Old electronics - Page 4 - PeachParts Mercedes-Benz Forum

samiam4 · #46 08-16-2005, 08:10 AM

Wow great stuff!!

I would suggest instead of making the CAT-5 interconnect cables buying quality cable and making them yourself. I've tried various things and find that Canard (sp?) is the maker of most studio wiring. Heck, those mic outputs are lower and much more susceptable to noise that line voltage off a preamp.

I've got 3 systems. My rocker system uses KT90 H-K citation CII in trio mode(say modification) and some homemade speakers. Really really solid amp with incredible detail. I think the orginal specs were 2hz-256 khz and 100-120 watts.

Best system is my Quad ESL speakers with either my heathkit W-5M's or UA-1's.

If you are intersted in this old gear- some of it had better output transformers than what is in current production which is it's advantage. Yes, you need some soldering skills-but it's pretty easy. These were all avaliable as kits orignally so you can get the old kit instructions and rebuild one from scratch.

http://www.quadesl.com/schematics.shtml

I think Sheldon's over all ideas are quite solid.

Michael

Kuan · #47 08-16-2005, 08:26 AM

Quote:

Originally Posted by Botnst

Resistence increases as wire diameter decreases. Why would a few ohms resistence improve the signal? Maybe increasing the resistence reduces the amount of EMF noise to the speakers?

MikeMover, does the improvement using smaller gauge occur mostly in the high-end frequencies? I'll bet it does. I'll bet that high freq is passively filtered by the narrow wire as compared to the thick wire.

Bot

Uh, nope. We're not talking resistance, we're talking impedance, a function of frequency and resistance, and EMF isn't transmitted, it's picked up. The whole system is one big antenna. We're talking RF here, a whole different set of equations.

cscmc1 · #48 08-16-2005, 10:50 AM

Quote:

Originally Posted by Whiskeydan

Anyone want a pair of Maggie MG1bs? They have been in the closet for 10 or so yrs now so, they need to go.

Cheap if you pick up north of Dallas.

Dan

Gah! I'm in IL. I'd love to have them for my tee-vee room. Damnit. I miss my old planars...

cscmc1 · #49 08-16-2005, 10:51 AM

Quote:

Originally Posted by Kuan

It's made by the pilot company. There's a Dynaco like integrated mounted in there and a Garrard table. It works pretty well. Makes Beatles records sound like Beatles records, if you know what I mean. ie., the small kick drum sounds like a small kick drum. It's OK for background listening, doesn't get loud at all. Maybe that's why.

Is it a Dyna integrated, or just dyna-like? I take it it's a Pilot version of the SCA-35 or something? I have never heard an EL-84/6BQ5 amp I didn't like. I have a pair of Knight 6BQ5 mono amps and absolutely love them with the right (read: efficient) speakers!

#50 08-16-2005, 11:17 AM

I have a set of Bertagni Geostatics (BES) that I will let go cheap. They have been in my basement for 8 years and I need the space.

cscmc1 · #51 08-16-2005, 11:25 AM

Quote:

Originally Posted by MedMech

I have a set of Bertagni Geostatics (BES) that I will let go cheap. They have been in my basement for 8 years and I need the space.

Are those the ones that have what looks like styrofoam in the panel? I have heard of them...

Lebenz · #52 08-16-2005, 11:42 AM

Quote:

Originally Posted by cscmc1

Gah! I'm in IL. I'd love to have them for my tee-vee room. Damnit. I miss my old planars...

I bought a pair from someone who advertised at this place. http://audiogon.com/

Found 'em locally. Excellent value. Some day i'll buy another set or 2 to complete the 7.1 system.

Lebenz · #53 08-16-2005, 11:42 AM

Quote:

Originally Posted by MedMech

I have a set of Bertagni Geostatics (BES) that I will let go cheap. They have been in my basement for 8 years and I need the space.

Did you ever post a pix of those? If not, would you?

cscmc1 · #54 08-16-2005, 07:36 PM

Quote:

Originally Posted by 123c

Here's a poor quality pic of my Bogen DB212

That looks like an Eico! The knobs, at least, are the same that Eico used.

#55 08-16-2005, 08:09 PM

[IMG]

[/IMG]

Here is a scan of the original manual, they are dug in deep in the storage room.

Botnst · #56 08-16-2005, 08:18 PM

Quote:

Originally Posted by Kuan

Uh, nope. We're not talking resistance, we're talking impedance, a function of frequency and resistance, and EMF isn't transmitted, it's picked up. The whole system is one big antenna. We're talking RF here, a whole different set of equations.

My poor choice of words. I think the concept still stands and I don't think we're saying different things.

The wire acts as an antenna to EMF broadcast from every device known to man and god. Usually 60hz is the big humming culprit. The smaller the wire diameter the higher the resistence and impedence. The impedence is increased by decreasing the size of the wire, I think. I don't think it is linear, is it? So anyway, I think that you can make a low pass filter of a sort by sending your signal down a narrow wire. Low freq moves relatively 'unimpeded' while high freqency gets attenuated and heats the wire.

(Impedence is also measured in ohms but is, I think, related to the work necessary to create a field perpendicular to the wire. I'm gonna read the link that MikeMover provided. I have a feeling it will make all of this moot.)

Kuan · #57 08-16-2005, 08:28 PM

Remember we're also just talking audible range. For most people that doesn't exceed 18kHz. Your CD can't reproduce above 22.05kHz.

I think you may be thinking along the lines of the skin effect and how it affects the way different frequencies travel along a conductor.

Botnst · #58 08-16-2005, 08:37 PM

Quote:

Originally Posted by mikemover

Under normal circumstances, I would not expect a smaller gauge wire to improve the signal. It could be that the conductive qualities of the different kinds of wire are so pronounced that the smaller gauge wire in question actually has LESS resistance than the larger gauge wire. This could be the result of variances in the purity of the metal (usually copper) used in the manufacture of the wires. There are also other variables, such as the terminals/jacks, and the resistance they add, and also the length of the wires in question, and possibly differences in the quality of the shielding.

Another possible scenario is this: Let's assume you have an amp that you are currently running at or near the lowest ohm rating that it is theoretically capable of. Operating this amp at high volume levels is likely to be generating excess heat, and putting strain on the power supply and other components, which will negatively affect sound quality. Changing to speaker wire that increases the resistance will reduce this strain to some degree, and could noticeably improve the sound.

A lower ohm rating allows an amp to produce more power, with all other factors being equal. All amps have a minimum ohm load capability (and a maximum as well--but exceeding this causes different problems), beyond which excessive heat will be generated, sound quality will suffer, and damage to the amplifier can eventually occur. This is why you should never run a power amp of any kind with no load (meaning with no speakers connected).

Obviously, lowering the ohms will also cause the amplifier to demand more operating current (thus the increased heat mentioned in the previous paragraph). Under heavy loads (loud peaks), this often leads to a drop in voltage from your power supply, or even from your house wiring (or car alternator/battery, if you're talking car audio). This drop in current will obviously affect sound quality, and if it is too severe, will also affect the lifespan of the amp and/or it's power supply.

Hope that makes sense.

If you want to get in to the math of how ohms relates to power, etc... here's a good page to check out:

Relationship of ohms to power output

And here's a very in-depth article about voltage loss over the length of a wire, impediance vs. resistance vs. inductance in speaker coils, etc......... This stuff gets pretty deep pretty quickly:

This will make your brain hurt.....

Mike

Mike, thanks for the links. I think you've 'outed' youself with this posting as being a bit more of an electrotechnogeek than you've previously let on.

The first article is basicly what I recalled from physics. Troglodyte that I am, I seem to save bits of unused lore in anticipation of someday using it. So far it only happens when I want to impress dogs and small children.

That second article. Whoa. That was what I was supposed to learn in AC circuits (and didn't).

Here's a paragraph that does a better job than I did in explaining the impedence with respect to wire diameter and freq.

The variation of wire impedance with frequency is less complex than that of an electro-acoustic driver because the wire does not have any acoustic nor mechanical dynamic properties associated with it. The wire impedance still varies with frequency (see Figure 4), however, as opposed to the so many ohms per foot of resistance. This means that the voltage divider ratio is frequency dependant. In other words, the dB loss due to the loudspeaker wires depends on frequency. Figure 4 and Figure 5 show the model's predicted impedance of AWG#10 conductors in non-magnetic raceway and non-magnetic cable tray, and an actual impedance measurement of the installed AWG#10 conductors in non-magnetic raceway and non-magnetic cable tray. There is a good correlation between the theoretical model used and the actual installation.

samiam4 · #59 08-16-2005, 08:56 PM

Botnst,

Wow that's pretty cool. You guys obviously know that electrolytic capacitors are also not a flat value an vary with frequency. The old audiophile trick of putting a small value cap in parallel with the large one.

I think I'm using the canard quad-4 or something like that for speaker wire. I've borrowed some flat-wire cables which were very pure copper with silver plating.. did make a difference. But I think my speaker combo of QUAD esl's finally got equipment monkey off my back.

Got to go... but I'm going to keep up with this thread!

You guys ever read the RCA radiotron book section on high fidelity!!

Michael

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