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Re: P50 Stepped attenuators
Posted: Mon Jun 17, 2019 7:06 pm
by _D_S_J_R_
Thing is, look what's in the gear upstream and downstream of this sodding attenuator! Also the distortion the source and amp puts in, let alone the speakers and whatever they're doing. A couple of sodding resistors ain't going to transform or ruin anything I'm sure - and if metal films took fillings out compared to carbon types, I'm certain something else was going on as well as this. Maybe the metal films allowed ringing the carbons didn't - no idea. In this case, the amp will almost certainly dominate what's going on and anyway, the first thing the +ve signal sees when it gets to the circuit board is a couple of 1/4W metal film resistors!
Re: P50 Stepped attenuators
Posted: Mon Jun 17, 2019 7:11 pm
by Hannes-Gregor
1/2W!
Re: P50 Stepped attenuators
Posted: Mon Jun 17, 2019 7:32 pm
by Ali Tait
_D_S_J_R_ wrote: ↑Mon Jun 17, 2019 7:06 pm
Thing is, look what's in the gear upstream and downstream of this sodding attenuator! Also the distortion the source and amp puts in, let alone the speakers and whatever they're doing. A couple of sodding resistors ain't going to transform or ruin anything I'm sure - and if metal films took fillings out compared to carbon types, I'm certain something else was going on as well as this. Maybe the metal films allowed ringing the carbons didn't - no idea. In this case, the amp will almost certainly dominate what's going on and anyway, the first thing the +ve signal sees when it gets to the circuit board is a couple of 1/4W metal film resistors!
System remained the same other than changing the resistors Dave, so how do you then explain the difference in sound?
Try shunting any of the pots you have with various resistors. If you haven’t tried it before, you will be very surprised how much difference there is between resistors.
Re: P50 Stepped attenuators
Posted: Mon Jun 17, 2019 8:13 pm
by valvesRus
Ali Tait wrote: ↑Mon Jun 17, 2019 7:32 pm
Try shunting any of the pots you have with various resistors. If you haven’t tried it before, you will be very surprised how much difference there is between resistors.
Shunting a "normal" potentiometer with quality resistors (2) can be seriously beneficial.
http://www.world-designs.co.uk/forum/sh ... php?t=5795
http://www.world-designs.co.uk/forum/sh ... php?t=6885
Re: P50 Stepped attenuators
Posted: Mon Jun 17, 2019 10:09 pm
by Vinyl-ant
I've used the charcrofts (9 quid apiece iirc) as the shunt on a khozmo stepper and they were very smooth compared to the amrg amtrans that they usually come with. Ime they were worth it. Be aware you will lose some gain as you have added a permenant series resistance in line with the input and put the pot in the earth side of the potential divider you have formed
Re: P50 Stepped attenuators
Posted: Mon Jun 17, 2019 10:12 pm
by Ali Tait
Re: P50 Stepped attenuators
Posted: Tue Jun 18, 2019 9:55 am
by 29mile
Apologies for hijacking this thread but does anyone know if it is possible to fit a stepped attenuator into a AP80 ?
I know Richard always said room was extremely tight in the AP80 so suspect it may be diffcult to do.
Re: P50 Stepped attenuators
Posted: Tue Jun 18, 2019 10:00 am
by Daniel Quinn
That would entirely be dependant on who you got to fit it, their level of skill and level of bullshit.
Re: P50 Stepped attenuators
Posted: Tue Jun 18, 2019 10:00 am
by Ed345
I've got an AP80 with a stepped attenuator, so it is possible. It is a very full box though it may or may not fit depending on the specific switch and the exact layout of the power supply.
Re: P50 Stepped attenuators
Posted: Tue Jun 18, 2019 1:49 pm
by _D_S_J_R_
I'd recommend leaving well alone just for now. The 70 and probably the 80 have large finned plate heat-sinks inside taking up some height and it would be a royal pain to try to un-stick them and move them back, assuming there'd be any space. The stock cheap pot isn't as bad sonically as it looks visually - honestly it isn't.