[Jens]

Ray,

I fully understand that you cannot see what is going on, however, I hope my descriptions make it fairlly clear what what I am doing

Please feel free to ask away, if anything isn't clear!

Hugh,

I know about the Zobel corrections, and I will try with and without. For the tweeter, which will be replaced with the newest Scan-Speak beryllium dome tweeter that has a neodymium magnet system, there will probably not be much to gain. The current micdrange driver will be replaced with an Accuton ceramic driver (weighing around 3.5 kilos!). For this driver, there might be something to be had. However, this driver will be operating in an enclosure with an 'acoustic valve' (a dampened opening in the enclosure, which evens out the impedance peak), so the effect may be cancelled out by the passive components that are introduced. However, I will try it out!

For the bass drivers - I don't know if there is anything to be had there ... 

Cheers,

Jens

[guest1632]

Ray,

I fully understand that you cannot see what is going on, however, I hope my descriptions make it fairlly clear what what I am doing

Please feel free to ask away, if anything isn't clear!

Hugh,

I know about the Zobel corrections, and I will try with and without. For the tweeter, which will be replaced with the newest Scan-Speak beryllium dome tweeter that has a neodymium magnet system, there will probably not be much to gain. The current micdrange driver will be replaced with an Accuton ceramic driver (weighing around 3.5 kilos!). For this driver, there might be something to be had. However, this driver will be operating in an enclosure with an 'acoustic valve' (a dampened opening in the enclosure, which evens out the impedance peak), so the effect may be cancelled out by the passive components that are introduced. However, I will try it out!

For the bass drivers - I don't know if there is anything to be had there ... 

Cheers,

Jens

Hi Jens,

The only possible issue I see now is your IC length between your power amps and preamp. Depending on the cable being used, you could have capacitance issues, but that a different topic for a different circle. you probably already have that all figured out.

Happy listening when you get it all together.

Ray Bronk

[Jens]

Hi Ray,

I make my own interconnects. These are twisted to minimize capacitance issues. Also, the x-over inputs are designed with long interconnects in mind.

I will need to shield the interconnects, but that is not an issue 

Cheers,

Jens

[andyr]

Hi Ray,

I make my own interconnects. These are twisted to minimize capacitance issues. Also, the x-over inputs are designed with long interconnects in mind.

I will need to shield the interconnects, but that is not an issue 

Cheers,

Jens

With respect, Jens, if you are twisting 'hot' & 'ground' wires of your IC together, you are generating almost maximum 'C'.  (The only configuration with higher 'C' would be foil ICs where the '+' & '-' foils are separated only by, say, 1 layer of plumber's teflon tape.)

You need to space the wires apart to reduce 'C'.  (BTW, this naturally increases 'L' but this is irrelevant in an IC, due to the extremely low current flowing.)

Regards,

Andy

[Jens]

With respect, Jens, if you are twisting 'hot' & 'ground' wires of your IC together, you are generating almost maximum 'C'.  (The only configuration with higher 'C' would be foil ICs where the '+' & '-' foils are separated only by, say, 1 layer of plumber's teflon tape.)

You need to space the wires apart to reduce 'C'.  (BTW, this naturally increases 'L' but this is irrelevant in an IC, due to the extremely low current flowing.)

Regards,

Andy

Really?

I've always been told that twisting reduces capacitance, but increases inductance ...

However, it may turn out not to be a problem, since the long interconnect run will be between my GK-1R preamp and the x-overs, as this is what the x-over manufacturer recommends. I know of a few people that use these x-overs with long interconnects with no problems at all, i.e. no loss of high frequency (which could be the danger if capacitance goes too high). They all use interconnects that are either twisted or just standard parallel runs (supposedly worse than twisted).

I'll try it out - haven't had any problems with long interconnects in the past. I even used to have a 10 metre shielded, standard, parallel-run interconnect from my hifi video recorder to my stereo system. This worked beautifully

Cheers,

Jens

[andyr]

Really?

I've always been told that twisting reduces capacitance, but increases inductance ...

However, it may turn out not to be a problem, since the long interconnect run will be between my GK-1R preamp and the x-overs, as this is what the x-over manufacturer recommends. I know of a few people that use these x-overs with long interconnects with no problems at all, i.e. no loss of high frequency (which could be the danger if capacitance goes too high). They all use interconnects that are either twisted or just standard parallel runs (supposedly worse than twisted).

I'll try it out - haven't had any problems with long interconnects in the past. I even used to have a 10 metre shielded, standard, parallel-run interconnect from my hifi video recorder to my stereo system. This worked beautifully

Cheers,

Jens

I have a similar situation to you, Jens, in that I have 11m ICs between my GK-1 and the active XOs.

I have no sonic problems (ie. HF roll-off) because:

a) I use low-C cable (although, yes, the fact that the ICs are 11m long makes them have a higher 'C' than many other people have), and

b) My Zin/Zout ratio is very high.  Zout of the GK-1 is 120ohms, I believe; Zin of the active XOs is 100K.  Hence my ratio is >800 ... and this high a ratio can cope with the relatively high total 'C' with no problems. 

And re. twisting and 'C' and 'L':
* high 'C' and low 'L' results from having the two conductors very close together.  (Foil cables are the best example of this.)
* low 'C' and high 'L' result from spacing the two conductors apart.  (Naim NAC-5 is a good example of this, for speaker cable.)

Regards,

Andy

[Jens]

I have a similar situation to you, Jens, in that I have 11m ICs between my GK-1 and the active XOs.

I have no sonic problems (ie. HF roll-off) because:

a) I use low-C cable (although, yes, the fact that the ICs are 11m long makes them have a higher 'C' than many other people have), and

b) My Zin/Zout ratio is very high.  Zout of the GK-1 is 120ohms, I believe; Zin of the active XOs is 100K.  Hence my ratio is >800 ... and this high a ratio can cope with the relatively high total 'C' with no problems. 

And re. twisting and 'C' and 'L':
* high 'C' and low 'L' results from having the two conductors very close together.  (Foil cables are the best example of this.)
* low 'C' and high 'L' result from spacing the two conductors apart.  (Naim NAC-5 is a good example of this, for speaker cable.)

Regards,

Andy

Well, my interconnects will only be approx. 3 metres long each, perhaps even only 2.5 metres. X-over input impedance is around 10 k, which according to the manufacturer is more than enough to counter any slight increase in capacitance due to the extra length compared to a standard length (e.g. 1 metre) interconnect.

Also, I will have measuring equipment available, so any roll-of will quickly be revealed.

It is not a worry!

Cheers,

Jens

[Jens]

Just got word from Hugh yesterday that my modules are on their way to Denmark
I am very much looking forward to putting these little darlings to work in my system

Even though they are "only" going to power the bottom end of my system, it should be borne in mind that with an x-over frequency of 250 Hz, they will have a profound effect on both lower midrange as well as the actual bass range.

More later

Cheers,

Jens

[AKSA]

Jens,

Let us hope the transit is swift and secure, and that they arrive without damage.  It's a long way from Oz to Denmark!!   

I received word yesterday from Miro in Ljubliana that his NAKSA 100s made it through safely just yesterday!  I'm very happy;  he is hooking them up this weekend, so very soon we shall have his assessment!

These really are stunning performers, with a level of bass output, midrange liquidity and top end clarity that is a revelation.  It's Saturday night and I've just started on the next ten modules, with more orders swiftly coming on.....   

 
Cheers,

Hugh

[guest1632]

Jens,

Let us hope the transit is swift and secure, and that they arrive without damage.  It's a long way from Oz to Denmark!!   

I received word yesterday from Miro in Ljubliana that his NAKSA 100s made it through safely just yesterday!  I'm very happy;  he is hooking them up this weekend, so very soon we shall have his assessment!

These really are stunning performers, with a level of bass output, midrange liquidity and top end clarity that is a revelation.  It's Saturday night and I've just started on the next ten modules, with more orders swiftly coming on.....   

 
Cheers,

Hugh

Hi Hugh,

A question about wiring. I know you don't really put much in to that, but I was wondering what you would use for both the input and speaker/output wiring? Also, how long a length between the board and case terminals for both in and outs would I need? Thank you.

Ray Bronk

[AKSA]

Hi Ray,

I use color coded multistrand high current wire I source locally, six nines copper, rated to 25A continuous.  I have not noticed differences with the short runs used inside amps with the one exception of milspec aeronautical wire (Whitmore and Tygadure) which is silver coated copper, with teflon insulation.  That seems to sound quite tizzy.

YMMV, of course, but wire and cable choices become more significant with longer distances - like speaker cables.

Cheers,

Hugh

[guest1632]

Hi Ray,

I use color coded multistrand high current wire I source locally, six nines copper, rated to 25A continuous.  I have not noticed differences with the short runs used inside amps with the one exception of milspec aeronautical wire (Whitmore and Tygadure) which is silver coated copper, with teflon insulation.  That seems to sound quite tizzy.

YMMV, of course, but wire and cable choices become more significant with longer distances - like speaker cables.

Cheers,

Hugh

Hi Hugh,

ok, so how much for input and output wiring approximate in inches respectively are you using, say 6 inches for input and same for outputs. This is assuming case config with amps on either side of case with Trafo in center.

Ray

[AKSA]

Hi Ray,

I use about 6" of coax for inputs, and around 8" for outputs, left and right channels.  Power supply leads are around the same length.

Not a lot, in truth, most important qualities are EMI resistance for signal wire, and low DCR for all other leads.  The output inductor and 10R resistor are inserted into the hot output wire.

Cheers,

Hugh

[guest1632]

Hi Ray,

I use about 6" of coax for inputs, and around 8" for outputs, left and right channels.  Power supply leads are around the same length.

Not a lot, in truth, most important qualities are EMI resistance for signal wire, and low DCR for all other leads.  The output inductor and 10R resistor are inserted into the hot output wire.

Cheers,

Hugh

Hi Hugh,

That output inductor, is that to stop possible oscillations at high freqs? i had an amp once that had an inductor in series with one of the leads of the outputs going to the speakers. He told me this was just a safety precaution, to prevent the amp from going in to oscillations at high frequencies if it was overdriven. Well, I then bypassed the choke, and the amp sounded even better without it.

Ray Bronk

[AKSA]

The inductor is a useful tool.  It prevents EMI entering the amplifier from the oft unshielded speaker cables;  they act as an aerial.  Secondly, at very high frequencies, supersonic, should there be any transient instability in the amp, the inductor prevents the amp 'seeing' the highly reactive load of the speaker, with its voice coil inductance and high capacitance values in the crossover.  This tends to stomp on oscillations before they do any damage.

Any feedback amp should carry an inductor on its output, typically 1uF to abour 7uH, depending on the design.  I use 1.4uH.  The jury is out whether you can 'hear' any bad effects from this inductor, but I find that designing for worst case is only prudent.

Cheers,

Hugh

[Jens]

The inductor is a useful tool.  It prevents EMI entering the amplifier from the oft unshielded speaker cables;  they act as an aerial.  Secondly, at very high frequencies, supersonic, should there be any transient instability in the amp, the inductor prevents the amp 'seeing' the highly reactive load of the speaker, with its voice coil inductance and high capacitance values in the crossover.  This tends to stomp on oscillations before they do any damage.

Any feedback amp should carry an inductor on its output, typically 1uF to abour 7uH, depending on the design.  I use 1.4uH.  The jury is out whether you can 'hear' any bad effects from this inductor, but I find that designing for worst case is only prudent.

Cheers,

Hugh

Hi Hugh,

For an application with virtually no speaker cables (only approx. 20 cms) and no x-over (i.e. no capacitance) between amp and driver - do you think it would be safe to remove the inductor?

Cheers,

Jens

[andyr]

Hi Hugh,

For an application with virtually no speaker cables (only approx. 20 cms) and no x-over (i.e. no capacitance) between amp and driver - do you think it would be safe to remove the inductor?

Cheers,

Jens

I would be interested in this, too, Hugh - given I have an identical situation (directly coupled amps with 20cm spkr cables).

If you remember, we put in parallel caps across the output BPs of each monoblock to "get rid of" the RFI which we heard in the Maggie drivers - so mebbe the output inductor is no longer needed? 

Regards,

Andy

[AKSA]

Andy, Jens,

In the case of Maggies, absolutely, IF there is a 3.3nF cap across the speaker terminals to short out any RF which might be picked up and otherwise radiated into the amp.

For conventional drivers, yes, you could try it with and without, but the NAKSA inductors are just 1.5uH, not big, and I rather doubt you'd hear a difference, but it's surely worth a try.

The NAKSA has reduced global feedback, just 31dB, and a VERY low impedance feedback network, making it very difficult for EMI to get into the amplifier.  These features make it possible to delete the output inductor, BUT, you need to verify first if there is an audible difference with it and without it.

As you note, my conservatism and extreme caution is showing.  After 15 years in this game, I've seen some might interesting things happen, so I'm very aware that problems lurk at every turn!!

Hugh

[Jens]

Andy, Jens,

In the case of Maggies, absolutely, IF there is a 3.3nF cap across the speaker terminals to short out any RF which might be picked up and otherwise radiated into the amp.

For conventional drivers, yes, you could try it with and without, but the NAKSA inductors are just 1.5uH, not big, and I rather doubt you'd hear a difference, but it's surely worth a try.

The NAKSA has reduced global feedback, just 31dB, and a VERY low impedance feedback network, making it very difficult for EMI to get into the amplifier.  These features make it possible to delete the output inductor, BUT, you need to verify first if there is an audible difference with it and without it.

As you note, my conservatism and extreme caution is showing.  After 15 years in this game, I've seen some might interesting things happen, so I'm very aware that problems lurk at every turn!!

Hugh

Hi Hugh,

Thank you for this input. I will try it once I have the NAKSA modules mounted on the rear of the speakers, which should make it very easy to bypass the inductor. Theoretically, I believe an inductor affects dampening factor, but I'm not sure how much. Anyway, an inductor is a passive component I would prefer to be without in an all-out active setup 

Andy, if you get to try it out before me, kindly post results here 

Cheers,

Jens

[guest1632]

Hi Hugh,

Thank you for this input. I will try it once I have the NAKSA modules mounted on the rear of the speakers, which should make it very easy to bypass the inductor. Theoretically, I believe an inductor affects dampening factor, but I'm not sure how much. Anyway, an inductor is a passive component I would prefer to be without in an all-out active setup 

Andy, if you get to try it out before me, kindly post results here 

Cheers,

Jens

Hi Hugh and Jens,

From what I remember on this one amp I had, it had an inductor in series with one of the speaker leads. There was a difference without it, but suttle at best. If anything the only difference I remember is without the inductor there was a slight volume increase. That was mainly it. Let's put it this way, if the unit in question sounds pretty darn good with it in, just tacking a wire across the inductor will tell you if there is a difference or not. And you can do this in real time, while it is playing tunes. The amplifier I had was manufactured out of Canada. Don't remember the brand. This was in the early .80's. Since then, amplifier designs and parts have improved immensely.
Ray