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Old 15th December 2012, 08:24 AM   #12741
tfender is offline tfender  Thailand
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Very good
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Old 15th December 2012, 12:06 PM   #12742
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by lhquam View Post
How about using superconductors for the interconnects?
reducing the resistances to zero ohms, has the effect of increasing the Q of every capacitor and every inductor.
That leads to a multiplicity of perfect oscillators.

It's the damping effect of the resistances that damps the Qs of all the components and that in turn damps or even eliminates the ringing when step changes in current come along to kick the circuit into responding.
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Old 17th December 2012, 01:58 PM   #12743
udailey is offline udailey  United States
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Quote:
Originally Posted by gootee View Post
LM3886 component selection

Yes, you have to go to each of those links. But then you, too, will know...!
Each link? Did you leave one or more out or do you mean links within the thread you linked?
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Old 19th December 2012, 02:11 PM   #12744
esprit is offline esprit  United Kingdom
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Quote:
Originally Posted by AndrewT View Post
Use your best capacitors after the R of the rCRC.
Ensure the caps before the R can take the ripple current that will be imposed on them.

Many smaller capacitors usually run cooler than a few big capacitors in this first C position.
Use cheap commercial caps for that first C. They are so far removed from the Audio Signal That comes later that they have virtually no effect on Audio Quality. But they MUST operate as capacitors for the first stage filtering rC to be effective. Fakes and undersized are no good here.

Back to the caps after the R:
These supply the LF current to the amplifier. They should be adequately sized to meet that LF current demand and they should be good for Audio. That does not mean they need to be exotic AudioPhool types, but they must be good capacitors that can release charge when demanded.
Gents
I am building the power supply for my mono F5s using Civiller power supply boards version 1.0-2000-12-14,and eight Kendeil K05 105 c, 10,000uf, 40v capacitors.

I also have available some BHC ALS30A473NP100, 47,000uf, 100v, Ripple currrent 25200mA.
Are the BHC's considered a useful addition in the above F5 power supply. If so, in what location, and would this require a change of value to R9 and R10.
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Old 20th December 2012, 04:39 AM   #12745
gootee is offline gootee  United States
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Quote:
Originally Posted by udailey View Post
Each link? Did you leave one or more out or do you mean links within the thread you linked?
Within. The link actually goes to a single post and there is a set of links at the end of that post, in an attempt to save you from a lot of extraneous material.

It's worth reading.
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Old 20th December 2012, 07:12 AM   #12746
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James,

Electro caps are a bit like small planes (or cars, for that matter) - each one has a different characteristic and reliability and is built to do a different job, and so forth - the electrolytic caps are similar and they all have a different sound characteristic and the specs don't show any of this at all, unfortunately.

Now, the "sound" of the Kendeils K05s are quite different to the BHCs, regardless of the different sizes - the Kendeils will produce a noticeable heavier bass and mellow mids where the BHCs will give you a much more forward mids/tops that'll sound a bit "thin" in the bass, but are a lot "faster" (please excuse the terms) - a totally different sound my opinion here - perhaps using 94mF/rail of the 100volt BHCs will alter this, but not by much [the Rifa peh 169/200 caps are perhaps the "fastest", most dynamic of all the production electro caps, but can be tricky to "get right"].

So, as you have both types, simply allow room to try both types out - I'd suggest the K05s next to the diodes, and the BHCs as the power caps to begin with - a mixture.

I'd also suggest you dispense with the pcb and wire the caps up directly via top quality, high current solid wire, not pcb tracks, even tho they're quite thick - it makes a quite significant difference.

This amp can be altered/optomised to a surprising degree!
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Old 20th December 2012, 10:09 AM   #12747
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Quote:
Originally Posted by jameshillj View Post

This amp can be altered/optomised to a surprising degree!
Can you elaborate on the tweaking tuning possibilities?

Beyond increasing rail voltages, what else is out there to optimize the f5? (I am limited to the 25v mundorf caps in my psu, so can't further increase there)
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Old 20th December 2012, 12:44 PM   #12748
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Ah, with an equiptment lineup like you have, it's clear that you're into detail without fatigue in a big way! The 1541A-S2 in NOS?

Okay, lets start at the supply first - assume you have a good line filter like a Schaffner, etc and a "reasonable quality" power cord.

The transformers - good quality torroids (or Ei) like 300VA are the first item, fed thru a dc trap after a CL-60, as usual. [Single primary but dual secondaries/channel]

Diodes on the bridge [MSR1560G or BYV32 soft recovery Shottky]

The Mundorf caps are a fixture but can add a low drop out Cmultiplier like the one that Patrick is using in the F5X project - cost you a couple of volts but either upgrade transformer or try it as it is - very worth while addition.

UPOCC copper wire (Ohno crystal copper) - short leads to amp.

Add snubbers after the diode bridge (R+C//C "Hagerman", etc network) - plenty of discussions about this here.

An old idea, forgotten these days, but it's called "tuning the transformer winding" and you'll have to chase this one up yourself at "Promethius Audio". I think "jackinj" can add more here, but this 'tweak' can have startling changes, but is a real PIA to get right....

Okay, that's enough for the power supply for now.

Amp - okay, first is the power fets - the IRPFs, Fairchilds, Toshiba k1530/j201, or the triple k2013/j313 of Juma's. - the Toshibas would be your best bet for your system.

Now, the trickie bits - the resistors, a suggested lineup, or mixture - unfortunately not cheap.

R3,4 with Rhopoint 8G16 'econister'
R13,14 (the gate stoppers) Neohms (Zfoils, an alternative)
R11,12 (0.47R, 3/10W Isabellemnhutte PBH source resistors
R5,6 (feedback) Caddock MP930 (or possible VPR 220, power Zfoil from Group buy here)
R1,2 (jfet 10R) TRW or Caddock MP915

Extras like Mundorf Silver/gold wire (in cotton, if you prefer!), silver phono plugs, dc protection on o/p, some exotic o/p terminals, silver wire replacement for copper tracks on pcb, and so on.

You can pick an' match to your hearts content, and this is without changing your Mundorf power supply caps!

There was a recent upgrade for the Aikido by the now "banned" Bob Pragnell (Beau 2314?) via John Broskie - well recommended. Like the Tempo 2SE's.

Perhaps this might be of interest....
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Old 20th December 2012, 03:48 PM   #12749
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Quote:
Originally Posted by jameshillj View Post
Ah, with an equiptment lineup like you have, it's clear that you're into detail without fatigue in a big way! The 1541A-S2 in NOS?
thanks james. Indeed 1541aS2 in Nos mode...

Quote:
Okay, lets start at the supply first - assume you have a good line filter like a Schaffner, etc and a "reasonable quality" power cord.
i did build in a schaffner filter, but left it unconnected so far. Did you find an improvement using it?

Quote:
The transformers - good quality torroids (or Ei) like 300VA are the first item, fed thru a dc trap after a CL-60, as usual. [Single primary but dual secondaries/channel]
got it... Single transformer though... No dual mono...

[quoteDiodes on the bridge [MSR1560G or BYV32 soft recovery Shottky] [/quote]
yes, think i am using mur1560's indeed

The Mundorf caps are a fixture but can add a low drop out
Quote:
Cmultiplier like the one that Patrick is using in the F5X project - cost you a couple of volts but either upgrade transformer or try it as it is - very worth while addition.
thanks! Good idea

Quote:
UPOCC copper wire (Ohno crystal copper) - short leads to amp.

Add snubbers after the diode bridge (R+C//C "Hagerman", etc network) - plenty of discussions about this here.
i don't use snubbers... may be a good addition. Do you hear significant differences?

Quote:
An old idea, forgotten these days, but it's called "tuning the transformer winding" and you'll have to chase this one up yourself at "Promethius Audio". I think "jackinj" can add more here, but this 'tweak' can have startling changes, but is a real PIA to get right....
will have to look that one up...

Quote:
Okay, that's enough for the power supply for now.

Amp - okay, first is the power fets - the IRPFs, Fairchilds, Toshiba k1530/j201, or the triple k2013/j313 of Juma's. - the Toshibas would be your best bet for your system.
mmmm i am on 'stock' irfp's. Where can i find info on the different sonic attributes of the alternative options?

Quote:
Now, the trickie bits - the resistors, a suggested lineup, or mixture - unfortunately not cheap.

R3,4 with Rhopoint 8G16 'econister'
R13,14 (the gate stoppers) Neohms (Zfoils, an alternative)
R11,12 (0.47R, 3/10W Isabellemnhutte PBH source resistors
R5,6 (feedback) Caddock MP930 (or possible VPR 220, power Zfoil from Group buy here)
R1,2 (jfet 10R) TRW or Caddock MP915

Extras like Mundorf Silver/gold wire (in cotton, if you prefer!), silver phono plugs, dc protection on o/p, some exotic o/p terminals, silver wire replacement for copper tracks on pcb, and so on.
wow yeah.... That's a full recipe... I am using a mix of prp, dale and vishay naked resistors now, could look into some of the options you present...

Quote:
You can pick an' match to your hearts content, and this is without changing your Mundorf power supply caps!

There was a recent upgrade for the Aikido by the now "banned" Bob Pragnell (Beau 2314?) via John Broskie - well recommended. Like the Tempo 2SE's.

Perhaps this might be of interest....
definately interesting! Thanks!

I also need to look into that aikido tweak....
Aah so much still to explore!
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Old 21st December 2012, 12:51 AM   #12750
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Ah, as with 'most tweaking', some of these things also go backwards and using line filters can sometimes be "off", so it's got a bipass switch - the amp 'goes travelling' a bit and other people's mains power isn't always clean.

I have an old industrial isolation transformer in the system mains here with it's secondary centre tap to earth (so-called balanced power?) and this is quite useful for noise reduction - not much of a problem here anyway, but steadily getting worse.

I'm not convinced that separate transformers are always better, but using 2 transformers doubles the amp's capacity, halves the .... etc and this will produce changes but with all things audio, sometimes not what you wanted at all.

I have a 400va EI transformer built here (huge thing, many $s!) and it's got the extra taps on the separate sec windings at 18 & 20Vac (for using the Cmultiplier) and this is clearly a superior supply - had to bolt it to front plate - added screens, etc - monster block of iron! Completely 'over the top' but just going to extra distance to see what is possible ...

MSRs are slightly different to the MURs and so on - wouldn't get too concerned as small difference - just being a bit 'anal' here!

Not the same with the snubbers - there IS a noticeable difference but you do have to get them right, if you're wiling to go to the trouble - it's just another small thing but adding these small things up is what "tweaking" is all aboiut IMO.
And, you teach yourself to "listen better" and will cary this over into other sections like room acoustical improvements, cables, etc - an attitude thing that unfortunately, can become an obsession! Ah, I think you have caught it as well!

Just out of curiosity, try adding a Nichicon ES, KG or KZ (bipolar or superthru) across the the power lines near to the Fets on your amp board, and run separate 0volt wires back to your centre earth - BIG surprise if you haven't tried this one, particularly with the Mundorf's!
If there isn't room, try it across the power caps, the closest cap to the amp.



The differences beteen the different Fets is buried in the main thread awhile back - basically (IMO, again here) the IRFs are the basic ones, the Fairchilds have a slightly 'lighter' sound, and the Toshibas have more detail but slightly lower gain - Patrick did quite a bit of work in sorting out the way you alter the jfets to cater for the differences (or similarities actually) in transconductances in these power Fets, so it's not just a parts change, unfortunately. John walton is also pretty clued up on this, and a number of other guys have done a lot of work on this - details, hmmm!

The triple k2013/j313 of Juma's is the best of the lot, IMO, but I did this on 'veroboard' with that fancy silver wire for connections and not copper tracks, so could be different too. And biased high at 0.5A each - very nice indeed!

I see you have some Zfoils, possibly for R3,4? This is where the Rhopoints are most noticeable, and at those 10R ones at the jfets - then the Fet gate stoppers, and the the feedback resistors - that's nearly all the resistors in the circuit!
I would try the TRW/IRC replacement for the Dales - 1/2 watt ones

Oh yes, with your benign load of the Tempo's, you could possibly reduce your feedback as per the Turbo design.

There are a couple of us here that're playing with the old Phillips dac chip - with Ian's latest Fifo buffer, Patrick's CEN o/p stage, aikido with Lightspeed, etc - and so on! (my compromise to going back to vinyl!)
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