One thing that may become a problem is the thing that is keeping "Tubes" alive.
The many variations of tubes and circuits is great for the DIYer or "tinkerer" the problem is it does not translate as nicely upstream to the manufacturers of tubes.
Case in point:
It is pretty easy to find at least a few suppliers of 6V6 and 6BQ5 variants because of the relatively common use in "Guitar & Bass" amps.
With all the variations out there most people doing an "offbeat" design are either using some sort of variation of the common Sovtek tubes or using NOS or USED tubes. As the supply of NOS uncommon tubes dries up we all are going to face the prospect of limited choices when it comes to the tubes. It is basic "supply and demand" it is extremely costly to produce tubes (relative to SS) this results in 1 of 2 things. Either low production "boutique" manufacturers that because of limited production have to charge a hefty sum, or "mass production" of a limited number of tube designs. To maximize profit in a mass production run you usually sacrifice quality. (I said USUALLY not ALWAYS)
Basically what it comes down to is as a whole the DIY community needs to try to do the following.
Minimize the number of NOS & USED stuff that is ending up in landfills. (ie, search Ebay, Craigslist, Flea Markets, Tag & Estate sales etc) and get those tubes into the market.
Brace ourselves for the prices we will expect to pay once that stuff dries up.
and be sure to make purchases from the suppliers that are struggling to stay afloat in this economy.
The many variations of tubes and circuits is great for the DIYer or "tinkerer" the problem is it does not translate as nicely upstream to the manufacturers of tubes.
Case in point:
It is pretty easy to find at least a few suppliers of 6V6 and 6BQ5 variants because of the relatively common use in "Guitar & Bass" amps.
With all the variations out there most people doing an "offbeat" design are either using some sort of variation of the common Sovtek tubes or using NOS or USED tubes. As the supply of NOS uncommon tubes dries up we all are going to face the prospect of limited choices when it comes to the tubes. It is basic "supply and demand" it is extremely costly to produce tubes (relative to SS) this results in 1 of 2 things. Either low production "boutique" manufacturers that because of limited production have to charge a hefty sum, or "mass production" of a limited number of tube designs. To maximize profit in a mass production run you usually sacrifice quality. (I said USUALLY not ALWAYS)
Basically what it comes down to is as a whole the DIY community needs to try to do the following.
Minimize the number of NOS & USED stuff that is ending up in landfills. (ie, search Ebay, Craigslist, Flea Markets, Tag & Estate sales etc) and get those tubes into the market.
Brace ourselves for the prices we will expect to pay once that stuff dries up.
and be sure to make purchases from the suppliers that are struggling to stay afloat in this economy.
Remember that hearing stuff that you never knew were there is perfectly normal with akg k701's. They're reference headphones, and known for being VERY revealing. Fine details that normal speakers mask will be revealed by k701's.
As k701's are analytical and cold I'd suggest trying the whole tube deal with a small headphone amp first. It's a moderately easy load, and tubes play good with k701's because of their nature. k701's shine when amped with a current-strong amp, and that's exactly where tubes excel. You don't have to pay up for very pricey tubes and toy around with as high voltages as if you were to build an amp for your speakers.
As k701's are analytical and cold I'd suggest trying the whole tube deal with a small headphone amp first. It's a moderately easy load, and tubes play good with k701's because of their nature. k701's shine when amped with a current-strong amp, and that's exactly where tubes excel. You don't have to pay up for very pricey tubes and toy around with as high voltages as if you were to build an amp for your speakers.
Marko25,
As intimated before, you will find a bewildering no. of options. Soon you will find contradictions, simply proving that folks' hearing is very different, even though there will be vehement protests against such a stance. Sometimes you will find topologies superceded by newer, improved topologies, to be preferred above the improvements. I am temted to quote from an article by eminent British designer and writer DRG Self:
"Most fields of technology have precise measurements of excellence; car makers compete to improve miles/hour and miles/gallon; computer manufacturers quote millions of instructions/second and cost/kilobyte, and so on. Any improvement in these objective quantities is regarded as unequivocally a step forward. In the field of audio design, many people seem to have difficulty in deciding which way forward is."
(From: "Science v. Subjectivism in Audio Engineering"; see his website.)
At the start of your 'journey', all of this just to raise awareness of genuine improvements vs. tastes/boutique designs. You can do no better than start with the AudioXpress 'Audio Classroom Series' quoted earlier, following a basic understanding of the vacuum tube. Anything by Norman Crowhurst is normative, and although I am less familiar with Marshall's work, the two contributions on power supplies there are equally instructive. That apart from the more recent book by Morgan Jones, which I understand gives quite extensive coverage.
Good luck!
As intimated before, you will find a bewildering no. of options. Soon you will find contradictions, simply proving that folks' hearing is very different, even though there will be vehement protests against such a stance. Sometimes you will find topologies superceded by newer, improved topologies, to be preferred above the improvements. I am temted to quote from an article by eminent British designer and writer DRG Self:
"Most fields of technology have precise measurements of excellence; car makers compete to improve miles/hour and miles/gallon; computer manufacturers quote millions of instructions/second and cost/kilobyte, and so on. Any improvement in these objective quantities is regarded as unequivocally a step forward. In the field of audio design, many people seem to have difficulty in deciding which way forward is."
(From: "Science v. Subjectivism in Audio Engineering"; see his website.)
At the start of your 'journey', all of this just to raise awareness of genuine improvements vs. tastes/boutique designs. You can do no better than start with the AudioXpress 'Audio Classroom Series' quoted earlier, following a basic understanding of the vacuum tube. Anything by Norman Crowhurst is normative, and although I am less familiar with Marshall's work, the two contributions on power supplies there are equally instructive. That apart from the more recent book by Morgan Jones, which I understand gives quite extensive coverage.
Good luck!
geesh!
Johan, Ok guess I loosely use Quads(a name given a circuit by its designer or manufacture) when quad(matched set of 4) would have been more accurate. Marko it can all pretty confusing: for example KT88 is technically an tetrode, whereas 6550 is a pentode. My amps and many other KT88 in Push-Pull are in pentode?
No offense Johan; philosophy and tubes::I can't hear you, Turn that s___ down Cowboy!!!!
\Ok Marko This your thread, back to it..
A push–pull output is a type of electronic circuit that can drive either a positive or a negative current into a load. A push-pull TUBE amplifier is accomplished by driving half of the output tube(s) with a phase-inverted signal that feeds the phase-inverted primary side of a center-tapped output transformer. (forgive me off main topic, threw it in to confuse- ah).
Back to Kt88 in pentode: It's actually as much historical as it is circuit topology. This little bit of history helps:
KT88 versus 6550
While developed independently on both sides
of the Atlantic, the KT88 and 6550 are broadly
speaking, electrically (and pin out) compatible,
although there are differences in the internal
construction. The KT88 has slightly higher
ratings in terms of absolute voltage (800 as
opposed to 600 Volts on the anode) but the
dissipation and electrical characteristics are
similar. Although the 6550 is classed as a
pentode, and the KT88 a tetrode (i.e. one less
electrode) there is an explanation for this.
During the time of development, Mullard were
applying for a patent on the ‘pentode’, where
the inclusion of a fifth electrode (sometimes
called the suppressor grid) connected to the
cathode was used to collect stray electrons
and reflect them back to the source. The KT –
standing for kinkless tetrode – incorporated a
form of beam shaping that actually amounted
to another electrode to achieve a similar
result, but avoided infringement of the
patent. As for the sonic differences, these days
I suspect that there is more difference
between different manufacturer’s product
than between the KT88 and 6550 per se. To
confuse the issue further, some suppliers will
produce an identical batch of valves and label
them according to the market demand; I have
had an example of each from the same
manufacturer, and breaking them open
revealed that they were absolutely identical.
From:http://www.euroaudioteam.com/pdfs/hifi+34_audio_smorgasbord.pdf
ColdCathode: Have faith, I think all of us will 'run out' first. I'm 53
Check out the relatively "new" EAT Kt88 (I'm Santa for a matched quad)
http://www.tubedistinctions.co.uk/kt88_prices.htm#top
Yes Marko, you make your own, video
http://www.tubedistinctions.co.uk/video.htm
C
Johan, Ok guess I loosely use Quads(a name given a circuit by its designer or manufacture) when quad(matched set of 4) would have been more accurate. Marko it can all pretty confusing: for example KT88 is technically an tetrode, whereas 6550 is a pentode. My amps and many other KT88 in Push-Pull are in pentode?
No offense Johan; philosophy and tubes::I can't hear you, Turn that s___ down Cowboy!!!!
\Ok Marko This your thread, back to it..
A push–pull output is a type of electronic circuit that can drive either a positive or a negative current into a load. A push-pull TUBE amplifier is accomplished by driving half of the output tube(s) with a phase-inverted signal that feeds the phase-inverted primary side of a center-tapped output transformer. (forgive me off main topic, threw it in to confuse- ah).
Back to Kt88 in pentode: It's actually as much historical as it is circuit topology. This little bit of history helps:
KT88 versus 6550
While developed independently on both sides
of the Atlantic, the KT88 and 6550 are broadly
speaking, electrically (and pin out) compatible,
although there are differences in the internal
construction. The KT88 has slightly higher
ratings in terms of absolute voltage (800 as
opposed to 600 Volts on the anode) but the
dissipation and electrical characteristics are
similar. Although the 6550 is classed as a
pentode, and the KT88 a tetrode (i.e. one less
electrode) there is an explanation for this.
During the time of development, Mullard were
applying for a patent on the ‘pentode’, where
the inclusion of a fifth electrode (sometimes
called the suppressor grid) connected to the
cathode was used to collect stray electrons
and reflect them back to the source. The KT –
standing for kinkless tetrode – incorporated a
form of beam shaping that actually amounted
to another electrode to achieve a similar
result, but avoided infringement of the
patent. As for the sonic differences, these days
I suspect that there is more difference
between different manufacturer’s product
than between the KT88 and 6550 per se. To
confuse the issue further, some suppliers will
produce an identical batch of valves and label
them according to the market demand; I have
had an example of each from the same
manufacturer, and breaking them open
revealed that they were absolutely identical.
From:http://www.euroaudioteam.com/pdfs/hifi+34_audio_smorgasbord.pdf
ColdCathode: Have faith, I think all of us will 'run out' first. I'm 53
Check out the relatively "new" EAT Kt88 (I'm Santa for a matched quad)
http://www.tubedistinctions.co.uk/kt88_prices.htm#top
Yes Marko, you make your own, video
http://www.tubedistinctions.co.uk/video.htm
C
That tube distinctions link ? OMO,
Those of us getting old and wise with onset tinnitus and other problems aren't really going to fall for cyrogenic treatment that is claimed to make a difference to the sound and is willing to pay the absurd price; there is no patent. Another snake oil remedy to ridicously tease the human brain. Why bother putting glass over the iceberg.
I'm still running 807's which are now 50 yrs old and still have 80% emission. Any need for snake oil remedy ? The output transformers are 60 yrs old and the iron hasn't changed.
richy
Those of us getting old and wise with onset tinnitus and other problems aren't really going to fall for cyrogenic treatment that is claimed to make a difference to the sound and is willing to pay the absurd price; there is no patent. Another snake oil remedy to ridicously tease the human brain. Why bother putting glass over the iceberg.
I'm still running 807's which are now 50 yrs old and still have 80% emission. Any need for snake oil remedy ? The output transformers are 60 yrs old and the iron hasn't changed.
richy
One doesn't have to be OLD to be WISE, just open minded! Not to knock Cowboy he obviously has strong opinions and beliefs about his tubes. But Cowboy, I had never heard Buckethead before so I checked out a couple youtube videos and a download or two. Pretty good for that type of music but I am pretty sure that I would have a hard time using anything of his as a track to evaluate tubes.
I have always wondered when someone is going to start marketing USED tubes as "SEASONED" or "BURNED IN"?? LOL
Marketing is such an art, it reminds me of a professor I had that told us all in class that there are 3 kinds of lies, "White Lies", "Damn Lies" and "Statistics". He was referring to the often used statistics in marketing and sales. You know like "XYZ car had the highest resale value among cars in it's class". Is it possible that XYZ car was the most expensive when new? This might indicate that even though people were paying more for it used than other models the original owner LOST more value than the others.
Re: geesh!
I saw that link also in the favourites section, its great.
I am currently working my way through the AudioXpress lessons to get myself a bit more in the know on tubes. One thing I am wondering is when I make a start wheres a good UK online place to buy all the things I need. Any direction on this would be appreciated.
This is quite true hence why I bought them
The good thing about my search is that its re-sparked my interest in building my own amp and even though I may not be able to achieve what I originally would of liked I'm sure I will have fun trying.
Equally the knowledge and support on this forum makes me feel a great deal more confident about plunging into tubes, something I have always wanted to go but daren't.
Thanks everyone
I saw that link also in the favourites section, its great.
I am currently working my way through the AudioXpress lessons to get myself a bit more in the know on tubes. One thing I am wondering is when I make a start wheres a good UK online place to buy all the things I need. Any direction on this would be appreciated.
This is quite true hence why I bought them
The good thing about my search is that its re-sparked my interest in building my own amp and even though I may not be able to achieve what I originally would of liked I'm sure I will have fun trying.
Equally the knowledge and support on this forum makes me feel a great deal more confident about plunging into tubes, something I have always wanted to go but daren't.
Thanks everyone
Re: Re: geesh!
www.hificollective.co.uk.
www.chelmervalve.co.uk
www.farnellinone.co.uk
For an expansive pocket: www.sowter.co.uk.
Maplin electronics (not sure)
RS components
richy
Marko25 said:
One thing I am wondering is when I make a start wheres a good UK online place to buy all the things I need. Any direction on this would be appreciated.
www.hificollective.co.uk.
www.chelmervalve.co.uk
www.farnellinone.co.uk
For an expansive pocket: www.sowter.co.uk.
Maplin electronics (not sure)
RS components
richy
Posts #24 and #25 ...
(Marko, I am TOTALLY off subject, but you will also learn from this here forum that us veterans afford ourselves liberties...)
Gentlemen,
Me hart be totally warmed by yon sentiments and convicshens ...
me being - respect please - all of 74 years young
almost 
From Richwalters
Cowboy,
Oops - MY bad!!!! I guess when I see quad me mono-rail brain locks onto what little content is left over between me frequency challenged earlobes. You did spell 'quad' (low case).
Now back to the topic with an effort in me creaking old bones ....
(Marko, I am TOTALLY off subject, but you will also learn from this here forum that us veterans afford ourselves liberties...)
Gentlemen,
Me hart be totally warmed by yon sentiments and convicshens ...
me being - respect please - all of 74 years young
almost From Richwalters
Cowboy,
Oops - MY bad!!!! I guess when I see quad me mono-rail brain locks onto what little content is left over between me frequency challenged earlobes. You did spell 'quad' (low case).
Now back to the topic with an effort in me creaking old bones ....
Re: geesh!
Marko,
AGAIN off-topic, but hopefully also informative to you.
Cowboy ...
Hey??
This is where the sobering truth starts regarding labeling
of tubes. I have a collection of mounted 'di-sected' typical tubes, made up from duds carefully cut open to show the innards. There are a GE KT88 and a Tung-sol 6550.
They are both very much tetrodes, two grids, beam forming elements on the sides, etc. It would therefore appear that we have two types of 6550! What brand is yours, Cowboy?
This is actually not unique; some time ago there was talk of a 'beam EL34', and somebody actually showed a photo of one! (It never became clear of what exactly the innards were supposed to belong to.)
Marko,
This may seem trivial to you, but e.g. the Russians are quite free with their designations. I won't bore you with details at this point, and I do not know about serious cases, but one sometimes do want to know whether you are purchasing a 6L6GC or a KT66.
Marko,
AGAIN off-topic, but hopefully also informative to you.
Cowboy ...
cowboy99 said:
Hey??
This is where the sobering truth starts regarding labeling
of tubes. I have a collection of mounted 'di-sected' typical tubes, made up from duds carefully cut open to show the innards. There are a GE KT88 and a Tung-sol 6550.
They are both very much tetrodes, two grids, beam forming elements on the sides, etc. It would therefore appear that we have two types of 6550! What brand is yours, Cowboy?
This is actually not unique; some time ago there was talk of a 'beam EL34', and somebody actually showed a photo of one! (It never became clear of what exactly the innards were supposed to belong to.)
Marko,
This may seem trivial to you, but e.g. the Russians are quite free with their designations. I won't bore you with details at this point, and I do not know about serious cases, but one sometimes do want to know whether you are purchasing a 6L6GC or a KT66.
'Links,are links nothing more;
ColdCathode, ( off topic)
Now, an open mind; that is something. I agree most of BH's music is of no use at all as a 'Ref' recording. I mentioned him only to set a 'stage', one that KT88 power belongs in. Give you credit for looking into him, and since you brought it up.... BH (being as 'weird' as it gets) is quickly becoming know as one of the world's greatest guitarists but is impossible to categorize; one never knows what style he'll be in next. This is a guy who put out 27 albums in 2007 alone. youtube mostly the kid favorites. 'Electric Tears' and 'Population Overdrive'(his best) are considered jazz recordings in some circles. Check him out on Wikipedia: Ozzy's comments (what a ref) show just how 'mainstream' old age can become. ... sorry,sorry ... so off topic.
Marko,
Bear with us; there are so many 'tangents' to tubes that 'off forum' is unavoidable. You've got enough to read, just funnin...
Johan,
Glad you weren't offended by my comment: Philo. is one of my favorite subjects, just that I use the 'tubes' to clear my head.
Back to topic....
My KT88's are Sovtek: a decent 'industrial grade' so I've read. They are tetrodes, in a pentode circuit; not sure if I've got that straightened out in thought yet!
As posted earlier:
"The KT standing for kinkless tetrode incorporated a form of beam shaping that actually amounted to another electrode to achieve a similar ..." result as the 6550's.
Back to the Russians: Wrong tube designations can/is a real issue: Don't want to think about plugging in the wrong tubes with some of the currents involved. Just did a 'google' on Sovtek: In 2006 an interesting/worrisome article came out in 'Stereophile'. From that article:
.....ExpoPul, a company whose factory in Saratov, Russia manufactures vacuum tubes under the brand names Sovtek, Electro-Harmonix, Tungsol, Svetlana, Mullard, and others— If the threatened hostile takeover proves successful, two-thirds of the world's supply of vacuum tubes—
http://www.stereophile.com/news/052206tubes/
In ref to above article: 1) I was not unaware that Sovtek, Electro-Harmonix, Tungsol, Svetlana, Mullard were all under the same hat? Were you?
2) It appears something happened but not the worst: Its still owned by Mike Matthews but now called the New Sensor Corporation and still manufactured in Saratov, Russia.
Ref. Wikipedia
I've considered replacing the Sovtek's but seems such a 'cr_p-shot' and with '2/3's of the worlds tube supply under one hat'. Any suggestions?
Any comments on mods to Velleman K8010's? Especially on 'modjob' done for hire by http://diyparadiso.com/mod-k80101.htm? I was horrified by what at first seemed a 'hack job' but accepting that I'm overly proud of my amps, I'm opening up to some of 'mod's he suggests.
I've rambled on long enough......Charles
ColdCathode, ( off topic)
Now, an open mind; that is something. I agree most of BH's music is of no use at all as a 'Ref' recording. I mentioned him only to set a 'stage', one that KT88 power belongs in. Give you credit for looking into him, and since you brought it up.... BH (being as 'weird' as it gets) is quickly becoming know as one of the world's greatest guitarists but is impossible to categorize; one never knows what style he'll be in next. This is a guy who put out 27 albums in 2007 alone. youtube mostly the kid favorites. 'Electric Tears' and 'Population Overdrive'(his best) are considered jazz recordings in some circles. Check him out on Wikipedia: Ozzy's comments (what a ref) show just how 'mainstream' old age can become. ... sorry,sorry ... so off topic.
Marko,
Bear with us; there are so many 'tangents' to tubes that 'off forum' is unavoidable. You've got enough to read, just funnin...
Johan,
Glad you weren't offended by my comment: Philo. is one of my favorite subjects, just that I use the 'tubes' to clear my head.
Back to topic....
My KT88's are Sovtek: a decent 'industrial grade' so I've read. They are tetrodes, in a pentode circuit; not sure if I've got that straightened out in thought yet!
As posted earlier:
"The KT standing for kinkless tetrode incorporated a form of beam shaping that actually amounted to another electrode to achieve a similar ..." result as the 6550's.
Back to the Russians: Wrong tube designations can/is a real issue: Don't want to think about plugging in the wrong tubes with some of the currents involved. Just did a 'google' on Sovtek: In 2006 an interesting/worrisome article came out in 'Stereophile'. From that article:
.....ExpoPul, a company whose factory in Saratov, Russia manufactures vacuum tubes under the brand names Sovtek, Electro-Harmonix, Tungsol, Svetlana, Mullard, and others— If the threatened hostile takeover proves successful, two-thirds of the world's supply of vacuum tubes—
http://www.stereophile.com/news/052206tubes/
In ref to above article: 1) I was not unaware that Sovtek, Electro-Harmonix, Tungsol, Svetlana, Mullard were all under the same hat? Were you?
2) It appears something happened but not the worst: Its still owned by Mike Matthews but now called the New Sensor Corporation and still manufactured in Saratov, Russia.
Ref. Wikipedia
I've considered replacing the Sovtek's but seems such a 'cr_p-shot' and with '2/3's of the worlds tube supply under one hat'. Any suggestions?
Any comments on mods to Velleman K8010's? Especially on 'modjob' done for hire by http://diyparadiso.com/mod-k80101.htm? I was horrified by what at first seemed a 'hack job' but accepting that I'm overly proud of my amps, I'm opening up to some of 'mod's he suggests.
I've rambled on long enough......Charles
My best sounding (albeit 2 WPC) amp is running a pair of NX-483's that I pulled out of an old radio I got at a flea market. There was a sticker on one of the tubes proclaiming that the tubes were last replaced in 1931. The NX-483 is a relatively unknown 5 volt filament version of the 45 used in Sparton radios in the 1920's. They sound really good, but I can't find any more of them for a reasonable price.
The effect that you are referring to is actually a defect in analog recording tape called "print through". In the old days all music was recorded on tape then mixed down, mastered, and finally transfered to vinyl. There could be some considerable delay between the mastering and the creation of the plates used to press the vinyl. During this time the master tapes were stored in a cold vault, untouched. Tape is tightly wound on a reel, such that the tape is in contact with the layer below and above it for considerable time. During this time some of the magnetic information from one layer will "print through" to the layer above and below it. This causes a general signal to noise degradation to the whole reel of tape. It is most noticible at the very beginning of the tape because the beginning of the tape has no signal recorded on it, so any print through will appear as a direct (but noisy and weak) copy of the strong signal recorded on the layer of tape below it. This was discovered in the 1950's and several techniques were used to reduce it including thicker tape, paper spacers during storage, weekly respooling, etc.
New records and most CD's made from those old tapes are usually digitally processed to remove these known artifacts, but some are not, and most of us have old records where this effect can be found.
How about "Previously Auditioned". I bought some tubes that were so marked, but the seller told me that they were actually returns that he had bought from a big Tube Store. They were cheap and all worked great.
cowboy99 said:
Hi Cowboy!
First nostalgia
- thinking back to what we played at school age before there were computers, CDs, Walkmans (Walkmen?) and the like. Cowboys! That we didn't break each others' necks ...Requested comments:
1. There were so many designs using the 'Mohican' topology that improvement by using an interstage transformer (what price?) can hardly be visualised. What about a Schmitt (long-tailed pair or LTP)? Not to condemn Benny, but when several things are changed at the same time, one needs to carefully analise which made what difference.
2. Using an ECC83 anywhere in a power amplifier is hardly the best option. Certainly not as a concertina phase splitter, and then at that required output amplitude. With respect, I must agree with B's analysis of the Velleman design. Sorry. (Draw the load lines and it shows that it would just about have overloaded as there.)
3. The use of an ECC82 in audio (despite its popularity with some) is however also debateable. You may have noticed elsewhere that it is comparatively non-linear. Small signal as here - mmmm - but rather ECC81, 12AY7 or a host of others.
4. There are two basic kinds of amplifier: Those without audible distortion, and those with low order harmonic pattern such that it 'enriches' the music (not all generated harmonics are objectionable!). If a feedbackless amplifier sounds better because of that, chances are that it is the latter kind. No feedbackless amplifier will have inaudible harmonic products. But if that is preferred ... it is your taste and money!
5. Now that I have showered on the parade, look for the silver lining. There are lots of that! My personal option would be for UL output stage (see further), LTP phase inverter using ECC81 or ECC88, and pentode input. [The eternal objection: pentodes generate more noise than triodes! Yes, about 5x more. But as power amplifier input tube this is hardly noticable unless you stick your hearing apparatus right up to the speaker. And as input tubes here, they generate about 4x lower distortion, are independent of input impedance, blah blah bloops).
6. Good quality components: Yes - but those are generally available these days. Boutique 'quality': Sorry Lone Ranger; 4 - 10x the cost, at no audible advantage. An audio amplifier is not a GHz device or super medical standard one. Beee-ware of legende urbanus.
7. As an aside: Distributed load (ultra-linear; UL) is often misunderstood. It offers the best of both triode and pentode operation. There should be little if any audible difference compared to triodes, but it gives about 2x the available output. At the same output of the maximum of triodes (other things being equal) UL gives about half the distortion - and still has further to go.
Also long post: Rather explain things well than having to go second time round.
Johan:Johan Potgieter said:
Thinking technologically:- Was that a slip between the lines ? I use 'em as cathode follower as a HP 3rd order octave filter. Distortion = NiL. Noise in such config= NiL.
Morgan Jones valve amps 3rd edit page 500 fig 7.5 shows the perfect application for an ECC83 although an ECC82 is shown. Series feedback is an excellent way of using such tubes.
I use this config alot. Replacing the 1st stage with an even higher mu tube i.e EF86 pentode and 2nd stage with a pentode as triode gives excellent performance. However M Jones misses the more important point of bootstrapping the first stage grid to split loaded cathode creating an infinitum input Z.
The beauty is that with alot of feedback (36dB) the pentode thinks it is operating optimumally in such a way that thd is negligeable whatever screen volts is set !
Richy
My take on it.
First, get some efficient speakers. At least 96db/1watt/1meter, preferably higher above 100db/1watt/1meter. (Klipsch La Scalla, Heresy, K-horn, Belles, Lowther, Altec Model 19 or Valencia, EV Sentry IVB) Many of these speakers are not made any longer and you have to find used ones. If you do this then you ease the power requirement and prevent the amp from ever going into clipping or slew rate limiting. You don't ever want this to happen! The loudspeakers are your most important purchase and you should spend most of your money there. Just insist on very efficient loudspeakers!
True Class A operation is easy to find in a preamp but very difficult to find in a power amp. There are even fewer output transformers designed that can take the 0 signal demands ( In a Class A amp maximum current flows through the primary windings in a 0 signal state). To get good frequency response in a transformer it takes very fine wire and many turns, in the off the shelf common output transformer many times too fine to withstand the 0 signal condition current flow. Class AB is much more do-able and more common because you are not cooking transformers. Class A amps are only about 30% efficient at their best. You wind up consuming 100 watts of power from the power company to put out 18 watts of Class A audio power to the speakers.
The next opinion is that single ended Class A is much more enjoyable to my ears than push pull. Push pull cancels too much. Good luck! Ray
First, get some efficient speakers. At least 96db/1watt/1meter, preferably higher above 100db/1watt/1meter. (Klipsch La Scalla, Heresy, K-horn, Belles, Lowther, Altec Model 19 or Valencia, EV Sentry IVB) Many of these speakers are not made any longer and you have to find used ones. If you do this then you ease the power requirement and prevent the amp from ever going into clipping or slew rate limiting. You don't ever want this to happen! The loudspeakers are your most important purchase and you should spend most of your money there. Just insist on very efficient loudspeakers!
True Class A operation is easy to find in a preamp but very difficult to find in a power amp. There are even fewer output transformers designed that can take the 0 signal demands ( In a Class A amp maximum current flows through the primary windings in a 0 signal state). To get good frequency response in a transformer it takes very fine wire and many turns, in the off the shelf common output transformer many times too fine to withstand the 0 signal condition current flow. Class AB is much more do-able and more common because you are not cooking transformers. Class A amps are only about 30% efficient at their best. You wind up consuming 100 watts of power from the power company to put out 18 watts of Class A audio power to the speakers.
The next opinion is that single ended Class A is much more enjoyable to my ears than push pull. Push pull cancels too much. Good luck! Ray
Re: Re: The daunting world of tubes (where to start)
The Primer
The Amity, Raven, and Aurora
New 300B PP amp completed, phase shift questions
thoglette said:
The Primer
The Amity, Raven, and Aurora
New 300B PP amp completed, phase shift questions
richwalters said:
Richy,
Er - no. I did say in power amplifiers, thinking of normal topologies either as Schmitt, or LTP, or whatever else driving power tubes like EL34, KT88 etc (highish amplitude, lowish following G1 resistor), or as input stage where the Miller capacitance could easily cause a variable loop gain h.f. slope depending on the driving input impedance, etc. I am sure you know what I mean; hope others do too.
In all these applications there always seem to be better candidates viz. ECC81, ECC88 and the like, or similar triodes, cascode circuit, pentodes or such.
Sure, I also used them in various topologies in pre-amps. I did not mean not useful in audio per se.
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