45 fans – expanded horizons upstream?

[rick57]

Has anyone done a 45 preamp?
. . or have any suggestions?

I am looking for a preamp circuit . . I have spare 45s (and using 45s might aid integration in a biamped system, with 45s on the tweets).

So what 45(?) preamp circuit do you suggest, preferably with priority to: dynamics, then detail, & 3rd (if not too conflicting) lack of harshness.

(The 45 doesn’t have any qualities that don’t suit it being in a preamp, eg microphonics?)

Any advice appreciated

Thanks

[ErikdeBest]

Hi Rick57

Here is a design using a 2A3 for line stage duties. A 45 seems to be half of a 2A3, so maybe it serves as inspiration
http://triodeguy.com/line_stage1.htm

Erik

[Miles Prower]

Originally posted by rick57
Has anyone done a 45 preamp?
. . or have any suggestions?

I am looking for a preamp circuit . . I have spare 45s (and using 45s might aid integration in a biamped system, with 45s on the tweets).

So what 45(?) preamp circuit do you suggest, preferably with priority to: dynamics, then detail, & 3rd (if not too conflicting) lack of harshness.

(The 45 doesn’t have any qualities that don’t suit it being in a preamp, eg microphonics?)

Any advice appreciated

Thanks

"The 45 doesn\u2019t have any qualities that don\u2019t suit it being in a preamp, eg microphonics?"

Just a u= 3.5. This is not preamp material since there is precious little voltage gain. You might get an Av= 3.0 if you use an active load. You'll get less if using passive, resistance loading.

[rick57]

Hi Erik

Yes I believe the (later) 2A3 is a double (earlier) 45.

That 'line stage' does other things as well eg XO. If I can’t find a specific 45 circuit, I might contact the designer triodeguy to see if he can split/ adapt it?

Cheers

[rick57]

> Just a u= 3.5

For a high efficiency system, I (like SY's "Heretical Unity gain line stage") am after little or no gain.

Maybe SY's could work (with changes of ??) with a 45?


Cheers

[jeff mai]

Instead of asking others to redesign circuits, why don't you take a stab at doing it yourself?

[rick57]

Jeff

I got as far as looking at the tube parameters, the 45 is very different from the ECC88 (6DJ8). I’m a way off understanding SY's circuit, though it’s simplicity is appealing. Even to understand his thread, some time on the basics is Needed.

Rather than reinvent the wheel, I will first see if some one has done a 45 pre. If none has (successfully to ‘publish’), maybe there is something wrong with the idea.

Thanks

[jeff mai]

Originally posted by rick57
Rather than reinvent the wheel,

Your previous post was an invitation for someone else to reinvent the wheel, so clearly you aren't totally opposed to the idea.

[rick57]

That was a bit rich, I was feelin groggy at the time


I hear the RCA manual has a 45 circuit.
Though also maybe a 10 preamp sounds more punchy - maybe that is just more gain??

[pinkmouse]

Have you read Morgan Jones' book yet? It helped me a lot during my construction of SY's line stage.