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Hi,
all these preamps have been around for a while now and I guess some of you have been able to compare them to some of the "best" production preamps,so it would be fun to have some thoughts on how you believe they compare ? . I know there are no "best" and that sound usually are very subjective,but I would like to hear your subjective thoughts and don't be afraid to brag about your own project :-)I'm about to order parts for one of these amps,and I think I will go for the Raven,unless someone in here manages to change my mind;-).
I have recently had some very good preamps like EAR 864,DIY Hifi Supply TRAM,Audio Note M3 line kit signature version with C-core OPT, and the one I have left,Eastern Electric Minimax.
The Raven will be a little different than all these 4 since its push-pull,and it can be interesting to hear if that brings anything new to the table.....
I also have a plan to build the Karna amplifier,so a Raven can maybe be a way for me to find out if thats a design/sound-philosophy that will enhance my MUSICAL experience,before I spend very big bucks on the Karna parts :-) I've had my share of so called "high-end" products that made some of my absolute favourite records sound like shit,and thats NOT what I'm looking for.Luckily I've heard good stuff like Audio Note that pull out more REAL information from my records and because of that in fact make records that I thought were very bad recorded now become MORE musical enjoyable,and thats what I'm looking for!So any thoughts on differences between some of these and other good DIY designs, and maybe comparsion made with big bucks finished products like say the Audio Note M10 :-) ?
BTW,since I'm from Norway we have 230 Volt and 50Hertz net specs.Do you think that can give me any noise/hum problems from constructions like Raven which is voiced with 120 and 60(?)Hz ?
Follow Ups:
I built one of these using information from Allen's Cookbook and various places on the Net.It's far from being a kit project, but with plenty of patience and dedication it's possible to build something that should come close to an official VSE kit for a lot less money (though the latter certainly looks far better than mine!).
As far as the sound goes, the rest of my system downstream from the preamp is definitely not transparent enough to give the full measure of my RTP3, but I am extremely pleased with the sound.
There is a very positive review of the commercial RTP3D in a comparison that includes the Kondo KSL-M7:
http://www.positive-feedback.com/Issue26/preamps.htm
Alex
Also available as a full kit is the SVP-1 unbalanced preamp, indeed ALL our products are available as full kits!.Mail me privately for more details as the "Kit" brochure is not yet up on the website.
If you want the best sound, I (and others) would suggest using directly heated triodes. There's a bit of an art to chosing and using them, but they don't have to be a fright for the constructor. You need a good DC supply for each tube (current source best), and to get the best out of them a 100k stepped attenuator on the input and a nice Lundahl (or other) transformer on the output. Virtually nothing in all audio is better than or even as good as this. But even better is to get a differential DAC like the RAKK DAC and put it straight into the grids of a differential DHT stage, with 75 ohm resistors from each leg (+ and -) to earth before the grid stoppers. That's astounding, and not too expensive at all.For the DHT think 12A, 01A, 26 globe, any of those. One of the least microphonic is probably the VT-67. You need a very dead chassis that doesn't ring at all, but if you use DHTs in differential rather than SE you should be fine. Transformer out gives you the choice of SE or balanced to the amp. If you have a push pull amp it's useful to change it to balanced operation and use a shunt attenuator which you can easily build yourself with really good quality resistors. Kevin Carter can help you out with all this on the K&K forum - he has a 26 line stage and information on all the right Lundahls, plus of course the RAKK DAC which is extremely detailed and clean sounding - a real joy.
Any suggestions for what output transformer to use for differential 26 stage?Sounds very tempting
I'm using a LL1660 which seems to work fine. LL1689 works fine as a stepdown. That's my experience.
Andy, because Rune asked about Aikido, I would add that I have built an Aikido stage using DHTs without resorting to DC on the filaments. AC hum on the filaments of the DHTs cancels in the Aikido circuit. In my implementation the microphonics were under control too, which I believe to be another cancellation effect.AC on filaments should be easier to implement than the various DC ideas. However, there is easier and there is easy -- the rub is that you need separate AC filament sources for each DHT in the circuit (I have used separate hum pots with each, too). My experiments have been with 26s, for which four 1.5v sources are needed. I have self wound a little toroid to see if there is a cheap and relatively easy way to get four separate 1.5v power sources. Not yet tested it in circuit.
Rune asked about the sound. Like any proud papa, I like my invention, and have listened to it daily as a headphone amp for five months. But, I cannot offer a comparison of anything else to it, other than my earlier attempts. It is better than any my earlier implementations of headphone amps.
Thanks alot Andy for sharing!I have no electronic background besides I've built some Audio Note kits from good build descriptions,so I can use a solder iron and do some simple measuring:-) ,but besides that most of the technical aspects are totally new ground for me.But I've found out that there is only one way to really learn and thats by practice,and I also learn a lot from friendly guys like you that are willing to share! :-)
There is one thing if you don't mind...I've seen alot of talk about current sources and I have done some quick search and reading,but I didn't understand it.Can you in an easy way explain what it is? Or some good links for me to read about it? This might be a stupid observation/statement but I thought that all power supplies deliver current......?
A standard power supply is voltage regulated; that is, a sample of the output voltage is placed into an error amplifier, and compared to a fixed reference. The error amp determines if the voltage needs to increase or decrease, and will control the regulating device (tube, xistor) accordingly.A current source is essentially the same, except that a sample of the output current is placed into the error amp (this is typically done by dropping the current across a stable resistor to obtain a proportional voltage).
End result is that with a varying load, a voltage source will keep the voltage across the load constant (and current will vary), and a current source will keep the current through the load constant (and voltage will vary).
There are various theories about which is preferred for filaments, but essentially the power supply topology determines if the filament is receiving constant voltage or current.
Does this mean that one have to choose voltage or current regulated,or is it possible to feed the circuit with both ?
So this power supply showing for the Karna ; http://www.nutshellhifi.com/Karna.gif ,is voltage regulated only?
You can only have one or the other. You could have a current LIMITED voltage regulator, but it's still voltage regulated. If your current output (which will vary in a VR supply) goes too high past a design spec, the output will drop, effectively limiting the current output.The Karna design uses shunt voltage regulation for the B+ driver stages, but does not regulate the filaments. It basically is a voltage supply, with regulation determined by the 120VAC of your house power. If your house power drops to 115V, all filament supplies will drop by the same percentage. So while it IS a voltage supply, it is not specifically regulated.
Technically, it has pretty good load regulation, but no line regulation. That is, as the load varies, the voltage will be fairly constant. As the line (house power) varies, the voltage will change.
FWIW, I am currently building a Raven preamp, and am debating between an Amity or Karna design. I can say this much, as a licensed PE with good knowledge in both power and electronic theory, the Karna is a VERY daunting design. It may look easy and simple on paper, but the actual build and attention to subtle grounding is critical. If you are having some of the questions you are posing, I would kindly and respectfully steer you away from building it. At a minimum, try a "tiny" Raven design first, to see how successful you are.
I will consider the build of Amity/Karna,but as you said it also look managable from looking at schematics.I just figured since it has been around for a while I could get help if I ran into problems,but I will now consider not building it.
Maybe a Raven,yes.
> Does this mean that one have to choose voltage or current regulatedThe vast majority of regulated filament supplies are voltage (not current) regulated. One good reason for this is that the filament supply usually feeds a number of tubes in parallel. With a current source, removing a tube (or having a filament open unexpectedly) will cause the supply to increase the voltage to all the other tubes. So, safe operation requires either a crowbar across the output of the current regulator or a separate current regulator for each tube. On the other hand, the downside to voltage regulators (and simple filament transformers) is the inrush current when the tube is cold. This can be minimized if steps are taken during the design of the regulator to provide a slower start.
One solution to supplying two tubes - e.g. a diff pair - with one current source is to wire them in series. So if you remove one tube you break the circuit.
> ...wire them in series.Yes, that's a good option, although it does make it more difficult to know which tube of the pair has failed. I have to say, my preference in all this is a voltage regulator (voltage source) with a current limiter, not merely a simple current regulator. I believe tubes are spec'd and designed for a specific filament voltage, and that the filament current listed for most is only an approximation provided for use in determining supply requirements. Regulating the tube to that current is unlikely to be what the manufacturer intended.
my preference in all this is a voltage regulator (voltage source) with a current limiter, not merely a simple current regulator. I believe tubes are spec'd and designed for a specific filament voltage, and that the filament current listed for most is only an approximation provided for use in determining supply requirements. Regulating the tube to that current is unlikely to be what the manufacturer intended.I used to think that, I even wrote an article in AudioEXpress on the topic.
After adding series chokes to my battery supplied filaments I'm thinking the current reg has benefits above and beyond lighting the things correctly. It looks as though extra impedance in the supply line is beneficial - whether it blocks hash getting in or out I can't say, but it seems to do something.
BTW you can get around the issue with current v voltage by making the current reg adjustable and setting it so that the voltage drop across the filament is correct.
I agree with those who say that the high impedance keeps the audio signal out of the power supply. The last thing i want is a good portion of my audio signal finding its way to ground though the filament supply.How did you size your chokes for your battery supply? I pretty much size it so the Z at 20hz matches the filament resistance and see what that looks like.
For the 71As I used a pair of existing chokes which were about 1H and had about the right DCR to drop nominal 6.3V to 5V. I added a common mode toroidal which tops up the DCR.For the 211s I bought some big transformers off the shelf, unstacked it, unwound the primary and added a new winding. The winding roughly matches the DCR of the existing secondary to give me almost 0.8 ohms as required to drop nominal 12.6 to 10V with the 3.25A draw of the 211 filament. I will add an air gap with paper between the Es and Is and put it on the DCR bridge to see what I get and use the same trick with the common mode toroidals as above.
I have only just sorted the recharging for the 211 batteries so they haven't been installed yet. I'm using laptop power supplies (15V) and a silicon bridge rectifier to achieve 13.8V, the laptop supplies are current limited at 6A so this should work a treat for the 65 Ah batteries.
I'm curious, being as you're using DC on the filaments, why aren't you using SS devices for isolation? This seems like a very inconvenient application for chokes given the frequencies and currents involved. I should probably add that I'm on the outside of the current rage for SS CCSs, but this particular use would seem much less likely to color the sound. The impedance ratio of desired to undesired signal paths would be extremely high with a SS CCS.
The original circuits used fairly high spec SS devices (LT108X series regs). With the 71As I moved from there to series / shunt regulation using discrete devices, from there to SLA batteries and from there to SLA batteries plus chokes. I felt that each step was a worthwhile improvement. With the 211s I'm in the process of jumping straight from first to last.I tried SS current reg but didn't like it, YMMV etc etc.
I tried SS current reg but didn't like itYou probably have some theory about the reason why. No?
I never tried batteries, probably should give them a go.
I have compared a 6SN7 Aikido breadboard to an M10 and thought that the Aikido was much better. There is something really magic with that circuit. But it suffers from NIH (not invented here) syndrome.
Seriously?
Can you tell a little bit more about "sound" and what was better soundwise ?
Was it Audio Note UK or Kondo?
The pre was the UK one.This was some time ago and the breadborsd did have some hum. The Aikido was just was more natural and real sounding.
Dear 01A,Just out of interest, where did this comparison take place, there are no M10Line made by us in New Zealand.
Hi Peter,
The point of the matter is that one can DIY a product that is superiour to the best of the commercial stuff out there for ones own use. This is because as in cooking you can make it to your taste and you have a much larger selection of componants to choose from.Odd ball NOS or secondhand components are options.
There well be no M10L sold here. There are a lot of secondhand imports into the country. Anyway this not the point, as I said. The owner told me it was the top AN and I believed him. Again this is not a audiofool pissing site but a DIY site. Lets keep it that way.
All the best for your bussiness Peter.
Dear 01A,The owner would be John White and the pre-amplifier in question would have been the old power supply version of the M8Line which is 4 or more years old, not the M10Line, of which there are none in New Zealand, new or secondhand, (I know where every single unit sold is, and not one has ever been on the market second hand) just so you know.
Your comment about making DIY products that are superior to anything (even the very best) made by any commercial enterprise is interesting, because it assumes a number of things which are not as simple as they may look, because unlike in cooking, where you have a fairly well based set of recipies and rules for how ingredients combine, audio is a somewhat different kettle of fish and the complexities of combining different circuits with suitable valves and power supplies and then voicing the end result with parts which have a complimentary character is no small job.
In fact I would suggest that it is more than a full time job and takes very considerable expertise in not just circuit topology, power supply and transformer design, but also in the material sciences, not a cheap hobby overall if you are to do what you claim is possible.
I think I can justifiably claim to have the largest available selection of quality parts and materials at my disposal and I can tell you that no hobbyist anywhere could afford even a small percentage of the stock needed to make a single M10Line let alone have the necessary knowledge to create the maths that made the totally unique and innovative power supply possible (we have been awarded two patents on this power supply sofar, with more to come), so whilst I totally agree with you that as a knowledgeable hobbyist one can make some very decent sounding kit making something that is "the best" is not within reach.
I have the greatest respect for the DIY community and wish it well, but promoting the idea that you can voice your way past certain levels of quality is to delude yourself and whilst that is certainly in the ethos of the age we live in, I object to it in principle.
Sincerely,
Peter Qvortrup
That's quite a claim Peter. There is no such thing as a perfect device. And so, each design has to be tuned or should I say can be tuned to a certain type of sound with the ingredients. This can be done with any circuit. Some very simple circuits can be tuned to quite a high degree of fidelity. Simple looking circuits on paper may not be the easiest for the little guys to navigate (little guys being electrons).So you have your audio circuit and power supply design and you throw the best parts at it to make it the best thing you can make. Note the qualifiers in that this is "your circuit" so no better or worse than anyone elses who has put in similar groundwork and "your best parts" which are the things you think sound best in your circuit. That only qualifies things for your taste. If that isn't to someone elses taste, then your best isn't the best for someone else.
You therefore cannot claim that your product cannot be bested by someone else's design. Some people hereabouts may have been developing their design for far longer than you. But because they are a DIYer, you claim they cannot achieve what you do. Are you sure you are saying that?
Dear Stephen,If you read the Audio Hell article on our web site you will see that we actually describe what we strive for in our search for the best sound, it is our mission statement if you like, to me this is not a matter of personal taste, your choice of music is, not the way it should come off the software.
It is therefore one thing to be tuning a design or circuit, but unless one has a philosophical framework with which to judge whether one is moving forward or not, it is more likely that one would move around in a circle, but regardless of that, what I am taking about is far more fundamental that superficially "tweaking" a circuit (any circuit) to suit whatever system it happens to be used in.
To expand the envelope one needs fundamental research and the one thing about fundamental research is that it takes time and therefore money and even the most dedicated hobbyist no matter how long he/she has been playing with this hobby is unlikely to have the time, let alone the money to come anywhere near being able to investigate for example say; permeable materials, let me give you some background to this one subject.
Take the design of an ideal moving coil or input transformer for example, the standard type 18Lams while good are not ideal if one is seeking the lowest possible loss, best bandwidth and therefore best magnetic coupling between core and windings, so you design a core shape which has a different shape to achieve this, but to make it you need to buy 50 kilograms of 0.1 mm thick 84% nickel material and pay £ 10,000.00 or so for a tool to stamp it into laminations of the shape required (off course AFTER you have had some lamination samples made by laser cutting to make sure the core shape actually does what the maths tell you), the lams are then heat treated to whatever process give the material the best and most linear low level behaviour (this itself may require several attempts to be certain the potential of the material is optimised), meantime you thave bought 10 kilograms (this is the minimum quantity most metal processors will deal with) of 4 - 6 different gauges of polyurethane coated silver wire, so you can make full function prototypes to test for sound, only then can you wind a couple of transformers.
Now multiply this scenario a few times, to make for example the basis for the new GAKU-ON amplifiers, whose fully transformer coupled ultra simple circuit requires 3 different transformers (input with step up, driver and output) all of which have to be matched to each other to ensure matching behaviour, which requires us to make as many as 20 of each transformer to make one pair of amplifiers.
Are you seriously telling me that this is within reach of any DIY'er??
Your expression "similar ground work" would apply here, because THERE is NO similarity between changing a few parts in a simple circuit and what I am talking about here, is there?
Now take the above, expand the concept and apply it to making capacitors for example, and you can add further layers of work and cost.
So whilst you are quite right to state that there is no such thing as a perfect device (although some tubes do come close), and that some simple circuits may not sound as good as others, what governs seeking absolutes resides on a different level.
Like I said in my response to 01A, there are great things that can be done by building and modifying your system yourself and in many cases what you can make is both better and cheaper than many offerings available in finished form, I wholly support this notion, which is why I make all but our very most specialised parts available to anyone who want to pay for them, but one needs to understand that there are realms which cannot be reached this way.
Since you are in the UK, drop by anytime you are near Hove.
Sincerely,
Peter Qvortrup
Thanks for the comprehensive reply. I have in the past read the audio hell article and it is, for the most part, the way I audition and develop my own gear. However my point may have been slightly lost. Yours has been stated clearer. I don't doubt you think the way of your development to be the best and beyond a general hobbyist and for the given example, that probably is true. Where we part is the absoluteness of your statement that your way is "the best" way and that therefore a hobbyist doesn't have access to say ... a transformer winder with the same passion for his magnetics as you do. Might not be the exact same recipe but another, that has been through just as rigorous development as yours.All your development means is that your item meets the math (and I suppose audio criteria) you set out. As we all know, anything you make is a compromise. That's life. You might be taking a low compromise route but it is there. It has to be. you are developing a SET circuit. That doesn't mean someone else can't have their own goal and reach it in a different way. Their goal might have a higher bar :-)
What you seem to be saying is something very similar to what say Audio Consulting say in their mantra. If you think you have the ultimate solution, good for you but I find it difficult to accept you have beyond anything anyone else can do. Now the average hobbyist, fair enough but there are some pretty extreme people out there.
As you can see, I have a real issue with absolute statements because in this game, there are none.
Thanks for the invite. Was down that way seeing my dentist last weekend :-)
cheers,
Stephen
Dear Stephen,It really is not a matter of what I think, the way I approach the subject of music reproduction is that the job of the equipment is to reproduce what is embedded in the software with the least possible interference, for good or bad what is on the software is "absolute" as far as I am concerned and if we want to access as much of the message that it contains, then we have no choice but to design equipment which extracts this information properly and that means finding the relevant technologies to do so.
The sound of a given recording is therefore not a matter of "taste" (you may not even like the music), it is a matter of getting to the core of the sound of the recording, that, and only that, is what we strive for, because at the end of the day the equipment that achieves this is the most accurate and so far I have not been disappointed, as each step closer to this goal has exposed unexpected improvements in most recordings.
I agree with you that at the end of the day, it is an unachievable goal, but it has to be the end goal regardless, because what else is there to aim your efforts at??
Unlike mountain climbing, where there are, or at least may be, several routes to the top, in audio there is only one road to the top in each discipline and the quest is to find which one and then combine it with the same in each part of the system, take speaker magnet systems for example,
At the bottom of the "sound pile" are,
Cheap ferrites, then
Better ferrites, then
Neodymium or samarium cobalt, then
AlNiCo and last but not least,
Field Coils with copper windings, only improved upon by,
Field coils with silver wireTo prove the validity in the above, it can be shown to repeat itself with moving coil cartridges' magnet systems, where a field coil wound with silver wire is clearly superior to any other magnet system, provided it is fed by a clean source of DC.
Similar hierarchies exists in every other area of audio, what is lacking is a general understanding of why this is so and a general agreement that this is so and then a way of proving it technically (in most cases it is actually quite easy to hear), so whilst everything is a compromise, there are compromises and then there are "compromises" where a lack of understanding hampers the end result or where the emphasis has been weighted towards cost, either to allow for low price or a great advertising budget, both of which are effective sales tools to the uninitiated and especially the illinformed and selfserving press!
If we are talking absolutes, then cost is not a consideration and cost is after all the final bar to achieving this illusive goal, is it not.
I don't think this end goal is beyond anyone with the intellect, determination, commitment, time and money but especially the openmindedness required to disregard conventions for long enough to realise that travelling uncharted roads can yield great and unexpected results, although it will always remain the domain of the few.
I realise fully that for most people to deal with this level of uncompromising zeal is at best uncomfortable, but without it little real progress is ever made.
Sincerely,
Peter Qvortrup
Hi Peter,
If cost is one thing that stops people achieving the absolute in your terms how does John Britten DIY a world beating motor cycle in his garage in his spare time with only basic tools? He manufactured every part of the bike, winning the world 500cc. The other manufactures have mulitimillon dollar budgets and hundreds of staff to make the best in the world.This is something that is measurable.
There are many ways to skin a cat. Both Gordon Rankin and Allen Wright , as some say ,make the best amplifiers in the world. You will not find them troubled with interstage transformers.
Lastly does a Rolex watch tell the time better than a Timex?
Does a Mont Blonc pen write better than a Bic?
A lot of manufactures are in bussiness making the best.
Reminds me that I must buy my wife a $10,000 Louis Vitton hand bag I am sure that it will hold her purse better.
All the best.
Dear 01A,Reading up on John Britten on his own web site, I believe he had a little help in his venture from people who were knowledgeable in areas where he was not, having said that he is a good example of how commitment and dedication can create greatness.
But being mainly mechanical and also dependent as much on the quality of the rider as on the design, motorbikes are not audio, so there are few relevant similarities.
I find it interesting that you bring up watches, one of the arguments that has traditionally been used by the very people who promote transistor amplifiers and digital technology is the fact that a digital watch is a far more accurate time keeper than any mechanical watch, and digital technology is therefore superior overall, sort of a strange argument to use for someone who himself believe in and DIY's the opposing technologies.
As you said it yourself, "Again this is not a audiofool pissing site but a DIY site", so I shall refrain from commenting on the rest of your post.
Sincerely,
Peter Qvortrup
Thanks,
that sounds pretty unbelivable,but I try to always keep my mind and ears open,so nothing would be better to me than if the Aikido really sound more natural and real! :-) I like that you use those exact words too,because that give much more sense to me than talking about any "highend-words" ;-)Do you have a schematic of the version you've built?
And how are your power supply constructed?I have looked some at this schematics ; http://www.tubecad.com/2004/blog0011.htm
It shocked me that it sounded so good.I used the schematic in the blog about the distortion mesurments. The version that Broskie was going to build. Unbelivably low distortion. My power supply was pretty dam good.Choke input all film foil caps etc.
This is starting to tempt me very much :-)
I'm not the right person to discuss electronics and schematics,but from looking at the schematic I would have guessed that this design would impart much more time and phase artifacts to the music-signal than for example a simple ultrapath design..........
I made the Ultrapath a few years ago - and needless to say - it wasn't the greatest I've ever heard.... I used some nice 12J5s, outboard regulated supply,etc and I got the hum levels really low... but it got beat out by my next build.if I would do it again - I would have picked some different tubes, power supply, volume control, etc
(also - beware of my webpage - lots of pop-ups with the 50megs site!)
And your next build was the EF86 linestage ?
Interesting stuff!
Guess the first question is... Why did you get rid of all of those ver good preamps?And keep the Eastern Electric? Do you like it better than the ones you got rid of?
Please tell us your thoughts on the EAR, Tram. and AN M-3, it will help us to fully understand your question.
Well, what I would like to know is if anyone have compared any of the above mentioned to really good finsihed products,and also if someone have compared a Raven to lets say a version of the Akido....My goal has all along been to be able to build things more and more from schematics and with time own ideas,so all the mentioned preamps was a kind of learning process for me.They do all sound good and different,but I sold the once that gave me the most money ! :-) ,to start on new projects.And when I see Lynn Olson mention the Karna along champs like the Ongaku(allthough I never heard it),I guess I can expect some very good quality from the Raven as well.Maybe not Audio Note M10 territory,but maybe better than the M3 kit,which I liked the most of all the preamps I've had.
> we have 230 Volt and 50Hertz net specsWhy not be safe and build a separate power supply chassis? This is DIY, after all. :)
BTW,since I'm from Norway we have 230 Volt and 50Hertz net specs. Do you think that can give me any noise/hum problems from constructions like Raven which is voiced with 120 and 60(?)Hz ?
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