Group Buys — MAC/DIY

Bevenbi Capacitor Group Buy - Interest assessment thread

a4eaudio — Wed, 29 Jan 2025 01:45:15 +0000

There was mention in a different thread about Bevenbi capacitors (which I had never heard of). They appear to be used in B&W speakers and have a good reputation from what I could fine. Of interest would be the Silver Series which are priced a little more than Clarity Cap, about twice that of Jantzen Standard Z-Cap, and a decent amount less than Audyn Plus.

First question is, who would be interested in a Group Buy? I would interpret "interested" as more than 50% likely you would participate if the selection was suitable for you.
Second question, what values would be a good standard set to buy?
Third question, 250V or 400V?

Below is a table of some of the information I have gathered.

Prices are a little better on Aliexpress than eBay. However, Aliexpress only offers the 240V version, and only the values in light blue. The values in dark blue (those less than 1.0uF) are available on eBay. 400V are available on eBay only (at least I didn't find them on Ali), 0.10uF up to 12uF.

I selected some standard values and priced what a pair of each value would cost (this does not include shipping, tax, tariffs, etc.) Prices in the blue and green columns are a quick estimate, prices for a pair of each highlighted yellow and orange are at the bottom of the table. This is just to illustrate a possibility, I look forward to suggestion on what values people would prefer. The ones without a price are available, I just didn't want to spend too much time fully populating the table.

Just to be clear - a pair of 240V caps in each 1.5uF, 2.2uF, 2.7uF, 3.3uF, 3.9uF, 4.7uF, 5.6uF, 6.8uF, and 8.2uF caps would be about $200, so we aren't talking Dayton Audio or Audyn Q4 prices! If there is enough interest, I don't mind organizing, even though I may be too frugal to pull the trigger myself.

Any interest in a group buy for Airborne AMT?

rjj45 — Wed, 07 Mar 2018 12:09:23 +0000

There's a guy at DiyAudio who has completed one group by of Airborne AMT tweeters, and is preparing to do another one.
Prices are pretty excellent. Probably take a few months for delivery from CN.
Details are here:
http://www.diyaudio.com/forums/planars-and-exotics/312560-looking-hygeia-airborne-amt-tweeters-designs.html

I'm going to order Aurum Cantus AMT diaphragms, anyone need any?

OscarJr — Thu, 03 Oct 2019 13:59:06 +0000

Parts Express doesn't carry these items (I emailed P.E. to check), so I don't believe this post goes against any rules.

I am going to order diaphragms for my AST 25120's and 30130's. If anyone needs these diaphragms, here is the pricing they gave me:

Item	Cost
AST 30130 replacement diaphragm	60
AST 25120 Replacement Diaphragm	75

The shipping charge seems reasonable @ $59, and my wire transfer fee is about the same (both of those additional charges would be split up). Individual shipping I could use USPS P.M., which is extra.

Let's talk 16 ohm midwoofer possibilities...

jr@mac — Fri, 19 Jan 2018 16:06:59 +0000

All,

What would you look for in a 16 ohm woofer? Cost? Maximum extension? Minimal cabinet size? Ability to play high? Let's drop some thoughts here!

Personally, I like the look of a three woofered system - but I understand a lot of people may not have an amplifier capable of running three 12 ohm woofers, hence the 16 ohm option.

To me, and your mileage may vary, I am looking for:

1. Cost. On a system using six woofers, costs can escalate. This is not to say I am looking for GRS level costing, but I am also unable to commit to a sextet of $200 woofers, either.

2. Reasonably small enclosure requirements. When we are talking 3x the cabinet volume, it becomes an issue if the driver likes a cubic foot or more for maximum performance.

3. Decent extension - say it models well in a smallish enclosure to 40Hz.

4. I am not personally looking at sensitivity - as we will expect a significant boost through three paralleled drivers. A lower sensitivity option will not be a deal breaker to me.

5. Solid Xmax - see above points.

Thoughts? Throw them out, lets discuss!

Sending out a feeler...

jr@mac — Tue, 23 Aug 2016 17:23:26 +0000

OK, did some thinking and... I love the look of three woofer towers. Sadly, with mainstream driver selection that means we need big swinging dingus king kong super arc welder amps to power them. I am fairly certain my Theta will drive a nominal ~2.7 ohm design - but most bread and butter amps will take a shit when asked to power through that.

So, that being said - does anyone have any interest in a group buy for 16 ohm woofers? I have done some legwork previously on MoQ for Dayton Audio in the past, and I imagine most suppliers will have similar requirements. For sake of argument, let's assume Qty 100 is the point at which we can expect to have drivers with custom coil windings etc. However, each vendor is probably going to impose different requirements and limitations.

Here are some of the drivers I think would be great in a 16 ohm version:

1. Eclipse W6520R
2. Dayton DC160
3. Dayton DA215
4. MCM 55-2669
5. Tang Band W6-1139SIF

Those are just five drivers that popped into mind, and I'll explain my selection process a bit.

The Eclipse is really close to being a world-class driver at a seriously competitive price point. I found it to have a very satisfying bass tonality and it works well in a 2-way as well as a 3-way. It is, as evidenced by several DIY event incidents, displacement limited in a single driver mode and currently there are no options other than the 4 ohm model making a dual woofer setup kind of moot if the builder does not possess a high current amp to drive past the 8 ohm impedance.

The DC160 is also severely output limited due to limited Xmax, but offers really good extension in a small footprint and a nice price point.

The DA215 is an 8" woofer that, while not playing particularly low, will work nice in a smallish cabinet

The MCM 55-2669 is a beast of a 5-1/4" and I was unable to make it sound ugly during excursion testing - in fact, the surround was probably the limiting factor. It is also very clean through the lower midrange, and the anodizing on the cone is a beautiful, nearly pearlescent appearance.

The Tang Band, well who wouldn't want a triple driver tower with these as the anchor? Holy crap.

I will be willing to take point on this project if we can drum up enough interest. If MoQ is 100, that would be 17 guys committing to six drivers each, or 13 guys committing to eight drivers each. I think that is a reasonable expectation.

Of course, I am open to other driver options, as well.

Concentric driver

jr@mac — Mon, 12 Jun 2017 22:32:13 +0000

At DDIY this year, Brad brought a pair of speakers using a 4" concentric T/M module. I briefly discussed the possibility of a group buy - who is interested?

New Viawave tweeters...

jr@mac — Mon, 12 Jun 2017 22:29:51 +0000

...are in production. Roman may be able to work a discount if interest is high enough. Please post your interest in, and probability of committing to, a group buy in this thread. I will coordinate with Roman if need be.

Digikey - Tymphany dealer...

jr@mac — Sun, 23 Apr 2017 13:09:36 +0000

Thought I would start a thread independent of JP's current build thread to discuss some cool drivers available at Digikey. One of them that caught my eye was this:

https://www.digikey.com/product-detail/en/0/SBS-200F35CP01-04-ND/6557504?quantity=10&cref=&em1=Minumum Quantity Not Met&uq=636285307729415898

9.1mm Xmax and a $22 price point - but MOQ is 500 pieces and not sure I want to drop 10K to test a driver lol!

There are 6.5" and 10" versions, too. Matching passives, to boot. These look like great drivers for tinkering with DSP.

SOooo.... if someone (maybe me) were to, say, reach out to Digikey and talk to them about a smaller MOQ, would anyone be interested in pursuing some of the Tymphany drivers they offer? There are a lot of really cool drivers that Tymphany has been developing and releasing - but are not available through traditional outlets such as Mad/Men/Pe/MCM. Want to talk about a cool Iron Driver option...

Digikey is kind enough to provide a "download table" option when you apply filters, see attachment. It is all (I think) of the drivers from Tymphany that Digikey has listed.

Let me know!