Phono Preamp Advice needed

the thin end of the wedge
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Miksailo
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Phono Preamp Advice needed

Post by Miksailo » 20 Sep 2019 20:56

Hi all!
Im having problems with upper midrange and highs in my sistem.
Tt is Systemdek IIX,
tonearm is Mayware Formula 4 mk2 with its own interconects from arm and
cart is Grado ZF1 with grado gold stylus.
Phono preamp is Korato made in Serbia, valves e81cc and two 6072/12ay7.
Which solid state would you guys recommend me for this setup.
Year ago ive had Luxman l430 integrated amplifier and its not problem with TT-arm-cart part, everything was fine, its more this tube preamp i beleive causing my “highs” probs.
Here is the youtube link, so if you guys have time for listen and help me, i’ll apreciate it a lot
https://youtu.be/Pc8Ce93evuM
Sorry for my bad English, hope you got the point

tlscapital
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Re: Phono Preamp Advice needed

Post by tlscapital » 21 Sep 2019 12:06

I know per se none of your gear. Listened to your YT clip, it does sound 'crisp' or 'bright' to almost 'brittle' in the highs leaving not much room for the mids and lows. Causing damage not only to the highs but to the whole "picture".

If such issue was not existing with you previous Luxman integrated amp I suspect a sort of mismatch between your preamp and cartridge. Is your preamp adjustable in load, gain and capacitance ?

Your cartridge is a MI (moving iron) one and maybe it requires better or proper matching in the above adjustment and I believe to perform optimistically a well balanced preampfification stage as well.

Maybe your Serbian preamp is of the "good" kind but intended for other cart like LOMC (?) and amplification if ever. There are good and affordable adjustable solid state preamp out there you might want to trial.

Miksailo
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Re: Phono Preamp Advice needed

Post by Miksailo » 21 Sep 2019 18:57

Ive listened my clip on other mobile phones and laptop and it sounds bright and like u have explain but the in real sound its not like that.
As i said, Luxman l430 was nice but a bit coloured and warm sound with great highs.
Also i tried Yamaha c60 preamp with built in phono, it was better than this tube preamp but didnt like the sound
This tube preamp was great on Shure m91 mgd and Dual 1234 turntable but in my system it plays so slow and “lifeless”.
Maybe someone with same cartridge like I have or similar Grados can recommend me some phono preamp that works fine with MI carts
Thanks!

Bob Dillon
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Re: Phono Preamp Advice needed

Post by Bob Dillon » 21 Sep 2019 19:44

A Parks Audio Puffin phono pre allows much adjustability to tailor the sound to your preference. You can do MM/MI/HOMC/LOMC or even ceramic cart :) with the Puffin.

The thing that most bothered me about that clip was how prominent the surface noise from the LP was - like a swimming pool sized bowl o' Rice Krispies. Maybe a synergy issue somewhere in the system ?

tlscapital
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Re: Phono Preamp Advice needed

Post by tlscapital » 23 Sep 2019 00:26

Miksailo wrote:
21 Sep 2019 18:57
Ive listened my clip on other mobile phones and laptop and it sounds bright and like u have explain but the in real sound its not like that.
As i said, Luxman l430 was nice but a bit coloured and warm sound with great highs.
Also i tried Yamaha c60 preamp with built in phono, it was better than this tube preamp but didnt like the sound
This tube preamp was great on Shure m91mgd and Dual 1234 turntable but in my system it plays so slow and “lifeless”.
Maybe someone with same cartridge like I have or similar Grados can recommend me some phono preamp that works fine with MI carts
Thanks!
The Shure M91 'MGD' compliance is quite high (35 !). Where the Dual '1234' tonearm seem to be of the medium toward heavy effective mass (up to 5 grams VTF with 10 grams cartridges). So although you find that match to work good with your tube preamp, the tonearm to cartridge resonance tells that this cart and tonearm are not a match... ...in theory at least. Mind you this equation is not bullet proof.

And your Mayware tonearm is of very light effective mass. Not that this could/should likely solve your actual problem, but if this Grado 'ZF1' is according to it's 1.5 recommend VTF so seemingly of high toward medium compliance, fitted on this light effective mass tonearm, you might want to try to swap it for the Shure M91 and hear how does that sound if ever... And then test the Grado on the Dual 'lifeless' turntable ;)

aardvarkash10
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Re: Phono Preamp Advice needed

Post by aardvarkash10 » 23 Sep 2019 01:37

five posts in and I still have no idea what the actual perceived sound problem is.

a better definition of "slow" and "lifeless" might be helpful.

tlscapital
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Re: Phono Preamp Advice needed

Post by tlscapital » 23 Sep 2019 09:33

aardvarkash10 wrote:
23 Sep 2019 01:37
five posts in and I still have no idea what the actual perceived sound problem is.

a better definition of "slow" and "lifeless" might be helpful.
This I believe could be the result of the very high compliant Shure M91 'MGD' cartridge on a medium toward heavy effective mass Dual tonearm. The suspension of the cantilever being completely "squashed" down the cartridge performance could sound' slow & lifeless'.

The Grado 'ZF1' cartridge should also benefit from some tonearm higher inertia. Although this might not addressed the OP issue but to swap the Dual turntable with the Systemdek and/or their respective fitted on cartridges should be at least in theory an improvement both ways.

]eep
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Re: Phono Preamp Advice needed

Post by ]eep » 24 Sep 2019 00:51

So I took the time to stream the video to my high end setup. But from what I heard I can't really tell if or what would be wrong. It sounded like a livingroom recording with nothing wrong, I heard bass, mid and treble but far away. So I have to go on what you described.

My first idea would be wrong matching. I think the tube phono-amp would be great, better than most solid state. But you need proper loading; resistance capacitance (try 200k io 47k?). If you can't solder try a different cartridge.

Or maybe you could ask the guy you bought the phono-amp from?

If I were in your shoes I wouldn't buy a different phono-amp just to try and fix a problem elsewhere. And if you don't know how to solder or modify this would be quite expensive for an uncertain outcome. It will most probably make things worse. Modern solid state phono-amps are very linear and quite unforgiving. Vintage (as in old) ones tend to sound slow and subdued (not much highs).

I just bought a duo box opamp based phono-amp from China that is just awesome with just one minor modification, but I really wouldn't advise it to you.

Oh, and if you are really serious about listening to vinyl, turn off the f-ing TV and PC. Those screens are really distracting. Especially the TV.

sturgus
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Re: Phono Preamp Advice needed

Post by sturgus » 24 Sep 2019 23:42

Have you thought about tube rolling the Karato? That is a very nice preamp. Two guys in our club have Karato preamps.

MCM_Fan
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Re: Phono Preamp Advice needed

Post by MCM_Fan » 25 Sep 2019 02:49

]eep wrote:
24 Sep 2019 00:51
My first idea would be wrong matching. I think the tube phono-amp would be great, better than most solid state. But you need proper loading; resistance capacitance (try 200k io 47k?).
I'm not familiar with the OP's exact model Grado cartridge, but I'm running a vintage Grado G2+ in my system and Marc Morin recommended dropping the input resistance from 47K to something in the 22 - 24K range. I made a pair of loading plugs with some 1/2 watt 47K ohm 1% metal film resistors I picked up locally. As usual Marc's advice was spot on. I'm listening to it now and it sounds great.

Loading plugs plus Y-cables makes it easy to custom tailor the input resistance of your phono preamp to match your cartridges. Much easier (and more "portable") than actually modifying your preamp. Great how-to article here:

http://daveyw.edsstuff.org/vinyl/loading/

I picked up a used kit DPB-6MC locally for a song:

https://store.acousticsounds.com/d/6004 ... ccessories

Obviously, made for moving coil cartridges, which I don't have. My amp (Yamaha A-1000) has the standard 47K input for MM carts, so I needed some parallel loading plugs and Y-splitters to drop the resistive loading into the desired 22K - 24K ohm range.

I was originally planning to make my own, but this kit had been listed for a while on my local craigslist, I called up the seller, made him an offer and he accepted it. I swung by my local Fry's and picked up some 1/2 watt 47K ohm metal film resistors, soldered them in one set of the plugs.

From the outside, it looks like the standard DB Systems DBP-6MC kit:

https://i.postimg.cc/GtJNc7GQ/DB-System ... -Kit-1.jpg

The only difference was soldering the 1/2 watt metal film 47K ohm resistors, which results in 23.5K ohm total resistance, in place of the original 1/4 watt carbon 20 ohm (no "K") resistors. I also have four more sets of plugs I can play around with in the future. Total cost for the (used) kit + 47K resistors = $16.49. The only drawback is under the color coded slip on caps are some hard black plastic threaded caps that screw onto the RCA plugs. DB Systems chose to glue these threaded black plastics caps in place. That makes dissembling them and changing the resistors a pain (no doubt intentional).

For anyone contemplating making their own parallel resistance plugs, I created the following tables based on the E24 decade table of standard resistor values:

https://audiokarma.org/forums/index.php ... g.1474535/

These tables assume a phono preamp with the (somewhat) standard input resistance of 47K Ohms.

As mentioned previously, the formula for parallel resistance is: Rtotal = 1/(1/R1 +1/R2). Easy enough, but these tables will save you opening a calculator and punching in some numbers.

For example, if your phono preamp has an input resistance of 47K ohm and you desire an input resistance of 32K Ohms, you would use 100K Ohm resistors in your DIY plugs.

Miksailo
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Re: Phono Preamp Advice needed

Post by Miksailo » 28 Sep 2019 15:30

Thank you all,
My problem is solved with new tubes, all changed and sound is dynamic with great extension in highs. Punch, slam, details, all came, even previous tubes were new, but werent “original” ones. Someone before me ( previous owner) changed them for some reason. I’ll make a video with same song with new tubes in a day and post again.
Again, thanks!!
P.S. TV is OFF now when plays music!

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