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 Post subject: Difference between HMV 101 and 102 'arm'
PostPosted: Sun Mar 04, 2018 8:16 am 
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Victor I
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I noticed that at the end of the 'arm', where the sound box is inserted, the HMV 101 seems to have a metal insert where-as the HMV 102 does not have one

I just wondered why this would be.

Thank you very much for any information about this.


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 Post subject: Re: Difference between HMV 101 and 102 'arm'
PostPosted: Mon Mar 05, 2018 11:29 am 
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Victor IV
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I guess the internal metal piece in the 101 tonearm is designed to butt close to the opening in the back of the soundbox producing a continuous conduit ? Can't think of any other reason :? The 102 soundbox has a conical plug which presumably is designed to increase the air pressure behind the soundbox , perhaps doing this it then doesn't need a continuous conduit ? out of my depth here though


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 Post subject: Re: Difference between HMV 101 and 102 'arm'
PostPosted: Mon Mar 05, 2018 12:56 pm 
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Victor III
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Evidently all this is just matching the bore/design of the tonearm (which of course is the start of the horn system; on both models carefully designed but quite different) with the aperture of each soundbox where they connect. The "phase plug" in the 102 soundboxes is a mysterious thing but was clearly thought to have some beneficial effect on the sound.


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 Post subject: Re: Difference between HMV 101 and 102 'arm'
PostPosted: Mon Mar 05, 2018 7:12 pm 
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Victor IV
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In addition to reducing the size of the tonearm's throat, it looks like it certainly would add some weight to the end of the tonearm where it mates with the sound box, possibly forcing the #4 sound box to remain in a more balanced position--perpendicular to the record's surface. (Along this line, I'm wondering what the weight of the #4 sound box is compared to that of the Exhibition and #2.)

The Victor tonearms used on those models equipped with the #4 sound box--the VV-1-4, VV-1-5, VV-1-6, VV-2-30, VV-1-70, etc.--so far as I know, were not fitted with the inside tube. I know for a fact that the VV-1-5 had a conventional throat.

OrthoFan


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 Post subject: Re: Difference between HMV 101 and 102 'arm'
PostPosted: Tue Mar 06, 2018 9:18 am 
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Victor I
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soundgen wrote:
I guess the internal metal piece in the 101 tonearm is designed to butt close to the opening in the back of the soundbox producing a continuous conduit ? Can't think of any other reason :? The 102 soundbox has a conical plug which presumably is designed to increase the air pressure behind the soundbox , perhaps doing this it then doesn't need a continuous conduit ? out of my depth here though



Oh yes, I see what you mean. Different designs of the N0 4 and No 16 sound boxes required different 'arm designs.

Thank you


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 Post subject: Re: Difference between HMV 101 and 102 'arm'
PostPosted: Tue Mar 06, 2018 9:22 am 
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Victor I
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Orchorsol wrote:
Evidently all this is just matching the bore/design of the tonearm (which of course is the start of the horn system; on both models carefully designed but quite different) with the aperture of each soundbox where they connect. The "phase plug" in the 102 soundboxes is a mysterious thing but was clearly thought to have some beneficial effect on the sound.


I see - could you please clarify to me what you mean by 'phase plug' - which part of the hmv 102 is this please ?


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 Post subject: Re: Difference between HMV 101 and 102 'arm'
PostPosted: Tue Mar 06, 2018 9:31 am 
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Victor I
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OrthoFan wrote:
In addition to reducing the size of the tonearm's throat, it looks like it certainly would add some weight to the end of the tonearm where it mates with the sound box, possibly forcing the #4 sound box to remain in a more balanced position--perpendicular to the record's surface. (Along this line, I'm wondering what the weight of the #4 sound box is compared to that of the Exhibition and #2.)

The Victor tonearms used on those models equipped with the #4 sound box--the VV-1-4, VV-1-5, VV-1-6, VV-2-30, VV-1-70, etc.--so far as I know, were not fitted with the inside tube. I know for a fact that the VV-1-5 had a conventional throat.

OrthoFan


Most interesting. So some Victors didn't have the insert then. I have just weighed the No 4 sound box and it is just over 5 ounces.

I haven't seen any other 101's and assume they have the insert as standard but this is worth checking when I find another one to look at.

Thank you very much.


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