In re the baffles these were the originals: http://web.mac.com/scress1958/iWeb/Steves_Tube_Trials/FostexFest.html -scroll down a way, past the horns
And here for the latest version, next to JamesD's perspex Quasars: http://web.mac.com/scress1958/iWeb/Steves_Tube_Trials/EggFest_4_2.html -again from my friend Steve's site.
And here for the latest version, next to JamesD's perspex Quasars: http://web.mac.com/scress1958/iWeb/Steves_Tube_Trials/EggFest_4_2.html -again from my friend Steve's site.
HEMP or is it HEMP?
Hello everyone just thought I would drop in for a bit.
This is for G and everyone else I noticed that G's specs and he used the model Hemptone. Im not sure where G got his drivers but that not our specs nor our model name the old version was the FR8DIY the new version is the FR8C.
There already has been knock offs so beware.. inlcuding people claiming to have hemp based cones.. using Manilla Hemp. Manilla Hemp is not acutally Hemp ie Cannabils nor does it have the same properites..
Furthmore for the guys on the other side of the pond..we just offically opened HEMPAcoustics Europe which will be distributing ot our current and future dealers all across Europe.
For now we have a couple they are listed on our website with quite a few more in the netherlands, Denmark the UK opening soon..
Just a head up.. and another thank you...
Hemp Acoustics
Hello everyone just thought I would drop in for a bit.
This is for G and everyone else I noticed that G's specs and he used the model Hemptone. Im not sure where G got his drivers but that not our specs nor our model name the old version was the FR8DIY the new version is the FR8C.
There already has been knock offs so beware.. inlcuding people claiming to have hemp based cones.. using Manilla Hemp. Manilla Hemp is not acutally Hemp ie Cannabils nor does it have the same properites..
Furthmore for the guys on the other side of the pond..we just offically opened HEMPAcoustics Europe which will be distributing ot our current and future dealers all across Europe.
For now we have a couple they are listed on our website with quite a few more in the netherlands, Denmark the UK opening soon..
Just a head up.. and another thank you...
Hemp Acoustics
Aswers
Sorry, I've not looked at this thread for couple of days. Here are some answers:
Dave:
1. Drivers were measured with SoundEasy, using MLS. I had a 500 Ohm resistor in series with the driver for all impedance data. Vas was determined using delta mass method with about 30 gramms added to the cone.
2. FR measurements were done as installed in the horn, as described in the Info Package.
Estes,
I am not sure the Hemp is better balanced by itself, than other drivers. There is still a rize to Fr from 1 to almost 8 kHz. It looks like the new FR8C is better in this regard, but I don't have them yet...
The point of my horn design was to use (relatively) high Q of the Hemp driver to balance lower mid and higher bass against this rize in the upper midrange. I think it does what I've hoped for without any BSC.
That said, when I compare these horns with my reference system (based on Manger), I can clearly hear the remaining colourations. They are only apparent in direct A/B comparison. On their own the horns sound very pleasant (to me).
I also listen mainly to classical and jazz and that's what was used to voice them. Currently I drive them with Fisher X-100-B restored amp with nominal 24 wpc. 12 o'clock position is enough to sound VERY loud in my room. The lower midrange is full of meat in this arrangement. You better keep them away from back wall and corners with the amp like this. With SS amp (I've used Adcom) the sound is still full, if a bit driyer. Moving speakers a bit closer to the back wall practically brings the balance back. In either case the imaging is very good.
I've heard Lowthers in some kind of horns several years ago, but not sure they were Medalions or not, so I'll refrain from comparisons. I've heard several different Omega BR speakers using the same driver and I think the horn is better, sounding more dynamic and live, with reacher midrange. Obviously, my opinion is not impartial, also I frequently tend to suspect my own speakers with problems others don't hear.
VadimB.
Sorry, I've not looked at this thread for couple of days. Here are some answers:
Dave:
1. Drivers were measured with SoundEasy, using MLS. I had a 500 Ohm resistor in series with the driver for all impedance data. Vas was determined using delta mass method with about 30 gramms added to the cone.
2. FR measurements were done as installed in the horn, as described in the Info Package.
Estes,
I am not sure the Hemp is better balanced by itself, than other drivers. There is still a rize to Fr from 1 to almost 8 kHz. It looks like the new FR8C is better in this regard, but I don't have them yet...
The point of my horn design was to use (relatively) high Q of the Hemp driver to balance lower mid and higher bass against this rize in the upper midrange. I think it does what I've hoped for without any BSC.
That said, when I compare these horns with my reference system (based on Manger), I can clearly hear the remaining colourations. They are only apparent in direct A/B comparison. On their own the horns sound very pleasant (to me).
I also listen mainly to classical and jazz and that's what was used to voice them. Currently I drive them with Fisher X-100-B restored amp with nominal 24 wpc. 12 o'clock position is enough to sound VERY loud in my room. The lower midrange is full of meat in this arrangement. You better keep them away from back wall and corners with the amp like this. With SS amp (I've used Adcom) the sound is still full, if a bit driyer. Moving speakers a bit closer to the back wall practically brings the balance back. In either case the imaging is very good.
I've heard Lowthers in some kind of horns several years ago, but not sure they were Medalions or not, so I'll refrain from comparisons. I've heard several different Omega BR speakers using the same driver and I think the horn is better, sounding more dynamic and live, with reacher midrange. Obviously, my opinion is not impartial, also I frequently tend to suspect my own speakers with problems others don't hear.
VadimB.
Re: Aswers
This uses the sound card's output to driver the speaker?
If that is the case you will have the same low V situation i have with Fuzzmeasure: the low voltage computer based. T/S measuring kit produces higher Fs, Qts, & lower Vas values than techniques that use higher voltage drive. Factories will usually provide data measured in the 1 V range, vrs computer lit in the mV range. If the factory data isn't different than measured data then something is likely wrong.
In a sealed box the parameter changes pretty much wash out, but in tuned boxes one has to keep in mind the changing parameters as the wick is turned up.
dave
VadimB said:
This uses the sound card's output to driver the speaker?
If that is the case you will have the same low V situation i have with Fuzzmeasure: the low voltage computer based. T/S measuring kit produces higher Fs, Qts, & lower Vas values than techniques that use higher voltage drive. Factories will usually provide data measured in the 1 V range, vrs computer lit in the mV range. If the factory data isn't different than measured data then something is likely wrong.
In a sealed box the parameter changes pretty much wash out, but in tuned boxes one has to keep in mind the changing parameters as the wick is turned up.
dave
Measuremens
Dave,
The output of sound card goes to the power amp in my SoundEasy set-up. The resistor is connected between the + of the amp and the + of the driver. SoundEasy uses two channels: Reference probe is connected before the resistor to the output of the amp, the "In" probe is connected to the driver, after the resistor. The resistor can be as low as Re, but I preffer the higer values, to be closer to a constant current source. This is a classic T/S set-up dating back to T and S themself. After all, T/S models are valid for a "small signal parameters". I did compare the data with 500 Ohm resistor and with 12 Ohm resistor, and they are close enough, if the voltage across the driver is kept close.
SoundEasy alows to do a non-linear models of the driver, but I have not gone that far yet.
In my experience, drivers measure close to the "small-signal" at higer signals, after they are broken-in for a while.
VadimB
Dave,
The output of sound card goes to the power amp in my SoundEasy set-up. The resistor is connected between the + of the amp and the + of the driver. SoundEasy uses two channels: Reference probe is connected before the resistor to the output of the amp, the "In" probe is connected to the driver, after the resistor. The resistor can be as low as Re, but I preffer the higer values, to be closer to a constant current source. This is a classic T/S set-up dating back to T and S themself. After all, T/S models are valid for a "small signal parameters". I did compare the data with 500 Ohm resistor and with 12 Ohm resistor, and they are close enough, if the voltage across the driver is kept close.
SoundEasy alows to do a non-linear models of the driver, but I have not gone that far yet.
In my experience, drivers measure close to the "small-signal" at higer signals, after they are broken-in for a while.
VadimB
MLTL vs Horn dynamics
Salas,
to be able to really compare the two, we need to put them together, side by side, and listen. Unfortunately, we live on the different sides of the Ocean. I would love to visist you, but taking the horns with me would be a bit of a problem. I've listened to medium size BR with Hemps though, and the difference in dynamics was quite apparent. Othervise, they did sound balanced and transparent.
VadimB
Salas,
to be able to really compare the two, we need to put them together, side by side, and listen. Unfortunately, we live on the different sides of the Ocean. I would love to visist you, but taking the horns with me would be a bit of a problem. I've listened to medium size BR with Hemps though, and the difference in dynamics was quite apparent. Othervise, they did sound balanced and transparent.
VadimB
Re: measurements
For impedance measurements, it really depends on the size and power of the driver. For something like Hemp 8, it would be around 350 mV across the driver.
FR measurements are done without a resistor. "Ref" probe goes on the input of the driver, "In" probe is connected to the output of mic preamp. For this I keep the output power at 1W, if the mic is at 1m. Radio Shack SPL meter is used alongside for an absolute SPL scaling.
VadimB
For impedance measurements, it really depends on the size and power of the driver. For something like Hemp 8, it would be around 350 mV across the driver.
FR measurements are done without a resistor. "Ref" probe goes on the input of the driver, "In" probe is connected to the output of mic preamp. For this I keep the output power at 1W, if the mic is at 1m. Radio Shack SPL meter is used alongside for an absolute SPL scaling.
VadimB
resident said:ok since I don't like to go with a horn (to complex to build), it's my first fullrange project and Hemp seems a good driverI think I'll build the wide baffle MLTL that has been disgussed here.
Can you tell me which dims to follow? Scott's or GM's?
Which are the differences?
Can't tell who's dimensions you may prefer, bcs we made it different, normally wide for an 8inch. And used a notch incorporating some BSC. So its another thing altogether. Plus followed my own measurements using WT2 on well run in Hemp.
Attachments
salas,
you didn't understand my question!
I didn't ask which I will prefer but as a newbie I'd like to know the differnces btw a bigger MLTL (GM) than a smaller one (Scottmoose).
Notch filter is not always needed. It depends on the room and the speakers placement....
Can you post your Hemp project's dims?...........................
Looks nice in the pic.
you didn't understand my question!
I didn't ask which I will prefer but as a newbie I'd like to know the differnces btw a bigger MLTL (GM) than a smaller one (Scottmoose).
Notch filter is not always needed. It depends on the room and the speakers placement....
Can you post your Hemp project's dims?...........................
Looks nice in the pic.
I can't post dims or filter because its property of a friend who owns a small scale specialist company named Silvernote. I just helped out. But its good. Its smaller than the wide baffle schemes proposed here. These must work better, not needing BSC. The 'Solo' as it is called, measures 30Hz-18K +/- 2dB in room. A major audio press journalist here used it as reference to publish tube amp group tests.
Re: Re: Re: measurements
Dave,
The factory data, like those posted, were published by Hemp, probably, a year before they anounced merger with Adire. On the other hand, Hemp Acoustics is a spin-off from a very large and reputable company and they certainly know how to measure drivers. You can see that by the format of the data in their PDF files.
That said, whatever the method you use for impedance measurement (even pure analog) - you still need a series resistor. The old analog standard was to use a 1000 Ohm resistor and have 1 V across the driver + resistor. In this case, voltage across the driver at 1 kHz is under 10 mV.
I generaly keep the output of the amp around 1 W of power. With my 500 Ohm resistor this translates to about 320-350 mV across the driver. Different drive levels will no doubdt result in some difference in T/S parameters.
On the other hand, I'm sure you know that T/S is not everything. Over the years I just developed a filling on what I'm going to get, designing for some T/S. That's why I try to keep my T/S measurements consistent in all my projects. This definitely does not mean that my way of measuring them is the best, or the only right one.
There was a very interesting and useful discussion about that in the SoundEasy user group about a year ago, between John K and several other people. Lots of data were presented. Try to search the archive, or I'll see if I saved some of that when I get home.
VadimB.
planet10 said:
Dave,
The factory data, like those posted, were published by Hemp, probably, a year before they anounced merger with Adire. On the other hand, Hemp Acoustics is a spin-off from a very large and reputable company and they certainly know how to measure drivers. You can see that by the format of the data in their PDF files.
That said, whatever the method you use for impedance measurement (even pure analog) - you still need a series resistor. The old analog standard was to use a 1000 Ohm resistor and have 1 V across the driver + resistor. In this case, voltage across the driver at 1 kHz is under 10 mV.
I generaly keep the output of the amp around 1 W of power. With my 500 Ohm resistor this translates to about 320-350 mV across the driver. Different drive levels will no doubdt result in some difference in T/S parameters.
On the other hand, I'm sure you know that T/S is not everything. Over the years I just developed a filling on what I'm going to get, designing for some T/S. That's why I try to keep my T/S measurements consistent in all my projects. This definitely does not mean that my way of measuring them is the best, or the only right one.
There was a very interesting and useful discussion about that in the SoundEasy user group about a year ago, between John K and several other people. Lots of data were presented. Try to search the archive, or I'll see if I saved some of that when I get home.
VadimB.
resident said:
Greets!
At the risk of sounding biased, my guideline is that the bigger the cab, vent, the more tuning flexibility it has, so based solely on this, mine would be the choice. If you have a relatively small room and/or will be putting them near corners though, then Scott's might save you from having to do any vent testing.
Your call......
GM
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