x-over for Kef iQ30 - Page 4

RAART · 10:44 PM

If anyone wonders about my system components and while I am striving to mod iQ30, here they are:

Premap/Headphone amp: Antique Sound Lab MG OTL 32 DT
Amp: Rotel RB-1050
Tuner: Parasound TDQ-150
CD/DVD (temporary solution): Cambridge Audio DVD99 planing to get some good CD player
Speakers: PSB G-Design GB1 and KEF iQ30 and outstanding project with Jordan JX92S original drivers not the new one (it is on hold for now - no time to build cabinets)
Headphones: Sony MDR-7506; Beyerdynamic DT-931 (from 90's not the new ones);
TT: Sony PS-X9 (unfortunately broken but Sony is willing to repair it just need to ship TT to Sony BC - Vancouver)
Other: NAD AV 713; Denon AVR-588; Onkyo TX-8511; Luxman L-3; and some Sony and Yamaha DVD's;

I have my old stuff in Europe (in my house) but didn't get them here... T+A speakers, T+A Pre/End Amp combo; Marantz CD16 and Rotel CD players, Canton GLE70 speakers (from late 80's) and some Cardas and Kimber cables.

tuantran · 29th May 2012, 10:30 PM

I agree with the article: " All the bypasses sound bad ".

RAART · 30th May 2012, 03:38 AM

Quote:

Originally Posted by tuantran

I agree with the article: " All the bypasses sound bad ".

One more reason to leave bypass as an option for now... I might experiment later on.

system7 · 30th May 2012, 09:13 AM

I was just reading the KEF iQ30 6moons review, RAART:

6moons audio reviews: KEF iQ30

Those cabinets look very well made and reinforced. I can't see how you'd better them really. The damping is a bit CHEAPISH with a roll of BAF wadding. Being a reflex, you probably want as little in the way as possible. It could be worth fixing some bitumen or car-door damping sheets to the sides and losing the wadding. I found a piece of rubber backed carpet tile on the back panel just like the put on office floors worked well with reflex. Secured with double-sided tape. The idea is to absorb the midrange a bit before it comes out of the reflex port. You don't want to overdo the absorbtion with reflex or you take away its liveliness.

These are a million miles away from a Tannoy dual-concentric, with paper bass laminated with titanium and metal dome tweeter. The tweeter is evidently not very efficient, so you don't have a lot of scope to modify the crossover. It looks like these low impedance speakers will always be standmounters rather than wall-mounted bookshelves to me. I'm a bit surprised how simple the crossover is, in fact. I'd have thought that bass unit would need more rolloff to avoid breakup.

Better capacitors are going to help, IMO. And a Zobel on the tweeter worth trying.

RAART · 30th May 2012, 12:11 PM

I forgot to mention but I did already was looking into this SOUND COAT as well as this Deflex sheet.

In regards of tweeter I do not know but I got this info "would you prefer I give you the values to the XQ20 instead? Steep 24db slope xover on the mid/tweeter vs. the 12db slopes on your iQ30, both which use the same driver in case you didn't know" and now I am a bit hesitating what to do...
Still waiting for those information from the same source. I am just wondering if anyone can verify if the XQ20 and iQ30 drivers are the same?

5th element · 30th May 2012, 04:34 PM

Quote:

Originally Posted by system7

Mixing hardwood with chipboard or MDF or plywood is very bad and creates resonance.

As far as I am concerned I'd expect the opposite to be true. Using dissimilar materials, providing they are intrinsically well damped would only act to stop resonances from occurring, especially if they are laminated.

Quote:

Originally Posted by system7

I was just reading the KEF iQ30 6moons review, RAART:

It could be worth fixing some bitumen or car-door damping sheets to the sides and losing the wadding.

These are not the same thing though are they? Bitumen sheets or damping pads affixed to the sides of the cabinet are there to prevent or help stop the enclosure from resonating.

Wadding on the other hand is there to absorb and scatter energy inside the cabinet and to help dissipate internal standing waves.

One one hand you do want to keep a ported enclosure relatively free from wadding, but at the same time you need enough to prevent issues from occurring. I believe Zaph has measurements showing this on his website.

RAART · 30th May 2012, 05:32 PM

I just was reading this:

"The iQ series cabinets are only 1/2" thick mdf laminate covered with minimal bracing. For the DIY'er you can reduce cabinet resonations in the iQ series by fiberglass coating the inside with fiberglass matte and bondo. I did it with my iQ series to get rid of the cabinet resonations, which does seem to make a mild improvement."

I think something is there...

Tomom · 30th May 2012, 09:48 PM

5th element doesn't talk much, but when he does he is spot on...

tuantran · 31st May 2012, 03:45 AM

I know Nuance, a Canadian speaker company, using only damping pads to cover all the wooden surfaces inside the enclosure of Nuance speakers. I believe that there is a good reason for Nuance using only damping pads for its speaskers. My Nuance bookshelf speakers (ported) sound very good and I like the sound of speakers with only damping pads.

tuantran · 31st May 2012, 06:19 AM

When I modify a crossover of a speaker, I try to replace components with the same brand and type for capacitors or resistors unless the costs of some greater value capacitors are too high. I did many tests on many different brands of speakers and I like the sound of speakers with the same brand and type for capacitors or resistors in crossover networks. I like to replace resistors with higher wattage ones because I can hear the differences.Specially the resistor of the impedance equalization for woofer. Bass is cleaner (less distortion) with higher power resistor. I do not hear any difference if I replace resistors with the same wattage, higher quality ones.

29th May 2012, 10:19 PM	#31
RAART diyAudio Member Join Date: Jan 2012 Location: Toronto, ON	If anyone wonders about my system components and while I am striving to mod iQ30, here they are: Premap/Headphone amp: Antique Sound Lab MG OTL 32 DT Amp: Rotel RB-1050 Tuner: Parasound TDQ-150 CD/DVD (temporary solution): Cambridge Audio DVD99 planing to get some good CD player Speakers: PSB G-Design GB1 and KEF iQ30 and outstanding project with Jordan JX92S original drivers not the new one (it is on hold for now - no time to build cabinets) Headphones: Sony MDR-7506; Beyerdynamic DT-931 (from 90's not the new ones); TT: Sony PS-X9 (unfortunately broken but Sony is willing to repair it just need to ship TT to Sony BC - Vancouver) Other: NAD AV 713; Denon AVR-588; Onkyo TX-8511; Luxman L-3; and some Sony and Yamaha DVD's; I have my old stuff in Europe (in my house) but didn't get them here... T+A speakers, T+A Pre/End Amp combo; Marantz CD16 and Rotel CD players, Canton GLE70 speakers (from late 80's) and some Cardas and Kimber cables. Last edited by RAART; 29th May 2012 at 10:44 PM.

30th May 2012, 09:13 AM	#34
system7 diyAudio Member Join Date: Aug 2008	I was just reading the KEF iQ30 6moons review, RAART: 6moons audio reviews: KEF iQ30 Those cabinets look very well made and reinforced. I can't see how you'd better them really. The damping is a bit CHEAPISH with a roll of BAF wadding. Being a reflex, you probably want as little in the way as possible. It could be worth fixing some bitumen or car-door damping sheets to the sides and losing the wadding. I found a piece of rubber backed carpet tile on the back panel just like the put on office floors worked well with reflex. Secured with double-sided tape. The idea is to absorb the midrange a bit before it comes out of the reflex port. You don't want to overdo the absorbtion with reflex or you take away its liveliness. These are a million miles away from a Tannoy dual-concentric, with paper bass laminated with titanium and metal dome tweeter. The tweeter is evidently not very efficient, so you don't have a lot of scope to modify the crossover. It looks like these low impedance speakers will always be standmounters rather than wall-mounted bookshelves to me. I'm a bit surprised how simple the crossover is, in fact. I'd have thought that bass unit would need more rolloff to avoid breakup. Better capacitors are going to help, IMO. And a Zobel on the tweeter worth trying. __________________ Good Night, and Good Luck. Best regards from Steve in Portsmouth, UK.

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29th May 2012, 10:30 PM	#32
tuantran diyAudio Member Join Date: Jun 2011 Location: Ottawa Blog Entries: 1	I agree with the article: " All the bypasses sound bad ".

30th May 2012, 12:11 PM	#35
RAART diyAudio Member Join Date: Jan 2012 Location: Toronto, ON	I forgot to mention but I did already was looking into this SOUND COAT as well as this Deflex sheet. In regards of tweeter I do not know but I got this info "would you prefer I give you the values to the XQ20 instead? Steep 24db slope xover on the mid/tweeter vs. the 12db slopes on your iQ30, both which use the same driver in case you didn't know" and now I am a bit hesitating what to do... Still waiting for those information from the same source. I am just wondering if anyone can verify if the XQ20 and iQ30 drivers are the same?

30th May 2012, 05:32 PM	#37
RAART diyAudio Member Join Date: Jan 2012 Location: Toronto, ON	I just was reading this: "The iQ series cabinets are only 1/2" thick mdf laminate covered with minimal bracing. For the DIY'er you can reduce cabinet resonations in the iQ series by fiberglass coating the inside with fiberglass matte and bondo. I did it with my iQ series to get rid of the cabinet resonations, which does seem to make a mild improvement." I think something is there...

30th May 2012, 09:48 PM	#38
Tomom diyAudio Member Join Date: Dec 2010	5th element doesn't talk much, but when he does he is spot on...

31st May 2012, 03:45 AM	#39
tuantran diyAudio Member Join Date: Jun 2011 Location: Ottawa Blog Entries: 1	I know Nuance, a Canadian speaker company, using only damping pads to cover all the wooden surfaces inside the enclosure of Nuance speakers. I believe that there is a good reason for Nuance using only damping pads for its speaskers. My Nuance bookshelf speakers (ported) sound very good and I like the sound of speakers with only damping pads.

31st May 2012, 06:19 AM	#40
tuantran diyAudio Member Join Date: Jun 2011 Location: Ottawa Blog Entries: 1	When I modify a crossover of a speaker, I try to replace components with the same brand and type for capacitors or resistors unless the costs of some greater value capacitors are too high. I did many tests on many different brands of speakers and I like the sound of speakers with the same brand and type for capacitors or resistors in crossover networks. I like to replace resistors with higher wattage ones because I can hear the differences.Specially the resistor of the impedance equalization for woofer. Bass is cleaner (less distortion) with higher power resistor. I do not hear any difference if I replace resistors with the same wattage, higher quality ones.