6C33C Monster Tube Amp Build: Finalizing this Build!
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- čas přidán 6. 09. 2024
- Well after some more reflection, I think I'm going with a cathode bias version. In this video we draw up some load lines for the output tube, pick the bias point and calculate up the parts to get us there and power the heaters!
Warning DO NOT START BUYING PARTS! Other than maybe the 600 ohm output transformers, the build is likely to change!
In this video series I want to start by showing my thought processes as I take a schematic from an online download to a working amp using parts that are readily available to me. Sometimes a design is done in a different part of the world or in a different time and parts need to be adapted to work.
Here is the design software I used in the video:
www.duncanamps...
The original article can be found here:
www.dhtrob.com...
You can send me links and messaged at:
www.skunkiedes...
I have a new personal email: stephe@skunkiedesigns.com
Here is my Patreon, as well as the donation page at my site, if you feel so inclined to help fund some of the future projects for the channel!
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Running One filament /cathode will prevent ypu a lot off problems !
One of these is runawsay and redplating ........( always a risk with shared cathode bias )
Also avoiding heat problems essentially on the socket ........
DHT Rob ( Durch) made great amplifier designs at that time and used always quality components...also shared good advice and his personal experience .
For the fun and history ...........When a soviet pilot defected to the west and landed his MIG25 in Japan , the CIA examined the latest soviet secret weapon and they were asthonihed that this modern plane still used the ( old) tube techology .....Baby on board , NO but the 6C33 tube etc on board !....some started laughing because the USAF used already SS and computers on their fighter planes...............until someone made a the following comment...
" In case of a nuclear exchange all tour own planes will fall out of the sky but NOT the Russians !"
EMP would benefit from the protection inheren from the technology of tube techology to withstand and survive an EMP ...........
That's good news for us with our tube ampliers also ..........We will still be able to listen to our favourid and beloved music...........
Kind regards
Damn, Frank. 😊🎶 Thank you very much for that fantastic comment. I’ve absorbed so much great information from you over the past few years.
I’ve got a question for you, if you don’t mind. Is it possible or have you ever heard of an amplifier design that uses a dual triode power tube that was run as a push pull circuit, assuming the 2 sides are matched, using a single power tube? Would the 2 sides drift rather quickly? I know it’s often done with 12AX7’s and similar tubes but in parallel or 2 closely matched sides in certain designs. It makes sense in my mind and in theory, but I’ve got a feeling there’s likely a reason it won’t work. (now, I’ve got the Beatles tune, “I’ve got a feeling” stuck in my head….lol)
Stephe, I used DHTRob's schematic with the 6C45Pi, I had a power transformer 506VCT and fullwave tube rectifier 6D22C. Instead of a plate choke I use a 15W/230V bulb and for the cathode resistor (6C33C) also a bulb, 75W/230V.
This amp will be a beast. That is a lot of iron!
Yeah, I'm glad it's not a stereo unit :P
I got excited and went to PSUDII because I've been using it to optimise the power supply on my tube amp. You could pick the 6H 159R 200ma 150ohm choke, which is the same size and weight as the 4H 159S. Then you can choose cap values of 33uf for C1 and 230uf for C2 to get a 250V B+ supply. There is an audible downside from picking a large first cap - it slows down the power supply. I am enjoying a noticeable difference in clarity shifting from C1/C2 cap values of 108uf/108uf to 58uf/216uf.
YES , indeed ...............big is always ( audiophile talk) better is a most common mistake when designing a PS.....correct values do alway sound better and stressless ........many also missuse the Duncan tool .....one must take all the circuit design and secondary currents into the account....
Overshoot and oscillation is a common fault even seen on a lot of commercial designed amplifiers from some respected brands.......the latter wil lbe triggerd at every dynamic current demand ..........and what is Music besides transients and it's harmonics...!! .....it is definilly NOT a sinewave nor a square wave ...
Have a nice day ..
@@frankgeeraerts6243 - agreed! Slow and with overshoot and ringing - a trio of horrors! The 33uf/230uf values for C1 and C2 don't appear to have any of this and would keep ripple under 65mV. However, you are right that more information about the rest of the power supply and load will is necessary to dial-in final values. Coincidentally, the schematic chosen here is DHTRob's and it is his material on power supplies using PSUDII that I've followed.
Good points. I've normally used smaller first caps being limited by a tube rectifier, I'll check out what you are saying as that makes sense.
@@Luckiestmanalive-bb1mi Yes and you can hear it trough the ease , the tempo and absence off any stress......understanding music and liking music that otherwise seemed to be not so enjoyable but when the power supply is well designed ...you do listen and enjoy .
@@SkunkieDesignsElectronics IN fact you're doing it already by using the limited value and the good quality of the Solen cap at the input .............your ears told you already this sounded good ....
I used to read my dad's Radio electronics back from the late 40s after ww11 they had articles about to use them RF tubes from the JAN. Anyway I remember a single ended amp using a 826 similar tube for audio. The old books had some good ideas. Anyway. Keep safe Amps have lethal voltages🤬🌹❤️
Fixed bias ...versus autobias ( cathode bias ).....
As designed by some maufacturers ( Luxman and others ).............You can build as hybrid bias , this ia partly a cathode bias and fine tuning the current with a fixed bias .....this works realy well and sounds good as well as give some kind of protection to the tube..
Interesting idea! I may try that on the 4E27 build.
I had the same idea, just perhaps doing it the other way, with fixed bias and adding a smaller cathode resistor for stability purpose, thus avoiding a large power dissipation there. But then you probably would need to drop the B+ and possibly using a different power transformer.
This is the struggle I was having, trying to get the plate voltage low enough, with enough ma without resorting to custom wound iron.
@@SkunkieDesignsElectronics
You are an inspiration for DIY and all newbies wanting to buils something .
themselves ......often better than many amplifiers they can buy on the international market .
Teaching how to solve problems and displace commercial barriers as well as solutions by sharing your own learning proces and experience ..
As said once by Edison : " 90 % of thinking and 10% to do it " one has to think before and ask the right questions !
Thank you the upload of such an interestinf project , the 6C33 is such an intersting tube , quite different beastto tame .....
Most comercila 6C33 amplifier finish by having need service and face reliability problems ..........using only one triode by using only one filament wil avoid a lot of problems , in fact this tube is an aberations because it is erssential a double triode wit a shared anode.........the inverse of two triodes with a shared cathode , both habve similar problems .
the low transformer ration due to it's low impedance ......will be a benefit for quality audio transformation ........as long as the OPT can handle the currents ..;
Wish you al the best with this amplifier project and very interested in it's birthday to come ...
I was thinking to fine tune the B+, instead of using a big and costly choke for that you could add a simple R C section. Tuning the voltage drop with a simple resistor. Much more inexpensive and easy to tune to get your desired B+. An RC section also helps in filtering the ripple, just not as much as with a choke. So basically if you need less ripple , add another choke, if you need to drop voltage add a resistor.
If you are using half of 6s33s you can use 6s41s tube because its half of 6s33s
Well I already have these sitting here :) I've read the 1/2 of a 6C33C also sounds better than this other tube.
Very good brain work
This is _the best_ tube audio channel!
Moin,
There's a reason for the two cathodes.... If you only using one for having easier circuitry you end up with a overheating cathode, which will dramatically drop service hours of your tube.
But you using the tube all 'illegal' anyway....
There's a quote in the datasheet which says: if you running onr cathode only or 200 volts you need to derate the tube...
Also it needs a rather low impedance driveing stage, any decoupling cap in series with the driver causes instability of it.. And make the output tube goes into oscillation. Either do a direct coupling or a cathode follower as a driver to have a real, low driver output impedance.
Trust me, I built a real monster amp using six (that's 6) 6c33c tubes in pushpull at 200volts and both cathodes lathodes. Delivering around 350watts clean (0.5% THD at maximum output 30hz up to 18khz) sind an Ei 130 magnetic core size output tranny (around 15kg/30lbs of core weight alone)
Driver section is 6sn7 followed by a phase splitter 6sn7 and another 6sn7 with both sections in parallel - one for the high driver and another one for the low side of the pp configuration. In order to prevent RF ringing at maximum output.
Because the 6c33c has a rather high control grid capacity which need a fair amount of current at large swings even if the tube itself is still in class A. If you try real A2 mode (with positive control grid voltage) the control grid needs several milliAmps of driving current... And if your driver can't handle it, it will go ringing, because the control grid isn't fully controlled by the driver section and go into oscillation due to the large anode/grid capacity all by itself.
Good luck.
Data sheet shows curves for one cathode so clearly it was designed to use one if desired and I am derating the tube. I haven't even started and I already have someone saying what is a small tweak to a known working design won't work... Where did I say I was going to run positive grid voltage?
@garagepunkfan
0 seconds ago
I still maintain that Dave Gillespie's EFB biasing scheme is ideal for this tube. It's the pathway to more output wattage and less THD, using less power, than cathode bias, without the instability that this tube displays running fixed bias. The tube always stays in it's optimum operating condition, with the bias voltage always tracking a perfectly inverse relationship to B+ voltage as it rises and falls with sag. All this is done with $10.00 worth of parts
Go for it! Love to see your build using this.
Stephe: I'm excited to follow along with this new monoblock amp design process. One suggestion...how about mounting that ugly cathode bias resistor inside the chassis, but with vents in the top of the chassis? The vent holes or a vent grill of some type could be more aestheticly pleasing than an ugly ceramic resistor on top of the chassis IMHO, but still dissipate the heat.
I'm not using ceramic resistors.
@@SkunkieDesignsElectronics Same suggestion applies to any resistor...
I personally don't think those aluminum body resistors are ugly, but some folks think all my amps are ugly! That's why DIY is so great, you can build your amp how ever you like!
@@SkunkieDesignsElectronics Point taken. Tube amps are a design challenge in general with all the large transformers and chokes and such. The glowing tubes are the part we want to see!
Really? I think they are really nice. You go all out with the tube rings and the nice round power buttons. Everything seems to be carefully laid out. Your mono blocks have the nice wood sides. I guess they are comparing them to a commercially made amp, like a Manly, or McIntosh that has the potted transformers. But that stuff is big bucks. I would rather have an amp that performs well than looks really pretty.
Lotsa iron phew! Looks a bit cramped but as long as it sounds good! A big ole SE amp I'm betting it will! Lotsa sweet even harmonics. Not so many odd harmonics!😊
Yeah it will me pretty tigh., I hate to go to the next size up 3 inch thick chassis, but if you have the room for that size footprint, you could do that.
As pentode you could use an EL86 / 6CW5 ? Those are used to drive some power tubes
Perhaps to high voltage needed ? I think it is around 280 V
24:00 Chassis is looking pretty "busy" with all that iron. It also has me wondering what the weight is going to be. Definitely curious about the cost. Looking good so far!
It's gonna be heavy and it's not going to be cheap lol. If you're looking for a low budget amp, don't build something with these tubes!
@@SkunkieDesignsElectronics Oh no, I am definitely not going to build these. I am coming along for the ride though because I am interested and curious in the project. One thought that did come to mind to cut down on the iron and take things in a different direction in terms of a two chassis design. Have the output transformers and plate chokes with the tubes in one chassis, and have the power supply in another.
By far the largest iron is the output transformers!
Have you considered the Hammond 1626SEA audio output transformer for this project? Or is it too expensive comparted to the Edcor?
I'm sure they will work fine, I just have the edcor already.
Name it "Big Iron."
Hi Stephe! If you need to shave off B+ but don’t really need more filtering what are the benefits of using chokes over large resistors or even a voltage divider? Thanks! Looking forward to this build series!
An RC can work to drop some voltage (I did this in my production EL34), I just figure if I have room and the B+ is a little dirty still, why not add another choke? That part of the build is still up in the air :)
voltage divider at the needed plate current will result in dropping resistors of substance taking up space & producing heat. Multiple RC filters can accrue substantial ripple filtering with gapped magnetics' stray flux leakage and probably cost less than chokes, but this is already a choke-destination design, with satisfactory results in for the designer in previous designs.
wow the chassis is small looks nice
More like the iron is big :P
Just came across this, read the DHRob article, it’s not in there - can anyone tell me what its output is?
I have no idea yet, I'm going to guess 10-12W?
hi will you add more videos on this build?
Working on it this week! Got sidetracked :)
Hi Stephe. I’ve seen some awesome metal “tube rings” on your builds where the tubes extend out of your chassis. Are those custom machined? If not, where can I buy some? Thanks in advance!
youdaelectronics.com/
And then search "Ring"
@@SkunkieDesignsElectronics Thank you, Stephe!
Can't you mount the choke on the vertical side of the chassis you have?
It won't fit sideways either.
@SkunkieDesignsElectronics sorry I guess I didn't expect a response, the choke looked taller than wide? You're doing amazing stuff opening up valve/toob amps design build to the wider community though...respect due
please, could you be so kind and give us, the people in europe with 220/230 volts on electric grid, some ideas on power transformer. thank you in advance
This >IS< a 220-240V compatible power transformer...
"Primary: Universal - 100, 110, 120, 200, 220,230, 240 VAC 50/60 Hz."
www.hammfg.com/electronics/transformers/classic/300?referer=787
Hi, buy a 200-300VA isolation tranny (torrid core) and rewind the secondary. for 130volts AC which let you have around 200 volts DC (fullbrigde rectifier) for the anode voltage. These come rather cheap compared to custom wound trannies for tube amps.
I build this amp and sound good but nothing special in SE.
So you built my amp exactly like I'm in the future planning too? Can you share my schematic I haven't drawn yet with me to save me some time?
@@SkunkieDesignsElectronics This is not your amp.On Russian forum you can get many schematic with this tube:)
Well there are 300B amps that sound "nothing special" and other that sound spectacular. It all depends on how they are build and designed, more so IMHO than the tube used.
@@SkunkieDesignsElectronics Maby 30 or 50 years ago not today.
Stupid oot question, can I use OTL for Headphone amp ? What impedance is best ? 120 ohm ? 300 ?