This is good news. Now I can tell everybody that I'm huffing and puffing on hills because I'm riding a cheap Univega, not because I'm old and fat.
A first 300B project...
Well, i started "safe" and used the JE Labs 300B DX circuit in my second amplifier project (the first was a 2A3).
The circuit is found here http://members.myactv.net/~je2a3/JELsc-300BDX.jpg
It worked right the first time, and I can say it performs well (for its price) compared to other 300Bs that I've heard including ASL, Airtight and Sun Audio. Also I did not have to cough out lots of money, but I did use Black Gate standard series bypass capacitors, carbon resistors, Jensen copper foil coupling capacitors, Nichicon Muse power supply capacitors, Hammond 193J choke, and custom-wound power transformers and output transformers. It used to use a Lundahl LL1648 power transformer but I "saved" it to be part of my other project.
The 300B is driving a pair of 89dB Infinity Kappa 200 with ease, no active preamp, just a DACT in a box - that's until i complete my 417A preamp though.
Well, i started "safe" and used the JE Labs 300B DX circuit in my second amplifier project (the first was a 2A3).
The circuit is found here http://members.myactv.net/~je2a3/JELsc-300BDX.jpg
It worked right the first time, and I can say it performs well (for its price) compared to other 300Bs that I've heard including ASL, Airtight and Sun Audio. Also I did not have to cough out lots of money, but I did use Black Gate standard series bypass capacitors, carbon resistors, Jensen copper foil coupling capacitors, Nichicon Muse power supply capacitors, Hammond 193J choke, and custom-wound power transformers and output transformers. It used to use a Lundahl LL1648 power transformer but I "saved" it to be part of my other project.
The 300B is driving a pair of 89dB Infinity Kappa 200 with ease, no active preamp, just a DACT in a box - that's until i complete my 417A preamp though.
It's a point of honour that I still overtake all street cyclists...
Get a frame that fits (probably smaller than you think), with cranks that fit (177.5mm for 34" legs), a handlebar stem that fits, align the ball of the foot over the pedal bearing, position the saddle fore and aft to put the knee joint over the pedal bearing with cranks horizontal, and the height of the saddle so that you don't quite straighten your leg when pedalling. You'd be amazed at the difference it all makes.
Maintain the moving parts, keep the chain clean and lubricated, and seriously pump those (narrow) tyres up!
Now imagine that you are in a race towards a crate of NOS 845...
SY said:
Get a frame that fits (probably smaller than you think), with cranks that fit (177.5mm for 34" legs), a handlebar stem that fits, align the ball of the foot over the pedal bearing, position the saddle fore and aft to put the knee joint over the pedal bearing with cranks horizontal, and the height of the saddle so that you don't quite straighten your leg when pedalling. You'd be amazed at the difference it all makes.
Maintain the moving parts, keep the chain clean and lubricated, and seriously pump those (narrow) tyres up!
Now imagine that you are in a race towards a crate of NOS 845...
EC, it's frightening that you knew the length of my legs.
My motivation runs more toward 6528s and 6LF6s than 845s, but the thought was a good one!
My motivation runs more toward 6528s and 6LF6s than 845s, but the thought was a good one!
IRON MAN....
Hi,
Yeah...just you blame me for mentioning a 6528 in a thread again, right?
Tssskkk...
Hi,
Yeah...just you blame me for mentioning a 6528 in a thread again, right?
Tssskkk...
From my reading I gathered that SE was the way to go - should I be corrected here?
Depends. Single ended has a number of advantages. I would perhaps consider balanced single-ended operation (term coined by Nelson Pass), which can be achieved with a suitable interstage transformer, or balanced inputs.
Anyway, for a first project, I guess I would recommend sticking to a single ended amplifier of 15-50W. That avoids the hairiness involved in getting push-pull to work optimally. It also about halves component cost, unless you want to go balanced.
Going for balanced single ended has the advantage of greatly reducing problems with noise, as well as making it easier to make a top class powersupply. It changes the tonal character, though. Personally, I prefer balanced single ended.
I play a variety of music so lean toward a neutral sound but on the warm side.
This is exactly what I myself prefer. And that makes me think the 6C33C-B might be for you. The 300B, 845 and 211 can get too warm for comfort. I've heard competent designs with the 6C33C-B before, and would consider their tonal character, when used properly, to be similar to a well-designed MOSFET amplifier, with a bit more soul to it.
I would like at least 8W though so that I am not limited to much in my speaker selection.
While 8W is enough for most listening, occasionally, you will find yourself wanting more. If you go for 15-50W of SE power, you should have enough juice for any reasonably well-behaved loudspeaker with 90dB/1W/1m sensitivity or better.
Depends. Single ended has a number of advantages. I would perhaps consider balanced single-ended operation (term coined by Nelson Pass), which can be achieved with a suitable interstage transformer, or balanced inputs.
Anyway, for a first project, I guess I would recommend sticking to a single ended amplifier of 15-50W. That avoids the hairiness involved in getting push-pull to work optimally. It also about halves component cost, unless you want to go balanced.
Going for balanced single ended has the advantage of greatly reducing problems with noise, as well as making it easier to make a top class powersupply. It changes the tonal character, though. Personally, I prefer balanced single ended.
I play a variety of music so lean toward a neutral sound but on the warm side.
This is exactly what I myself prefer. And that makes me think the 6C33C-B might be for you. The 300B, 845 and 211 can get too warm for comfort. I've heard competent designs with the 6C33C-B before, and would consider their tonal character, when used properly, to be similar to a well-designed MOSFET amplifier, with a bit more soul to it.
I would like at least 8W though so that I am not limited to much in my speaker selection.
While 8W is enough for most listening, occasionally, you will find yourself wanting more. If you go for 15-50W of SE power, you should have enough juice for any reasonably well-behaved loudspeaker with 90dB/1W/1m sensitivity or better.
Hi,
Opinions, opinions...
Do tubes have a sound all of their own then?
Don't think so...Driver stages may though..........
Oh...BTW, the last tubes I'd recommend to any beginner, in ascending order are: the 6C33C, 845, 211, 300B, 2A3.
Brrrr...Back to hibernating...
Cheers,
Opinions, opinions...
Do tubes have a sound all of their own then?
Don't think so...Driver stages may though..........
Oh...BTW, the last tubes I'd recommend to any beginner, in ascending order are: the 6C33C, 845, 211, 300B, 2A3.
Brrrr...Back to hibernating...
Cheers,
Re: 300B amp as first amp project
I agree with Mike C that a 300B is good first amp project.
If he wants the distinctive sound of a 300B, yes, it would be impossible to go wrong with that. If that is not what he is looking for, however, it hardly makes any sense to fork out the cash for it, does it?
And with respect to the recommendation of single manufacturer russian tubes (although by reputation some of them are excellent) ... With the Sovteks or Svetlanas, they are what they are and you are married to them for the life of the amp. And if the company starts to have problems, then availability becomes an issue.
The 6C33C-B, for example, should remain available almost indefinitely, as it is actively produced for use in the MIG29 fighter jet. But, yes, a very valid point.
As as far as power output is concerned; if its a problem then its a problem with your speakers and room, not with the amp. Since you have yet to select speakers, then this should not be a problem.
I agree 99% with this. The last 1% is the abyssal depths of subsonic heaven. 😀
The magnet systems on, e.g. the Scan-Speak woofers, increase the power demands, and give tremendous results. Then again, it depends on where his room boundary gain starts kicking in, and what volumes he will be listening to his music at.
Choose what amplifying tube to use as input, I chose a 6SN7.
Also consider the mostly equivalent 6FQ7, which at least Stax claims has superior sonics to the 6SN7. I've not tried swapping them in identical circuits.
Choose a proper driver, NOT a 6SN7, another triode like 2A3, 45, or some triode stapped pentode. I chose a 6V6GT in triode mode.
A small amount of local feedback around the coupling makes this requirement a lot less critical. And such feedback is essentially required to maintain good stereo imaging.
At lower voltages, or with an interstage transformer, or seperate power supplies, consider (in order of decreasing availability) the 6N1P (e.g. 15mA bias), 6N6P or 6N30P (e.g. 40mA bias), or 6C45P (e.g. 80mA bias). All of these are excellent sounding, though the 6N30P can easily become too warm, unless used with care. (Both sonically and literally. We're talking 4W per section in a standard miniature envelope here, and the 6C45P does 10W.)
As to the power supply suggestion... you don't think that's a bit over the edge for his first project? Most of the performance gain can be realized with the following, simple approach.. Use a hybrid graetz bridge (with a regular rectifier and two high voltage diodes), followed by small resistors on each of the out-leads. Then follows a polypropylene capacitor of a suitable value for the chosen rectifier. After that, an inductor with high Q and low stray capacitance. Next, a high quality high-voltage electrolytic capacitor with a bit of series resistance. Paralell a valve based AC shunt. Use a small resistor in the path to the different anodes, and decouple locally with small caps. Make sure all the poles in the supply form some nice alignment, like Bessel or so.
On the topic of the 300B, don't get me wrong. I fully realize that it can be made to sound orders of magnitude better than people usually do. I just feel that the inherent potential of certain other valves provides better value for money, which can then be spent elsewhere. (As you pointed out, you prefer the 2A3, which is essentially two 45's in parallell, to the 300B, were the power sufficient.)
I agree with Mike C that a 300B is good first amp project.
If he wants the distinctive sound of a 300B, yes, it would be impossible to go wrong with that. If that is not what he is looking for, however, it hardly makes any sense to fork out the cash for it, does it?
And with respect to the recommendation of single manufacturer russian tubes (although by reputation some of them are excellent) ... With the Sovteks or Svetlanas, they are what they are and you are married to them for the life of the amp. And if the company starts to have problems, then availability becomes an issue.
The 6C33C-B, for example, should remain available almost indefinitely, as it is actively produced for use in the MIG29 fighter jet. But, yes, a very valid point.
As as far as power output is concerned; if its a problem then its a problem with your speakers and room, not with the amp. Since you have yet to select speakers, then this should not be a problem.
I agree 99% with this. The last 1% is the abyssal depths of subsonic heaven. 😀
The magnet systems on, e.g. the Scan-Speak woofers, increase the power demands, and give tremendous results. Then again, it depends on where his room boundary gain starts kicking in, and what volumes he will be listening to his music at.
Choose what amplifying tube to use as input, I chose a 6SN7.
Also consider the mostly equivalent 6FQ7, which at least Stax claims has superior sonics to the 6SN7. I've not tried swapping them in identical circuits.
Choose a proper driver, NOT a 6SN7, another triode like 2A3, 45, or some triode stapped pentode. I chose a 6V6GT in triode mode.
A small amount of local feedback around the coupling makes this requirement a lot less critical. And such feedback is essentially required to maintain good stereo imaging.
At lower voltages, or with an interstage transformer, or seperate power supplies, consider (in order of decreasing availability) the 6N1P (e.g. 15mA bias), 6N6P or 6N30P (e.g. 40mA bias), or 6C45P (e.g. 80mA bias). All of these are excellent sounding, though the 6N30P can easily become too warm, unless used with care. (Both sonically and literally. We're talking 4W per section in a standard miniature envelope here, and the 6C45P does 10W.)
As to the power supply suggestion... you don't think that's a bit over the edge for his first project? Most of the performance gain can be realized with the following, simple approach.. Use a hybrid graetz bridge (with a regular rectifier and two high voltage diodes), followed by small resistors on each of the out-leads. Then follows a polypropylene capacitor of a suitable value for the chosen rectifier. After that, an inductor with high Q and low stray capacitance. Next, a high quality high-voltage electrolytic capacitor with a bit of series resistance. Paralell a valve based AC shunt. Use a small resistor in the path to the different anodes, and decouple locally with small caps. Make sure all the poles in the supply form some nice alignment, like Bessel or so.
On the topic of the 300B, don't get me wrong. I fully realize that it can be made to sound orders of magnitude better than people usually do. I just feel that the inherent potential of certain other valves provides better value for money, which can then be spent elsewhere. (As you pointed out, you prefer the 2A3, which is essentially two 45's in parallell, to the 300B, were the power sufficient.)
Opinions, opinions...
Do tubes have a sound all of their own then?
Well, they do have a 'first order' sound, but the second order effects are usually a greater contributor to the net result. Which also supports my claim that there are more cost effective alternatives.
Oh...BTW, the last tubes I'd recommend to any beginner, in ascending order are: the 6C33C, 845, 211, 300B, 2A3.
I take it you mean order of decreasing difficulty to use properly?
Speaking of which.. Since you're undoubtedly more knowledgeable than me on this topic, what valves would you recommend? How about e.g. the 6550?
Do tubes have a sound all of their own then?
Well, they do have a 'first order' sound, but the second order effects are usually a greater contributor to the net result. Which also supports my claim that there are more cost effective alternatives.
Oh...BTW, the last tubes I'd recommend to any beginner, in ascending order are: the 6C33C, 845, 211, 300B, 2A3.
I take it you mean order of decreasing difficulty to use properly?
Speaking of which.. Since you're undoubtedly more knowledgeable than me on this topic, what valves would you recommend? How about e.g. the 6550?
Hey,....
You don't want me to tell you to go suck a lutefisk?
Just kidding, I'll get back to you...Gently.
It's 6 AM and I do need my beauty sleep.
Tubes are very kind animals, so am I, so I must be a tube...
Logic sux... 😉
You don't want me to tell you to go suck a lutefisk?
Just kidding, I'll get back to you...Gently.
It's 6 AM and I do need my beauty sleep.
Tubes are very kind animals, so am I, so I must be a tube...
Logic sux... 😉
I'm not sure what you mean by the "hairiness" of a push-pull. They're really more forgiving in many respects- PS rejection, for example. And given that they rule in the areas of efficiency, output Z, distortion, and power, I'm not sure what the "advantages" of SE are- unless, as you say about the 300B, you're looking for an amplifier that has a sound.
Interesting discussion.
One output tube not mentioned here (I believe) is the Svetlana SV811-3. It has extremely linear curves, most impressive.
This is a beautiful looking tube, plate dissipation 65W, mu 3 and rp of 1900R. I have two, but have not yet taken the deep breath necessary to start the project. To my mind they look a lot like a scaled down 845, and they cost me $US30 apiece, a bargain.
Are they still made? Any one used them in SE/PP? By my reckoning they should be good for at least 15W in SET.
Cheers,
Hugh
One output tube not mentioned here (I believe) is the Svetlana SV811-3. It has extremely linear curves, most impressive.
This is a beautiful looking tube, plate dissipation 65W, mu 3 and rp of 1900R. I have two, but have not yet taken the deep breath necessary to start the project. To my mind they look a lot like a scaled down 845, and they cost me $US30 apiece, a bargain.
Are they still made? Any one used them in SE/PP? By my reckoning they should be good for at least 15W in SET.
Cheers,
Hugh
final amp?
I just came from the CES and T.H.E. Show and heard alot, alot of amps, including many DHT 45, 300b, 845, and a few other DHT amps. All the amps, whether DHT, IDTs (indirectly heated, wired triodes), or otherwise had similar if not exactly the same rooms. I also take it that each company had the sound they wanted to convey. They all had the same chance to get it right. Only a handful were really accurate and sounded emotionally right.
The DHT amps were just as expensive as others (especially the tubes) and of the handful with honest accurate reproduction, the DHTs just didn't make it. The inner detail and liveliness just wasn't there as others such as with Atmasphere, EL34, Kt88 amps were clearly more accurate, sonically, in the mids and elsewhere.
I am afraid you will be constantly changing the design trying to get the sonics right, and spending your savings trying to do so.
I would stay with a reasonably priced tube and experiment for awhile.
My advice is to listen first before purchasing if you really want a world class amp. Otherwise, one will be spending and spending until one hits the right design and sound. After all one does'nt know what it will sound like till one hears it. If one wants to experiment, then that is a different story of course.
Steve
SAS Audio Labs
I just came from the CES and T.H.E. Show and heard alot, alot of amps, including many DHT 45, 300b, 845, and a few other DHT amps. All the amps, whether DHT, IDTs (indirectly heated, wired triodes), or otherwise had similar if not exactly the same rooms. I also take it that each company had the sound they wanted to convey. They all had the same chance to get it right. Only a handful were really accurate and sounded emotionally right.
The DHT amps were just as expensive as others (especially the tubes) and of the handful with honest accurate reproduction, the DHTs just didn't make it. The inner detail and liveliness just wasn't there as others such as with Atmasphere, EL34, Kt88 amps were clearly more accurate, sonically, in the mids and elsewhere.
I am afraid you will be constantly changing the design trying to get the sonics right, and spending your savings trying to do so.
I would stay with a reasonably priced tube and experiment for awhile.
My advice is to listen first before purchasing if you really want a world class amp. Otherwise, one will be spending and spending until one hits the right design and sound. After all one does'nt know what it will sound like till one hears it. If one wants to experiment, then that is a different story of course.
Steve
SAS Audio Labs
The "sound" of SE
There seem to be a lot of feelings about what topologies should sound like on this thread.
It is assumed that SE will sound warm: it doesn't sound cold: how it sounds exactly, depends on how much of the curve you use. This will depend on the efficiency of the speakers, the environment, the listening level, and the kind of music.
I have repaired quite a few SE and P_P amps over the past year, and always test them "for real" using my own source and speakers. There can be a distinct difference between SE & P-P, but where the difference is greatest, I consider neither to be giving accurate or pleasant reproduction. I've heard nice warm 2A3 SE's (that wouldn't sound so warm into horns for example), and some quite unpleasant sounding P-P's. So called "ultralinear" class AB sounds the worst to me.
Feedback arguments aside, it cannot be denied that DHT valves have the lowest distortion. If you must 🙄 add feedback, at least start with the most linear system, otherwise you might as well use BJT's.
The best sounding amp I've heard on my system so far was a 211SE. This was capable of delivering the full 18w, but when running at normal volume levels, it was nearest I've ever heard in creating the illusion of "being there".
I don't believe valves have a sound of their own. It's a complex mix of topology and environment.
There seem to be a lot of feelings about what topologies should sound like on this thread.
It is assumed that SE will sound warm: it doesn't sound cold: how it sounds exactly, depends on how much of the curve you use. This will depend on the efficiency of the speakers, the environment, the listening level, and the kind of music.
I have repaired quite a few SE and P_P amps over the past year, and always test them "for real" using my own source and speakers. There can be a distinct difference between SE & P-P, but where the difference is greatest, I consider neither to be giving accurate or pleasant reproduction. I've heard nice warm 2A3 SE's (that wouldn't sound so warm into horns for example), and some quite unpleasant sounding P-P's. So called "ultralinear" class AB sounds the worst to me.
Feedback arguments aside, it cannot be denied that DHT valves have the lowest distortion. If you must 🙄 add feedback, at least start with the most linear system, otherwise you might as well use BJT's.
The best sounding amp I've heard on my system so far was a 211SE. This was capable of delivering the full 18w, but when running at normal volume levels, it was nearest I've ever heard in creating the illusion of "being there".
I don't believe valves have a sound of their own. It's a complex mix of topology and environment.
All this feedback is fantastic, I hope clarity will surface from my increased confusion.
There appears to be a thread that some valves are uneconomical ie they cost disproportionately more than their quality dictates. I am really not fussed about the tube costs, in all but the most rediculous instance eg WE300B the cost is insignificant to the cost of quality iron - at least that is my calculators thought.
I'm going to do a hifi store crawl soon to listen to a few commercial amps and just listen to what the different options I can find actually sound like.
Thanks
Ralf
There appears to be a thread that some valves are uneconomical ie they cost disproportionately more than their quality dictates. I am really not fussed about the tube costs, in all but the most rediculous instance eg WE300B the cost is insignificant to the cost of quality iron - at least that is my calculators thought.
I'm going to do a hifi store crawl soon to listen to a few commercial amps and just listen to what the different options I can find actually sound like.
Thanks
Ralf
Don't forget:
You only buy the iron once, but the valves have a finite lifetime, output valves especially.
You only buy the iron once, but the valves have a finite lifetime, output valves especially.
Re: Re: Re: Build with 300B or something else???
Konnichiwa,
While I know the "traditional" Designs (I kinda like the Quicksilver Amp's quite well), specific comparisons for SE where drawn with "non-traditional" designs, though I yet have to try "LM3" Mode.
I'm not sure how you get to associate "Excellent" sound with "Transistorish" sound. Yes, in "tradtional" Amp's the EL34 sounds warm and dark (not a "bad" thing per se) and 6550/KT88 rather steely (using the same Amp). In SE I find all "trioded pentodes" to give less than stellar sound, lacking resolution, involvement and pace, plus usually a less than well defined bass (less easy to follow base lines in the music).
"Pedestrian" is used here in the same way it usally is. Like "Car vs. Pedestrian". The sound is "slow", "opaque" and in general as if a few veils have been dropped in front of your speakers.
Oh, I should mention, all speakers used in recent years with me where of 95db/W/m (and not 95db/2.83V/m & 2 Ohm loads) or higher (up to 105db/W/m) in the majority, with only one or two of the common power hungry designerrors commonly sold as "High Fidelity" speaker).
The WE 300B is LESS coloured than a 211 and notably less than an 845, based on the Amplifiers I heard them in (including some from Kondo that have pretty much identical driver circuitry and identical component quality giving a somewhat level playing field). The 211 tends towards steelyness (like the KT88) and the 845 just sinmply sound opaque to my ears.
Involvement, the ability to clearly resolve complex musical lines allowing me to hear the technique and instrument used, basically something that represents an "open window" pardigm, with minimal editorialising.
No, I heard the Graaf GM20 (so-so, like most OTL's), the LAMM SE (pretty good, but if I don't need extra power I take a 300B) and a PP DIY Unit, supposedly simmilar to BAT, wouldn't know (maybe the best 6S33 Amp so far). As said, I have little experience with the 6S33 and like with the Svetlana 572/811 "Dash" Series you don't get a choice of brands and are limited to a potentially early running out supply, also suitable Output transformers are not exactly common.
So, I'd still recommend a 300B Amp to anyone who wants to build. Get the iron right and you will be able to convert later to 2A3 or 45 if you find you like. Most milage for a given investment, unless you insist on using low resolution, high distortion and compression so-called "High Fidelity" speakers.
Sayonara
Konnichiwa,
angel said:
While I know the "traditional" Designs (I kinda like the Quicksilver Amp's quite well), specific comparisons for SE where drawn with "non-traditional" designs, though I yet have to try "LM3" Mode.
angel said:
I'm not sure how you get to associate "Excellent" sound with "Transistorish" sound. Yes, in "tradtional" Amp's the EL34 sounds warm and dark (not a "bad" thing per se) and 6550/KT88 rather steely (using the same Amp). In SE I find all "trioded pentodes" to give less than stellar sound, lacking resolution, involvement and pace, plus usually a less than well defined bass (less easy to follow base lines in the music).
angel said:
"Pedestrian" is used here in the same way it usally is. Like "Car vs. Pedestrian". The sound is "slow", "opaque" and in general as if a few veils have been dropped in front of your speakers.
Oh, I should mention, all speakers used in recent years with me where of 95db/W/m (and not 95db/2.83V/m & 2 Ohm loads) or higher (up to 105db/W/m) in the majority, with only one or two of the common power hungry designerrors commonly sold as "High Fidelity" speaker).
angel said:
The WE 300B is LESS coloured than a 211 and notably less than an 845, based on the Amplifiers I heard them in (including some from Kondo that have pretty much identical driver circuitry and identical component quality giving a somewhat level playing field). The 211 tends towards steelyness (like the KT88) and the 845 just sinmply sound opaque to my ears.
angel said:
Involvement, the ability to clearly resolve complex musical lines allowing me to hear the technique and instrument used, basically something that represents an "open window" pardigm, with minimal editorialising.
angel said:
No, I heard the Graaf GM20 (so-so, like most OTL's), the LAMM SE (pretty good, but if I don't need extra power I take a 300B) and a PP DIY Unit, supposedly simmilar to BAT, wouldn't know (maybe the best 6S33 Amp so far). As said, I have little experience with the 6S33 and like with the Svetlana 572/811 "Dash" Series you don't get a choice of brands and are limited to a potentially early running out supply, also suitable Output transformers are not exactly common.
So, I'd still recommend a 300B Amp to anyone who wants to build. Get the iron right and you will be able to convert later to 2A3 or 45 if you find you like. Most milage for a given investment, unless you insist on using low resolution, high distortion and compression so-called "High Fidelity" speakers.
Sayonara
...decisions, decisions, decisions....
I find that the performance of two types of amplifier to be quite loudspeaker dependent and one type of amplifier to be pretty consistent regardless of loudspeaker (within the amplifier power limitations)...
I find SE amplifiers with or without feedback and PP amplifiers with feedback to vary their performance according to loudspeaker type and push pull non-feedback amplifiers to be pretty consistent.
All feedback referred to above is global feedback derived from the amplifier output. Non global feedback or global feedback not taken from the output doesn't necessarily show this variability.
So I mainly design and make PP fully balanced designs without feedback.
I find that some IHTs beat most DHTs i.e ECL82 (in triode mode) just about beats or equals any DHT - I rate it with 6B4Gs (ie just ahead of 2A3s). This seems to be the exception that proves the rule as most DHTs beat IHTs - especially KT88, 6550, EL34, 6l6s. EL84 is good one though as is the 807 family and 6V6.
I don't rate 300Bs. I just can't get them to be neutral. I like 845s and 211s for higher power situations. Wish I could try 212s or 849s!
I recently tried 211s in a cathode follower push pull arrangement and got the surprise of my life! They where astonishingly good and measure incredibly low distortion if kept in Class A. THD at full power (20W) was 0.07 max. and practically all third harmonic with just a touch of 2nd and fifth. Finding a driver that would swing 600Vpp with similar performance is the problem. I'm using 1:4 IT from push-pull driver stage tuned for low distortion. Thank God the CF doesn't suffer from Millers cap! This gave a nice low output impedance that helped this amp drive a pretty reactive speaker at work. First time a valve amp had beaten a good ss amp on that speaker! Now I can hold my head up high at work with my engineers again...
ciao
James
I find that the performance of two types of amplifier to be quite loudspeaker dependent and one type of amplifier to be pretty consistent regardless of loudspeaker (within the amplifier power limitations)...
I find SE amplifiers with or without feedback and PP amplifiers with feedback to vary their performance according to loudspeaker type and push pull non-feedback amplifiers to be pretty consistent.
All feedback referred to above is global feedback derived from the amplifier output. Non global feedback or global feedback not taken from the output doesn't necessarily show this variability.
So I mainly design and make PP fully balanced designs without feedback.
I find that some IHTs beat most DHTs i.e ECL82 (in triode mode) just about beats or equals any DHT - I rate it with 6B4Gs (ie just ahead of 2A3s). This seems to be the exception that proves the rule as most DHTs beat IHTs - especially KT88, 6550, EL34, 6l6s. EL84 is good one though as is the 807 family and 6V6.
I don't rate 300Bs. I just can't get them to be neutral. I like 845s and 211s for higher power situations. Wish I could try 212s or 849s!
I recently tried 211s in a cathode follower push pull arrangement and got the surprise of my life! They where astonishingly good and measure incredibly low distortion if kept in Class A. THD at full power (20W) was 0.07 max. and practically all third harmonic with just a touch of 2nd and fifth. Finding a driver that would swing 600Vpp with similar performance is the problem. I'm using 1:4 IT from push-pull driver stage tuned for low distortion. Thank God the CF doesn't suffer from Millers cap! This gave a nice low output impedance that helped this amp drive a pretty reactive speaker at work. First time a valve amp had beaten a good ss amp on that speaker! Now I can hold my head up high at work with my engineers again...
ciao
James
Re: Re: 300B SETs
🙂
Really funny you should say that, as (here I may lose any street cred I may have built up) I've listened to Dido's latest CD and I like it.
But where she can't quite manage the high notes it comes out as something resembling white noise!
Well, the system doesn't make this white noise magic; but (street cred in even more danger!) there is some magic on that CD.
My 300B amp certainly does not put a rosy glow over everything; it's highly sensitive to program quality! Last night, Mozart piano concerto 21; Play Bach no 2; Astrud Gilberto 'Look to the Rainbow', all LP. A tough job, having to listen to such things as I run Isabelle in, but somebody's got to do it! 😀
Agreed totally.
But with dozens of people describing 300B amps, you can average out the comments or look for consensus.
Oh, I don't go to concerts every week; roughly every month though.
Yes, agreed ... I put it in ... I try not to put unecessary words in, or unecessary components into my projects. 🙂
Good point - I love the last comment!
An uncommon valve is still a tough choice for a first project though, less of a known quantity?
For what it's worth, my 300B driver stage is a triode/pentode Kimmel mu stage of 6SL7 and E83F. With 490V on it, it can swing 150V either way, highly linear, from about 400 ohm impedance. All confirmed on the scope.
No, it doesn't make white noise sound good; but it seems highly neutral, good quality, reflects the quality of the source material, and makes music.
Nice to talk, I respect your views and don't really disagree. 🙂
angel said:
🙂
Really funny you should say that, as (here I may lose any street cred I may have built up) I've listened to Dido's latest CD and I like it.
But where she can't quite manage the high notes it comes out as something resembling white noise!
Well, the system doesn't make this white noise magic; but (street cred in even more danger!) there is some magic on that CD.
My 300B amp certainly does not put a rosy glow over everything; it's highly sensitive to program quality! Last night, Mozart piano concerto 21; Play Bach no 2; Astrud Gilberto 'Look to the Rainbow', all LP. A tough job, having to listen to such things as I run Isabelle in, but somebody's got to do it! 😀
Agreed totally.
But with dozens of people describing 300B amps, you can average out the comments or look for consensus.
Oh, I don't go to concerts every week; roughly every month though.
Yes, agreed ... I put it in ... I try not to put unecessary words in, or unecessary components into my projects. 🙂
Good point - I love the last comment!
An uncommon valve is still a tough choice for a first project though, less of a known quantity?
For what it's worth, my 300B driver stage is a triode/pentode Kimmel mu stage of 6SL7 and E83F. With 490V on it, it can swing 150V either way, highly linear, from about 400 ohm impedance. All confirmed on the scope.
No, it doesn't make white noise sound good; but it seems highly neutral, good quality, reflects the quality of the source material, and makes music.
Nice to talk, I respect your views and don't really disagree. 🙂
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