I fixed up a Siemens cinema amp. 2 x EL34 Class AB 800 VDC. Choke to 2 x EF41 ( ? ), raw DC to power pentode. 100 watts genuinely. 9 dB feedback, 100 V line with 8 ohm 10 watt tap. 1 watt 0.13 % THD, 10 watts 1%. 100 watts 10%. The cinema could use 5 watts 95% of the time. The sound was like a big valve radio. It had a low/high HT for instant start via relay to the projector. 4 valves, the 41s in long tail pair. One has to infer very high distortion without feedback. With 110 dB /watt/metre 1 watt speakers it would be plenty. The valves were very blue. Siemens EL34 were best. National East German limped along. Germany was 220V in the 1950s. It used the pentode way of working to reduce power supply requirements. I admired it as good engineering. The sound was OK. Open but like the speaker voice coil was not 100% on centre.

Your dedication to the craft is impressive. I love tube amps, and I have a few completed projects. I'm too much of a rookie to design my own, but I do love building proven designs in my own style.

Im glad you managed to get the lows working better, I do have to say though that is one awesome amplifier

David, your work has been great, as has been this discussion. Certainly, it has served, and will continue to serve, those who wish to embark on a similar project and not "reinvent the wheel". We no know what results with a small driver and with a transformer driver as you've used. We'll learn what happens when you get it converted to cathode drive. In the process, we'll all learn a great deal from your efforts. Thank you already, as well as to others who have done homework and contributed.

@ElPasoTubeAmps

8 жыл бұрын

+Albert Nakaji Thanks, Albert. That is indeed, what I hope to accomplish. There are many suggestions made but nothing speaks like real built circuits and honest measurements. Many of my attempts to build amplifiers are much less than perfect but that is the way life is. We often see these outrageous specs, for example, OPT on Ebay and they may be that "perfect" for small signal analysis (0 dBm level) and they can state 10 Hz to 50 KHz, etc. but once the circuit becomes real and the power level reaches more than a watt or two, performance isn't so perfect. I hope my videos actually encourage others build with a realistic expectation of performance. Much too much is claimed for performance concerning some of these amps I see everywhere on the Internet. Thanks again.

I love your work. the most beautiful equipment in the world. you are a GENIUS

You mentioned using a lower mu triode in the front end to reduce gain and/or stabilize the amp. I did the same, and didn't have to change any values. It worked perfectly to stabilize my 20wpc amp. I replaced the 12AX7s with 5965 (12AV7) tubes in the cathodyne splitter circuit.

Excellent work .. i have seen never seen in the world . you are a GENiUS. ... .... Awsome

Nice.A home built Altec 260A. The 6Y6 makes a very good driver tube for those 813's

بہت خوب ٹیوب ایمپلیفائر بہت زبردست پروجیکٹ ہے

Oh yes always my favorite, the hot plate special🔥🔥🔥 Good song too👍👍👍😁

Wow!! El Paso, my congratulations, still learning my man Les G4XMX Tarporley UK.

I would love to see these in operation!!!

Nice work!

That looks like some serious power. Looks totally bad ass

@ElPasoTubeAmps

3 жыл бұрын

Basically an 813 is the nuclear version of the 6L6 that runs at a plate voltage of 2500 volts. It is a serious tube. Thanks...

That's some cool stuff!

lol that kind of power reminds me back to the futur movie ahah very nice

I finally finished 2 of my amplifier builds

I can see from the scope with sine wave that there is saturation at high output instead of nasty clipping that is characteristic of solid state amps. I think that is why it sounds acceptable even at the heavy overdrive levels.

wow ..amazing....

VERY cool.

beautiful

@ElPasoTubeAmps

8 жыл бұрын

+jeremy crow Thank you.

Amazing.. Thank u

It might be worth it to connect the oscilloscope and THD meter to the DRIVE TRANSFORMER. The output transformer is passing quite a bit of current into the dummy load resistor, but the drive transformer is driving a very high impedance. So high, that the non linear inductance of the transformer due to amplitude becomes very apparent. Putting a load on the drive transformer, basically a resistor across either the primary or secondary winding, just to create a linear load for the current proportionate drive from the plates of the 5881/6L6 drive tubes. I though maybe, that you were seeing the "kink", which often occurs when the plate voltage crosses below the screen grid voltage of the 813 tetrodes, but if that were the case, it would occur at any frequency. Another thing to look at, is to make sure the coupling capacitors are high enough value, for the impedance of the coupled circuits. The final culprit, may be core saturation of the output transformer. That would explain the anomaly becoming worse, as the frequency goes down. I'm not seeing a lot of iron for the high output power. Every time you double the amplitude, you increase your low frequency response by 1 octave. That means, that at low listening levels, you would have no problems down at 20 Hz. Double the volume, and the "wheels come off" at 40 Hz, At 2,700 volts, a possible plate to plate voltage of nearly 5,000 volts, you may not be able to drop below 200 Hz. Comparing the output of the drive transformer to the output of the speaker transformer would tell you exactly what's happening, when you try to drive low frequencies at full amplitude. I don't think the 813's are letting you down, I think it's the iron. Do I dare suggest a little negative feedback? especially for the DRIVER stage?

@ElPasoTubeAmps

5 жыл бұрын

Your comment may inspire me to bring this 813 amplifier back to life. I still have it and can slide the 3-400Z RF amplifier out of the cabinet and put the 813 amp back in, and I still have the screen and bias supply that is built on an outboard chassis. Kind of amazing I have kept all these items in tact and have not parted any of them out for another project. I think, this time, I might change it to an impedance drive with a 2500 H CT choke that i did not have at the time of this video but I do have now, and I probably have a nice UTC input transformer also and basically follow the Altec 260A design. Since this video, I have also changed the filament transformer to two separate transformers and I am able to adjust the cathode current on each 813 separately and if I remember correctly, this made a considerable improvement in THD. The plate transformer was originally from a ship-to-shore Navy amplifier running PP 810's if what I was told about these transformers about 45 years ago when I acquired them is true. I don't know the actual rating but I would guess around 500 watts. If you have seen the video on the 3-400Z amplifier I used these OPT in, I was getting 1300 watts out of them at a plate voltage of 3500. I especially like your idea of putting a linear load on the driver transformer. I can see how that might help as the impedance is high and it is running class AB and is not drawing any grid current. In this video I am using a "Poseidon" driver board driving the grids of the 5881 and I did add in some NFB but, again, if I remember correctly, it was not behaving very well. I need to take a look at that also. Thanks for your comments and suggestions. Attached is a schematic of the Altec 260A and notice that they drive the 813's with 6AU6's... www.vintagewindings.com/gen%20pop/8299543VW8335/Altec/Altec-260A.pdf

@vincentrobinette1507

5 жыл бұрын

@@ElPasoTubeAmps Some very interesting things about this amplifier. The first thing I noticed were the published specifications. At 10 watts, the frequency response is the full 20-20,000 Hz. At full power, the bandwidth narrows to 45-15,000 Hz. Clearly limitations of the output transformers. Another strange thing, is the magnetically coupled inductor, used between the driver stage tubes and the grids of the output tubes. I do believe, they are using the inductors, to keep full supply voltage across the plates of the drive tubes, to allow much more amplitude swing to drive the grids of the output tubes. Resistors would only allow 1/2 the available amplitude to drive the grids. The inductors are, however, dampened with 100 K Ohm resistors. There is no real phase inverter in this amp. The input transformer drives the entire amp balanced line. There is some balancing in the first stage, because the cathodes of the first stage are tied together like a long tail inverter. another feature, is the full field negative feedback. It uses its own separate winding on the output transformer to the cathodes of the first stage, creating a true balanced line feedback loop. Filamentary Pentode output tubes: REALLY! I've never seen anything like it before!(I was under the misapprehension that 813's were triodes)They did get a couple of things right with that, mainly driving the cathodes from separate taps on the filament supply transformer, then using the center tap of the transformers for ground. That keeps (most of) the hum off the plates of the individual tubes. The fact that there are two tubes on a push pull transformer means that the slight 120 Hz hum cancels, leaving zero hum on the output to the speaker. They do have a bias adjustment on each output tube. This is a fascinating amplifier. Thanks for sharing:)

Your channel has inspired me to use some of my 829b's as an audio amp. I literally have a case of them and as I'm not too big on making transmitters... So yea, thanks for the inspiration.

@ElPasoTubeAmps

5 жыл бұрын

I built one amplifier with the 829B back in the 1980's and I still have it but it is the classic VHF amplifier for 2 meters. I quickly looked for the schematic on line but it is pretty old and can only be seen in the older radio handbooks. It used the large U shaped plate tuned circuit and it works. I also remember it TGTP design so it could be sensitive to parasitics if not neutralized. I used a small coax T/R relay and some of the carrier (FM) to actuate the relay so it was "automatic" on/off. Maybe I should make a video of it for the ham radio group. I think I could get 75-80 watts out of it so you should do well using it as an audio amplifier. I think I ran the plate voltage around 850-900 volts so the plate Z would be up in the 10K+ range for audio. A powerful little push-pull tube in one package. Stay safe.

@tayro7265

5 жыл бұрын

@@ElPasoTubeAmps Any schematics you have would be greatly welcomed. I have a total of one with 829b's as outputs for an audio amp. It uses 6sn7gt's to drive the 829b's. which fortunately I have a box full of as well. However it is a billionth generation copy that is impossible to clearly make out. The only reason I know what types of tubes/valves that are used is because they are in bold print. The two first stage pre-amp tubes/valves who knows? Resistor, capacitor and voltage values are anyone's guess. Not a good start. I've gone through the Radio Museums collection but unfortunately nothing.

@ElPasoTubeAmps

5 жыл бұрын

@@tayro7265 I don't have or remember seeing any particular schematics for 829B audio amplifiers but a search shows up more than I expected. Here are a few. www.finaleaudio.com/829b-special Here is one from Pete Millett's site. He makes some really nice equipment and there is a link in it to a schematic that you can use as a model. www.pmillett.com/829b_amplifier.htm www.pmillett.com/images/829b.PDF

My dream is to go to a SPL competion in the winter and use Tube gear for it.

At 7:48, in the diagram, the cathode of the 6X5 is missing. I think you meant it to go to ground. The LM334 constant current sink on your 12AU7 differential amp is a nice addition, but you might get improved performance by taking it to a negative supply rather than ground.

again hi sir i want appreciate of you bacaus you lead me...thanks alot and iam a fan of you..thanks sir

where do you get your? and will you show the prints of the circuit?

limiting means the bias is wrong seted?

Could you fire up the spectrum analyzer and show us the distortion harmonics now that they in the 1%+ range?

@ElPasoTubeAmps

8 жыл бұрын

+bigzaps I can do that. I will make some spectral measurements now and then after changing it to a cathode follower driver circuit, as has been suggested, make some more measurements for comparison. The reason I post this stuff is this is what I would want to see if I were building one (like I am...) but first wanted to research and see the differences in design and construction. My hopes are this "research" will help others build their own equipment without so much experimenting. I do see some nice equipment builds on KZread but rarely do I see any legitimate measurements to verify the performance.

I'd like to buy it for my son . Hes a amazing 18 year old guitarist that plays anything you want . Hes been asking me to find him something . Let me know thanks

Where would you recommend sourcing output transformers for this style of project? I've looked into some creative solutions that would fit the ratio and power requirements, but I'm having difficulty meeting the higher working voltage requirements.

@ElPasoTubeAmps

7 жыл бұрын

I really don't have a good answer to where truly high quality, high voltage transformers can be purchased. As you probably notice in most of my videos, my transformers are generally military surplus. I approach this hobby in a reasonable cost-saving manner and I know that buying large OPT transformers new are likely to cost $$$. I can't ever recall ever seeing output transformers like this for sale on Ebay. With that said, I have been told by a few people that custom transformers can be purchased for a few hundred dollars each but something like this OPT would cost a bunch of money - probably more than most people would want to spend and I would be suspect of the true HV rating of a new non-military grade OPT being used in the 3 to 4 KV range. Sorry I don't have a better answer.

@Subgunman

6 жыл бұрын

Find who bought out the Peter Dahl line of transformers. They will have transformers for most anything but be prepared to pay big bucks....

Sip......boss

schematic ? thank

BTW, as far as I know 800 V EL34 isn't possible in UL mode, flashover. LS50 more ideal ( Gu/Fu50 ). GEC TT21? 807? 800V a mad choice.

With music I would not go over 50 watts RMS. Try it with a pair of 833's . I know a few hams that use 813's in transmitters. I saw one with a pair 833 driven by another pair 833. You can hear these guys on 75 meter AM

@ElPasoTubeAmps

5 жыл бұрын

I built my first higher power RF amplifier around 1970 using an 813 and plate modulated it with a pair of 813's. Beautiful tube and I have probably ten of them at this time. I really should build something with them. I have a 833A amplifier posted on KZread that you might like. I only use it on 20M but it is beautiful and works great. Wow... a pair of 833's modulated with another pair. That is real AM. Again, back in the early 1970's I moved up from the 813 to a 4-400A running class-C and plate modulated that with a pair of 4-400A's and I ran it on 75M. It was a great time. This was back in Huntsville, AL but I have not built any AM equipment since then. I ran RTTY for a number of years but now I am back to just SSB on 20M. Thanks for your comments.

Maybe the 833A tube is for use in VHF transmitters and not audio would I be right.

@ElPasoTubeAmps

8 жыл бұрын

+DAVID GREGORY KERR The 833A tube was (is) primarily used in AM radio stations operating in the 500 KHz to 1600 KHz band (what we think of as the standard AM band) as an RF amplifier and modulator. A typical 1 KW output commercial station ran two of them in the RF amplifier and two of them as modulators. There used to be lots of these stations in small towns all across the USA. Maximum frequency is 30 MHz so they don't use them in VHF or UHF equipment. A pair of 833A's can deliver 2700 watts of audio power.

@vincentrobinette1507

5 жыл бұрын

Tubes don't really have a specific purpose, but rather, a characteristic. If you build around the unique characteristic of a particular tube type, it can serve in just about any application. Audio is very popular right now. Tubes designed for high frequencies make good audio amplifiers, if you can linearize their characteristics. Less phase shift, makes it easier to employ negative feedback, without risking oscillation. especially at the upper end of the audio spectrum.

You are the loading the 12AU7 voltage amp with a 10k resistor? Were you overloading to make you choose that value ? I usually load a 12AU7s with 22k to 36k depending on how much I want to swing from the tube.

@ElPasoTubeAmps

8 жыл бұрын

+Mike Samra Yes, I know that will keep the gain pretty low but that is what I wanted. I will revisit the design in the future. I have already swapped out the 10 volt, 10 amp filament transformer for two 10 volt 5 amp transformers and put separate bias controls in for each 813. I monitor the cathode current the same way the Altec amp does by measuring the voltage across precision 1 ohm resistors. The 813's I have are amazing balanced (matched).

@mikesamra9126

8 жыл бұрын

+ElPaso TubeAmps Did you actually have an Altec 260a?

@ElPasoTubeAmps

8 жыл бұрын

+Mike Samra No, I never had the 260A. I had a Altec 1759B (pair of 811A's) but sold it to a fellow in Australia over Ebay. I took some ideas from the 260A for my amplifier like the dual filament transformers so I can monitor the cathode current in each 813.

@mikesamra9126

8 жыл бұрын

ElPaso TubeAmps I have 6 1570b altec amps and 4 1569s

you are perfect

@mohammadmoezi3813

2 жыл бұрын

thankyou sir for lead me...

Howdy. That is not a tube amplifier. That is the Star Trek Enterprse ...

will you send prints of this circuit to me

VerynGood friends Brazil, Sam poul

Forgive my ignorance, but every video of this project I've seen shows these tubes near-red-plating... Are they supposed to run like that, or is that some parallax from lights in your workshop?

@ElPasoTubeAmps

8 жыл бұрын

+Britt Rossman You are seeing it correctly. An 813 is not supposed to show any red in the plate either for CCS or ICAS ratings and mine do show a little red. The higher power tubes like the 4-400A family of tubes do indeed run orange hot and are beautiful and require forced air cooling. I do have a fan blowing across my 813's so that should help a little. I also need to make some temperature-color adjustments to my camera as I have noticed that the plates tend to show a purple type of redness when actually it is a dull orange.

@singhpk99

8 жыл бұрын

+ElPaso TubeAmps It is the tube seals that need to be cooled. Check the old EIMAC and RCA manuals. Blow air down from the base into the sockets and base of the tube

I want to build a dual mono block audio amplifier using 2 810A tubes in push pull per channel for output wanting to achieve around 250 to 300 watts per channel... Do you have or can provide any drawings to construct one?

@ElPasoTubeAmps

6 жыл бұрын

You are a man after my own heart with the high power stuff. The two large transformers I have were originally used with 810's at the power level you are talking about. As for schematics, basically you find modulator schematics. There is nothing complicated about these amplifiers. You need a 2500 volt plate supply and a bias supply that can deliver 100 mA or more of grid current. The 810 is a medium gain triode and needs something in the range or -60 volts bias. Often times we derive this bias voltage from a 100 VA, 1:1 isolation transformer and a variac on the primary. Just build large. I love the big amps. The problem is the output transformer. According to the RCA tube manual, you need a 11K to 12K primary for the output transformer and I assume you want to match it to 4, 8 or 16 ohm output. For the 6L6/6550 family of tubes, if you choose to use a 3.6K or a 5K or an 8K primary transformer, nothing much changes but... at the high power level, correct transformer impedance's are Very important. This can be a challenge. Power supply transformer transformers are really no problem. I am in the process of building a 833A RF amplifier and have almost finished the PS. This will be my third cabinet where I have built a versatile power supply where I can slide in different RF and AF amplifiers above it to experiment with. I will be happy to help you in any way I can. I generally draw up schematics with LTSpice. If you have that program (down loadable for free) I can send you the schematics that I have as a single file that you can just click on and open. Some of the schematics I draw are for schematic use only and can not be simulated in LTSpice. Keep in touch.

@ElPasoTubeAmps

6 жыл бұрын

Check out page 12 for a simple schematic for the 810. www.nj7p.org/Manuals/PDFs/Tubes/RCA-gfat-1942.pdf

@stevenzagony6187

6 жыл бұрын

Thank you! Do you have an email that I can get?

@stevenzagony6187

6 жыл бұрын

Just downloaded LTsplice... Just need your email if you can provide it. Thanks!

@ElPasoTubeAmps

6 жыл бұрын

TheAudioShop@SBCGlobal.net

Have you ever heard of 813's being microphonic, in a linear amplifier?

@ElPasoTubeAmps

9 ай бұрын

No, can't say that I have but I would assume they could be microphonic. Altec makes the model 260A 813 amplifier. That is the only one I know of besides the ones I have built. You would want to tap the side of an 813 with a long wooden stick... 🙂

Será que daria pra fazer um amplificador de guitarra com essas válvulas?

@ElPasoTubeAmps

Жыл бұрын

A guitar amplifier could be made with the 813's but the plate voltage at the top of the tube is deadly. It would have to be built into a safe cabinet so no one could accidently get inside the cabinet and be electrocuted. Google translate English to Spanish 🙂 Se podría hacer un amplificador de guitarra con los 813, pero el voltaje de la placa en la parte superior del tubo es mortal. Tendría que estar integrado en un gabinete seguro para que nadie pueda entrar accidentalmente dentro del gabinete y electrocutarse.

Well done project. Congratulations. Why did you not go with directly driving the 813s with the 5881s via cathode? Wouldn't that have eliminated the transformer, and perhaps given you better distortion figures? I believe it was suggested before.

@ElPasoTubeAmps

8 жыл бұрын

+Albert Nakaji I think that would be one good solution. Since I did happen to have the transformer, I thought I would try it. Who knows, I may reconfigure it anytime... :-) I drove my big amp with 3-400Z's with a transformer and got a very similar waveforms when the amp was reaching maximum output. I am wondering if that is characteristic of transformer driven grids. On the other hand, the 3-400Z amp was Class B and drew lots of grid current and this one is AB1. As was mentioned in a few posts from viewers, even though this is AB1 the grids of the big tubes are not happy with a high Z voltage source. It is pretty interesting how Altec drives their 206B amp with a pair of 6AU6's. With that in mind, I really can't (and don't) expect this level amplifier to be much more than a big PA amp. However, I bet it would be good for lead guitar but not as a big bass amp. Even though the lows are much less than perfect it sounds good. As long as we are not making abrupt changes in the signal (as in clipping, notch distortion, square wave, etc) the sound is not harsh and objectionable.

@tubical71

8 жыл бұрын

+Albert Nakaji that´s what i´m saying all the time.....;)

@tubical71

8 жыл бұрын

+ElPaso TubeAmps read my comments on this in the previous video, there i´ve described the behavior of that choke driven thing. And why this is not a very good choice.... You´re really, really, better off, when powering DHTs with a cathode follower...if you do so, you wouln´t have all these "errors" remaining in our output signal... It´s all about the grid impedance and their current draw of these 813 tubes. The impedance is dropping from several 100kOhms to about several kOhms down to several 100 Ohms while you push them - you need to deal with this in order to have a clean output even at nearly maximum power output, this is where good/bad drivers will be divided....

@ElPasoTubeAmps

8 жыл бұрын

+Albert Nakaji Well, from what you guys are telling me, I will just have to try the cathode follower. I won't have to change much or add any significant components and once I get it done and tested I will post the video again so we can directly see the difference between a PP plate to PP grid transformer driven circuit vs a PP 5881 cathode follower circuit into an amp of this size. Thanks again for all the suggestions.

@ElPasoTubeAmps

8 жыл бұрын

+TubiCal I appreciate your suggestions and I am going to try the cathode follower and we will be able to see the difference. I am hoping it will improve the lows a bit more. As I mentioned, it actually sounds good (you can tell it is a Big amp by its sound) and really has command of the speakers. I am driving it with a SS Dynaco preamp. My NFB is down around 7 dB if I remember correctly. I might need to increase that slightly but have to be careful that it doesn't get the "fuzz" on the LF signals like I have seen before in amps with too much NFB.

It's all fun, but stay with reliable models, example, WE or Altec or Williamson style. Use published documents by transformer makers.

where did you get the parts?

@ElPasoTubeAmps

4 жыл бұрын

I would be happy to send you schematics but I rarely ever draw them anymore. I buy the aluminum chassis new from www.mouser.com and the rest of the parts I pick up at estate sales, from other ham radio operators, some from Ebay and so on. The big output transformer I acquired around 1970 from a friend at work when I worked for NASA in Huntsville, AL so, there is no one place to find all of these parts anymore. Hope this helps.

You can probably hear the output transformer lamination sing in absence of a monitor speaker!

@ElPasoTubeAmps

8 жыл бұрын

I know what you are saying. I can definitely hear the transformer laminations on the smaller amps that I have in the 1 KHz to 5 KHz region but I don't remember hearing this one. The transformer is pretty massive and probably is full of tar so that may explain why I don't hear it. I believe the transformer was originally made for PP 810's. I have thought about building the 810 amp but maybe I have satisfied myself with large amps for the time being. Thanks for your comments.

@TecsPlusLLC

8 жыл бұрын

I see what you mean-it was sealed, right? l used to do broadcast engineering years ago and I would balance the modulator tubes o the station's 1KW nightime transmitter (833A's) by listening for the minimum amount of "singing" of the modulation transformer which was an open frame style.

@ElPasoTubeAmps

8 жыл бұрын

You had the job I dreamed of when I was young. My career was in computers from Jan. 1970 to Sept. 2010. It was a great career but I always thought I was meant to be an RF engineer for Collins Radio. I have no complaints but I still love the smell of the old equipment and sizzle of high voltage. I know some fellows that worked around transmitters and, usually only once, got the shock of their life and lived to tell about it with scars on their fingertips and elbow. The ham radio operator I got these transformers from back in the early '70's was a ham and a chief at NASA in Huntsville that liked to tell the story of how he got across some 866A rectifiers and lived to tell about it. Fortunately, I never got the multi-kilovolt shock but I have been severely blasted by an old Heathkit DX-100 that I almost didn't live to tell about. I had replaced the modulation transformer with one from an ART-13 and ended up with the HV ceramic feed-thru terminals that come out the side of that transformer on my left wrist when I tipped it up on its side and turned on the switch with my belly. Obviously, I did not have it unplugged. The pain, taste of aluminum in my mouth and the smell of my own burning skin will never be forgotten.

@hennypoort9395

7 жыл бұрын

TecsPlusLLC & Tom Lange 1 Man Band a

It is great about valve amplifiers that they don't clip harshly. They are very well suited to music application. Never intrusive about their overdrive characteristics unless deliberately designed to give distortion, or poorly designed ;)

Teria o esquema amigo

Have you ever thought about building a 813 linear amplifier? 🤔

@ElPasoTubeAmps

11 ай бұрын

It is on my mind all the time to build with the 813. I have recently converted a linear amplifier (class-B) SSB amplifier to a grounded grid (GG) and plate modulated it for AM. It runs a single 3-400Z and I plate modulate it with a pair of 3-400Z in a class-B modulator. Works great. Until I started this project, I was unaware of the GG, plate modulated, Class-C configuration. It is actually very common but not for amateur radio operators because so few run AM anymore. I do have several good 813's but haven't use them since this project 7 years ago. I am going to attend an auction this afternoon at 5:30 at K5WPH club here in El Paso. I hope I don't buy too much more junk... 🙂

@MM0IMC

11 ай бұрын

​​@@ElPasoTubeAmpsI'm planning to build a grounded grid linear amplifier based on a pair of Russian GU-13 tubes (equivalents to 813). I've never built an amplifier without a bias circuit before...

@ElPasoTubeAmps

11 ай бұрын

@@MM0IMC There are a several tubes that can be run with no negative bias as long as the plate voltage does not exceed some value. I don't know exactly what is for the 813 but I would guess 2500 volts - best check that first. The triodes like the 3-400Z, 3-500Z, and 3-1000Z are know as "zero-bias" triodes and can be run as high as 3500 volts with no bias. The same is true of the 4-125A, 4-250 and 4-400A and the 4-1000A if the grid and screen are all grounded they operate as zero-bias triodes and need no bias supply. Even the 811A can be run with no bias as long as the plate voltage does not exceed 1250V (I think that is the correct plate voltage...) but the 4-65A can not be run as a zero bias tube. Grounded grid (GG) amplifiers are easy to build and stable and require no neutralization and only a plate supply - and filament, of course. The 813 is a beautiful tube. I know there are several Russian tubes that people use but I have never had any. I am sure they are very good. Good luck with your project. 73 Stay Safe

@MM0IMC

11 ай бұрын

​@@ElPasoTubeAmpsI've built 3 linear amplifiers over the last two and a half years. One has a Russian GS-35b triode in it and the other two have a single GI-7B triode in them. All are grounded grid.

If only you lived near moline illinois, I got Magnepan Tympani's that'll eat up those watts

@ElPasoTubeAmps

8 жыл бұрын

I would love to use this amp in a live venue and I would need your speakers but I doubt it will ever happen. I believe it would perform very well in the vocal and lead guitar/instrumentation category but not so much so as a bass amplifier.

@intothevoid9831

8 жыл бұрын

Well the magnepans are just super inefficient loudspeakers, apparently the Tympani's sound very good with Audio Research pieces.

If you were near by I would let you try it on my cabs they are switchable 2/4/8 ohm 1.5 kilowatt twin 18 inch / 46 cm I run these on a pare of 4-1000 amps each amp has 2 opt push pool 12DQ6 driver 12MD8 driving the 12DQ6 and a first stage 12BE6 gane control from 200 mv to 10 volts these amps will do 1.45 kilowatt @ 4% 45 HZ great for shows

@ElPasoTubeAmps

8 жыл бұрын

Hi Jamie - I wish I could try this amp on our speakers also. Wow... 4-1000A amps. That is bigger than anything I have built. I did build one bigger than this one and it is the 3-400Z amp where I could get 1.3 KW. Here is the KZread link. kzread.info/dash/bejne/nGZktauthbG8qZc.html I ended up changing the 3-400Z amp to this 813 amp as the bigger amp needed almost 30A of current at 120 volts. The 813 amp runs nicely on a standard US 15 A circuit.

hi sir i saw your video i know you are professional person ....sir i want make circuit with 6528 vacuum tube...but i need to otl schematic..please lead me if you have a good circuit...if you need my gmail...you just say to me after that i will send it for you..thankyou

@ElPasoTubeAmps

2 жыл бұрын

OTL amplifiers are something I have looked at a number of times but never got around to building one. I am not familiar with any particular schematics so I don't know any one to suggest. However, the 6528 is a low mu triode used in series regulated power supplies with the most common tube being the 6080/6AS7 so I would suggest searching the Internet for 6AS7 OTL amplifier schematics. Here is a link to lots of schematics and ideas. Best of luck with your project. www.google.com/search?q=6AS7+OTL+amplifier+schematic&rlz=1C1CHBF_enUS839US839&sxsrf=AOaemvJmcxOYBT0p3avzFGz_3Qrpiwlelg%3A1642224813339&ei=rVziYc-ZFLfKkPIPmYWDwAU&ved=0ahUKEwiPpI-VhLP1AhU3JUQIHZnCAFgQ4dUDCA4&uact=5&oq=6AS7+OTL+amplifier+schematic&gs_lcp=Cgdnd3Mtd2l6EAMyBQgAEM0CMgUIABDNAjoGCAAQBxAeSgQIQRgASgQIRhgAUABYywxgtQ5oAHAAeACAAb0CiAHrBpIBBzAuMy4wLjGYAQCgAQHAAQE&sclient=gws-wiz

Kha sa malaga

Now you can try a 1360W audio amp! kzread.info/dash/bejne/nGZktauthbG8qZc.html

I don't know what I'm looking at. A Fusion core for a space ship? Mightiest Dildo ever? I don't know.

@tm80notgoodwithnames58

8 жыл бұрын

audio amplifier

Это звук.

For someone who is interested in sound....why the hell is your audio so noisy?????

Horrible sinusoid!

That's bad ass dude'