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RE: Tweeter difference problem with 3.3Rs and more

Hi Satie,
Hope all is well.

Some turntable news, - I got the Technics SL1600MK2, - for £180 so it was not too cheap. Annoyingly a Sl1700Mk2 appeared on Ebay UK just after wards
for only £85 with including shipping, so I bought that as well. So I'll see how I get on and perhaps resell one of them. Looking forward to trying these out.

As for the 3.3Rs, - well I am going through a bad patch at the moment to tell the truth, - I tried the L-Pads (made up a -8.5dB lead and a -5.5dB lead).
They don't really work very well, - the sound is changed somehow, - I could not put my finger on it connected to the speakers so listened to the power amp hooked to my headphones and swapped the attenuator cables for normal unattenauted cables, - with the attenuator cables in place the sound is heavier and thicker and sort of softer too, - it is not good really. The sound is a lot better with a normal cable.

There is some attenuation of the hiss with the attenuator cables, - not a big amount, but there is a further hiss problem as if you increase the input gain on the Behringer the hiss increases once more and you are really backto where you started. So it seems the Behringer input stage is pretty noisy as well as the output stages. So I think there is maybe not a big advantage in using the L-pad with the Behringer from what I have seen so far, - the hiss does not go away. A solution I guess would be to have it upgraded with less noisy and less high gain stages I suppose.

Anyway so for the time being I left out the attenuator cable and wired the NAD to the Behrginer to do the bass. And used the PLLXO on the Quad (but not with the new caps yet)
I tried the 3rd order butterworth LP on the Behrginer with the phase adjustaments you advised, - normal 90 and 180 degree, and inverted 90 and 180 degress. I am still finding it hard to blend the two sections.
A lot of the time the midrange seems too sucked out, - the sound is too U-shpaed. so yeah I am a bit lost now this as well, - but will try again in more depth tomorrow.

On a more positive not later on tonight I've soldered in the new polypropylene caps into the PLLXO. It got to late to test on the speakers so I again tried with heapdhones, - it sounds very good. In fact it now
sounds vastly better than the Behringer doing the HP (I wired that up too and listened with heapdhones to compare).
I am getting a bit skeptical that these two different things (the PLLXO and Behringer) are going to blend well together, - they just sound so different (one good and one not so good), - I know they will be reproducing different sections but from what I have heard on the speakers so far its very hard to blend it well.
I will confirm more firmly tomorrow when I try the upgraded PLLXO on the speakers.

Its a shame the stock 3rd order crossover is hard to build in a PLLXO because of the need for the inductors,- as I maybe its possible a LP PLLXO would have a better chance of Blending well with a HP PLLXO than the Behrginer does. When you are blending a LP and HP PLLXO like this, - do you have all these phase issues/matching to worry about like when you
use the Behrginer and PLLXO? or it that not a problem?
Might I be able to calculate values for a 3rd order LP PLLXO using only caps and resistors and use that extra preamp you suggested?
I guess one problem with that is the preamp with its own sound characteristics would no doubt be another thing that might impede the blending of the two sections.

I guess I could try to get a proper 3rd order LP PLLXO made using inductors that is based exactly on the stock passive speaker level crossover, and get it built with a level control? Is that a viable option?

I am again really quite tempted just to buy the stock external crososver for these speakers and sell the Behrginer. I am looking to get these speaker resaonbely coherent from bottom to top and the way I am trying to do it now is not working. I guess that despite its disadvantages, using the same power amp powering the whole speaker
though all passive speakr level crossovers would have a better chance of producing a coherent sound, - I could still fine tune a bit for my room using the simple Quad tilt control.

I guess it would be a bit rash to give up now on the active or PLLXO scheme, - I'll try again tomorrow. And I'll also see how I get on fixing down the voice coils with
DAP, - as if I somehow accidentaily ruin these speakers it will have been a big waste of money to have ordered the external crossover boxes in the meantime.

I would say for sure that despite the less extended treble the stock 2.7Qr driven from a single amp in passive mode is vastly more coherent than what I've heard so far from these 3.3Rs (with the problems I've had setting them up). And my Dads original passively driven MGIIIs (drive by the Naim 250) from memory, were also much more coherent as well. I really do prefer both of those by a long way from the from what I've heard so far from these 3.3Rs.
Any ideas on where I can go from here? (if not don't worry I'll probably just get the stock crossover boxes eventually and give up fiddling!)

All the best,
Colin


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