try www.rfparts.com They are in California. If you want a really bulletproof tube get the graphite plate 833C. These only cost about $120.00 ea US last time I checked. A super bargain for such a powerful triode IMO. I am referring to their Taylor house brand made in China. Good quality tube. I've seen them used in industrial RF induction heating equipment and know that they really take a lot of punishment where a standard tantalum plate US made 833A (much more expensive too) will literally melt a hole in the plate.
833 availability
Hello ,
i finished my 833-amp half a year ago. so i needed these triodes as well.
I bought:
- GU-48 form Russia. $ 65 a piece
- Amperex 833A. € 100 a piece
- Penta 833C. $ 96 a piece
- Tungsram OT400. € 82.50 a piece
I don't know what you're looking for. There is a lot of difference between the items. Not only sound-wise, but certainly build quality !
And of course you have to take into consideration the postage to Canada.
Audio-wise:
- The GU-48. Bass-performer. Not very smooth in the highs !. Incredible sturdy built. Pins will not fit correct to standard Johnson sockets.
- Amperex 833A. Solid perfomer. Well built. Very good sound-wise. Also on the frequency extremes.
- Penta 833C. A tad more bass and a bit less in the highs than the amperex. Not better or worse......just different. Extremely fragile ! Yes, they can take a hammering in a circuit with the very respectable plate dissipation. But on transport.......
- Tungsram OT400. Same as the Amperex and the Westinghouse and the RCA i have already at my home. Pricewise unbeatable.
You need 4 x 833 ? Push-pull ?
Happy building.
Reinout
(included a picture of one channel 833-amp (up) with external powersupply (down)
Hello ,
i finished my 833-amp half a year ago. so i needed these triodes as well.
I bought:
- GU-48 form Russia. $ 65 a piece
- Amperex 833A. € 100 a piece
- Penta 833C. $ 96 a piece
- Tungsram OT400. € 82.50 a piece
I don't know what you're looking for. There is a lot of difference between the items. Not only sound-wise, but certainly build quality !
And of course you have to take into consideration the postage to Canada.
Audio-wise:
- The GU-48. Bass-performer. Not very smooth in the highs !. Incredible sturdy built. Pins will not fit correct to standard Johnson sockets.
- Amperex 833A. Solid perfomer. Well built. Very good sound-wise. Also on the frequency extremes.
- Penta 833C. A tad more bass and a bit less in the highs than the amperex. Not better or worse......just different. Extremely fragile ! Yes, they can take a hammering in a circuit with the very respectable plate dissipation. But on transport.......
- Tungsram OT400. Same as the Amperex and the Westinghouse and the RCA i have already at my home. Pricewise unbeatable.
You need 4 x 833 ? Push-pull ?
Happy building.
Reinout
(included a picture of one channel 833-amp (up) with external powersupply (down)
Attachments
tube adresses
Hi again Etalon90,
forgot the tube-adresses. Sorry.
Here they are:
- www.tubes.ru for the GU-48. Based in St Petersburg, Russia.
- www.pentalabs.com for the 833C. USA (but they are Chinese tubes)
- http://tubes.halfin.com or they sales-manager michael@halfin.com for the Tungsram OT400. Brussel-based (Belgium).
I saw that one of the replies spoke about a $ 120 tube from Penta. I suppose it will be the 833D (for $ 126). Remember that the filament requirements for that tube are different than from the standard 833A/C !
with regards,
Reinout
Hi again Etalon90,
forgot the tube-adresses. Sorry.
Here they are:
- www.tubes.ru for the GU-48. Based in St Petersburg, Russia.
- www.pentalabs.com for the 833C. USA (but they are Chinese tubes)
- http://tubes.halfin.com or they sales-manager michael@halfin.com for the Tungsram OT400. Brussel-based (Belgium).
I saw that one of the replies spoke about a $ 120 tube from Penta. I suppose it will be the 833D (for $ 126). Remember that the filament requirements for that tube are different than from the standard 833A/C !
with regards,
Reinout
Attachments
unprotected ?
Hello RCAVictim,
unprotected ?
Normally i use the amps without the add-on cover. But when friends arrive that do NOT know that a tube can be hot-and-dangerous i'll put the covers on.
Same when there are children around. The holes in the cover are large enough to let the heat out, but small enough to withstand poking fingers......
But yes....i'm into tubes and these 833's are normally unprotected.
What kind of tubes/amps are you using ?
Reinout
Hello RCAVictim,
unprotected ?
Normally i use the amps without the add-on cover. But when friends arrive that do NOT know that a tube can be hot-and-dangerous i'll put the covers on.
Same when there are children around. The holes in the cover are large enough to let the heat out, but small enough to withstand poking fingers......
But yes....i'm into tubes and these 833's are normally unprotected.
What kind of tubes/amps are you using ?
Reinout
Attachments
For the GU-48
A better source would be gstubes. Their website is http://www.gstube.com/tubes/
They are slightly more expensive than tubes.ru but shipping is often much cheaper. I was qoute a shipping cost of 15usd to ship from Russia to Malaysia for a pair.
Reinout
I have been trying to contact you thru email, gues the email did not go thru. ANy progress on DAC. I manage to score a pair of Johnson 833a fillament sockets. So now will begin to order the tubes soon
A better source would be gstubes. Their website is http://www.gstube.com/tubes/
They are slightly more expensive than tubes.ru but shipping is often much cheaper. I was qoute a shipping cost of 15usd to ship from Russia to Malaysia for a pair.
Reinout
I have been trying to contact you thru email, gues the email did not go thru. ANy progress on DAC. I manage to score a pair of Johnson 833a fillament sockets. So now will begin to order the tubes soon
NickC said:
Did you get the kind of porcelain feed through sockets that bolt through a vertical metal panel and suspend the 833A in front of the panel? They have knurled thumbscrews to tighten the clamps to the tube pins. These are hard to find and expensive when you do. I have a pair of those old originals salvaged one each from two 10 kW RCA broadcast transmitters. I could mount them through a mirrored panel. It would look like there were four tubes in the amp. Pretty I think. I may do something crazy like make an 833A SET stereo power amp someday when I get my other projects finished. I have the 833A tubes in stock. I have a 300B driven 805 SET amp now so it won't be because I need it.
I'd be torn between the 833A and the Eimac 450TH as the Eimac looks considerably more impressive IMO. I have those also. Here is a picture of both. You judge.
Attachments
Re: unprotected ?
I've got two darling house cats (children) so I have to be careful not to have anything potentially dangerous out in the open even if I'm right there. My amp in the system upstairs currently is a pair of HF-20 Eicos (P-P 6L6's) with some DIY mods. Those are perfectly safe with no top cages/covers IMO as there are no tube plate caps or exposed circuits at all.
Downstairs on my more serious system I have a MC3008AB Ming-Da which has been extensively modified by myself. It uses 300B's to cathode drive 805's in SET. Part of my mods was to make the tube cover well interlocked so the amp cannot function with the tube cage off. I know that I will die someday, probably before I have a conversation with whoever gets this fine amplifier and I won't be able to explain the hazards. It has as much as ~1600 VDC on the plate caps of the 805's during the 30 second startup phase. Once operating the voltage drops to a still a very lethal 1050 volts. There is a lot of energy stored in the HV power supply in this amp. I dread the day a spider gets in there and causes an explosion.
You just cannot afford to take any chances with power like this....period.
What kind of speaker is that you have in the picture. Looks like a very nice piano finish. I worked hard to get that on my 805 amp. 18 coats of hand rubbed lacquer between every coat!
ReinoutdV said:
I've got two darling house cats (children) so I have to be careful not to have anything potentially dangerous out in the open even if I'm right there. My amp in the system upstairs currently is a pair of HF-20 Eicos (P-P 6L6's) with some DIY mods. Those are perfectly safe with no top cages/covers IMO as there are no tube plate caps or exposed circuits at all.
Downstairs on my more serious system I have a MC3008AB Ming-Da which has been extensively modified by myself. It uses 300B's to cathode drive 805's in SET. Part of my mods was to make the tube cover well interlocked so the amp cannot function with the tube cage off. I know that I will die someday, probably before I have a conversation with whoever gets this fine amplifier and I won't be able to explain the hazards. It has as much as ~1600 VDC on the plate caps of the 805's during the 30 second startup phase. Once operating the voltage drops to a still a very lethal 1050 volts. There is a lot of energy stored in the HV power supply in this amp. I dread the day a spider gets in there and causes an explosion.
You just cannot afford to take any chances with power like this....period.What kind of speaker is that you have in the picture. Looks like a very nice piano finish. I worked hard to get that on my 805 amp. 18 coats of hand rubbed lacquer between every coat!
Attachments
HI All,
Thanks for fast answer, I didn`t consider that some big power tube are that easy to find.
Big thanks, ReinoutdV
We don`t see often a "mini review" for that kind of power tube! I appreciate a lot your comment.
No, I don`t wanna build a pushpull.
I will build an amplifier to drive my ESL. (acoustat)
I attempt to use an "direct drive" amp.
With some measuement, I find that I need 1400Volt peak per stator. So Big power tube are required.
My first idea was to use the 845. I planned to build a simple grouded cathode (one per stator) with resistive load (any choke will cause some "ringing" and I`m not a fan of current source)
But at 125Watts max and 1.25Kv, the 845 isn`t powerfull enough.
Even with 2 in parallel, It only give 1Kv Peak.
But I have a wonderfull 700ohm Zout (that will not cause early rolloff)
But 1Kv peak per stator isn`t loud enough to fully drive the panel for my taste... ok for most of the time but sometime, we want to listen very loud
My only choice is to build a bigger amp. With the 833, with 4.3Kv for b+, I can reach 1.6Kv peak with a single tube(should be better than 2 845 in parallel) but I have a high Zout (around 4Kohm)
4Kohm will result in a roll off of around -4Db at 20Khz. I can live with that. At least, I`ll add a ribon tweeter.
I would like to simulate some thing with the 572B but I`m didn`t find the RP of that tube...
I know that 4.3Kv is very dangerous voltage but I can live with that risk. Afterall, a pair of 845 with a 2300 volts supply is deadly too...
Thanks
Thanks for fast answer, I didn`t consider that some big power tube are that easy to find.
Big thanks, ReinoutdV
We don`t see often a "mini review" for that kind of power tube! I appreciate a lot your comment.
No, I don`t wanna build a pushpull.
I will build an amplifier to drive my ESL. (acoustat)
I attempt to use an "direct drive" amp.
With some measuement, I find that I need 1400Volt peak per stator. So Big power tube are required.
My first idea was to use the 845. I planned to build a simple grouded cathode (one per stator) with resistive load (any choke will cause some "ringing" and I`m not a fan of current source)
But at 125Watts max and 1.25Kv, the 845 isn`t powerfull enough.
Even with 2 in parallel, It only give 1Kv Peak.
But I have a wonderfull 700ohm Zout (that will not cause early rolloff)
But 1Kv peak per stator isn`t loud enough to fully drive the panel for my taste... ok for most of the time but sometime, we want to listen very loud
My only choice is to build a bigger amp. With the 833, with 4.3Kv for b+, I can reach 1.6Kv peak with a single tube(should be better than 2 845 in parallel) but I have a high Zout (around 4Kohm)
4Kohm will result in a roll off of around -4Db at 20Khz. I can live with that. At least, I`ll add a ribon tweeter.
I would like to simulate some thing with the 572B but I`m didn`t find the RP of that tube...
I know that 4.3Kv is very dangerous voltage but I can live with that risk. Afterall, a pair of 845 with a 2300 volts supply is deadly too...
Thanks
Hello again RCAvictim,
congratulations on your 805-amp. If it only sounds 1/10 of how it looks......you've kot a killer amp.
You're right about the safety features. You can not mess with these voltages. And currents: a 833 will gobble 20 amps during start up. Now that is something to take into consideration when doing your filament-wires......
I have to switch on 4 transformers in order to get "sound". The first is the powerline for filaments 6SN7/300B, the second is the powerline for B+ 6SN7/300B, third is the filament 833 and the fourth B+ 833. It is pretty straightforward but i did not want to use relais for they are prone to "stick". And that's not what you want with these amperes...
The speakers were former Monitor Audio Studio 50. 12 layers of piano laquer.....
Again congratulations with the 805 amp. Try that to buy in a store !
With regards,
Reinout
congratulations on your 805-amp. If it only sounds 1/10 of how it looks......you've kot a killer amp.
You're right about the safety features. You can not mess with these voltages. And currents: a 833 will gobble 20 amps during start up. Now that is something to take into consideration when doing your filament-wires......
I have to switch on 4 transformers in order to get "sound". The first is the powerline for filaments 6SN7/300B, the second is the powerline for B+ 6SN7/300B, third is the filament 833 and the fourth B+ 833. It is pretty straightforward but i did not want to use relais for they are prone to "stick". And that's not what you want with these amperes...
The speakers were former Monitor Audio Studio 50. 12 layers of piano laquer.....
Again congratulations with the 805 amp. Try that to buy in a store !
With regards,
Reinout
Attachments
4,3 kV B+
Hi Etalon90,
just checked my tube data and just a warning. A 4,3 kV B+ on a 833 is really pushing on the limit. You're already into forced air cooling but still then it's pushing.
If you're into that voltage......go for the 833C (or even D). Theycan take a real (heat-)hammering.
Reinout
Hi Etalon90,
just checked my tube data and just a warning. A 4,3 kV B+ on a 833 is really pushing on the limit. You're already into forced air cooling but still then it's pushing.
If you're into that voltage......go for the 833C (or even D). Theycan take a real (heat-)hammering.
Reinout
Attachments
NickC-reply
Hi NickC,
i missed you indeed ! Computer-glitch or maybe my quite aggresive spam-filter discarded your mail. In that case: sorry. But without the filter there is no live here on cable.
Good to hear you scored the sockets. So you don't need these anymore ?
As for my DAC: i started to collect all parts from all over the world. I even found some Silver Crowns.
And as for the 833-sockets. I'll find another "home" for them.
Are you still interested in the capacitors or did you manage to find these as weel. Or are you going for a totally different schematic ?
Now i'm corresponding with a bloke frome australie who is intending to make a 1600 W push-pull 833-amp. That will be a site to see. He will be rewarded class A status by the local power company !
Happy building,
Reinout
Hi NickC,
i missed you indeed ! Computer-glitch or maybe my quite aggresive spam-filter discarded your mail. In that case: sorry. But without the filter there is no live here on cable.
Good to hear you scored the sockets. So you don't need these anymore ?
As for my DAC: i started to collect all parts from all over the world. I even found some Silver Crowns.
And as for the 833-sockets. I'll find another "home" for them.
Are you still interested in the capacitors or did you manage to find these as weel. Or are you going for a totally different schematic ?
Now i'm corresponding with a bloke frome australie who is intending to make a 1600 W push-pull 833-amp. That will be a site to see. He will be rewarded class A status by the local power company !
Happy building,
Reinout
Attachments
ReinoutdV said:
Reinout,
Thanx for the compliments on my work. I went with two SS relays and low voltage DC control so I could get AC completely off the power supply toggle switch and Hi-B+ standby switch that shares the same copper shielded control enclosure as the low level audio volume control pots and source selector switch wiring. This amp, unlike as originally from the Ming-Da factory, along with many other improvements now has a choke input HV power supply and a separate 300 mA plate xfmer from Hammond. The HV regulation from idle to full power, 40 watts/channel, both channels driven is 0.1%. The amp has been in use now for about 6 months used several hours daily. I love it!
You are right about the high filament current issues, especially on turn-on surge.
Here is another view of my new 805 amp. I had bought this and done the modification as a prototype for an intended manufacturing run. I was planning to offer this item as you see it for sale. You're right, nothing quite like this in stores. Moth Audio has a 304TL monobloc that I'd compare this to I think.
Attachments
GU-48 picture
Hi again RCAVictim,
here's a picture of the GU-48 in full flight. Those 833's do double as a nice room heating system.......
As for your amp: priceless. One-of-a-kind. And yes.....Moth is into that retro-style. I think an interior designer could live with your amp. As for my amp: it has a "mechanical" style. No frills, just purpose. No design marks for me; which does NOT say it is not very well build. On the contrary !
About prices: did you check out the new Wavac SH-833 ? At $ 350.000 a SE 833-amp with external powersupply and external isolation transformer. In the Stereophile july issue there was a test with these heavyweights (288 Kg per channel). OK, mine are just 140 Kg per channel and lack the CNC-milled casing. But my powersupply is just as good. And the picture of the innards of the SH-833 were EXTREMELY dissapointing. Simply ****-resistors. Not even audiophile ones. For $ 350.000 is expect nothing but the best.
Oh.......my amps were nowere near the 350.000 mark. Not even close. Not cheap (surprise, surprise with 32 transformers) but a somewhat different price-region.
How many are they planning to sell ?
Keep up the audio-work. My current projects are a new pre-amp and a DAC. Both projects are underway.
Reinout
Hi again RCAVictim,
here's a picture of the GU-48 in full flight. Those 833's do double as a nice room heating system.......
As for your amp: priceless. One-of-a-kind. And yes.....Moth is into that retro-style. I think an interior designer could live with your amp. As for my amp: it has a "mechanical" style. No frills, just purpose. No design marks for me; which does NOT say it is not very well build. On the contrary !
About prices: did you check out the new Wavac SH-833 ? At $ 350.000 a SE 833-amp with external powersupply and external isolation transformer. In the Stereophile july issue there was a test with these heavyweights (288 Kg per channel). OK, mine are just 140 Kg per channel and lack the CNC-milled casing. But my powersupply is just as good. And the picture of the innards of the SH-833 were EXTREMELY dissapointing. Simply ****-resistors. Not even audiophile ones. For $ 350.000 is expect nothing but the best.
Oh.......my amps were nowere near the 350.000 mark. Not even close. Not cheap (surprise, surprise with 32 transformers) but a somewhat different price-region.
How many are they planning to sell ?
Keep up the audio-work. My current projects are a new pre-amp and a DAC. Both projects are underway.
Reinout
Attachments
Re: GU-48 picture
Great picture. I didn't know what a GU48 was. Pretty close copy to an 833A. If you are operating your plates that hot I'd suggest taking heed of what RCA suggests in theiir transmitting tube manual for the 833A. Airflow should be directed downwards into the space between the plate and grid terminals to keep the seals from failing from excess heat. The max continuous dissipation with convection cooling is CCS 300 watts, ICAS 350 watts. With forced cooling CCS 400 watts, ICAS 450 watts.
CCS= Continuous Commercial Service. ICAS = Intermittent Commercial and Amateur Service.
I could never have afforded to keep an amp like the 805 SET I now own thanx to DIY.
To justify the price that Wavac amp also comes with a $250,000.00 motor home and a $75,000.00 country acerage with docking port to park it, but they forget to mention this anywhere.
My 805 stereo amp only has 11 transformers and weighs about 130 lbs. I think you did a very nice job on your amp. The power supply chassis looks very pro.
ReinoutdV said:
Great picture. I didn't know what a GU48 was. Pretty close copy to an 833A. If you are operating your plates that hot I'd suggest taking heed of what RCA suggests in theiir transmitting tube manual for the 833A. Airflow should be directed downwards into the space between the plate and grid terminals to keep the seals from failing from excess heat. The max continuous dissipation with convection cooling is CCS 300 watts, ICAS 350 watts. With forced cooling CCS 400 watts, ICAS 450 watts.
CCS= Continuous Commercial Service. ICAS = Intermittent Commercial and Amateur Service.
I could never have afforded to keep an amp like the 805 SET I now own thanx to DIY.
To justify the price that Wavac amp also comes with a $250,000.00 motor home and a $75,000.00 country acerage with docking port to park it, but they forget to mention this anywhere.
My 805 stereo amp only has 11 transformers and weighs about 130 lbs. I think you did a very nice job on your amp. The power supply chassis looks very pro.
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