I'm not seeing the schematic, but I would thing R7 becomes 34k.
Yes, they do. A good CD player can deal with some scratches. I used to test them by taking a CD, making 6 deeps scratches with a knife from centre to outside. If it played, I'd consider buying it.
Before that, they were wax.
https://cen.acs.org/articles/94/i24/Groovy-chemistry-materials-science-behind.html
Yes, an oscilloscope is more versatile, and can handle higher frequencies than a sound card. I do always use a sound card when I want to measure distortion though. Some oscilloscopes can do that too, but those are rather expensive.
Therefore, my preferences are, in priority order:
1) Full autonomous oscilloscope, if money is not an issue.
2) PC oscilloscope, like the Hantek.
3) PC software with sound card.
I ended up using 1) (oscilloscope) and 3) for signal generation and distortion measurement.
I assume you mean this one: http://www.r-type.org/articles/art-008.htm
There is nothing wrong with the topology, voltage amplification stage+LTP phase inverter+push-pull output stage.
But I do not like Elektor Electronics implementation of that topology, mostly the choice of tubes for the LTP, and also the fact that they use 4 tubes, for an EL84-based amplifier. There is no need for such amount of gain. Just a simpler 3 tube one, a double triode (or triode-pentode like the 6F12P or ECF80), one triode for voltage amplification, another triode as a cathodyne phase splitter and the two EL84s. That's it. That's basically Tubelab's SPP. No need for more than 3 tubes for such an amp (I'm not counting the rectifier tube).
Yes, that's the right approach, at least in my view. And even if satisfied, you can build another one 🙂. I myself find the process of drilling wholes, mounting tube sockets, transformers etc to a chassis, doing the wiring, powering up the thing for the first time etc a very enjoyable and calming experience.
Sorry, I used the colon as a separator. Just a voltage divider like this:
Your input is 10V, the output is roughly 1/10 of the input (0.909V). You can of course select the right value of R1 to get exactly 1/10.
Provide it again, silly of me to think go back and dig it up.
That is amazing the difference. 😳
Was there a brand that stood out? Just curious...
I do know this. A cousin by marriage of Oma's generation collected gramophones (if recalling the name of the player correctly, I was about 14 years old) and wax cylinders, the Las Vegas newspaper said he had the largest collection west of the Mississippi River. Slim passed before I got to meet him and his collection of gramophones was sold to support his wife, except the most special. I was fortunate to get to hear one, a very unique sound.
Thank you for expanding and making it so clear! 😀
Are you saying the design should have slipped on tube and went from EL84 to a tube with more output?
Can there be too much gain?
Okay. Note the word "can." 😉
Neat.
Understood.
By the way, first time you mentioned the voltage, looked for the maximum the sound card can handle and didn't find anything stated.
Honesty has nothing to do with it. It presents a logical argument for the viewer to consider. The main reason I responded to your question with them as provides another way to evaluate tubes and solid state without opposition; they each have their merits.
Now if wondering about Steve's background, a simple internet search will produce a plethora of information.
By the way, plan for the updated system, it will be bi-amplified, with the base driven by solid state and the mids and highs driven by tubes.
In the schematic shown, if you wanted to parallel the ECC83, you would make R11 and R12 50k, and R7 would be 34k. The voltages would be the same but there would be twice the current.
Of course in the above, there's no reason to do that - a single ECC83 will work.
Philips comes to mind.
Of course the best solution is to rip it on a computer since there's jitter correction etc. I've ripped CD's that don't play anymore. The damage shows up as blank spots but the timing is preserved. Depending on the music, you can then cut and paste a replacement from another part of the track (electronic music).
We were discussing converting from ECC83 to 6F12P, as seen here:
One is acoustic music and the other Sargent Pepper. I could even use the 3mm to RCA to then play the digital file.
No, we were discussing how to parallel tubes.
In the above schematic 6F12P isn't suitable. It's better when used for split load. LTP wants two identical halves.
The triode in 6F12P is like 10X 12AX7, the pentode is similar but not identical when triode connected. I should have been more clear.
Then why bring it up at all? I am confused how it applies to the conversation...
How can we be discussing something when the term parallel tubes was not mentioned? Only ask to improve my communication ability and avoid future inefficiency.
Why parallel tubes?
Well, it goes both ways. If you use more powerful output tubes, then you need a bigger signal to drive them. For example, in my amp I use 6P3S-E (Soviet tube, has no exact western equivalent, but looks like a 5881), ultralinear connection, it requires about 80Vpp (peak-to-peak) input from the phase inverter to reach full power. That is ~4 times more than you need for an EL84.
I think soo. Too much gain may result in an unstable amplifier, and you need to have the gain that you require and not much more. Most signal sources these days can supply 1V RMS, therefore there is no need for amps with big gain. There are, of course special cases, like for example a microphone, or a pick-up from a record player, but for those I'd design a separate pre-amp, keeping it away from the power amplifier.
PS: Just to make things muddier, there is open-loop gain, when your negative feedback is not connected, and closed-loop, when negative feedback is applied. Open-loop gain is always higher.
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The mathematics behind this is very interesting. Essentially, there are a certain number of errors that can be corrected with 100% accuracy (i.e. the bitstream is guaranteed to be perfectly correct) due to the mathematical design of the encoding. If there was no error-correction capability, the slightest scratch would cause problems. This is a key reason why digital storage is technically superior to analog - any errors/imperfections in the analog process (wow/flutter/manufacturing tolerances/etc.) can never be removed. Of course, there is a certain level of error in analog that is acceptable because we cannot detect the difference, and there is also some "error" that some people desire.
A CD player with poor quality components (motor wobble, laser timing accuracy, etc.) will introduce errors in addition to the scratches that may be present, and make it more likely that the error threshold is exceeded and the bitstream cannot be decoded. Since the tracks on a CD are laid out the same way as on a vinyl record, light scratches that run radially (from the centre outward) are rarely a problem since the damage only affects a small amount of consecutive information. Deeper scratches are worse purely because they are usually wider.
As I said previously, all my equipment puts out no more than 500mV RMS (tuner and tape deck). Since the TubeLab and probably the L1 are designed for 1V RMS, then seems there be the extra cost of a pre pre amplifier (as I understand, all the tube amplifiers are integrated).
The same reason you parallel anything else 🙂
The main reasons being either two small ones are cheaper than a big one, or they don't make anything bigger.
Sometimes in a tube amp design, someone will design to use common dual triode tubes but they only need one triode. So you either use one half but not the other (wasteful) or parallel both to make use of it.
Sometimes, like in my case, you want to make an amp larger than is possible with just two tubes in push pull. That becomes parallel push pull.
Sometimes it's just cheaper. My Stupendous amp is a good example - 4 parallel pairs of 6P1P tubes per channel (with load balancing resistors to avoid current hogging) to make roughly 10 watts of class A using tubes that were $1 each at the time.
It still remains to be one of the least expensive (but excellent sounding) 10 watt class A amps you can build - tube or otherwise.
With regard to the schematic you posted, a 6F12P circuit like this can replace the EF86 and ECC83 part of it - everything on the left side of the drawing except C2 and R4 and still in theory work better while saving money.
It can swing over 150Vpp in this config, it also scales well so it can work at the lower voltages in that schematic, too.
R2, C7, R14, C6, and R1 make a 2nd order high pass filter to get rid of subsonics. The poles are purposefully far apart to improve phase shift.
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Well, in my simulation Tubelab SPP reaches max power with in input signal of 0.354V RMS (0.5V Vpeak). Do you have a reference for the 1V RMS with Tubelab's SPP?
That's quite a bit far from the goal of at least 10W per channel.
Common cathode resistor for the output stage means you need properly matched tubes. I would use separate ones for each tube. In general, I do not see it being simpler than SPP, and ECC99 seems to be an overkill to drive EL84s, even triode strapped.