Any DIYer s out there ?

Just to correct an error or misconception here, i am not an EE and have never been to any formal "school" for electronics. I am pretty much "self taught" via personal study while receiving "insights" from friends that are EE's or folks with their bachelors. Combine this with a LOT of hands on experience and that's where i fall into the game. As such, i am always willing to learn but am also limited in my current understanding and level of electronics knowledge. As was mentioned in previous threads though, this hasn't stopped me from working on electronics for a living or as a design consultant for over a half dozen manufacturers in my field of work.

In some ways, not being "trained" to look at things from a "conventional" textbook point of view has helped me. In other ways, my lack of formal training also puts me at a disadvantage compared to others that may have a better fundamental knowledge of what is going on in a complex circuit. Between my business partners degree and studies in electronics and my hands on experience, we have been able to work together quite advantageously though.

If i offended some EE's in one of my other posts, i do applogize. I have a great amount of respect for those that have formal educations in ANY field. It takes a LOT of patience and hard work to achieve what they have done. However, i do have to say that i have even more respect for those that make use of that knowledge and are NOT content to sit on their laurels. Push the envelope of your knowledge and skills, for your own sake. Sean
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Ehider, i think that we were posting at the same time. Thanks for sharing your insights with us. I've found pretty much the same things that you stated to be very true.

As to your comments about Zobel / impedance compensation networks, they DO have a downside though. It is called "power consumption". While the design may actually measure and sound better when "zobel'd", it will also suck more juice from the amp. If you have a limited power capacity to begin with, such as with a low powered tube or "set" amp, zobel's are NOT a good thing. As such, the engineers, designers / builders have to work with the intended market. Once this comes into consideration, you have to start thinking about MSRP, profit margins, etc... While some VERY beneficial mods can be done for pennies on the dollar, those pennies can add up VERY fast when your talking about large production runs. As such, that is one of the reasons why / how i got into this hobby. Just like you said, you can make GREAT improvements to various commercial designs with little cost or effort other than your own personal "elbow grease" and a FEW bucks here and there. Sean
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I don't know if I could be referred to as a DIYer, but I have done a bit of tube rolling and speaker modifying/designing/building in my time. Don't have the woodworking skills to build a "furniture quality" pair of speakers, but cabinet makers are always willing to help. I have not done much in the way of getting my hands dirty in the past few years, basically because of lack of time and the fact that I am satisfied with the sound I am getting from my system. I used to be of the opinion of Ehider, where things like Zobel networks, notch filters, and more components was the way to good sound. It was all impressive, and educational. Then, I started to swing back the other way. Feeling that less was more. I guess part of it was the migration to tube amplification(and its magic). Not having the current to blast through complex crossover networks, they work better with simple crossovers. And the simpler, the better. Often, the midrange driver running flat out, the tweeter only needing a capacitor and perhaps a resistor. The woofer an inductor, or maybe nothing. Parts quality being critical. As Ehider says, NorthCreek can teach us a lot regarding the effects of improving crossover parts quality. I have also come to the conclusion that wiring and solder makes a difference. To the point where I have gotten best sound from no solder at all. Rather I use a "real" crimper(NOTHING like most of us have ever seen - makes a true "cold weld") I got from Boeing Vertol's helicopter division to butt splice connections together wherever possible. Love the fact that some of us refuse to overpay for BS when we can do much, much better ourselves.

To start out, this is a great thread. The following is only my opinion on some of the above ideas. I really want to continue to exchange these ideas and discuss any and all implications. If this leads to some heated discussions, then I say GREAT. I have found that the best understanding of a topic comes from defending one's position. I hope this thread can enlighten us all to the wonderful world of DIY audio. And now my ideas.

Ehider, I can really relate to your enthusiam. I can remember when I 'discovered' the differences of crossover components. I also agree with Trelja about the simplicity of a crossover for his (tube) application. (and yes you are a DIY'er) Neither approach is fundimentally more correct than the other. My experience indicates that to get good results with a simple crossover that the drivers and cabinet must be selected VERY carefully. This may not be possiable when you are trying to modify a speaker you already own. In the latter case a zobel may be the ticket at the expense of power consumption.

On the topic of circuits, it is not always safe to just replace transistors in an amplifier with what is percieved as better units due to the possibility that you may change the stability of the amp. If the transistors are wider bandwidth, you might make your amp into a high powered oscillator and smoke your speakers. If one has access to an oscilloscope, the stability of the modified amp can be easilly checked. The bias current of the output stage will also need to be adjusted in some cases. I agree that the difference can be audible, but we must be careful! I recall where a friend of mine was told to increase the size of his power supply caps. He did, by a factor of 10, including some caps that were not in the power supply, and now the unit is dead. A lot of this DIY stuff is very easy to implement but common sense must be applied.

It is also a super cheap tweek to replace the resistor in the differential input pair with a current source. I have done it a dozen times and every time I am blown away with the improvement. Siliconix may still make a current source 'diode' that looked just like a reistor. It was simple to replace the resistor with the FET current source as long as you knew the correct value of current source to buy. I will research the availability if anyone is interested. The Aragon 8008BB already has current source transistors in the input stage but I don't know about the other models. Please let us know about the input configuration of any models you are familar with. BTW there are several easy mods for the 8008BB.

I have not heard of putting caps across the fuses. I must admit this is so simple that I feel stupid for not thinking of it. If the unit has DC power supply fuses (like the 8008BB) the caps would help to deliver transient currents to the board and ultimately to the speakers. The only place I would not put a cap is across the AC line fuse. On second thought, that might help get transient current INTO the power supply! Let's hear (see) everyones ideas on this. The cap would need to be small enough that it would not power the unit if the fuse blew, but large enough to help get transient current around the fuse. Are there any implications we need to watch out for?

Trelja, there are many people that believe the cold weld is the way to go. WBT makes an RCA that does not use solder. My many years in the aircraft industry has me very familar with the crimpers you mention. They are very pricey!

THIS IS A SUPER THREAD! Maybe we can get some of the non believers to try some of the DIY cables or some simple cap modifications and listen for the difference. Under the controlled conditions of their own system they may begin to understand what Walt Jung told me "Everything makes a difference".

I enjoy looking at schematics, quite often I get an idea or learn of a new part from looking at them. If you can get me a schematic I will be willing to try and assist anyone with a mod of their electronics. My business does take me out of town all the time but I will respond to email as fast as I can.

Chris Owen
Comm-Tronix@KScable.com (work)

I would like to thank Chris (Sqjudge) for the lead on a circuit. Thank-you!