sreten has whipped together a pretty cool approach that fits the
existing driver sizes and will work together These models will work in an open baffle and not all will.
He knows a lot more than me also, so I'd go with this.
It is unfortunate that they aren't more efficient, but probably fine for normal listening levels.
I suspect that they will sound a LOT better.
existing driver sizes and will work together These models will work in an open baffle and not all will.
He knows a lot more than me also, so I'd go with this.
It is unfortunate that they aren't more efficient, but probably fine for normal listening levels.
I suspect that they will sound a LOT better.
Re: follow up
Both of the smaller VMs i have parted out had quite nice little drivers -- 5x7" FRs.
99.9999% (or so) of the drivers sold today are permanent magnet... what i think you mean is alnico magnets. Some of those alnico drivers contend with (and some tronce) many a modern speaker. I scronge a significant portion of my incme recycling alnico speakers.
These thou are not the best of the day -- the 3 or 4" thimble magnet tweeter tells the story (some of the 2" thimbles from japan OTOH are quite good). got a pic of the front of the speakers?
The 12" is made by Carbonneau ... that is the 719 code stamped on the basket (i've just collected and put up a page with many of these codes on an as unfinished web site
http://64.251.73.249/sites/FAL/EIA-SpeakerCodes.html
The XO is just a simple series cap on the tweeter... what is it's value (and the measured tweeter impedance?)?
:^) Busy, busy busy...
No way... what are the output tubes? And how many are there?
dave
Both of the smaller VMs i have parted out had quite nice little drivers -- 5x7" FRs.
giacomo said:
99.9999% (or so) of the drivers sold today are permanent magnet... what i think you mean is alnico magnets. Some of those alnico drivers contend with (and some tronce) many a modern speaker. I scronge a significant portion of my incme recycling alnico speakers.
These thou are not the best of the day -- the 3 or 4" thimble magnet tweeter tells the story (some of the 2" thimbles from japan OTOH are quite good). got a pic of the front of the speakers?
The 12" is made by Carbonneau ... that is the 719 code stamped on the basket (i've just collected and put up a page with many of these codes on an as unfinished web site
http://64.251.73.249/sites/FAL/EIA-SpeakerCodes.html
The XO is just a simple series cap on the tweeter... what is it's value (and the measured tweeter impedance?)?
Variac said:
:^) Busy, busy busy...
No way... what are the output tubes? And how many are there?
dave
I would agree with sreten's modernization approach* except for one caveat -- the existing speakers are likely at least 6 dB more efficient, so you may run into volume limitations. Like FlaCharlie the VM amps i've seen are SE EL84 or 6V6 -- good for maybe 4-4.5 W.
*(i've 2 projects in queue that take the same approach, one even has an 871 in it -- the other an unobtanum TB that you could consider to be a super 871)
dave
*(i've 2 projects in queue that take the same approach, one even has an 871 in it -- the other an unobtanum TB that you could consider to be a super 871)
dave
Any further input would help a great deal - as I said I'm no expert
on single driver type speakers - though I think they are the right
type of speaker for this application.
But for low power valve kit 6dB is a lot to lose.
Thinking about it further - there is no particular reason
to stay with a 12" and 3"/4" units. With a new baffle
you could fit any driver / driver combination you like.
Checking the LDSG index
http://ldsg.snippets.org/sect-3
The Adire Audio HE10.1 could be considered ? ( a bit over budget )
http://www.adireaudio.com/diy_audio/monitors/monitor_kits.htm
Higher efficiency options could be the
Fostex FE108 + another driver ? Fostex FE206E ?
http://www.madisound.com/
And this Pioneer B20FU20-51W ? seems a good budget choice :
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=290-045
Regarding the speakers acoustically :
I assume the back is a slotted hardboard piece popular at the time.
AFAIK with such a small baffle some acoustic resistance behind
the driver would help. So stuffing behind the baffle with rockwool
could help ? Also using something like heavy duty nylon carpet,
two layers? cut to fit the two side sections and bottom section
behind the baffle (held in place by the stuffing) to form lossy
baffle extensions could help.
sreten.
on single driver type speakers - though I think they are the right
type of speaker for this application.
But for low power valve kit 6dB is a lot to lose.
Thinking about it further - there is no particular reason
to stay with a 12" and 3"/4" units. With a new baffle
you could fit any driver / driver combination you like.
Checking the LDSG index
http://ldsg.snippets.org/sect-3
The Adire Audio HE10.1 could be considered ? ( a bit over budget )
http://www.adireaudio.com/diy_audio/monitors/monitor_kits.htm
Higher efficiency options could be the
Fostex FE108 + another driver ? Fostex FE206E ?
http://www.madisound.com/
And this Pioneer B20FU20-51W ? seems a good budget choice :
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=290-045
Regarding the speakers acoustically :
I assume the back is a slotted hardboard piece popular at the time.
AFAIK with such a small baffle some acoustic resistance behind
the driver would help. So stuffing behind the baffle with rockwool
could help ? Also using something like heavy duty nylon carpet,
two layers? cut to fit the two side sections and bottom section
behind the baffle (held in place by the stuffing) to form lossy
baffle extensions could help.
sreten.Hi again,
To answer FlaCharlie's question:
I've had these speakers going for about six months now and have been trying to pinpoint where some of my sound problems were coming from. One of my tweeters has a nice tear in it too, (found this out after removing everything from the cab) and the cone does feel to be rather brittle. My presumption is that this unit was sitting in an unfriendly basement for about thirty years.
Another problem I have is that one speaker keeps cutting out depending on the program material. Bass vibrations seem to be jiggling the thin wires (sorry, don't know the nomenclature) that connect the speaker to the basket.
A third problem is that I really believe that the woofers aren't handling the bass as well as they should be. That could be from the change in recording methods from when the unit was made (1959) to now. I don't know the bottom frequency for the woofers but I'd be surprised if they went below 80hz. When I hooked up my 20/20s to the amp (50hz bottom) the sound was a lot fuller (though again, these speakers are 4ohm so not a true test)
And on to Planet10's:
Yes, I must have got that wrong about the 140W. That's what's stamped on the back. There are 8 tubes, the audio outputs being #6AQ5. The capacitor is marked: 85 MFD. 2. - TOC V.D.C. 100. The tweeter is marked 3516H-VI-3514-20 and 18558-2 220917. See the pic, I've uploaded
And back to sreten's:
Yes, the back is vented and screws into the cabinet. But I'm unsure of what to do now about the 'slanted' mounting system. Aesthetically, I'd like to keep the unit together as I have in the picture, but the angle of those mounts puts the sweet spot at about 3 feet from the unit. Not really ideal for a living room. I suppose I could rip them out and realign but I did want to avoid surgery. Same goes for the mounting board. In theory I could go with any combination and get a new board made up. I'd be relying on a lumber yard to cut the holes out to exact measurement and I've found, by experience, that they rarely are as exacting as I'd like them to be.
Re: Loudness
Funny, but I think with the 20/20s hooked up I've lost a few dbs. I turned the amp up to 10 on them and they were no where nearly as loud as the original speakers were at that level. They did, however, offer more clarity than the originals.
Kind regards,
Giacomo
To answer FlaCharlie's question:
I've had these speakers going for about six months now and have been trying to pinpoint where some of my sound problems were coming from. One of my tweeters has a nice tear in it too, (found this out after removing everything from the cab) and the cone does feel to be rather brittle. My presumption is that this unit was sitting in an unfriendly basement for about thirty years.
Another problem I have is that one speaker keeps cutting out depending on the program material. Bass vibrations seem to be jiggling the thin wires (sorry, don't know the nomenclature) that connect the speaker to the basket.
A third problem is that I really believe that the woofers aren't handling the bass as well as they should be. That could be from the change in recording methods from when the unit was made (1959) to now. I don't know the bottom frequency for the woofers but I'd be surprised if they went below 80hz. When I hooked up my 20/20s to the amp (50hz bottom) the sound was a lot fuller (though again, these speakers are 4ohm so not a true test)
And on to Planet10's:
Yes, I must have got that wrong about the 140W. That's what's stamped on the back. There are 8 tubes, the audio outputs being #6AQ5. The capacitor is marked: 85 MFD. 2. - TOC V.D.C. 100. The tweeter is marked 3516H-VI-3514-20 and 18558-2 220917. See the pic, I've uploaded
And back to sreten's:
Yes, the back is vented and screws into the cabinet. But I'm unsure of what to do now about the 'slanted' mounting system. Aesthetically, I'd like to keep the unit together as I have in the picture, but the angle of those mounts puts the sweet spot at about 3 feet from the unit. Not really ideal for a living room. I suppose I could rip them out and realign but I did want to avoid surgery. Same goes for the mounting board. In theory I could go with any combination and get a new board made up. I'd be relying on a lumber yard to cut the holes out to exact measurement and I've found, by experience, that they rarely are as exacting as I'd like them to be.
Re: Loudness
Funny, but I think with the 20/20s hooked up I've lost a few dbs. I turned the amp up to 10 on them and they were no where nearly as loud as the original speakers were at that level. They did, however, offer more clarity than the originals.
Kind regards,
Giacomo
Attachments
As I said the 140W stamped on the back is
a rating for power drawn from the supply.
Single ended output tubes won't like low impedance loading.
Regarding the baffle I wouldn't change the angle.
Regarding your bass extension possibly the stuffing
and lossy wall lining would extract a little more bass.
Certainly with low power and an open baffle a high Q bass unit
should give some bass back without needing extra power.
Regarding the baffle you could a use a subboard for driver
mounting that screws on to the front of the original baffle
covering up the holes but being somewhat smaller than
the baffle proper.
I am concerned about efficiency with my original suggestion.
If the 20/20's (?) were not loud enough then these probably
won't be either.
I'll see if I can find a more efficient pairing.
sreten.
a rating for power drawn from the supply.
Single ended output tubes won't like low impedance loading.
Regarding the baffle I wouldn't change the angle.
Regarding your bass extension possibly the stuffing
and lossy wall lining would extract a little more bass.
Certainly with low power and an open baffle a high Q bass unit
should give some bass back without needing extra power.
Regarding the baffle you could a use a subboard for driver
mounting that screws on to the front of the original baffle
covering up the holes but being somewhat smaller than
the baffle proper.
I am concerned about efficiency with my original suggestion.
If the 20/20's (?) were not loud enough then these probably
won't be either.
I'll see if I can find a more efficient pairing.
sreten.
Plan B
Plan B
*****
Well after some investigation - how about the Fostex FE107E
4" unit from Madisound. According to specs this hits a genuine
90dB/W across the midrange which is a good 4dB more than
the TB.
http://madisound.com/fe107e.pdf
Though the downside is bass hits 80dB rather rapidly.
Further investigation hasn't turned up a better bass unit,
only that its being sold for rather more elsewhere :
http://www.simplyspeakers.com/14replacements.htm
Using the Goldwood 12" with the Fostex will compensate less
for the baffle rolloff but should still work reasonably well to
extend bass and bass power handing.
I think the 280Hz series crossover as described before should be OK.
My other suggestion with the Fostex is a miniature neodynium dome tweeter :
http://www.speakercity.com/clearance/clearance_drivers.shtml
2nd driver down : rolled in 1st order at about 7K should give
more even treble dispersion. It shouldn't be difficult to place
near the join or in between the two drivers.
Unfortunately impedance is not given. A guess is 6R and this
gives a capacitor needed of ~ 4uF.
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=027-421
The tweeter + series capacitor is wired in parallel with the Fostex.
Any thoughts on Plan B ?
sreten.
Plan B
*****
Well after some investigation - how about the Fostex FE107E
4" unit from Madisound. According to specs this hits a genuine
90dB/W across the midrange which is a good 4dB more than
the TB.
http://madisound.com/fe107e.pdf
Though the downside is bass hits 80dB rather rapidly.
Further investigation hasn't turned up a better bass unit,
only that its being sold for rather more elsewhere :
http://www.simplyspeakers.com/14replacements.htm
Using the Goldwood 12" with the Fostex will compensate less
for the baffle rolloff but should still work reasonably well to
extend bass and bass power handing.
I think the 280Hz series crossover as described before should be OK.
My other suggestion with the Fostex is a miniature neodynium dome tweeter :
http://www.speakercity.com/clearance/clearance_drivers.shtml
2nd driver down : rolled in 1st order at about 7K should give
more even treble dispersion. It shouldn't be difficult to place
near the join or in between the two drivers.
Unfortunately impedance is not given. A guess is 6R and this
gives a capacitor needed of ~ 4uF.
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=027-421
The tweeter + series capacitor is wired in parallel with the Fostex.
Any thoughts on Plan B ?
sreten.
6AQ5s ... 2 or 4 of them? 1 output transformer or 2? Frank is probably right... thinking back, both the VMs i disassembled were PP mono, so you may well have a PP 6AQ5 which would be 10-15W.
In 1959 is was quite common to see mono units with 2 speakers... confirming the number of output transformers would sort that question.
Or a scan of the schematic
dave
Note: the pioneer B20 really needs a tweeter with it, and isn't as efficient as speced.
In 1959 is was quite common to see mono units with 2 speakers... confirming the number of output transformers would sort that question.
Or a scan of the schematic
dave
Note: the pioneer B20 really needs a tweeter with it, and isn't as efficient as speced.
re: schematics
Tried to scan but due to upload limits, makes it indecipherable.
The unit is definitely stereo and has a mono/stereo selector switch. There are a total of 8 tubes.
4 are 6AQ5, Audio Output
2 are 12AX7/ECC83, AF Amp -
1 is 12AX7/ECC83, Phase Inv.
1 is 6CA4/EZ81, Rectifier
I'm posting another section that may be helpful. Unfortunately, there is no helpful info in the booklet on the speakers. It just lists the VM part # and size.
As for the transformer section it only lists the vm part # for those too but there is an entry for both right and left channels and looking at the pic supplied there are definitely two in there.
I'll try again with the schematics and see if I can get a decipherable copy uploaded.
Thanks again,
Giacomo
Tried to scan but due to upload limits, makes it indecipherable.
The unit is definitely stereo and has a mono/stereo selector switch. There are a total of 8 tubes.
4 are 6AQ5, Audio Output
2 are 12AX7/ECC83, AF Amp -
1 is 12AX7/ECC83, Phase Inv.
1 is 6CA4/EZ81, Rectifier
I'm posting another section that may be helpful. Unfortunately, there is no helpful info in the booklet on the speakers. It just lists the VM part # and size.
As for the transformer section it only lists the vm part # for those too but there is an entry for both right and left channels and looking at the pic supplied there are definitely two in there.
I'll try again with the schematics and see if I can get a decipherable copy uploaded.
Thanks again,
Giacomo
Attachments
Actually the 6AQ5 tube is the electrical equivalent of the 6V6 but is smaller in size. It should put out about 10-12 watts per channel PP. As far as the speakers go why not just set a pair of small to medium sized bookshelf speakers inside the original enclosures. This would preserve the original styling yet you would have more options and fewer limitations.
Adding A Curve Ball Here Hi,
RE: New speakers in box
Yes, that's what I did with the Event 20/20s. They're slipped inside the cabs now, but I just thought that I could replace the drivers and get a better quality for the same amount of money, or even less, than what I would pay for for boxed speakers.
One other comment I have to make, though, is that since much of my record collection consists of 60s soul and ska I'd like to have a pair of woofers that will have a good bottom. As I wrote in a previous post, I lost a lot of bass on the original speakers and the 20/20s made a big difference.
Again, thanks for everyone's help and input here. Speaker design is obviously not my bailiwick so I'll be holding off purchase till you experts let me know what I need. But I think I got a good handle on the basics now.
Kind regards,
Giacomo
RE: New speakers in box
Yes, that's what I did with the Event 20/20s. They're slipped inside the cabs now, but I just thought that I could replace the drivers and get a better quality for the same amount of money, or even less, than what I would pay for for boxed speakers.
One other comment I have to make, though, is that since much of my record collection consists of 60s soul and ska I'd like to have a pair of woofers that will have a good bottom. As I wrote in a previous post, I lost a lot of bass on the original speakers and the 20/20s made a big difference.
Again, thanks for everyone's help and input here. Speaker design is obviously not my bailiwick so I'll be holding off purchase till you experts let me know what I need. But I think I got a good handle on the basics now.
Kind regards,
Giacomo
Hi Giacomo,
simply put with only 10W to play with the very nature of the
open baffle design means you are not going to get good low
bass at a decent play back level.
You cannot maintain the open baffle sound and have
good bass at the same time with 10W per channel.
A highish efficiency overdamped reflex box is needed / ideal.
This would need your boxes to be reworked.
The cloth looks easy to remove / replace.
The sides of the boxes would need a layer of plywood (1/4")
glued to them on the inside. On the outside of the sides the
spaces would be filled with dry sand* and a thin layer of
aluminium sheeting glued on to hold the sand in place.
(*using plaster is another option, easy to sand flat)
The bottom of the box needs to be sealed and a new back is
needed - suggest 5/8" plywood for this.
The front of the box the frame would be cutout and the edges
bevelled. A new front baffle 3/4" plywood would screw to the
back of this.
A front to back T brace would be used.
The cloth should be easy to refit.
The drivers and crossover you would now use are
different, as it would no longer be an open baffle.
The only way for good bass though, are you prepared to do this work ?
sreten.
simply put with only 10W to play with the very nature of the
open baffle design means you are not going to get good low
bass at a decent play back level.
You cannot maintain the open baffle sound and have
good bass at the same time with 10W per channel.
A highish efficiency overdamped reflex box is needed / ideal.
This would need your boxes to be reworked.
The cloth looks easy to remove / replace.
The sides of the boxes would need a layer of plywood (1/4")
glued to them on the inside. On the outside of the sides the
spaces would be filled with dry sand* and a thin layer of
aluminium sheeting glued on to hold the sand in place.
(*using plaster is another option, easy to sand flat)
The bottom of the box needs to be sealed and a new back is
needed - suggest 5/8" plywood for this.
The front of the box the frame would be cutout and the edges
bevelled. A new front baffle 3/4" plywood would screw to the
back of this.
A front to back T brace would be used.
The cloth should be easy to refit.
The drivers and crossover you would now use are
different, as it would no longer be an open baffle.
The only way for good bass though, are you prepared to do this work ?
sreten.
Perhaps he can have a separate sub with amp and keep the open baffles but with new drivers. the baffles woul have to be as big as can be fit in t he cabinets and
iT appears that the open baffles still might not go low enough to cross over to a sub at a frequency that can't be localized. He would then need 2 sub- one at each speaker which I'm sure he doesn't want!!
iT appears that the open baffles still might not go low enough to cross over to a sub at a frequency that can't be localized. He would then need 2 sub- one at each speaker which I'm sure he doesn't want!!
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