Any suggestions for transformer?
One/two/three? The cost would be higher but what would be recommendable?
square or toroidal?
One/two/three? The cost would be higher but what would be recommendable?
square or toroidal?
Toroidal is cheaper than say a E core hammond, but you dont get all the secondary windings you would with a hammond. I think most of the quality trafos are to be had on your side of the pond. I am sure others will have recommendations.
I used a toroidal in my build because I had it lying around and it fitted the bill. And it has a shield between primary and secondary. But I'll never buy another again. They can couple 10-1000 times more noise from the mains into your psu. Obviously a good filter can filter it out. But what's not there need not be filtered out.
The EI has a much larger magnetic field. So that needs to taking care of. To me it is a no brainer.
I took my Salas 6V6 preamp to my main system this morning and heard hiss...that I did not hear in my computer room system (LM3886 with CSS FR125's). I suspect it is the Toroidal transformer.
Bas, you got any recommendations for EI or C core transformers for this pre. I onky know of lundahl,hammond,electraprint. Not that these are lacking. Anny magic trafo out there?
yeap people need advice here!
And an another q, you used only one transformer for all three outputs?
And an another q, you used only one transformer for all three outputs?
I would check grounding to earth if you changed environment and hear hiss and didnt do it before.
I think toroidals is ok, check if secondarys have enough dcR and if not add resistors. Nad maybe a small decoupling cap over secondarys to filter some noice.
Staffan
I dont remember exact what trannys Salas used but I guess a toroid with two (or three, depends on how you count) secondarys: one 310-0-310 and one 0-5 V. Then i guess a 10 V for rectified filament voltage.
Before choosing tranny, decide how you want to rectify. With silicon diodes in greatzbridge or with tube rectifier, or maybe a hybrid between them. That sorts out what tranny to use. Salas used tube rectifier with 5 V filament (GZ34), hence his choice of tranny I guess.
regards
Staffan
hmm, Lundahl produce air gapped C-core mains trafos, to achieve the desired mains noise rejection
but also expencive, ofcourse
regarding toroids, maybe we also talk about different quality toroids
not all the same
and some can be really noisy, in many ways
just poor quality, I guess
I see no reason why a good quality toroid should be as bad as claimed
seems more like a myth turned into a misunderstood 'fact'
but lets get the facts straight
but also expencive, ofcourse
regarding toroids, maybe we also talk about different quality toroids
not all the same
and some can be really noisy, in many ways
just poor quality, I guess
I see no reason why a good quality toroid should be as bad as claimed
seems more like a myth turned into a misunderstood 'fact'
but lets get the facts straight
I had used toroids without internal shields. Output stage tubes aren't especially looked after for noise because they are normally used with gain dividing OPTs as loads. Moving from FR speakers to tweeter equipped or horn ones there can be natural hiss of the type surfacing to notice if it ain't some gremlin coupling from filaments or PSU, carbon pot, hiss from load resistor(s) type when hot.
P.S. If you people with the gain type CCT hear no intrusive hiss on normal to high SPL speakers then there maybe reason Bas investigates his build further for hiss. Maybe you could help him by stating your system gain and your speakers SPL so he can have a clue?
Mine is toroid and had zero noise until apparently poorly implemented tube rectifier. Biggest drawback is lack of secondary voltages. This side of the pond, Antek is very good quality with shielding up to certain VA rating.
My current setup is Marantz dv8400SACD to 6v6 with about 15dB gain into F5T with about the same, I believe. I had zero hiss through my 87dB FR untis until new PSU. I think the current noise issue is related to my poor implementation and not anything else. BTW, 6V6 does not pair well with F5, nothing like DCB1, which works together very well with F5. BA3 OTOH, sounds delicious with 6V6. FYI, my wife said the same thing after listening with me gone. Always trust the wife's ears over your own🙂
My current setup is Marantz dv8400SACD to 6v6 with about 15dB gain into F5T with about the same, I believe. I had zero hiss through my 87dB FR untis until new PSU. I think the current noise issue is related to my poor implementation and not anything else. BTW, 6V6 does not pair well with F5, nothing like DCB1, which works together very well with F5. BA3 OTOH, sounds delicious with 6V6. FYI, my wife said the same thing after listening with me gone. Always trust the wife's ears over your own🙂
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Any idea what the input impedance is on an F5? Is it 100k, defined by the gate resistor in the schematic from the diyAudio thread? That should be fine with a 6V6-triode. I wonder what is causing it not to sound good?
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Personal of course. I did not intend to offend. I assume we all understand that what we hear is very subjective
that means I will have to doubt everything 😀
well, actually I do 😛
but i think that reality is that way too many 'loose statements' becomes facts way too fast and easy
once its been repeated a few times, noone knows who said it anymore, or why
from some reason , F5 prefers lesser output impedance preamps
I presume that cascoded FE F5 is less demanding
I presume that cascoded FE F5 is less demanding
hell, I know its difficult or impossible to explain, but I still want to ask the question, what kind of sound changes or 'effects' do you hear ?
btw, F5 have been known to get a bit unstable, or 'problematic', with some kinds of 'polluted' signals, yes ?
proper gounding and shielded cables are mandatory, yes ?
btw, tube preamps generally do have rolled off frequency ends, yes ?
btw, F5 have been known to get a bit unstable, or 'problematic', with some kinds of 'polluted' signals, yes ?
proper gounding and shielded cables are mandatory, yes ?
btw, tube preamps generally do have rolled off frequency ends, yes ?
I think if you consider the two power amps, it makes some sense why the BA3 would pair well with the 6V6. Both follow a similar design ideal, at least in terms of feedback. I will openly say that there was a drastically different sound out of F5T with DCB1 vs 6V6. Is tgat politically correct enough? 😉
Salas, the 6v6 is top notch, period.
ZM. Never considered thst, but it was indeed driving cascoded F5T.
Salas, the 6v6 is top notch, period.
ZM. Never considered thst, but it was indeed driving cascoded F5T.