F5 Listening Impressions & Discussion

Probably means nothing... amps sound different, that's all.

The question is, which one is "right"?

Hard to know.

Besides, if the only issue is "sound stage" width, then there's no reason to build an F5, if the sound stage width is ok already. Imo, what the F5 does (depending on your implementation) goes beyond that into "fidelity" and "timbre"...

_-_-
 
My Second F5, only a little different

Hi Everyone,

Yesterday a few of us compared my 1st F5 to a second F5 build.

1st one was a 2 transformer (Antek an-4218)mono down to the power cord. Vishay/Dale resistors, V/D power resistors and 4 standard bridge rectifers. DH labs silver on copper wire and Connex silver on copper wire. The Mosfets were IRFP9140s and IRFP140s. The amp included the thermal compensation and protection circuit.

The 2nd was built on a single transformer (Antek an-4218) feeding 4 diode bridges using Hexfreds that were filtered by independent CRC power supplies.
All wiring was Connex silver on copper, except Kimber Kable 19ga copper for inputs. All resistors were Caddock MK 132 and Mills on the power supply. This version had the thermistor and protection circuit removed. The Mosfets were IRFP9140s and IRFP140s.

The second amp was only alive for a day and a half, but there was a noticable difference in attack and decay- it was faster. The instruments were more etched in the space between the speakers. I thought at first that the "etched' sound might be due to harsh highs and lack of break-in time, but it was not annoying. I found no loss of power in the low end because of using one transformer. The bass definition was still there.
There was a bit more realism in everything it did.

The second F5 did not kill the first version. Was it worth upgrading parts, yes it was. Am I going to toss out or sell off my first version? No way!
They will make a killer bi-amp setup.

Any questions, feel free to email me.

Associated Equipement

Vinyl front end (direct drive) can't remember the brand. Clear acrylic table with beautiful wood base. Clear acrylic table has lead shot inside.
I know, I just described a hundred turn tables.
Sony DVD, modified tube output
I/O phone stage
VTL tube preamp
Gallo Nucleus Reference
Nutty expensive cabling, not crazy expensive, but just enough to make you ask, "How much again?" 🙂

Vince
 
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I think a smoother power supply can give a circuit a sense of greater ease. The new Hexfred diodes helped IMO. The new F5 doesn't seem to run out of gas or compress as much as the first version. This might be due to the diodes and lack of extra circuitry. I think the Caddock still need to break-in, as do so many other parts, and even the wiring. But, out the gate the new version just rocked!
I'm not imagining it. We A/B'ed a few tunes. All three of us heard it. Only things that chaned in the system were the source equipment and amps.
 
Tea-bag

When you say, "I dont think Caddocks are forgiving resistors." What do you mean exactly?
I interpret this as they may be clinical or critical of the sound. Like not soft or warm?
I want critical.

Yes, I have thought about the Toshibas. I held some in my hands yesterday. Not mine though.

Why not? Gone this far, right?

I have even thought about the "naked" Vishay resistors.

Lord forgive me. For I know not what I do. :angel: Well...maybe I do! :devilr:
 
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Nude Vishays are only $2 more per pc. comparing to Caddocks and MK132s tend to sound a bit edgy indeed, that's why I don't use them too much, mostly as input shunt and feedback position, everywhere else I would choose Vishays.

I also didn't find much difference switching from a single supply to dual mono.
 
Peter, do you think the "naked" Vishays are closer to wire with resistance with no added color or warmth?

I also didn't find much difference switching from a single supply to dual mono.
Yes! Exactly! Make me think I should re-work the 1st version to 1 transfo build and build a third one with......No. I better just stop here. :hypno1:
 
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In F5 manual Nelson states 1-2ohm, no problem

If 1-2ohm also means very high sensitivity speakers, no problem

If its low sensitivity speakers, maybe not so good fore any other than moderate SPL

Moderate SPL, which might still be ok fore what I would call "tactile" speakers
Well balanced speakers need not be very loud to SOUND right

I will soon present some ideas fore the Wild Burro 8"
2ways and 3ways in several variations, using the same basic box
If I manage to build F5 amp, it will be used fore devellopment, and they may become a good match
 
Are you sure about your conclusion? Could it be that the current limiting circuit is too limiting (as this was one of the differences between the two amps), as has been alluded to by people who seem to know. Does it need to be re-calculated?

Well peter didn't hear much difference. If I recall he eliminated the current limiting when he first built the mono F5's. So I'm guessing that is the difference.

As far as recalculating the current limiting. I can't imagine the master made a mistake. The F5 has only two output devices and probably had to be protected from destruction by a retail buyer or unexperienced builder.