Hi All,
I'm going to buy Welborne Labs DRD-300B for my first tube kit... but then I'd like to build something on my own. I've got all the recommend books, slowly going through them again.
I'd like recommendations for topologies that have as few components as possible in the signal path. Reason being, I figure I can understand better what each component is doing when they're more discrete... plus I'd like to mess around with the sound of different components (brands of resistors/caps for example).
Also, what's the recommendations for modeling software for these 'reduced component' amps?
I'm going to buy Welborne Labs DRD-300B for my first tube kit... but then I'd like to build something on my own. I've got all the recommend books, slowly going through them again.
I'd like recommendations for topologies that have as few components as possible in the signal path. Reason being, I figure I can understand better what each component is doing when they're more discrete... plus I'd like to mess around with the sound of different components (brands of resistors/caps for example).
Also, what's the recommendations for modeling software for these 'reduced component' amps?
this is very simple and does fred does a great job of explaining what each part does. i built mine in stereo, it just takes a few mods to the power supply.
http://www.dogstar.dantimax.dk/tubestuf/miniblok.htm
http://www.dogstar.dantimax.dk/tubestuf/miniblok.htm
Would you classify this as a Learning Amp or a Live-With forever amp?
Hiya,
Notice that this is a 1-watt amplifier, so would be below what the DRD-300B puts out... but could be a pretty decent Computer Amp for some really-nearfield listening.
But, would you classify this as just a learning amplifier, or something that I could be happy with for a long time?
The reading is Great!
This definitely helps, but I don't know if I'll build.
That's another problem I have... this puts out a watt... the drd-45 puts out ~2 watts, but costs x10 what this 13EM7 amp costs; would this tube/amp allow me to hear the difference between using generic caps vs. say Blackgate caps vs. Jupiter Caps?
Hiya,
Notice that this is a 1-watt amplifier, so would be below what the DRD-300B puts out... but could be a pretty decent Computer Amp for some really-nearfield listening.
But, would you classify this as just a learning amplifier, or something that I could be happy with for a long time?
The reading is Great!
This definitely helps, but I don't know if I'll build.That's another problem I have... this puts out a watt... the drd-45 puts out ~2 watts, but costs x10 what this 13EM7 amp costs; would this tube/amp allow me to hear the difference between using generic caps vs. say Blackgate caps vs. Jupiter Caps?
The latest AudioExpress had this circuit in it.
It's about as simple as it gets.
An externally hosted image should be here but it was not working when we last tested it.
It's about as simple as it gets.
Oborous,
(isn't that a worm???)
I don't understand why you don't build the DRD 300B. Can you solder? If not, are you willing to learn? (I think the answer to that must be "yes" as you are asking about scratch-building a second amp)
It is not my intent to cost Ron a good sale, but you seem ripe for the project. The schematic is on the Electraprint website. The parts count is very low and though it is a bit difficult to understand at first, I can walk you through it if you wished.
You can get all the signal path transforners from Jack at Electraprint and can use Hammond PSU iron from Antique Electronics. Parts count is very low and if you use a larger chassis than I did, it is ;quite easy to build. Mine worked as promised the first time I threw the power and sby switches.
As for the sound, I think it is superb as do all my friends who have heard it. Dynamics are startling and detail is incredible. I can heaar no "tube euphony" though it is very warm and engaging. It is merciless with poor recordings, showing up the mess the engineer or production folks made of it, although bad ones still exhibit the qualities I mention above.
Well, you might not need the above "road test" since you've already schosen that design to buy. If you choose to build it, I'll help and I'll bet others on this forum will, as well.
http://www.electra-print.com/drd6an4.html
Cheers/The Fader
(isn't that a worm???)
I don't understand why you don't build the DRD 300B. Can you solder? If not, are you willing to learn? (I think the answer to that must be "yes" as you are asking about scratch-building a second amp)
It is not my intent to cost Ron a good sale, but you seem ripe for the project. The schematic is on the Electraprint website. The parts count is very low and though it is a bit difficult to understand at first, I can walk you through it if you wished.
You can get all the signal path transforners from Jack at Electraprint and can use Hammond PSU iron from Antique Electronics. Parts count is very low and if you use a larger chassis than I did, it is ;quite easy to build. Mine worked as promised the first time I threw the power and sby switches.
As for the sound, I think it is superb as do all my friends who have heard it. Dynamics are startling and detail is incredible. I can heaar no "tube euphony" though it is very warm and engaging. It is merciless with poor recordings, showing up the mess the engineer or production folks made of it, although bad ones still exhibit the qualities I mention above.
Well, you might not need the above "road test" since you've already schosen that design to buy. If you choose to build it, I'll help and I'll bet others on this forum will, as well.
http://www.electra-print.com/drd6an4.html
Cheers/The Fader
Brett said:
Hmm... Probably one of those things I should have written in my original message. Basically I'm looking for various topologies for me to research and then try a couple of them. I'm looking more for Keep & Use amp, rather than a learning amp. I'm not ready to go into Horns, I prefer a larger sweet spot; so I'd say ~8+ watts should keep me happy. The flea power amps would get relegated to computer speaker amps, if they were a Keeper amp.
I really want to build an elegant, simple amp based around a 211/vt4-c/845/gm-70 (Yes, I realize that Electra-print is kind and has a nice gm-70 booster amp to run off of a drd-300b... but I don't understand why they'd decide to drop it into a 6 ohm output, compared to a 4 or 8... hence I realized I need to learn more)
Within the scope of this project (Learning Curve), cost is no object.
I always figure I'll come up with something else to use quality parts for; but I'm trying to learn the difference 'sounds' between parts. I may be making a wrong assumption here... that fewer parts will allow the individual component characteristics to show through, so I can evaluate brands better.
I consider my audio learning curve to be similar to scotch, at first I couldn't differentiate the subtle nuances of scotch, but now I can; plus I'm not worried about getting caught up in 'it costs more, so it must be better', many times the cheapest is actually the best.
John Fader said:
I can sling solder, confident in following an established plan, with support network, but that's still someone elses work.
I am going to build the DRD-300b... it's such a simple schematic, beautiful implementation, all the reviews of people that listen to similar music to me really enjoy it. Plus, I did a 'individual purchase' comparision to the price Ron offers; The price is slightly higher for me to individually buy the components, compared to going through Ron... plus I get the advantage of the support network.
The problem is... I like research, I'm trying to learn... At this time, I can't figure out if I wanted to tweak, say the 200 ohm resistor before the 300b tube in the DRD, should I go higher or lower, will that cause oscilations to go out of control, or will it make no difference, or is this resistor there as a safety measure. I want to build the DRD's, have them for primary listening, and then use them as a base line; I know my Audio Memory is short (even in comparision to the average), so more of a great set of amps for compare and contrast my projects to.
I appriciate the offer of help, that's one thing that drew me to this hobby, the culture and the support; but ultimately it's going to be my arm in the guts of the amp with 400-1,200V of juice... I need to increase my comfort level by knowing what's going on; so I figure I need to design my own circut based off of an established circut, and post it for peer review.
Well you're listening to the wrong horns. Mine have quite a large sweet spotOborous said:
For a really well thought out 211, the late John Camille did one back in Sound Practices.
As for the 6 ohm GM70, well that's pretty logical as the vast majority of modern speakers would have an average impedance of 6 ohms, no matter what they're nominal rating is. Tube are quite tolerate of the load and it usually doesn't make that much difference sonically to move from 8 to 6 ohms
Buy quality iron; it lasts forever and can be onsold for little loss if you change your mind.Within the scope of this project (Learning Curve), cost is no object.
I always figure I'll come up with something else to use quality parts for; but I'm trying to learn the difference 'sounds' between parts. I may be making a wrong assumption here... that fewer parts will allow the individual component characteristics to show through, so I can evaluate brands better.
For passives, buy lots of cheap parts and use these to build the circuit with in the first instance. Then change them out for "better" parts. Some things like Mills resistors I just use for all higher power signal paths stuff because I haven't found anything better, they're well made, decently priced and tough.
Quite often reasonably priced parts are the best, if for no other reason than they're cheaper. Beware of self delusion.
LEARN SOME HIGH VOLTAGE SAFETY BEFORE YOU START. Sorry to shout, but I've seen too many stupid mistakes hurt people, who often should know better, and 1200V can kill you real quick. For instance, when working on live HV equiptment, ie anything above 100V, keep one hand in your back pocket, use good insulated clips on your meters/CRO leads etc, and think about nd plan what you're going to do before you power it up, eg, are you planning on making a series of measurements relative to ground? Well hook up the ground before power up, rather than reaching across live gear ro do it. Have an easily accessible kill switch, clear thought out work area etc. It's all common sense.
Brett said:
Hmm... will have to hunt down that 211 schema.
Quality Iron - That's what I hear, it seems to be the part that most people skip, then go for boutique resistors or caps. I really want to try cobalt OPT's, once I accepted that fact, reistors/caps become much more immaterial to the total project cost.
'Cheap Parts' - One thing I want to try is that resistor baking... forcing aging, and buy 100 of the required value, then matching as much as I can, see if having every component matched makes a difference. Really, once I purchase the Tranny's and Tubes, unless I go nuts with Audio Note Silver (I almost feel like I should put a TM here...) Capacitors, I can't see the price fluctuating that much.
High Voltage Safety - Definitely! I don't think too much safety ever hurt anyone. I'm going to install a GFCI breaker for my work bench, buy a variac (to slowly raise the power to 120v), I'm thinking of one of those sewing machine foot peddles for a kill switch. Work bench is purposefully narrow so I don't put things behind the project. No stool or chair, standing only. Work area is pretty open, so if I scream other people in the house will hear... I think those tiny closet work areas in the basement are dangerous because you can't call for help.
Maybe a simpler question
Pardon my ignorance for this, but...
Basically, OPT's will be the same for a given tube, correct?
I mean, say I really want to do a 300b based amp, unless I'm doing something strange and 'overdriving' the tube, because the output will be the same no matter the topology...
So, really, I could order up an extra OPT & PSU tranny for my (future) DRD-300b's, use it as my test transformers, no matter the topology, I could require some interstage transformers, or a second PSU tranny for what kind of other driving stages I'm using in the amp.
Or am I missing something here?
Pardon my ignorance for this, but...
Basically, OPT's will be the same for a given tube, correct?
I mean, say I really want to do a 300b based amp, unless I'm doing something strange and 'overdriving' the tube, because the output will be the same no matter the topology...
So, really, I could order up an extra OPT & PSU tranny for my (future) DRD-300b's, use it as my test transformers, no matter the topology, I could require some interstage transformers, or a second PSU tranny for what kind of other driving stages I'm using in the amp.
Or am I missing something here?
Hi Oborous,
Regarding component quality, everything makes a difference down to the type of dielectric used on magnet wire. In my experience of these differences, I've never replaced a component that functions truer-to-ideal with one functioning at a lesser-than-ideal level and said, "Wow, I like that change." You basically get what you pay for on a declining economy of scale basis. Those zillion dollar teflon capacitors actually *do* give better performance.
My two cents.
Regarding component quality, everything makes a difference down to the type of dielectric used on magnet wire. In my experience of these differences, I've never replaced a component that functions truer-to-ideal with one functioning at a lesser-than-ideal level and said, "Wow, I like that change." You basically get what you pay for on a declining economy of scale basis. Those zillion dollar teflon capacitors actually *do* give better performance.
My two cents.
oroborous,
pardon the directness, but I think you're making too much of it.
Get some stuff and build something and leave alone all this theorizing, which will get you very little gain.
I'd suggest you look at the Darling amp as you're learning about circuits. For a mini-watt amp, it is difficult to better. There is lots of comment on the Darling website to help you understand what's going on in the various modifications of the design.
Cheers/Fader
who is just trying to give good advice
pardon the directness, but I think you're making too much of it.
Get some stuff and build something and leave alone all this theorizing, which will get you very little gain.
I'd suggest you look at the Darling amp as you're learning about circuits. For a mini-watt amp, it is difficult to better. There is lots of comment on the Darling website to help you understand what's going on in the various modifications of the design.
Cheers/Fader
who is just trying to give good advice
Re: Maybe a simpler question
The other thing to consider in a SET amp is that the transformers have a gap in them to allow DC. Differnt tube have differnt standing/quiescent/DC curent requirements. EG a 300B likes to work at around 70mA so getting a transformer gapped for something near this will work fine with the 300B and other tubes that like a similar standing current. However some tubes like a 6C33 like 200mA so the 300B transformer would saturate. My example is simplified and desn't take into account the primary Z too.
Of course PP amps require different OPTs and generally won't work in the other circuit.
Sort of. Triodes are very tolerant of varying loads, so the primary impedance of a transformer can vary over a range of values and still be fine. Go get the WE 300B datasheet from their site and look at the power vs load graphs at the end. Also on the site are 2H and 3H distortion graphs vs primary impedance.Oborous said:
The other thing to consider in a SET amp is that the transformers have a gap in them to allow DC. Differnt tube have differnt standing/quiescent/DC curent requirements. EG a 300B likes to work at around 70mA so getting a transformer gapped for something near this will work fine with the 300B and other tubes that like a similar standing current. However some tubes like a 6C33 like 200mA so the 300B transformer would saturate. My example is simplified and desn't take into account the primary Z too.
Of course PP amps require different OPTs and generally won't work in the other circuit.
Yes.!!John Fader said:
Adding another piece to the OPT thread, you can use (with a given tube) an OPT with a higher primary Z with benefit, but don't go lower. as Z[ri goes down(which is a *heavier* load, in opposition to what people generally say , power goes up but so does distortion. The opposite is tru as well, a higher Zpir (lighter load) decreases distortion and power.
F'rinstance, my 300B DRD uses a 4K Ohm OPT.It gives 9W @3% distortion. With a recommended 3K Zpri, you'd get maybe 12W but the distortion would be 5% at that power. BTW, these figures are higher than the WE book shows, and that book is overly optomistic on both power and distortion I can't explain it, but everyone who builds one of these things reports this phenomenon. Anyway, back to the subject; the difference between 3% and 5% distortion is a *lot* but the difference between 9W and 12 is only approx 1 dB. Good tradeoff IMHO. So, don't be afraid to ask (Jack for an OPT with a Zpri around 35% higher than recommended. The operating point will likely have to be different, but it is not difficult to jack the current around a bit to find a sweet spot.
Hope this isn't too obscure (though it over simplified) and helps a bit.
Build something!!!
Cheers/Fader
, power goes up but so does distortion. The opposite is tru as well, a higher Zpir (lighter load) decreases distortion and power.F'rinstance, my 300B DRD uses a 4K Ohm OPT.It gives 9W @3% distortion. With a recommended 3K Zpri, you'd get maybe 12W but the distortion would be 5% at that power. BTW, these figures are higher than the WE book shows, and that book is overly optomistic on both power and distortion
I can't explain it, but everyone who builds one of these things reports this phenomenon. Anyway, back to the subject; the difference between 3% and 5% distortion is a *lot* but the difference between 9W and 12 is only approx 1 dB. Good tradeoff IMHO. So, don't be afraid to ask (Jack for an OPT with a Zpri around 35% higher than recommended. The operating point will likely have to be different, but it is not difficult to jack the current around a bit to find a sweet spot.Hope this isn't too obscure (though it over simplified) and helps a bit.
Build something!!!
Cheers/Fader
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