DIY F2 clone

[maxlorenz]

Dear Mr. Pass, Zen Mod and fellow DIYers,

I suspect some (most?) of the fine sonic attributes of tube amps come from the use of tube rectifiers...if only we could use them for SS amps...
Has anybody knowledgeable played with Thyratrons?

Thyratron Rectifiers

Thanks,
M.

 

[Zen Mod]

naah

no benefit (all drawbacks) and too complicated

even for my level of insanity

(had experience with big tube rectifiers , in cinema (Xenon))

 

[maxlorenz]

OK. Thanks. That saves me a lot of study.

Another clever trick that I've used, both in low power and high power circuits, is -ECdesigns'- stteped rectifier.
Diodes and R values can be upgraded/increased to meet desired power ratings.

Cheers,
M.

 

[oks81]

I believe answer is somewhere in article

Output impedance for my F2:
Reading, reading, reading
Found in articles:

Zen Amp: 1ohm
Zen Lightenment: 1ohm
Zen Variation 2: 1ohm
Zen Variation 8: a little less than 8ohm.
Original First Watt F2 without R13,14,15: 700ohm

On page 15, post #141 in this thread i find that output impedance for my F2 should be "big R" in parallel with output resistors R13,14,15.

I`m only using R13, and big R is 5ohm so finding output impedance=4,5ohm ?
Is this correct teacher Zen?

 

[Zen Mod]

it's here , top of page 7 :

 

[dyrevennen]

Output impedance for my F2:
Reading, reading, reading
Found in articles:

On page 15, post #141 in this thread i find that output impedance for my F2 should be "big R" in parallel with output resistors R13,14,15.

I`m only using R13, and big R is 5ohm so finding output impedance=4,5ohm ?
Is this correct teacher Zen?

Yes, that is correct. When big R and R13 is in parallel you find the total resitance, Rtot, with this equation (I saw in a previous post that you used 47 Ohms for R13):

Rtot = 1/((1/BigR) + (1/R13)

Rtot = 1/((1/5) + (1/47) = 4.519 ohms


I hope it is ok that I reply, even thought I am not master Zen

 

[Zen Mod]

 

[oks81]

Thanks a lot to both!

 

[oks81]

Still have a little bit of hum/noise from PSU..
Wath about connecting CLC with chokes like on picture?

The most suited chokes I find is the Hammond 156B (1,5mH) or 159ZJ (10mH) ?

 

[Zen Mod]

what are Rdc values for these chokes ?

 

[oks81]

what are Rdc values for these chokes ?

Info Hammond Chokes:
156B: 1,5mH RDC=0,07ohm DC-Current max=5A
159ZJ: 10mH RDC=0,16ohm DC-Current max=5A


There is also 155B at 6mH but only max current 2A (RDC=0,3ohm)
Bias in my F2 "Light" is 2A.

https://www.hammfg.com/electronics/transformers/choke/153-159

 

[Zen Mod]

more the merrier

go for 10mH

considering C as 22mF , go for CLCC

hopefully that for one channel , so you'll need two chokes

 

[oks81]

Yes, similar to drawing, one CLCC for each channel (each C=22mF) so need two chokes.
Have to look for positon in case for chokes.... Those 10mH are BIG.....

Have also read about LC but to many drawbacks for me.

Is there maybe also other manufacturers then Hammond for PSU chokes?

 

[Zen Mod]

not for my knowledge , but I'm dumpster diver , so my experience doesn't count



you certainly have some local manufacturer , just search

each factory making ballasts for neon-ish bulbs is capable to make them

 

[oks81]

Dumpster diving saves money and rain forest!

Dumpster at work only have these big chokes.....:

Need bigger house....

 

[Zen Mod]

.

 

[OllBoll]

Another possibility that worked great for me is to use a 24V SMPS. I got away with a lot smaller caps and inductors in the post SMPS CLC. The amps became small enough that I could cram in 4 amps in one box instead of 2 =)

But the main reason I did it was because I have issues with DC on my mains so the transformer hummed and I wanted to avoid building a mains circuit.

 

[oks81]

Nice OllBoll! Thanks for responce! SMPS dont take so much space. Never tried SMPS, but since I already have linear I will try to figure out to get rid of the little hum that is left.

Luckily I dont have DC issues.

 

[wdecho]

Yes, similar to drawing, one CLCC for each channel (each C=22mF) so need two chokes.
Have to look for positon in case for chokes.... Those 10mH are BIG.....

Have also read about LC but to many drawbacks for me.

Is there maybe also other manufacturers then Hammond for PSU chokes?

I've used 6hy chokes from triade in some tube builds successfully when the schematic called for 10hy. C-14X


triade magnetics chokes Triad Magnetics Inductors | Mouser

 

[oks81]

I've used 6hy chokes from triade in some tube builds successfully when the schematic called for 10hy. C-14X


triade magnetics chokes Triad Magnetics Inductors | Mouser

Ok! But in transistor amp current is much higher and voltage much lower than in tube amp, so chokes must have much lower DCR. The chokes then get really big end expensive.

Mounted today CRCC with R=0,25ohm (2x0,5ohm 10w in parallell). Much more silent now! Have space in amp for 10mH Hammond chokes but must then rearange everything inside....