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Thanks Satie, I'm getting there! - (slowly!)

Posted by Davy (A) on August 15, 2010 at 17:43:28

In Reply to: RE: DIGITAL only posted by Satie on August 15, 2010 at 16:30:17:

Thanks Satie,
Thanks a lot for your great advice once again.
I have got the point now about the external crossover boxes, - it really is a waste of money buying them and the only advantage of having them is if I ever want to resell the speakers. So I will definitely try active or PLLXO options first, as I don't intend the sell the 3.3Rs anytime soon! (though mind I've not heard them in my room yet, they might terrible!, - lets hope not!)

Ahh I see you if you want to use two PLLXOs you get too much insertion loss, particularly from the 3rd order one for the bass, unless you build one with inductors which I obviously can't do easily.

So are you saying I could build a 3rd order PLLXO without inductors and use it for the bass if I use another active preamp?. I have another 2 available apart from the 2 Quad preamps (I will sell the Quad 66 but have have two NAD active preamp which sound fine (both with 2v output I think and capable of 12V peak). So where would I put the extra preamp? Between the main premamp and the 3rd order PLLXO or between the 3rd order PLLXO and the bass power amp? Sorry if this seems like a stupid question!

I bought the other NAD 1000 1990s preamp recently (not got it yet) as a spare preamp. Its similar to my NAD 1155, but a little newer. I was trying the 1155 today against the Quad 66 and 99 preamps. It does sound comparable, - more attacking than the 66 and a but less clinical than the 99. So its not bad at all. Its perhaps not QUITE as good as either of the Quads but surprisingly close, and it got a lot more gain too.

I like the Quad 99 preamp as it has it has remote volume, the tilt (which does work OK I've found out), and the adjustable phono stage (which I tried to day and it pretty good as well and very convenient). And of course it has adjustable input sensitivity on all inputs. The 66 sounds good too and a bit more musical but a bit too laid back so I'll resell that and keep the 99 for its more attacking sound and better features.
I'm guessing the NAD 1000 preamp will sound pretty similar to the 1155. Will find out when it comes.
So yeah I'd like to use the Quad 99 as the main preamp if possible. But like you say it has low output, so I if necessary I could use one of the NADs instead as the main preamp if that would be better for PLLXOs. The NAD 1155 has two sort of preamp outputs, - one is normal level and one is "high" level, - looking at the specs. The high one does have more gain than the normal one. And according to the specs the high level output can output a max peak voltage of of 15V in 10K (normal output gives 12V max into 20K). The output impedance of them is 600 ohms for the normal output and 220 for the high. So I think either of these outputs on this NAD 1155 preamp is more beefy than either of the Quad preamps. The NAD 1000 preamp only has the normal level output but according the specs again it can also output 12V into 20K max output, (and its output impedance is 220ohms).

So yeah do you think it would be possible to use one of these higher output NAD preamps feedling 2 PLLXOs, or would I still need another active preamp for the bass side? Like I say I could use the Quad 99 (or a NAD) and one of the NADs on the bass side if needed.

I hear what you say about the Behringer, the problem is right now I missed those used ones on Ebay (and none more have turned up) and I can't afford to buy a new one right now until I sell the Quad 66! (its summer and selling is slow!), and I need to pay for the 3.3Rs this week too (got them for £700 without the crossover boxes).
So I was thinking of maybe trying the 2 PLLXOs just to get started, then get the Behringer which I have the funds. I recognise the Behringer is great to have because the flexiblilibty it has in optimising the bass, and the sound potential if you get the output stage upgraded.

I've been reading aroudn about PLLXOs and foudn diagrams of 1st and 2nd order one but now 3rd order ones. I read though that a 3rd order low pass PLLXO is just three caps and three resistors? Is that right? And if so have you any ideas how I calculate the values? (haven't a clue!) If this is a really bad idea then let me know (and I'll wait and get a DCX2496 instead) but like I say I have 3 active SS preamps (Quad 99, Nad 1155 and NAD 1000) I could use for this 2 PLLXO set up if it might work.

Thanks again for your patience and help!
Cheers,
Colin

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