Hello Christian.
The proplex does not show any peaks on my frequency response plot, but that does not mean that they are not there hidden below the frequancy response plot level.
My 3mm ply panels suffered the peaks from the central coil area which I used various methods to reduce or remove the problem.
Using foam to damp the peak did very little to remove the peak, so I filled the 2mm hole with blu-tack ( previously I had used blobs of blu-tack to damp the coil area, but I did not like the sound of added mass), I seem to remember this worked quite well, but I can't remember posting these results?
Heavy ply panels have not been a priority for me.
The strip of paper technique did cure the peak problem in the central coil area, but not necessarily on the panel surface.
I finally decided that I preferred to use a polythene sheet membrane as a passive drive mechanism, this solved most of the problems with 3mm ply and come to that the proplex panel as well.
I did not Finnish these experiments, and left it there for others to experiment with ,if they desired.
Steve.
The proplex does not show any peaks on my frequency response plot, but that does not mean that they are not there hidden below the frequancy response plot level.
My 3mm ply panels suffered the peaks from the central coil area which I used various methods to reduce or remove the problem.
Using foam to damp the peak did very little to remove the peak, so I filled the 2mm hole with blu-tack ( previously I had used blobs of blu-tack to damp the coil area, but I did not like the sound of added mass), I seem to remember this worked quite well, but I can't remember posting these results?
Heavy ply panels have not been a priority for me.
The strip of paper technique did cure the peak problem in the central coil area, but not necessarily on the panel surface.
I finally decided that I preferred to use a polythene sheet membrane as a passive drive mechanism, this solved most of the problems with 3mm ply and come to that the proplex panel as well.
I did not Finnish these experiments, and left it there for others to experiment with ,if they desired.
Steve.
Hans,
I ordered a t-racks DPS 4x4 mini, thanks for the suggestion. Had to pay 55% import tax, but did it anyway. That s**ks.
I didn't order any new amps yet. I'd like to just play around with the dsp for now. But if I do get some amps I'm leaning toward a pair of the Fosi V3 amps, with the 48/5 power supply.
Thanks to all for their suggestions.
Eric
Hi Eric,
The import tax make it less of a great deal...but still not too bad price wise.
The device comes with software on an archaic mini-cd rom, but you can also download the software from the Thomann product page. It runs in "demo" mode in case you already want to play with it a bit. I hope (and think) you will like it.
Greetings, Hans
The import tax make it less of a great deal...but still not too bad price wise.
The device comes with software on an archaic mini-cd rom, but you can also download the software from the Thomann product page. It runs in "demo" mode in case you already want to play with it a bit. I hope (and think) you will like it.
Greetings, Hans
That amp is nice but is only 2 channel, here is their cheapest 2.1 50w at $80 US right now... https://www.amazon.com/Bluetooth-Audio-Amplifier-Integrated-BT30A-Silver/dp/B07K7NJ4QN/ref=sr_1_4?crid=1OI9KFFTD4AH0&dib=eyJ2IjoiMSJ9.GJ5S8-t7o1v_BGXfNDaftMp__MG5ipD8u_qRwdSZ9vIdegTnJ1dV2cxTsIbBS-DH4ePvrZiA30WrOab4We3K68iW4jQHlnysyydUz59ZIPtFwWSNxByT-zxcS3GjiSz1I3LMNGju9yL3S13Bra8LOCwGJzI-diBrkgOcri0AsFE0WLnTW7GhBSIOHUste6RX4Vt667-rq4imAO1vg1VoxAFuBbnlamTFOJ2e6hou570.t9syvJwtn2En_Ym7Kn9x5Yylulzo3uohebcKHyKVesI&dib_tag=se&keywords=fosi+2.1+amplifier&qid=1750524157&sprefix=fosi+2.1,aps,161&sr=8-4
Hi Christian
I'm late to this as I tend to follow this thread somewhat erratically. Yes, I've used a panel in conjunction with both an asymmetrical semi-topless U frame and an H frame bass unit (using a Monacor SP-382PA driver). I use a miniDSP Flex for preamp and DSP purposes and typically tune my overall response to the RTINGS curve. The bass plays strongly down to 30hz then falls off rapidly.
My DML panel is 2mm 60x40cm Ceiba plywood rigidly attached to a wood frame using pieces of 6mm thick foam glued to the plywood and the frame. I'm now using Xcite exciters. Top end performance is better than my cheapo exciters.
I'm now pondering experimenting with Proplex panels but am wondering what thickness to try. 2mm thick stuff is easy to find here.
@spedge
Steve, have you had any more thoughts on using Proplex or similar fluted polypropylene? Wickes do a 2400x1200 sheet of the 2mm thick stuff for £5.60.
My current panel is a 60x40cm bit of 2mm ceiba plywood semi-rigidly attached to a wood frame with spaced bits of 6mm thick foam glued to panel and frame. I'm using Xcite exciters which are a cut above what I was using before.
Bass duties are taken care of by H frame units with 15" drivers. Crossover & DSP is done via the miniDSP FLEX, with overall tuning to the RTINGS curve.
Steve, have you had any more thoughts on using Proplex or similar fluted polypropylene? Wickes do a 2400x1200 sheet of the 2mm thick stuff for £5.60.
My current panel is a 60x40cm bit of 2mm ceiba plywood semi-rigidly attached to a wood frame with spaced bits of 6mm thick foam glued to panel and frame. I'm using Xcite exciters which are a cut above what I was using before.
Bass duties are taken care of by H frame units with 15" drivers. Crossover & DSP is done via the miniDSP FLEX, with overall tuning to the RTINGS curve.
Long time you posted here!
Nice to see you continue with DML. Thank you for your answer.
I am thinking to a similar arrangement. Not that wide because for my room the target is more 30 to 35cm wide and deep
I am also wondering the result of a PassLab SLOB. The bass driver has a vertical axe and is mass loaded by the air trapped just below. I don't remember checking the FR... is it able of 200Hz?
Yes Steve (@spedge is our reference with Proplex. If my memory is correct, he was happy with the 6mm thickness but the most important was the rounded flutes.
Common polypropylene fluted sheets are with square flutes here. Steve was not satisfied of it and the little experience I had don't put it at the top of the materials.
The drawback of this material is the rather low efficiency.
Christian
@homeswinghome
Yes, I thought it time for another bit of input!
For SLOB, take a look at ABXaudiophile on youtube. Their 'double C' SLOB has rave reviews. I considered it, but since my Monacor drivers have an Fs of 25hz and QTS of 0.75, I decided that an H frame made more sense.
The minidsp makes active crossovers and DSP very easy, in conjunction with a calibrated mic and REW. I'll post some pictures and response curves when I'm on the other PC.
BTW, my room is only 4.15x3.6xx2.7m. I use a pair of Aiyima A07 amps, one per side, with each amp split into Bass and DML sections. Channel separation is excellent!
Yes, I thought it time for another bit of input!
For SLOB, take a look at ABXaudiophile on youtube. Their 'double C' SLOB has rave reviews. I considered it, but since my Monacor drivers have an Fs of 25hz and QTS of 0.75, I decided that an H frame made more sense.
The minidsp makes active crossovers and DSP very easy, in conjunction with a calibrated mic and REW. I'll post some pictures and response curves when I'm on the other PC.
BTW, my room is only 4.15x3.6xx2.7m. I use a pair of Aiyima A07 amps, one per side, with each amp split into Bass and DML sections. Channel separation is excellent!
I think you mean SLOB from the family below (this is the smallest... bookshelves!) In one video, it was running without the wings.
Have you already found some technical input in the woofer parameters change due to the slot?.
I guess the the fs is going down due to the air mass in front. Not sure...
From a pure use of the space point of view, I prefer the PassLab architecture below (link in the post just before). It let also almost the full front face for the DML.
But their are maybe even other arrangement possible... This gives ideas...
@homeswinghome
Not found any data as such. However, the slot loading is supposed to lower Fs and raise QTS. For OB bass, a QTS of >0.7 is desirable. My preference would really be for a pair of 12" bass drivers per channel. However, finding decent low Fs plus high QTS drivers at sensible money is hard.
Not found any data as such. However, the slot loading is supposed to lower Fs and raise QTS. For OB bass, a QTS of >0.7 is desirable. My preference would really be for a pair of 12" bass drivers per channel. However, finding decent low Fs plus high QTS drivers at sensible money is hard.
@homeswinghome
As promised, some frequency response curves from my H frame / ply panels. They are tuned to an in-room RTINGS response curve. I may reduce the bass a bit as it's 1-2db too strong.
As promised, some frequency response curves from my H frame / ply panels. They are tuned to an in-room RTINGS response curve. I may reduce the bass a bit as it's 1-2db too strong.
Attachments
I might have 2 kind of pair of candidates here. 2 of those woofers are 15" not really usable in classical loads... Hmm.. a job for hornresp?
I understand
Impressive!
I didn't have in mind a Rtings house curve.
Here is ASR thread A collection of speaker target responses in .csv/.txt format comparing the different house (or in-room) curves.
Which IR window do you use in REW for that?
I just used random pink noise and ran it for about 100-150 samples. I used to use the ,moving mic method', but found a central position gave me the same results.
I also tried the Harman curve (same source as the one you mention), but found it a little lacking in the lower midrange.
I'm thinking of trying something other than ceiba ply. The sound is very 'safe', but lacks some transparency. Perhaps the ply is 'slower' than say EPS or Proplex leading to masked leading and trailing edges. It seems frequency response isn't everything!
Whatever panel material I decide on, I may try the late, great Zygadr's cloth tape mounting method.
I've lost track of Steve's (@spedge ) preferred damping method for EPS. I think it's sand both sides and apply 50/50 PVA/water to both sides. I just need to decide on EPS grade. Zygadr used to promote ultra high density stuff, whilst I think Steve prefers lower grades. I may hedge my bets and go for EPS100 which is one rung above standard EPS70.
I also tried the Harman curve (same source as the one you mention), but found it a little lacking in the lower midrange.
I'm thinking of trying something other than ceiba ply. The sound is very 'safe', but lacks some transparency. Perhaps the ply is 'slower' than say EPS or Proplex leading to masked leading and trailing edges. It seems frequency response isn't everything!
Whatever panel material I decide on, I may try the late, great Zygadr's cloth tape mounting method.
I've lost track of Steve's (@spedge ) preferred damping method for EPS. I think it's sand both sides and apply 50/50 PVA/water to both sides. I just need to decide on EPS grade. Zygadr used to promote ultra high density stuff, whilst I think Steve prefers lower grades. I may hedge my bets and go for EPS100 which is one rung above standard EPS70.
Using the moving mic method, I came to the same observation. There is not much change from the central position when the measurement area is enlarged.
Could you remind me what it is ? I am thinking about solution using some sort of fabric for the suspension. It is terrible how a simple string or ribbon can sing!
The main think I learnt from exchanges with Steve is "not go to fast in the material modification (alteration?)". Glue the exciter on it and listen and if possible measure. Then move to a modification. So for example apply PVA on back but not on front.
Use PVA to glue the exciter on the panel. Wait maybe one day ore more it dries. The PVA is strong enough to transmit the full frequency range but allow to get the exciter back with no damage.
An other advice I get from Steve : Be minimalist in the changes to the panel or the suspension elements (I hope I report correctly his recommendations)
@spedge : please comment if necessary.
Keep material for more than a pair. It's easy to go a step to far.
Think about the central area treatment (shared some posts ago).
One important finding for me was to understand a spine can create a mask at the rear that reinforce some area in the medium.
All of that said, I don't have for now a full design reaching all my thoughts...
Christian
My understanding is that one has an oversized frame e.g. with internal measurements of 70x50cm for a 60x60cm panel. One then uses self-adhesive cloth tape (like gaffer tape) - so for 50mm wide tape 20mm is stuck to the panel material, 5mm gap then 25mm stuck to the frame. The tape is put on the front. The tape is on each complete side i.e. no gaps.
I've just unstuck my exciter from the rear spine and rebalanced the drivers. It seems much improved, so I may delay the EPS. I was never 100% happy when I tried it before. The Xcite 25mm exciters really are rather good - treble extends comfortably to 20khz and beyond even on my ply panels.
Can you please share how low your 60x40 cm panels play before they start to roll off (from the average level above say 100 Hz. or so)? Thank you.
Thank you. I see the principle now. A gap between the panel and the frame (ie 5mm so a 70x50cm internal frame dimension for a 60x40cm panel.) and some tape as suspension.
Somebody reported here some months ago (sorry no time right now to make research on the according post) this method. The main point I have in mind is the possible noise from the tape.
I have used some cloth tape here as central top suspension for panel test. On an EPS panel PVA coated the adherence is enough for short test term but not for long term use.
I've started using 40mm wide 3mm thick foam tape for suspending my panels, to have a 5-10mm gap and give some damping, plus no buzzing as I imagine could be an issue with cloth tape. Not sure how the adhesive will last long term yet. This has been an easy method that gives a good result for me.