Пікірлер

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  @myrcflyer9999Ай бұрын

  Any plans for an optimize single tube 845 SET? in the future. Something that can put out around 15 to 20+ watts with low or no global feedback and ultra low distortion ie 0.1 or less in the 0.1 to 2 watt output?

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  @bandwidthaudio7479Ай бұрын

  Not at this time. The parallel output stage is part of the magic for this amps exceptional open loop performance. As output power increases, output impedance must fall such that the “quality” of the power remains high. In other words, as power increases, speaker control becomes increasingly important. The parallel output stage gives a significant reduction in output impedance when combined with our output transformer. It also reduces noise since the 845 filaments noise can be wired to cancel eachother. We discuss this in detail on the website. Thanks!

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  @reserva120Ай бұрын

  Are these the same Desgin “ look “ of the cavers ??

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  @bandwidthaudio7479Ай бұрын

  These are our own design for both the circuit and chassis design. The chassis look loosely based on our 288 and 22A3 amplifiers, but all the component placement and design was optimized to keep the power supply away from the signal paths. see www.bandwidthaudio.com

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  @5thlevelweb8872 ай бұрын

  How does this do with Martin Logan electrostats?

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  @bandwidthaudio7479Ай бұрын

  These amplifiers will likely work very nicely. I know some electrostatic speakers have low impedance at high frequency due to the capacitance of the panel. How low the impedance gets should be verified. The parallel output stage will help a lot when the speaker impedance falls compared to other SET amps. The parallel output stage would be a requirement in my mind for a speaker if this type if an open loop amplifier is desired.

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  @5thlevelweb887Ай бұрын

  @@bandwidthaudio7479 thanks for the info. I believe these drop down to 1.7r at 20k.

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  @BoKo1402 ай бұрын

  Awesome! Gonna go for lottery ticket now!

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  @michaelcorlet29982 ай бұрын

  50watts.more like 30 at 10% distortion.

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  @bandwidthaudio74792 ай бұрын

  Actually this amp does a full 50W at 2.75% open loop. We measure the performance real time if you made it through the video.

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  @TheCharlesAtoz2 ай бұрын

  I am new here- do you get tubes from other countries?

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  @dmark26392 ай бұрын

  Amazing! I will check out your website. Are you winding your own transformers or sourcing them from somewhere?

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  @arierol25182 ай бұрын

  Nice amps,just a itteration from the Ankoru2 from Andy Grove's Audionote.They have a other tube setup with 300b to swing the 845.Are they also idele at 500watts?But congratz on the build,1250v is no joke to play with.

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  @bandwidthaudio74792 ай бұрын

  Thank you!. I would argue that the 2845 are quite different from the Ankoru2. Yes both use a pair of 845, but the internal design approach is quite different. If your interested, see our other videos. I also noticed that the Ankoru2 is very light on specs. We show complete specifications on our site. Our 100dB SNR open loop on an amplifier like this is no joke! Cheers!

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  @KB-os6lh2 ай бұрын

  Stunning! Cheers from Australia.

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  @kenhiett52662 ай бұрын

  I'm new to tube amps. Will someone please explain how the noise coming from the 845s when he bumped it up to 50 watts isn't a problem? Is it because the volume coming from those tubes will always be drowned out relative to your speaker output, even with the quick dynamic swings in classical music?

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  @klaymoon12 ай бұрын

  Congratulations!! Looks amazing!! Even better than I had imagined. I will be ordering it as soon as my fund is available.

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  @bandwidthaudio74792 ай бұрын

  Thank you! Hard to get a sense on camera, but they look even better in person. I hope you do get to experience these in the future. We’ve never heard any amplifier that sounds as good as these.

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  @klaymoon12 ай бұрын

  @@bandwidthaudio7479 I trust you! With all your passion into it, I’m sure it is a masterpiece. I will be liquidating a whole lot of gears for it. :)

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  @paulb46612 ай бұрын

  Words fail me Gentlemen- this is simply a spectacular piece of kit and a tremendous achievement! Performance and looks to die for, this is definitely one of the best, if not the most accomplished amp of its kind ever made! Even if it turns out to be out of reach for most of us, it is still worth every penny. Congratulations! It's beautiful.

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  @bandwidthaudio74792 ай бұрын

  Thank you! Really glad to see that our hard work is appreciated! Anyone lucky enough to have a pair of these will be extremely happy.

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  @coldfinger459sub04 ай бұрын

  The arcing on startup on rectifiers this problem was covered by Mr. Carlson labs and he made a fix for that many years ago.

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  @neccron99564 ай бұрын

  You mention the disadvantageous of toroidal transformers, but what about R-core transformers?

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  @drdyna4 ай бұрын

  Man, I would love to build 845 monos, I'm so jealous! lol. I wish I could afford the iron.

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  @mfr586 ай бұрын

  Yes, as you are finding, quality control is one of the most expensive parts of manufacture.....

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  @300poundbassman6 ай бұрын

  Beautiful chassis ,we have had mains voltages go from 110 to 127. Used to be 125 Ll the time. Now it's anyone's guess. I try and put good quality inrush limiters in anything that I work on. Specially older sets. . nice color on that chassis,any schematics available? Just curious. Thank you 😎

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  @prattacaster8 ай бұрын

  The 470k on the upper triode is less about signal and more about allowing the grid to have a dc reference for bias. Its a grid leak bias stage.

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  @sallyhamly-anderson81299 ай бұрын

  I have a working 1700. Interested?

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  @Satchmoeddie10 ай бұрын

  All Hickocks I own are safety interlocked so it's pretty difficult to screw one up. I think most Hickock testers share the same switches between a lot of models. I prefer my Triplett 3444A over most suitcase testers. I have the Hickock adapter for Magnoval, and Duodecal Compactra and for 10 pin Decar tube bases. I think it also does the Nuvistor sockets too. The Weston 686, Hickock 700 and the big RCA lab tester + the old ICC testers will go up to 300 volts anode, so testing 300Bs is not a problem. Avo testers can run up to 400 volts anode which is really nice!!! Regulating anode, G2 (screen), G3 (beam former), G1 control grid, and AC or DC heater voltages is very easy with hi volt MOSFETs VR tubes and maybe Zener references. AC heater voltage is done with a small 2.5 amp double regulated Variac now. The 120 in is regulated and the output has feedback on it now that makes very slight adjustments with a pair of matched & heat coupled MOSFETs. With the 120 in regulated there is not very much to regulate coming out. I have used my big 20 amp Variacs on burn in tables. I am not measuring with those. The GR real Variacs do not drop with a load either. Regulate the 120 in and let them cook. I converted a Tektronix 576 to plot curves with tubes, using a regulated power supply for the screens, and adding a heater supply. Make a test jig and that is pretty much all you need. The 576 is a tad underpowered to test tubes like 7027s, 8417s, 6550s, KT88, EL156s, etc. at full power. You can run them at 70% and then ramp them up for a quick curve family plot, and then let the machine rest for a while. Even 6L6GCs are close to the edge for a 576. Don't waste your time with the 577. It's way too underpowered. The 371Bs will handle 800 watts, 1500 watts intermittent, but they are $25,000.

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  @RRickenbacker10 ай бұрын

  Great video. Thanks!

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  @klaymoon111 ай бұрын

  The parts and design looks TOP NOTCH!!! I'm still waiting for this amp. :)

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  @bandwidthaudio747911 ай бұрын

  Thank you!! Don’t worry, this will be done soon and available for special order. Turning everything into a production ready product is always a variable. We are working on final wood sides which includes templates for production and bucks for our sheet metal vendor.

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  @klaymoon111 ай бұрын

  @@bandwidthaudio7479 Great to hear! Hope the launch will be as smooth as possible!

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  @klaymoon111 ай бұрын

  Just checking if there is an update on 2845 amp. Because I think this will be an amazing amp.

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  @GavinHodgson11 ай бұрын

  Beautiful work

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  @tee-jaythestereo-bargainph2120 Жыл бұрын

  Dam impressive !

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  @sonusancti Жыл бұрын

  Apart from speaker sensitivity, impedance behavior is also influential in ease/difficulty of driveability. Staying above 6 ohms would be ideal and can compensate for a lesser sensitivity number. Audio is complex.

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  @Tysman909 Жыл бұрын

  Wonder how would compare to the very accurate hickok 539C

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  @ARASHMAFI1 Жыл бұрын

  Which AP hardware are you using for your tests ?

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  @alaingingras7224 Жыл бұрын

  What do you use as current/distortion program?

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  @frankgeeraerts6243 Жыл бұрын

  I agree scaring with many ( often asian ) amplifiers .........most audiophiles have no clue about tube technology but buy those ..............nor transformers. thanks for the upload !

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  @derrick_builds Жыл бұрын

  Sharp design. Looks great.

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  @bandwidthaudio7479 Жыл бұрын

  Thank you!

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  @munja2111 Жыл бұрын

  I am so happy that i found this channel, great work man.

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  @CraigHollabaugh Жыл бұрын

  Great insights into EI/Toroid comparison and high voltage build aspects. Thanks from Colorado.

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  @paulpaulzadeh6172 Жыл бұрын

  What about buzzing in those transformer ? They buzz with signal music

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  @jkjome4095 Жыл бұрын

  This looks like a wonderful amplifier. Are you thinking of offering a build series and circuit schematic for DIY'ers, like you are currently doing with the 40w amplifier?

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  @eugenepohjola258 Жыл бұрын

  Howdy. Credits to Bandwidth Audio. I really liked the presentation of the EI power transformers. The unavoidable air gaps aspect was new to me. Yes. They fight saturation. I would assume toroid manufacturers test their prototypes with clean 50 or 60 Hz and determine the windings close to saturation. There will be little room for residual DC in the mains. Thanks for the illumination. Regards.

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  @bandwidthaudio7479 Жыл бұрын

  Thanks for your comment! Glad it was informative.

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  @paulb4661 Жыл бұрын

  To call this methodical approach and resulting arrangement "Impressive" would be an understatement of the year.

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  @bandwidthaudio7479 Жыл бұрын

  Thank you! Glad all the effort shows through and these videos.

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  @2Worlds_and_InBetween Жыл бұрын

  yeah... nice work

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  @briandonaldson518 Жыл бұрын

  Nicely done on the specs of this OPT. About 15 years ago, I went through 4 iterations trying to make an OPT for a 833 DHT amp I was working on. If I lifted the ground between the in and out, it was a glorious 150 WPC, but the leakage capacitance put 1000 V on the speaker terminals. I think the laminations were about double the size you have.

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  @bandwidthaudio7479 Жыл бұрын

  That's a really big transformer! If only we could leave the secondary floating.... Out of curiosity, I actually have tried loosely holding the secondary at ground potential with a resistor to see if this reduces the effective bridging capacitance. This actually made things worse as the resistor added another pole in the transformer frequency response.

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  @briandonaldson518 Жыл бұрын

  @@bandwidthaudio7479 I can see that. The resistor dissipate energy while opposing the high frequency causing more rolloff that just the capacitance.

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  @Signal_Glow Жыл бұрын

  Are you writing about lifting the ground connection between OT's pri and sec? Why would you do that if things like galvanic isolation are the reasons for using OTs? I might not understand SE DHT amps because vast majority of my work is pro audio small signal stuff where OT's pri and sec grounds are always separated.

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  @briandonaldson518 Жыл бұрын

  @@Signal_Glow The OPT is a galvanic isolation, but it's main purpose is impedance matching and choke loading. IIRC, it's 5K to 8ohm. The ground is necessary for safety, because without it, the outputs floats to 1/2 B+, around 1000V. But the problem, grounding the speaker ground raises the leakage capacitance 4x, killing the top octave.

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  @Signal_Glow Жыл бұрын

  @@briandonaldson518 Ok, got it, grounded speaker/load. Similar to small signal circuits like mics, preamps, compressors.

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  @davidkclayton Жыл бұрын

  Nice work! What is your expected damping Factor? By the way where do you find capacitors that are negative tied to the case these days? I challenge you to actually test with an ohmmeter. This practice was abandoned capacitor manufacturers with the introduction of computer grade capacitors.

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  @bandwidthaudio7479 Жыл бұрын

  Correct, they are not tied directly to the case but the electrolyte that the capacitor jelly roll "swims in" is always contact with the case. This makes the case effectivity tied to the negative terminal and allows charge transfer to the case via the electrolyte. Exact damping factor will need to be measured but the output impedance should be around 1ohm on the 8 ohm tap without any feedback. FYI damping factor is often misused since the speaker voice coil DCR will dominate. i.e. even with an amplifier with 0ohms of output impedance, the speaker DCR (6-8ohms) will determine the damping of the moving mass (ie the speaker cone).

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  @mohinderkaur6671 Жыл бұрын

  Collins transmitter was driving a pair of 4-400a modulators from 2 6sj7 preamp tubes. and here we are. 845 and solid state plus el34

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  @mfr58 Жыл бұрын

  Wow, a herculean design! Of course you are generally correct in you discussion of toroidal vs EI transformers. However companies like Tent Labs and Toroidy make high quality toroidal, SE output transformers, so they must have some way of effectively gapping the cores to take the dc present......

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  @bandwidthaudio7479 Жыл бұрын

  Thanks you! I believe they use a ferrite or other core type made from a slurry of ferromagnetic and non-ferromagnetic materials (like ceramic). This reduces the effective permeability of the core and creates a "distributed" gapping effect. This is used all the time for power electronics. The problem with a power transformer is we want the permeability to be as large as possible to reduce core size. Gapping the core will reduce the effective permeability by at least one order of magnitude.

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  @mfr58 Жыл бұрын

  @@bandwidthaudio7479 Thanks for the explanation.

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  @tobyspencer1321 Жыл бұрын

  What type of MOSFET is used for the CCS?

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  @bandwidthaudio7479 Жыл бұрын

  These are IXYS depletion mode FETs

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  @careycraig4360 Жыл бұрын

  There is definitely a Learning curve to contend with I think but with regular use and repetition it would not be a problem. This unit is most certainly NOT your typical DRUG STORE Tube Tester of years ago!! It was a very well explained tour and functionality of this Hickok 700 Tube tester. It might actually be more correct to call this Machine a " Vacuum Tube ANALYZER ", as it is much more than just a Tester.

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  @bandwidthaudio7479 Жыл бұрын

  Yes, this is certainly a tube analyzer! You could measure datasheet curves with it if you are so inclined. Shame they are so rare! There is a learning curve, but the required repairs to get it operational forced me to learn the theory of the instrument. Now its easy!

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  @nehorayaudio Жыл бұрын

  Try to make it no negative feedback mu follower class A preamplifier It should sound amazing

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  @klaymoon1 Жыл бұрын

  That's a great looking THD graph! I'm eagerly waiting for the release of 2845.

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  @klaymoon1 Жыл бұрын

  That's a nice looking THD graph. Have you released this preamp yet?

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  @bandwidthaudio7479 Жыл бұрын

  This preamp is the font end of the PSET 2845 amp design. Not a standalone preamp in itself. It ultimately drives over 400V P-P into the grids of the 845 tubes as you will soon see in the video series. I think that may fry a normal RCA cable and whatever is connected to it😜

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  @klaymoon1 Жыл бұрын

  @@bandwidthaudio7479 Looking forward for your new 2845!

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  @Signal_Glow Жыл бұрын

  Yes, explanation is very good, THD+N and THD vs f are very revealing. I'm making microphone preamp with 2 mu follower stages. Mu followers are not seen that often in pro audio designs despite having very good specifications like THD so low they don't need NFB, driving capabilities are not that far from SRPP, high gain, etc. It needs 1:10 input transformer, output will drive loads as low as several k ohm, 2:1 output transformer takes 6dB of gain but then drives 600r to very high levels. Circuit consists of 2 E88CC tubes, one for each stage with pot between them for level control, gain is very high at 70dB or 76dB without the output transformer. One stage made from low mu tube would make nice hi-fi line stage, variation of the circuit will make different pro audio devices like active DI, passive summing gain make up amp, line amps for passive eq's, etc.

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  @klaymoon1 Жыл бұрын

  Great looking amp there! Is 288 Monos your answers for the 40 watt amp? Do you have any sound demo on your channel? Sure, no one can really hear anything on KZread. But, when people are using the same headphones, at least we can hear the relative differences in the tonal quality, PRaT, bass quantity, etc.

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  @bandwidthaudio7479 Жыл бұрын

  Thanks for your comments! The 288 are our 60W mono P-P amps with a pair of KT88 output tubes. The 288's were our first product and still going strong! This new 40W (more like 50W) amp is based around a PSET pair of 845 tubes hence the 2845. Check out the other videos to learn more. Development has been slow be we are nearing the end and close to have a production ready 2845. These will be monsters!

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  @klaymoon1 Жыл бұрын

  @@bandwidthaudio7479 I will be looking forward for the release of 2845 and start to save money for it. 😄

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  @malcolmfairleigh1193 Жыл бұрын

  one of those tubes is labelled 6BL7

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  @myrcflyer9999 Жыл бұрын

  Hi, curious about the o/p transformers. Are these going to be EI cores or C cores?

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  @bandwidthaudio7479 Жыл бұрын

  These will be EI core. With a air gapped transformers for single ended tube amps, the the core performance (permeability) is reduced dramatically (around a factor of 10) with the gap to prevent core saturation due to the primary current flowing to bias the output tubes. A higher performance C core is unnecessary and expensive since its higher core performance requires a larger gap to reduce the effective permeability back to the required/target to handle the DC current.. In addition, a larger gap allows for a larger reign for leakage flux out of the core and thus higher leakage inductance. Some assume that C cores are better but it is truly application specific. Also, the natural gapping caused by EI laminations has some built in "distributed" gapping effect that allows for a smaller air gap than typically calculated. As far as core hysteresis goes, the gap also helps linearize and flatten the hysteresis BH curve by the same ratio as the reduction in the effective permeability. So a big EI transfomer that is gapped can have very good distortion performance and very flat inductance curve vs signal level. Hope this makes some sense!

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  @myrcflyer9999 Жыл бұрын

  @@bandwidthaudio7479 Thanks for the explanation. Following the development with great interest.

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  @ericschulze5641 Жыл бұрын

  Now make the same tester digital, & it will take twice as long & you'll constantly be wondering if your readings are accurate,