I have no turntable but would like to at some stage. I have a Arcam CD plabyer and an Ipod which I use for background music.
I guess i would like a preamp that covers line level and phono for the future.
Really, I thought the 12AU7 was the lowest gain in the 12A*7 family, could I damp it down if too high?
Thanks again guys
Before considering an ECC82/12AU7 for your linestage, take a look at Morgan Jones's measurements of them in mu follower configuration. At least then, if you decide that's what you want, you'll be aware of the poor linearity and high order distortion.
I don't know where you found that info, but I have never seen that issue. I use them in my preamp and they are dead quiet. In fact, they are much less microphonic than the 6SN7s they replaced. Hum is usually due to a poor power supply, improper wire routing or a grounding issue in my experience. Did I add that the 2C22 are also dirt cheap - I've picked up dozens for around $3-7 each for NOS WWII vintage RCA, Ken-Rad and NU.
The only drawback to the 7193 is that you have the grid and plate on top, so if they are exposed and you have kids around or curious pets they might get a jolt. I actually think they look very cool sticking out of my preamp - kind of mad-doctorish.
.
Last edited:
Hi Magz
Thanks, I should have added that some were saying they too had replaced 6AN7's with them.
I tend to agree with the cool look, certainly more intriguing than a Philips Miniwatt!
What design did you use? I found this on the web last night, (half way down page)
http://www.the-planet.org/linestage.html
Thanks, I should have added that some were saying they too had replaced 6AN7's with them.
I tend to agree with the cool look, certainly more intriguing than a Philips Miniwatt!
What design did you use? I found this on the web last night, (half way down page)
http://www.the-planet.org/linestage.html
Hi SY
I had a read last night, page 555 (third edition) "The perfect line stage" Morgan says "the best way of improving any line stage is to remove it"!
That said, what is the point in being a DIYer if we don't learn, try, have a go!
I think I will try Magz 2C22 tube (cheap, cool looking, Octal base)
Go the All Blacks!
But one way to learn is to read a good book and note what it says! Given a typical CD player and power amp, a line stage will add something: higher electricity bills, a little noise and a little distortion. Oh, and difficulty setting volume in the first few degrees of pot travel which with many pots will mean some channel imbalance too.
So what you are saying is that you would only use an active preamp for a phono stage and passive for line level?
This does make sence with regards to the noise and distortion, not so worried about the power bill though! lol
I still like the look of those 2C22 tubes 🙂
This does make sence with regards to the noise and distortion, not so worried about the power bill though! lol
I still like the look of those 2C22 tubes 🙂
You need a line stage only if you have a low output device which needs some gain added (not CD!), or you have a long interconnect cable which needs a low impedance drive. Almost all other uses of a line stage are either a waste of money, or for show, or as an effects box.
Dagwood try broskie's afc, Aikido Cathode Follower & More Triadtron for cd player use.
That e180f phono looks interesting,topology similar to Brimar 25SP1 preamplifier.
That e180f phono looks interesting,topology similar to Brimar 25SP1 preamplifier.
Hi guys,slightly off topic here,but..
I'm looking for some help with small signal pentodes ,such as the one mentioned in this thread,i have no issue if i have decent mutual characteristics -Vg1 x Ia for fixed Va and multiple Vg2 type graphs,if i only have numerical data,as is the case with some soviet tube data sheets or tube vendors,is there a calculation string to apply which will sort out the support components Ra,Rs,Cs,Rk and Ck,i have not ad much to do with the small signal pentodes,and info seems scarce.
Any help would be most welcome and appreciated.
I'm looking for some help with small signal pentodes ,such as the one mentioned in this thread,i have no issue if i have decent mutual characteristics -Vg1 x Ia for fixed Va and multiple Vg2 type graphs,if i only have numerical data,as is the case with some soviet tube data sheets or tube vendors,is there a calculation string to apply which will sort out the support components Ra,Rs,Cs,Rk and Ck,i have not ad much to do with the small signal pentodes,and info seems scarce.
Any help would be most welcome and appreciated.
Ehmm! Not sure what you are asking. Could you restate the question?
Edit: I have searched your other posts and it appears that you have previously asked for help with the basics of designing an amplification stage using a pentode, and specifically an E180F tube. I can’t help you, but hopefully others with more expertise would chip in.
Edit: I have searched your other posts and it appears that you have previously asked for help with the basics of designing an amplification stage using a pentode, and specifically an E180F tube. I can’t help you, but hopefully others with more expertise would chip in.
Last edited:
Hi Francois,and i appreciate your reply.
What i am asking is,if confronted with numerical data alone,as some vendors supply,no curves or graphic data,just values,how would this be used to design a small signal pentode stage.
I can design a small signal pentode stage if i have the mutual characteristics curves alone,though more info is always better,but from the mutual characteristics i can assign a Vg2 value then plot new anode Va x Vi vs -Vg1 curve sets.
There is also the use of the ratio "m" to re-set anode curves for a new Vg2 value,but the mutual characteristics method seems more accurate,which may or may not be as useful as one might imagine due to component tolerances,I've never made the comparison,as i've only used "m" for power tubes,and generally use dissipation to design power amps.
So failing a full detailed data sheet,which for some tubes i have is the case(sub miniature pentodes from soviet union),the data i do have is either minimal or has curve sets i have never used and are beyond my knowledge at this time,and information to decypher them seems almost lost,unless some kind soul can impart their knowledge upon me,which i am sure many would benefit from,either direct info or pointed to the relevant source.
If any one can help ,please help as the volume of small signal pentodes to be used is quite good,info for some (graphical) is lacking and EF86 tubes are over priced.
Cheers.
What i am asking is,if confronted with numerical data alone,as some vendors supply,no curves or graphic data,just values,how would this be used to design a small signal pentode stage.
I can design a small signal pentode stage if i have the mutual characteristics curves alone,though more info is always better,but from the mutual characteristics i can assign a Vg2 value then plot new anode Va x Vi vs -Vg1 curve sets.
There is also the use of the ratio "m" to re-set anode curves for a new Vg2 value,but the mutual characteristics method seems more accurate,which may or may not be as useful as one might imagine due to component tolerances,I've never made the comparison,as i've only used "m" for power tubes,and generally use dissipation to design power amps.
So failing a full detailed data sheet,which for some tubes i have is the case(sub miniature pentodes from soviet union),the data i do have is either minimal or has curve sets i have never used and are beyond my knowledge at this time,and information to decypher them seems almost lost,unless some kind soul can impart their knowledge upon me,which i am sure many would benefit from,either direct info or pointed to the relevant source.
If any one can help ,please help as the volume of small signal pentodes to be used is quite good,info for some (graphical) is lacking and EF86 tubes are over priced.
Cheers.