[Folsom]

Here my design for my passive pre-amplifier. It does have two active crossovers in it to make a high pass for the TB's and a low pass for subwoofer. I also threw in a volume control, source selector, and gain controls for each channel of the high pass, and one for the low pass. Those are important because I do not plan on a volume control on my amplifier, just an on and off switch. I might take out the subwoofer gain as the plate amplifier has one, but it would be convenient to have one on hand and not under the desk.

I currently have the TB W3-871's, which I plan to switch over to John "Zaph" Krutke's box 3 design with notch filter.

The subwoofer will be a TB W6-1139SG ported to 34 Hz, in a .5 cubic foot box. Dimensions are, 10.6 W, 15.4 H, 7.8 D, with 1 inch diameter port by three inches long, Powered by a Dayton 25wRMS plate amplifier. It gives a nice flat output, and has -3db roll off at 30 Hz. Not bad for a 6.5 inch woofer huh?  

The Hagerman bugle may come a bit later.... I plan to have a separate power supply from the bugle itself because of the design of the bugle. I can also run it on 9v batteries if I need too.

The crossovers and power supply are made by Marchand Electronics Inc. They are kits, as well as the amplifier by Tubes and More. Chassis choices are undetermined.





Sorry about the sideway image, photobucket would not take it horizontally, at least at a decent size.

[Folsom]

I thought some one would have at least some thing to say, that I never thought of or some thing. I know the drawing is not real good but you can understand what is going on....

[Watson]

That looks like a fine setup.  I've heard the 8 watt tube amp you're referring to and I liked it.  (I'm not as big a fan of the TB speakers, but I was using them fullrange without a crossover.  Zaph's network probably evens out the sound, and using them with a proper high-pass crossover should clean up the sound substantially.)  You might be confusing people when you refer to a passive preamp; with the pot hanging in front of the Marchand boards what you've got there is an active preamp.  When you build the tube amp, I would leave the volume control in for versatility.  (You may want to use it as an integrated amp in an office or bedroom rig someday.)  Don't believe the hype about the extra pot coloring the sound; if you turn it all the way up, as you'll want to do in the configuration you describe, the pot turns into essentially an open circuit.

[Folsom]

That looks like a fine setup.  I've heard the 8 watt tube amp you're referring to and I liked it.  (I'm not as big a fan of the TB speakers, but I was using them fullrange without a crossover.  Zaph's network probably evens out the sound, and using them with a proper high-pass crossover should clean up the sound substantially.)  You might be confusing people when you refer to a passive preamp; with the pot hanging in front of the Marchand boards what you've got there is an active preamp.  When you build the ...

Whew I feel good that some one can tell me I am in the right direction.

Well it is passive in the meaning that nothing is being amplified or capable of being amplified. Right now I love my TB's, and I feel the tube amplifier which will have about the same amount of distortion as my Rotel, as it is old, but good enough, will add some warmth.

The TB's sound best at very low listening levels. However it is hard to just listen, or have an environment, or be close enough to them and have them situated, so you can tell. When you do though, they are magical, I hope new boxes, notch filter, and high pass filters will bring some of this magic to a higher listening level. However I am some what skeptical of my setup, as Vinyl sounds just breathe taking through the Rotel, at any volume level. Well of course the music is different, no huge emphasis on lower notes, and the recordings focus on the singer’s voice rather then instruments, which is where the TB’s function well compared to bass. I have to say though one thing the TB’s capture more then any thing is the piano, I can not wait to hear my piano vinyl I found at a thrift shop! All in all the TB’s for the price have created a better sound then any piece of commercial audio I have ever heard before, which unfortunately is most of what I have heard. The biggest comparable thing I have is my Sennheiser HD590’s, with screens removed and powered by the same Rotel. The sound from the TB’s is truer, but lacks in the kick bass and some bass guitar notes. Truth be told I kind of like a small lack in some instruments because it reminds me of Vinyl a little. The TB’s with Vinyl, Creedence Clearwater Revival, can pretty much bring a tear to my eye. I think part of it is that I saw Revisited in concert with two of the original members.

John recommends and entirely different speaker now, but I would not put any thing past the TB’s. The speaker he recommends also needs a crossover to function basically, on his note, while the TB’s play fine with nothing. I however once in awhile pick up on the TB’s natural peak with a few songs and agree that it is a little harsh, hence the notch filter. Plus at 8wRMS I really have no interest in speakers with sensitivity any lower. John also hates tube amplifiers so he has never had a little distortion to bring some warmth to his TB’s, this will be some thing new.

My biggest worry is the quality of the crossovers…. I will venture to say they will give less noise and distortion then the pots and mini circuits for the bass and treble control on my Rotel. I however can not help but worry a little; I wish I could go with a more expensive design of theirs just out of a little freight. I do wonder if they use some rather expensive parts in their kits, I would bet they do, and the need for them is not there. A PCB and parts list would be nice, that way I could perhaps piece them together for considerable cheaper. I think a few too many manufactures go a little overboard on the parts. That and they have to turn a profit so the parts cost a little extra. My biggest fears are finding some good pots and maybe some step pots (what are they called?) for a decent price, I can see them adding up to more then the rest of components. If I had it my way there would not be one pot, just those stepped ones, what are their names?

I think I might do some soldering with the internal crossovers….. I would prefer more solder less pressed plates via screws. I will see how much room on the PCB board there is for that.

Any comments on the run distance for the internal wires of the preamp? Should I try to keep them as short as possible after the inputs? Should that be a big concern… The crossovers will power the out all over again as they are active. I just figure keeping the RCA cable running distances between amplification, to a three foot / one meter distance would be fairly optimal.

I think I might just put an optional pot placement on the amplifier, or an internal adjustable screw type pot adjuster. I was thinking of making the amplifier look pretty cool, tubes out the top, transformers out the top. You know, classic tube amplifier look, glowing and showing. I figured one LED for the power switch would make it pretty elusive and sexy, I like that look, with wood. Oh man, what wood am I going to use for the amplifier and preamplifier, this never cross my mind before…. I like wood. A wood aluminum combination is also attractive, but not just a faceplate, way to retro and Rotel haha!

[Gordy]

Phil Marchand's crossover's are available as empty PCB's as well, should you want to populate them as you see fit.  The majority of the parts he includes are Xicon,  nice  parts and standard in many components.  His power supply caps are Nichicon SMH electrolitics, again, very nice standards of the industry.  Plenty of room for improvement should you decide to upgrade in the future... especially the coupling caps.  One thing you should definitely think about is ordering the upgraded 2134 opamps, a big improvement over the standard supplied opamps!  

Sounds to me like a really fun project, enjoy  

[Folsom]

Phil Marchand's crossover's are available as empty PCB's as well, should you want to populate them as you see fit.  The majority of the parts he includes are Xicon,  nice  parts and standard in many components.  His power supply caps are Nichicon SMH electrolitics, again, very nice standards of the industry.  Plenty of room for improvement should you decide to upgrade in the future... especially the coupling caps.  One thing you should definitely think about is ordering the upgraded 2134 opamps, a big impro ...

Well for the ease of ordering things I might as well stay with the kit. I however think I might just order the 2134 opamps because I can. Perhaps the coupling capacitors as well. I really do not want to tear this thing open a lot.

I am debating using the same power supply on the preamplifier as for the Bugle..... They look to be similiar, just the Marchand's is bigger. I e-mailed Phil about it. If they are I might just make a power jack or two from the preamplifier so in the future other things can be plugged into it, that otherwise would need their own power supply. I did, any ways, plan on having the Bugle power supply seperate from the Bugle, so this should work out if possible.