Newbie Introduction

[drewh1]

Hey - I just want to introduce myself. I just bought a Stereomour kit and am awaiting delivery. Already have my Stahl workstation, solder and am reading the manual. Can't wait to build it and try it out. I used to build computers (a long time ago) and have DIY'd cables and a subwoofer. High voltage analog circuits are definitely new to me.

I have been an SS guy for many years, currently have an Ayre QB9 DAC with Ayre AX7e, GreenMountain EOS HDs (90dB, 4.6 ohm), DIY Sub with Seas 10" driver,  all fed by J-River on a custom built music server in a Silverstone cabinet.

I have enjoyed my system for about 3 years now without changing much (except for speaker cables) and now I want to try tubes. My friend lent me a MiniWatt 3.5 just to see what my speakers might do with 3.5 watts. Even though they are not super efficient,  the Miniwatt actually sound quite good for guitar, voice, violin. Not so great for piano, rock, orchestral, you know. I loved Iron and Wine and Alexi Murdoch for instance. I thought about buying an Elekit 300b but after researching everywhere, decided the Bottlehead kit was the way to go and I could enjoy low watts and still rock out with my ss when I wanted to.

So I am impatiently waiting and resisting the urge to start buying upgrades before I even have the kit in my hands. Really want a Goldpoint! I am looking forward to participating in the forum and will have some questions for sure once I start on it. Also have wanted to build a set of single driver speakers for a long time but that's a different forum

Drew

[Grainger49]

Drew,

Welcome!  You will find all sorts of assistance on this board. 

It sounds to me that you are at home with a soldering iron.  Good!  You might find that 3.5 tube watts more dynamic than the MiniWatt.  Some years ago I tried my old speakers on the then current 3.5WPC Bottlehead and heard much of what you did.  It was good on small groups, ran out of steam on true rock.  Those speakers were not tube friendly.

As for single driver speakers, check out this link:
http://www.bottlehead.com/smf/index.php/topic,1943.0.html

[drewh1]

Hi Grainger - I appreciate the welcome, you are quite a presence on this forum. I am sure I will be needing your help along the way.

Thanks for the link - I am going to live with these speakers for a while - I went through a lot of trials to get to them. When I do go to SD's I will definitely DIY, Transmission Line likely. I have been drooling over the Seas Exotic for some time now, of course the 96db version is even more expensive.

I am also sure the Stereomour is going to be a very different 3.5 watts! My issue with the MiniWatt was not SPL but with transients and timing. Instruments requiring a sharp attack just got muddied and well, frankly, pianos and cymbals sounded terrible. I assume this has more to do with the qualities of the tubes and power supply. The Ayre DAC is particularly good with these things and I have really appreciated the quality of the reproduction I get with Hi-Res files.

I do have a question though - is there a crossover solution that would not require the addition of a pre-amp between my DAC and the Stereomour? If so, I would hi-pass to the Stereomour and run the sub separately

Thanks again. As much as building the amp will be fun, sounds like this forum is a great place to hang out too.

drew.

[Grainger49]

Drew,

Last thing first:  The input impedance of the Stereomour is 100k ohms.  You can calculate a straight 6dB/Octave crossover using the first order formula

F_o=1/2*Pi*R*C

F_o=crossover frequency
2 is a constant
Pi=3.14159... another constant
R=the input resistance
C=the capacitance in series before the input pot of the Stereomour

Solving for the capacitance, since you will know where you want to crossover:

C=1/2*Pi*R*F_o

Be certain to divide by 2*Pi*R*F_o

To be certain I understand, do you want a simple crossover to eliminate the low frequencies from the Stereomour?  If so the above formula will be good.  But... there is always a but, I am assuming that the Stereomour can be balanced with whatever you are running it with.  The Stereomour will have a volume control internally, and it is part of the crossover.  What I'm saying is that whatever else is running, a sub maybe, will also need a volume control. 

Am I getting this right?

Jumping around, is that a picture of your dog's face/head in your avatar?  It could be from my dog's litter.  I'll post Murran's picture so you can see what I mean.

Remind me and I will send you some suggestions for upgrading when you get the bug to tweak.  As always, build stock first.  If you don't you have no idea what changes you have brought about.

[Grainger49]

Ok, painted her red/green eye, here it is:

[drewh1]

Cute Dog! I'll post another picture of my pup, here is one when he his neatly groomed - he is an Australian Shephard/Poodle mix named didjeridoo, didj for short. Great dog, smarter than I am though. I will likely ask him to do the math.

MY DIY Sub has a nice digital amp with low and high gain inputs, volume, low pass etc. I currently drive my speakers and the sub with speaker cables from the Ayre (the Ayre has no pre-amp level outputs). 

So - i want to split the output from the DAC into a 50 hz and above to the Stereomour (to relieve it from having any LF duty) and full signal to the sub (built in crossover).  My understanding is that i need a pre-amp to bring the signal to line level, than an active crossover to feed the amps. Can't/don't want to spend the money on all of that, so I am wondering if I can build a simple splitter circuit with a low pass filter on one pair of outputs. The DAC output is 2 volts in singled ended mode.

[Paul Joppa]

The difficulty is that you want the crossover to follow the gain control, so that you don't have to adjust both level controls every time you change the loudness. That's the only reason for a preamp - t use the preamp's gain control instead of the integrated.

I think the simplest solution would be to place the filter after the Stereomour's gain control. Unfortunately that means the sub output (unfiltered) has a high source impedance, so the sub's interconnect capacitance will kill some high treble for the main speakers. You can probably compromise by substituting a lower impedance control (maybe 10K?) as long as all your sources are able to drive the lower impedance.

You can build it stock (always recommended, until you know it works and have gotten everything broken in) and use the speaker-level outputs to drive the sub amp initially, then we can start a dialogue on crossover options - there are quite a few possibilities.

[drewh1]

thanks guys - I hear you "build it stock". 

I can't help thinking of all the possibilities while I am sitting here with an empty workstation and brand new soldering iron Can't tell how many times I have resisted ordering a Goldpoint and some driver tubes . . .  Hmmm, maybe I need to get a life.

[Grainger49]

Drew,

My father in law had two Australian Shepherds, one after the other.  Neither had a tail but they even looked smart.

You should always have a backup set of tubes.  The Sovtek are good tubes and extremely inexpensive.  There are all kinds of posts about upgrade 2A3 tubes here.

[drewh1]

This DIY stuff is not "instant Gratification", is it?.  I told my son this and he laughed. My kit didn't get shipped in the last batch so I am sitting on my hands. Ordering tools and thinking about paints and stains.

i love the polished metal look but don't know that I have the patience for it. Might go with a color on the transformer and chokes.  I want to make a custom Cherry hardwood base but will build it with the Ash base first, likely go with a black indian ink stain. 

Just day dreaming . . .

[4krow]

I have contemplated making a few bases for each kit, and then deciding what is best. Strange as it sounds to (being a woodworker at heart), black bases have won out more than once. Ash is a good choice, despite how hard it can be to work with. Cherry is something I have a soft spot for though(no pun intended).

[drewh1]

hey Greg - I posted this on my other thread but here is the base I settled on. Black Walnut and Cherry. Hard to see it, but the walnut has a bit of "live edge" on the front and back. It isn't finished yet, just wet but you get the idea. 

[4krow]

Gotta love it brother wood worker. Of course you realize that I have consider a new base for my quickie. In my case, I am going to try and make a design from the 40's. Maybe even something mission style, or Amish, or here we go again....good work, quite inspiring. Still wood like to see some of your other work.

[drewh1]

Well, my woodworking skills are crude, but I tend towards live edge designs anyway. Here is a coffee table I made. Got this slabe really cheap because of the knot hole. I didn't tell the guy it was my favorite feature of the piece.

[Grainger49]

   .  .  .    Got this slab really cheap because of the knot hole. I didn't tell the guy it was my favorite feature of the piece. 

This made me cackle, laugh, out loud.  Good bargaining technique.