[penance]

Hi, long time no post.

I'm running a DV10x5 with my coronet and feel it needs a little bit more gain.
Pre amp is turned up quite high to get decent sound at the mo.
The DV puts out 2.5mv, valves are Mullard apart from Mazda rectifier.

Is there a simple way of getting a little more gain from the coronet?

[Theo]

I'm also running a 10x5 on my Cornet.  To me it sounds best with 8dB gain and 1K Ohm loading.  You will need a step up device, either a step up transformer or a headamp such as a Piccolo.  The last thing you want to do would be to modify the Cornet whenever you change cartridge.  I found my Piccolo very flexible for many cartridges and sounds great!

[analog97]

Interesting post.  Traditional wisdom seems to be you should not need any extra gain.  However, a friend and I just violated this rule by using the 12db gain from the PICCOLO to boost a 1.6 mv Denon 160.  We also used 1K loading and found a HUGE improvement.  My experience, although limited, suggestions some caution when relying on typical gain-calculations and let your ears be the final arbiter.  In our trial, the gain calculator suggested about 45db gain to be ideal, but clearly it was not and 56db gain for the 1.6mv Denon was supremely rewarding.  My suggestion is to second the PICCOLO vote by Theo and change the resistors in the low-gain PICCOLO slot to, say 6-8db.  Good luck and let us know what you find out.

[amandarae]

At 2.5 mV to a 44 dB gain(CornetII), you will have ~400 mV output to the main preamp.  I think this is too low.  If you have a step up or a head amp that adds 14 dB more (1:5) gain, then the result will be ~2 V(1.98 V) at the main preamp, same output as most CD players and should be more than enough and probably , you will not reach the midpoint of your main preamp volume control.

IMO.

[analog97]

Abe,

2 volts seems a bit high to me, although I've never tried it.  I am finding it near optimal to shoot for about 1 volt.  Using a low-noise device like the PICCOLO to send about 1 volt to the pre-amp produces FAR less noise at equivalent SPL's compared to just cranking the amp/pre-amp to compensate for a weak signal, say 300 mv.  So far, in my rigs, that seems to hold up very well and FAR better than the "common" wisdom I was referring to.  See below a quote from the KABusa website.  IMHO, 300-400 millivolts is too little voltage to present to the pre-amp.  Just does not seem to "light it up"....

The optimum gain is based on achieving 325mV rms output at 5 cm/s. For the current crop of CD recorders, 300mV is required for 0dB recording level with the recorder's level control set at max. Aiming for 325mV gives a little margin.

[Theo]

From my Piccolo I tried 6, 8 and 12 dB boost on 10x5's 2.2mV output.  You have the right idea.  Although I don't hear distortion on any of the boost levels, at 8dB I hear a bit less background noise on my Castanet at 3/4 volume than 12dB on Castanet at 2/3 volume.  I also tried 6dB but then I needed to almost clank to full volume.  I settled on 8dB so there is headroom when some recordings need it.

Common wisdom seldom prevail in this hobby and often disproved by experiments.  Piccolo encourages experiments on boost and loading.  A step up transformer may sound better for some cartridges but a Piccolo is a great tool for easily dial in optimal setting.

Abe,

2 volts seems a bit high to me, although I've never tried it.  I am finding it near optimal to shoot for about 1 volt.  Using a low-noise device like the PICCOLO to send about 1 volt to the pre-amp produces FAR less noise at equivalent SPL's compared to just cranking the amp/pre-amp to compensate for a weak signal, say 300 mv.  So far, in my rigs, that seems to hold up very well and FAR better than the "common" wisdom I was referring to.  See below a quote from the KABusa website.  IMHO, 300-400 millivolts is too little voltage to present to the pre-amp.  Just does not seem to "light it up"....

[penance]

Thanks guys, seems you agree with my thoughts.
Had always thought the DV10 was a bit low for the Cornet. Had a forced abstinance from vinyl due to room change and damaged arm. Got it all set up again a month or so back and decided I needed to sort this issue.

Reason i asked about gain change to Cornet, currently using the original cornet but have a part built Cornet 2 nearing completion. Wondered if it would be something easy to do while completing the build.

Must admit, the Piccolo would be a much better idea, funds wont allow at the moment (new house purchase).
Will carry on as is and get a Piccolo on the go when i can spare the cash.

[Bill Epstein]

Back when I had a DV 10x5 I ran it right into the Cornet, no problem, but my rigs have always been tube SET and hi-efficiency speakers.

Right now I'm running my .5mV Sonata directly into the Cornet2, one click away from 0 dB attenuation. With 8 watts and 97dB speakers there's a smidge of hum but otherwise sounds great.

Not ideal but I sold my oh-so-flexible Nova Phenomena when the newest Cornet was done, the switchable gain Cinemag can't cope with the 47k Grado and my Piccolo suddenly decided to go tits up.

Am I allowed to say both my low output Sonata and Ace are for sale as I'm getting a high output Sonata to run direct to the Cornet? The absence of step-ups and too many ICs is the new Dolce Vita

And for those of you scoring at home, I think the Jantzen Superior Z-caps at the output are a winner

[roger15ohm]

Hai guys, 

I am new here from Malaysia.  I just bought the basic board from JH and waiting enxiously to receive it.  Anyway I consider myself still new in tt world.  This topic Cornet gain is one of my concern in my setup.

Currently setup with Sumiko Pearl (4mv output), arm rewire with Cardas 33aw.  Phono plug out from spoit Sansui intergraded amp, I am not sure about the db of the phono-transistor type. Pre is Canary 601 and ST70 with VTA board, trioded.  Volume range of 1/4 to 2/3 to go loud but anything more will distort. 

I need more advise because I really plan to build in a V.control in the phono and direct driving the power.  I am not sure with Cornet 43 db is enough to do so since some of the post here a 2mv cart is driving low.  2mv vs 4mv is pretty near compare to my ex REga Bias at 7mv.  My next cart should be 103 but if gain matching is a problem here, then it will get worse.

Buying any mc is not in plan now except completing Cornet asap once in hand. 

Is there anyway to mod the circult? or increase/decrease any of the resistors works here?  Or anything to be done in the Cornet input stage?

Many thanks,

Wan

[danlaudionut]

Here is what I did for more gain.
I changed the output stage to GC.
Replaced the 220R with a 200H choke.
40uFd bypass on the 15K resistor.
Take the output off the plate.
.68uFd cap coupled to output RCA
with a 1Meg to ground.
Simple and almost the same gain as my CD.

DanL

[GRD]

I use a Shure V15 with 2.5mv output with the Cornet.  My amplifier is an integrated Classe CAP 150.  I find in my setup a little lower input voltage works well.  My CD player has 1 volt output and the Cornet requires a little more gain (or less attenuation).  However, I have gain to burn -  the amp section is 1 volt sensitivity and the preamp has well over 10 Db of gain.  I expect that I'm still using the volume control as an attenuator for most of my listening with the Cornet.

[roger15ohm]

Dan.

Thanks for sharing.  But, isn't that quite a major modification?  Dont mind to share your modded picture here?  Does it affect the original sound?

Wht is GC?
Which 220r you replace?  the power supply?


GRD

Likewise we do agree on high power amp sometimes works much better in passive pre. Sadly My ST70 modded only comes to 15watt driving my Roger 3/5a 11ohm.  week knees..


Like amandarae did high light on 2.5mv cart wth a 44 db phono equals 400mv, and 2.5mv cart plus 14db(mc) and 44 db phono equals 2v, which is very sufficient to drive a passive pre loud.  How about my current Sumiko Pearl at 4mv with 44db Cornet?  Anybody knows the formula?



Best regards,


Wan.

[danlaudionut]

Wan

Here's the first version of the schematic.
http://www.integracoustics.com/images/DanL/OCTAL_CORNET.GIF
Replace R6 with the 200H choke.
GC is Grounded Cathode
CF is Cathode Follower
This schematic is before I went absurd
on the PS trying to eliminate a 1Hz LF
instability that annoyed me   
I have a cLC/2K/2-150V  VR Tubes
then 1 LC per stage.
Now it's quiet as a dead church mouse.
AND there is no LF oscillation at last.
I am a Happy Camper again

DanL

PS It isn't a major modification.
The circuit is the same.
Replace a resistor with a choke
and add a bypass capacitor and
take the output from the plate
instead of the cathode.
The PS I have just helps it to achieve
every last bit of performance out of it.
Also the output impedance goes from
~400 to ~8K but driving a 100K load
then that is almost irrelevant.

[roger15ohm]

danlaudionut,

Hey,,, that was quite a major mod for me!!  Yet i never try 6sn7 before, and i still don't have one.  Very detail schematic!!!with Shinko res??? Isn't that expensive??  I'd got my board already; thanks for the tunder speed delivery all the way from Hawaii.  But the parts are still sailing in. 

I will plan to start with original circult, but using my existing power supply, Kt66 as stabalizer and rectify on 5ar4 too.  Power caps support with Cerafine 220x2 450 plus a double c core trans.  I bought this for my ex clone CAT pre.  It was sold off but left this with me. 

Don't mind to give a hand here, for the  B+ listed on the board -365v,  what was it before loading?  I want to rebuild the power supply to accomodate the Cornet2.

Best regards,

Wan.

[danlaudionut]

Wan

The PS was originally 325V.
You need to lower that B+.
Send me a schematic of your PS
and I can let you know what to change
to lower the B+ and keep it working right.

DanL

[roger15ohm]

DanL.

You mean supplying to C103? or  R107?  Thanks alot......

I don't think i still remember the schematic and the psu was sent to my guru for modding just hours ago.  I will try my best to draw it. 

Luckily the main tran still have 275 tapping, save my coins but the filament was 20v.  So it can only supply for rectifier and high tension.  It looks like the psu can do it's job but we have to rewind one more trans for supplying H+.

Thanks DanL.

[roger15ohm]

DanL.

The Psu just completed.  B+ is around 3 hundred plus according to guru.  I am yet to measure it.  Filament still ac at 7v direct from main trans (Grey and orange).  Anyway most importantly I can use the psu and save alot of money.  I hope the picture can tell you how the schematic looks like. 

At least 1st half is almost complete.  Still waiting the parts from partconnecxion. 

Re:   I will try to draw the schematic later but i don't know the resistors color coding. 


regards,

Wan

[danlaudionut]

Wan

This is an easy color code converter -
http://www.ealnet.com/m-eal/resistor/resistor.htm

DanL