Dan
There is one more possibility and its so obvious I am sure you have already done it but.....
Maybe it was just one or a couple of particular albums?
You have played the same albums that you noted the feedback on?
If not this then it must have been the phase of the moon or a solar eclipse or them pesky Gremlins again!
Happy New Year!
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For what it's worth, yes, my Lenco is in a slate plinth. It is further modified in many other ways. You could say it is a custom turntable that uses the Lenco motor, idler arm and wheel, and platter, and even the platter was treated so as to deaden any tendency to ring. If you need further details, just ask. Happy New Year to all.
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Hello to the good folks that have posted to my tonearm/cartridge thread. I am now on a mystery quest, as I haven't been able to repeat the conditions that caused the feedback to occur. I have tried with the subwoofer on and off with both my tube amps, no feedback. The only thing left is to try using my Class D Audio amp. It's rarely used when I play vinyl, so that must be the culprit.
Anyway, thanks to you all for your help, regards, and Happy New Year,
Dan
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Chris, I wish that would be the case, but there is no room anywhere near my listening chair for a sub. I do wonder, though, about the close placement between my 15" Tannoy sub right next to my 845 amp. Well, time to do some more listening.
Thanks,
Dan
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Sounds amp related Dan. Easy to check out.
Also as your sub is crossed at 60 hz you have an opportunity to use it in near field, placed beside your listening chair. This results in the Sub db level being used at probably 1/4 of the level it is at now. This results in better bass and a much less stressed out sub. My subs in the Quad room are placed on either side of the listening couch. |
Hi Chris, et al,
The sub is rolled off at 60HZ. When I finally got to listening, I tried first with the sub off. There was no feedback issue, using my SET 300B amp. I then turned the sub on, and there was no feedback at all.
I don't remember which of my three amps I was using when the feedback occurred. It may be the 845 amp, but I would have to swap out amps to be sure. So the problem must be amp-dependent. I will do further testing and get back to you.
Thanks, and Happy New Year,
Dan
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Happy New Year Guys. Dan The signal has a "fluttery" sound, or like a vibrato. Is this sound heard through your sub and your main speakers ? What HZ does your sub kick in at ? What happens if you turn off the sub ? Cheers Chris |
Uberwaltz, I have not changed phono stages, just the line stage. In any case, the MM gain is 50db, and MC gain is 66db.The gain provided by the line stage is 15db.
I've been using the same Modwright SWP 9.0 SE Phono Stage for around six or seven years now, this seems to be a new issue I don't remember encountering before. I remounted the Acutex again today, I'll try and sleuth out the problem some more. I'll get back to 'ya.
Thanks, and Happy New Year,
Dan
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Dan
A lot more gain could certainly contribute.
Do you know what gain?
I run 44db gain most of the time on my Nova 3 although not had the acutex mounted for a while and not with the Nova. Last time I used it was with a Chinook at 40db gain.
The 320str has over 3mv output so really should not need any more than 40db gain IMHO.
Is it possible to reduce the gain at the Phonostage?
Yes you would then need more preamp volume to bring you back to the volume level you decide but if it is Phonostage gain related you may have your answer. |
Uberwaltz, Lewm,
The feedback is volume dependent. It happens when I turn up the gain to where it's how I like to hear it, below the clipping point on some of my lower powered amps. And, as I mentioned, it sounds spectacularly good until the feedback begins. The signal has a "fluttery" sound, or like a vibrato.
Lew, I looked at your Lenco, is that a slate plinth it's in? Thinking about this, I've had this cartridge for years, and I don't remember having this issue before. The only thing that's different is a change in line stages, I went from a kit built Transcendent Sounds Grounded Grid to a Modwright SWL 9.0 Line Stage, which is much more musical, but I don't know how that would cause this feedback issue, although it does seem to have quite a bit more gain.
I hope get a handle on this, the M320 III STR is my favorite cartridge now, I kind of miss its use.
Regards,
Dan |
I love the Acutex 320STR III, and I have used it on my Dynavector DV505 and (believe it or not) on my Fidelity Research FR64S, where it really should not work because of the high compliance/high effective mass mismatch. I did use a lightweight (8 gram) headshell on the FR. The DV505 and 501 would have very low effective mass in the vertical plane and high effective mass in the horizontal plane. That is the deliberate intent of the design. There is no reason your Acutex should not work well on the DV501. I would suggest you look elsewhere to solve your problem, but buying a new tonearm is always an adventure, if that’s what you’re after.
Sorry, I did not see the above post where you say you would prefer not to replace the DV501. I agree. Can you say in more detail what you hear that you call "feedback"?
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Dan
You may find the MyMat helps, not sure as never had a feedback issue.
I assume at just 1mm thick you will be placing this on top of the copper plate.
Curious as to the statement " sounds spectacular until feedback sets in"
Is it at a certain frequency or pitch that it starts or purely volume level dependant? |
Raul, Uberwaltz, thanks for your replies. I'm not looking to replace my tonearm. I really enjoy having the Dynavector 501, and also, it's not feasible to mount another tonearm, as there's not enough acreage on my plinth.
So yes, I'm looking for a way to use my current arm with the M320 III STR. I have found it to be a phenomenal cartridge. What characteristics in a tonearm would be ideal, and if there is a mismatch, is there a way around it?
Ubertwaltz, by the way, I have ordered Slaw's My Mat. Maybe that might help, as I use only a TTW copper plate without a mat. The Acutex is the only cartridge I've had a feedback problem with.
Thanks and regards,
Dan
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Dan
I do not have the 320 str but do have the 312 str.
I have used this very successfully on my Garrard 401 with a Micro Seiki ma505ls arm with zero issues.
I have two 10" subs probably both approx 9 ft from the TT.
I know there are some very nice examples of the ma505 for sale but unsure if you are looking for new tonearm suggestions or finding a cure for present setup. |
