POWER SUPPLY
A lot depends on your power supply. I never impose the ps on diyers, but my power supply is actually with tube rectifiers (5R4 for stiffer more composed sound, 5U4 for beefier sound...) and the following LCLC: 10H - 500uF - 10H - 500uF. The 500uF are large computer grade units and bypassed with 1uF poly caps. The 10uF is usually a motor starter cap in a can, while the Rk of the output tube is bypassed with tantalum bypassed with poly caps...
Just take a look at my RPA preamp (on my site)to get an idea of my choice of elements and power supply types 🙂
A lot depends on your power supply. I never impose the ps on diyers, but my power supply is actually with tube rectifiers (5R4 for stiffer more composed sound, 5U4 for beefier sound...) and the following LCLC: 10H - 500uF - 10H - 500uF. The 500uF are large computer grade units and bypassed with 1uF poly caps. The 10uF is usually a motor starter cap in a can, while the Rk of the output tube is bypassed with tantalum bypassed with poly caps...
Just take a look at my RPA preamp (on my site)to get an idea of my choice of elements and power supply types 🙂
Since I've a pair of RCA 807 JAN, might as well go for it!
Being a newbie, unfamiliar with it's pinout. Where on the schematic should I connect the cap to?
Read somewhere that running this 807 at 500v is pretty low!??
As usual, I'm thankful for any contribution forecoming.
Cheers,
Zekk
Being a newbie, unfamiliar with it's pinout. Where on the schematic should I connect the cap to?
Read somewhere that running this 807 at 500v is pretty low!??
As usual, I'm thankful for any contribution forecoming.
Cheers,
Zekk
Zekk-
re:807 pinout
You should bookmark your favourite tube data pages- you will be needing them.
http://tdsl.duncanamps.com/tubesearch.php
is one good one.
Cheers
John
re:807 pinout
You should bookmark your favourite tube data pages- you will be needing them.
http://tdsl.duncanamps.com/tubesearch.php
is one good one.
Cheers
John
If I recall correctly, it's "anode cap" so you should connect it to the anode 🙂
If you are building the RH807 with 807s, than please stick to the values given in the schematics... if you want it to last you any relevant time.
There are other tubes in the same sub family that can be used with higher B+ and eventually have higher anode dissipation: you can use those in the same schematics, eventually adjusting the Rk of the output tube to fit the anode dissipation specs... and in the end get more output power.
PT Transplant.
Can I uses a vintage power transformer removed from a Fisher X-100 that drives 11 tubes for RH84SE?
Readings on secondary are 350-0-350.
Wish to up-grade with beefer componants for my RH84SE re-built.
Thanks,
Zekk
Can I uses a vintage power transformer removed from a Fisher X-100 that drives 11 tubes for RH84SE?
Readings on secondary are 350-0-350.
Wish to up-grade with beefer componants for my RH84SE re-built.
Thanks,
Zekk
Hi Alex, 807 is such a beauty but why it doesn't fetch much on ebay? I'm planning to build one of those as my first tube amp but I only have a a pair of cheap 5K edcor to try it out. What is the penalty not to use 6K as in your schematic? Thanks for your refreshing design idea.
It is not a particular problem whether you will use a 5k or 6k primary... bear in mind that the primary Ra is a reflection of the secondary load: i.e. 6k primary to 8 ohm, but you connect 6 ohm loudspeakers... and you end with a different than 6k primary...
Furthermore, the specifics of the circuit make the amplifier quite forgiving when it comes to Ra.
If the 807 does not cost that much on ebay or elsewhere it can only be a good thing! But, not all 807s are created equal: Brimars are probably among the best.
Furthermore, the specifics of the circuit make the amplifier quite forgiving when it comes to Ra.
If the 807 does not cost that much on ebay or elsewhere it can only be a good thing! But, not all 807s are created equal: Brimars are probably among the best.
Ipanema said:
Few valves with plate caps go for big money. TT21 being a notable exception, due to its relationship to the KT88.
cheers,
Douglas
Hi Alex, I just bought a pair of Pinnacle 807. Are they any good?
Can I use 12AU7 instead of ECC81? Just need to find some reason to use them instead of collecting dust.
Can I use 12AU7 instead of ECC81? Just need to find some reason to use them instead of collecting dust.
Hey guys,
I've been looking at building this amp as a starter for an all-tube project, and I'm pretty excited!
Would I have to tweak the circuit at all to accommodate either a 12AU7 or a 6EJ7 tube? I've read on here that the 6EJ7 runs super-linearly when it's triode strapped, hmm...
So I guess I'm looking for an explanation about which values need to be tweaked and how you know to do that so that I can understand what's going on-- I'm an SS guy, you see, so electronics don't scare me!
Thanks,
Philip.
I've been looking at building this amp as a starter for an all-tube project, and I'm pretty excited!
Would I have to tweak the circuit at all to accommodate either a 12AU7 or a 6EJ7 tube? I've read on here that the 6EJ7 runs super-linearly when it's triode strapped, hmm...
So I guess I'm looking for an explanation about which values need to be tweaked and how you know to do that so that I can understand what's going on-- I'm an SS guy, you see, so electronics don't scare me!
Thanks,
Philip.
thefragger said:
Philip-
I'd recommend building the RH84 'straight' from the schematic if it is your first tube amp.
You can always do the experiments on a later project.
And, although you will get lots (well, mostly..) of good advice here at diyaudio, Alex Kitic is not very patient about questions about changes to his designs, so be forewarned.
Cheers
John
VictoriaGuy said:
Thanks John, though this is my first tube amp, I've made a tube/MOSFET amp already, but it's getting a handle on why the part values the way they are is what I'm not understanding.
I'll figure it out; thanks again 🙂
Philip.
thefragger said:
The whole point of an RH amp is to make a pentode amp perform in the same sonic range as if triode strapped but with at least 2x the power.
The 12AU7 probably doesn't have sufficient gain or high enuff output impedance to work.
The tubes you suggest may make a fine SET but it won't be any relation to an RH84.
dave
planet10 said:
Thanks Dave, I understand. Luckily I found a 12AT7 in the bottom of my stash! 😀
Alright, so I've got all the parts and I'm ready to make this, I just have one last question; how much current should the power supply be able to put out?
Philip.
RH84 chassis and construction choices
I'm soon going to embark on my first DIY valve amp - the RH84.
The iron donor is a Sony TC500A RtR deck.
I have read through a number of threads and seen various different approaches to the physical layout of the components. My personal aesthetic preference is for a timber-sided plinth, with the valves visible on top and the iron and other components hidden below.
The alternare schemes are:
1. Iron on top also; and
2. everything concealed in the box.
What are the relative merits of each layout? Is one likely to be sonically superior?
Thanks
Doug
I'm soon going to embark on my first DIY valve amp - the RH84.
The iron donor is a Sony TC500A RtR deck.
I have read through a number of threads and seen various different approaches to the physical layout of the components. My personal aesthetic preference is for a timber-sided plinth, with the valves visible on top and the iron and other components hidden below.
The alternare schemes are:
1. Iron on top also; and
2. everything concealed in the box.
What are the relative merits of each layout? Is one likely to be sonically superior?
Thanks
Doug
Doug-
Putting the iron on top of the chassis is structurally better- it's easier to support the transformers/chokes from below than to 'hang' them from fasteners. You can also have a much 'lower profile' chassis with the iron on top. So probably easier to keep the iron on top.
That said, there are certainly lots of examples of commercial products with everything inside the case, so that would be another possibility. However, it's a lot harder to get rid of heat with a fully enclosed case- I once heard an AudioNote tube amp (6L6) that was hot enough that even the volume knob (gold-plated metal) was warm to the touch.
Don't forget that you need to have either the bottom plate or the case top/surround removable and it is best to have them unencumbered with components. So, if the bottom plate is the removable 'access door', you really don't want components attached to it. So if your iron is 'inside' you will probably need to build a sub chassis of some sort.
I think the Eric Kingsbury (Pointz) style chassis is a great-looking and simple solution (if you have some woodworking skills). See
Audiotropic.net for examples.
I used this style chassis for my RH and it worked well. Leave yourself plenty of room in case you decide to experiment with larger coupling caps, etc.
Cheers
John
Putting the iron on top of the chassis is structurally better- it's easier to support the transformers/chokes from below than to 'hang' them from fasteners. You can also have a much 'lower profile' chassis with the iron on top. So probably easier to keep the iron on top.
That said, there are certainly lots of examples of commercial products with everything inside the case, so that would be another possibility. However, it's a lot harder to get rid of heat with a fully enclosed case- I once heard an AudioNote tube amp (6L6) that was hot enough that even the volume knob (gold-plated metal) was warm to the touch.
Don't forget that you need to have either the bottom plate or the case top/surround removable and it is best to have them unencumbered with components. So, if the bottom plate is the removable 'access door', you really don't want components attached to it. So if your iron is 'inside' you will probably need to build a sub chassis of some sort.
I think the Eric Kingsbury (Pointz) style chassis is a great-looking and simple solution (if you have some woodworking skills). See
Audiotropic.net for examples.
I used this style chassis for my RH and it worked well. Leave yourself plenty of room in case you decide to experiment with larger coupling caps, etc.
Cheers
John
Attachments
VictoriaGuy said:
Thanks John,
I think you've covered the pros & cons nicely.
I have my doubts that I can arrive at something beautiful first up, so I think I should try to achieve the desired layout in a mock-up chassis. To give me a staring point, can you provide the dimensions of your pictured amp?
After I get the amp built and working, I'll build the final housing/plinth.
Thanks
Doug
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