House Jam Micro Combo

[JohnDaBass]

The Backstory

 

Once or twice a month during the long winter several friends and acquaintances gather in the bar of a village pub to enjoy a jam and general sing-along. With ages ranging between late 60s and 70s the music is very broad and covers, 60s/70s pop, Delta Blues, traditional Blues, soft rock, Celtic folk and of course always end with Sir Tom’s Delilah. Simple rules No amps No Mics just acoustic guitars & instruments, generally there’s 3 or 4 guitars, mandolin, Bodhrán and vocals. My Fender Kingman is a great bass with 34 ins scale Jazz neck and huge body which resonates quite well, BUT just gets lost amongst the other instruments.

So, I have been pondering for a while for some form of non-intrusive sound reinforcement, something small that could be tucked away under a table and linked wirelessly to the Kingman.

 

The Concept

 

I have followed with interest the posts on the Warwick Gnome, Trace Elf and @Phil Starr House Jam Micro cab, and decided to build a micro combo.

I purchased the TC BAM200 as the internal DFM (design for manufacture) really appealed to me with no cable harnesses and an elegant single PCB layout. BTW it was also the cheapest at the time!!

 

 

I chose a Faital RS140 speaker mainly as it had a 200w rating and the specs suggested that it had a reasonable low end.

To create a combo from Phil’s cab design I could have added a simple slot above the cab but being so physically small access to the controls would have been inconvenient. So I decided to clone the popular combo approach by adding a recess to the back of the cab and having the controls pointing upwards. There was a bit of head scratching to shuffle around each of the elements changing Phil’s square cubbish cab to a taller bi-dimensional cab layout.

 

 

The Build

 

Following Phil’s tried and tested method I used 12mm Ply and 12 x 15mm battens but used my pneumatic nail gun with 15mm & 30mm brads.

 

 

There was a fair amount of extra routering to form the access to the amps controls.

 

 

Because of bi-dimensional rear there seemed little need for additional bracing but I did add a brace between the back and the baffle. 

 

 

Tuff Cab rules, several coats with brush and roller, and the cab was lined with the fibre wadding.

 

 

The amp was held in with 10mm x 2 mm aluminium bar lined with speaker mounting rubber tape. 

The amp fixing bar is held with 2 x 5mm Allen bolts so is easily removed if I need to use the amp as a backup for my other rigs.

 

 

I added slots in the cab walls on the RHS to provide some ventilation and also had to drill a few holes in the Aluminium bar to avoid covering some of the vent holes on the amps side.

 

 

The Faital RS140 is a fine piece of engineering with RMS rating of 200w, even though the BAM200 only outputs around a 100w at 8 ohms I wanted sufficient speaker head room just in case I added an extra 8 ohm cab in the future.

 

 

I hit a few tuning issues but with the help of @Phil Starr I replaced the 70mm port with a single 38mm port. In the end I added a second 38mm port to reduce the "chuffing" and improve the low end performance. ( Can anyone spot the deliberate mistake!!) 

 

 

I had some Fender style speaker cloth and a Fender logo in the basement so used both to finish the job.

Fender Micro CHAMP , CHIMP  IMP Combo 

 

 

The amp recess at the rear turned out well and with the aid of @Chienmortbb superb speaker cable the combo looks reasonably presentable. 

 

 

 

I still may do some further faffing around with ports and cab tuning but with my Lekato 5.2Ghz wireless system I can hide the combo under a table in the bar and no one will ever know I'm breaking the acoustic only rules!!!

 

I plan for the Micro combo to live in the lounge tucked away by the side of the TV so with a bass plugged into my Zoom B1 Four sat on the sofa and out with the Lekato to the combo I don't have any leads trailing across the lounge floor and I can play-along with YouTube and DVDs at a sensible level.

Happy Days!!

 

 

 

[Woodwind]

1 hour ago, JohnDaBass said:

The Backstory

 

Once or twice a month during the long winter several friends and acquaintances gather in the bar of a village pub to enjoy a jam and general sing-along. With ages ranging between late 60s and 70s the music is very broad and covers, 60s/70s pop, Delta Blues, traditional Blues, soft rock, Celtic folk and of course always end with Sir Tom’s Delilah. Simple rules No amps No Mics just acoustic guitars & instruments, generally there’s 3 or 4 guitars, mandolin, Bodhrán and vocals. My Fender Kingman is a great bass with 34 ins scale Jazz neck and huge body which resonates quite well, BUT just gets lost amongst the other instruments.

So, I have been pondering for a while for some form of non-intrusive sound reinforcement, something small that could be tucked away under a table and linked wirelessly to the Kingman.

 

The Concept

 

I have followed with interest the posts on the Warwick Gnome, Trace Elf and @Phil Starr House Jam Micro cab, and decided to build a micro combo.

I purchased the TC BAM200 as the internal DFM (design for manufacture) really appealed to me with no cable harnesses and an elegant single PCB layout. BTW it was also the cheapest at the time!!

 

 

I chose a Faital RS140 speaker mainly as it had a 200w rating and the specs suggested that it had a reasonable low end.

To create a combo from Phil’s cab design I could have added a simple slot above the cab but being so physically small access to the controls would have been inconvenient. So I decided to clone the popular combo approach by adding a recess to the back of the cab and having the controls pointing upwards. There was a bit of head scratching to shuffle around each of the elements changing Phil’s square cubbish cab to a taller bi-dimensional cab layout.

 

 

The Build

 

Following Phil’s tried and tested method I used 12mm Ply and 12 x 15mm battens but used my pneumatic nail gun with 15mm & 30mm brads.

 

 

There was a fair amount of extra routering to form the access to the amps controls.

 

 

Because of bi-dimensional rear there seemed little need for additional bracing but I did add a brace between the back and the baffle. 

 

 

Tuff Cab rules, several coats with brush and roller, and the cab was lined with the fibre wadding.

 

 

The amp was held in with 10mm x 2 mm aluminium bar lined with speaker mounting rubber tape. 

The amp fixing bar is held with 2 x 5mm Allen bolts so is easily removed if I need to use the amp as a backup for my other rigs.

 

 

I added slots in the cab walls on the RHS to provide some ventilation and also had to drill a few holes in the Aluminium bar to avoid covering some of the vent holes on the amps side.

 

 

The Faital RS140 is a fine piece of engineering with RMS rating of 200w, even though the BAM200 only outputs around a 100w at 8 ohms I wanted sufficient speaker head room just in case I added an extra 8 ohm cab in the future.

 

 

I hit a few tuning issues but with the help of @Phil Starr I replaced the 70mm port with a single 38mm port. In the end I added a second 38mm port to reduce the "chuffing" and improve the low end performance. ( Can anyone spot the deliberate mistake!!) 

 

 

I had some Fender style speaker cloth and a Fender logo in the basement so used both to finish the job.

Fender Micro CHAMP , CHIMP  IMP Combo 

 

 

The amp recess at the rear turned out well and with the aid of @Chienmortbb superb speaker cable the combo looks reasonably presentable. 

 

 

 

I still may do some further faffing around with ports and cab tuning but with my Lekato 5.2Ghz wireless system I can hide the combo under a table in the bar and no one will ever know I'm breaking the acoustic only rules!!!

 

I plan for the Micro combo to live in the lounge tucked away by the side of the TV so with a bass plugged into my Zoom B1 Four sat on the sofa and out with the Lekato to the combo I don't have any leads trailing across the lounge floor and I can play-along with YouTube and DVDs at a sensible level.

Happy Days!!

 

 

 

 

This is absolutely superb!!

 

May I ask some obligatory annoying questions?

 

How much did the Faital speaker cost?

Would it be possible to have a playing video to gauge sound levels?

 

Once again, absolutely superb work and a real inspiration, thank you

[JohnDaBass]

Thank you for your kind words.

 

I purchased the Faital RS140 from Blue Arran it was one of the last in stock, I was told that the shipment due in March would suffer a price increase. It cost me £77. But take a good look at the Fane 6-100 that Phil used it's a bit heavier but has a fantastic performance.  I chose the Faital because of its higher power rating.

 Not sure I'm sufficently competent enough to post a video,  but listen to Phil Starr's live video on the House Jam Micro Cab thread, it will surely surprise you. 

[Woodwind]

13 minutes ago, JohnDaBass said:

Thank you for your kind words.

 

I purchased the Faital RS140 from Blue Arran it was one of the last in stock, I was told that the shipment due in March would suffer a price increase. It cost me £77. But take a good look at the Fane 6-100 that Phil used it's a bit heavier but has a fantastic performance.  I chose the Faital because of its higher power rating.

 Not sure I'm sufficently competent enough to post a video,  but listen to Phil Starr's live video on the House Jam Micro Cab thread, it will surely surprise you. 

 Ah I wondered of you'd got one of the last ones. Like you I was looking for something that could take a bit more power if the situation called.

[Phil Starr]

Well done John, this is what self build should be about. I love it when someone takes a design and with a bit of initiative  pushes it a little further.

 

The original House Jam speaker was built just for this use and started life using a guitar practice amp to drive the speaker. All I wanted was something with just enough power to match an acoustic guitar for those 'acoustic only' occasions. It was only when I tried the cab only version with my proper bass amp that I realised it could be pushed a lot further than that.

 

So now I'm going to have to do some work building my own combo. I bought a Warwick Gnome (I wanted the BAM but it wasn't available at the time) to do just that but haven't pulled my finger out yet.

 

I hope you get many hours of pleasure from your design, I hope the acoustic world is ready for you

 

 

Edited January 12, 2022 by Phil Starr

[JohnDaBass]

UPDATE

Over the weekend  I finally got around to improving the port arrangement of the Micro combo.

I had some great help and advice from @Phil Starr regarding the size of the Port. I changed the original port to 2 ports 38mm id x 100mm long but sadly I was experiencing some nasty "chuffing".

On Phil's advice, over the weekend I replaced the two ports with one port 70mm id X 96mm long and the performance has improved considerably.

My implementation of the cab & speaker is still not as good as the solution Phil adopted and this can be seen in the curves below. 

 

Phil's is the GREEN curve (85Hz), the two 38mm id x 100mm ports is the BLUE and the 70mm id x 96 mm is in RED (85Hz).

The Fane does appear to perform very well in a small cab and maybe if I had spent more time in the research and calculation phase rather than jumping too quickly into the construction phase I may have achieved a better performance out of the Faital.

Any how, I am pleased with the improvement in performance and happy that the chuffing has disappeared.

Thanks again to @Phil Starr for his excellent support.

Edited April 18, 2022 by JohnDaBass
details added

[Richard R]

The $64,000 question of course, have you used it at the intended sessions, and were you rumbled?

[JohnDaBass]

1 minute ago, Richard R said:

The $64,000 question of course, have you used it at the intended sessions, and were you rumbled?

Yes, used it at a small acoustic jam ( 3 acoustic guitars & 4 vox) before the change of port arrangement and the guys were quite comfortable with it hidden away. I was really impressed with the extra sound reinforcement that enabled me to enjoy a much more relaxed experience. Rather than belting hell ( digging in) out of the strings to get heard and cut through I was able to play at normal house levels and benefit from the reinforcement the micro combo delivered. I have to say that the Lekato 5.2Ghz wireless system works very well indeed. Next week I am sure that I will be even more comfortable with the improvement in performance and removal of the chuffing.

[Richard R]

Excellent result all round. I like the sound of acoustic basses, but they simply aren't loud enough to sit with guitars. Your idea of wireless and a tiny amp is brilliant.

 

 

[Chienmortbb]

Well done John and I am sure the lessons learnt are almost as satisfying as the combo itself. Many don't realise that the acoustic basses by Washburn were only produced to be used at MTV's unplugged series and of course they were amplified at the sessions by the FOH system, In my opinion they are almost useless without amplification and it does not have to be "in yer face". Just a little push makes all the difference. Well done.