adding a quickie to a s.e.x.

[guf]

is there any logical reason for it? i built a quickie for my main system but tried it out on my desktop between the sex and the orca's. i'm not sure if it sounded better but it sounded different. my quickie is just in stock for as of now.
thoughts?

 

[Doc B]

I think the only technical justification would be to boost the signal from a low output source. But it certainly won't cause any harm and might change the tone or other sonic aspects in a way that you find an improvement.

 

[corndog71]

I've run my sex amp with and without a quickie.  I like the sound both ways.

 

[denti alligator]

I like mine with. Can't put my finger on it, but it's more alive sounding. After much experimenting, however, I've come to use the two as follows: the Quickie at 80% volume fixed; the SEX as volume control. I've found much more microphonics using the SEX as a power amp. Anyway, it sounds quite nice this way. I like th extra boost in gain, and it colors everything nicely.

But maybe I'm just imagining that...

 

[adamct]

Doc,

I'm curious...I know that you guys recommend using a powered pre-amp with power amps, because it helps to address impedance mismatches between the source and the amp. Why is this less of an issue with headphone amps?

Best regards,
Adam

 

[Paul Birkeland]

Why is this less of an issue with headphone amps?

A headphone amp will generally have adequately high input impedance, and very low output impedance.

If you had, say, a Reduction, then 50 feet of cable feeding your headphone amp, then you'd probably want a preamp next to the Reduction to drive the cable.

With most headphone amps, the source gear is pretty close to the amp, so this is not an issue.

 

[adamct]

Thanks, Paul.

Just to confirm that I'm thinking about this right: although source and amp are usually close together in a speaker system, too, I take it that speaker amps tend to have lower input inpedance than headphone amps, is that right?

 

[Paul Birkeland]

They can indeed, even some of the more popular DIY designs can be as low as 10K.

There can also be an increased cable length when you have a few sources cabled to an input selector/attenuator, then more cable feeding to the amplifier.

 

[adamct]

Got it. Thanks!

 

[boulos]

I just finished building the Quickie 1.1 and I'm pairing it with the SEX. It sounds much more musical with it. I set the SEX at highest volume (I get no hum) and use the Quickie for volume control.  The Quickie has PJCCS upgrade and Solen SB270 caps.  I'm not having any issues with microphonics.

 

[Paul Birkeland]

Ooo, you got a pearl plate, sweet! 

 

[JamieMcC]

That pearl plate looks nice,  I have a large diy store about 2miles away and was looking around the other day they have a massive selection of marble and granite tiles the white marble looked similar. Sold in packs or individually for samples for just a couple of pound. I just thought straight away what a great idea for interesting top plate to place over the alloy one. 

 

[boulos]

Ooo, you got a pearl plate, sweet!

yeah It was a very nice surprise when I opened the box.  I'm amazed at how quiet the Quickie is. I expected some noise when I raise the volume of the SEX to the max.  When I tried out the BeePre I built for a friend, I could only raise the volume 2/3 the way up. That said, the BeePre+SEX combo was jaw-dropping. 

Thanks so much for the recommendation on the Solen caps.

 

[mcandmar]

I see your a fan of Sylvania tubes too

 

[boulos]

I see your a fan of Sylvania tubes too

Totally  

I found I really like them on the SEX. Also, on the Quickie, these two Sylvania tubes gave almost identical voltages on both sides (within 0.1V) and don't seem to suffer from microphonics.  However, I did two things that I felt would help: I stuck six thin (~1mm) rubber strips on the groove in the base where the plate sits (four corners and two in the middle of the long edge); and I left a very thin clearance between the tubes and their sockets (they're almost all the way in, but barely resting on the sockets).

The rubber strips I used are the spacers between bumpers (see example image).

 

[mcandmar]

For the SEX amp those are the tubes you want, Sylvania black plates with the cut away top supports.  They are hard to find though i have seen them rebaged as a few other brands.  The grey plates are identical to GE or RCA, cant remember which.

On the Quickie tubes, were they the early ones in the green box's, or the later yellow/black box, or JAN stock?

 

[boulos]

The Quickie tubes are SC JAN tubes labeled RMA-3S4 (radio manufacturer's association, which changed it's name in the 50's) from Galvin Inc (the current Motorola, which apparently made the first car radio).  So these are probably from the 40's.

 

[boulos]

BTW, I just checked and I have coin-base tubes with the same construction from Ratheon. I remember finding them noisy (almost like too much gain).  I should give them another shot.

 

[mcandmar]

That's good to know, i'll keep an eye out for them.

Thanks,

Mark