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Old 7th January 2011, 06:08 AM   #11
singa is offline singa  Singapore
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Quote:
Originally Posted by mpuman View Post
I too use google translate - works pretty good.

What about C Core & R Core transformers? Seem to be from a technical side a no-brainer as they are inherently gapped - but from the subjective side - how do they sound? Much lighter in weight and cost? Has anyone actually tried them & listened side by side? If they sound the same, sure would lighten the load both in weight and cost!
Hi mpuman,
From anectodal evidence and what I've read C and R core
transformers sound good or at least you will get the attention of
audiophiles. Audionote UK uses C cores in their top notch products like
interstage and power transformers.So if you can use them why not?
Lundal makes it's transformers using C/R cores.Maybe they can custom wind for you?
Regards.
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Old 7th January 2011, 12:48 PM   #12
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mpuman

A couple of thoughts about the 805 kit.

I built a pair of Moondogs many years ago and was very happy with the outcome.

Recently I decided to replace them with a 45 based amp, and finding nothing I liked in kit form I just built my own.

Now that I have done it I believe that I did the correct thing as I see that I had the opportunity to make the choices of what to use for the circuit, chassis, resistors, capacitors and transformers.

That is not to say that your choices will not be good but by building my own I made my own cost / sonic choices.

The additional work of deciding on parts finding them was a fun filled treasure hunt, and the mechanical work was not that difficult.

I have often since thought about another project and the 805 has received a lot of consideration but with Lowrthers I feel that they would be a bit much for my system.
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Old 7th January 2011, 07:28 PM   #13
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Originally Posted by golddustpeak View Post
mpuman
The additional work of deciding on parts finding them was a fun filled treasure hunt, and the mechanical work was not that difficult.

I have often since thought about another project and the 805 has received a lot of consideration but with Lowrthers I feel that they would be a bit much for my system.
Yeah! just kind of a little overkill! Might just fire the drivers into the next room!
Back in the 80's and early 90's I had audiopile low efficiency speakers and built all kinds of 800 series transmitter tube amps, including 805, 813, 808, ...and even 833's. Many were A2 of course. Fun stuff.
They were space heaters that made music!
I still have some knarly deadly power supplies.

But then I went back to high efficiency speakers and am now running SE 45 amps and the like. 3 watts will fill my 900sq ft room to nose bleed levels.
I still occasionally play with the big boys, just for the heck of it though.

BTW: Mpuman, if you are doing the amp for yourself then by all means use 866 rectifiers. They look cool and by absolutely no means do they adversely affect dynamics/transients, despite gross generalizations to the contrary. Better yet, use 866's for the output stage and 816's for the input/driver. However, for a commercial kit, silicon diodes might be a better choice.
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Old 7th January 2011, 08:12 PM   #14
mpuman is offline mpuman  United States
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I am investigating C & R cores. Seems to me a lot of voodo in iron! How much is for real and how much is illusion is difficult to judge. So much of it is subjective / smoke & mirrors. The illusion that more $$ is better. I really don't think that is always the case. As I have proved time & time again with other products, the key is in design & purchasing power.

My domestic magnetics guy is not really into audio - his contention is its 'mostly all **' ... then again he does not see why anyone would mess with tubes and 'hears' nothing wrong with mp3's - so he is not much help!

I got some quotes for some 'well named' transformer mfgs for the project. For EI nickel core version vs 'normal' HiB it's like $1400 vs $900 for each side! Is nickel worth $500 more (just for interstage / output)? Anyone with real A/B experience - perhaps in blind tests?

The idea behind my attempt is to make available a very reasonable priced package that is superior to the China 805 stuff and less than say Wavac. Obviously, the China 805 stuff is not using these style xfmrs!

Since it would be a kit, each builder could modify stuff like caps / resistors / tubes, but ideally the kit would be the best it could be for the price - including one's time.

The hope is to supply a complete kit in the <$1K a side range that is comparable to the $5K a side factory built units. From what I see now, we can do it for <$2K with the 'normal' HiB xfmrs. I want to get to the <$1K - then I think we will have something.

Next item on my list is the chassis. I have plenty of CNC machine shops that can do the whole deal as machined AL. I have CNC sheet metal shops that can do it in stainless steel. And lastly we could so an 'exotic wood' & metal combo. All have various advantages & disadvantages & costs. Any ideas?

The quest continues. I have always been into electronics. Having your hobby also as your vocation is very dangerous! Please keep the comments coming.
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Old 7th January 2011, 11:32 PM   #15
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Quote:
Originally Posted by mpuman View Post
I am investigating C & R cores. Seems to me a lot of voodo in iron! How much is for real and how much is illusion is difficult to judge. So much of it is subjective / smoke & mirrors. The illusion that more $$ is better. I really don't think that is always the case. As I have proved time & time again with other products, the key is in design & purchasing power.
Well, there is a lot of art in transformer design. You are optimizing a large number of parameters simultaneously. What you pay for is experience.
Not that there isn't also a good deal of hype, but that is the norm for audio, sigh.

Quote:
I got some quotes for some 'well named' transformer mfgs for the project. For EI nickel core version vs 'normal' HiB it's like $1400 vs $900 for each side! Is nickel worth $500 more (just for interstage / output)? Anyone with real A/B experience - perhaps in blind tests?
I have done one comparison. It was an output transformer, from a well known audio supplier. I compared a pure M6 (as I recall) to one with nickel stripes. It was not completely apples to apples because the striped version had a lower Idc spec and was parafeed configured. However, the difference was noticeable. I used the striped version.

I have compared all nickel input transformers to conventional ones that were very similar but not exactly the same. I drew the same conclusion.

Not exactly proper scientific comparison, but an anecdotal data point. It was enough to convince me to use nickel, when I could.

Quote:
The hope is to supply a complete kit in the <$1K a side range that is comparable to the $5K a side factory built units. From what I see now, we can do it for <$2K with the 'normal' HiB xfmrs. I want to get to the <$1K - then I think we will have something.
That sounds like a reasonable price point. I doubt you would have any room left for your own profit though. That sounds right about rock bottom for the BOM.

Quote:
Next item on my list is the chassis. I have plenty of CNC machine shops that can do the whole deal as machined AL. I have CNC sheet metal shops that can do it in stainless steel. And lastly we could so an 'exotic wood' & metal combo. All have various advantages & disadvantages & costs. Any ideas?
Gee, any of the above sounds nice, but of course we would have to see the concept to make a decision on materials.

Quote:
The quest continues. I have always been into electronics. Having your hobby also as your vocation is very dangerous! Please keep the comments coming.
Yeah, ditto here. But my day job is in RF IC design so the two are so far apart, it almost doesn't have overlap.
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Old 8th January 2011, 08:38 PM   #16
mpuman is offline mpuman  United States
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hey funkytek, sounds like we have a lot in common. We have done some RF board level stuff here. RF ... talk about black magic, only audio is close in that department - you are closer than you think. But with digital RF, a lot of the art seems to have gone away (but I'm sure not on your side).

Not really in to this for much profit. Yes, we have to make something, but not that much. With our buying power, we still would have a nice but not excessive margin.

OK, more on xfmrs. Why not do them like they used to be done? That is paper bobbins instead of nylon with paper layered between layers? That's what they did back in the day. Perhaps the low tech way is still the way to go - but with better steel. My old time xfmr mfg sez it's the way to do them. I am willing to give them a try - after all they have been making audio xfmrs for 60+ years. Perhaps I will also have them do a couple with nickel just for the fun of it.

I also have a guy working on a more exotic design with some very special core materials that he contends are very promising. Will see.

Lastly, I was planning on CC for the heater supply of the 805. What about CLC? Looks like 22,000uF X 25mH X 22,000uF would give plenty of filtering while providing kind of a 'passive' CC. Just seems to me that when one puts a gain stage in the circuit (typical of CC regulator design ala LM338 etc), stuff is going to happen to effect the audio. Or am I going too far?

Separate filament and B+ xfmrs will allow easy sequenced power up and standby modes. Even more iron! Looks like 5 or 6 pieces of iron, 3 valves, some resistors and caps. Gee, it's like something out of the 1920's (less the regulated bias supply for the 805).

Well, with some good ideas floating around, looks like the next step is to get some iron wound up and get a couple test beds set up so I and others can take a listen. Have a couple guys in the Pittsburgh area that are 'audiophiles' to help with the subjective side. Others are welcome when we get that far. If you are close by, let me know.

Actually once I get some protos wound, if there are folks out there that actually have Shishido 805 designs, I would be very happy to ship them some xfmrs to audition vs their ex-Tango, etal iron ...

I guess the reason I even did the posting is to give me the motivation to turn the crank. So far it has helped.

OK, I've got a plan. Time to put together some monster passives and stuff to have parts to work with. Other than SMPS and motor controls, have not done much power and HV work for a while - need parts. If nothing else I'll waste some $$, but get back to some hobby fun!
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Old 9th January 2011, 12:10 AM   #17
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Originally Posted by mpuman View Post

Lastly, I was planning on CC for the heater supply of the 805. What about CLC? Looks like 22,000uF X 25mH X 22,000uF would give plenty of filtering while providing kind of a 'passive' CC. Just seems to me that when one puts a gain stage in the circuit (typical of CC regulator design ala LM338 etc), stuff is going to happen to effect the audio. Or am I going too far?
Switching power supplies are your friend. I modified some 5v switchers to 6.3 to power an 811A. All decent switchers have isolated secondaries so you don't have to worry about grounding issues. Run two 5v supplies in series. One thing to keep in mind is that any silicon you use will need to be properly heatsinked.

My opinion is that filament chokes are impractical at high currents. A two dollar linear regulator makes much more sense.


Quote:
Originally Posted by mpuman View Post
Separate filament and B+ xfmrs will allow easy sequenced power up and standby modes. Even more iron! Looks like 5 or 6 pieces of iron, 3 valves, some resistors and caps. Gee, it's like something out of the 1920's (less the regulated bias supply for the 805).

Well, with some good ideas floating around, looks like the next step is to get some iron wound up and get a couple test beds set up so I and others can take a listen. Have a couple guys in the Pittsburgh area that are 'audiophiles' to help with the subjective side. Others are welcome when we get that far. If you are close by, let me know.

Actually once I get some protos wound, if there are folks out there that actually have Shishido 805 designs, I would be very happy to ship them some xfmrs to audition vs their ex-Tango, etal iron ...

I guess the reason I even did the posting is to give me the motivation to turn the crank. So far it has helped.

OK, I've got a plan. Time to put together some monster passives and stuff to have parts to work with. Other than SMPS and motor controls, have not done much power and HV work for a while - need parts. If nothing else I'll waste some $$, but get back to some hobby fun!

Hey I'm in the Pittsburgh area as well
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Old 9th January 2011, 02:28 AM   #18
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Originally Posted by mpuman View Post
The hope is to supply a complete kit in the <$1K a side range that is comparable to the $5K a side factory built units. From what I see now, we can do it for <$2K with the 'normal' HiB xfmrs. I want to get to the <$1K - then I think we will have something.
I am working on a Simple 845 SE stereo unit (but could be configured as mono-blocks) @ 20 Watts RMS per channel. I should be able to post the schematics and BOM by the end of January. No kit, but just a basic design to try and get more DIYer's into transmitting tube amps.

I think I can get the design BOM to around $750USD if you are frugal in buying the parts. This will by no means be designed with the "best" parts, but just a starting point for people to try. They can experiment and try different heater circuits, front-end circuits later, if needed.

The designed will be built and verified, not just an idea.
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Old 10th January 2011, 07:59 PM   #19
mpuman is offline mpuman  United States
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Hi THD+N - sounds like your 845 could be a good entry point. I want to do the 805 for more power since a lot of PP guys need more power for their inefficient spkrs sys. This will give them an easy way to give a try to SE.

The kit idea is geared towards diy'er naturally - I think that we will offer semi-kits as
well (e.g. less glass, less chassis, etc). That way the true DIY guy can get the main parts and roll some of his own. I'm guessing that a lot of guys will want the full kit - assuming that the sound review is VG - which I expect it will - otherwise we don't have a product.

Spoke with yet another domestic iron guy that has been around for 60+ years. I think we may have a good fit on the iron for performance vs cost objectives. I think we are real close to that <$1K a side (depending upon options). I'll know more as the week progresses and time allows.

astouffer, I have a lot of experience with designing switchers. Although their noise can be outside of the audio range, way too much of a chance for a production kit. I have determined that CCS for the 805 will be what we will do. If you get a chance, drop me a PM and let talk - I'm sure that we can be an asset to each other.

In the next week or two, I'll post our proposed sch for everyone's comments - good & bad. Then the wait for the various samples of iron ...
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Old 10th January 2011, 08:24 PM   #20
316a is offline 316a  England
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Originally Posted by mpuman View Post
Hi THD+N - sounds like your 845 could be a good entry point. I want to do the 805 for more power since a lot of PP guys need more power for their inefficient spkrs sys. This will give them an easy way to give a try to SE.
Why not just 'breathe' on a commercial Chinese 805 amp ? That would solve your prototype issue at a stroke . At the end of the day 40 watts from an 805 is only 3dB more than 20 watts from an 845 . 20 watts will hit 100dB peaks easily with 88dB speakers . Unless the user has a huge rooom , far more than they'll ever need .

Quote:
astouffer, I have a lot of experience with designing switchers. Although their noise can be outside of the audio range, way too much of a chance for a production kit. I have determined that CCS for the 805 will be what we will do. If you get a chance, drop me a PM and let talk - I'm sure that we can be an asset to each other.
With a cap input supply it can be done but the CCS will need a large heatsink and even a ring of two will dissipate several watts .

I personally think that an 805 kit is not worth it , especially with the complexity , costly output transformers and high voltages . It will no doubt be a real money pit in terms of development and think of the support you'll have to offer when people's builds go wrong

Good luck !

316A
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