Selecting Capacitor(s) and Resistor(s)

[OldHector]

Can't remember who said it, but there are the things one knows, the things that one does not know, and then the rest, the unknown unknowns.

Experience is invaluable to get you on the same page as the people offering you advice, so the unknown unknowns start to disappear.

BUT ... you are set on creating two monoblocks based on a non-trivial design, do it point-to-point AND build your speakers all at the same time. I do not believe that is possible - there are two many risks of failure considering all of those unknown unknowns.

You would really make your life easiest by building a well known and straightforward design on a PCB and getting it to work. There is no better contender than the Tubelab SPP, unless you want to buy a more expensive kit of parts. The support I have had here has been fantastic, and has helped me progress from your experience level to where I am today - more in awe of skills of the designers of great amps than ever.

Once you have built the SPP you have all the expensive components to build a pair of monoblocks, bar a choke and a power transformer. Don't try and eat the elephant in one sitting.

 

[HalFoster]

'Stand on a thick rubber mat' is serious. 'Keep your left hand in your back pocket' is serious. What often results in death is current flowing through the left arm, down through the heart area and through a leg or legs to ground. Cement floors contain water and are considered conductive for this risk factor. Arcing through the soles of shoes has resulted in deaths and or severe injuries.

Other than that, plan out your test electrical measurement physical movements, and practice those moves you will be making while the power is off and the circuit is discharged. A loose scope or DVM ground lead falling off and hitting a high voltage node can be extremely dangerous.

DVM probes and meters are good up to about 600v. Peak voltages in tube circuits such as pulsating voltages before rectifiers can often go above that value. A high voltage DVM probe is a wise investment for working on HV circuitry. https://www.amazon.com/high-voltage-probe/s?k=high+voltage+probe Make sure to keep track of where the ground lead is and that it is secure at all times.

Capacitors can be discharged by shorting across their terminals. A screwdriver is sometimes used for that purpose (sometime referred to as a 'crowbar'). It may be wise to wrap some bare wire around the metal screwdriver shaft and secure the wire to a solid, reliable ground. Be very careful to note where the bare wire is at all times and that it doesn't touch anything it isn't supposed to.

Don't just listen to me either. Read up on the subject. Here is one page you might take a look at: https://robrobinette.com/Tube_Amp_Safety.htm

Regarding medications, sleep medications have been known to affect daytime behavior. Any med you take may have some risk factor. Read drug information for patients carefully to see if there are possible risk factors for driving or using heavy machinery. High voltage work may also be affected if driving and or use of machinery are known risk factors.

All very good advice. A very helpful tool is to take a 10R or so power resistor, attach alligator clips and insulate it all well; use to discharge capacitors prior to servicing.

 

[Adriel]

If you remove the gNFB there will be too much gain.

How do you know too much gain? How then are PPs with this too much gain sounding better than with less gain? Not arguing, trying to wrap my mind around what seems illogical, hopefully not offensive doing so.


Why do pre amplifiers exist? Is it not to increase the gain of the amplifier? Meaning, without pre amplification the amplifier's gain be reduced? As I understand, EL84s can sometimes not benefit from a pre amplification and had planned to try it without to make a determination on the necessity.

Some of which can be lost by triode connecting the tubes.

What does this mean?

Maybe the better question to ask is whether this is a triode or pentode PP.

A 2 resistor divider on the input can also work.

Okay.

 

[Adriel]

Adriel, you may appreciate this meta view of learning:

I appreciate you sharing, thank you. 🙂

For electronics, we learn in a somewhat different direction. Rather than bore down from observations towards a deeper reality, we begin with a rudimentary but absolutely necessary knowledge of some fundamentals (Ohm's Law, resistance, capacitance, inductance, vacuum valve and semi-con operation, etc.) and work upwards towards modelling. Doesn't have to mean modelling in a computer simulation, and in fact it shouldn't until mental models are already in place. But! attempts to shortcut the learning curve by moving directly into detailed design decisions based on internet lore are fraught with peril.

Why do I come across as untrustworthy? I get this a lot from folks and I used to spend a lot of time and energy I don't have to convince them otherwise. I have more than once asked where I am deficient and been denied a response.

Additionally, how much knowledge do we need to build a simple amplifier? Do we need to know why we perceive the sky as colored blue to see the sky? To we need to know what causes us to perceive sound to hear sound?

The internet is full of Lore. Sometimes it's interesting, sometimes it's even correct, and sometimes it's valuable, but without the fundamentals it's impossible to tell which is who. I strongly recommend to folk wishing to actually learn, to ignore as much as possible internet Lore. Recommendations from trusted sources (diyAudio is probably as trustworthy as these things get, and even it isn't perfect) sometimes excepted. Still gotta flex and exercise to keep your BS detector front and center.

This is why I ask if my understanding is correct. One understanding is built on another. Take for example a members seeming back and forth. Either I must build an amplifier of no use and benefit other than knowledge or not, can't be both. If I must build more than one to be able to even build a satisfactory result, then I can't afford to build an amplifier; I don't have the $3.000USD plus for such an endeavor. I am permanently disabled and unable to be employed, so at this time, getting about $600USD a month. As I understood, because getting SSI, why my food stamps were terminated, so that is it for the dogs and I. Oh and I been asking around for odd jobs, maybe a little something in the summer (interior painting of a friend's rental), so not sitting here expecting mana to fall in my lap, still have to go out and pick it up.

Maybe this be be of some benefit to someone?

I am an INTJ personality, so I desire understanding and think in systems. For example, if the only hinderance is building the PP @oemcar recommended, the value was previously determined and should be able to be determined, though by whom is another question. If we are unable to determine this, then I see doing the BOM as a community service and build the Dyna or Tube Lab amplifier. Das sit alles.

Additionally, I tenacious and driven personality, though certainly not type A (type D IIRC, been a long time since looked into it). In I agree with John Lennon that there is no problems, only solutions, plus, that I generally don't take no as an absolute. For example, if the Audio Note clone can't be built now, doesn't mean on the wonderful day bio "mother" passes (she is in a lot of pain, going through a slow death) can't use some of my inheritance to acquire the ability to determine the resistance value of R16 or maybe purchase the real L1s.

I ask questions not to annoy or to argue (how us INTJs are usually understood), rather, to gain understanding, determine validity of the idea or system, and direction to proceed. For example, we have, due to the plethora of generosity, R16 is a crucial unknown to make known if the path to proceed down or the other option is the a different path.

 

[Adriel]

🤨 ??

What brand and model of output transformer did you use?

 

[Adriel]

Here is a very basic video which helps explain the importance of OPT specification and screen voltage:

.

Hope this helps someone. 🙂

 

[Markw4]

How do you know too much gain? How then are PPs with this too much gain sounding better than with less gain?

If designing an amplifier that is intended to use negative feedback, then it must be designed with more gain than if it were intended to operate without feedback. If using feedback then the feedback ends up controlling the effective gain of the amplifier. The extra gain in a feedback amplifier is used for what is called 'loop gain,' which is the gain around the feedback loop, which then ends up being used to reduce distortion. Its going to take some time to understand feedback. There is some math involved, although much of it is commonly reduced to the high school algebra level (although for a very good algebra student).

 

[Adriel]

Experience is invaluable to get you on the same page as the people offering you advice, so the unknown unknowns start to disappear.

So doing some research and coming close is not sufficient?

I will ask again, must one build more than one amplifier to achieve one satisfactory amplifier?

BUT ... you are set on creating two monoblocks based on a non-trivial design, do it point-to-point AND build your speakers all at the same time. I do not believe that is possible - there are two many risks of failure considering all of those unknown unknowns.

Is point to point harder? I would think easier as can see the color coded wire versus a thin trace. Schematics are easy to follow, I been working left to right. Trick is looking for the dots (meaning a connection) or arches (a wire going over another wire) so not connecting items that should not be connected.

Where did I say I was building speakers at the exact same time?

If think this because modeling, modeling doesn't mean building.

Additionally, as I said, I have 20 watt speakers and a 75 watt integrated. One bass driver now is rattling and if driven hard, smells really foul. I like to have a pair of small speakers for the work room, like the mid and highs of these Grundig speakers, so will hunt up replacement bass drivers. If even that is too much, I could stick to listening with just one speaker for a time.

What started this whole thing about building an amplifier is being told driving the BIBs with 75 watt amplifier be way too much, would not get the volume to a level for reasonable listening level of about 40dB.

You would really make your life easiest by building a well known and straightforward design on a PCB and getting it to work. There is no better contender than the Tubelab SPP, unless you want to buy a more expensive kit of parts. The support I have had here has been fantastic, and has helped me progress from your experience level to where I am today - more in awe of skills of the designers of great amps than ever.

Life isn't supposed to be easy, we are to toil until our last breath. The more toil, the greater our reward. Which tastes better, instant potatoes or real mashed potatoes?

The only unknown in the Audio Note clone is the relationship between R16 and the OPT. I am no hurry, figure give it a couple, few days and see if the OPT becomes known. If not, then proceed a different path.

 

[Adriel]

If designing an amplifier that is intended to use negative feedback, then it must be designed with more gain than if it were intended to operate without feedback. If using feedback then the feedback ends up controlling the effective gain of the amplifier. The extra gain in a feedback amplifier is used for what is called 'loop gain,' which is the gain around the feedback loop, which then ends up being used to reduce distortion.

What would happen if a 15kΩ resister was used?

25kΩ?

50kΩ

100kΩ?

Feedback still be supplied, with less and less risk of oscillation, correct?

Which be worse, oscillation or distortion?

I was of the understanding an oscilloscope could be used to find a satisfactory value for R16, wonder then how Audio Note and @oemcar not being able to use an oscilloscope found the value of 10kΩ and 12kΩ. 🤔

 

[Markw4]

Oscillation is bad in an amplifier. There is an old EE joke that says, "If you design an amplifier it will oscillate, if you design an oscillator it won't."

If you want to start understanding feedback in a simple way, particularly for what are called 'unity-gain stable' opamps then you might read this sort of thing:
http://www.learningaboutelectronics.com/Articles/Op-amp-gain-calculator.php#:~:text=This calculator calculates the gain of a noninverting op amp,= 1 + RF/RIN.

After that you could try taking a stab at the attached.

EDIT: A free book you can download - https://www.analog.com/en/education/education-library/op-amp-applications-handbook.html

 

[OldHector]

Is point to point harder? I would think easier as can see the color coded wire versus a thin trace. Schematics are easy to follow, I been working left to right. Trick is looking for the dots (meaning a connection) or arches (a wire going over another wire) so not connecting items that should not be connected.

Point to point is an order of magnitude harder unless you are following clear diagrams that show the placement of every component, and you have the right tags in the right places to keep lead dress reasonable, and have access to test points to evaluate the build. You have more chance of a fire and expensive damage when you first switch on with point to point.

This is a good tool to develop the layout. It is fun to create the parts with the real world sizes. orientate the tube bases and wire it altogether in the drawing tool.
DIYLC
Post your results here when you are done so they can be sanity checked before you do it for real.
Remember that all the peripherals have to be linked in somehow, and you will need to think of earthing and grounding, as well as fuses and basic safety considerations (e.g. earth lead to chassis).

 

[Adriel]

Point to point is an order of magnitude harder unless you are following clear diagrams that show the placement of every component, and you have the right tags in the right places to keep lead dress reasonable, and have access to test points to evaluate the build. You have more chance of a fire and expensive damage when you first switch on with point to point.

I appreciate informing me of the perils, thank you. 🙂

This is a good tool to develop the layout. It is fun to create the parts with the real world sizes. orientate the tube bases and wire it altogether in the drawing tool.
DIYLC

Apparently Java no longer longer works on a Macintosh, I put the correct password in and keeps asking me to put it in again. Trouble with running programs originally designed for Microsoft OS. Why I kept the desktop computer. Which is running Windows 7, second best OS, the best is XP which sadly no programs are compatible with. The keyboard and mouse for the desktop should be here sometime tomorrow, hopefully still works to use the USB to cellular as a hot spot, Microsoft OS hates wireless internet (asinine to design a computer requiring a third party adapter to function). If that is a go, then hopefully get some modeling done soon.

Post your results here when you are done so they can be sanity checked before you do it for real.

I will do this for any of the designs.

That reminds me, I forgot to look for a BOM for the Dynaco ST-35.

 

[Adriel]

Well, the Dynaco ST-35 is no longer an option, the OPTS are NLA. As has been clearly stated, without the OPT, the amplifier can't be built.

There is one kit supplier left, not sure what they are using for transformers, also the price is a bit steep for what I was hoping to get this done for: http://www.tubes4hifi.com/ST35.htm. Additionally, not sure of the kit quality, have to be investigated.

There is the also the concern some call a ST-35 an integrated amplifier and not a monoblock, I would desire to be certain it is a monoblock. However, that is now moot with parts not being available.

Though just hit me, maybe there is such a thing as integrated monoblocks? 🤔

Not sure when Steph of Skunkie Designs have the schematic done for the Tubelab PP. My concern waiting be it doesn't come.

I know of one or only two other EL84 monoblocks, both have been built by one person as I understand, so be even worse situation than already in.

 

[Markw4]

Integrated amplifiers include preamps and sometimes even DACs. Monoblock amplifiers are normally driven by a single stereo preamp. That's probably a good thing since then there is only one volume control to manage. Otherwise every time you wanted to adjust the volume level you might have to also fix L/R balance.

 

[Markw4]

BTW, tube amplifiers are not necessarily better sounding than solid state. Solid state, if properly implemented, can sound as good or better than tubes.

 

[kodabmx]

I started with point to point. It's like connect the dots and I find it nowhere as troublesome to build as Hector implies. To troubleshoot? Yup.
Here's a phono stage using 8 dual triodes I did point to point 5 years ago.

 

[Adriel]

Integrated amplifiers include preamps and sometimes even DACs.

I understand, thus why I was puzzled.

Monoblock amplifiers are normally driven by a single stereo preamp.

Does a monoblock have to have a pre amplifier? I have read some tube amplifiers not having a pre to drive them.

That's probably a good thing since then there is only one volume control to manage. Otherwise every time you wanted to adjust the volume level you might have to also fix L/R balance.

The Audio Note has one volume control, controlling both monoblocks, so the left-right balance is not affected.

Maybe this is why gain has been a concern, in that the understanding was there was no way to reduce the gain? 🤔

 

[Adriel]

BTW, tube amplifiers are not necessarily better sounding than solid state. Solid state, if properly implemented, can sound as good or better than tubes.

Tubes have less dampening though often better sounding miss and highs. There is a certain texture and personality to tubes which I prefer, though the SU-Z600 does have some personality and sounds nothing like the cold Class D I used to use. Plan was for the base to be handled by SS, by the way.

 

[oemcar]

😳 Oh dear. Well not sure when @oemcar and @huggygood adjusted the design

I didn't adjust the design- Rev F came from this thread:

https://www.diyaudio.com/community/threads/audio-note-kits-l1-build.198523/page-3#post-6278171

I mapped the ChiFi board from my original purchase and built this first design change... then built 2 others after that, with same mapping and new PCB. Changed PP design from 6BQ5's to 6GM5's... but thats another saga learned thru building and listening... NOT typing🙄

And, as I said before...

You gotta stop typing, and start soldering, It will open up so, so many...

 

[Markw4]

Does a monoblock have to have a pre amplifier?

Generally they don't have a preamp. There is separate stereo preamp somewhere in the system, and then two monoblocks, one for each of two stereo speakers.