142 replies to this topic

[MartyKuest]

Don't know exactly where to put this little gem. Don't think it is worth a new topic.

Have been so pleased with my advents since I built the bsc, wouldn't be inclined to exhange them for anything. Of course, they are and remain (until now) the unheralded bargain of the 21st century. But their auction prices have been creeping upward.

See the recent A-4 result on Ebay. Item number:300254526569. Granted that the presentation was way above average, so too was the result. At first blush, the sale price of $617.67 plus shipping seems extreme. But in truth, I guess the adjusted new price of a new pair in 1978 would be around $800. Pretty interesting.

Once again, thanks Pete for all your good work!

Marty

[Pete B]

Don't know exactly where to put this little gem. Don't think it is worth a new topic.

Have been so pleased with my advents since I built the bsc, wouldn't be inclined to exhange them for anything. Of course, they are and remain (until now) the unheralded bargain of the 21st century. But their auction prices have been creeping upward.

See the recent A-4 result on Ebay. Item number:300254526569. Granted that the presentation was way above average, so too was the result. At first blush, the sale price of $617.67 plus shipping seems extreme. But in truth, I guess the adjusted new price of a new pair in 1978 would be around $800. Pretty interesting.

Once again, thanks Pete for all your good work!

Marty

Thanks Marty, I appreciate the positive feedback.

I should probably mention that it was a surprise to me that the BSC worked so well,
that is why I posted it in the first place. Anyway, thanks again.

[Pete B]

I just tried the BSC circuit with a pair of New Large Advents that I bought a couple of weeks ago. I used the RL=47K, 4db version with the tweeter switch at normal and the circuit installed into the tape monitor loop in a Marantz 1070 integrated amp. The speakers sound so much better. I was kind of disappointed when I first heard the speakers because I thought they sounded rather harsh/edgy. Luckily, I found this forum and this thread. The speakers were intended for my secondary "basement" system. Now I find myself spending more time in the basement. Thanks to you and all the contributors to this very interesting discussion.

I do have one question. Will this version of the circuit also work if installed between a pre-amp and a power amp? If I have to change it, what specifications do I have to look for in order to decide which RL version I need to use?

Thanks,

Harry

Hi Harry, thanks for your comments!

The input impedance of the power amp or tape monitor loop is what matters.
The 47K version was intended for tube equipment that usually has an input
impedance around 470K or 1M ohm.

I was looking for an Rin for about 10X or more of the BSC circuit.
Tape loops are often 47 - 100K Zin, so the 4.7K BSC would be correct.
Solid state power amps are often 22K Zin, and the 2.2 K BSC should be used.

The BSC boost will be way off if you use the 47K version with most SS gear,
did you mean 4.7K?

Post #41 here has the values, if you need to change it:
http://www.classicsp...r...ost&p=66294

[Pete B]

Pete,

I do have a solid state integrated amp (Marantz 1070) and I am using the 4.7K version (made for RL=47k) in its tape loop. This sounds very good, much better than the comparison signal without the BSC. I am not sure if I understand you correctly that I should use the 2.2 k version in this tape loop or only if I am going to use the BSC between a pre-amp and a solid state power amp.

Thanks.

Harry

That is correct, use the 2.2K version between the pre-amp and solid state power amp,
just keep in mind that this assumes a power amp Zin of about 22K.
You could check the power amp input Z and if around 22K then use the 2.2K version.
If 47K or higher then use the 4.7 K version.

[bikenut]

Hello Pete:
It's been so long since I've wanted to use the BSC, but I've finally built it this weekend for my New Large Advent speakers.
I went with the 4.7K version and 6dB.
I have it on the tape in and out on my Sansui amp, and the improvement was well worth it.
I noticed an improvement with a single pair running and in the stacked setup.
Thanks so much for all your efforts on this.

I now want to build the single toggle switch version with 4dB, 5dB and 6dB for comparison, then settle on the one I like best.
I just reviewed your earlier post and your notes and I have a question before I proceed.

The values you listed in post #112 for the single toggle version don't match either of the 2.2 or 4.7k version values.
Is this an error, or is it correct and the values for resistors and caps change because of the design for the single toggle version?

Your comments below on the toggle switch version:
Build it for 4dB of BSC, which has a shunt R of 7.5K, C of .047 uF
One switch side gets 22K in series with .01 uF to ground, one for R another for L, this is +5 dB,
Other switch side gets 10 K and .022 uF to ground, one for R another for L, this is +6 dB,
Center off pos is +4 dB.
HF boost just switches in the .0047 uF cap.

4.7K Version:
R1 = 4.7 K, C1 = .0047
        C2    R2
4dB .047   7.5K
5dB .056   5.6K
6dB .068   4.3K <– this is what I currently went with.

Which values should I go with for the 5dB and 6dB resistors and caps?
I see the 4dB values are the same for both versions.

Thanks again, Bill

[Pete B]

Hello Pete:
It's been so long since I've wanted to use the BSC, but I've finally built it this weekend for my New Large Advent speakers.
I went with the 4.7K version and 6dB.
I have it on the tape in and out on my Sansui amp, and the improvement was well worth it.
I noticed an improvement with a single pair running and in the stacked setup.
Thanks so much for all your efforts on this.

I now want to build the single toggle switch version with 4dB, 5dB and 6dB for comparison, then settle on the one I like best.
I just reviewed your earlier post and your notes and I have a question before I proceed.

The values you listed in post #112 for the single toggle version don't match either of the 2.2 or 4.7k version values.
Is this an error, or is it correct and the values for resistors and caps change because of the design for the single toggle version?

Your comments below on the toggle switch version:
Build it for 4dB of BSC, which has a shunt R of 7.5K, C of .047 uF
One switch side gets 22K in series with .01 uF to ground, one for R another for L, this is +5 dB,
Other switch side gets 10 K and .022 uF to ground, one for R another for L, this is +6 dB,
Center off pos is +4 dB.
HF boost just switches in the .0047 uF cap.

4.7K Version:
R1 = 4.7 K, C1 = .0047
C2 R2
4dB .047 7.5K
5dB .056 5.6K
6dB .068 4.3K <– this is what I currently went with.

Which values should I go with for the 5dB and 6dB resistors and caps?
I see the 4dB values are the same for both versions.

Thanks again, Bill

Hi Bill,

Yes, you're right that the values are not in the table because the switch puts them in
parallel with the 4dB components and they essentially just add more BSC. I determined
them through LT-Spice simulation in comparision to the table values. I don't remember
if it was the 4.7K version that I built or the 2.2 but based on the table values you show
there the 7.5K anmd .047uF are the 4.7K version. So that is how you'd build it.

Just to be clear, the switch is a 3 position center off DPDT switch. You build a 4dB design
which is always in circuit, then the switch center off is 4dB, one side adds the RC to bring
it up to 5dB, the other side to 6dB.
5 dB: 22K in series with .01 uF to ground for right and left channels
6 dB: 10K in series with .022 uF to ground for right and left channels

I can determine other values if you prefer less, say 3, 2, or 1 as a min, just let me know.
You could also use a 5 position selector that I believe is available at radio shack, if you
want more options.

Best regards!

[bikenut]

Hi Bill,

Yes, you're right that the values are not in the table because the switch puts them in
parallel with the 4dB components and they essentially just add more BSC.  I determined
them through LT-Spice simulation in comparision to the table values.  I don't remember
if it was the 4.7K version that I built or the 2.2 but based on the table values you show
there the 7.5K anmd .047uF are the 4.7K version.  So that is how you'd build it.

Just to be clear, the switch is a 3 position center off DPDT switch.  You build a 4dB design
which is always in circuit, then the switch center off is 4dB, one side adds the RC to bring
it up to 5dB, the other side to 6dB.
5 dB:  22K in series with .01 uF to ground for right and left channels
6 dB: 10K in series with .022 uF to ground for right and left channels

I can determine other values if you prefer less, say 3, 2, or 1 as a min, just let me know.
You could also use a 5 position selector that I believe is available at radio shack, if you
want more options.

Best regards!

Pete, thanks for the confirmation of the toggle switch resistors & cap values.
When you have the time, I would welcome the values for 1, 2, and 3dB.
I may end up going with a 5 position switch for the heck of it, something to do.
Thanks again, Bill

[Pete B]

Pete, thanks for the confirmation of the toggle switch resistors & cap values.
When you have the time, I would welcome the values for 1, 2, and 3dB.
I may end up going with a 5 position switch for the heck of it, something to do.
Thanks again, Bill

Just remembered that the only reason for the parallel arrangement is that the
center off switch does not allow an RC to be switched in when in the center off
position. A 5 pos selector switch doesn't have this problem - so you just build
it with the values in the table.

Best Regards!

[Carlspeak]

I built one of P. Basel's BSC designs and tested it on a NLA. The parts are listed on post #103 in this thread. After first finding I had the inputs and outputs reversed with no descernable effect, I consulted with Pete and found I had them backwards. Upon switching them around, Pete's claimed effect presented itself in spades. See attached resp. plots showing without BSC (blue line) and with (red line) the BSC connected to my Insignia receiver's preamp out to amp input connections.

Consider this an independent validation of Pete's BSC design.

Attached Thumbnails

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[Pete B]

I built one of P. Basel's BSC designs and tested it on a NLA. The parts are listed on post #103 in this thread. After first finding I had the inputs and outputs reversed with no descernable effect, I consulted with Pete and found I had them backwards. Upon switching them around, Pete's claimed effect presented itself in spades. See attached resp. plots showing without BSC (blue line) and with (red line) the BSC connected to my Insignia receiver's preamp out to amp input connections.

Consider this an independent validation of Pete's BSC design.

Thanks for the confirmation Carl.
People should note that the depression around 2 KHz actually helps the
sound IMO. Still, overall the response is flatter, and that is a rather
expanded scale that Carl used.

I'd also like to just mention that I built the BSC for AR-2ax's, and tried it
with the Advents just as an experiment. It was purely an accident that it
worked so well but not surprising if the conclusion is that the Advents need
BSC.

[Pete B]

Hi Pete, I tried you mod with great success !
This should be part of every system running Advents.

I built the 4.7K, 4dB version. However my NAD 214 power amp's input impedance is listed as 60K, so I'm a bit off with the values.
I was wondering if it would be possible to integrate this circuit into the speakers crossovers themselves. That way, there would not be any need for different versions.
That might be more complicated to calculate however, and I'm not qualified to do the design. It will be more expensive to build, of course.
What do you think ?

Another option would be to build an active filter, with an op-amp buffer so it can be plugged into anything without concern to impedance matching.

By the way, I've drawn a schematic of your circuit, taken from your ascii drawing in post #41. Note the reversed IN-OUT captions ! They are in conformity to the ascii drawing.
Maybe it would be appropriate to post a corrected version, so beginners without electronics knowledge could easily manage the build.

Thanks for everything,

altair

Ah! So that is why several people put the BSC in backwards!
My schematic in post 41 is correct when all the spaces in the
diagram are left in, the board removed them however, and
made it look like the shunt RC network to ground goes at the
input. I made note of this when I first posted it when this thread
was on the old forum board, and I think that the spaces were
lost again in moving to the new board.
Yes, your diagram is backwards, and please correct it.

The 4.7K version is designed for a 47K ohm load, your is 60K
so the simple thing is to just put a resistor across the output
of the BSC so that the combined parallel resistance is about
47K.

Yes, those are all good possiblities, passive at the speaker,
with an OP amp - however I wanted to keep it simple.

Passive at the speaker has some issue with the complex
impedance of the speaker load - it can be done. Also, the
LA, and New LA have very different impedances at high
frequencies.

Have you ever used a SPICE circuit simulator? Or even better
a speaker system simulator?

[Pete B]

You have to be a moderator to make a sticky and I think we have
a new moderator who might have the time to do it. There have been
a few other suggestions also.

I have a rough new passive crossover that I did with my son one
afternoon. It sounds very good, however I've not done full testing
and verification so I'm not going to publish it. Consider the controversy
this little circuit caused.

I'd suggest that you add Bi-amp posts or an input cup and then you can
try an external BSC circuit and have a bit more flexibility with the independent
woofer and tweeter connections. You could even outboard the crossover.

[jackfish]

For some reason the picture I posted of the circuit in diagram form no longer shows. Here it is again, attached.

I have to build a new BSC for between a preamp and amp as a friend needs one for his system.

Attached Thumbnails

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