6CG7/6FQ7 or 6SN7 are preferred for their linearity.. Just sayin'
Note: Morgan Jones "Valve Amplifiers" 3rd Edition will provide adequate confirmation.
Despite the obvious difference in mu the gain in most circuits is not as low as I suspect the OP is looking for. I actually prefer the 5751 in phono stages and the like as they are often significantly quieter than bogey 12AX7A and the JAN types are very consistent in terms of quality and reliability. Subjectively speaking they may sound a bit better in passively equalized phono stages but that depends entirely on the tubes being compared.
Disclaimer: Noting clearly that the above are only my opinions, caveat IMLE and YMMV.
6SN7 - FAR superior octal base than 12A*7 tubes.
I refuse to use minature 9 pin tubes. Octals have better contact and run cooler.
Just sayin'...
While I somewhat agree this does eliminate some very interesting tubes like the 7788, D3A/7721, 7722 and the 417A/5842 from consideration, and few would argue that these aren't stellar tubes and long lived as well. And I do love the 6SN7, 01, 12, 26 as much, but I haven't found them to be any more reliable than most noval (9 pin) types.. 😀 YMMV...
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Not at all. Most DIYers will have a range of resistors available to them. The most common set, which does not involve having huge numbers of resistors, is the standard E24 series and sets of these are readily available. 99.99% of all circuits can be built with these. When you design a circuit you might well calculate the required value but, rather than use the exact value calculated, a good designer will pick the nearest preferred (E24) value, unless there is some overriding reason not to.
If nothing else, this puts the design more immediately in the reach of most DIYers and if it is a commercial design it reduces the range of components that needs to be stocked. In other words it makes sense to use standard values.
The two particular components I asked about are non-critical and I could see no obvious reason to use such unusual values. My simple request for clarification was refused.
Cheers
Ian
You can deny it three times before the **** crows, but 5 cent resistors available off the shelf with the click of a mouse from ALL of the major parts houses can't be called "unusual" unless "unusual" is defined as "something Ian doesn't want to use." You're free to play Humpty Dumpty.
I think Kevin was pretty clear that the precise values aren't terribly critical, these are just easy and cheap values to get. You know, the OPPOSITE of unusual.😀
edit: HAH! Autocensor apparently doesn't like biblical references!
I think Kevin was pretty clear that the precise values aren't terribly critical, these are just easy and cheap values to get. You know, the OPPOSITE of unusual.😀
edit: HAH! Autocensor apparently doesn't like biblical references!
I choose resistor values that were conveniently to hand in my stash when I built and tested the prototype. Since they are so readily available here in the USA I felt no compelling urge to change them. Since most hobbyists are likely to purchase parts specifically for their projects I used values that they could easily get from their local jobber or any of the usual sources.
E-24 are 5% tolerance and in this country that meant carbon or carbon film, I'm a fan of neither having stated my preference for 1% METAL FILMS in a previous post. E-96 1% values I selected from are readily available in most of the civilized Western world. My reason for not liking carbon resistors revolves around long term stability, voltage coefficient, and excess noise (no not Johnson noise). And strangely enough I don't like the way they sound either. Metal oxide to me sound harsh and in some cases I have been able to measure significant harmonic distortion generated by these resistors - for me found in power supplies only. In a past life I replaced a lot of carbon resistors in the course of servicing defective vintage gear - I wanted to spare my clients that nuisance. I also avoid electrolytics for the same reason where practicable.
Note in many cases here at least E-24 series exact values are not always found in E-96 range parts, hence I select reasonably close STANDARD E-96 values. Circuit tolerances do not require the use of 1% parts in this particular design.
I guess I lied since I did ultimately answer the resistor question, and hopefully have given you some insight into my thought process, and what I deem important in the component selection process. Whether or not you agree is irrelevant to me.
E-24 are 5% tolerance and in this country that meant carbon or carbon film, I'm a fan of neither having stated my preference for 1% METAL FILMS in a previous post. E-96 1% values I selected from are readily available in most of the civilized Western world. My reason for not liking carbon resistors revolves around long term stability, voltage coefficient, and excess noise (no not Johnson noise). And strangely enough I don't like the way they sound either. Metal oxide to me sound harsh and in some cases I have been able to measure significant harmonic distortion generated by these resistors - for me found in power supplies only. In a past life I replaced a lot of carbon resistors in the course of servicing defective vintage gear - I wanted to spare my clients that nuisance. I also avoid electrolytics for the same reason where practicable.
Note in many cases here at least E-24 series exact values are not always found in E-96 range parts, hence I select reasonably close STANDARD E-96 values. Circuit tolerances do not require the use of 1% parts in this particular design.
I guess I lied since I did ultimately answer the resistor question, and hopefully have given you some insight into my thought process, and what I deem important in the component selection process. Whether or not you agree is irrelevant to me.
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Considering that Tube Data Sheets are suggestions rather than exact values, off the shelf closest 2% values are closer to the operating point than the design calculations are to real world operation.
There you go, that wasn't so hard was it?
The resistor series has no relation to its tolerance or what it is made from as I am sure you know. I agree with your choice of metal film resistors.
Cheers
Ian
FWIW I agree.. 2% resistors weren't that common here then.. More a European thing I think.. My local suppliers stocked 1%, 5% and 10% resistors.
Have you ever seen a 5% metal film resistor? I haven't, doesn't mean they don't exist I suppose.
E-24 is understood to be 5% and sometimes 2% tolerance. E-48 is 2%, and E-96 1% typically but I am pretty sure I have bought 0.1% in this series as well and and E-192 values come in tighter tolerances like 0.5%, 0.1% 0.01% etc. I don't think it is entirely ironclad and may depend to some extent on the specific manufacturer. The value E-x specifies the number of values in a decade span of resistance values.
Reference here: http://www.radio-electronics.com/info/data/resistor/resistor_standard_values.php
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Well, if I misinterpreted your terms "weird," "strange," and "unusual," to mean "weird, strange, and unusual," you have my apologies. Perhaps there's a difference in American usage of these terms.
You mean reduce the voltage gain? Use an unbypassed cathode resistor in a normal common cathode voltage amplifier stage.
The characteristics of each tube is determined are the physical structure. If you want somehting like a 'AU7 or 'AT7, why not just use that type?
Wow. I'll bet there are plenty of other words in the Bible that would be censored.
BTW moderators, it's just a chicken!!! 😀😀😀😀😀😀😀
😱😱😱😱😱😱😱
Maybe we can get back on topic now???
BTW moderators, it's just a chicken!!! 😀😀😀😀😀😀😀
😱😱😱😱😱😱😱
Maybe we can get back on topic now???
Good idea. Back on topic, please. That's the 12AX7, in case y'all have forgotten.- Status
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