Ahh.....Nikola,
You think the Germans have better quality control :~}
You may be right?
How about the Americans?
You think the Germans have better quality control :~}
You may be right?
How about the Americans?
Feedback blew my phono stage?
Ok....I don't know what's going on here but here's my set-up
HALCRO
On the right hand side is my 'nude' Victor TT-101 DD turntable supported on spikes surrounded by 3 three tonearms on separate solid bronze armpods.
The 3 arms are connected separately to the Halcro DM10 preamp's phonostage via 2.5 metre long balanced Cardas Golden Ref phono cables.
With MM cartridges (I have around 30).....there are no problems.
With LOMC cartridges however......if I rest the stylus on the record without the motor turned on......I can induce a low frequency feedback through the speakers if I turn up the volume sufficiently?
Nothing I did to support the turntable differently.....could eliminate this problem so I have simply been playing MM cartridges through this turntable.
Recently.....I mounted an Acutex 420STR MM cartridge on the SAEC tonearm and discovered that it produced the same feedback symptoms as the LOMCs?
In experimenting with differing support methods for the Victor.....I forgot to turn the volume down before hitting the 'mute' button to 'OFF'....and an almighty noise knocked out my phono stage and tripped the protection on the left channel Halcro monoblock.
The 'Balanced' XLR inputs for the phonostage now produce no output whilst the RCA inputs produce a feeble output in the right channel only.
Any Gurus here with some ideas for the cause of this problem would be much appreciated?
Incidentally......no such problems with the 3 tonearms on the Raven AC connected to the same preamp inputs....even with LOMCs?
HALCRO
On the right hand side is my 'nude' Victor TT-101 DD turntable supported on spikes surrounded by 3 three tonearms on separate solid bronze armpods.
The 3 arms are connected separately to the Halcro DM10 preamp's phonostage via 2.5 metre long balanced Cardas Golden Ref phono cables.
With MM cartridges (I have around 30).....there are no problems.
With LOMC cartridges however......if I rest the stylus on the record without the motor turned on......I can induce a low frequency feedback through the speakers if I turn up the volume sufficiently?
Nothing I did to support the turntable differently.....could eliminate this problem so I have simply been playing MM cartridges through this turntable.
Recently.....I mounted an Acutex 420STR MM cartridge on the SAEC tonearm and discovered that it produced the same feedback symptoms as the LOMCs?
In experimenting with differing support methods for the Victor.....I forgot to turn the volume down before hitting the 'mute' button to 'OFF'....and an almighty noise knocked out my phono stage and tripped the protection on the left channel Halcro monoblock.
The 'Balanced' XLR inputs for the phonostage now produce no output whilst the RCA inputs produce a feeble output in the right channel only.
Any Gurus here with some ideas for the cause of this problem would be much appreciated?
Incidentally......no such problems with the 3 tonearms on the Raven AC connected to the same preamp inputs....even with LOMCs?
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- 38 posts total
Well, dear Henry, Americans lost the control of their domestic and foreign debts, their jobs, Irak and Avganistan,etc., while we all in the European Union hope that the Germans will liberate us from the Euro crisis. They are really in control and I am not sure who actually lost the II WW. The Britons who hope to earn some money with tourism ( their industrial capability you can see by the Linn LP-12) teach their kids : don't mention the war to any German tourist. Regards, |
It doesn't look that way from where I sit. National debt(s) and lack of jobs are problems everywhere in the so-called industrialized world these days, are they not? In southern Europe the problem is far worse than anywhere in the US. On topic, I agree with Dover, if Mr. Halcro in Adelaide will not at least give you a schematic, I would consider dumping the DM10 at this juncture. But you also own the amplifiers, as I recall. |
Today the Halcro designer writes:-I too can't imagine how the choke failures could have been caused by the turntable. The only semblance of an explanation I can think of is that the abrupt eruption of the very high level oscillation, caused by feedback, may have in turn caused a very large voltage transient to be generated across the chokes as a result of inductive kick (chokes are inductors). And perhaps that high voltage transient somehow coupled into whatever circuit the electrolytic capacitor is located in (perhaps it serves as a filter for some internal DC supply voltage), causing or hastening its demise. FYI, see page 6 of this document for an explanation of what a common mode choke is. Best regards, -- Al |
Hi Al, I mentioned to 'Mr Halcro' that I had the 'ground' cable of my Victor TT, attached to one of the DM58 monoblock amps and could THAT cause the problem? It is possible that the grounding on the power amp may cause a voltage difference that could burn out the chokes. I would also be interested to hear if the feedback problem went away as well.Is his reply. What do you think? Regards Henry |
- 38 posts total