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Old 14th January 2003, 03:42 PM   #31
Joel is offline Joel  United States
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Perka,

a) You can get a good speaker for MUCH less than $5,000! I know the snobs will jump all over me, but Cerwin Vega's aren't half bad speakers, and they are 102dB efficient, and around $200 each.

b) Your "ideal" can (and should) change over time, and with experience. Writing off a topology, or speaker style is self-limiting.
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Old 14th January 2003, 05:23 PM   #32
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I'll gladly admit that Cerwin Vega are not bad for the money but is it fair to compare them to ProAc? A better amp and worse speaker may be a lateral move at best. I have had quite a few speakers (including CV ) and find that efficiency is often accompanied by colourations. Severe ones too. The possibility exists in my mind that a reasonably neutral high efficiency speaker exists but i've never encountered one. Let me admit that my experience with horns involves only Lowthers and these inevitably give me a headache after a short while. Headache notwithstanding, they have other absolutely great qualities. As a comromise it doesn't work for me though it clearly works for others.


cheers

peter
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Old 14th January 2003, 09:46 PM   #33
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Default LOWTHER

Hi,

Quote:
Let me admit that my experience with horns involves only Lowthers and these inevitably give me a headache after a short while.
The cones need some taming.
Have you tried damping it by applying some fluids (C37) ?

Aspirine helps too.

Cheers,
__________________
Frank
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Old 14th January 2003, 10:32 PM   #34
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Quote:
Originally posted by analog_sa
The possibility exists in my mind that a reasonably neutral high efficiency speaker exists but i've never encountered one. Let me admit that my experience with horns involves only Lowthers
Jeez Peter, don't write off horns and other high eff speakers because of some (presumably) rear loaded Lowthers. Yuk. Probably the very worst of the type. A modern design front loaded horn is stunning and very low in colouration, and extremely low in distortion compared to almost any DR, at a realistic level, and has dynamics throughout the range DRs can only dream of.

However, much as I dislike ProAcs (I owned some for years), buying a cheap pair of CVs is definitely a lateral move, at best. Some Tannoy Golds (or Reds if you're rich) or DMTs (100db/W) are a huge improvement in a decent box with a new crossover.
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Old 16th January 2003, 11:47 AM   #35
dhaen is offline dhaen  Europe
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Perka,

I suggest you consider cutting a deal with Mozfet for his PSE output transformers, for sale in the Trading Post:
Selling Audio Note OPTX 300B PSE

Cheers,
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Old 20th January 2003, 08:35 AM   #36
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After considering your doubts on my speaker efficiency, I better go for a more powerful design. I found that the Cary 805C must be close to what I'm looking for. I have done some searching but couldn't find any kits or drawings for this kind of design. Is this a very rare design?


" ....The CAD 805-C is a 50 Watt/channel Single-Ended Mono Block Amplifyer providing pure Class A triode power. The Tubes consist of a 6SL7 Input, a 300B Driver, a 845 Output, and a 1629 Power Indicator...."

Perka
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Old 20th January 2003, 09:01 AM   #37
dhaen is offline dhaen  Europe
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Hi Perka,

try this link:
http://www.ainamoi.com/805c.htm

I have a number of observations:

Very high voltages are used with these valves. Knowledge of high voltage work practice is essential.

It is a commercial product, as such, AFAIK the transformer specification is not available.

It uses global negative feedback. The use of G-NFB in a transformer coupled design is critically dependant on transformer specification.

What kind of watts? Even with the NFB, I do not believe it can output more than 30w, bearing in mind the supply voltage and cathode bias arrangement.

However, IMO the basic topology is good.
Of course I would say that, because It's very similar to my own OnRyoku design:
http://www.dhaen.org.uk/vdocs/onryoku.htm
You are welcome to take ideas from it if you want
I am adding information all the time....

Cheers,
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Old 20th January 2003, 09:15 AM   #38
dhaen is offline dhaen  Europe
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Perka,

I see you looked

213.64.160.103 - - [20/Jan/2003:10:10:12 +0000] "GET /vdocs/onryoku.htm
h103n1c1o1020.bredband.skanova.com


Let me know what you think...

Cheers,
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Old 21st January 2003, 10:40 AM   #39
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John,
Your 845 seems to be perfect for my needs!
As I understand it you are still evaluating the design and I'm waiting to see the final outcome.
I have a lot of soldering experience, but none in tube amplifiers, so the high voltage is scaring me a bit. I have done a lot of reading about this since two days, and it seems that even a lot of experienced builders got electric chocks of 700V. I understand it that un unexpected source of electric chocks is often remaining current in the capacitors even a long time after the power is cut.

Actually, because of this I also need a very easy to understand schematic and a step to step guide where to measure the different voltages and check that they are OK before I put in the tubes.

So one way to go could be to build a amplifier with less dangerous voltage just for the experience and fun and then proceed with your project.

What do you think about building the "300B PSE MK2 - Parallel Single Ended" by Andrea Ciuffoli. I know yoy refer to his 845 project at your homepage, so I guess you have confidence in his projects.

http://www.audiodesignguide.com/my/pse2.html

Even if I won't be able to enjoy high music volymes with my proacs, I guess this amplifier would be very good with certain kind of music like cello and female voices.

This project also have the advantage that I don't need a
preamplifier for the use with my cd player.

My second question is about the recommended Lundahl transfomers in "300B PSE MK2 - Parallel Single Ended". They seem to cost about 700usd. Is this very high quality transformers? Could I buy some cheaper ones at still good quality and in such case where do I find them? The reson I ask is that the total cost in this project seems to exceed the 1000pound for a finished kit like the one at worldaudiodesign.

Per
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Old 21st January 2003, 01:23 PM   #40
dhaen is offline dhaen  Europe
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Hi Perka,

Yes, I am fully satisfied with my 845SE amp, even though I'm still making refinements.
You are correct about the high voltages stored in the capacitors. The high voltages also cause extra problems with insulation compared with sub-600 volt equipment.

The "300B PSE MK2 - Parallel Single Ended" by Andrea Ciuffoli, looks interesting. I haven't studied it in any detail yet. I'm reasonably confident that the knows what he's doing - though all his "projects" seem to use large quantit'es of Lundahl transformers and chokes. I think he must be the local dealer
He certainly does give detailed construction information, though I've not used it.

One important thing to check, is the input sensitivity. You may need a preamplifier for some sources.

The Lunahl transformers are regarded as good quality. If you use other transformers, you must be careful about the choice.

Did you check on the link I gave you?
Selling Audio Note OPTX 300B PSE
This member is selling some output transformers made by "Audionote" that might be suitable. You should ask him the power rating and the primary impedance, if you are interested.

Cheers,
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