You fly the Serbian flag [from an earlier post]; but your mastery of the English language is downright excellent!
Please note than a DIYer of any discipline is inquisitive, craves experimentation and will seeks to implement own reproduction of any design. This DIYer will generally go where the weather suits its clothes. The bolded lyric was from the 60's or 70's by Nielsen. The complete lyric is "I am going where the sun keeps shining and the weather suits my clothes" Location and weather may have been CA.
In general, I am not in favor of gutting test equipment for the innards -- except that I do it all the time with HP465's amplifiers, one 403 a.c. voltmeter which sports new rechargeable cells and one 3400 etc. Hewlett Packard made a telecom test kit with oscillator, voltmeter and patch panel -- you find beat up ones at ham fests -- and the 353 has the following transformer:
Attachments
regarding that .... I'm rooting all these years that Papa adopts me (I would be lost in his Arc in first day , anyway ) ....... but he very cleverly avoids that all the time
you can beat that only with something like this (there are also 600ct:600ct types , looking exactly the same -all of them having toroid nickel core ) :
see more here : http://www.diyaudio.com/forums/pass-labs/174674-papas-koan-papas-surprise-2.html#post2356057
same jobbies made by Tamura and WE are having price equaling their weight in gold
and they are plain and simple repeater coils , as called in Telephone Service duty
so - here is another tip - look for old repeater coils , and stash them in quantity .....
Choky
You weren't kidding about repeaters and gold - Jensens are a steal
2 X VINTAGE 1967 WESTERN ELECTRIC 111C REPEATING COIL / REP | eBay
I know I am quite happy about the Jensens in my F4 headphone setup
Best
Bob
regarding that .... I'm rooting all these years that Papa adopts me (I would be lost in his Arc in first day , anyway ) ....... but he very cleverly avoids that all the time
Lucky you. Mr. Pass may have a personal museum of all of his creations in chrono order till 2050.
Does anyone have an idea what THD levels are achievable with the circuit?
With only the output FETS for gain devices, there is very little open-loop gain left over for negative feedback. Thus, linearity of the output FETs is crucial.
In my 1 watt into 8 ohms SPICE simulations, biased at 1.3A, I am seeing very low 2nd harmonic, but 4th-11th harmonics that are roughly as large as the 3rd. I do not know if this is a simulation artefact, or due to a deficiency in the circuit.
With only the output FETS for gain devices, there is very little open-loop gain left over for negative feedback. Thus, linearity of the output FETs is crucial.
In my 1 watt into 8 ohms SPICE simulations, biased at 1.3A, I am seeing very low 2nd harmonic, but 4th-11th harmonics that are roughly as large as the 3rd. I do not know if this is a simulation artefact, or due to a deficiency in the circuit.
little patience can't harm
we'll be given with measured performance data , judging by previous experience
btw. Spice is here pretty much useless , just because Spice doesn't know drek about exact xformer
we'll be given with measured performance data , judging by previous experience
btw. Spice is here pretty much useless , just because Spice doesn't know drek about exact xformer
Cinemag is another alternative ,good and nice price , to 80% nickel.....😉
Audio Splitter Transformers
custom:
Onetics
Slage
Eu
lundhall
sowter
Audio Splitter Transformers
custom:
Onetics
Slage
Eu
lundhall
sowter
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my experience with iron is - if you already have some , try it for anything you need ;
if you don't have them already - buy confirmed/prescribed ........ especially if they're cheap , as in this case .
can you imagine effort invested in testing 15 different types , for after DAC I/V duty ?
just to realize later that good old Beyerdynamic mic 1:7 (or 1:10) are best and pretty much easy available
catch was that I had those 15 different types in box .....
if you don't have them already - buy confirmed/prescribed ........ especially if they're cheap , as in this case .
can you imagine effort invested in testing 15 different types , for after DAC I/V duty ?
just to realize later that good old Beyerdynamic mic 1:7 (or 1:10) are best and pretty much easy available
catch was that I had those 15 different types in box .....
little patience can't harm
we'll be given with measured performance data , judging by previous experience
btw. Spice is here pretty much useless , just because Spice doesn't know drek about exact xformer
I have taken up the challenge to try fill in parts of the F6 design before Nelson releases his complete design and specs.
I agree that SPICE doesn't know much about transformers, but at this point I cannot get decent distortion results (less than .01% at 1 watt) even with an "ideal" transformer.
Alo ... Just a quick drive by before a short trip away from the soldering iron.... Anyway at night I tried a number of biasing methods and also swapped out the gate stoppers to 1k (melonhead-thanks) ....
Varying degrees of failure generally so useful nothing to report , by far the best results were using the network per post 161 (results on post 185) ..... More mulling to do these few days ...
Varying degrees of failure generally so useful nothing to report , by far the best results were using the network per post 161 (results on post 185) ..... More mulling to do these few days ...
Then you will be disappointed in the F6, as I am not even trying for lower than
0.1% at 1 watt.
😎
Pa
shoot them with THD spectra info
- "them" , because I'm ignorant and careless , regarding that
😉
isn't it somewhere around 0,1@10W ?
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If I remember correctly, it was Florida. It was the title song to the movie Midnight Cowboy.
Hmmm... I just ran simulation with SemiSouth R100, without input buffer, (nearly) ideal transformer, 6x CLG, 1.5A bias, and get under .01% THD at 1kHz into 8 ohms. I haven't tried building the JFET follower input buffer yet. The R100 has 0R47 source degeneration. I haven't studied the R100 enough to understand its thermal characteristics and its need for source degeneration. I need to order parts to build a real one.