Speaker suggestions needed

[tyerkey]

Hi All,

I have recently completed my first attempt at a DIY stereo.  I have a Quickie preamp, 2 Nelson Pass designed Amp Camp 5 watt class A monoblocks, and bookshelf homebuild speakers with Fostex FE126En drivers.  The problem I have is very little volume.  I guess I went the wrong way with the speakers.  I chose them because I heard a set of speakers with the same drivers being powered by a S.E.X amp that was putting out less than 2 watts per chanel.  I thought I would be fine with my massive 5 watt system. 

As it is, I can get listenable volume if I turn the Quickie up past 3/4 volume, and then I get a lot of distortion.  I have PJCCS upgrade, but I have not installed it yet.  I hope for a bit of reduction in the distortion when the upgrade is installed. 

Does anyone have any suggestions for drivers that would work well with this massive system? 

Yes, I know I could just build a bigger amp or upgrade the whole system.  That is what I plan to do in the long run, but I am new to this electronics thing, and right now I am happy to not have let the majic smoke out of anything that I built so far.  I'd like to have this system work so that  my wife will be passive when I build the next system...

Any Suggestions?

 

[Doc B]

Hmm. That amp circuit has a gain of 14dB, and with the additional gain of the Quickie in front of it should be getting loud more easily than a SEX amp. The Fostexes are reasonably sensitive for their size according to the published spec of 93dB. Based upon those numbers alone it should work well. However the input impedance of the amp is pretty low at 10K and that could be the issue. PJCCS will raise the output impedance of the Quickie from 2K to 4K and thus may not be the best way to go in this particular situation.

This is assuming that everything is working the way it is supposed to be.

 

[tyerkey]

The volume of stuff that I do not know is huge and growing.  Could you please explain why the increase in the output inmedance of the quickie will cause a problem?  Assume you are talking to somebody with the technical training of a Ph.D. in psychology.

 

[fullheadofnothing]

The reason for the impedance issues is the rule of thumb that you get the best power transfer when you're working into a load about 10 times bigger than the output impedance. I learned the physics of this once and don't remember the reasons anymore, but it's definitely observable.

Additionally for your circumstances, what source(s) are you using? How big is your room? Is your speaker design the same as the one you heard previously? If you heard the driver in horns before, that's going to be more efficient than a small box.

 

[earwaxxer]

What I would do, if you can, is take the Quickie out of the circuit and see if you can use a digital volume control, or preamp from a receiver, on your front end. Not sure what your front  end is. I usually do that to try to figure out what may be going wrong, if anything, with the Quickie. Even a variable output from your TV etc.

 

[tyerkey]

Thanks for the  info and reply.  

The speakers are almost identical to the ones I heard.  I may build a horn set up in the near future.  I was using an iPod, but I switched to an old Nakamichi CD4.  The output level increased when I went to the cd player, and the distortion did too.  My room is really too big for the system, but I am not asking it to blast.  I would settle for a good background music level right now.  I may move it to a small room tonight and see if my overall impression changes.  With that said, the SEX amp with the same drivers was in a very similar room and was far louder.  

I may have to do a serious recheck of the components to be certain they are working correctly.  

 

[tyerkey]

Okay,

So I get home tonight and I bring all of my electronics gear into the house to do a thorough check of all of my components.  I sit down, and I think what have I not checked yet?  I know the quickie worked well with the old Rotel amp before it died.  I know the speakers work.  I know the amps checked out the last 3 times I checked.  I know the batteries in the quickie are brand new, but I never actually checked them. No.  :-\ It couldn't be that.  I took them out of the packages and put them in the Quickie myself.  Crap.  So I check the D-cells.  They are right where they should be.  Now for the 9 volts, 9.7, 9.7, o.54, 4.5.  No!  I find 2 more good 9 volts and replace the dead ones.  I turn on the preamp, click on both mono blocks, slap Harvest moon into the CD player and hit the play button. 

I have been listening to the system for the past 2 hours.  Rather than having to crank the preamp all the way up, It has been running at about 25% volume.  It is almost too loud for the room at that setting.  Everything in the system is brand new, so I have a lot of listening to figure out what I like about it.  It started off way too bright, but it mellowed and actually developed some base during the play time.  I went through a few CDs that I love, and I have to say it all sounds great.  It's the first time I really have gotten to listen to the quickie after building it last winter.  Awesome! 

Thanks for the suggestions.  Always check to see if the batteries are good and everything is plugged in.   

Now where did I put the power cord for the quickie? 

 

[earwaxxer]

Now where did I put the power cord for the quickie? 

lol! - Thats interesting that the volume decreased by that much with low voltage. It must also be some funky current stuff going on with the dead cell. When my grid battery goes south it just stops working at some point. No real warning. Thats usually around 15 volts. - agreed with your impressions though!