Advent experiment - mod - much better sound IMO

[Guest HarryT]

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

[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.

[Guest HarryT]

Pete,

Thanks for the confirmation. Perhaps one rainy Saturday, I'll make the 6db version and try it out also.

Harry

[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.

[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.

[Guest altair]

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

[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?

[Guest altair]

Hi Pete, as requested, here is the corrected drawing. Maybe it would be a good idea to put a sticky at the beginning of this thread to inform people.

Thanks for the idea to put a resistor across the output to match my impedance. I wouldn't have thought of it. According to this nice calculator:

http://www.calculatoredge.com/electronics/...%20resistor.htm

I'll put 220K.

I have not tried spice simulators (or speaker simulators) unfortunately. I'm not sure at all that I could design the equivalent circuit into the Advent crossover.

There are people here (and other forums) that ARE qualified to integrate this into the crossover. We just have to find them...

As I just bought the parts to replace the capacitors in my speakers, it would be perfect occasion to do the crossover mod at the same time !

I'll just wait a few days to see what happens.

Anyway, I was delighted to find your thread.

If you need me to draw some other schematic, it would be my pleasure to accomodate you.

altair

[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.

[Guest altair]

Yes Pete, that's what I was thinking, putting the crossover outside of the box for easy modding.

I will obtain the equipment to be able to check the frequency response of my speakers in my room, then it will be easy to decide what has to be adjusted.

Cheers

[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.

[jackfish]

Pete, I finished a 22K 6dB version for a friend to run between his preamp and power amp and upon listening neither he nor I can discern any difference. Is it possible I fried a component with too much heat from the soldering iron? On some of the connections I only placed a heat sink to protect the nearest component. Would that cause a lack of audible difference?

[Pete B]

Pete, I finished a 22K 6dB version for a friend to run between his preamp and power amp and upon listening neither he nor I can discern any difference. Is it possible I fried a component with too much heat from the soldering iron? On some of the connections I only placed a heat sink to protect the nearest component. Would that cause a lack of audible difference?

I doubt that anything is fried, more likely the capacitor to ground is

off by a factor of 10, or and many people seem to have done this, it

is in backwards. The RC network to ground is the output of the BSC

and should go to the input of the power amp. You could also check

the resistor values with an ohm meter.

What are the pre and power amps?

Sorry for the delay, I've not been checking in here much as the place

is not very active.

[Pete B]

Just had a thought, it would be interesting to compare Advents

with BSC to DQ-10s, however I don't have a pair of DQ-10s.

Perhaps someone with Advents does?

[Pete B]

Started a new thread on how to build the BSC:

http://www.audiokarma.org/forums/showthread.php?t=647441

[JKent]

Pete,

I think the new thread was a good idea. These long threads get a little disorganized. So I'm not going to go muck up your pristine new thread, but wanted to post a comment:

I built the 4.7K version some time back, but did not keep the OLAs for long. To my ears they did not measure up to the AR-2ax's I was using at the time. But I do use it. It's in an External Processor loop so it can be easily switched in and out. What I find is that some recordings seem to benefit from the BSC while others sound better without.

The current speakers are AR-3a with MicroStatic supertweeters and a VMPS sub (crossed over at 30Hz). Source is usually a Tivoli CD player. Other equipment includes DB Systems pre-amp and tone controls, an AR-SRC remote (that's where the EPL is) and an Adcom 555/II power amp.

I haven't kept careful track of when the BSC is in or out of the system but IIRC I usually keep it out for classical and jazz recordings but switch it in for "some" rock or popular recordings. Does that make sense?

Anyway, it's a fun little gadget.

-Kent

[Pete B]

Hmm, well Kent, I really dislike AR-2aXs there is a lot that I could say about them.

It is probably possible to adjust the pots on the 3a so that you do not need BSC.

Yes, for me it is usually LP that usually needs BSC from what I hear and I'm sure some other

recordings also.

Kent, we (we is me and everyone I demo them to) love the $2400/pr reference speakers that I

use and it was very hard to tell when it was the Advents with BSC or the reference in a level

matched A/B comparison. My reference is rated as +/-1.5 dB from 36 to 20 KHz and was tested

at the NRC - they are that good.

What else can I say?

[kavalski]

On 10/12/2004 at 5:51 AM, Guest Ken Perkins said:

I posted this yestersay on the Parts Express forum. It's a performance upgrade for the original Advent Loudspeaker. It does not address the baffle step but it does improve detail resolution and imaging and gives them that "disappearing" quality mentioned earlier that they lack stock. I've compared my modification before and after and it will not affect or alter the original voicing.

Also, I highly recommend the foam surround replacements from www.rssound.com as they have the correct 17mm wide roll like the woofers originally had. Most of the refoams I've seen use a 14mm wide roll and this will restrict xmax and the dynamic range of the woofer.

http://www.pesupport.com/cgi-bin/config.pl?read=189156

Hey Ken:

 

This mod is no longer published at that web address.

Any chance you could email the details to me or republish somewhere public?

 

My email is jim@kavalskigarden.com

I am running a stacked advent system and wanting to work on the speakers.

 

Thanks,

 

Jim

[Guido57]

I too would like to see those details but since it was posted by a guest, Guest Ken Perkins, it's quite possible he has not been to this forum since his original post.

I'd like to note that at least one company has presented a replacement tweeter for the Legacy and other later Advent as a fitting drop in replacement for the fried egg tweeter in the Large Advents with no crossover modifications.  I find this to be highly dubious.

[Pete B]

I remember looking at Ken's mod but I have very little memory of it, I think it was simple perhaps

film caps but that is just a guess.

@kavalski  Do you have OLA or NLA s and how many watts?

[ajfink]

Sidenote - I recently mucked around with how my system is cabled and swapped my BSC box out and then back in just for a perceptual refresher.  The BSC makes a world of difference.  Advents aren't ever going to really disappear into the soundstage, but the BSC does a damn fine job of taking them in that direction.  Highly recommend.