[Jens]

Hi Hugh,

Since I have multi-amped system with different amps driving the various parts of the system, I got the idea that there might be some hints for optimising my LF55s for treble and mid work, respectively.

My LF55s are completely unmodified at this point, so we've got a 'tabula rasa' as a starting point.

So here goes:

• For a LF55 to drive a treble unit (in this case the Scan-Speak Ring Radiator) optimally with lots of airiness at the top end, what optimisations would you suggest?
• For a LF55 to drive a mid unit (down to approx. 200 Hz) optimally, what optimisations would you suggest?

Any suggestions are welcomed 

[AKSA]

Hi Jens,

Thanks for the post!  Pardon my slow reply, been away visiting my Mum in South Australia, just back this evening.

This is a toughie......

Y'know, I would not do anything to the amps proper.  They are just fine as is.  But what I would do is replace the input caps, which are pivotal to sound quality.

A VERY high quality metallised polystyrene of 0.22uF for the treble amp (something like an RTX, an Auricap, or a Mundorf silver/oil at a pinch), and a Nichicon Muse 10uF for the midrange amp.  Nothing more need be done;  all the N+ tricks are used on the LFs anyway and I really can't think of any frequency specific improvements.

I do hope this helps!

Cheers,

Hugh

[Jens]

Hi Jens,

Thanks for the post!  Pardon my slow reply, been away visiting my Mum in South Australia, just back this evening.

This is a toughie......

Y'know, I would not do anything to the amps proper.  They are just fine as is.  But what I would do is replace the input caps, which are pivotal to sound quality.

A VERY high quality metallised polystyrene of 0.22uF for the treble amp (something like an RTX, an Auricap, or a Mundorf silver/oil at a pinch), and a Nichicon Muse 10uF for the midrange amp.  Nothing more need be done;  all the N+ tricks are used on the LFs anyway and I really can't think of any frequency specific improvements.

I do hope this helps!

Cheers,

Hugh

Hi Hugh,

Not slow at all - I only posted this yesterday! Hope your mother is doing well.

Thanks for the input on the input caps

I have a pair of 1 uF teflons I might use for the midrange amp.

I was also considering if something could be done to the power supplies (which are also standard) - such as even better rectifier diodes, bypass caps or ... ?

Obviously, there is no point in upping the amount of storage caps for this kind of work ... but would there be any point in using chokes like in the Soraya?

It goes without saying that the most radical solution to the above issue would be to get two Sorayas, but unfortunately these are somewhat beyond my financial reach at this point.

Any further input is absolutely welcome

[stvnharr]

Hi Hugh,

Not slow at all - I only posted this yesterday! Hope your mother is doing well.

Thanks for the input on the input caps

I have a pair of 1 uF teflons I might use for the midrange amp.

I was also considering if something could be done to the power supplies (which are also standard) - such as even better rectifier diodes, bypass caps or ... ?

Obviously, there is no point in upping the amount of storage caps for this kind of work ... but would there be any point in using chokes like in the Soraya?

It goes without saying that the most radical solution to the above issue would be to get two Sorayas, but unfortunately these are somewhat beyond my financial reach at this point.

Any further input is absolutely welcome

Hi Jens,
Have you read my short write up on the psu I recently put together for my LF55?
Are you using an old Aksa psu for your LF?
The 3 pin Schottky's that I used are quite good.  But to make the most effective use of them is to use a diode bridge on each power rail, rather than a single bridge per channel as on the Aksa psu.
This would require a new board.  Chokes are a great idea, but again, new board.

My new psu has most notably gotten me better bass, but it also has added speed and precision to the mix, that was not there previously.  I credit most of the speed to the Schottkys.  But hard to say if there is much benefit to just swapping them out on an older psu. 

Anyway, just thought I'd add that in.

Steve

[AKSA]

Jens,

Steve is on the money;  you can improve things a little with a new power supply, but you'd need a new pcb, much larger, for eight caps, not four.

I could do one for you, but only a fully built one, as this is pretty much proprietary with the Soraya.

Cheers,

Hugh

[andyr]

Hi Hugh,

Since I have multi-amped system with different amps driving the various parts of the system, I got the idea that there might be some hints for optimising my LF55s for treble and mid work, respectively.

My LF55s are completely unmodified at this point, so we've got a 'tabula rasa' as a starting point.

So here goes:

• For a LF55 to drive a treble unit (in this case the Scan-Speak Ring Radiator) optimally with lots of airiness at the top end, what optimisations would you suggest?
• For a LF55 to drive a mid unit (down to approx. 200 Hz) optimally, what optimisations would you suggest?

Any suggestions are welcomed 

Hi Jens,

Although, I haven't done this yet, I have researched the matter and (after input from Hugh and others  ) intend to put Mundorf Silver/oils or equivalent, of different values on the input of each LF, so:
* 2uF on the bass LF100 modules
* 220nF on the mid LF55 modules, and
* 22nF on the treble LF25 modules.

As I understand it, to minimise phase alterations at the XO region in an active setup, the amp needs to have an F-3dB point which is (at least) a decade below the associated XO.  So, as my mids cross over to the woofers at 330Hz, the cap value on the mid amp needs to deliver an F-3dB of 33Hz ... 20Hz in your case, so maybe 470nF would be more appropriate?  My ribbons pass over to the mids at 2,600Hz, so 22nF is sufficient here.

As well as Hugh's new PS, for an optimum active setup you might also consider changing the tweeter LF55 to an LF25?    You said you want "lots of airiness at the top end" ... Hugh commented many years ago that lowering the rail voltage on a 55 (to turn it into a 25) made it sound "like a SET on steroids" so I would suggest that meets your requirement!    It also enables the amp to easily cope with 3ohm speakers, if that's of any interest.

Regards,

Andy

[Jens]

Hi Jens,
Have you read my short write up on the psu I recently put together for my LF55?
Are you using an old Aksa psu for your LF?
The 3 pin Schottky's that I used are quite good.  But to make the most effective use of them is to use a diode bridge on each power rail, rather than a single bridge per channel as on the Aksa psu.
This would require a new board.  Chokes are a great idea, but again, new board.

My new psu has most notably gotten me better bass, but it also has added speed and precision to the mix, that was not there previously.  I credit most of the speed to the Schottkys.  But hard to say if there is much benefit to just swapping them out on an older psu. 

Anyway, just thought I'd add that in.

Steve

Hi Steve,

I certainly read your write-up. Actually, that was what gave me the idea of improving on the diodes. Obviously, I wouldn't want to add capacitors for treble and mid amplification, but on the other hand there might be something in improving further on capacitor quality (although the Nichicons used are already very good).

[Jens]

Jens,

Steve is on the money;  you can improve things a little with a new power supply, but you'd need a new pcb, much larger, for eight caps, not four.

I could do one for you, but only a fully built one, as this is pretty much proprietary with the Soraya.

Cheers,

Hugh

Thanks, Hugh - I may PM you about this 

[Jens]

Hi Jens,

Although, I haven't done this yet, I have researched the matter and (after input from Hugh and others  ) intend to put Mundorf Silver/oils or equivalent, of different values on the input of each LF, so:
* 2uF on the bass LF100 modules
* 220nF on the mid LF55 modules, and
* 22nF on the treble LF25 modules.

As I understand it, to minimise phase alterations at the XO region in an active setup, the amp needs to have an F-3dB point which is (at least) a decade below the associated XO.  So, as my mids cross over to the woofers at 330Hz, the cap value on the mid amp needs to deliver an F-3dB of 33Hz ... 20Hz in your case, so maybe 470nF would be more appropriate?  My ribbons pass over to the mids at 2,600Hz, so 22nF is sufficient here.

As well as Hugh's new PS, for an optimum active setup you might also consider changing the tweeter LF55 to an LF25?    You said you want "lots of airiness at the top end" ... Hugh commented many years ago that lowering the rail voltage on a 55 (to turn it into a 25) made it sound "like a SET on steroids" so I would suggest that meets your requirement!    It also enables the amp to easily cope with 3ohm speakers, if that's of any interest.

Regards,

Andy

Hi Andy,

Thanks for your input. The LF 25 idea is certainly worth considering for the treble amp 

I'm not currently using active filtering for the treble and mid sections of my system. There is a passive crossover between treble and mid drivers, and the midrange driver merely rolls off acoustically between 200 and 250 Hz, and I have helped it along slightly by introducing an appropriately sized capacitor in the signal cable between preamp and LF55. Actually, I have considered changing the input cap of the mid LF55 to bring about the same rollof ...

[AKSA]

Jens,

Ready when you are with that email!!

Hugh

[Jens]

Jens,

Ready when you are with that email!!

Hugh

Hi Hugh,

Sent you a PM about this last week - did you get it?