Thanks again for your input. I'll take a look for the 6n23 and -with a little help from my friends- check the capacitors in my GM20 as well. I started using my turntable at medium gain and 100ohms. The noise and hiss level are quite low at this setting. I need to turn up the volume a bit more than for CD, but not more than 50% for enjoyable levels, so that is ok for me. For a bit more live feeling in my setup (Graaf WFB one, GM20, Diapason Adamants III) i switched the load to 500ohms, but i'll try 100 again as well.
Regards,
FG
Regards,
FG
Hi,
Film caps suffering from heat in a preamp? Really ?
What's the point in changing output caps if other caps preceding aren't changed as well ?
As for ECC88s, the best ones bar Cca are the old productions Tesla ones.
The Russian ones are fine if you can get a properly matched set.
A well designed phono preamp should not produce audible hiss at any output level ideally. Super efficient horn LS at full blast notwithstanding.
Cheers,
Film caps suffering from heat in a preamp? Really ?
What's the point in changing output caps if other caps preceding aren't changed as well ?
As for ECC88s, the best ones bar Cca are the old productions Tesla ones.
The Russian ones are fine if you can get a properly matched set.
A well designed phono preamp should not produce audible hiss at any output level ideally. Super efficient horn LS at full blast notwithstanding.
Cheers,
The GM20 is the power amp actually, but that does't run as hot as the WFB-one pre-amp. Several modifications are suggested on the internet to improve cooling of the WFB-one, however most people -including the designer- say it's really no problem for the amp itself. Just don't put anything on top
Anyway, i do believe that heat in the long run causes some wear on anything.
Regards,
FG
Anyway, i do believe that heat in the long run causes some wear on anything.
Regards,
FG
Hi,
Film caps suffering from heat in a preamp? Really ?
What's the point in changing output caps if other caps preceding aren't changed as well ?
As for ECC88s, the best ones bar Cca are the old productions Tesla ones. The Russian ones are fine if you can get a properly matched set.
A well designed phono preamp should not produce audible hiss at any output level ideally. Super efficient horn LS at full blast notwithstanding.
Cheers,
Your comment makes me think that you could be not so familiar with the Graaf production and didn't read the topic carefully enough. Otherwise when you read "GM20" you would understand that we are talking about an OTL tube main amp. As such it's well known it runs so hot that in winter works better than many stoves. And it lets you listen beautifully to music as well!
Aging is an issue for every electronic component. Very high temperatures make it much quicker. Mainly for the ones having liquid inside, like electrolythics or PIO caps, but for PP as well. So, often, who has owned a GM20 and used it thoroughly can check the brownish color of the PP caps which suffer more of high temperatures, like the ones placed closer the output tubes, that I suggested to change. When new they are light yellow. Those caps should be the GM20's only ones on the signal path and their substitution gives the best results about sound quality. Many GM 20 owners do it and I did the same with remarkable results. So I hope to be aware of what I am talking about.
When a certain level of experience is made, one learns that there is not an absolutely better tube, like CCa and Pinched Waist even more is said to be, but the one that is more suitable in the given conditions. Having tried a lot of different kinds and brands of E88CC/ECC88 on a Graaf WFB One, I know that after some time my ears commanded to remove the ones that seemed at first the most impressive, and go back to the original Sovtek 6922's or better to the Voskhod 6n23's that still were on my WFB One, when I changed it some time ago for a two chassis, separate dual mono power supplies and audio stages tube preamp.
As I said already, this is probably related to the designer choices. Moreover, I gave this advice to our Dutch friend because while now he has onboard tubes that could affect the sound of his preamp, it seems that he doesn't have the will to spend for a pair of tubes a sum higher than the whole cost of his new preamp. That said, in the ECC88 family 6n23 are known by the connoisseurs to be the best for the money. Many people say that their sound is the most closer to the western production NOS that today are sold at really high prices. Having extensively tried such tubes, not only I must agree with them, but I have to say that the best 6n23 I used gave the preamp a more pleasant and detailed sound than many Philps SQ, Mullard and Siemens E88CC, without the main shortcomings of the latters: microphony, rattling and sometimes the rather screamy sound on mids and treble.
About full tube MM/MC phono preamp stages, something that is not so easy to find in preamps of the same cost of the Graaf WFB One, whoever has had one of those perfectly knows that especially in the MC position the most part of the hiss level is given by the intrinsic noise of the tubes. Mainly the first pair in the signal path. After that, tubes with the low level of noise suitable for such purposes are getting ever more rare and expensive. As I already said, I discovered a pair of new production Gold Lion 6922 to be really silent, so maybe trying a pair could do to lower the level of hiss in an MC tube phono preamp.
Did you ever use a phono preamp of such kind?
Perhaps you are making confusion with hum in your statement. About this matter, and for its level of circuit integration, WFB One can be judged as a remarkably silent preamplifier, reflecting in that the greater experience and skill of its designer, Mr. Giovanni Mariani.
Have a nice weekend
The GM20 is the power amp actually, but that does't run as hot as the WFB-one pre-amp. Several modifications are suggested on the internet to improve cooling of the WFB-one, however most people -including the designer- say it's really no problem for the amp itself. Just don't put anything on top
Anyway, i do believe that heat in the long run causes some wear on anything.
Regards,
FG
WFB One heat is not something to be worried about. It can go on working for decades without any problem, as mine did, if nothing is placed on it.
Hi, I own and design those as well as other stuff. Thank you.
Ciao,
Quite impressive, really.
fdegrove said:
Electronic components may have a different effect for the behaviour of the equipment they are used for, according to their position in the circuit. So, the ones placed in the most critical points use to have the biggest influence.
Moreover, the designer of the GM 20 says that no other capacitors are in the signal path, being the GM 20 is a DC coupled OTL - OCL main amp with directly linked gain stages.
fdegrove said:
Never heard about real world tubes that don't need a proper matching to work at their best.
fdegrove said:
Never seen a real world tube only phono MM/MC preamp which level of hiss is not directly related to the amount of noise given by its active components. Maybe such preamps should be seen as badly designed?
Moreover, tubes are well known to be critical about hiss at low signal levels.
fdegrove said:
Being a newcomer for Graaf OTL's and preamps, FG1967 asked for advices here. I claim again here that it has been a pleasure for me trying to give him at the best of my knowledge, coming from an experience with such equipments now close to 20 years. If you see a lecture in that, your problem.
Above all, pushing someone to justify himself because he tried to help who requested advices, is usually seen as a proof of another whole series of behaviour and relationship problems.
...
Returning in topic, when talking about a GM20 and every other Graaf OTL, whoever has had one of them knows they run at very high temperature levels. As I tried to explain already, after years of heavy use, the effect on the components most exposed to the heat is to visibly cook them. At that point should be just the common sense that advices to change such an overdone component with a fresh one. When made, the average working pair of ears is able to get rather easily the effects of that change.
The same can be seen in loudspeakers as well. They usually don't have high heat in their crossover, but when after some years a PP capacitor is changed with a new one, same kind and value, the effect is rather easy to perceive. So aging use to have its consequences. Not only in amplifiers components, OTL or less, loudspeakers and so on, but even for plants, animals and human beings. It's just the evidence that cares to show this kind of things, when there is a will to take into account what happens day to day in the real world.
Regards.
Hi,
Everyone appreciates you trying to help, that's not the point.
What is the point is the remark about aging filmcaps due to heat in an OTL or preamp, whatever.
That's what triggered the "audiophile nonsense" flag with me.
I'll ignore the rest of the comments been made even though I know they're just not right either.
Cheers,
Everyone appreciates you trying to help, that's not the point.
What is the point is the remark about aging filmcaps due to heat in an OTL or preamp, whatever.
That's what triggered the "audiophile nonsense" flag with me.
I'll ignore the rest of the comments been made even though I know they're just not right either.
Cheers,
Your first comment triggered with me the flag of the "typical deaf-blind engineer". Someone who refuses to even think of taking into account the evidence of the real world occurence, and has his own religion in believing that the small part that he remembers of what is written in his manuals and textbooks is "The One And Only Truth".
But don't worry, there are so many who act exactly like you. The way of "thinking" of each of them is so indistinguishable from the others belonging to this very special kind of "human" breed, to show that there must be a giant remote control somewhere, radiating its impulses that everybody feels the need to say "I am a designer, you know?" must obey.
I have had the chance to met so many of them, this gave me ultimate demonstration that they are the true reason for so many badly sounding audio equipments and gears in the history of the audio reproduction. The same for the unease of so many audio lovers, as well, that at last abandoned the pleasure of listening to music, of course after having spent huge amounts of money to go nowhere.
That said, please return in topic, if you can, and stop bothering people and wasting band.
Thank you.
But don't worry, there are so many who act exactly like you. The way of "thinking" of each of them is so indistinguishable from the others belonging to this very special kind of "human" breed, to show that there must be a giant remote control somewhere, radiating its impulses that everybody feels the need to say "I am a designer, you know?" must obey.
I have had the chance to met so many of them, this gave me ultimate demonstration that they are the true reason for so many badly sounding audio equipments and gears in the history of the audio reproduction. The same for the unease of so many audio lovers, as well, that at last abandoned the pleasure of listening to music, of course after having spent huge amounts of money to go nowhere.
That said, please return in topic, if you can, and stop bothering people and wasting band.
Thank you.
Hallo folks,
This thread is (for me) interesting since I like schematics for MC/MD preamps using vacuum tubes. Thus, I have perfomed some PSPICE simulations using the handdrawn schematic of "tiefbassuebertragung.de" and also his (later) PDF version of the schematic. There are several differences between the first and the later version. I think the later version is rather OK, but R19L is listed as 1k5 in the handdrawn version and as 15k in the PDF. My simulations indicate that both of these values are wrong, as they result in RIAA errors. According to the simulator (Simetrix), the correct value of R19L is 7k5. Do the design gurus have any comments?
Best regards,
arensattic
This thread is (for me) interesting since I like schematics for MC/MD preamps using vacuum tubes. Thus, I have perfomed some PSPICE simulations using the handdrawn schematic of "tiefbassuebertragung.de" and also his (later) PDF version of the schematic. There are several differences between the first and the later version. I think the later version is rather OK, but R19L is listed as 1k5 in the handdrawn version and as 15k in the PDF. My simulations indicate that both of these values are wrong, as they result in RIAA errors. According to the simulator (Simetrix), the correct value of R19L is 7k5. Do the design gurus have any comments?
Best regards,
arensattic
> correct value of R19L is 7k5
Counting on thumbs:
R18L plus the impedance of the plate node driving it is around 70K. R19L should be about 1/10th of this for proper 1KHz response. Certainly not 1.5K, and probably not 15K. If you have an accurate sim, and it says 7.5K, then I accept that.
Much depends on the rp of that tube at that particular operating point.
Counting on thumbs:
R18L plus the impedance of the plate node driving it is around 70K. R19L should be about 1/10th of this for proper 1KHz response. Certainly not 1.5K, and probably not 15K. If you have an accurate sim, and it says 7.5K, then I accept that.
Much depends on the rp of that tube at that particular operating point.
I am still looking for the genuine schematics, both of WFB ONE and WFB TWO from Gruppo Ricerche Audio Alta Fedeltà.
Who can upload this ?
Hi,
I have WFB One pre. Kendeil Elko started to make problems, so as I'm going to change him I'm thinking to do an upgrade. Can you give some advice, what would be good to change, apart of tubes (I have really good ones, russian 6n23 Voskhod)? There was talk about caps near output sockets, these are 3uF caps? What about 1uF? Or 2uF caps?
And another question, can I substitute these 3uF caps with 3,3uF caps?
Best regards,
I have WFB One pre. Kendeil Elko started to make problems, so as I'm going to change him I'm thinking to do an upgrade. Can you give some advice, what would be good to change, apart of tubes (I have really good ones, russian 6n23 Voskhod)? There was talk about caps near output sockets, these are 3uF caps? What about 1uF? Or 2uF caps?
And another question, can I substitute these 3uF caps with 3,3uF caps?
Best regards,
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