thoppa

Hi, Same sound really means 'balance' - some speakers sound v bright, others dull, etc - this is what I mean. To me, this is very subjective - "do I Iike this sound ?" However, things like definition on bass guitar chords, shimmer on cymbals, vocal warmth, attack, decay, damping etc all that stuff is the improvement in performance; fidelity in a word. So the exercise for me is improve fidelity but don't mess it up by changing the balance away from what I personally like. So some steps are small, like input caps and others are big, like pllxo instead of pplxo. There is method to the madness. Components are always stand alone stuff and people match them up to other stand alone stuff to get the right balance. Klipsch + Denon is v popular. Klipsch + Yamaha - ow ! I'm trying to go one step further and integrate the components so they are a 'symbiotic' whole. Hence, remove the redundant input cap, (or rather add it to the LF pass channel) as a bias cap is no longer needed. Actually, having just tried the software, I'm now leaning towards increasing the filter order and using a different bias cap value as a third filter - giving a total of four filters for the HF section. Nuts to the phase issues - I'll just try switching pos and neg on the tweeter around each time. Phases are clearly beyond me. The software is likely to prove invaluable - thanks so much for directing me to it. Nutty Tom

Hi, Anyone have any experience of this ? The nice fellas at Pi speakers say this happens everytime a lone cap is connected before a tweeter. The example they gave was a horn-loaded tweeter with a crossover at 1.6Khz and this had resonant peaks at 2.2khz (0.5dB), 1.1Khz (1dB), and 400Hz (4dB). So it seems the protection cap for bi-amping will cause this too ? Cheers, Tom

Hi, Thank you - I misunderstood your post - I thought the second link was a help file for one of the bits of software on the first link. One of the reasons I am trying to work this phase thing out is the next project bubbling in my brain - a four channel tube or op-amp 'pre/headphone' amp with an active crossover (and maybe time delay circuits ? whoa....too much for me I think) that can drive the pllxo. Hence, if I get the pllxo to give a flat response, and know what the phases are up to, I can tailor the tube pre/headphone amp to match; and narrow the bandwidth through the amps yet further, reduce intermod. dist. etc etc. I am mad right ? I have a feeling you think I should dump the pllxo and just use an active crossover.... I dunno why pllxo's don't seem popular. Apart from an insertion loss, and the problem of accurate components for higher orders, they seem to me to be an elegantly simple, if perhaps basic, way of bi-amping. Any comments ? Anyway, just to let you know I am going to take the plunge and take the input cap off the HF pass channel of the amp - why ? Well in my simple way of thinking it means that each channel will be passing though the same number of filters from the time it leaves the DAC to the time it arrives at the drivers. So I will either get cancellation (and so reverse the connections) or I will discover that I need a new brain. I think I know which one you guys are betting on....:-) Thanks again for thr software links, Tom

Hi, Yeah, I probably do seem daft.[:$] I am working through a step by step change that maintains the overall sound (i.e. no cock-ups) but improves performance. A Taguchi-house-of-quality process that is well-messed up...so if the BG is redundant, remove it. If this doesn't mess up the phases then it can only be an improvement. Hence the question. Anyway, I've got to the limit of my ears so maybe I should quit, as you say, over-thinking things and start some proper testing. I'll give the software a go. Any idea about frequency response testing software ? Thanks, Tom

Hi, Thanks for recommending the software. Is there also a simple one that will give me frequency response plots so I can be a bit more scientific about testing this set up ? I don't want to give you more homework !! [:'(] but if you will take a quick look that'd be cool ! Thanks ! Here is a link to the TA2020 amp circuit http://www.tripath.com/downloads/TA2020.pdf They recommend a 2.2uF input but the builder says 4.7uF extends the bass headroom ( I am tempted to use 10uf and have a huge THUMP at switch on when it isn't muted []) And a link to the pllxo (very simple 2nd order circuit, you probably don't even need to look right...) http://www.t-linespeakers.org/tech/filters/passiveHLxo.html The only other component is the protection/HF pass cap in line with the tweeter (tweeter peaking issues anyone...? Grrrr...) which is 3.3uF M-Cap. BTW, for people following this thread, here is also a link to a good analysis of phase/summing that I gave wrongly above : http://www.pispeakers.com/contents.html Open the 'pi crossover document' listed towards the bottom - very informative and factual. Cheers !

Hi, Thanks - figured it must but I had to be sure...! Here's a very specific phase/summing question which maybe someone can answer (specifically I hope, not theoretical analysis including the moon's phase and witches brews etc :-) Simple, yes, no .... I have a bi-amp system with an amp for each speaker that uses a pllxo. I am thinking about removing the input cap (a BG 4.7uF) on one channel of the amp (HF pass) because the input cap's job can now be done by the last cap in the pllxo (a Sonicap 0.047uF). I can connect the Sonicap into where the BG was - it can be the signal coupling cap blocking DC bias from the TA2020 amp chip and a part of the pllxo. The BG input cap is redundant. I have checked this with the amp builder and he agrees. I think I still need to keep the input cap for the other channel (LF) because the caps in the LF part of the pllxo are parallel to the input and not in series like they are in HF so there is no series cap blocking DC bias; I think.....I shall check... So my question is this; am I going to get a relative phase change between the HF and LF of 45 degrees going into the amp if the LF pass channel has an input cap and the HF pass channnel does not ? Can I remove the LF cap also ? Many thanks, Tom

haha.... but when it's sweet, it's soooo sweeeeeet. It's worth the headache...

Hi, I have a locally-made (Chinese) power conditioner - it uses ICs to smooth the power wave I believe. It removed noises from other equipment in the building but did not 'improve' the sound quality by any great margin. My problem was the abysmal building wiring with, I think , earth loops galore. I also use a surge protector because we get huge electrical storms here and they blew a USB soundcard once, and also, the switches in the building, esp my apartment, seem to create surges esp when they switch flourescent lights on / off. If it ain't broke don't fix it ? I have heard that bad conditioners/filters can actually limit current supply in the very short term and create early clipping but I haven't seen any evidence. Tom

Hi Mas, Thanks for the post - forest and trees I get. My forest is RF52 (which incidentally are fantastic), two independent amps and two pllxo's ( match the original Klipsch ). This set up sounds far superior to the original Klipsch running off my Onkyo receiver. So much better that I was stunned at first. I've also moved my room around to find the best position. I have added identical damping materials to the braces and other areas inside the speakers which were undamped. I have played with crossover frequencies and found the Klipsch frequencies and roll-offs sounds best for the woofer but the tweeter I'm not so sure. It isn't cabinet-dependant. I can switch back to the originals and do side-by-side tests with tones and music to check things as I make 'progress'. I think software is the next step to help me tweak. Wrong ? I have a feeling you think the forest/topology is the problem ? So where am I going wrong ? Cheers BTW - here is an article on the various phase/summing problems and it even has mixed orders. I'm still 'studying' this. http://www.passlabs.com/downloads/articles/phasecrx.pdf

Thanks for the advice. When I was growing up there was a series of books called "Janet and John..." that explained life so kids could understand - sadly even your Reader's Digest version was unfamiliar - I'm still at Janet and John level I think - what is N-order ? N is just any number right ? Is there any software you have used and can recommend ? I'll do the usual searches but it's always nice to get personal recommendations. Dr Who also suggested I get some software to play with time shifts in due course so this clearly the way to go. Thanks again.

Hi, Um, yes , complicated isn't it ? I must admit despite reading your post several times, I get lost when you start talking about multiplying. I'm just thinking about playing with all the filters to get the best phase coherence between the treble from 8khz and below and the bass from 400Hz up. My big problem is I just get overwhelmed by the complex stuff, I hate calculus with a passion, and also I can't find much about using mixed order filters together - i.e a 2nd order bass and a 3rd order tweeter which is what Klipsch engineered for the RF52. Everything seems to be about matching orders so I am well and truly stumped. If I at least knew which end of the tunnel might have light I could hope to head that way.... Cheers, Tom

Hi, If you do the the DIY route please post copious details as I'd be very interested in this ! I read posts about the benefits of XLR and it would be a good step up for me to replace my RCAs with XLRs as I have six meters of RCA cables in total. Where is the tube pre-amp kit you mentioned ? Can you post a link please ? Thanks. Tom

Ouch ! I recognise the second pic from a Nicholas Cage movie, Lord of War, I think.

Hi , Firstly, I want to say this is a great forum - lots of good advice, knowledge and experience and it's really been a great help setting up my RF52. I'm very grateful ! Would anyone be willing to tell me if I have this 'phase coherence thing' right in my head ? I've been looking at the signal path and trying to work out the simplest way to ensure phase coherence. I've looked through other posts but I'm still not sure. If I have understood correctly, whenever a signal gets changed by a cap or a coil it shifts phase 90 degrees - but do caps and coils both shift the phase in the same way ? Or is it high-pass and low-pass that shift in opposite ways ? For me, the output of my DAC's headphone amp feeds a passive line level 2nd order crossover for bi-amping - 2 caps and 2 resistors each for HF and LF - so this should shift both signals 180 and as one is bass and the other treble, this means they would shift in 'opposite directions' (I have no idea what I'm saying really...um) and so question 1, are they then out of phase and cancel at the crossover frequency ? These signals then pass through an input cap on the amp (and resistor (the res is in a negative feedback circuit)) to filter out subsonics (I think it is for subsonics because input res is 20K and input cap is a BG 4.7uF). Another shift ? So question 2, as they are both high pass, there is no relative phase change right ? wrong ? The amp is class-T so there is another 2nd order filter at the amp output (low pass to remove the PWM carrier signal I think). So question 3, these are both low pass so there is no relative phase change.....right ? wrong ? Finally number 4, there is the cap in line with the tweeter so now the treble has shifted 90 degrees (270 degrees in total) but the bass has shifted 180 - so I shouldn't get phase cancellation at the crossover frequency I think....but maybe it occurs an octave either side of the crossover ? I'm just taking a wild shot in the dark on the last one.... Any help or comments are very gratefully received ! Thanks,

For anyone following this thread and hoping to build a 'good' system for $1,500 here is my effort. Comments more than welcome... Musiland MD-10 DAC - PLLXO - Class-T Bi-amp - Klipsch RF52 (no crossover) PLLXO - Matched to low-mid output impedance of Musiland MD-10 DAC headphone output (40 to 80 ohm seems to work best so I've gone for the higher end to minimise distortion) and 20K input impedance of Charlize class-T amps : PLLXO Caps are Sonicap Gen I and resistors are PRP .5W from Sonic Craft (I'm upgrading from the Solens and carbon film resistors I have been using to set things up) Low pass - 82 ohm and 820 ohm series, 2.2uF and 0.22uF parallel. This 12dB per octave at 900Hz. Higher crossover frequencies make the speakers sound shallow and really really horrible. I started to hear awful resonances that has made me interested in better damping for the cabinet side walls and the internal braces. There's plenty of well-defined bass across the range so I don't mind losing a little if I might get a smoother overall response. High pass - 0.47uF and 0.047uF series, 82 ohm and 910 ohm parallel (910 will be increased to alter the roll-off - actually the sound is not how I'd like it yet so I expect I'll increase this but it is a close match to the original Klipsch in theory). Two 12K ohm resistors are used as a potentiometer to replace the power level attenuator. Again, I expect to play with these to vary the overall bass/treble balance (being careful to keep the overall value including the amp's input impedance at 20K !). Power level capacitor will be 3.3uF Mundorf M-Cap Supreme silver/oil when the postman comes....I'm waiting by the box..... I'm still fussing over stuff like phases, optical cable and power supply caps but I need to burn-in everything together before I do more changes. As for time-shifts, well, I need to hear if there really will be an improvement that would far exceed the problems of adding an electronic circuit in the path. I feel, but don't know, that positioning everything well will minimise this and it is overkill. Am I way off again ? Total cost is a shade under US$1,500 including power conditioner, ASIO soundcard, cables etc. Very pleased overall. Cheers, Tom

Hi, Thanks - I've done a search for his posts and will trawl through them. The ideal for me would be a digital crossover that takes an optical feed and a feed from a HD DVD/Blu Ray and has top notch DACs and a sweet headphone amp....and is "affordable"......fat chance eh..... Anyway, my system is sounding quite good and I'm getting a decent-sized stereo sweet spot so now it's not 'urgent'. It might be an idea to wait until the latest format war has settled a little and 24bit/192Khz is common.... Many thanks for your help - you have saved me from several mistakes - I really appreciate it [] Tom

Thanks again for teaching me ! I've been looking at a Behringer digital crossover - are they any good ? It has the various crossover types and orders, attenuation and delays , which I now understand the need for...:-) Cheers, Tom

It might seem a dumb thing to be doing but it is because I don't have test equipment that I'm relying on my ears and my math, so I have tried to change the set up and keep the sound the same or better. One day I shall invest in some test gear - and an active crossover - but at the mo I'm strapped for cash. Anyway, thank you for explaining the time offset. I realise now this will need an active crossover - it isn't to do with phase changes in a passive network. My bad. I have assumed the passive phase changes will pass through the amp but as the signal is converted to pwm in the amp and then back again, is this assumption incorrect ? Is the only phase change due to the cap in line with the tweeter ? As you said before, will I not hear these changes anyway ? Thanks again, Tom

So now I've got the speakers working musically and tonally, I'd love to get them sorted for their 'alignment' as, I guess, this will improve the staging and make the position of the listener less critical. Am I wrong about this too ? Here is a link to the site that helped me calculate the PLLXO. http://www.t-linespeakers.org/tech/filters/passiveHLxo.html It says the values it gives are close to Linkwitz-Riley but I have no idea if they are, or how much different Butterworth would be... Info is what I really need.... Cheers, Tom

You said it was time offset and the crossover.... The delay for each bandpass is based upon the time offset determined by measurement of the impulse response of the system. This time offset is specified in the crossover for each bandpass. This will align the acoustic centers ....so from this I think an impulse test is used to measure the time offset which in turn is used to configure the crossover so that the acoustic centers are aligned. So alignment is, I guess, about using the crossover to align the acoustic centers. That's why I talked about the crossover in my speakers...and why it seems Klipsch have mixed orders and designs in the one crossover. Obviously from your response I have misunderstood. Would you explain ? Here is how I worked out my RF52 crossover.

Hi, Thanks for that....I guess alignment is why the bass used LR and the treble used B'worth and why they are different orders and so far apart in terms of frequency ? The bass was easy - 2nd order LR passive line level is no problem to match to the Klipsch 2nd order LR in the speaker. What I don't know is whether a passive line level filter creates a phase change that continues on through the class-T amp - I assume it does. I just don't know for sure. The tweeter was not so easy mainly due to a lack of information. So I have gone for a 2nd order LR passive line level and then a 1st order B'worth in line with the tweeter. I have probably messed up the alignment so that is why I say it is not easy. I also don't know the exact input impedance of the amp but it is around 20K so I used that in the calculations. Easy ? Not for me. If phasing, alignment and input impedance were not issues then I would not hesitate to say it is as easy as making a fool of myself. If you know how to replicate a 3rd order butterworth passive line level and 2nd order passive line level please let me know as I only have the maths for LR. Cheers, Tom.

Music they will play at the wake for DVD-A....while dual disc is trying to resurrect it..... http://consumers.umusic.com/dvda/releases.html Anybody know a software player for DVD-A ? Cheers, Tom

Here is a link to a list of dual discs with DVD-A content : http://consumers.umusic.com/dvda/releases.html My Snow Patrol has DVD-A - my soundcard supports 96Khz at 24Bit so now it is just a case of finding software to play it ! What do you guys use ? Cheers, Tom

Simple concept, not so simple to do. I found out that my Klipsch RF52 have a 2nd order low pass Linkwitz-Riley for 4 ohms at 900Hz, and a 3rd order Butterworth high pass for 12 ohms at 4kHz. The stated crossover is 1.8Khz. The bi-amp has made a small difference - bass is better defined, treble more crystal. I am pleased with the results now it is done but it was a real headache and I'm not sure I'd recommend it all things considered. I have no speaker cables as the amps connect into the internal speaker wiring (which I might upgrade one day) so I can avoid that debate ! So what is "aligning the acoustic centres" ? Cheers

Hi, Thanks for the info. The sleeve doesn't say anything, just that it is designed for ordinary DVD players so I guess I am getting 48Khz 16 bit, as I think this is standard DVD video output. I tried switching my DVD to LPCM too but there was no output so it isn't DVD-A I think. Cheers ! Tom