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(one more) ALEPH P 1.7 clone

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Further P1.7 Adventures

Seems like I was being justly harsh on the MKT1813's... I swapped the MKT's out for some panasonic FC's in same values as the BG's - 10uf & 56uf and bypassed with MKP-1830's. The result - who hid the bass????? :bawling:

In all an interesting experiment but one I won't pursue further - the sound in the mids was fine but a bit lacking. Compared to the mkt's the sound was un-involving and lifeless. The kicker was that I still had that scratchy sound. Obviously not a cap problem, and the microphonic behavior was generated by something else. I double checked the PSU board and notice that the solder joins on the IRF610 looked like they were almost touching. Redid the solder joins with particular attention to clearance - those pads seem very very close. Problem _really_ solved this time!! 🙄

Swapped the MKT1813's back in - still no "scratchy" sounds, similar hiss levels to the other channel and no different to with the FC's installed so obviously not cap related unless due to the MKP bypass caps. The MKT1813's are a comparative joy to listen to. I'm interested to see how the BG N's compare.

cheers
Paul
 
Neglected to ok my order from parts connexion so the BG's have been delayed by a few more days :[

anyway here a couple of pics from the trouble shooting phase... I'd swapped out the MKP1813's for some HFQ electrolytics.
 

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There are _choices_ that can be made, just use good quality components in the correct values:

Roderstein MKP1837 are probably an equal or better cap the Wima MKP's from what I've seen/read. For the 680pf Silvered Mica is a highly regarded option, the Wima's wim mentions will also work well, and I'm using some cheapish radial polystyrene caps at present. I am considering changing to LCR extended foil polystyrene, but I'm going to wait til after my BG's arrive so I have better idea of what changes the components bring.

I use RSComponents or Farnell, and a local surplus supplier...

btw TIA = thanks in anticipation

cheers
Paul
 
Mikkel @ dantimax has finally got all the parts in for my order, and my BG N's are winging their way from Canada so in the next couple of weeks I'll really be able to see how the P1.7 performs 🙂

all I have to do now is find a suitably classy shoe box to house the whole thing.
 
Hi Teake,

I'm not sure how well those results translate. The tests were done as x-over caps.

In the P1.7 the in/output caps – for example – have a DC bias voltages of around 13V and 26V respectively. This apparently has a definite effect on the performance of the caps, so you'd need to take the findings with a pinch of salt.

For a comparison of output coupling caps you might like to check out:

http://www.ecp.cc/cap-notes.html

again this doesn't replicate the conditions of the P1.7 but is probably closer to our application.

cheers
Paul
 
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