#26 pre amp

[merlin el mago]

At least one thing to don't worry about

 

[merlin el mago]

Hi Felipe,

as I wrote you can connect the secondary either way depending if you want the stage to be inverting or non inverting. Some transformers have different high frequency performance depending on the polarity. Not the Lundahls. So you can choose.

Best regards

Thomas

Thanks again for your kind support Thomas

 

[merlin el mago]

No, use a resistor the value of the input impedance of your power amp as dummy load.

I ask Erno Borbely.

My power amps have an input impedance in unbalanced mode of 100K, how to calculate de RC filter?

 

[mthoi]

I finally had the 26 boxed and tested. Hum free and driving my 845 tube amp. After 20+ hours, I think it would be the mainstay to replace my 76 tube preamp.

 

[vgeorge]

My power amps have an input impedance in unbalanced mode of 100K, how to calculate de RC filter?

I would start with a 2.2nF to 3.3nF cap and a 20K trimmer and watch squares and the resonance on the scope.

 

[merlin el mago]

Like the pic?

 

[Vinylsavor]

Hi!

10KHz no load

Don't get too worried about square wave response. If you want good square wave response, a transformer coupled line stage will not get that.

Listen to the thing.

Then you can still experiment with loading and RC filters, but I doubt you'll really need it

Best regards

Thomas

 

[iko]

I finally had the 26 boxed and tested. Hum free and driving my 845 tube amp. After 20+ hours, I think it would be the mainstay to replace my 76 tube preamp.

Looks great! Thanks for sharing!

 

[vgeorge]

Like the pic?

No, RC in series parallel to the load.
Agree with Thomas, like I said before. Listen first without and then decide.

 

[merlin el mago]

OK guys a will listen before to decide.

 

[merlin el mago]

I finally had the 26 boxed and tested. Hum free and driving my 845 tube amp. After 20+ hours, I think it would be the mainstay to replace my 76 tube preamp.

Great work

 

[amandarae]

I finally had the 26 boxed and tested. Hum free and driving my 845 tube amp. After 20+ hours, I think it would be the mainstay to replace my 76 tube preamp.

Very nice!

 

[stajo]

Did Iko do any scoping on the gyrator loaded toobz?

 

[iko]

I did, yesterday. No wiggles on the horizontal lines, no overshooting. I'll take some pics and post them when I get a chance.

 

[rclourenco]

I finally had the 26 boxed and tested. Hum free and driving my 845 tube amp. After 20+ hours, I think it would be the mainstay to replace my 76 tube preamp.

I like it!, also like the Garrard! Are those Titleist Pro V1

Enjoy it.

 

[andyjevans]

There speaks a true golfer!

 

[stajo]

What are the sonical differences to for example Top Flite Strata?

 

[stajo]

My power amps have an input impedance in unbalanced mode of 100K, how to calculate de RC filter?

I'm not sure how you got in on RC filter. Maybe that is the thing, I dont know. It will cut off outgoing HF. If you want to ease up the ringings in the OPT tho, I think one can either experiment with zobels etc on the primary or, for the bold, introuduce some small GNF with a cap over the resistor.

 

[rclourenco]

What are the sonical differences to for example Top Flite Strata?

I would say harsher sound, this ball is very hard. The other I mentioned gives you completly different control and fill throughout the all MPOC (Musical Process On Course).

 

[Joao@AltheaMusica]

Don't get too worried about square wave response. If you want good square wave response, a transformer coupled line stage will not get that.

A new miracle in electronics... I take my hat off!