Monacor SP-310CX build

A place for DIY project discussions.
User avatar
Docfoster
Posts: 231
Joined: Tue Jun 18, 2019 11:06 am
Has thanked: 33 times
Been thanked: 129 times
Contact:
Wales

Re: Monacor SP-310CX build

Unread post by Docfoster »

Had a very messy day yesterday.
Painted the insides of the cabinets with bitumen paint.
What a lovely substance to work with that is.

The process was made worse when I knocked one of the still-attached-to-the-crossover drivers off the work bench and it ripped out most of the crossover components. And unravelled one of the inductors. Ugh.
What a clumsy oaf I am.

Fortunately I had a spare inductor.
And the time to reconstruct the crossover.

3 coats of bitumen in both cabs (about a third of a litre per speaker).

Sounds dead good. Any cabinet-induced sound reduced a few notches. Perhaps most noticeable in mid-range. Things are more detailed and smoother.

I'm aware that Doc-modding encourages steel plates to be glued to inside of cabs. To reduce cabinet resonance I think...? I've never tried that. The bitumen thing aims to achieve something similar.

If anyone wants to try this, I would strongly recommend doing so when constructing the cabinet. Doing it retrospectively was horrific.
Also, I'm aware that each of the cabinets is now about 1% smaller in volume. Probably not hugely significant, but in future I would allow for 2mm of bitumen paint on all inside surfaces. If done during construction, I'd simply pour the bitumen paint to the required depth on to each inner surface, in turn.
System 1: JRiver MC24 > Dell Latitude 7270 > Asus Xonar Essence One Muses Edition DAC & pre- > One4 Class A power amp (with Dynamic PSU boards) > DIY Monacor SP-310CX speakers & DIY Dayton Audio SD315A-88 bass cab.
LC Audio Technology mains DC filter > Sovereign MTBPS balanced power supply
TQ (Wonfor) Ultra Black cables.

System 2: Anything with a headphone socket > Inca Tech Claymore > DIY Monacor SP-308CX speakers

Daniel Quinn
Posts: 8586
Joined: Thu Jul 12, 2012 7:16 am
Has thanked: 24 times
Been thanked: 399 times

Re: Monacor SP-310CX build

Unread post by Daniel Quinn »

Bitumin will attenuate in the audio band. This could be good or bad.

Daniel Quinn
Posts: 8586
Joined: Thu Jul 12, 2012 7:16 am
Has thanked: 24 times
Been thanked: 399 times

Re: Monacor SP-310CX build

Unread post by Daniel Quinn »

Bitumin will attenuate in the audio band. This could be good or bad.

Also, I would have used bitumin pads :grin:
These users thanked the author Daniel Quinn for the post:
Geoff.R.G (Sun Aug 09, 2020 12:26 pm)

User avatar
Docfoster
Posts: 231
Joined: Tue Jun 18, 2019 11:06 am
Has thanked: 33 times
Been thanked: 129 times
Contact:
Wales

Re: Monacor SP-310CX build

Unread post by Docfoster »

Daniel Quinn wrote: Mon Aug 03, 2020 2:16 pm Also, I would have used bitumin pads :grin:
Work-shy lightweight.
System 1: JRiver MC24 > Dell Latitude 7270 > Asus Xonar Essence One Muses Edition DAC & pre- > One4 Class A power amp (with Dynamic PSU boards) > DIY Monacor SP-310CX speakers & DIY Dayton Audio SD315A-88 bass cab.
LC Audio Technology mains DC filter > Sovereign MTBPS balanced power supply
TQ (Wonfor) Ultra Black cables.

System 2: Anything with a headphone socket > Inca Tech Claymore > DIY Monacor SP-308CX speakers

User avatar
Docfoster
Posts: 231
Joined: Tue Jun 18, 2019 11:06 am
Has thanked: 33 times
Been thanked: 129 times
Contact:
Wales

Re: Monacor SP-310CX build

Unread post by Docfoster »

I think they're finished now.

I'm not really happy with the final look. For future projects I need to do more research and work on coverings and edgings.
But sound-wise, I am very happy. Happiest I've been with my system.
Time and effort spent fine-tuning things is a good investment.

Image

Main learning points for me from this project...
Bitumen can be a good internal damping material.
In my room, fixing speakers to concrete slabs is helpful.
These particular drivers sound better with the crossover frequencies overlapped (700Hz - 1000Hz).

Back of fag packet costings (including stands) is £540...

2x Monacor SP-310CX Drivers £250
25mm MDF (cut by merchant) £25
Screws and fixings £10
Bitumen £10
Acoustic foam £20
Crossover components £80
Cabling and binding posts £25
Coverings £40
Monacor badges £15
Stands (MDF and hard wood dowel (cut my merchant)) for £80

At the start of the project my long-term plan was to have these as two-thirds of a big speaker stack, sitting atop of a bass cab handling <75Hz. But... I am sufficiently pleased with the bass repsonse from the Monacor SP310CX drivers that I currently have insufficient motivation to proceed with that. May be a project for next year / next lockdown.

Image
These users thanked the author Docfoster for the post (total 3):
savvypaul (Sat Aug 08, 2020 10:54 am) • SteveTheShadow (Sat Aug 08, 2020 11:45 am) • karatestu (Sat Aug 08, 2020 12:41 pm)
System 1: JRiver MC24 > Dell Latitude 7270 > Asus Xonar Essence One Muses Edition DAC & pre- > One4 Class A power amp (with Dynamic PSU boards) > DIY Monacor SP-310CX speakers & DIY Dayton Audio SD315A-88 bass cab.
LC Audio Technology mains DC filter > Sovereign MTBPS balanced power supply
TQ (Wonfor) Ultra Black cables.

System 2: Anything with a headphone socket > Inca Tech Claymore > DIY Monacor SP-308CX speakers

User avatar
karatestu
Posts: 5945
Joined: Sun Jan 08, 2017 4:40 pm
Location: North Yorkshire
Has thanked: 1865 times
Been thanked: 1378 times
Great Britain

Re: Monacor SP-310CX build

Unread post by karatestu »

Good work Doc :clap:

I am interested to know why you went for that shape box ?
DIY FREE ZONE

User avatar
Docfoster
Posts: 231
Joined: Tue Jun 18, 2019 11:06 am
Has thanked: 33 times
Been thanked: 129 times
Contact:
Wales

Re: Monacor SP-310CX build

Unread post by Docfoster »

karatestu wrote: Sat Aug 08, 2020 12:45 pm Good work Doc :clap:

I am interested to know why you went for that shape box ?
It's just a cuboid. Its proportions are a bit distorted by the camera lens in that last photo.
The proportions were determined by my wanting it to sit on top of my old speakers, and wanting it to be as low as possible.
System 1: JRiver MC24 > Dell Latitude 7270 > Asus Xonar Essence One Muses Edition DAC & pre- > One4 Class A power amp (with Dynamic PSU boards) > DIY Monacor SP-310CX speakers & DIY Dayton Audio SD315A-88 bass cab.
LC Audio Technology mains DC filter > Sovereign MTBPS balanced power supply
TQ (Wonfor) Ultra Black cables.

System 2: Anything with a headphone socket > Inca Tech Claymore > DIY Monacor SP-308CX speakers

User avatar
karatestu
Posts: 5945
Joined: Sun Jan 08, 2017 4:40 pm
Location: North Yorkshire
Has thanked: 1865 times
Been thanked: 1378 times
Great Britain

Re: Monacor SP-310CX build

Unread post by karatestu »

Makes perfect sense. I never used to pay much attention to box shape. Winisd gives you suggested dimensions when designing a box. I think they use the golden ratio.

A cube is said by many to be one of the worst shapes for a speaker enclosure but I think RD was on to something with the cube design.

I hope you enjoy them :guiness;
DIY FREE ZONE

Geoff.R.G
Posts: 1562
Joined: Thu Aug 11, 2016 2:46 pm
Location: Denham UK
Has thanked: 132 times
Been thanked: 476 times
Great Britain

Re: Monacor SP-310CX build

Unread post by Geoff.R.G »

karatestu wrote: Sat Aug 08, 2020 3:32 pm Makes perfect sense. I never used to pay much attention to box shape. Winisd gives you suggested dimensions when designing a box. I think they use the golden ratio.

A cube is said by many to be one of the worst shapes for a speaker enclosure but I think RD was on to something with the cube design.

I hope you enjoy them :guiness;
I think the cube is frowned upon because of "standing waves" but, as I have pointed out before, standing waves require constant excitation and music just doesn't do that. There are some sounds that can excite a standing wave but careful cabinet design can eliminate them. Basically design a cabinet that doesn't support a standing wave at a common problem frequency.

User avatar
TheMadMick
Posts: 437
Joined: Tue Jan 31, 2017 9:50 am
Location: SOUTHPORT, UK
Has thanked: 3 times
Been thanked: 141 times
ST_PATRICK'S_SALTIRE

Re: Monacor SP-310CX build

Unread post by TheMadMick »

Wasn't it Bosnedorfer, the Austrian piano maker, who designed speakers to deliberately vibrate like a piano? I seem to remember they were very tall with a curved back that ended in a slot all the way down one side. Of course, they were immaculately finished and very expensive!
Blusound Vault 2, P50SA, A80's, BMU, TIS, LS7, MA PL200, Meridian 506 (18 bit).

Post Reply