A new summer project in the works..... The SB Acoustics drivers just came in the post from Intertechnik - SB20PFC30-8 8" Woofers.
The build quality is simply amazing for the cost of these babies!!! I am more than excited to finally give these budget drivers a try.
I am going for a 2-way bookshelf design with the HiVi isodynamic RT2C tweeters crossed to the SB woofers somewhere between 4.5 - 5k. Thanks to another diyaudio member, who was kind enough to sell me the tweeters🙂
More to follow.....
The build quality is simply amazing for the cost of these babies!!! I am more than excited to finally give these budget drivers a try.
I am going for a 2-way bookshelf design with the HiVi isodynamic RT2C tweeters crossed to the SB woofers somewhere between 4.5 - 5k. Thanks to another diyaudio member, who was kind enough to sell me the tweeters🙂
More to follow.....
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Woofer seems sensitive enough but you'll need some kind of small midrange imo. Not quite buying that off axis response.
That's pretty normal efficiency for an 8-ohm woofer, after BSC probably be 84-85db.
Good combo, those SB's have really nice surprising deep base and nice mids for the price. I have used the 5" and 6" versions and was impressed. Not sure how accurate the FR is, might need a mid in teh mix??
Good combo, those SB's have really nice surprising deep base and nice mids for the price. I have used the 5" and 6" versions and was impressed. Not sure how accurate the FR is, might need a mid in teh mix??
Be sure to measure both ribbons and verify that their response is similar.
I bought Dayton's clone of that driver and the performance varied from unit to unit.
Admittedly, they were purchased a few years apart.
I bought Dayton's clone of that driver and the performance varied from unit to unit.
Admittedly, they were purchased a few years apart.
"RT2C tweeters crossed to 8" SB woofers somewhere between 4.5 - 5k" is unusual.
Experts like Troels Gavensen use an 8" woofer + 4" midrange + 1" dome tweeter. Have you modeled adding a 4" midrange for a 3-way?
SBAcoustics-3WC
To create a smooth controlled directivity pattern, an 8" woofer is often mated to a 1.2" - 1.5" dome tweeter in a waveguide with a 1.3-1.5kHz crossover.
Experimenting with cutting the baffle to create a deeper waveguide for the HiVi isodynamic RT2C (similar to the RT2H-A) could help support an "acceptable" 1.6-1.7kHz crossover frequency to the 8". This would generate a smoother directivity pattern, and reduced lobing. Plus create a closer physical time delay.
Experts like Troels Gavensen use an 8" woofer + 4" midrange + 1" dome tweeter. Have you modeled adding a 4" midrange for a 3-way?
SBAcoustics-3WC
To create a smooth controlled directivity pattern, an 8" woofer is often mated to a 1.2" - 1.5" dome tweeter in a waveguide with a 1.3-1.5kHz crossover.
Experimenting with cutting the baffle to create a deeper waveguide for the HiVi isodynamic RT2C (similar to the RT2H-A) could help support an "acceptable" 1.6-1.7kHz crossover frequency to the 8". This would generate a smoother directivity pattern, and reduced lobing. Plus create a closer physical time delay.
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Thanks for the input guys.
I had intended these for nearfield on-axis listening duties at my drafting table.
I thought about a three way but since I'll probably use my MiniDSP I thought I would give it a try first and see what sort of on-axis response I could wring out of these.
(Aside from the added complexity and cost of a three way)
I have a pair of Fostex studio monitors (RM865) which are 8" co-axial drivers with circular planar tweeters crossed way up high; and I love their sound, which is why I thought I could get away with this combo.....
But of course I am always open to the good suggestions of those wiser than I.....🙂
I had intended these for nearfield on-axis listening duties at my drafting table.
I thought about a three way but since I'll probably use my MiniDSP I thought I would give it a try first and see what sort of on-axis response I could wring out of these.
(Aside from the added complexity and cost of a three way)
I have a pair of Fostex studio monitors (RM865) which are 8" co-axial drivers with circular planar tweeters crossed way up high; and I love their sound, which is why I thought I could get away with this combo.....
But of course I am always open to the good suggestions of those wiser than I.....🙂
1- the 8" will be lucky to not beam that high. 8" are really only good to about 1.5-2k before beaming.
2- An HiVi RT2C is a round faceplate. They are good to approximately 2.3k at the lowest.
3- What you have, do they say Silver Flute, Dayton Audio, yindi, or Dayton Loudspeaker on the back? I'm betting you have Dayton Audio PT2-B or PT2-C. If you have a PT2C, your response graph you posted is not how they measure.
Isodynamic Ribbon Tweeters Drivers_HiVi,Inc.
Later,
Wolf
2- An HiVi RT2C is a round faceplate. They are good to approximately 2.3k at the lowest.
3- What you have, do they say Silver Flute, Dayton Audio, yindi, or Dayton Loudspeaker on the back? I'm betting you have Dayton Audio PT2-B or PT2-C. If you have a PT2C, your response graph you posted is not how they measure.
Isodynamic Ribbon Tweeters Drivers_HiVi,Inc.
Later,
Wolf
I bought the tweeters from another member, the pics are in my first post.
They are the ones with the square faceplate, I believe Daytons.....
They are the ones with the square faceplate, I believe Daytons.....
I've tried this configuration (8" light paper cone midbass and a supertweeter) the sweet spot is so tiny (vertical and horizontal) that i've used very precise postural measurement in order to listen the mids, each time you turn your head slighly to look a one loudspeaker, you loose the mids.
It is a fun idea, but you should buy a goniometer if you need to listen the mids.
this
get the rt2h, xo at 1250 hz
and get a higher eff 8 inch woofer to match better with the rt2h sensitivity
The RT2H cannot xover that low. 2.3k is about the limit of those units. 2k they sound stressed.
OP- then you have PT2C instead of RT2C- VERY different units. The FR plot you posted is for the RT2C, and is wrong for the PT2C. The PT2C (I've used them) is only good down to 2.3k (24dB) at the lowest, and 2.1k in multiples, 3k (12dB) for better usage.
This is the FR of the PT2:
https://www.parts-express.com/pedocs/specs/275-085--dayton-audio-pt2c-8-specifications.pdf
It has a peak before lowend rolloff, and a peak before highend rolloff, and a broad dip in the middle.
Later,
Wolf
OP- then you have PT2C instead of RT2C- VERY different units. The FR plot you posted is for the RT2C, and is wrong for the PT2C. The PT2C (I've used them) is only good down to 2.3k (24dB) at the lowest, and 2.1k in multiples, 3k (12dB) for better usage.
This is the FR of the PT2:
https://www.parts-express.com/pedocs/specs/275-085--dayton-audio-pt2c-8-specifications.pdf
It has a peak before lowend rolloff, and a peak before highend rolloff, and a broad dip in the middle.
Later,
Wolf
When listening in the nearfield, you want tight spacing between the woofer and the tweeter. Basically the bigger the gap is, the further away you need to listen.
Nothing wrong with a nice 8" based two way....
- Techtalk Speaker Building, Audio, Video Discussion Forum
Keep on truckin McTavish!
- Techtalk Speaker Building, Audio, Video Discussion Forum
Keep on truckin McTavish!
Also, personally, I would do all my measurements at the listening location. Attempting to do quasi-anechoic, and then compensating for baffle-step, etc. is to me more fraught with peril. Since these will be very specific use speakers, and you'll be crossing over high, I think the rest can be avoided.
Depending on your wall placement, etc. you may even avoid an efficiency robbing bsc circuit altogether.
Best,
E
Depending on your wall placement, etc. you may even avoid an efficiency robbing bsc circuit altogether.
Best,
E
Thanks for all the input guys...
But......
Looks like there is a change of plan. The tweeters arrived and they are CRAP!!!!🙁
The membranes are slack and appear to have been overheated and the neodymium magnets have literally disintegrated..... Not only is the coating wearing off, but the actual body of the magnet itself is turning to powder.😡
A waste of time and money.
The goals stay the same, a bookshelf with the SB woofer. Now I just need a replacement for the highs. Either a nice tweeter or I had thought about a ScanSpeak 10F and crossing around 3-400hz.
But......
Looks like there is a change of plan. The tweeters arrived and they are CRAP!!!!🙁
The membranes are slack and appear to have been overheated and the neodymium magnets have literally disintegrated..... Not only is the coating wearing off, but the actual body of the magnet itself is turning to powder.😡
A waste of time and money.
The goals stay the same, a bookshelf with the SB woofer. Now I just need a replacement for the highs. Either a nice tweeter or I had thought about a ScanSpeak 10F and crossing around 3-400hz.
Just ordered these Peerless : XT25TG30-04, should pair well with the SB's.....
Shame bout the HiVi's though, I was really excited to give some isodynamics a try....🙁
Shame bout the HiVi's though, I was really excited to give some isodynamics a try....🙁
I have many very pricey good texile dome tweeters, and one pair of "cheap challenge" DIY loudspakers with a Visaton BG16 (15$ 6" fullrange) with a cheap monacor RBT95, i'm blowed by the quality of the treble each time i listen to them.