Budget Audiophile Build

We love good audio and had lived off the sounds from tiny portable blue tooth speakers for years while travelling. The challenge, create a wide sound stage sound system that approached audiophile standards – without paying the thousands of $$ to get the valve based system and speakers that could produce the sound we wanted. Research, patience, an incredibly steep learning curve, and we designed and built a system that very nicely produced sound from 20hz - 20khz (bass you feel to highs you hear) across all volumes. Any volume audiophile success – its the clean wide sound that we like without having to crank excessive volume to achieve it.

The valve pre amp started off as a NZ$30 temu special NFJ&FX 03 valve pre amp. I upgraded the power supply from 12vDC to 24vDC @ 5amps. Removed the 6J1P valves and replaced with genuine 1952 JAN-GE 5654w tubes – military grade valves. I also did minor surgery and removed the NE5532 op amps and replaced them with Muses01. Its fed from a NZ$3.75 Temu DAC and feeds into the main speakers amp.

The sub amp started life as a TPA3116 board and after similar upgrades as I did with the pre amp I ended up with a compact custom amp with a selectable frequency response from 20 - 180 hz and gain control. It runs at about 80 hz roll off and 45% gain from a line out source off the main speakers amp. It feeds into a 10" Ripole sub driver.

Our TV has an optical out to the DAC, into the pre amp and from there into the main amp. The main amp feeds into the speaker and a line out to the sub amp which in turn feeds the 10" Ripole sub. The main amplifier is a trade me bargain. A Unity 100w 240v brigable amp originally designed more for PA system use, running @ 4ohm x 2 65w channels. It also has a triggered power on option thats nice to have as the unit is hidden in a cupboard, and line out that feeds the sub amp.

Originally these were a dirt cheap trade me purchase of a set of barely used 25 year old Acclaim SA3000F 120w 6ohm floor speakers. They had a 2 way arrangement with 2 x 6.5" drivers and a domed tweeter with a claimed 87db frequency response from 30hz - 20khz. Could find very little about them on the internet aside from they were originally a co=production between B&W and Acclaim attempting to break into the then newish home theatre system mid range market. In the absence of any detailed Thiele/Small (T/S) parameters on the 6.5" drivers I used a best guess average on design to get a minimum chamber size and adequate porting (and packed the chamber with fibre glass wool). The tweeters are in their own cabinet mounted on top again with a minimum chamber size. Luckily I'm happy with the result. The cabinet is made from baffled 18mm particle board with 10mm ply covering that. The tweeter chambers 10mm ply glued and screwed layers shaped into their cones. There are many cabinet design calculators online FYI.

Again another bargain trade me find. A Polk Audio DB10 sub driver, boxed and a spare from a 1990's Polk Audio Signature Range Theatre system (good luck on internet searches, but forums say the system was the shit of theatre systems). The original system has 35 active drivers and cost a fortune. I was also able to find the Thiele / small specs for the DB10 driver via an obscure online forum. Total nerd stuff and a massive learning curve. Ripole subs are designed and intended to give non-localised bass without the whump whump of many cheap systems around today, but still give bass you can feel. Originally invented by Ridtahler Dipole and patented in 2000, a Ripole is (copied)"a compact subwoofer design with opposing woofers in a folded, baffle-less cabinet that creates a cardioid radiation pattern, reducing room booming by exciting fewer room modes and allowing for deep bass from a small enclosure by lowering the driver's resonant frequency". My design is a modified single driver Ripole. You need the drivers Xmax and a few other measurements to design the cabinet.

SD of the driver π x (D/2) x 2 where D = cone diametrer + 1/2 width ring either side. The front chamber port needs to be 1/3 to 1/4 of the combined piston area. If the Xmax is <10mm then 1/4. If  >10mm then 1/3. The rear chamber port needs to be 1/2 - 1 times the SD of the driver. The rear chamber depth enough to house the driver. Good luck – if you want to build get online and research, and apologies if my brief description of the calculations is incorrect here. Been a while and notes are a little interesting to read now.

I used 18mm ply with double baffles / thickness where the driver mounts. For a dual driver build you simply dont add a fron cover and place the two cabinets so the drivers are facing into each other. The individucal cabinet specs don't change.

Catalogue Number: 0002

Date of completion: October 2025