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Topic: Gain calculation and LCR advantage

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Posted by Romy the Cat on 07-11-2007

Keith Cooper mentioned today the AllnicAudio’s 1500 phonostage in the Cessaro thread…

http://www.allnicaudio.com/E/e_pdt_ampli_H-1500%20II%20SE.html

I know the AllnicAudio, I use their tube sockets, and they are very good.  The AllnicAudio uses a pair of 417A for their phonostage. I am not a big fun of those tubes and 600R load for those little pentodes is too much but still it very much might be a good phone corrector.

The AllnicAudio in thir web site point out some shortcomings of different correction topologies – very superficially and they are not completely correct unfortunately. Regardless of it the subject of the LCR EQ is very interesting. I have one and I do like it a lot, although my personal “reference” corrector is not the LCR type.

Thorsten have eaten a dog on the LCR subject and his 7788 corrector was very good. I changed it for 7788-7721 and it was even better. I heard that Thorsten made the 10K LCR filter that should be very interesting but I did not follow the subject very close for years and I found “other solution” to deals with the problem of the constantly recharging feedback capacitors.

Another attractive company did a few years back a very interesting LCR phonocorrectors. It was the DaVinciAudio from Switzerland. In their initials version it was very cool but I heard nowadays they went for it’s commercial version, hugely simplified….

http://www.da-vinci-audio.com/Grandezza/grandezza.htm

I still generally very welcoming the LCR correctors, I wish it was more of them. There are a dozen companies about which I heard that do them. The Thorsten’s approach with 7788 at input is the more appealing to me (7788 has better sound and lower noise, particularly if to play with screen’s supply) but the 7788/E810F is not a tube that have any mass-commercial potential and therefore it is overlooked by the manufactures who dream to become a second BAT.

Anyhow, here is the Korean’s AllnicAudio attempt around the 417A/5842… I wonder if they paralleled the input tubes to drive the low impedance LCR filter?

Where are those 80dB of gains with my 2 stages only????!!!

The caT

Posted by Romy the Cat on 08-13-2007

a Hong Kong-based company DIY Hifi Supply is selling RIAA EQ modules, the first modulesthat I have seen at 10kOm. It is something that Thorsten did not do commercially… but if the silks sound good then it might be VERY interesting. Is anyone knows anything about this company and about those modules? The 7788 with 10K load will be VERY cool thing to try….
 
http://www.diyhifisupply.com/diyhs_magnetics.htm

The caT

Posted by coops on 08-13-2007
I heard the 'cole' LCR phono by the hifi supply recently at a friends house and it sounded ok, the Allnic 1500 that  I am using at the moment is the best phono I have heard, and the price is extremely reasonable for the design, valve regulated power supply etc. Did you manage to get in touch with MR Park ? Regards Keith.

Posted by Romy the Cat on 08-13-2007
It is not about the LCR phono as a concept – many companies manufacture the RIAA LCR constant impedance networks: Lundahl, Tango, S&B, Da Vinci, A-D, your Allnic looks like dose them as well. The LCR filter is not complex and any manufacturing house that does magnetics should be able to do it. However, whoever did it so far made the LCR filters with impedance of 600R. If you are wiling to make 2 stage phonocorrector with LCR filter between then the best sounding high-gain tubes available out there would not feel very comfy to drive 600R. The reported beauty of that Silk LCR is that it has 10K impedance and it would be a perfect load to any ultra-high-transconductance input tube…

Posted by Paul S on 08-13-2007

I have read about but not heard the transformer RIAAs and the "No R" version (or was it "no C"?), and I have seen some fairly ingenious ways to try to keep impedance at a constant 600 Ohms.  But the 10k does pique my interest, because now we have the slack to make a real-life, semi-flexible gain stage that might not mess up the RIAA values.  Maybe stand off the tubes with diodes?  Hybrid cascode?

I can do OK with ~40 dB net, so two stages still seems like the reality, and probably the usual "sandwich", with the RIAA between the gain stages.  I don't get one gain stage.  Why/how would you do that, unless you just fed the signal to another gain box?

I'd like to try something like 1/2 of  a 6SN7, with that tone, but less going on internally.

The Da Vinci looks very cool, but I ass-u-me it's priced for punters only, didn't even check the price.

Lord knows, I need a few more transformers in my signal path...  another topic perhaps, but probably germane to this topic.

Best regards,
Paul S


Posted by Celloman on 10-03-2007
Hello Coops,

Can you explain more why the Allnic 1500 is the best phono you have heard, and why was it superior to the Cole LCR ?

What is the superiority of LCR-RIAA phonostages , besides having excellent RIAA correction curves ? What about their dynamic abilities (macro nd nuances), timbres, resolution and fluidity ?

Thanks.

Posted by coops on 10-03-2007
Cello HI  I have only heard the Cole for a short time, so it wouldn't be fair to compare, also I really can't say to what extent the LCR circuit contributes to the sound of the 1500, the Allnic is very dynamic, has high resolution and makes instruments sound more like instruments , I am using the head amp with it at the moment and it is super, really super, worth a listen and not  high-end expensiveeeeeeeee.

Posted by Romy the Cat on 10-03-2007
 coops wrote:
Cello HI  I have only heard the Cole for a short time, so it wouldn't be fair to compare, also I really can't say to what extent the LCR circuit contributes to the sound of the 1500, the Allnic is very dynamic, has high resolution and makes instruments sound more like instruments , I am using the head amp with it at the moment and it is super, really super, worth a listen and not  high-end expensiveeeeeeeee.
Coops,

it looks like you are repeating what you did in the Cessaro thread, staring without any rationale, in your posts the following: “Cessaro is the best speaker in the world”. Sure, you are perfectly entitled to do so, but for the sake of sanity you should mention that you are a reseller who trade Cessaro Horn and ALLNIC electronics. BTW, I have a guy live next door who works as a salesperson in Circuit City. His job is 8 hours per day to convince the visitors that the voice of God is transmitting to humans via a Yamaha receive…Do you want to argue with him? I do not question your message but I would like the messages to be delivered in a lucid framework.

Rgs, Romy the Cat

Posted by coops on 10-03-2007
Romy Hi, I only represent  Cessaro in the UK now  because I  honestly believe in them, I don't represent any other makes or manufacturers, Ralph introduced me to Allnic ( he had tracked down the designer Mr Park )we compared the amps to the usual suspects Zanden Wavac Air Tight etc and the Allnics were speedier had more punch and better resolution, can't sell them even if I wanted to because they havent passed the European CE compliance legislation , I am ceretainly not going to bang on about them on your forum, I do think Mr Park  has some interesting designs which are properly realised ,and the amps offer a lot for their relatively reasonable cost. Keith.

Posted by Romy the Cat on 10-03-2007
 coops wrote:
Romy Hi, I only represent  Cessaro in the UK now  because I  honestly believe in them, I don't represent any other makes or manufacturers, Ralph introduced me to Allnic ( he had tracked down the designer Mr Park )we compared the amps to the usual suspects Zanden Wavac Air Tight etc and the Allnics were speedier had more punch and better resolution, can't sell them even if I wanted to because they havent passed the European CE compliance legislation , I am ceretainly not going to bang on about them on your forum, I do think Mr Park  has some interesting designs which are properly realised ,and the amps offer a lot for their relatively reasonable cost. Keith.
Keith, I do not think that I prohibited to anyone to “bang on” about anything, please do so. Be prepared also to deal with consequences if you do it at level of religious subscription or a professional loyally. I would be nice if you inform up front that you are the product’s representative. Also, be advised that so far you said nothing nether about Allnic nor about Cessaro. As a regional rep you might as well repeat what you was told by your world wide rep…

Posted by coops on 10-04-2007
Romy Hi, there is nothing to say really, I was trudging up the usual hifi route, ( B&W 800's usual high powered solid state amps Wink I thought a turntable upgrade would be the last step! Went to GT Audio to listen to Thomas Woschnicks turntable, gt is the UK Avantgarde distributor, I hadn't heard horns before there was something immediate about them, I liked very much, I posted a question on a UK forum, Guy Sargeant ( who occasionally posts here ) advised me to check out Cessaro , i wrote to Ralph kreabs ( Mr Cessaro )  Thomas Woschnick invited me over to Germany , I  didn't know but Thomas had met Ralph two years previously , heard Ralph's Gamma's and really thought them superb, he said he couldn't sleep for a week1 Ralph agreed to design a smaller speaker for Thomas' room , I didn't realise the as well as hearing Thomas' turntables I would also be listening to the Alpha horns. Ralph also visited that weekend he bought the first piece of Allnic the 1500 phono, which we compared with Thomas' resident phono stage. Thomas has a great system the speakers sounded wonderful, I decided to buy a pair on the spot, sold my B&W's the next day. Ralph said he would make a pair for the Munich Hi-end show and we could bring them back to the UK together, Ralph just wanted someone who really liked the speaker to represent them ,rather than the usual dealer who will sell anything if the margin is big enough. Having heard Ralph's system ( gamma ) I would buy them in a moment but although I might be able to afford the speakers I can't afford a house in London big enough to put them in!
Yours sincerely,Keith.

Posted by Romy the Cat on 10-04-2007

Keith,

I do not know why you go crazzy over it. All that is necessary is juts to mention that you are distributing given audio equipment and it would be it….

Anyhow, the Alnick RCL phonostage, the H-1500 II SE one, do you know anything about it? It has 3 WE417A tube per channel and it looks like a follower. The WE417A are high gain (If I am not mistaken 30 times) and 3 stages can easily do 66dB. Dose Alnick use all 417A as gain stages or they parallel them to drive low impedance RCL filter? In such case do they use a step up transformer to get MC gain? If they do use transformers then who made for them the magnetics? Is any further topological information is available on the Alnick unit? What is the retail price for the H-1500 II SE correctors?  Also, since given corrector is MKII then what was in the MKI? And the last thing. How people can try this phonostage?

Rgs, Romy

Posted by coops on 10-04-2007
Romy Hi, I just didn't want you to think that i was just another hifi dealer , I just really liked the speakers, re the Allnics innards I will forward your question  to  Ralph at Cessaro he is the international distributor, I do know that Mr Park winds all his own transformers including the LCR modules, the 1500 with valve regulated supply retails in the UK for approx £2500 , Jeff catalano may be handling them in the US, he is in New York ,Highwater Sounds, very best wishes,Keith. 

Posted by Paul S on 10-04-2007
Coops, this thread is sort of long considering we still haven't gotten anything about your own personal impressions of the sound of any of the gear you have chosen.  Even if your objective was only to announce/generate interest in the gear - and I am not saying that this is the case - as of yet there has been naught from you that gives a good sense of what you are talking about in the only terms that really matter to a listener, namely the sound.  Some technical info is always nice to help digest the impressions, and some context is pretty important, too, if you can and will.

Surely you can use descriptors other than superlatives to share your impressions of this stuff?  Also, when you went from your former gear to this gear, what were your specific reasons?  It would sure be nice if you would compare and contrast.

Usually "exotic" gear sellers take one of two approaches: either "The Rob Report" - an all out blitz that includes great photography and purple prose from drooling reviewers, momentos for seekers; or, there is the "Try To Find Us" approach, which seems always to inspire uncontrollable lust in a pretty predictable percentage of the punters.  When you popped up, I hoped that you might be more forthcoming and informative, since your products do appear superficially interesting.

Best regards,
Paul S

Posted by coops on 10-04-2007
Paul Hi, I don't consider myself a dealer, just an enthusiast, I just wanted to discover just what was possible with audio replay, Thomas Woschnicks system (whee i first heard the Alpha's ) was just more real more like real life than anything I had before, the sound was more immediate, living breathing real. Horns as you know excite the air in the room, the bass is more like a double bass' bass breathing, in comparison the B&W's sounded incredibly boxy, the sound emanating from two points, the sound wa veiled and dull, just as though a potato sack had been thrown over the speaker. When we first installed the Alpha's I was runnnig them with an ASR Emitter a large German SS integrated, it had been fine with the B&W's but it sounded flat and lifeless withthe horns. I started to look at valve amps, Thomas W uses  a KR 1610 power amp , the Alpha's aren't that efficient  98db ( the bigger cessaro's are much more efficient ) . Ralph suggested I try the Allnics, and so far i haven't heard anything better, in fact tsome of the 'big names' have been rather disappointing nice casework though!
I was fortunate enough to spend the week at the Munich hi end show, and after a few days at Ralph's listening to his Gamma's , which are like the Alpha's but just more! Pleas if you have any specific questions drop Ralph a line through the Cessaro website, he is fanatical about music .

Posted by Romy the Cat on 10-15-2009
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Recently I was visiting a guy who has Alnic H-1500 LCR Phono stage. I actually had a chance to open it up and to inspect it.

http://www.allnicaudio.com/eng/products/view.htm?brandcode=0010040000000002&page=1

I would say that I like what I saw and how it sounded. It was not might playback and I do not know if it truly did what I would like a Phonostage to do but the initial superficial feel was very positive. The Alnic H-1500 has a pair of paralleled 417A driving output stage. I did not trace which the E282F of 417A in input and which is used as driver. It would be fun if the Alnic’s LCR would be high impedance then the input stage would drive the filter directly, skipping the driver stage all together.

Nevertheless it looks like an interesting phonostage. Too bad I do not care about phonostage anymore or I would bring it home to try…

The Cat

Posted by montepilot on 10-16-2009
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Romy,  why not get this guy's phono stage to try so we all can benefit from an unbiased opinion of its performance?

Rgs,

montepilot

Posted by coops on 10-16-2009
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David beetles is the US distributor, I am sure he would send you one for evaluation, 'hammertone audio' get him to send you the head amp too, that is also worth a listen.Keith.

Posted by Romy the Cat on 10-16-2009
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Thanks, Keith and Montepilot.

I did have my 7788-7721 phonostage with LCR filter and I always liked it, pay attention - it was 68dB gains with just two stages and with NO step-up transformer.  Allnic  Phono is 3 stages with step-up transformer. Still Allnic might be a good phonostage but I see no personal motivation to “evaluate” it. It is not become I feel anything is wrong with Allnic. I just have a phonostage that I feel comfortable and I have zero itch to look for anything else.

The Cat

Posted by perrew on 10-16-2009
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Romy,one thing that interest me is you use an active RIAA and the Allnic is passive circuit if I understood things?

Posted by Romy the Cat on 10-16-2009
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 perrew wrote:
Romy,one thing that interest me is you use an active RIAA and the Allnic is passive circuit if I understood things?

Perrew,

Among the none-commercial, home-made correctors here is my evolution of phonostages.

1)    EAR-384PT - dual mono rebuilt with Thorsten medications

2)    7788-7721 – with Thorsten-made LRC filter.

3)    EAR-384PT-AIR  – with air capacitors

4)    7788-7721-AIR  with air capacitors and EAR-like feedback

I need to say the all 4 of them sound very nice, but the EAR-384PT-AIR, bundle with SU-2 step-up transformer made my “End of the Life Phonostage”.

http://www.romythecat.com/EndOfLifePhonostage.aspx

I had no problem with 7788-7721, ether the LRC or with EAR-style feedback, but I feel that Expressive Technology SU-2 transformer works better with EAR input tube and sound more pliable all together.

I need to say that what Alnic at their site linked above made comparing of different RIAA methods: (from the Alnic's site)

"Active filters (Negative feedback type)

Different quantity of negative feedback applied.  Deeper feedback to high frequencies and shallower to low frequencies. Improved S/N Ratio, low cost and consistent operation. Looser bass reproduction and possible a pinched and compressed high frequency playback due to excess feedback ratios.

Passive filters (CR type)

The frequencies filtered to fit that of the RIAA by varying the amount of attenuation at different frequencies through a complex resistor-capacitor network.    No voltage overload, purer reproduction form no feedback, and more accurate RIAA compensation.  No gain, insertion loss and impedance matching problems.

Hybrid filters (CR and Nega type)

Use of two type filters to low and high frequencies separately (Active filter to low frequencies and passive to high frequencies). The advantages and disadvantages of two types shown up at the same time.

LCR filters of H-1500 II SE

Two pieces of linear reactor (a kind of choke coil) comprises main parts, assisted  by precise RC filters to lower impedances and insertion loss. In vacuum tube circuits, active and passive filters usually are operated on hundred some kilo ohms of impedance, LCR RIAA filter's impedance is 600 ohms constant! Lower the impedance, more dynamic and more detailed reproduction.  Furthemore, LCR RIAA filter's series resistance, less than 13 ohms (Tango's 31 ohms)  But LCR RIAA unit drawbacks are high cost, difficulty of impedance matching which has been the hindrance of commercialization of superb unit and its phono amplifiers.   GIS KOREA LTD. manufactures itself the LCR RIAA Unit of high quality and develops the 600 ohms impedance matching method even without coupling transformer, Non-negative feedback circuit secures pure sound reproduction without coloration. "

The advantage of the passive LCR filtration that Alnic mention are correct it is not all that counts and there is other side of the medal. Still, I always liked the LCR phonostages and I feel that is one of the best way to go, despite that I do not use it.

The Cat

Posted by perrew on 10-16-2009
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Romy,you seem to ascribe very much of your LP playbacks success to the Expressive Tech SU-2 superiority, maybe 50% from my own guess,so it must be a very nice step-up, you are one of the few that has any experience with it. There is one forum member that owns the Allnic H-1500s bigger brotherthe H-3000 and runs it together with a ET SU-1.Anyway I see some resemblance between the Allnic and your beloved Lamm LP2, at least they share the WE417 tubes (can at least be fitted with WE if not delivered with) but I guess the Lamm dont have the LCR. So would you say LCR is the key here?

Posted by Romy the Cat on 10-16-2009
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Perrew,

I do not know if you use sarcasm in there but Lamm LP2 is not my bellowed phonostage. In fact I am one of the very few people whop do not like it at all. How much in what I do not like in Lamm LP2’s MM section come from the WE417 tubes? It is hard to say. I am not inclined to blame the tube just because a unit with it turned out did not perform up to my level of demands. The type of problem I hear from Lamm LP2 might come from anything. So, I do not necessary associate my bad LP2 experience with WE417. I feel that LCR is the key element in Alnic phonostage. Also, Alnic has one extra stage around E282F, so electronically it might be whatever you can imagine. Alnic also looks like parallels the output stages with WE417. Lamm with a single WE417 has 3.5K output impedance – remarkably high. Alnic shall have twice lover. Alnic said that it has 430R but it is most likely BS and I would trust to Lamm specification – he always very accurate with specification. Alnic might use output stage as some kind of follower but I doubt and the need some gain after the LCR. I am not a big fun to parallel tubes but it is what they do.

I looked at the H-3000 phonostage specification. It might be fun to run it with ET magnetics. The H-3000 according to Alnic has two stages of amplification – it is how it shell be. However, it has just 66dB gain not enough for most cases. Alnic used my 7721 for both stages, most likely first as pentode and second as triode. I did the same with 7788 in the first stage. It was if I am not mistaken and still remember 55DB from the first stage and 33db from the second stage, the 20dB was eaten by RIAA and I end up with 68dB of total gain…

Anyhow, the LCR correctors with good quality of LCR filters are fun. That DaVinci LCR phonostage from Switzerland shall be interesting as well, at list the early versions 10 year back, when they made it one by one to order. I afraid that nowadays, when they have publicity, market share and distribution chains DaVinci might do the mass-market crap as anybody else…

The Cat

Posted by Romy the Cat on 10-18-2009
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It is not a the thread about Allnic but LCR RIAA correctors, still there was something expressed in here about the Allnic LCR phonocorrector… and  I feel bad about it. It is not that I don’t think that Allnic LCR phonocorrector deserve positive mentioning.  Furthermore, I heard recently Allnic MC cartridge that I also liked. The problem that I have is that a remarkable amount of idiots visit my site, stupidly search for the brands that they want to buy and use this site (and many other sites) and a guidance for some kind of audio “recommendations”. I can’t stress how much I hate it and how I am bored I with those people. I invests effort do not any explicit reconditions at my site. Still, I got for the last few days emails from the site visiting Morons asking me if I fell that Allnic phonocorrector is better than two other phonocorrector and if I think that they need to buy it. What the idiots!

Anyhow, to offset my positive comments about Allnic phono I am harry to inform you that Minority is not alien to Allnic. I local guy own Allnic preamp that sounded like shit. Ok, I need to tell you that it did not sound like a bad sounding preamp – it sound worse. Regardless what you feel in the preams it out 10dB of dynamic range – I am not exaggerating – it converted the whole spectra of sound into one octave wide of 10dB range and it was it. I was mocking the preamp owner and proposed him to throw this preamp into the head of the idiot who was responsible for this sound.

The Allnic’s preamp is just one stage transformer-coupled buffer – how complex shall it be? We opened up the unit and the very first think that shocked me was that Allnic used my phonostage’s 7788 tube as driver for the preamp.  The 7788 tube that used for microphone preamp and MC cartridges, the tube that has 0.5V bias and no ability to drive anything, Allnic used to be fed from line-level input signal, that might saving as high as 2-3V. Can you pretend what would happen indirect heated signal time you drive with signal 6 times more then it’s bias? It is not class “B” operation anymore but the class “F”, as an abbreviation from the “Fucked operation”. Funny  that the Allnic web site say that preamp use 7721 tube, the one that I used in my phonocorrectors output:

http://www.allnicaudio.com/eng/products/view.htm?brandcode=0010030000000003&page=1

The 7721 is a driver tube with 1.7V on grid; it is still low but already something. Also the 7721 can driver some load. Replacing the stupid in this location 7788 to the 7721 did “fixed” the preamp.

Now the interesting question: how the hell the 7788 made into the Allnic’s preamp?  The guy who owns the preamp bought it brand ne and never opened it up.  It is not to mention that he just a user who does not know or care what is the difference between volt and ampere – he is highly not technical and very far from the nuts and bolts of audio.  The Allnic designer would hardly made this mistake – you need to be a completely idiot to use 7788 as a driver – the Allnic designer doe not strike me as an idiot. The distributor who sold the unit would also hardly make the substitute: the 7788 is twice more expensive and those industry primps would kill themselves for extra saving, it is not to mention that they are in most cases are too audio-retarded to do anything with hands or brain.  So, how the 7788 made into the Allnic preamp?

I did a courtesy call to the Allnic distributor informing him that I have in my hands a horribly performing brand new unit and I see that it uses 7788 tube as a driver. Instead of expressing regrets and proposing overnight the right tubes to fix the unit the Moron begin to question my assessment of the sound with 7788 and proposed me to talk with the designer.   Why do I need to talk with the designer – to confirm that the distributor is a dupe who has no idea what he sells? Oh, such a classified information!!!

Anyhow, I think I am too hard on the poor Allnic people.  It is most likely not their fault and the customers with screwed sound is not their liability. It is most likely the UPS people sting in this brown track, opening the Allnic units and replace the tubes. Nevertheless, if you do like the Allnic phonostage then you need to open it up and to confirm that Allnic did not use the 845 tube in input gain stage – they can as my experience shows…

The Cat

Posted by Romy the Cat on 10-27-2009
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 Romy the Cat wrote:

It is not a the thread about Allnic but LCR RIAA correctors, still there was something expressed in here about the Allnic LCR phonocorrector… and  I feel bad about it. It is not that I don’t think that Allnic LCR phonocorrector deserve positive mentioning.  Furthermore, I heard recently Allnic MC cartridge that I also liked. The problem that I have is that a remarkable amount of idiots visit my site, stupidly search for the brands that they want to buy and use this site (and many other sites) and a guidance for some kind of audio “recommendations”. I can’t stress how much I hate it and how I am bored I with those people. I invests effort do not any explicit reconditions at my site. Still, I got for the last few days emails from the site visiting Morons asking me if I fell that Allnic phonocorrector is better than two other phonocorrector and if I think that they need to buy it. What the idiots!

Anyhow, to offset my positive comments about Allnic phono I am harry to inform you that Minority is not alien to Allnic. I local guy own Allnic preamp that sounded like shit. Ok, I need to tell you that it did not sound like a bad sounding preamp – it sound worse. Regardless what you feel in the preams it out 10dB of dynamic range – I am not exaggerating – it converted the whole spectra of sound into one octave wide of 10dB range and it was it. I was mocking the preamp owner and proposed him to throw this preamp into the head of the idiot who was responsible for this sound.

The Allnic’s preamp is just one stage transformer-coupled buffer – how complex shall it be? We opened up the unit and the very first think that shocked me was that Allnic used my phonostage’s 7788 tube as driver for the preamp.  The 7788 tube that used for microphone preamp and MC cartridges, the tube that has 0.5V bias and no ability to drive anything, Allnic used to be fed from line-level input signal, that might saving as high as 2-3V. Can you pretend what would happen indirect heated signal time you drive with signal 6 times more then it’s bias? It is not class “B” operation anymore but the class “F”, as an abbreviation from the “Fucked operation”. Funny  that the Allnic web site say that preamp use 7721 tube, the one that I used in my phonocorrectors output:

http://www.allnicaudio.com/eng/products/view.htm?brandcode=0010030000000003&page=1

The 7721 is a driver tube with 1.7V on grid; it is still low but already something. Also the 7721 can driver some load. Replacing the stupid in this location 7788 to the 7721 did “fixed” the preamp.

Now the interesting question: how the hell the 7788 made into the Allnic’s preamp?  The guy who owns the preamp bought it brand ne and never opened it up.  It is not to mention that he just a user who does not know or care what is the difference between volt and ampere – he is highly not technical and very far from the nuts and bolts of audio.  The Allnic designer would hardly made this mistake – you need to be a completely idiot to use 7788 as a driver – the Allnic designer doe not strike me as an idiot. The distributor who sold the unit would also hardly make the substitute: the 7788 is twice more expensive and those industry primps would kill themselves for extra saving, it is not to mention that they are in most cases are too audio-retarded to do anything with hands or brain.  So, how the 7788 made into the Allnic preamp?

I did a courtesy call to the Allnic distributor informing him that I have in my hands a horribly performing brand new unit and I see that it uses 7788 tube as a driver. Instead of expressing regrets and proposing overnight the right tubes to fix the unit the Moron begin to question my assessment of the sound with 7788 and proposed me to talk with the designer.   Why do I need to talk with the designer – to confirm that the distributor is a dupe who has no idea what he sells? Oh, such a classified information!!!

Anyhow, I think I am too hard on the poor Allnic people.  It is most likely not their fault and the customers with screwed sound is not their liability. It is most likely the UPS people sting in this brown track, opening the Allnic units and replace the tubes. Nevertheless, if you do like the Allnic phonostage then you need to open it up and to confirm that Allnic did not use the 845 tube in input gain stage – they can as my experience shows…

Again it has nothing to do with LCR RIAA correctors but since I brought the subject of the Alnic preamp in this thread I feel I need to follow it up. I have a story with Alnic preamp that still can’t interpret.  Not that I care too much but I think for sake of truthfulness I need to tell the whole story and all that I think about it.

In the post above where I was blaming Alnic for use 7788 with .5V on grid was not absolutely accurate. I spoke with the Alnic designer who informed me that 7788 use as a triode with 3.5V on grid. I do not remember that in my case 7788 has 3.5V but I think it was 1.7V but I would not insist that I am right. If you wish to see how 7788 behave as a Triode then look here - there is plenty of data.

http://www.diyaudio.com/forums/tubes-valves/102393-7788-triode-curves.html

According to Alnic designer the 7788 were not made in his preamp accidently but was substituted because according to Alnic it “sounds better”. I very much disagree with Mr. Park – he feels that 7788 is a wonderful driver. I do not like the 7788 as a driver it has no current - who need such a driver. It is difficult to dispute anything with Mr. Park as he overly polite .  Also, I did not particularly cared about Mr. Park’s “theory” as I has right in my home his Preamp with 7788 and 7721 and what I heard was beyond any need to debate. Mr. Park was trying to present the differences as “personal preferences” but it was very far from it. Playing the preamp with 7788 has dynamic range of 15dB and it no needs to talk furthers a about any preferences. The 7721 did wipe out the problem, making the Alnic’s Preamp to sound acceptable.

I need to make very clear that I very much do NOT supports the Alnic’s idea about the transformer coupling. The advantages that Alnic’s enumerated at this site:

http://www.allnicaudio.com/eng/products/view.htm?brandcode=0010030000000003&page=1

I would call very controversial and in many case I would not agree with them. I would not debate it here just will mention that the transformer coupled preamps are very sensitive to the load impedance and it changes very dramatically harmonics of the output tube. I loaded Alnic’s Preamp to EVS attenuator and each click of it made the Alnic to sound differently. So, everything was clean – the 7788 was the Alnic’s mistake, the 7721 was fine. I can question that 7788 has more gain and the OPT ration for the 7721 and 7788 has to be different but… it is not might preamp to care too much.

The Mystery came next. The Alnic’s owner invited me in a few days as he bought more tubes and to do some other thing and he did listen the Alnic’s Preamp with different lording amps and different tubes again. THIS TIME the 7788 did not behave as bad as before and we fed the 7788 and 7721 with the same input voltage as before. There was still a difference between 7788 and 7721 and the 7721 was better but this time it was not day and high result and there was no compression to barbaric 15dB. I was sitting in there, listening, flipping the tubes like an idiot and was not able to understand why the difference that use to be so huge suddenly went to much less scale. I still have no explanation and I was not alone who witnessed it.

Anyhow, here is what I think I would do if I use the Alnic’s Preamp. Get rich the 7721 and 7788 and to put in there my 6E6P-DR in triode mode. The tube has very same pins and a full equivalent.  Increase the plate voltage to 200V. The 6E6P-DR is 8W driver it is a very powerful driver with 33 times gain. I would driver it with 22mV that would make it ~ 5W. I n this mode the 6E6P would have 1K on pals and the ratio of the transformer need to be adjusted accordingly – it looks like Alnic doe good transformers as it will not be hard for them….

Anyhow, it looks like Alnic’s Preamp  is very versatile unit and you can put in there many tubes… Still, I would not use the 7788….

The Cat

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