Thanks for your input. The Beymas gave quite satisfactory bass in the Viechs - punchy and dynamic, but not deep.
I'll give 'em a go with the SBs.
I have the same experience with voigt pipes and small horn like the Veich also work as quarter wave resonators in the bass. High Q drivers work OK if the Fr is high or cone is light. The really terrible ones was hevy coned drivers with Fr well below 40 Hz and a high Q. They gave a terrible one note booming bass regardless of music input
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To get a real backloaded horn for 8" drivers you have to get up in size like the old Schmacks horn or that that Norwegian Big Fun Horn, Lowther TP-1 they all are about 500 liters/ 20 qf.
.To get a real backloaded horn for 8" drivers you have to get up in size like the old Schmacks horn or that that Norwegian Big Fun Horn, Lowther TP-1 they all are about 500 liters/ 20 qf.
Not as narrow nor small ;-)...
years ago I built a large back-horn for an 8" fostex driver.
It had amazing bass performance given the driver and sounded very good overall - I sold my Decware HDT speakers (also in the pic) and kept these monsters.
It was called the "RCA-Fan horn" using a slightly modified Fostex FE206E driver and a Karlson slot on the horn mouth exit.
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Wow nice wish that it's meant for a Coral Flat 8. Very nice felt cover on the magnet tooNot as narrow nor small ;-)...
years ago I built a large back-horn for an 8" fostex driver.
It had amazing bass performance given the driver and sounded very good overall - I sold my Decware HDT speakers (also in the pic) and kept these monsters.
It was called the "RCA-Fan horn" using a slightly modified Fostex FE206E driver and a Karlson slot on the horn mouth exit.
Could any of you speaker experts render an opinion on how this driver would perform in my RCA 64-B MI-4400 monitor enclosures?
I can supply more information on the cabinets if anyone is interested.
I have the original drivers, but the cones are in bad shape.
mine are painted flat black for TV studio stage monitors. Supposedly they were used in the studios of the NBC-TV affiliate In Baltimore.
l bought them about 30 years ago and spent years looking for original drivers or someone that could repair them. I gave up and tried an Altec 409 (I think that’s the model # of the driver) full range that was intended for ceiling speakers in office buildings.
I was taken back with the low frequency response! I’m hoping this coax might work well in these enclosures and add some high frequency respons.
anyone care to comment?
Peace,
Technical
I can supply more information on the cabinets if anyone is interested.
I have the original drivers, but the cones are in bad shape.
mine are painted flat black for TV studio stage monitors. Supposedly they were used in the studios of the NBC-TV affiliate In Baltimore.
l bought them about 30 years ago and spent years looking for original drivers or someone that could repair them. I gave up and tried an Altec 409 (I think that’s the model # of the driver) full range that was intended for ceiling speakers in office buildings.
I was taken back with the low frequency response! I’m hoping this coax might work well in these enclosures and add some high frequency respons.
anyone care to comment?
Peace,
Technical
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The horns is similar to Schmacks Isophon but with the horisontal part of the horn path split in two and the driver centrally located. The best driver I have heard for Schmacks was JBL 2110. A driver with a Qt similar to the SB driver but with a higher Fr. The Sb should be a good fit for the bass horn part of the speaker. However I am not sure about those diffusor vanes in front of the driver, they might do more harm than good for a modern driver.
That Altec with a Fr= 84 Hz and probably a very high Q and a very light cone is not an ideal horn driver, so weak and perhaps one note bass is not surpricing.
Any more measurements and pictures on the horn?
That Altec with a Fr= 84 Hz and probably a very high Q and a very light cone is not an ideal horn driver, so weak and perhaps one note bass is not surpricing.
Any more measurements and pictures on the horn?
best bet for such big horns (8 feet horn length) is a driver with low Qts I think.
This SB driver has a higher Qts and doesn't seem designed specifically for a back-horn cabinet.
But does that mean it won't sound good? I don't know.
Some possible other drivers, all much more expensive:
Lii Audio Silver-8
Tang Band W8-1772
Seas FA22RCZ
Fostex FE208NS
Incorrigible me eyeing a newcomer 8" whizzer version of HiFi-bird beige drum-paper 4.5 & 5.5 I liked so much (notch-filtered or mix-stacked). I was hoping for 6.5... Brand being renamed "MKHIFI".
https://item.taobao.com/item.htm?id=586464690797 in Chinese but shows FR chart and Qts~0.5
https://item.taobao.com/item.htm?id=586464690797 in Chinese but shows FR chart and Qts~0.5
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Yikes, didn't used to do that.... Sorry. MKHIFI (new brand name, was HiFi bird or Michael's Audio) 8" (~$140/pr) and 5.5" (~$70/pr). Compay doesn't seem to cater to "looks". Translated from blurbs: company HiFi bird founded 1991 by Redmond Reebok, HQ'ed Kent, England. Chinese names "cooperative birds" or "birds joined forces". Innovative use of very thin, imported English "drum paper" with "nanometer" coating.Nobody can see this link so ...
the link requires you to register.
The 5.5" (labelled as 6), 4.5" (labelled as 5), and 4" (labelled as 4) are/were sold by several China online retailers with or without cabs; the 8" is recent and (as far as I know) sold by one new shop driver-only.
(I started with the 4.5" in piano black cabs, upped to 5.5", just ordered a spare pair of drivers, and will probably try the 8".)
BTW, the SB20FRPC30 can't be found on taobao or idlefish (China's eBay).
(I started with the 4.5" in piano black cabs, upped to 5.5", just ordered a spare pair of drivers, and will probably try the 8".)
BTW, the SB20FRPC30 can't be found on taobao or idlefish (China's eBay).
I have just ordered a pair of SB FR 8 inch from Willy’s HiFi - I am UK based. After much deliberation I am going to keep it simple and will produce something inspired by the Omega Super 8 XRS - effectively just an FR driver in a well thought out cabinet.
I have modelled in WinISD and a 40 litre sealed cabinet with a QTC of 0.706 gives and F3 of 67hz. The cabinet will be window braced, 35 mm egg crate open cell foam applied to all internal surfaces and possibly mass-loaded at the bottom in a sealed chamber for stability - I will use something like Atabites. The cabinet will be made from 18mm MDF with painted sides and top but veneered front and rear. The plan will be that they end looking something like this:
I have modelled in WinISD and a 40 litre sealed cabinet with a QTC of 0.706 gives and F3 of 67hz. The cabinet will be window braced, 35 mm egg crate open cell foam applied to all internal surfaces and possibly mass-loaded at the bottom in a sealed chamber for stability - I will use something like Atabites. The cabinet will be made from 18mm MDF with painted sides and top but veneered front and rear. The plan will be that they end looking something like this:
If necessary I will build some bass ‘modules’ using the SB Acoustics SW26SFC38-8 Shallow Subwoofer and amplification with crossover and phase adjustments. I tend the prefer the flexibility of this approach.
TBH, from an aesthetic point of view, I haven’t been overly keen on the look of many transmission line speakers with FR drivers - they don’t quite look like furniture to my eyes. These speakers will be used in our ’family sun room’ so visuals are very important. I did model a PR version using the matching 8 inch PR and I found that the cone excursion of both the PR and the driver was rather alarming below 50hz or so. From memory I think F3 was lowered by about 10hz but I didn’t think that was sufficient to risk too much cone excursion - I thought I would leave that to dual 10 inch subwoofers if I need them.
FYI, I recently spotted some other cabinet designs that should work well with this driver - take a look at this post where I'm trying to get confirmation that these cabs will work OK. I'm finding more of these cabinets by searching for cabs that work with the very similar driver (which no longer exists) called the Hemp Acoustics FR8C.
