Yes they are. I retired my McIntosh 1500 because the Yaqin blew it away. The thing with tube amp designs is they are all very simple designs and the basic design on most of these are over 50 years old. What has improved in the modern vintage is the tolerances of the support components, that being capacitors and resistors. Old gear used resistors with 10% tolerance and capacitors had 20% or worse. Now components are precision. 1% or better. This makes a big difference in the sound. NOS tubes are snake oil. Modern chinese and russian tubes are just as good today. Perhaps 20 years ago a NOS tube would be a better choice, but today with tube factories back in full production they are making very good tubes. The russian tubes have always been good because russian tubes never went out of production. The Soviets used them in military equipment all along so factories kept pumping out the more common tubes. I run Electroharmonix tubes and they sound fantastic.

Thanks again for the video, so useful especially for layperson such as mysel. Wondering if you've done much tube rolling with your Yaqin and if so, could you share what power tubes you like best?

@@thesoulshakers Still running the original tubes. When they fail I will try some others, but these ones sound fine to me.

These preamp tubes sound fine to my ears.

I have the same tube amplifier. Bought from a guy for $100 because one 10 ohms bias resistor went kaput. Replaced all 10 ohm resistors with Dale brand. I’m in heaven.

Off hand I don't but i am sure they are out there. Guitar amps are a little different. They are biased generally to produce a specific sound as opposed to the cleanest output as a hifi amp would be. This generally means a little under or over bias. Under bias allows tubes to cut off between the push and pull phase swing and that introduces distortion. Over bias prevents the dormant tube from going into cutoff reduces cross over distortion but if excessive will dramatically reduce the life of the tubes and cause heating of the output transformer. So as you can see biasing is important, and it is tube dependent. So if you roll to a different brand or number of tube you need to rebias the tubes.

thanks.

Single ended are always heavily biased. There is no cut off. This is why the transformers tend to heat up and the tubes themselves have relatively short lifespans.

Any multi meter that measures millivolts DC which they all do. A 10.00 meter will do just fine. The test stakes are across the cathode resistor and you are measuring the millivolts across the resistor. I will be doing another one on this amp as it has several hundred more hours on it so it is time to check it again. Now it is in my living room hooked to big speakers.

ElectroHarmonix are what I am running now. I am running the stock preamp tubes.

You set to millivolts if you measure across the cathode resistor. You set it to milliamps if you put the meter in series with the resistor. This requires disconnecting 1 side of the resistor and placing the meter in series with it. Most measure across the resistor in parallel with it and measure the voltage drop, but then you have to calculate the actual current which will vary depending on the value of the cathode resistor. This is why some pureists will disconnect the cathode resistor and measure the actual current, because they don't know ohms law and how to calculate the current from the voltage drop.

Thanks a bunch for your fast reply, I'm not sure how my amp is configured but I was wondering if I set it to the voltage, would it actually show the voltage of the tubes, but I guess one way to find out is to just do it and hope it doesn't fry my cheapo harbor freight meter lol, thanks again for your help. I posted a couple of videos on KZfaq of my audio system and what I've done to the amp. Just type in Woodnesium in the search box.

@@lysanderhubbard6863 You measure the voltage across the cathode resistor which goes to ground. Generally about a 10 ohm resistor.

@@12voltvids thanks, but I'm not going to open this thing up, I will just stick the probe in one of the 4 holes on top, then set the meter to volts and see if anything happens :) I'll let ya know what happened.

Single ended is idling at about 50% max current with no signal present. Mist have ni control, they are set with fixed resistors.

@@12voltvids thanks. Just got a Class A single ended tube amp from a thrift store. El34 tubes. It sounds very detailed bright and full. Nothing missing in the sound. I did a comparison, same for same, with a 70s solid state sony reciever and see the colouration the solid state has especially in the lower frequencies. Both amps are sounding so different but both are beautiful sounding.

I don't know

I have never rolled to these, so I can't tell you what the bias voltage should be. However, at 400v plate voltage, an EL34 requires about 38mA and a 6550 53mA. The yaquin runs a plate voltage around 430v. Nor remember many of these bias calculators, and figures pulled from the internet are geared towards guitar amplifiers, not hi-fi amplifiers. Changing the bias current will certainly have an effect of sound. Too much bias will increase the distortion. Too little and the tubes will run hot, and this will shorten the life of the tube. If the bias is really low the plate of the tube could glow red. This is very bad, as it is not only burning up the tube, but could also heat up the primary winding in the output transformer, melt the insulation, and then you have a shorted output transformer. Since I have only run the original tubes, I can only comment on the recommended settings for the supplied tubes.

Volt

+Pieter van der Meer If a class B amplifier is biased into cut off then you are correct, you fall into the dead zone. Most push pull designs are not class B, they are class AB where there is a slight bias voltage applied to tubes or transistors to keep them from going into cut off under a no signal condition.If the bias is set too low, you get the switching distortion as the output goes into cut off before the other output begins to conduct "dead zone" If it is set too high, too much idle current will flow which can damage the tubes, and output transformer, and overheat output transistors.Clipping distortion occurs under an over drive situation, where the power supply can not supply enough power for the output level.The switching distortion or IM happens at all signal levels, not just full output where clipping distortion would occur.

+12voltvids There are a couple great sounding class B tube amps..One is called the Berning EA 230 and there is one other that escapes me...Actually Mcintosh runs very close to class B at idle on the unity coup0led bifilar amps..I just rebuilt a pair of Mc30s and now I'm doing a pair of Mc60s...Love your videos BTW.

+Mike Samra A class AB is just a class B amplifier that is biased slightly higher to keep the tubes slightly conducting. Most so called class B amplifiers are in fact class AB.There were a few exceptions in some solid state amps back in the 80s by Technics and Yamaha. They called them auto class A.At low power levels they would switch to a single ended output, and use a single transistor for the entire waveform dramatically decreasing efficiency, but also removing the crossover distortion. As the volume was increased the amp would go back to class AB.A class B amp is a total cut off, so there is no idle current, and they sound pretty harsh. Many cheap transistor radios used a class B push pull into an output transformer. The reason they did this was so there was no idle current wasting battery power.I have a VERY OLD Sony transistor 6 AM radio that I am going to show off some day. It was my grandmothers set, and she used to listen to that thing every day, all day, and a set of batteries lasted for weeks at a time. Class B output, very efficient and being an AM radio, sound quality was not a concern.If I bias this amp as class B, you can definitely hear the difference (that is bias the tubes for cut off under no signal)

12voltvids I agree with you about the sonic differences between A/B and class B. There are a couple of very good tube amps that class B output stages and one is the Altec 1570b and that runs 811s or 572bs which are zero bias triodes. We actually built the driver stage with a 12Ay7 input going into a 6sn7 and from into a pair of EL34s wired in triode as a cathode follower drivers into the 811s. Of course the driver runs in class A but we were able to tweak out a slight notch distortion in the output with 2 watts output at 1khz..Normally these amps are 190 watts but go down to about 50hz at that power but when you do all the mods you can get it down to 20hz at about 90 watts. The output is not large enough for 200 watts at 20hz but it has beautiful bandwidth if you biamp them.. I like pure class output stages as well but they waste a lot of power..Class A/B is about the best overall. parttimeaudiophile.com/2014/07/29/caf-2014-live-sound-designs-makes-the-old-new-again-and-the-crowd-goes-wild/

They are indeed. My Chinese amp sounds every bit as good but you will never convince the audiophools this. But then the only people that say this are the people that can not afford a McIntosh. I happen to own one myself. Some day I will do a video on it.

@@12voltvids I can but your ears can't hear what it can do. It is just a waste to have it and not be able to hear it.

@@ChickenPermissionOG Actually I can hear it. The modern tube amp i use has a much better sound that. My old vintage.

@@12voltvids Unless you are a dog you can not hear it.

@@ChickenPermissionOG i certainly can. The vintage amp sound changes fairly significantly over the first hour or so after it's first turned on as it gets completely warmed up. The reason for this is old equipment from the 1960s is full of carbon resistors. Most are 10 some 20% tolerance. As they heat up their value changes slightly which in turn effects the sound quality. My modern amp it's all thin film better than 1% tolerance resistors. So from the time it's turned on and functional the sound quality never changes. Now if I were to go into my Mac and change every resistor to a new one then I could probably improve it's performence as it stabalizes. But as it sits now if I want to listen to that unit I have to turn it on and leave it sit turned on for at least 30 minutes. Now of course it will work as soon as the tubes warm up but it's certainly a much fuzzier sound until it fully warms up where is my modern tube amp as soon as the tubes drop the temperature it sounds fantastic and it sounds that way all day long. Does it sound better than my solid state app? I would say no it doesn't it has its own sound which is very pleasing to listen to compared to my solid state app which sounds very sterile. That's the main reason why people pay big bucks to buy vacuum tube gear, it's not that they're better on spec they're not, however they are much more pleasurable to listen to.