Thanks for the input so far. Well I assumed it was a gain issue because I have to turn the volume knob up to around 2 o'clock to get satisfactory listening levels. When I play CD's, the volume knob is around 10 o'clock for the same listening level. In my old preamp/amp setup, I did have to turn the phono up louder than the CDP, but it wasn't as drastic. Phono was about 11 o'clock, CD around 9 o'clock.
FWIW, previous amp was 75 wpc, the amp section in my current integrated amp is listed as 80 wpc.
Sidssp, the phono stage is solid state, and was not noisy in my old preamp/amp setup. It does seem like surface noise, but my cartridge, speakers, and phono stage have not changed. I sold my preamp and amp (both tubed), bought an integrated amp, then I noticed the change. CD's play with no noise issue. The integrated amp has a tube line stage and tube power amp sections.
Kal, where would I find V1 and V0?
Cheers,
John |
Ok, thank you for the responses. That does explain the volume difference to some extent. According to John's calculations, my phono stage has an output of 0.5V, while my CDP has an output of 2.5V. So, I'm guessing (since I can't find my old sceintific calculator) that I would need a cartridge with about a 2.0 mV output with 66 db of gain to make a closer match to the 2.5 V output of my CDP.
Is this correct? Or as Kal suggest, I should try changing the preamp tubes in the integrated amp? (1 12AX7, 1 12AU7)
Cheers,
John |
Hello John,
Thanks for the information. I'd love to hear the new Reference, but my life has changed quite a bit, and ultra high end hi-fi is no longer a part of it. I looked at the SSSS, but it was out of my price range now. I use a 2 meter run from my Walker phono stage to VAC integrated amp. A 2 meter run of Chinchilla was $550, I just traded my 2 meter XLO Sig 3 for it straight up. So obviously the Jade Reference is out of the question. I won't rule it out in the future, but right now, I can't foresee ever spending big $$$ on any audio stuff.
Speaking of Jade, they sure are hard to sell on the used market. I've had no luck selling my 2 meter balanced pair of Hybrid Gold for over a year now....even at a 60% loss. I guess I should just tear out the conductors and sell the gold.
Thanks again for your input, as always, it's very valuable.
Cheers,
John |
Thank you Doug, Kal and Al for your very informative replies. I think I have some ideas of were to head here. First let me make a few points of clarification. Kal, you are right, I looked it up, and the preamp stage in my integrated amp has 11 db more than the gain of my seperate preamp. So more gain may be a bad thing.
Secondly,I have owned this integrated for over a year now, but due to personal reasons, have not listened to analog for about the last 8-9 months. As I recall, the last I listened to this setup regularly, the noise was more apparent than with my seperates, but not nearly as loud as the noise floor is now. Doug, the noise sounds like surface noise, steady hiss, easily audible from the listening chair when I turn the volume up to my normal listening levels (70-90 db). Also thanks for the JJ tube reco Doug, I may try that.
Here are my current thoughts. First, my phono stage is the Walker Audio Signature. Walker recommends that the DC offset be adjusted monthly. When I had the rig running regularly, I checked it about every 3 months, no issues after the original adjustment. However, I have lost the manual, and can't recall how to adjust the DC offset using the supplied DMM. I sent Lloyd an e-mail yesterday and I'm awaiting a reply. I think I should check the DC offset before tube rolling. Second, once I have made sure the Walker phono preamp is in spec, if the issue still exists, change out the preamp tubes. As far as everyone has said, and I tend to agree, one of these two steps should solve my problem.
I do not expect a $6500 integrated amp to be as quiet as $20K seperates, but I do remember it being enjoyable before, so I should be able to make it enjoyable again for much less than buying a new cartridge or phono stage.
I'll keep you posted once I've heard Lloyd's reply. Thanks again for all of your help.
Cheers,
John
BTW, all cabling is single ended, not balanced. |
I'm sorry Kal, but I tend to agree with Al here. I'm already listening with the knob set at 2 o'clock on the VAC, I can't understand how lowering the cartridge voltage and/or phono stage gain would accomplish anything but make me turn the volume knob up to 4-5 o'clock. If the problem is the VAC preamp tubes this wouldn't seem to solve anything as far as I can understand.
I've owned this cartridge/phono preamp combination for about 3 years now. It was dead quiet with my ARC Ref 3 preamp. It was slightly noiser when I switched to the VAC Avatar Super (possibly due to the extra 11 db of gain) which I've been using for the last 15 months or so. I didn't listen to any LP's for about a 8-9 month time frame, and now the noise floor is much higher with the same players. I still think it's probably either the DC offset in the phono stage or a bad tube in the preamp stage of the VAC. It's certainly easier and cheaper to fiddle with the phono preamp and the preamp tubes than to buy another cartridge or phono preamp.
I guess as an answer to my original question, there is no table that shows how to convert cartridge output voltage in db gain, but you did show me a formula to use, and I thank you for that.
Thanks again, and happy holidays to all.
Cheers,
John |
Thank you Darkmoebius. Using this calculator, it looks like I would need a phono stage with 80 db of gain or a cartridge with a 1.25 mV output to match the 2.5 V output of my CDP in SPL.
My guess was at least 10 db difference, but now I know that there is a 14 db difference, which explains the different settings on the volume control knob.
Still awaiting Lloyd's reply. I guess with the holidays and all I shouldn't hold my breath.
Cheers,
John |
Kal, please note the word OR between 1.25 mV cartridge output and 80 db gain phono preamp in my previous post.
Darkmoebius and Al, actually that link shows that my integrated amp is a VAC Avatar Super, NOT the SE version. Your specs are correct for the SE version, the Super is different. The only spec I can find on the Super is the 80 wpc output in ultra-liniear (no triode option). The Super does use different preamp tubes, different driver tubes, and different power tubes. So I don't think I can use the SE gain specs.
My Walker Signature phono stage specs the same as the Reference, and is set for the max gain of 66 db. According to the calculator that Darkmoebius provided, my 0.24 mV cartridge with 66 db of gain outputs a signal of 0.48 V. That would explain the difference in my volume control knob positioning, since my CDP output is 2.5 V, over 5 times the output of the phono stage. Both signals pass through the same line stage and power stage, so I discounted the gain of the integrated amp.
Does this help clarify things?
Again, thanks for the help.
Cheers,
John |
Al, you are right, I misread Hdm's first reply when he said "I'm with Kal above", I read "I am Kal from above". I thought maybe Kal had two monikers. My mistake, I apologize to Kr4 and Hdm. No, 2.5V does not overload the VAC at all. Darkmoebius, thank you for the compliment on my system and yes it does sound pretty good, even after the downsizing of '08. Thanks also for the VAC manual link, but I do have the VAC manual, I just misplaced the Walker manual. The specs in the VAC Avatar Super manual do not give the line and amp section gain levels like the Avatar SE did. FWIW, the VAC replaced a stock ARC REF 3 preamp and a highly modified BAT VK-75SE by Bob Backert of RHB Dezigns running fully balanced. My cartridge is the low output version of the ZYX UNIverse S-SB, same as listed in my system at AA. I have tried the built in MM phono stage of the VAC using a cheap SUT with the same ZYX cartridge. The sound was pretty good, but not in the same league as the Walker phono stage. I would not expect the inboard phono stage of a $6500 integrated amp to beat a $6650 outboard phono stage though. I know, to be fair I probably should have tried the VAC with a better SUT, but I was nervous about spending big $$$ on a SUT without hearing it in my system first. Thanks again for that calculator, I saved it in my favorites. Thanks for all of your help too Al, you bring a wealth of knowledge to these forums that is very refreshing. I think I'll try to give Lloyd a phone call tommorrow. I still think I'm best to: a)check the DC offset in the Walker (no coupling caps, Lloyd believes the best cap is no cap). If that doesn't help then... b)change the line stage tubes in the VAC. Hopefully that will solve my problem, if not, then I will probably proceed to looking at higher output cartridges. Happy Holidays, John |
Thanks Doug, I don't know if that makes much difference though. It does increase the output voltage from my phono preamp from 0.48V to 0.58V, but that's a relatively small increase compared to the 2.5V that my CDP outputs.
I have read about differences between the two industry standards (CBS and JVC???). I never really delved into it though because the difference seemed rather minor when you're considering the difference in a 0.24 mV output and a 1.25 mV output cartridge. If I do wind up looking for a new cartridge, I can't see considering one with less than a 1.0 mV output regardless of measuring standard.
Cheers,
John |
Thanks Thom. Darkmoebius posted a calaculator on his first response on this thread too, It's a little different from yours, but both have their strengths, thank you.
Happy Holidays to all,
John |
Thanks to all for all of your help. The problem is solved, though I'm not exactly sure what the problem was, since I made several changes, but my guess would be the problem was using unshielded interconnects.
First, I finally got in touch with Lloyd, and checked the DC offset in my Walker phono stage, it checked out fine. Then, I noticed that I had moved the turntable motor to adjust the belt drive higher on the platter, so I put the motor back into it's original position at the very bottom of the platter. Finally, I changed the 2 meter interconnects from my Walker Signature phono stage to my VAC integrated amp from unshielded XLO Signature 3 to shielded Von Gaylord Chinchilla, and Viola!! The noise floor is gone. Licorice Pizza sounds wonderful again, I'm spinning Jazz at the Pawnshop right now.
I've notice that the volume control knob is lower now, control knob at 11 o'clock. This I can't explain, except that maybe I was trying to turn the volume up louder to hear the music, but in doing so, it also raised the noise floor too.
Anyway, many thanks to all again for all of your help. A happy and healthy new year to all!
Cheers,
John |
