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05-16-2018

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devo_yan
Posts 7
Joined on 05-16-2018

Post #:	1
Post ID:	24860
Reply to:	24860

250 watts Parallel S.E. advises

Hello every body, I live in France and I'm new on this forum.

I'm thinking to build (some months) a mono big Single Ended amplifier (200-300 watts) made with triodes (IDHT or DHT doesn't matter for me) for outdoor professional audio.

Have you got an online store to advise to me for custom output transformers and power transformers ? (I have to admit that I'm more looking for cheap price than high grade =s)

On internet I found "toroidy" that seem to be good.

After many thinking, for final stage I think to use
- 10 parallele 845 (psvane) running at something like 1000V (24 watts per tube in A1). (any other advise ?)
- 2 or 3 845 for driver (running at 1000V too (choke and capacitor coupled))
- 1* 300B (choke and capacitor coupled )for to drive the driver stage (with it's own power supply (400V))
- 1* 6J5 (half 6SN7) (or 6sn7GT with both triodes in parralele) carbon resistors/capacitor coupled to drive the 300B (they will share the same power supply than the 300B)

both power supply with
- center tappered tranformer and full wave tube rectified (5Z3 for 400V, 836 for >1000V)
- LCLC filtered (no solid state regulated)

Every tubes will be self bias and without negative feedback.

How much can I expect it weight ? 100Kg ? More ?
Any advise welcome = )))

*

I often read that S.E. are not good for to properly drive big basses speakers, do you know why ?

I mean why for example a 300B S.E. could produce wonderfull basses when driving a 5" basic sealed speaker and can't properly drive bigger speaker ? Is it because of the poor damping factor ? (I mean the speakers drive more the amp than the amp drive the speakers ^^)

If yes how to increase it ? Someone told me that I need very high current (like plenty 6c33 in parralele or solid state). But why ? with the output transformer the speaker should already see low impedance, right ?

05-16-2018

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xandcg

Rio de Janeiro, BR.
Posts 218
Joined on 09-07-2014

Post #:	2
Post ID:	24861
Reply to:	24860

Power supply.

I am far from the best person to comment on it but your biggest problem would be the (huge/gigantic) power supply. And I confess I do not know if it is possible to parallel more than two output valves on SET fashion, I never saw it but the ultralinear amplifiers.

For behemoths SETs you are looking for, you will need to choose between some big transmitters valves like 833A, Eimacs, QB5/1750, or ever GM100 (among others).

There is this thread about a related subject: http://goodsoundclub.com/Forums/ShowPost.aspx?PostID=2136

Think for yourself, do not be sheep.

05-16-2018

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devo_yan
Posts 7
Joined on 05-16-2018

Post #:	3
Post ID:	24862
Reply to:	24861

Thank you

Hello, thank you for your answer,
I already read this very interesting link (this how I knew about this forum (like "yes ! there is weird people too"))
I never saw too much parellele things too (excepte for solid states); I hope nothing is wrong doing it

I hope some other peoples will answer to this thread
The question is:
"if you really really would love to do a big S.E. amp with triodes for to power four 18 inch Band Pass Horn bass speaker, that can drive them very well, what will you do ?"
(I want S.E. because from my few experiences I have an ever better feeling with S.E. (I have nothing against P.P. don't worry), and the same for triode instead of triode connection penthode (even if I didn't tested so much pentodes in triode connection))

I would like to do it cheap (it will be a kind of usable test), let say 3000e (I have nothing against less, (no I will not use Tango Hirata transformers for this project)) and at least 100 watts in A1 (because my bed is very long and I want to be sure to hear the bass when I'm in my 13m2 bedroom with 106dB/1watt/1meter speakers (I'm joking))

I don't speak english very well so don't hesitate if you don't understand something..

05-16-2018

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xandcg

Rio de Janeiro, BR.
Posts 218
Joined on 09-07-2014

Post #:	4
Post ID:	24863
Reply to:	24862

Not cheap but.

Beyond those well know "audiphiles" transformers there is the Ogonowski also. This is the transformer Lapizator use.

That should not be cheap, and I think you may have problems to find a cheap (probably) custom transformer for you project

You may also look for some info at the Thomas Mayer blog.

Think for yourself, do not be sheep.

05-16-2018

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devo_yan
Posts 7
Joined on 05-16-2018

Post #:	5
Post ID:	24864
Reply to:	24863

My answer

Nice thank you for the link, see the "lo SE100-1", 169.0 USD for 7Kg, it's cheap and they look good.

So I was Happy with my choice of parallel 845 (I was hesitating with GM-70 but after a difficult decision I decided that the GM-70 filament consume twice the power of the 845 (and all of a sudden I felt concerned by power consumption (as much as someone wanted tube class A can be)).
But now that I read "How to get a LOT of SET power" again, I'm thinking about
GM-100
but because I will need to run her with 2500V plate, the Output transformer and the power transformer will need to be far bigger than parralele 845-GM70 right ?

or 833
but the need to run her in A2 scary me

what about 50 parallel 6as7 ? (maybe after soldering 10 of them I will hate me)

If someone could explain me what is the secret for to have good basses with S.E. amp (without negative feedback) ? Does it have something to do with the low impedance of the final stage tube(s) ? So would parallele 845 drive better big bass speakers than GM-100 for example ? or does it have absolutly nothing to deal with ?

05-16-2018

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xandcg

Rio de Janeiro, BR.
Posts 218
Joined on 09-07-2014

Post #:	6
Post ID:	24865
Reply to:	24864

Output transformer.

Hi.
Just remembering I am not technically capable to do any actual statement.

About the GM-100 I guess so. NatAudio has an amplifier using GM100 but with solid state power supply. Magma.

As you certainly know the actual result will be a consequence of all decisions you did; however you are looking for an amplifier to work on narrow bandwidth, and so you would be better to use optimized output transformers, with narrow bandwidth. In this case, just for bass.

Search in the forums about the Romy Malquiades amplifer and the DSET concept, and you will probably answer your-self later about that (at least partially).

For those high powered transmitting triodes you may want to take a look on rectifiers like PY500 too, and they are cheap. :-)

Think for yourself, do not be sheep.

05-16-2018

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devo_yan
Posts 7
Joined on 05-16-2018

Post #:	7
Post ID:	24866
Reply to:	24865

Reading about Malquiades amplifer and the DSET concept: check !

I already have some PY500 (it's a sign =))) ) and I have 836 too.

I read about Malquiade amplifier threads.

So it seem peoples on this forum like horn speakers (I love them too) and are looking for fast transient response, it's exactly what I like.
But I'm not sure to understood all particularities of the Malquiade amplifier
Maybe it have a fast transient response sound because of:
- only two stages amplifier
- the driver is resistor/capacitor coupled, I guess it's faster than poor choke or interstage transformer.
- very low impedance final stage power supply (I like to do it too =))) )
- no automatic bias (I do it for convenient raisons =s), I guess the time the cathode capacitor charge and discharge we lost speed

And if I understood well, for the 6 channel system, each channel have a optimised bandwith output transformer right ? This is what mean Dedicated SET ?

But I still don't understand the secret for a S.E. amp drive well big bass speakers. To simply use a good output transformer, this is the key ? And it's more easy to build good O.T. for low impedance tube this is why I often read that low impedance final stage tube is better for bass ?
I mean with a very good output transformer, even a 45 DHT can properly drive 4* 18" bass speakers ?

I said that I want to build a S.E. amp for to drive 4 18" BPH speakers but in fact I would like to drive a full range system with passive filters:
- 4* 18" band pass horn
- 1* 10" horn speaker
- 1* 1.5" horn speaker

Is it possible to have good sound with passive filter or will I really need to do 1 amplifier per channel with active crossover (crossover before the amplifiers) ?

(I ask to much questions in the same time)

05-18-2018

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	8
Post ID:	24871
Reply to:	24866

So what?

devo_yan wrote:
So it seem peoples on this forum like horn speakers (I love them too) and are looking for fast transient response, it's exactly what I like.

Horns are not serving “fastest transient response” the direct radiators do. I do not feel that going after ONLY fastest transient response is a right direction to go. Idel your amplification more and you your have more transients. So what?

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

05-18-2018

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devo_yan
Posts 7
Joined on 05-16-2018

Post #:	9
Post ID:	24872
Reply to:	24871

Sorry

Ok, I said a mistake, I like direct radiator (sealed speakers) too, but I often noticed more dynamic with horn speakers (I like every speakers (if properly tunned) except speakers that radiate with both sight of the drivers (bass-reflex, tapped horn, horn-reflex, rear loaded horn...)) but it's not the subject.

About my project, I will probably chose GM-100 for final stage (I sent an email to http://www.ogonowski.eu/ in purpose to know if they would be able to build GM-100 power and output tranformer).
So someone know if we can get strong bass with a 10Y (VT-25) S.E. driving 4* 18 inch bass speaker for example, if yes what does it need, only good output transformer ? Or does too small S.E. amplifier not able to drive too big bass speaker ?

How should I run the GM-100, 3000 volt on the plate and -70 volt on the grid (that should give 300ma (900W plate dissipation)) ?
So 10 000 ohms output transformer (turn ration 35:1 for 8ohms)
so if the grid swing 140 Peak to peak it mean 48 volts RMS/35 (turn ratio)*18 (GM-100 approximative gain) ~= 24 volt in the 8 ohms speakers = 72 watts in A1. So I will need to run the GM-100 in A2 or to run her with higher plate, right ?
What is the recommanded plate voltage and negative grid voltage for to run a GM-100 at full power in A1 ?

I never played with 3000 volt power supply, and I all time used amplificateur case made by 18mm wood, is there any risk to don't use metal grounded case with such voltage ?

Thank you.

05-27-2018

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	10
Post ID:	24890
Reply to:	24860

GU-80

You may take a look at GU-80. It's a DHP but some report excellent sound. I had some ideas regarding it:

http://goodsoundclub.com/Forums/ShowPost.aspx?PageIndex=3&postID=16064#16064
Cheers, Jarek

Cheers,
Jarek
STACORE

05-29-2018

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devo_yan
Posts 7
Joined on 05-16-2018

Post #:	11
Post ID:	24897
Reply to:	24890

GM-100

I read about the GU-81 penthode. It's probably a good possible solution, thank you.
I haven't so much experience with penthode, from my very few experiences, I felt better with triodes (DHT or IDHT), so I prefer don't take any risk.

I feel more and more attracted by the GM-100 (after reading again that parralele many triodes seem to be a bad idea)

So I think to use it like this:
3500 Volts on the plate 250mA (-120 volt automatic bias (carbone wounded resistors and paper in oil cathode capacitor (or blackgate if possible))
It should allow 160 watts output power in A1 (right ?)

So I should need:
- 2*2600Volt 200ma (so 400ma) power transformer (1040 watts) (2 times in purpose to do full wave rectifier with only two tube rectifiers (836))
- 14 000ohms: 8ohms; 4ohms; 2ohms output transformer. (how much power output transformer should I chose for 160watt A1 ( a little bit more in A2 and high crests factor) ?)

05-30-2018

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	12
Post ID:	24900
Reply to:	24897

Driving the direct heated and why do you need so much power?

Devo, the GM-100 for sure is a good triode to get 160 watts output power in A1. Still, it would be a good chose, from my point of view, ONLY from a prospect of embracing as good DIY audio project. There is nothing wrong then to do the good DIY audio projects, it for sure better then to drink vodka or sniff cocaine. Still, I would not recommend to confuse the enjoyment of having a good DIY audio project with opportunity to get a better sound.

What I am trying say that the GM-100 is a complex project and if you have an objective to drive with this thing your entails playback then I think it is set to be failure before it started, or what I call system architectural failure. Let me to explain. You are planning to drive with GM-100 the “full range system with passive filters”. Your HF or MF or Upper bass range need no 160 watts, it hardly need 10 even if you have a large room. Your array of 4 by 18” in BPH enclosure would not need more then 20W and it is closed-bottom it means it will not consume endless power at ULF and your BPH will act as very aggressive high pass filter. If you are one of those who will get 15Hz out of BPH type of loading by driving insane power into the drivers and exert them as direct radiators then you pretty much stop read this site. :-)

Now, let see what will you pay for your, in my view unnecessary 160 watts. Having the 3500 Volts on the plate and 250mA you would need an output transformation with at least rated for 5000-6000 volts. The insolation for the turn of this power will be very dramatic, so the impact to the capacitance. To get HF you will go to crazy sectioning but to do it at 6000V is a huge problem, you will still have a lot of HF destroying capacitance in that transformer. So, we do know that in your full range applier the HF will be compromised. The question why to build it…?

I understand if you have open bottom ULF channel that you would like to drive into oblivion with a lot of power. Then you get LF-only, no-sections, high capacitance transformer with a lot of core mass and huge amount of inductance. Then you drive your direct heated GM-100 with some kind of super powerful current source in order to let the GM-100 to be pushed on the right side of graph and let it to run with grid currents if it incidentally needs to. You for sure do not want to have the amp like NAT Audio where GM-100 is driver by super flimsy 1n1p. Not that it is wrong and with 160 watts you will be siting deep into A1 but if you have a playback the need to consume 160 watts to run then why do not make a provision that it will not hard-clip at 165 watts? The point if that the direct heated can run semi-fine in A2 and they do soft clipping, it is shame not use it with DHT….

Anyhow, all about is so much not your case with 4 BPH boxes…

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

05-30-2018

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devo_yan
Posts 7
Joined on 05-16-2018

Post #:	13
Post ID:	24901
Reply to:	24900

Active filtering

Thank you for your answer.

If I understand well, In purpose to do something realistic and good sounding. I should use at least 2 amplifiers (one for high frequencies and the GM-100 amp for low frequencies) with a tubes active filter at the inputs of each amps.

So I will have to ask for a custom O.T. that can do 20Hz (or 30Hz) up to 250Hz (or more) for the GM-100
And a O.T. that can do 200Hz-30 000Hz (or more) for a 300B or GM-70 amp
This is what DSET mean, right ?

Yes I read a lot that a good driver is very important, and running in A2 without any clipping could be nice.
I don't know yet what to use as driver. Could a 300B (with is separated power supply of course ^^) and choke loaded with 350v on the plate properly drive the GM-100 ? (or do I need something like a 845 or GM-70 ?) (I mean is it enought drive current and is 240V peak to peak swing (-120V bias) not too much for a 300B ?)

I was hopping to do full range with passive filter because my system have different impedances (HF more impedance than LF so no resistors would be needed ^^):
- 1.5 inch compression driver; 32 ohms; 109dB/1W/1m sensitivity (6000Hz-above)
- 10 inch horn; 16 ohms; 108dB/1W/1m sensitivity (180Hz- 6000Hz)
- 18 band pass horn; 8 ohms; 103dB/1W/1m sensitivity when alone 106.5dB/1w/1m when a stack of 4 (and 2ohms) (below-180Hz)

About the power that I need, of course at home in my smalll room, I don't need more than 0.1 watts (but I still don't know if a small DHT SET can properly drive big bass speakers =s (or if the speakers drive more the amp than the reverse ^^)).
But the system will be for to do outdoor parties (and I want to share with people the same technology that what I use at home) (currently I already have good class AB solid state amplifiers (I use only analog devices) but the feeling would probably have absolutely nothing to do with a full tube SET system).
Ideallly I would need 1800 watts power for bass (4*450 watts), And maybe for less than 800Kg and a budget of few thousand euros it seem to be dead ^^. So I would like to build the maximum output power SET for a maximum weight of arround 100Kg.

05-30-2018

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	14
Post ID:	24902
Reply to:	24901

It might be not right forum for you.

devo_yan wrote:
I should use at least 2 amplifiers (one for high frequencies and the GM-100 amp for low frequencies) with a tubes active filter at the inputs of each amps.

Yes, you might, though I am not a huge proponent of active filters and they are just not necessary active state, unless you go for high order crossovers, then it is a mistake in my view. There is another thing. The bi-amping does not work well if you have different amps with different sound. How to make the low power amps that would have the same dynamic and harmonic signature as your GM-100 amp will do I do not know. I for sure would use the same drivers but there is so much more to it…

devo_yan wrote:
This is what DSET mean, right ?

DSET is a Dedicated SET, the architecture where a SET is optimized for a given frequency range. There is plenty about it at my site.

devo_yan wrote:
I don't know yet what to use as driver. Could a 300B (with is separated power supply of course ^^) and choke loaded with 350v on the plate properly drive the GM-100 ? (or do I need something like a 845 or GM-70 ?) (I mean is it enought drive current and is 240V peak to peak swing (-120V bias) not too much for a 300B ?)

I am sorry, I cannot help you with this.

devo_yan wrote:
About the power that I need, of course at home in my smalll room, I don't need more than 0.1 watts (but I still don't know if a small DHT SET can properly drive big bass speakers =s (or if the speakers drive more the amp than the reverse ^^)).

The 845, 211, GM70 or anything like this will be more than sufficient for LF DSET.

devo_yan wrote:
But the system will be for to do outdoor parties (and I want to share with people the same technology that what I use at home) (currently I already have good class AB solid state amplifiers (I use only analog devices) but the feeling would probably have absolutely nothing to do with a full tube SET system). Ideallly I would need 1800 watts power for bass (4*450 watts), And maybe for less than 800Kg and a budget of few thousand euros it seem to be dead ^^. So I would like to build the maximum output power SET for a maximum weight of arround 100Kg.

If you want to entertain people for outdoor parties and need 1800 watts power then you are well outside of the means and competency of this site.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

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