Hi, I'm a complete novice at speaker building, OB or otherwise, but I think that I would like to give it a try. The speakers would be used in a small room around 10 x 12 but with a vaulted ceiling. I am also experimenting with some absorbent room treatment panels. My amp is a 2 watt Decware SE84.
Based on info I read in some of the audio blogs I bought a pair of Wild Burro Betsy drivers that I installed in simple plywood baffles. These speakers really sound great with my amp. They have a large sound stage and image fairly well. What they lack is bass. I would like to add drivers to help with this that would be driven by a separate subwoofer plate amp. I am thinking about using Hawthorn Augies. If there are better choices in the Augies price range please let me know. Where I need help is what would be the best way to implement them. Should they be built into the same baffle as the Betsy's or should they have their own baffle? I would prefer to use the same baffle because of room size but I want to avoid any interference that they may cause to the Betsy's. I don't want to use a crossover on the Betsy's because my amp is only putting out 2 watts.
Any help on how I should go about adding some more bass to my system would be greatly appreciated.
Thanks
Based on info I read in some of the audio blogs I bought a pair of Wild Burro Betsy drivers that I installed in simple plywood baffles. These speakers really sound great with my amp. They have a large sound stage and image fairly well. What they lack is bass. I would like to add drivers to help with this that would be driven by a separate subwoofer plate amp. I am thinking about using Hawthorn Augies. If there are better choices in the Augies price range please let me know. Where I need help is what would be the best way to implement them. Should they be built into the same baffle as the Betsy's or should they have their own baffle? I would prefer to use the same baffle because of room size but I want to avoid any interference that they may cause to the Betsy's. I don't want to use a crossover on the Betsy's because my amp is only putting out 2 watts.
Any help on how I should go about adding some more bass to my system would be greatly appreciated.
Thanks
Hi,
There should be no problem using a common baffle.
With only 2 watts available you should at least
passive line level high pass drive to the Betsy's,
typically done by reducing the input capacitor.
rgds, sreten.
http://www.quarter-wave.com/OBs/OB_Design.pdf
There should be no problem using a common baffle.
With only 2 watts available you should at least
passive line level high pass drive to the Betsy's,
typically done by reducing the input capacitor.
rgds, sreten.
http://www.quarter-wave.com/OBs/OB_Design.pdf
OB with Sub
Hi there r: Agree with your approach to biamp using a subwoofer. Suggest you google-up Elliott Sound Products, go to projects page and scroll down to biamp and the subwoofer projects. Rod Elliott covers the basics there. ...regards, MichaelHi, I'm a complete novice at speaker building, OB... My amp is a 2 watt Decware SE84. What they lack is bass. ...I would like to add drivers to help with this that would be driven by a separate subwoofer plate amp. ...I don't want to use a crossover on the Betsy's because my amp is only putting out 2 watts.
Any help on how I should go about adding some more bass to my system would be greatly appreciated.
Thanks
Thanks for your reply's. The info on Elliot Sound Products looked interesting but I was planning on buying a factory made plate amp that already has crossover, phase, and volume controls built in.
The design article from quarter-wave also looked very interesting but I'm not sure how to incorporate the info into my project using the Betsy's that I already own. The Betsy's are hi efficiency full range drivers, so for now I have them connected directly to the output of the amp. I'm not using any caps or inductors. I have plenty of volume with nice dynamics, they just lack bass. I was hoping to add a sub that would just fill in some of the missing bass. At first I was going to just buy an Inclosed power subwoofer, but after reading about the Augie's I thought staying with an OB design for the sub also might be the way to go.
If I but both speakers in the same baffle, will I need to add a cap and inductor to the Betsy?
Thanks,
The design article from quarter-wave also looked very interesting but I'm not sure how to incorporate the info into my project using the Betsy's that I already own. The Betsy's are hi efficiency full range drivers, so for now I have them connected directly to the output of the amp. I'm not using any caps or inductors. I have plenty of volume with nice dynamics, they just lack bass. I was hoping to add a sub that would just fill in some of the missing bass. At first I was going to just buy an Inclosed power subwoofer, but after reading about the Augie's I thought staying with an OB design for the sub also might be the way to go.
If I but both speakers in the same baffle, will I need to add a cap and inductor to the Betsy?
Thanks,
The Decware is an excellent sounding amp, but as sreten suggests, with its limited power, you probably don't want any insertion loss to the Betsy, so a passive HP filter on the amp should be worth considering .
I did a project with a pair of Zen C's over a decade ago (2003, actually), in which passive line level XO's were executed in each amp by the addition of a single cap at the inputs - before the volume pot. This method is simple and dirt cheap, but has the disadvantage of not being easily adjustable for XO point.
The issue with using a plate amp is that their built-in XO's usually top out around 120 to maybe 180, which depending on how narrow you want your OB, may be too low.
Pick an XO point for the Betsy and use the simple PLLXO calculator here TLS.org | Passive Line-Level Crossover to calculate the value of the cap(s)
The Zen has been in production long enough that Steve has made more than a few mods and upgrades, not least among them the retail price. The version that I used had two pairs of RCA input jacks, and a single toggle switch on the top to select between bias points for the input tubes. As I and the owner of the system agreed as to which bias setting we preferred (12 yrs ago, so forgive me if I do forget ), we elected to repurpose that switch to select between rear mounted RCA jacks with the filters, and the top mounted jacks without ( i.e. "full range").
This made for a very neat mod - no outboard box for the PLLXO, extra interconnect cables, minimal increase in signal path, and easily reversible.
Of course, without getting spendy with a separate active XO, you could add some flexibility by fabricating an external PLLXO with several XO points in a small plastic or aluminum hobby case. Unless you're addicted to Mundorf or AudioNote price pointed film caps, the box and associated RCA jacks will likely cost more than the actual filter components.
I did a project with a pair of Zen C's over a decade ago (2003, actually), in which passive line level XO's were executed in each amp by the addition of a single cap at the inputs - before the volume pot. This method is simple and dirt cheap, but has the disadvantage of not being easily adjustable for XO point.
The issue with using a plate amp is that their built-in XO's usually top out around 120 to maybe 180, which depending on how narrow you want your OB, may be too low.
Pick an XO point for the Betsy and use the simple PLLXO calculator here TLS.org | Passive Line-Level Crossover to calculate the value of the cap(s)
The Zen has been in production long enough that Steve has made more than a few mods and upgrades, not least among them the retail price
. The version that I used had two pairs of RCA input jacks, and a single toggle switch on the top to select between bias points for the input tubes. As I and the owner of the system agreed as to which bias setting we preferred (12 yrs ago, so forgive me if I do forget ), we elected to repurpose that switch to select between rear mounted RCA jacks with the filters, and the top mounted jacks without ( i.e. "full range").This made for a very neat mod - no outboard box for the PLLXO, extra interconnect cables, minimal increase in signal path, and easily reversible.
Of course, without getting spendy with a separate active XO, you could add some flexibility by fabricating an external PLLXO with several XO points in a small plastic or aluminum hobby case. Unless you're addicted to Mundorf or AudioNote price pointed film caps, the box and associated RCA jacks will likely cost more than the actual filter components.
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Hi,
Increase the input coupling cap to the Decware amplifier,
to reduce bass level, ideally match it to the baffle hump,
i.e. so response is flat to the peak of baffle hump, and
then rolls off. This will give more dynamic mid output.
What size is the baffle ? It may fill in a Betsy dip.
Sensitivity differences don't matter with active and
vastly different amplifier outputs. The Augies are
ridiculously expensive to go with the Betsy's.
GRS 15PF-8 15" Paper Cone Foam Surround Woofer
Would work well with a quite modest subamplifier being
all that is needed to keep up with 2 watts and the Betsy.
rgds, sreten.
Increase the input coupling cap to the Decware amplifier,
to reduce bass level, ideally match it to the baffle hump,
i.e. so response is flat to the peak of baffle hump, and
then rolls off. This will give more dynamic mid output.
What size is the baffle ? It may fill in a Betsy dip.
Sensitivity differences don't matter with active and
vastly different amplifier outputs. The Augies are
ridiculously expensive to go with the Betsy's.
GRS 15PF-8 15" Paper Cone Foam Surround Woofer
Would work well with a quite modest subamplifier being
all that is needed to keep up with 2 watts and the Betsy.
rgds, sreten.
Take a look at the Zen C schematic on page 11 of the owner's manual http://www.decware.com/zsowner.pdf.
I lost track of the numerous minor changes in the circuit over the years, but I honestly thinks it's remained close enough to this for your purposes.
The Zen has no coupling cap at the signal input, I think sreten is referring to the .01mF cap circled in yellow, between the 47K B+ dropping resistor for input tube, and the junction of 330K and 330R (pin 2) at output tube?
In the procedure described above, I left that cap stock value ( a lot of guys upgrade the quality of this part, often running out of space - not a ton of space under the skirt here), and added the filter cap at the rear panel RCA jack - i.e before the volume pot, and reconfigured the switch to select between the two pairs of inputs.
I lost track of the numerous minor changes in the circuit over the years, but I honestly thinks it's remained close enough to this for your purposes.
The Zen has no coupling cap at the signal input, I think sreten is referring to the .01mF cap circled in yellow, between the 47K B+ dropping resistor for input tube, and the junction of 330K and 330R (pin 2) at output tube?
In the procedure described above, I left that cap stock value ( a lot of guys upgrade the quality of this part, often running out of space - not a ton of space under the skirt here
), and added the filter cap at the rear panel RCA jack - i.e before the volume pot, and reconfigured the switch to select between the two pairs of inputs.Wow, this is a great forum to learn from. Thanks for all your reply's. I just ordered a couple of the GRS woofers. At only $30 a piece I will be able to fund the whole project for less then the cost of 1 Augie. I also ordered a 100 watt Dayton plate amp to power them.
Steve at Decware had made a mod on my SE84 that replaced one pair of the line in jacks with line out jacks. Steve said this would help the subwoofer amp track the SE 84 and that it should help integrate the two amps more smoothly. So I will be using the line in from my source and the line out to feed the subwoofer plate amp. Once I get it setup I will play with the plate amps crossover and volume to try to get the bass I'm looking for.
So, will I still need to but some type of filter on the Betsy? If so can it be done at the speaker? I'm a novice and do not feel comfortable making any mods to the internals of the SE 84.
Thanks,
Steve at Decware had made a mod on my SE84 that replaced one pair of the line in jacks with line out jacks. Steve said this would help the subwoofer amp track the SE 84 and that it should help integrate the two amps more smoothly. So I will be using the line in from my source and the line out to feed the subwoofer plate amp. Once I get it setup I will play with the plate amps crossover and volume to try to get the bass I'm looking for.
So, will I still need to but some type of filter on the Betsy? If so can it be done at the speaker? I'm a novice and do not feel comfortable making any mods to the internals of the SE 84.
Thanks,
rich, how many signal source components are there in your system, and is there a master level control upstream?
I have a lot of respect for Steve, in fact after visiting his room at VSAC2001, one of my first tube amp builds was a shameless mash-up/clones of the Zen and Bottlehead parafeed topology. His ad copy at the time heavily stressed that the amazing performance of his design was not just the simplicity of the circuit, but the very special in-house hand wound OPTs, so any copy of his design with standard transformers would likely lack that secret sauce. Fair enough - they do sound great.
I've also built several kits and DIY tube amps in this general power range, and have experienced both their magic, and their limitations. Which is why I suggest you'll achieve more of the benefits of bi-amping, particularly with any amp of this power level by including a HP filter on its input, rather than with passive components after the amp.
This is very easily accomplished at the RCA jacks, but if Steve's mod tapped and isolated the line out after the volume pot to allow the sub amp to "track" the Zen, that could make things a bit more complicated.
I have a lot of respect for Steve, in fact after visiting his room at VSAC2001, one of my first tube amp builds was a shameless mash-up/clones of the Zen and Bottlehead parafeed topology. His ad copy at the time heavily stressed that the amazing performance of his design was not just the simplicity of the circuit, but the very special in-house hand wound OPTs, so any copy of his design with standard transformers would likely lack that secret sauce. Fair enough - they do sound great.
I've also built several kits and DIY tube amps in this general power range, and have experienced both their magic, and their limitations. Which is why I suggest you'll achieve more of the benefits of bi-amping, particularly with any amp of this power level by including a HP filter on its input, rather than with passive components after the amp.
This is very easily accomplished at the RCA jacks, but if Steve's mod tapped and isolated the line out after the volume pot to allow the sub amp to "track" the Zen, that could make things a bit more complicated.
Sreten, increasing the input cap value does not reduce
bass level. Its other way around...just a detail
Hi, of course, basically a typo I didn't spot, rgds, sreten.
Thanks again for all your reply's. The answer to a few questions that were asked is as follows: The baffle I'm using I bought from Caintuck Audio, it's 22.5" tall and 18" wide.
The only source I'm using is a Bluesound Vault music server. For now I'm using its built I dac. I may upgrade the dac later.
The mod that Steve made to the amp is providing variable line out jacks that I think he said come off the UFO output transformers.
My main concern is that I want the new GRS woofers to blend well with the Betsy's which I really like running as full range drivers.
Thanks,
The only source I'm using is a Bluesound Vault music server. For now I'm using its built I dac. I may upgrade the dac later.
The mod that Steve made to the amp is providing variable line out jacks that I think he said come off the UFO output transformers.
My main concern is that I want the new GRS woofers to blend well with the Betsy's which I really like running as full range drivers.
Thanks,
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