F5 power amplifier

if you want optimal sound quality, avoid all magnetic materials
and keep all kinds of metal far from trafo
not even copper, no nothing

now, if you have severe noise problem, then may be different issue
and I guess most of us have
in these times with computer switchmodes everywhere
 
If that would be the case you can't even mount a toroid in a metal housing...
There's no magic involveld with shielding transformers, some manufacturers have "audio grade" toroids with grounded metal film shields at the outside.
Noise problems with toroids are often caused by harmonics on the mains and because of the high bandwidth of toroid you also see them secundairly... Odd harmonics on the neutral of the mains (3rd, 5th etc.) is indeed a problem, and the only solution is filtering (or throwing out all inverters, led lighting, also at the neigbours 😀😀)
 
Transistors connected to an output transformer works very well. I have modified a Mcintosh 2505. Its a 75 watt integrated amp with output transformers. But, the weak link is the pre-amp. That was removed. Also, there is an on/off speaker switch that was taken out of the signal path. Added film by pass caps in power supply. Once modified this is a great sounding amp. It sounds neither tube or transistor like. But, a mix of both. This was quite a surprise since it is a very old design. I would guess that output transformer gives tube amps their musical sonic signature and when combined with transistors you get some that. You can find the 2505 on the used market for under 900 bucks. When you see the workmanship in this amp its a steal. The output transformers must be really fine quality. And to reproduce those today would cost what you can buy the whole amp for used. This is a worth while project.
 
I would guess that output transformer gives tube amps their musical sonic signature

Let's hope not. With poor OPT's maybe, but with proper hardware it's the valves that determine the sound print.

Over dinner, at the ETF last november, Menno van der Veen told me that the (basic) Amplimo output toroidals in the CentiAre (co-production of Guido Tent, Menno vd Veen and Peter van Willenswaard) manage a flat 100KHz easily.
 

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Let's hope not. With poor OPT's maybe, but with proper hardware it's the valves that determine the sound print.

Over dinner, at the ETF last november, Menno van der Veen told me that the (basic) Amplimo output toroidals in the CentiAre (co-production of Guido Tent, Menno vd Veen and Peter van Willenswaard) manage a flat 100KHz easily.

I always say, it's not what you do, it's the way that you do it.

I've use the basic OPT from Menno (Amplimo) many times with much success!

Best regards,

Audiofanatic 😉
 
Alpair 7

I was looking at a pair of these for my F5 in a pensil (tower) cabinet.
Just looking at the spec sheet, nominal power is like 20W, so I'm afraid that these might not be suitable (or you'd have to be very careful of not blowing them out of the cabinets).

Should I look elsewhere?
 
I think so.It may change sound character.My mum sold my 4 old transformers for just 6 USD 🙁 They weigh about 20 kilograms. 🙂 Too many copper is gone also
Hey umut ı was sorry to hear that.Something happened to me like that,my dad gashed my 10,000uf 100v caps.I think this is because of their ignorance about electronic stuff.

Actually ım shooting this topic for my F5.
Iam just at the starting of the project,I still havent a transformer,but I'll.
The amp will be power amp.I think I'll constuct it as on pictures.
I imagined to use kendeil caps 47.000uf 25v,and 30a rectifier,and 12p20-19n20 as a output fets.
The Pcb I use were done by Bykoz.In my opinion they are good designated(soo clear).
Iam very glad that he give me 2pcb's.

I think the layout and components are good in projects.
But anyway ı need your recommendation.
thanx...
Huseyin
 

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Hi All,

I have decided on f5 to be my first adventure into diy amps. I am situated in DK. As i understand that Cviller has no boards left, which board is the one to get ? and second any recomandations on where to get good heatsinks ?

Thank you in advance
ıf you still need pcb,you can mail to gungor.h@hotmail.com
I think a few pcb must left.