Question about Output Cap in LA2a
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NewYorkDave
Well-known member
Yes, polarized caps will pass AC. They just require appropriate bias. The output of the White cathode follower sits several volts positive with regard to ground, and provides the needed bias.
Better sound.
NewYorkDave
Well-known member
Yeah, but maybe a little too barebones. A FILM cap will usually perform better for audio coupling than an electrolytic, but that's an issue of dielectric type, not polarization. It's hard to find film caps in high values at high voltage ratings, which is exactly why you see a 'lytic being used there. If you wanted to be really anal about it, you could replace it with a suitable number of film caps in parallel. But hey, people seem to like the sound of the LA-2A as-is, so that cap can't be causing too much damage :razz:
DrFrankencopter
Well-known member
NYD, I'm sure you can find a Solen cap with a high enough value, at a high enough voltage rating for the LA2A, and they don't cost a fortune too.
I seem to recall the La2A output cap being a 16uFd (going off memory here). Partsconnexion has the Solen 16uFd, 400V rating for $5.40.
When I do my La2A I'll be using this cap (and Jensen or Lundahl transformers), but then again I guess I won't be doing a clone eh?
Cheers,
Kris
I seem to recall the La2A output cap being a 16uFd (going off memory here). Partsconnexion has the Solen 16uFd, 400V rating for $5.40.
When I do my La2A I'll be using this cap (and Jensen or Lundahl transformers), but then again I guess I won't be doing a clone eh?
Cheers,
Kris
NewYorkDave
Well-known member
That's not a bad price. I didn't find them on Partsconnexion's website, but I did find them on some other sites, at about the same price.
Looking around, I see that Parts Express carries a good selection of higher-voltage, higher-value film caps at reasonable prices:
http://www.partsexpress.com/webpage.cfm?webpage_id=3&SO=2&DID=7&CATID=31&ObjectGroup_ID=163
I'm glad you brought that up, because the last time I looked into 400V films with values of several uF, they were quite expensive and not easy to get. Looks like the situation has improved....
Looking around, I see that Parts Express carries a good selection of higher-voltage, higher-value film caps at reasonable prices:
http://www.partsexpress.com/webpage.cfm?webpage_id=3&SO=2&DID=7&CATID=31&ObjectGroup_ID=163
I'm glad you brought that up, because the last time I looked into 400V films with values of several uF, they were quite expensive and not easy to get. Looks like the situation has improved....
NewYorkDave
Well-known member
Better make that three if you want to retain full frequency response. Two in parallel will only give you 6.6uF (nominal).
Go to Steve Bench's site and look at the cap test curves.
A formed Al electro is not a bad thing. I think electros get a bad rep because they are sometimes not used correctly.
Ethan I think changing the caps will be a good test.
A formed Al electro is not a bad thing. I think electros get a bad rep because they are sometimes not used correctly.
Ethan I think changing the caps will be a good test.
[quote author="NewYorkDave"]Better make that three if you want to retain full frequency response. Two in parallel will only give you 6.6uF (nominal).[/quote]
Yeah, I know, but I only have 2 of those big brick suckers :sad: They're pretty expensive. Anyhow, I"ve got a 12 position rotary switch just sitting here getting bored, so I think I'll protoboard a little testing jig to switch between several variations of different values and different kinds of caps. I've got a bunch of Orange Drops I could strap several of those in there and check it out... Will I hear a difference? Who knows... Will it kill some time on a Friday night while the woman is away for the weekend? Yes. :grin:
Yeah, I know, but I only have 2 of those big brick suckers :sad: They're pretty expensive. Anyhow, I"ve got a 12 position rotary switch just sitting here getting bored, so I think I'll protoboard a little testing jig to switch between several variations of different values and different kinds of caps. I've got a bunch of Orange Drops I could strap several of those in there and check it out... Will I hear a difference? Who knows... Will it kill some time on a Friday night while the woman is away for the weekend? Yes. :grin:
You could use both if you had room. Then add a switch labeled retro/modern.
There won't be that much difference I'm afraid. I mean
as soon as you compress, you start to squash the high end a bit.
Manly uses the high end caps in all their stuff.
Lots of good music came thru the stock LA2's eh?
There won't be that much difference I'm afraid. I mean
as soon as you compress, you start to squash the high end a bit.
Manly uses the high end caps in all their stuff.
Lots of good music came thru the stock LA2's eh?
I went thru a time trying different caps on the output, not that there was anything wrong with the original elec cap, I just wanted to see for my self,it was fun, the bigger the cap the deeper the sound, I ended up with a 15uf audio grade poly prop its 2 inch in diameter (boasting again} was 13 pounds here in uk, I also got swiches all over my LA for different things, got swich for different coloured light source in my T4 for instance, its nice to have a swich for its original sound tho.
Cheers Gary O.
Cheers Gary O.
