S.E.X. Amp Built and...

[Ivan303]

  In short, the 'Spud' is certainly no 'Dud'.  And not a toy amp by any means, even if 'flea' powered and costing mere $mid-hundreds$ not $thousands$.

Haven't tried it as a headphone amp as yet but instead I am using it to drive my 105dB EdgarHorn Titans.

And I must say it's doing yeoman's work. 

I added the C4S board and (perhaps) heard more clarity and also maybe less 'grain', if there even was any 'grain' to start with.

Dead silent with or without the C4S board.  If I crank up the volume on the amp and turn down the volume on the tube pre-amp I'm using, I can hear some tube rush coming from the pre-amp but the 'Spud' is dead silent.

What's next?  Maybe a better (or at least more expensive) DC blocking parafeed cap, that little black Solen is not very pretty, but that's about it.

Plan to build another one to bi-amp the horns with the future possibility to implement an active x-over. That's something I could not afford to do with a Directly Heated SET amp kit like the MonAmour. 

At a bit more than $500 a pop, bi-amping is financially feasible.

Be interested in hearing anyone's thoughts on other 'upgrades' they have performed.



 

[Paul Birkeland]

Just be careful that you don't end up spending Stereomour level money on upgrades for the SEX amp, as the Stereomour is overall a better product out of the box!

A PEC volume pot is a nice upgrade, but it sounds like you're using the SEX amp as a power amp, so that's not exactly necessary. 

[Ivan303]

Clearly the volume pot is still in play driving the EdgarHorns at a bit more that 50% of max.  At full max the tube pre-amp driving it is turned nearly all the way down and its background noise/tube rush can be heard as we amplify its noise level with the S.E.X amp.  Must have quite a bit of gain?  Certainly more than the 300B monoblocks it replaced.

Might solder in  fixed resistors at some point but certainly not 100% max volume (no series 'R' and 100K to ground?) which I assume is the same as the pot at max?

But that little black Solen is SO ugly.    It must go, but worry not.  Nothing approaching the cost of a MonoMor.

[Paul Birkeland]

The SEX amp has pretty low gain (I think around 15dB).   If the pot is all the way up, it will just act as a pair of 100K resistors from signal in to ground.

The Stereomour is half the price of the MonAmour, hopefully your parts changes don't push the cost of your SEX amp close to either...

[Natural Sound]

But that little black Solen is SO ugly.

Unless you run your amp upside down who cares? I've built a couple of S.E.X. amps and spent big bucks on parafeed caps in the past. The Solen is actually a very nice sounding capacitor and is staying in my latest build. Often times I find that capacitors change the sound of the amplifier. More often not for the better.

[Ivan303]

Unless you run your amp upside down who cares? I've built a couple of S.E.X. amps and spent big bucks on parafeed caps in the past. The Solen is actually a very nice sounding capacitor and is staying in my latest build. Often times I find that capacitors change the sound of the amplifier. More often not for the better.

Amp sounds great as it is, without a doubt and I doubt I'll spend more than a few $$$ on upgrades.

[Ivan303]

The SEX amp has pretty low gain (I think around 15dB).   If the pot is all the way up, it will just act as a pair of 100K resistors from signal in to ground.

I doubt my 300B monoblocks have even that much as it has 100K input impedance and requires a pre-amp even with horns.

100K input impedance with the pot at max?  But no 'R' in series?

If I didn't have a number of inputs I try it as an integrated and forget the pre.

[2wo]

I am using the Solen Silver as parafeed cap in my 45 amp and am pretty happy with them.

Not very expensive and a bit  prettier  ...John

[Ivan303]

I am using the Solen Silver as parafeed cap in my 45 amp and am pretty happy with them.

Not very expensive and a bit  prettier  ...John

Yes, if one can't hear the difference on can at least say "but they're SILVER."  :-)

 

[Ivan303]

New parafeed caps are in house.  Not THAT expensive, about the price of the C4S mod.

Let them cook overnight and...

Pretty good!!!

Streamed Royal Liverpool Phil./Petrenko's new 'Petrushka, a really good recording with lots of individual instruments highlighted across the sound stage and...

Originally looking for a tube headphone amp capable of doing double duty with the horns as I upgraded the 300B monoblocks that are getting long in the tooth.

Now I just might build a second S.E.X amp and bi-amp the horns and maybe go to active x-overs.