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Advent BSC switch?


kehern15

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Hello all,

I was going to build a BSC for my OLAs, and right before I clicked the "Buy" button for the components, I realized something. This device will be going between my DAC and power amp, the latter is hooked up to my Advents and Overnight Sensations (the amp has an A/B speaker selection). I then realized that this BSC will also be effecting the OS speakers!

How would I go about making a BSC with a built in switch, so that I can bypass it when listening to my OS, and activate it for the Advents? Or, alternatively, maybe I can put the BSC between the amp and speakers?

I have no electronics knowledge, sorry for my ignorance!

-Keher

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You can't put it between the amp and speakers because that's way too much current and will burn up the BSC.

All you really need to do is put a wire between the input to the device and the output. Now, cut that wire and put a switch between the two ends. When you close the switch, you will be bypassing the BSC cicuit. Signals will go right from the input out the output without any of the internal components having any effect.

Doug

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Keher,

I took the illustration provided by member Jackfish in Post #140 (!!) here http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=2692&page=7

and added the switch Doug describes.

If you're ordering from PE you could use this http://www.parts-express.com/dpst-light-duty-toggle-switch--060-544

-Kent

EDIT: See Pete's post later in this thread for version with DPDT switch, which would be better

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Thanks guys, seems really easy to do. I'll be buying my stuff from Radioshack.

There seem to be a few switches there, rated at different voltages/amps. And some are "quick" contacts and others are "slow". What is the difference/more appropriate for this application?

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Usually, switches aren't designated "quick" or "slow" contacts. They are usually designated momentary, which means the contacts are only closed while you hold the button in or dial in one position, or maintained, which means the contacts stay in the position they are thrown, either closed or open, until the switch is operated again. A common light switch is an example of the latter and a doorbell button is an example of the former.

You, of course, want a double pole (essentially two switches in one body), single throw (on-off) maintained contact switch.

Are you thinking of fuses? They are usually designated fast blow or slow blow.

Doug

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Hm, so what is the difference between these two switches? The first line of the description is what I'm talking about, regarding the break "speed"

http://www.radioshack.com/nte54-004-15a-bat-handle-toggle-switch/55050496.html#q=dpst&start=7

http://www.radioshack.com/nte54-055-16a-bat-handle-toggle-switch/55050511.html#q=dpst&start=6

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.... or this from Parts Express - - a simple DPST switch for just over a buck, rated up to 4 amps. Should be fine, but just to be sure, I'd suggest a quick phone chat with a service rep before ordering. Kent's much better at this process than me, but those websites at Digi and Mouser just drive me crazy - - I never know how to find what I want.

http://www.parts-express.com/dpst-light-duty-toggle-switch--060-544

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ra,

That's the same switch I linked to in Post #3 :D

And I found Mouser & DigiKey's sites confusing at first but practice makes perfect.

Keher,

If you give us a parts list I can give you the corresponding Mouser or DigiKey parts.

-Kent

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JKent, that would be most helpful and kind of you! I wasn't planning on buying my items from Radioshack, but I had no idea where to start at Mouser, as they have a massive catalog and I was unsure of what parts I needed for this BSC.

1. A small plastic housing box

2. Set of RCA plugs

3. And for the important parts:

2.2K Version @ 5dB

R1 - 2.2K

R2 - 2.6K

C1 - .01 uF

C2 - .12 uF

Mylar capicitors

Metal film resistors

I am also a bit confused as to the 2.2K version and the 4.7K version? I will be using this in between my DAC (Behringer UCA202) and my amp (Audiosource AMP-100). The DAC has an output impedance of 400 ohms.

If anybody could help, that would be most kind. I don't believe I am missing anything else on my list!

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Keher

Here is a list of Digikey parts and a list of Mouser parts. I like the Mouser ones a little more but either should be good.

I don't know the difference between the 2.2K and 4.7K versions--this is Pete's thing so ask him. Also, I used 1/2 watt to 3/4 watt resistors but maybe double-check with Pete on that.

Hope there are no goofs here ;)

-Kent

edit: there ARE goofs. Sorry!

The Mouser list has 1.2k and 1.6k resistors. Should be 2.2 and 2.6

Here's a 2.2K 1/2w 1% http://www.mouser.com/ProductDetail/Vishay-BC-Components/SFR25H0002201FR500/?qs=sGAEpiMZZMu61qfTUdNhG%2f4r7Iw6CIkyIFstF2iz8BU%3d

And here's a 2.61K 1/2w 1% http://www.mouser.com/ProductDetail/Vishay/RN65D2611FB14/?qs=gD%2fY%2f%252btXDbLBFyJ46%252bG1Ng%3d%3d

Sorry if anyone ordered the wrong thing based on my list.

I'm deleting the Mouser list and will post a corrected one. See post #23.

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Awesome, you are the best! I tried to PM him, but he seems very busy and is unable to respond. Does anyone else have any insight on what is appropriate for me?

And those resistor wattages are fine, forgot to mention that in my post.

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Let me ask you, since you are using the LAs and OSs on the A/B switch of the amp

would you prefer to have a speaker level version of the BSC? I tried one way back

but never published it.

I also seem to remember reading that you like your OSs far more than the Advents

is that still true?

If it is, I'd suggest that you try the loader BSC at line level, then if you think that the

Advents are worth keeping is it worth putting about $50 into a speaker level BSC?

The loaner is out at the moment but I can have it sent to you next if you'd like to

try it.

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A speaker level would be easier for me, yes. $50 is a bit steep for me right now (college student), but I would be curious to see the schematic, and in a few weeks when I've saved up enough, I will probably build it. Most likely after I try making the BSC, probably with the switch, as I'm using my Advents 90% of the time, and the OS's later at night as to not disturb the neighbors with the large bass presence of the Advents.

Ah funny story...I liked the OS's because I very embarrassingly had my Advents wired out of phase. :rolleyes: After wiring them correctly and listening for a few weeks, I've grown to prefer the Advents quite a lot. So I don't mind investing in them.

I would like to try the loaner if possible. Shoot me a PM when you get it back, I can also better realize what dB of compensation I want.

P.S. For the BSC, which version would be appropriate for me, the 2.2K or 4.7K version? My DAC output impedance is 400 Ohms, and I could not find the input impudence of my amp. The sensitivity of the input is 1.5 Vrms if that helps at all.

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That all makes sense, let me see if the current BSC user is done and I'll have him send it

to you, PM me your mailing info.

2.2K is correct given that you're going into a SS power amp.

It is hard to give up the excellent Advent bass once you're spoiled by it.

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And by the way the old very common green or red mylar film caps are fine for the

line level BSC. You can use better film types but I do not suggest it, try to get them

at a better price RS is very high just showing the picture here:

http://www.radioshack.com/capacitors#prefn1=productType&prefv1=Polyester%20film%20capacitors

Resistors are not critical 1/2 W are easier to work with but 1/4 W is fine, old carbons

that are in spec are fine, metal film types are what I would use 5% tolerance or better.

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btw

IF you have a Rat Shack nearby and IF they have any project boxes you might want to go and look and pick out one you like. The one I picked out of the Mouser catalog is fine. I used a very small box when I built my BSC. Here's what's in the RS catalog: http://www.radioshack.com/search?q=project+enclosure#start=0&q=project%20enclosure&sz=12&srule=Price-low-high

The 1st one should be fine.

The Mouser order I show above includes the least-expensive resistors and caps in the specified values.

-Kent

OOPS! I just found a mistake. I specified Switchcraft RCA jacks because they are high quality and made in the USA but I noticed there is one gold plated and one nickel.

Pick the jacks from here: http://www.mouser.com/Connectors/Audio-Video-Connectors/RCA-Phono-Connectors/_/N-778cxZscv7?P=1z0z2wqZ1z0z24wZ1z0z2xaZ1yzv7vuZ1z0z2qrZ1yzvpvhZ1z0yy6bZ1yzvpvd&Keyword=rca+jack&Ns=Pricing|0&FS=True

Maybe go with the Keystone #534-580 (red) and 534-576 (black). Or if you want gold plating the Rean/Neutrik jacks are nice: 568-NYS367-0 and 568-NYS36.

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Thanks Pete, PM has been sent.

Yeah, I'm having a lot of difficulty getting over the bass of those Advents. It is just very balanced, clean, and incredibly deep. It has become my new reference point, even in comparison for headphones. Hard to not love it!

Thanks, I'll probably get everything off Mouser once I have tried the BSC and settled on the dB level of compensation I would like. Was just using Radioshack as I was a bit overwhelmed with the selection at Mouser, not knowing much about electronics made it a bit much. But JKent helped, thanks!

I'll be sure to look at those JKent, thanks again!

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I forwarded your address, but told him to keep it the weekend so he could finish his listening.

Please offer your impressions good or bad once you get it.

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Awesome, thanks. I'll post my thoughts in this thread after I give it a listen. I'm quite curious if I am going to like it, as I've grown very accustomed to the Advents stock sound. But more midrange and less tweeter harshness does seem good!

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Kent your Mouser order list has a thick film SMD resistor, that is a surface mount part,

You should just use the same metal film type that you speced for the other one.

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Thanks Pete.

When I looked it over I found TWO glaring mistakes. The Mouser order showed 1.2K and 1.6K resistors. Should have been 2.2K and 2.6K

My apologies to anyone who bought the wrong thing based on these bonehead goofs!

Here's a corrected (I hope) Mouser list.

Kent

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Pete, I understand what your BSC design does to attenuate the HF portion of the FR. If you recall, I ran some tests on an advent using a BSC circuit I built and posted them here in your long BSC thread.

What's bothering me at the moment is how does the BSC circuit (paralleled coil and resistor) in series with the woofer suggested by some authors. How does that circuit affect the woofer's response in order for it to compensate for baffle step? Does it somehow boost the woofer's response below 300 hz?

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Pete, I understand what your BSC design does to attenuate the HF portion of the FR. If you recall, I ran some tests on an advent using a BSC circuit I built and posted them here in your long BSC thread.

What's bothering me at the moment is how does the BSC circuit (paralleled coil and resistor) in series with the woofer suggested by some authors. How does that circuit affect the woofer's response in order for it to compensate for baffle step? Does it somehow boost the woofer's response below 300 hz?

Hi Carl, What is typically done in the usual 2way design with BSC is to make the woofer inductor much larger, in fact the value that I use as a start is 1 mH for a 4 ohm system and 2 mH for an 8 ohm system to get in the ball park for about 6 dB of BSC. If the woofer was a resistive load this would simply be a first order, 6dB/oct rolloff, but the woofer is inductive (usually) so the load impedance rises causing the crossover inductor to level off forming more of a shelf response. Then usually I'll add a cap and resistor to have that rolloff transition to 2nd order and just size the cap to put the XO where I want it and the resistor to adjust the Q or shape. This is what I did in the Minimus 7 upgrade and it is what is done in _many_ commercial mini monitors and in many of Zaph's and Bagby's designs. Now, if the woofer is low inductance or you already have a crossover inside the speaker and want to add BSC outside, then you add the inductor and you will get a 6 dB/oct rolloff and then the resistor turns it into a shelf since it will always pass some signal independent of frequency. A smaller resistor gives less BSC and as it goes to zero it simply shorts the inductor obviously.

Sometimes the woofer impedance just doesn't work out but you can usually get it to work with the more complicated configuration of the LR for baffle step followed by the rest of the woofer crossover.

Not sure if I was clear here.

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