremely nice and helpful whenever I wrote them. They may have some sort of simple answer to your problem. Good luck.
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