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Horn-Loaded Speakers
Topic: AudioProjekte CA10

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Posted by Romy the Cat on 12-09-2009
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Anybody who ever tried SS amp with compressions drivers or the drivers of high-sensitivity that can be driven by minimum current knows how it works. Nelson Pass created with his First Watt project a lot of publicity to the idea. A few watts, in pure class A and in single-ended mode - it might be interesting. I say it “might” because I just do not know – I never had one. I still would like to hear a few watt single-ended VFET SS amp – not one does them…

A few days ago Reinhard from Germany mention another attribute of the same idea: Jean Hiraga’s "Le Monstre".

http://www.tcaas.btinternet.co.uk/hiraga.htm

You can go for the home page of the sites and will see a few other des of low power SS amps.

http://www.tcaas.btinternet.co.uk/

I do not partially care about the PP amps to drive soft magnets drivers but it might work. Unfortunately I never ever heard the people who use low power SS amplification to talk about Sound. So, if you know about any commentaries about Sound from the folks who use SS single-ended amps that have no feedback and drive with them over 105dB sensitivity then please post the link. Please discard the cases when people drive “yellow” drivers or those moronic full-range drivers.

The Cat

Posted by Romy the Cat on 12-09-2009
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There is a German company VALVET High-End Amplification and they do a little 10 watter Single-Ended amp.

http://www.valvet.de/en/bricks/e1/

There are few similar to this.  What is not clear is if they use caps in path and if they use feedback. I think by playing with the transistor itself and the biasing ways it would be possible to change sound of this thing…. Again, no one talks about the Sound of those things – they claim it to be “clean” and “transparent”. It is very much might be so but in my definition of Sound “clean” and “transparent” are not indicative entries.  Distil water is “clean” and “transparent” but you would not use it what you are thirsty….

The reason I brought the VALVET company is because they make own speaker that looks like use a compression driver (I do not know what they use)

http://www.valvet.de/en/loudspeaker/pulseon/

So, the might not be so dead in assessment of what their Single-Ended amp would do with the first watt.

The Cat

Posted by coops on 12-10-2009
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Mainly because of my young daughter I have been listening to mostly solid state amps, I have enjoyed 'Digital DoMain's' B1-a VFET, and am now listening to a German 'Audioprojeckte' CA10, 10 watt class A design, ( I will post a link later as their site appears to be down ) , I have  also ordered a pass labs 'First Watt'  J2 which  should be here soon.
It is refeshing to hear something new, I would recommend it.
Keith.

Posted by Markus on 12-10-2009
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http://www.audioprojekte.de/html/kits_en.html

Posted by coops on 12-10-2009
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Thanks Markus, have you heard it, TW recommended it ,and it is a superb little amp, after the CA10 valves seem a little blurry. regards Keith.

Posted by Romy the Cat on 12-10-2009
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 coops wrote:
Mainly because of my young daughter I have been listening to mostly solid state amps, I have enjoyed 'Digital DoMain's' B1-a VFET, and am now listening to a German 'Audioprojeckte' CA10, 10 watt class A design, ( I will post a link later as their site appears to be down ) , I have  also ordered a pass labs 'First Watt'  J2 which  should be here soon. It is refeshing to hear something new, I would recommend it.

Keith, again this BS?

I created this thread explicitly in horn section because I do not want to see taking about amplifiers, to see uploaded enumeration of links, 3 –word sentences  and certainly I would like do not read anybody’s “recommendations”. I was asking about the thoughts and commentaries about Sound of those amps with compression driver. Keith if you have no own thoughts about Sound or the ways to express those thoughts then can you stay fucking away from my site? Find for yourself another avenue to spread the anesthetized recommendation and numb posts.

The caT

Posted by Saturntube on 12-10-2009
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I have just taken out of my system a First Watt F5 clone Tim Rawson amp, It was substituted by a Telefunken PP amp with 6AQ5 tubes.

Let me to explain.

My system consists of 6 way horn loaded speakers.  I have a round Tactrix upperbass horn with 8" cone driver going from around 180hz up to 800 hz, then a compression driver from 800hz to 6khz and horn tweeter and supertweeter.  My bass modules are sealed cabinets amplified separately by SS subamps (soon to be changed).

I mainly use a pair of Leak TL12.1 amps with passive preamp to drive de Horn module from 180hz and up.  This horn module has a speaker level Xover.

I am trying now to use multi amps in order to achieve more transparency and dynamics, one amp for each driver, for this I need to add an active preamp.  After adding the new active preamp my Leak amps had too much gain and the system started to shout a little.  So I changed the Leak amps for the First Watt F5 clone amp.  

The difference soundwise in this half range 180hz and up horn module between the Leak TL12.1 amps and the First watt F5 clone was big,  mainly the tonal balance is very different with the midrange sounding thin.  Highs were more extended but a bit unnatural, they sound less liquid and more in your face, The midrange is not rude or scratchy but it is not full and round, it also lacks the attack on piano notes the Leak amps have.

I guess the tonal balance can be readjusted at Xover level but this I will not do at the moment. 

I also have a Chipamp (Thorstens inverted design) I have used for the upperbass channel alone and I remember it sounded very good in that range, The amp is a bit more jumpy and thinner than the tube amps I tried and on the upperbass horn the sound did become more transparent and mixed better with the tube amps and compression drivers on top. This test I will try to run again this weekend.

The same Chipamp on the full horn module from 180hz and up sounded terrible with a scratchy midrange and dirty high range.

My plan is to use a pair of spudamps similar partially to the Melquiades amp for the compression driver 800hz to 6khz and for the tweeter and supertweeter, and try either the F5 amps or the chipamps for the upperbass horn.

I will leave the Leak amps for the bass modules and see how they perform there.

PS.  Johan in South Africa uses Firstwatt F3 amps for upperbass horn and tweeters,  his upperbass horn is loaded by a JBL compression driver,  not a cone driver. 


Posted by Romy the Cat on 12-10-2009
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 Saturntube wrote:
The difference soundwise in this half range 180hz and up horn module between the Leak TL12.1 amps and the First watt F5 clone was big,  mainly the tonal balance is very different with the midrange sounding thin.  Highs were more extended but a bit unnatural, they sound less liquid and more in your face, The midrange is not rude or scratchy but it is not full and round, it also lacks the attack on piano notes the Leak amps have. 

Saturntube,

In context of your post a few things is needed to be to reviewed:

1)    What magnet types of your MF drivers and tweeter? It is my long observation that PP amps are very bad for driver with Alnico driver, they usually eat all details. The ceramic drivers however, that are ordinary are horrible for HF, are very nicely work with PP amps…

2)      What do you think, if you cone to use the First watt F5 and if you would be interested to recuperate some of the “midrange sounding thin” then would be able to do it with driving your upperbass with a slightly more open upper bound?

3)      The First Watt F5 is not truly the amp for consideration as it is not a single-ended amp.  Mr. Pass was progressive with his first amps - single-ended not feedback and then with his late model he become acting like a Moron who just read a lecture about conversion to vegetarianism and then stuffing himself with pepperoni on his elevator ride down to garage…

The Cat

Posted by cv on 12-10-2009
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Hi Romy,
On my to-do list is a single ended version of the F5... essentially just the upper or lower half of the schematic, with a load resistor to opposite power rail (or perhaps a low DCR SE transformer) replacing the complementary portion.

Alas it's quite far down the list of stuff at the moment, but I suspect that with battery supply and very careful, possibly 3d layout, it could be something quite special. I wanted to source the semisouth SiC FETs to try but not much cash at the mo....

I also think that a feedback path that short and direct is nothing to fear; even have Vishay Z foils to try in that position... eventually...

If you fancy trying a version with n channel JFET and the recommended Fairchild P-mosfet, I can mail you a couple of each to play with.

cheers






Posted by Saturntube on 12-10-2009
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Romy,
The upper bass horn has a Ceramic driver 18sound 8M400,  the MF horn has an 18sound 2060A Neodymium magnet, tweeter is Beyma Ceramic driver and supertweeter is Fostex Alnico.  The Leak amps are PP deep class A, we do have a couple of Audio Note P4 PSE amps I am not very fond of,  maybe it has to do with the ceramic magnets indeed.  


My upper bass horn has a very specific range which is where I am using it, outside of that range, even if fed the full range, it drops like a brick, minus 10 db,  the response looks like a pair of breasts with slight peaks (1 db) at 250 hz and 500 hz.   I could play around with volume,  mainly lower the volume of the compression driver and tweeters since the upperbass horn is run direct with no Lpad,  but I dont think I will use the F5 in this configuration.

I feel the upper bass is not fully tied in with the MF compression drivers,  I dont feel the instruments are free enough, there seems to be some haze when going down in freq, changing to the 8M400 helped in the upper register but we did loose some bass response against the prior 10" driver.  I hope the SS amps will help with the final details in integration, other wise I will have to change the driver again.  As you probably know adjusting the back chamber of a cone driver in a horn is a bitch, so I am mostly looking at Compression drivers that can go low.
I have quoted the JBL drivers 2490H with ceramic magnets and plan to test them down to 200 hz,  but I have to test the Radian 950 I already have on the big horn (140 hz) first,  that should be interesting.

Funny thing the supertweeters helped with the integration of the upperbass.


We bought the F5 amp to try out as either a tweeter amp, given its extended response, for upperbass as something more refined than the chip amps, or to substitute one of the subwoofer plate amps so we can play around with xover signal in the bass,  say Xover the midbass drivers up to 300 hz.


I will get back to you after some more experiments have been run.


Jorge

Posted by el`Ol on 12-11-2009
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 Romy the Cat wrote:
It is my long observation that PP amps are very bad for driver with Alnico driver, they usually eat all details. The ceramic drivers however, that are ordinary are horrible for HF, are very nicely work with PP amps…


Hello Romy,

have you searched for explainations for these observations? Are there others who made the same observations and tried to explain them? Does the damping factor play a role?
From my limited experience I can say that a SS PP amp doesn´t eat details in combinations with this driver (obviously ceramic, but why two demodulation rings?) Apart from the details (comparable to vacuum tube / alnico) I find that there is more control/precision/stability, so is it the damping factor that plays a role?
http://img502.imageshack.us/img502/1025/basil5.jpg

Posted by Romy the Cat on 12-12-2009
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 el`Ol wrote:
Hello Romy, have you searched for explainations for these observations? Are there others who made the same observations and tried to explain them? Does the damping factor play a role?
From my limited experience I can say that a SS PP amp doesn´t eat details in combinations with this driver (obviously ceramic, but why two demodulation rings?) Apart from the details (comparable to vacuum tube / alnico) I find that there is more control/precision/stability, so is it the damping factor that plays a role?

Nope, I do not know anybody ever made such a claim and I have no explanation for it. Put in this way – I was not looking for an explanation. To me any “explanations” in audio are interested only as long they address my practical interests. Since I do not use for HF any drivers that are made with ceramic then I see no reasons to look deeper into the PP/ceramic compliance. I am a practitioner and I am very much not in the Moronic realm of the Lynn Olsons whom writes 34534 “War and Peace” books about a single fart that their VIRTUAL loudspeaker and VIRTUAL result.

Yes, in a way the “eating details” might not be a perfect description of the phenomena. The ceramic drivers at HF have not details deficiency but different type of the details. If we compare drivers with dog’s surface (fear, fire, fur, fair - I can’t spell this fucking word!) then Alnico sound like a dry, long-hear dog. The ceramic is the same dog with a wet skin – the shape is there but this [fear, fire, fur, fair] does not stick out.

I discovered this phenomenon in 2000-2002 when I was doing over a LOT of compression drivers, in fact I was buying all possible driver to try. In that time as was driving everything with Lamm ML2.0. Many ceramic drivers did not sound very exiting – in fact it was truly trashy sound.  One day I was drying it with Lamm M1.1 SS push-pull and I was very surprised how wonderful it was. I made a conclusion that it might be pattern in it. Sure in all my following experiments I got significantly and predictably better results driving ferrite and ceramic driver with SS push-pull.

Was it damping factor in play? Hm, I do not think so. The damping factor is a fact what you have a EMF (electro-moving force) returned from the driver. To have it the driver shall have excursion and powerful inductive coil. In case of compression driver there is no EMF returned back to amp, it is like a ribbon – an amp do not care about the drivers reactive existence.   It might be not the “damping factor” itself but the way how the high damping factor is accomplished in SS PP amps. That is a whole another subject and do not feel equipped to think about it. Do not forget that compression drivers are driver with ultra low currant. I use 100 mV for my 16R driver. So any conversations about problems with sound around the crossover distortions in PP amps might be negligible if you drive 15” roofer but what the amp outputs 1/8 watt and 1/10000 of the nominal gain then those “little things” become too critical…

Anyhow, with SS amp and compression driver I would never consider any PP amp and would experiment ONLY with single-ended SS amp, but it is me. What the purpose to use PP – to make the ferrite driver to sound better? Let do not use bad driver to begin with and it would not demand us to “fix” them with PP amplification….

The Cat

Posted by vizion on 04-12-2010
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hi coops,Have you evaulated the J2 and AudioProjekte amps yet ?thanks.Eric

Posted by coops on 04-12-2010
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Eric Hi, this isn't the place, try both in your system if you can, Keith.

Posted by Romy the Cat on 11-08-2010
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Here is another amp from Germany

http://www.audioprojekte.de/html/ca10en.html

10W, class A, might be good to drive compression drivers. What is missing is that it not said if it is PP or single ended. It looks look like it has 2 power transistors:

 http://www.audioprojekte.de/CA10c.jpg

.... but looking at the traces on the board one of the transistors looks like some kind of PS regulator. (I can’t open PDF file)  From another hand if it is a single-ended design then the hit think is too small for 10W. Sure, if  it is PP then it is not interesting even to try but if it is single-ended and if it sits deep in class  A at full 10W then it might be fun to try it.

The Cat

Posted by jessie.dazzle on 11-08-2010
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Romy wrote:
"... I can’t open PDF file..."

Here's the part of the Manual that covers design features and specs (no circuit diagram available):

Introduction
The CA10 is a 10 watts per channel Class-A stereo power amplifier capable of great musicality and
realism.The amplifier is able to reproduce the body and soul of music like some of the good vintage
designs, but also achieves fidelity characteristics of modern devices.
And in deed, parts of the CA10 circuitry are based on the classical topologies of the 60ies and 70ies
of the previous century. Other parts of the circuitry are typically modern style.
The mixture of modern and classical topologies in conjunction with carefully selected transistors and
their appropriate points of operation leads to a different sound pattern than usually found in solid
state amplifiers.

Design Features
Measured/Matched Semiconductors: All semiconductors used in the CA10 are measured to
certain criteria. This is very time consuming, but necessary to achieve the intended performance
of the amplifier.
 
Selection of Parts
The CA10 uses the best sounding and quality parts available regardless of
costs. All components have been auditioned for performance and consistency in endless listening
tests.

Low Noise Power Supply
The power supply of the amplifier is divided into two sections. The
first part is built from an encapsulated toroidal transformer followed by a 35 ampere bridge rectifier
and a large C-R-C filter. The second part of the power supply is an active regulated on-board
circuitry with excellent transient response and a deep ripple suppression (-120dB!).
Slow Turn On Sequence: The CA10 has no sound sophisticating relays in the outputs. To prevent
turn-on thumps the operating voltage is risen slowly (20sec.) by the power supply.
Connecting a delicate driver directly to the outputs should not present any hazard.
In case the source is still playing music while the amp has been switched off, you can still hear more
or less distorted music. That is normal and the price one has to pay for the absence of a relay.

Specifications
Voltage Gain: 24 dB
Input Sensitivity: 0.55 V
Output Power: 10 Watts/ch 8 Ohms; 8 Watts/ch 4 Ohms
Frequency Response: -3dB at 5 Hz, 150 kHz
Distortion: (1kHz) < 0.02% at 1 Watt, 8 Ohms (mainly 2. harmonics)
Input Impedance: 100 kOhms
Internal Resistance: < 200 mOhms
Output Noise: < 1 mV, unweighted, DC-100 kHz
DC Offset: < 5 mV
Power Consumption: 150 Watts continuous
Measurements: 17.7" W x 13.4" D x 5.5" H (450x340x140mm)
Weight: 32 lb (14.5kg)

jd*

Posted by el`Ol on 11-08-2010
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This would also be interesting to try for someone who isn't afraid of trannies.

http://www.susan-parker.co.uk/zeus-se-amp.htm

Posted by Romy the Cat on 11-09-2010
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Yes, I do know some people who advocated that after a transistor output stage it shall be 1:1 transformer. According to them the transformer cleans up the bad residuals of SS and enrich signal with something. I do not know how to relate to this, I have no opinion nether about the transformer in the end of SS amp nor about the low wattage SS amps.

I still would like the manufacturers inform if their amps are PP, SRPP or a full single tact amps. I would also would like the people who test those low power SS amps to understand that SS amps react differently to the magnet type of their drivers. I wrote about it many types but it looks that it did not become a public knowledge.

The Cat

Posted by rickmcinnis on 11-09-2010
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And you are right that it also has a regulator within the power supply.  This is stated within the owner's manual but it would not allow me to copy it.  They use rather convoluted language.  Maybe this is the result of translation?

To quote from the review (I hope this is O.K.)
The CA10's input stage with current feedback is formed by a resistively loaded single bipolar transistor (the current driving the input transitor varies with the output signal and is used for the feedback loop). The voltage gain stage runs another bipolar part with a constant current source fixed to a low-noise voltage reference. The single-ended output stage runs two bipolars, one for gain, one as load. Circuit gain is a high 24dB, input sensitivity a concomitant very high 0.55V. Bandwidth at -3dB is 5Hz to 150kHz. Input impedance is 100k, internal resistance below 200mΩ. Output noise is below 1mV unweighted from DC to 100kHz, DC offset less than 5mV. Dimensions are 17.7 x 13.4 x 5.5" WxDxH, weight is 32lb. There are no sound-degrading output relays but the power supply deliberately scales up the voltage over 20 seconds to prevent turn-on transients. Fragile high-efficiency drivers are thus deliberately protected. The absence of relays of course also means no hard shut-down. Turning the amp off means music will continue for a few seconds, fade, then progressively distort before evaporating to mute.

There seem to be a few of them for sale on the used market.

You assessment of this kind of thing would be interesting since most of us have nothing quite like your set-up to make assessments with.

Cordially,




Posted by twogoodears on 11-12-2010
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Hi Roman, hi all... intriguing post and interesting questions, as I've been for about 20 years a triode and, before, a tube user and a glowing-in-the-dark maniac.

My experience...

I purchased - years ago - an Hiraga 20W which I used as a bass enclosure amp when (badly) multiamping with Pioneer D-23, and I loved the Altec 416A punch with such an amp; then I put on a shelf for a couple years, while I used Partridge/300B SET monoblocks, preferring their romantic musicality, from time to time I tried to use the above mentioned 20W Class A, BUT what I remember was "poor musicality" - i.e. listening fatigue, bleached, innatural dynamics and harmonics... I moved in and out of my system at least two-three times.

... so I gave up...

Nonetheless, in the meantime, I purchased for nice prices one more Class A 20W, then another one and finally The Mighty 30W Le Classè A, the most expensive (back in the late '70s) and sought-after Hiraga/Lectron's class A power amplifier, with its 1,5 Farads, a beast made in extremely low numbers... finally, I purchased a Le Monstre 8W for peanuts, also impessively sporting 0,7 Farads (consider the 0,5 Farads of 20W Class A).
It was a frenzy, as I sort-of became a traitor of triodes... my friends didn't waved hello, anymore, when meeting in the street;-) - BUT also a great chance to obtain those "fabled" perfect squares from cartridge/tape/live radiowaves/disks to horns.

During the recent, first days of October, overhauling and measurements to my speakers system, looking forward to the new bass horns in the making (poor me...), Franz Hinterlehner wanted to measure ALL my amps to know their sensitivities and that's why I had ALL my power amps, triodes and solid-states, handy.

Next step was to put in use the old Goto CF-1 3rd order fixed frequencies electronic crossover, 220/1000/5000hz... so, why not, we connected all that mess and... must say in the bad grounds loops and cable mess, I recognized a gem of sound;-)
Like from crap comes a flower...

When I was quiet enough and lonely, I optimized ground and... wasn't able to understand what happened to my little studio and the sound coming from Gotorama: it was ALL like when using SET monoblocks for the four ways, only MUCH, MUCH better: voilà, gone that annoying sense of coldness and innaturality, sound also after two full weeks without music, is still so well carved in my aural memory: smooth, liquid, full of lively harmonics, absolutely uncompressed and easy to the ear.

I was hitting me for such a late trial with (good) solid state... just before the flood (thanks to His Bobness for lending this;-)) I was having multiple orgasms, as virtually all disks and discs I listened to with FULL solid state multiamping was a double shot of same fix... I mean had to re-listen to same disc/k(s) twice to re-enjoy this... beauty.

So: where was the compression and sense of inadequacy I previously experienced with a single Class A 20W?

I cannot reply... boundaries between ESP and electronics are dangerous when put together... anyway, someone wrote about "blurred" sound when talking about triodes... must say, regretfully, I agree.

Every note now owns its own life and sparkling light and... it's both new and old sensation... like "ohhhhh, finally at home" stuff...

I planned, when mud-free again, to re-listen to a friend system using a mix of PP triodes (300B) and class D and T-amps with his large Onken/Altec/TAD/Goto speakers... I don't remember he obtained such a result - i.e. full class A cure as I'm using now - so, maybe it's a matter of interaction, balance and common sonic footprint... the most technical oriented (not me, my fault...) will find more apt explanation(s).

Sure is my satisfaction... maybe a flawlessly measured square waves at oscilloscope isn't so unmusical to the ear, don't you?

P.S. - when I first listened to Le Classè A 30W with a single speakers Zeiss Ikon/Klangfilm when I turned OFF amp, music continued, unaltered for about 90 seconds... then suddently dimmed...   
 


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