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#1
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Loudness and Volume
Just read an article in Just Jukin about adding loudness control to
volume control circuit. I'm not quite sure exactly what the difference is here. Is this meant to keep the same sound level on all records played? I do notice on my RO1454 some records are much louder than others, so maybe this is what it is for. If so, can this type of circuit be added to my box? Thanks, Mike |
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#2
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Loudness and Volume
I don't have an answer for you but, what is "Just Jukin"?
Glen "NJ Mike" wrote in message ... Just read an article in Just Jukin about adding loudness control to volume control circuit. I'm not quite sure exactly what the difference is here. Is this meant to keep the same sound level on all records played? I do notice on my RO1454 some records are much louder than others, so maybe this is what it is for. If so, can this type of circuit be added to my box? Thanks, Mike |
#3
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Loudness and Volume
opps...Always Jukin..my mistake
Mike |
#4
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Loudness and Volume
Mike, what you are looking for is an "AVC" -or automatic volume
control. I'am not sure when Rock-ola started incorporating them, but I've owned a 1458 and 1465 both of those models had AVC. It's not really practical to try to build it into your existing amp but since the pickup is the same and the other connections -might- also be, you could look into getting a slightly later amp that has avc. Rock-Ola didn't often make major changes internally so with a little know-how almost any mono (R-O)amp could be accommodated. BTW: A "loudness" control if just a method where lower setting of the volume control boosts the bass (and sometime the highest treble slightly) to compensate for human ear's deficiencies at low volume levels. It does not equalize the levels of the records. You R-O already has such a control. Rob+ On Feb 17, 9:33*am, NJ Mike wrote: Just read an article in Just Jukin about adding loudness control to volume control circuit. I'm not quite sure exactly what the difference is here. *Is this meant to keep the same sound level on all records played? I do notice on my RO1454 some records are much louder than others, so maybe this is what it is for. *If so, can this type of circuit be added to my box? Thanks, Mike |
#5
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Loudness and Volume
Thanks for the info rob. I'll have to check into what amp might be
swapable with the one I have. Also, how effective is the AVC on the Rockolas? I haven't had a lot of exposure to the different models when playing. Mike |
#6
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Loudness and Volume
Mike, there are a couple of points regarding changing amps here; the
most important is that your machine uses a field coil speaker (I believe) this is an electric coil instead of magnet at the rear of the speaker. If you change to a later amp, you'll also have to change the speaker as again I believe, the 1454 was the last year to use a field coil. As for AVC efficacy, ALL these circuits are subtractive in nature. That is, they reduce the level (gain) as the level from the pickup increases. So, a loud record with get attenuated and a low one will get little/no attenuation. The original ceramic pickup was fairly high output, it also was not designed for dealing with stereo records. If you change over to a more modern pickup, it is possible that it's output will be somewhat lower and thus the AVC's ability to equalize all records will be less effective. In my own experience with the 1458 and 1465 I replaced the original pickup (same as yours) with a Pickering magnetic and used an outboard pre-amp. I tested the amount of gain reduction on the AVC and found that a loud record was compressed by about 16 decibels and thus a low record was brought up to approx the same level. The sort of modification that you envision requires a degree of electronics knowledge, but it is not that difficult. In the case of a 1454 it might be better to consider selling the machine and getting a slightly later one. A simple compromise might be to use a remote volume control (RVC) that allows you to adjust the level without have to get to the back of the machine. These are available used and fairly easy to set up, in fact you could probably just lengthen the wire on your existing volume control and mount it in a box. Rob. On Feb 18, 8:03*am, NJ Mike wrote: Thanks for the info rob. I'll have to check into what amp might be swapable with the one I have. Also, how effective is the AVC on the Rockolas? *I haven't had a lot of exposure to the different models when playing. Mike |
#7
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Loudness and Volume
Thanks for reminding me to play my 1454! I just played 6 tunes on it,
love that machine! It doesn't *sound* like I have a VLC on my 1454 either. Funny, because it does sound like my Tempo II has one, for sure. It's actually kind of distracting, the record starts off loud, then the VLC kicks in and softens the volume. Guess it was something Rockola added later. The 1434 sounds like it's not a feature on that machine either. Keep Jukin'! Brad, Vacaville, CA http://www.jukeboxnut.com On Feb 17, 6:33*am, NJ Mike wrote: Just read an article in Just Jukin about adding loudness control to volume control circuit. I'm not quite sure exactly what the difference is here. *Is this meant to keep the same sound level on all records played? I do notice on my RO1454 some records are much louder than others, so maybe this is what it is for. *If so, can this type of circuit be added to my box? Thanks, Mike |
#8
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Loudness and Volume
On Feb 19, 12:30*pm, jukeboxnut wrote:
Thanks for reminding me to play my 1454! I just played 6 tunes on it, love that machine! It doesn't *sound* like I have a VLC on my 1454 either. Funny, because it does sound like my Tempo II has one, for sure. It's actually kind of distracting, the record starts off loud, then the VLC kicks in and softens the volume. Guess it was something Rockola added later. The 1434 sounds like it's not a feature on that machine either. Keep Jukin'! Brad, Vacaville, CAhttp://www.jukeboxnut.com Mike, I looked at a schematic for your Tempo's amp and it looks like R- O went to the use of thermistors for AVC. The problem with this circuit is that is makes no provision for "squelch" which sets the volume (gain) very low at the start of a record and releases the circuit so that record level then sets the gain. The thermistor circuit has no such provision. Rock ola used a very effective tube based AVC for, it seems, only two models (1458-1465) those had an AVC squelch which worked just as the AVC's in Seeburg- Wurlitzer-AMI. I can only guess that R-O was seeking to make the maps simpler/cheaper by using thermistors. I've owned a 1496, a Grand Prix and 432. The 1496 and 432 were tube and used the thermistors, the trick was to set the input gain pots so that a really "loud" record would not overshoot (blast) too much at the beginning. The problem is that it reduces the circuit's ability to even out the differences between loud and low because the system then may not always have enough gain to bring up a low record, but it is a good compromise. I experimented back in 1987 with making a squelch circuit for the thermistor design. It added a set of contacts to the mute relay that put a small amount of AC from the tube heater circuit into the thermistors to bias them down, just as a loud record would do. When the machines un-muted the AC was eliminated and volume slowly came up. I don't know why R-O didn't go this route, but I guess the goal of simpler/cheaper trumped. Rob On Feb 17, 6:33*am, NJ Mike wrote: Just read an article in Just Jukin about adding loudness control to volume control circuit. I'm not quite sure exactly what the difference is here. *Is this meant to keep the same sound level on all records played? I do notice on my RO1454 some records are much louder than others, so maybe this is what it is for. *If so, can this type of circuit be added to my box? Thanks, Mike |
#9
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Loudness and Volume
Rob,
Thanks for your detailed answers and explanations. I'm primarily and EM pinball guy, so much of the detail is a bit beyond my knowledge level, but I'm trying. The box I have is a 1454, and I'm wondering if it might be a whole lot simpler to get a remote volume control. Do you know if RO made one for this era, and if not, would it be as simple a wiring a additional volume pot in series with the one already connected? Thanks again, Mike in NJ |
#10
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Loudness and Volume
Mike, I agree that an RVC is the best (and most original) way to go
here. Go he http://www.verntisdale.com/Rockolaschem.htm Then lookup your model: http://www.verntisdale.com/schem/1454.jpg _you'll see that the model of RVC for your amp is #1927-A Which is a mono unit and looks similar to this: http://www.collectibles-articles.com...560538233.html I don't know if that particular one would work, but the plug looks correct. Good news is that ANY 25K/Ohm pot with a dual taps can be used here..Seeburg pots are fine. I recall that the guy who hosts the schematics was selling reproductions pots for something like $25. The is the pot only w/out a box, cord or plug. You could also try Orange trading for an original and go to Always Jukin magazine http://alwaysjukin.storesecured.com/...ssues/list.htm D-L the free copy and peruse the AD's for other sources. Get back to me w/any Q's Rob On Feb 21, 1:40*pm, NJ Mike wrote: Rob, Thanks for your detailed answers and explanations. *I'm primarily and EM pinball guy, so much of the detail is a bit beyond my knowledge level, but I'm trying. The *box I have is a 1454, and I'm wondering if it might be a whole lot simpler to get a remote volume control. *Do you know if RO made one for this era, and if not, would it be as simple a wiring a additional volume pot in series with the one already connected? Thanks again, Mike in NJ |
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