Clone of PMC DB1+ ???

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#3
Inside pic
 

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#4
I did a similar build here using similar drivers.
They sound good but I think they could have been as good (or better) with a simple ported box, avoiding some build and design complexity.
The advantages of TL are realized with larger midbass drivers and boxes.
 
#5
My first DIY speaker was a ported box:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=138195&highlight=

but it's a full-range, so the bass is limited. However, the real issue is that I find that the PMCs have a smoother response, I can listen to them for much longer without fatigue and they give up only a very little in the way of high end detail against the Onken's.

Since my existing PMCs are a TL design I am wondering if this approach is partly responsible for the smoother sound, or if it is the drivers. I still have to try out some of the cone treatments recommended by Dave (planet10) to tame the high end a bit but I feel a new project coming on later this year involving a stereo amp design and a new pair of DIY speakers. Which direction to go for clean, smooth and decent low end ?
 
#7
Bigun said:
, the real issue is that I find that the PMCs have a smoother response, I can listen to them for much longer without fatigue and they give up only a very little in the way of high end detail against the Onken's.
Click to expand...

That is almost surely all on the big 7 kHz peak inherent to the FE127e. Pretty easier to reduce that issue dramatically.

dave
 
#8
planet10 said:
Here is a dimensioned drawing based on the pdf of post 2.

Perhaps someone with MJK could model the line (assumming that the drive ris a stock VIFA and not a custom OEM)

dave
Click to expand...

I'm definitely interested in this option, if somebody would like to help model it I would be most grateful. If the design ideas progress well there's a good chance I will build it. But this is beyond my ability to design and so I need some help.

The goal should be the best darn small-box DIY speaker ever made with a clean, smooth musical sound and enough bass to keep folks happy with the smaller box :smash:
 
#12
I guess PMC have some arrangements to semi-customize the drivers and so they own the particular model variant that they use.

Question is whether to use the closest relative, or strike out and pick a different pair of drivers with the aim to maximize the sound quality. The latter seems risky but if the closest available relatives of the PMC drivers are not close enough then that could be an even worse situation.

I've looked around to see if anybody else has trodden this path, so far it's a lonely path. One reference but it's old and not very informative [http://www.gearslutz.com/board/geekslutz-forum/114230-my-pmc-inspired-monitor-build.html]

This [http://www.markaudio.com/plan/alpair-5-desktop-tl] on the other hand looks really nice. It's a full range and likely misses a lot of the bass compared with the PMC but shows how a small folded TL can be done well in a great desktop size. Perhaps an Alpair driver would be a good alternative to the Vifa ???
 
#13
oh my gosh, clones they do have !

http://www.ornec.com/Von_Masoch_TB2_Bookshelf_speakers_QQC100111A

If TL demands quite different drive unit parameters compared with a standard unit and many of PMC's drive units are actually custom designs produced with significantly different specifications then these clones are probably not like the real thing.

I wonder if there's even a TL inside the box :whazzat:

anyhow, getting more information as I search.

Attached is the XO design...
 

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#15
I don't know if the HDS exclusive would work.

I think you should ask tymphany for a spec sheet of the M13WG and maybe it isn't too different to the SG version. (fs should be the same)

Question to all: What parameters are really crucial for a ATL design besides "sd"?
 
#16
burnett said:
I don't know if the HDS exclusive would work.

I think you should ask tymphany for a spec sheet of the M13WG and maybe it isn't too different to the SG version. (fs should be the same)

Question to all: What parameters are really crucial for a ATL design besides "sd"?
Click to expand...


I can relax the requirements that it be an exact clone, afterall, eBay could likely turn up a pair of DB1's if I were really needy. I like the FB1's and I have never built a two-way, and find the concept of TL very interesting but it seems it would be lower risk to clone an existing design than try to get right first time the 'black art' of two-way TLs. I'm looking for something that can work a larger room than my Fostex 127E's and without a sub - the TL is my choice for deep and powerful bass.

If there is a proven DIY 2-way TL design out there that is similar to the DB1 in size then I'd be most excited to hear about it ? - if not, I am pretty much at the mercy of this forum to learn how to get where I want to go 🙂
 
#17
Did anyone check this out before ?

http://vids.myspace.com/index.cfm?fuseaction=vids.individual&VideoID=55250566

A video by PMC talking about their TL technology. Some of the claims include a special foam filling that works over a broader frequency range than what other people use and allows them to retain the performance over a wider volume range too.

Any thoughts on what is special about the foam and whether I could find something suitable to use for my own design ?
 
#18
Well, I need to resurrect this thread and ask you for some help.

My home theatre system is driving the need. It was supposed to be all single driver full-range speakers and I made a bunch of them for this purpose. But it all changed over time. I now have PMC FB1s for L and R front and at the rear I have B&W CM-4's (which I just got as flood damaged throw-aways and I am currently repairing the tweeters). The front centre speaker is still a DIY single driver unit and it simply can't provide anything like a match to the rest of the system.

Ideally I would want the centre speaker to match the front L and R speakers, which implies that I need an FB1 clone. My set up allows me to use a vertical oriented centre speaker sitting on the floor. Using a full size FB1 would be too large, but I can accommodate something that is half the height of an FB1.

The original subject of this thread was a DB1 clone which is even smaller than half an FB1 - still, they use the same drivers and this is my starting point...

For matching the sound of the centre with the PMC FB1s I need your updated advice on the drivers. I'll need a tweeter and a mid-bass driver. The question is which drivers should I buy given that the original PMC drivers are either obsolete or were custom made for PMC and not available to me. I realize exact matching is not possible, but I expect it's possible to come up with something that's a far better match than my current centre speaker.

????
 
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#19
What you could try is a TB2-C (the center version of the TB2) as they have the same drivers as the FB1.
There is a recent thread where I posted some plans of the TB2 and you could use a second hand Vifa M17WG or try a Seas CA18RLY (very very similar) as mid-woofer. Tweeter is the Vifa D27 (also available as a Scan Speak Discovery Version D2606/922000).
 
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