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Linn 2250

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2 hours ago, Briain said:

...and I also have enough scrapped 2250 parts (one spare case, one busted PSU, two working PSUs and several audio expired boards; two of them quite dramatically so - one has vaporised PCB tracks...

Seems it was an common occurrence on 2250s, I have one with that same problem.

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15 hours ago, vicdiaz said:

Seems it was an common occurrence on 2250s, I have one with that same problem.

Hi Vic.

My understanding is that the very badly damaged one's woes resulted from an unfortunate incident whereby it was playing when one of the speaker connections was shorted out. Fortunately, I got the last ever 2250 board from Linn Products and as soon as I'd fitted and tested it - with one of the spare SMPSs that I had - I ordered a Dynamik, so in terms of its internal electronics, I definitely now have the 'youngest' of all the 2250's ever made. :) Personally, I think it's highly commendable that even the original SMPS can deliver enough current (and the output stage then deliver it to the load) that it can actually melt the thick copper tracks feeding DC to the output devices; that totally demonstrates beyond any doubt that it is a proper amplifier, in my book ('tis in fact one reason why I like them so much)! :D

Interestingly, this one also had ruptured electrolytic capacitor cases in the power supply, so it looks like when the short was removed (i.e. the track vaporised) the act of removing the huge load perhaps resulted in the PSU Voltage soaring. Anyhow, I do have two spare SMPSs and I reckon there might be enough working bits to fix the other faulty board (which had been involved in a lightning related incident and has lost all the op amps, as well as the balanced/unbalanced switching diodes and what look to be input protection diodes, too). Of course, both boards are really only fit for the recycling skip, but it would be rather fun to create a working amplifier from all these bits, so I do plan to give it a shot. 

Bri

Edited by Briain
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On 08/01/2019 at 21:42, Briain said:

Worth noting that with active Ninkas, Linn extended the bass response (I'm sure a www search will find the handbook showing the difference between active and passive roll off) and when I activated my own Ninka speakers, that was very noticeable (in an extremely good way). When using a DS or DSM to feed a passive system, the original version of Sound Optimisation enables you to mimic the extended roll off of the active variants via adding a small bass shelf in Kondig. I did this for my 212's (same story about passive vs active versions) and in my case, I first asked Phil Budd and he suggested that I start from something like a 50 Hz shelf to mimic the trickery done in the active cards (I cannot recall the level he suggested; I think it might have been as much as +2 dB, but I ended up with it set to +1 dB) and it made quite a significant difference to my passive 212s. You'd have to experiment to find the ideal bass shelf frequency and level to extend the Ninka's roll off, but I would suggest it being well worth doing. You could perhaps try starting with something like 40 Hz at +1 db (I don't know the figures for Ninka; I just plucked these numbers out of the air as a place to perhaps start from) then move that frequency setting up and down until you find out where it sounds best.

Could you please expand on this a bit, or Paul could you chime in? I've recently gone passive from bi-aktiv. I also added a PS Audio Dectet power bar, redid my wiring grounding everything correctly, and adding a Porter Port receptacle. These power tweaks have really improved all aspects of the system, almost making up for the lack of aktiv, but the low end of my Ninkas isn't as deep I feel. Paul, you had me add a custom filter one as shown in the attached photos. I'd love some advice on attempting this bass reclamation hack!

15472701143031008901690434930053.jpg

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Hi Jail4CEO’s,

I don’t see the custom filter 1 at 27.63 Hz applied,  in the photo, but I could suggest to add gain to custom filter 1, incrementally from -11.5 dB towards -9.0 dB to see if that adds more bass for you.

If that doesn’t give you the bass you are looking for, I would also suggest you incrementally add gain to your calculated room modes 1 and 2. For example, -23.0 to -21.0

.

Alternately, Briain’s advice of adding a bass shelf of +1.0 dB  at around 40 Hz or 50 Hz. If +1.0 dB is not enough, add more gain to +1.25, or 1.5 dB

Please let me know if that is helpful?

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