[RodB]

Isn't it weird how stuff like this follows you around. Makes you think "should I go to the Home Depot?" They don't sell AKAI at Home Depot.

[MrFixr55]

There is a part of me that would love to hear how these old analog machines stand up to the digital jobs now.  Downstairs, I have a 4 track (4 channel) Akai 3 motor pro job that someone gave me to fix 35 years ago.  I was extremely busy, did not get around to it and lost contact with the person (I don't know his last name and he kinda disappeared.  I feel guilty that I can't return this to the rightful owner.)  One day, I will check it out.  It's interesting that especially if using the big reels and you hit rewind on these, if you hit stop, the reel spills a ton of tape.  I remember in the school radio station that we had one of these rack mounted Akai pro jobs.  the instructions were to hit Fast Forward to slow down the rewind process and to hit stop only when it slows to a crawl before it actually started to fast-forward.

I have a Uher28 stereo R2R unit that I bought for $50 in 1974 and spent another $40 for a new head (open coil).

[morzh]

Honestly, I think that today's good quality digital machines (CD, DAC and even Class D amplifiers, the high end that is) stack up quite well against the tape decks, recorders, vinyl and tube or older solid state amps.

We should not forget that a large part of this love for older technology is our nostalgic feelings for what we were growing up with.
And the Carver challenge successfully proved that solid state can do just about anything, when the pro blind test is conducted.

And, considering that CDs today are on their way out, one day when some quantum dohickey will play through some unimaginable transducer, pulling the music from the Cloud, some folks will be fondly remembering Class D and Marantz reference DAC as "Good old technology with warm sound."

[MrFixr55]

@Dale Cook
Dale, I know that this is a response to 4 months ago, but it turns out that my brother actually has 2 EV 635A Mics, that he bought about 1976 when he and a friend were doing acoustic guitar duo gigs in local bars in the mid 1970s. With my electronics knowledge and owning a 1967 Ford Country Squire wagon, I was their roadie. I don't know if he bought these because SM58s were more expensive at the time or if Sam Ash (a large regional chain store that just went out of business after not being able to compete with Guitar Center) didn't carry them. Bill worked for Sam Ash at the time.

There are currently 2 of these on eBay, very well used for between $235 and $275. The current EV ENG Mic is about $200. I don't know where they are made. SM58s (The real ones, not the counterfeit ones) are currently made in Mexico and are about $125. Our church uses Audix dynamic mics. Nice sound but definitely much more hand noise than an SM58!

[MrFixr55]

@ Rod, I didn't buy a lot of this, and not at Home Depot, found a lot of it on the street on the way to Home Depot.

[MrFixr55]

The Guitar folks still insist on tube equipment, but it is for a different reason. Hi Fi nuts and audiophiles (the difference is that audiophiles appreciate good equipment, HiFi nuts have to have it) expect the amplifier and speakers to faithfully reproduce the program. A guitarist considers the amp to be part of the instrument, especially these heavy metal types that expect to control the level of distortion, which comes from all stages, including loading of the power supply. Some of these folks think that they can tell the difference between a 5U4 and a 5AR4, between RCA or GE 6L6GCs and Sovtek, JJ, Electro-Harmonix, etc., and feel that they can't control the overload and distortion on a solid state amp.

[Arran]

This is a curious attitude as many guitar tube amps originally left the factory with solid state rectifier diodes. I was looking up some schematics for Orange brand amps, and that was what most had, along with the power output tubes in push-pull-parallel, the Fender ones were more conventional with tube rectifiers. In the end it doesn't really matter, a directly heated rectifier tube is almost instant on in terms of conducting, the main difference is in the forward voltage drop.
Regards
Arran

[morzh]

>>expect the amplifier and speakers to faithfully reproduce the program

Yeah. Faithfully.

A tube HiFi amp will have anywhere 0.5%-1% at low volume to 5% THD at high volume.
And yes, a solid state will have 0.01% but can go down to 0.001% THD.

And then it all goes into the speaker that will give you 0.5% midrange THD and up to a few (3-5%) base THD.

This is what we consider "faithful" (yes, human ear ain't that sensitive to bass distortion).

And then there is the tape distortion with R2R and decks.
And inner groove distortion on the vinyl records.

[radiorich]

Hello Mike,
I’ve never seen anyone mention that a tube HiFi amp can have anywhere from 0.5%-1% THD at low volume and up to 5% at high volume. Meanwhile, a solid-state amp might have 0.01% THD, going as low as 0.001%. Also, tube amps tend to produce a more pleasant sound.

Sincerely Richard

[Arran]

I'm not sure what they used as a signal source to measure the distortion levels either, I assume an audio function generator with a series of fixed tones, but there would surely be some variation between generators, and one tube amp, or solid state amp and the next. One thing is certain, there is almost infinite variation between piece of music, and the quality of the recordings, if you tried playing an Edison cylinder record through even the best audio amp ever made it would still sound terrible
Regards
Arran

[morzh]

Rich

Simply speaking, while producing harmonics, a tube amp produces mostly even ones.

A solid state makes very little, especially considering they usually have very deep feedbacks that bring them down.
But if they were to make some, they go into odd harmonics and they will sound unpleasant, unless brought very low (this is on high quality ones go down to 0.01% and lower).

Today's popular way to estimate quality is measuring THD+N, and noise dominates the low power, so THD+N goes down with solid state significantly up to 1W or so, and then stays mostly flat until reaching the clipping region.

[RadioSvit]

Hello guys. An interesting topic about distortion and as always I miss the beginning of interesting topics and am late for them. If anyone is interested, I will share my experience. In the middle... in the late 80s I worked as a technician in the metrology laboratory of a large enterprise and even then I made myself a transistor stereo amplifier according to the Kvod 405 scheme, and as a technician I measured the amount of distortion. I remember well that it achieved the promised distortion of 0.05%. I still have this amplifier somewhere in the attic. And fifteen years ago I experimented a lot with tube amplifiers because I wanted to create their small-scale production. So first I made a measuring test stand for measuring distortion and the harmonic spectrum using a computer and the SpectroLab program. I took many characteristics from triodes and pentodes in different modes and created a database. So - small-signal triodes octal triodes 6SN7 and 6SL7 have a very short spectrum of harmonics - a maximum of up to the fourth and the level of the last harmonic is already at the level of lamp noise. But the level of the second harmonic is very high (2...8%), but it is melodious and does not irritate the ear. The picture is completely different with pentodes - here the spectrum of harmonics can be very long, up to the 11th harmonic. And although the magnitude of harmonics decreases with increasing their number, their perceptibility by the ear increases. And therefore 0.05% of the 11th harmonic will be much more noticeable than 3% of the 2nd harmonic. And most importantly, even harmonics do not dissonant, and odd ones are very irritating to the ear, especially when they have a large number - for example, 9...11...13. Single-ended triode tube amplifiers produce mainly even harmonics of the 2nd and 4th order, pentodes add the 3rd, 5th, 7th and sometimes the 9th harmonic. But their magnitude quickly decreases. Therefore, the sound is harmonious and pleasant. In push-pull amplifiers, the picture is different - both triode and pentode push-pulls mutually destroy even harmonics that are pleasant to the ear, but add odd ones that are dissonant. The sound becomes more dynamic, but uncomfortable due to the high level of odd harmonics. How to fix this? Only by introducing negative feedback. But even a shallow negative feedback of 20 dB kills the dynamics and increases the number of harmonics to the 13th. A closed loop. ) Therefore, music lovers and audiophiles love triode single-ended amplifiers, which have large distortions of the 2nd harmonic, which creates an atmosphere of warm tube sound. ) With transistor amplifiers, it is even worse - due to the curvilinearity of the volt-ampere characteristics of transistors, it is necessary to introduce deeper negative feedbacks of 40...60 dB, and although this reduces the total value of the harmonic level to 0.01%, it increases their order to number 15 and more, which, as is known, are more noticeable than 0.5% of the 5th harmonic. This is where the reasons for the "transistor sound" are hidden. So, much more important for the quality of the sound is not the total value of the harmonics, but their spectrum, when even harmonics prevail over odd ones (as in single-ended amplifiers) and a short harmonic tail, the shorter it is, the more pleasant the sound.
Phew ... I refreshed my knowledge of audio in my memory.

[RadioSvit]

Honestly, I think that today's good quality digital machines (CD, DAC and even Class D amplifiers, the high end that is) stack up quite well against the tape decks, recorders, vinyl and tube or older solid state amps.

Michael, in fact, class "D" amplifiers sound even worse than class B. I do not recommend getting carried away with them. I am convinced that you will not soon find a better amplifier than your Macintosh.

[morzh]

Well, McIntosh is, after all, AB pushpull.

It uses some techniques to eliminate odd harmonics. Magnetic coupling / bias for crossover elimination, unity gain and pretty deep feedback rarely used in tube amps.

[Arran]

How about that, my Philco 3118 and Rogers Ten-12 have, or did have class AB power output stages? The latter set had it rewired into a garden variety push-pull pentode amp rather then "triode connected" as it would have been originally, I want to put it back the other way. I believe that the Philco 16 and 116s had this, the audio interstage transformer is a step down transformer rather then a step up, and that infamous bleeder resistor connected between the B+ and ground.
Regards
Arran