EV-1 Gain too high

[Mojofilter17]

My new (to me) EV-1 phono section seems really hot (gain, not temp). CJ specifies the gain at 49dB. I believe mine is producing something like 55dB, which is really blasting my PV-12 AUX input. Signal is loud at 7 O'clock, nearly distorting at 8 O'clock.
I'm running a Shure V15 III - output spec'd at 3.5mV. It's said to like a 47KOhm, 400pF load, which is the default setting for the EV-1.
At 1KHz (unity on the RIAA curve), a 3.5mVrms input into the EV-1 should produce just under 1Vrms output. I am getting about twice that.
I checked all the tubes for correct type, and swapped other KTBG tubes in - no change.
Any ideas on why the gain would be so high on the EV-1?

[admin]

Hard to tell which component is the cause of "too much volume",... cartridge, phono pre, preamp, amp, or some small contribution from each.

If you think the problem is really from the source/phono preamp section, you can try a phono signal attenuator.

[Mojofilter17]

Well - the issue certainly appears to be the EV-1 itself. With a lab-grade signal generator (Keysight 33600A) set at 1KHz, 3.5mVrms (the specified output of a Shure V15 III), the output of the EV-1 is 2.02Vrms (across 100KOhm resistor - specified input impedance of my PV-12) as read on my lab-grade AC volt meter (Agilent 34401A) - a gain of 55.23 dB. Exactly the same with both channels. This is much greater than the advertised 49 dB of the EV-1.

Just wondering if maybe the unit was modified for use with MC cartridge? Or is this a common problem? Perhaps someone has seen this before?

[admin]

You mention that the system is already loud at the 7 o'clock position on volume. A 6 db extra gain should not be such a dramatic amount even if the unit were out of spec.

[AnotherJohnson]

6dB is a quadrupling of perceived sound level.

Depending on the pot, it’s plausible.

[admin]

I thought 10 db more is "twice as loud" so 6 db would be less than that. I think the power to produce the sound is 4x for a 6 db increase but not actual loudness. Am I recalling these wrong, it's been awhile?

[Mojofilter17]

Just confirmed high gain with track 1 of the Analogue Production's 'The Utimate Ananlogue Test LP'. This is a 1KHz Reference level (0Vu) tone.
I measured 108mVrms on the output of the EV-1 (100KOhm load), with a 0.188mVrms input from the Shure V15 III.
So, dB = 20 LOG(Vout/Vin). A 55.19dB gain.

[AnotherJohnson]

This unit may have been modified to handle LOMC.

It is old.

The factory has been willing to make gain and load mods per customer requests literally for decades.

There may be nothing “wrong.”

It may be doing exactly what it has been modified to do.

[AnotherJohnson]

I thought 10 db more is "twice as loud" so 6 db would be less than that. I think the power to produce the sound is 4x for a 6 db increase but not actual loudness. Am I recalling these wrong, it's been awhile?

Here’s a good study.

http://www.sfu.ca/sonic-studio-webdav/A ... ctions.pdf

The truth is, it’s subjective, it’s frequency dependent, and there are physiological differences in play, complicating the subjectivity.

But 6 dB is pretty noticeable to any skilled listener.

Thomas Edison could fool people into thinking that there was a real orchestra behind the curtain, so the skilled listener issue is real.

In any event, my personal opinion is that this particular EV-1 has been modified to deliver the extra gain. 54 or 55 is a typical target for CJ without transformers.

[Mojofilter17]

Thanks! Any idea where these modifications might have been made? I am comparing the unit component values to the schematic and not finding any changes - i.e. resistor values, modified circuit traces, etc. Not finding anything.

The only thing I notice is that the 150K plate resistors for the 5751 tube are not VTA52 type resistors, but rather RN65s. But the value is 150K so I don't see how that could cause a gain change. A noise change, yes. BTW, tics me off that The VTAs are unavailable, and CJ won't sell me any!!

To get away from this issue of dB levels etc, I'll reiterate in explicit voltage values: The Shure V15 III is advertised to have an output of 3.5mVrms. A 3.5mVrms 1KHz signal at the inputs result in a 2.02 Vrms signal at the output. By my calculations that's about twice what it should be.

[AnotherJohnson]

There is no way to know.
CJ may have service records, but often they don’t.
I think it could well have been done at CJ.

I could be wrong, but over the years in discussions with the factory, such mods have been offered on other pieces under discussion.

FWIW, my TEA1 started life as a TEA1B with two equal 54 dB gain stages. It had the cap upgrade, which is not marked on the exterior, but for which there is supporting paperwork in my file. And it had transformers added to stage 1.

It does not presently reflect the gain values of a normal unmodified TEA1s1. Stage1 is 64 dB, and stage 2 is 54 dB. The transformer mod is noted on a dated label on the back of the unit. All the work was done at CJ.

If I ever sell it, the real specs will be duly noted. But that is only because I am the second owner and I know them. Many used pieces are sold with no service history.

[bschott]

Two questions come to mind - is your v15 actually putting out 3.5mv or could it be higher for some reason. Also, could V4 possibly have a 12ax7 stuck in there by mistake?

[AnotherJohnson]

Interesting idea and worth a look. I’ve thought that the V4 is an inverter, but the 12AX7 has 5 times the gain of the 12AU7.

Following your idea, maybe to reduce gain you could just put 5751s or 12AT7s in V1 and V2. Both are lower gain than the 12AX7, but otherwise close enough to be a substitute in the circuit.

[Big Dog RJ]

I believe what we have here is a classic case of cartridge output - phonostage mismatch.

What's happening here is the OP's cart is high output: 3.5mV is pretty high, in which case the phonostage should be one designed with low gain, not high gain. If the CJ phonostage is rated at 55dB this is high gain, which is more suited to low to medium output MC carts. Definitely not a cart that puts out 3.5mV! That'll go through the roof!

If you want to keep the CJ phonostage then change the cart to a much lower output rating, somewhere in the range of 0.8 to 1.5mV will suit much better. This is the similar gain structure I'm currently using with my Benz Micro Glider SM, medium output (0.8mV) with CJ's TEA2SE Max at 55dB, which is high gain.

The Benz M Glider has three variants in the S series:
SL (low output) = 0.4
SM (medium output) = 0.8
SH (high output) = 2.4

Yours is 3.5mV...!!! And you're using a phonostage with 55dB gain, I'm surprised you've still got the roof intact! Let alone the speakers... should have blown off by now.

If you want to keep the cart then I'm afraid you need to find a suitable phonostage with much lower gain or one that has selectable switching, like the Rega Aria or Cyrus phono-preamps. These are excellent phono-preamps with a wide selection of gain settings. CJ's phonostages are not very versatile...

It's very important to get the gain structure right, a few mV off or too high gain settings, can set the whole structure out of whack! This is why you are experiencing very loud playback leading to distortion, definitely not good for music.

Hope it goes well, all the best
RJ

[roberto]

My new (to me) EV-1 phono section seems really hot (gain, not temp). CJ specifies the gain at 49dB. I believe mine is producing something like 55dB, which is really blasting my PV-12 AUX input. Signal is loud at 7 O'clock, nearly distorting at 8 O'clock.
I'm running a Shure V15 III - output spec'd at 3.5mV. It's said to like a 47KOhm, 400pF load, which is the default setting for the EV-1.
At 1KHz (unity on the RIAA curve), a 3.5mVrms input into the EV-1 should produce just under 1Vrms output. I am getting about twice that.
I checked all the tubes for correct type, and swapped other KTBG tubes in - no change.
Any ideas on why the gain would be so high on the EV-1?

Hola, try a low output MC cartridge. Yes, I know that you have the Shure. I asked the same question to the big chief, Mr. Jeff Fischel, and his response was: use a lower output cartridge.

There are MM cartridges with lower output than the Shure, I do recommend to you the Denon DL-103 MC. The sound of the MC cartridges is more accurate and also has crispy highs.

Just my 2 cents!

Happy listening!

[Big Dog RJ]

+1

Cheers, RJ

[AnotherJohnson]

Any ideas on why the gain would be so high on the EV-1?

This was the original question.

[AnotherJohnson]

Just confirmed high gain with track 1 of the Analogue Production's 'The Utimate Ananlogue Test LP'. This is a 1KHz Reference level (0Vu) tone.
I measured 108mVrms on the output of the EV-1 (100KOhm load), with a 0.188mVrms input from the Shure V15 III.
So, dB = 20 LOG(Vout/Vin). A 55.19dB gain.

As it evolved, the question didn’t really change.

[AnotherJohnson]

Obviously a lower output cartridge will match better with 55 dB of phono stage gain. For the Shure, 40 dB would have been better than 49 OR 55.

He probably bought the “new to him” EV1 because on paper it should have been an OK match for his Shure. So he was disappointed when it turned out that it was not a good match.

Sigh … one of the possible outcomes when buying older gear.

FWIW, I have some MM Shure and HOMC Denon cartridges here, but I only run them on the Dual record changer. I use the latest Shure but with their 78 rpm compatible stylus. Not a fan of either brand at this point, except for the price points.

[Music Matters]

I have had an EV1 from new for 21 years. It's designed to be used with cartridges from 0.4 to 1.0 ideally. I once contacted CJ in the past and they confirmed this to me as well. I have used it initially with clear audio moving magnet, then multiple benz glider MC's, then Ortofon Cadenza Blue MC, then the Benz gullwing SHR MC. I have found best in my system with the two Benz MC cartridges, which are 0.7 and 0.8. The Cadenza Blue also worked very well. The Ev1 has internal loading as well...for my system with the Benz gullwing SHR 47k sounds better as more dynamic. I agree with others...your cartridge is too high gain. Look for ones as CJ state...0.4-1.0. I personally wouldn't go below 0.5 due to noise, even though CJ state fine down to 0.4, but personally would be fine going over 1.0, but not too high! Hope that this helps.

Kind regards,

Graham