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Chienmortbb

After Eighty - Small Ashdown Combo On Steroids

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On 13/06/2020 at 09:32, nilebodgers said:

A common technique is to use back-to-back 12V zeners with a resistor in the 1k - 3k3 range (plus a 50V min blocking capacitor). GK do that on a lot of their later models.

 I looked at that and it makes sense. More parts to order....

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I tried the fan today and as mentioned earlier it was electrically noisy.  So three options, eihter a dedicated regulator for the fan, OR a 230V fan or suck it and see. I have chosen option 3 fior the time being with some small tweeks for the convection cooling. Next up is to wire in the Bright switch and the power LED. I need to order a switch for the Mute Switch.

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1 hour ago, Chienmortbb said:

I tried the fan today and as mentioned earlier it was electrically noisy.  So three options, eihter a dedicated regulator for the fan, OR a 230V fan or suck it and see. I have chosen option 3 fior the time being with some small tweeks for the convection cooling. Next up is to wire in the Bright switch and the power LED. I need to order a switch for the Mute Switch.

You could pinch the thermostatic fan control circuit from something like the GK MB200 that uses the same ICE module.

See:

924121763_mb200fancontrolsch.thumb.png.d1e16089ac191b490fedcd4ff1a0034b.png

U1 is a LM35 attached to the main heatsink on the ice module (at least on the MB500 - I haven't seen where it is attached on a MB200) and the fan is one of the tiny 25mm x 25mm 12V ones that run at 60mA-ish.

 

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9 minutes ago, nilebodgers said:

You could pinch the thermostatic fan control circuit from something like the GK MB200 that uses the same ICE module.

See:

924121763_mb200fancontrolsch.thumb.png.d1e16089ac191b490fedcd4ff1a0034b.png

U1 is a LM35 attached to the main heatsink on the ice module (at least on the MB500 - I haven't seen where it is attached on a MB200) and the fan is one of the tiny 25mm x 25mm 12V ones that run at 60mA-ish.

 

Nice idea but there is no heatsink on the ASX50 but I will use that for the ASX125 module I have. I used to have a 200watt GK combo with the ASX50 in it. that had a fan running all the time.

Edited by Chienmortbb

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One of the  good things that a project like this does is teach you things you had never considered. Like using the LM35 as outlined above. Once you go above the 50ASX2 to the 125ASX2 or 250ASX2 you have a heatsink to attach the temperature sensor to.

I think maybe I should have used the 125ASX2 module I have for this project but jumping from 15-100W seemed enough. Until I reassemble the whole thing, I really won't know although the original idea was just to create a practice amp.

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OK I installed the Brightness switch and circuit last night and was surprised to find I liked it. I should say that all the subjective testing is being done with either headphones or a PA cab at the moment and I might change my opinion once the amp and cab are reunited.

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Like most things installing the LED was more involved than I thought. However it is in now. Usually the LED would be run at 20mA but that would mean the LED would run at a brightness. I find high brightness blue LEDs too bright so I am running it at 10mA. 

However I may swap it for an Red/Green/Blue LED so that I can show when the mute is on. The hole near the LED is where the mute/standby switch will be, once it arrives. 
 

965BC1E3-7E39-4FE0-A947-455771021DF8.thumb.jpeg.b456cf5ed703a97f0a9ac35b26cfc9c9.jpegI

I have decided to keep the headphone socket as a headphone socket and will install an XLR at the back. 


106BAFD9-F03E-4607-A6DB-028AD9D0DFE8.thumb.jpeg.3ffeb63a9bed00f10c61476f9f5e5a08.jpeg

I tried drilling the hole out to 10mm. I tried to ream out the hole to 24mm but it was going to take hours and was really hurting my hand. So I took the plunge and ordered a 25mm Q Max cutter. 
 

Q Max cutter. 
 

Edited by Chienmortbb
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I have been thinking about weight.This bit is boring so skip to the end if you are easily bored.  Am I the only one that has put on some during lockdown? I digress, The After Eight was fairly heavy for its size and adding a Neo speaker will not help. The 35W 8R Sica speaker is a real lightweight at 0.9Kg (2lbs). The P-Audio Neo E8-200N weighs 1.5Kg (3.3 lbs).  A gain of 0.6Kg or well over 1lb.

As the ICEPower 50ASX2 has an inbuilt SMPS (switch mode power supply), that helps as it means that the transformer could be removed. The transformer weighs approx 700g (1.5lbs) wheras the ICEPower module weighs 180G. So we pull back 520 grams meaning we are still down 80 grams. .

Of course the old amp module also had an aluminium heatsink plus all the components except the power switch and mains input,  that weighs 300 grams and includes the pots and sockets that are also on the new amp. I estimate that the PCB is approximately the same weight as the ones I have installed and the the aluminium heatsink weighs approx. half the 300 grams or 150 grams.

So my build will be about 70 grams lighter or 2.5 ozs. I will not be selling my truss just yet.

 

Of course I could have rebuilt the cabinet......... but some of the weight will be in that chassis that made it easier to build. Its a small cab so probably the weight saving would be negligible.

Edited by Chienmortbb
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4 minutes ago, Mottlefeeder said:

You also cut away some wood and added a plastic tube...

David

Good spot and of course the Vynyl covering will weigh less than the "carpet". I hope. Still it is easier to cut weight there than off my waistline. 14-15 stone now to get the 14 lbs off.

Edited by Chienmortbb

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Sorry for tghe long delays but another bout of non-Covid infections have held things up. As you could see from the last picture above, it turned my world upside down.

I have drilled the fixing holes for the D Type XLR or Speakon. I realise that I need a male XLR for DI out. The cutout for a Neutrik or equivalent D size connector is 23.9mm and I assumed a 25mm hole would be fine, it is, but only just . The 24mm cutters are harder to find and more expensive byt I am happy with the result with the 25mm.

The Phantom Power protection parts have arrived together with the new soldering iron element.

1755927925_xlrfittedrotated.thumb.jpg.20f72b743bb4eb345d041dbf7335dc4e.jpg

Now I have the Qmax cutter, ever piece of sheet metal should be nervous. I realised after I cut bthe hole that I used the cutter the wrong way around. Although it cuts a very clean hole, there is a slightly raised edge to the hole on this side although the inside hole is as smooth anything.

I am considering whether to convert the speaker jack to a speakon or leave it as is and wire the switched output to a speakon on the back, next to the XLR. I am never convinced by switching jacks but they do make life easy. Incidently I will spray the panel to obscure all disturbed or obsolete information. To be fair to Ashdown I will also take off all branding.

I am realising that although I was keen to avoid feature creep, it has crept in all the same. Next cosmetic question, which knobs. Photos of the avaible choices to follow.

Edited by Chienmortbb

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Sorry for the delay but owing to the ongoing helath issues not much has been done. The cabinet has been filled ( there were a few gouges where I tried to get thev carpet off) that will be sanded later today. Then I will look at covering the cabinet.

I have been thinking more about the weight. Smaller cabs are intrinsically lighter and as seen form the Basschat 1x12 builds, poplat or spruce ply is much lighter but with the After Eighty, the gains were assumed  to be  minimal. It uses chipboard, (roughly the same density as Birch Pl)y. I could   have gone to 15mm Poplar but the gains were assumed to be minimal compared to the increase in cost. A comment by Phil Starr  has made me think though and it seems I could have shaved anywhere between 1 and 2 Kg off the weight by going 15mm Poplar or spruce.

Still at the moment I am keeping this cab as the whole, the  unit is not overly heavy and the costs are mounting consdering that was a side project with existing parts.

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Felt a bit better this afternoon so got on with the  cabinet. I used a sone white spirit to wipe the baffle clean before painting and most of the existing paint came off. So mask it off and spray away. 
 

203A5058-6910-4F02-AAF9-70797F34087E.thumb.jpeg.16ee628ff481a81fb7da59422ccb671b.jpeg

it is still drying and needs at least one more coat but it looks better. After that I will coat the cabinet with a thin coat of PVA. The idea is to also coat the covering and let that go slightly tacky then smooth the vinyl with a warm iron on told of a towel. It may work it may be a disaster. Comments and advice welcome. Of course I will be trying it on an off it first. 

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Knobs. 
 

Originals, below have gone a little bronze, tarnished. C0E5663D-A1D5-4BF4-9A19-58799600C5E8.thumb.jpeg.012672f6a5f5bcd3dd83f686827b2833.jpeg 
The cheapo rubberised ones I used for the testing?

87875A84-F0E7-4393-9922-3A79A10CB120.thumb.jpeg.1205acc4ea48b365337c34a72b7b2ef9.jpeg

They grey Davis style?

ABFAF5A2-AE00-4D93-87D7-67C33B679771.thumb.jpeg.55aa2ea86ed02171631667aae0fa7a52.jpeg

Combination of grey and black Davis style?

CB13972B-9D45-4796-A419-E6CCC434F7EE.thumb.jpeg.e994dfd9b320204508c6c21f4338dc67.jpeg
 

Or all black Davis style?

9B57006E-0830-4F3D-9212-8E66250168E2.thumb.jpeg.c86e2aa69ee003af8f4473dd5fe2a1b6.jpeg

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On 17/06/2020 at 20:56, Chienmortbb said:

Like most things installing the LED was more involved than I thought. However it is in now. Usually the LED would be run at 20mA but that would mean the LED would run at a brightness. I find high brightness blue LEDs too bright so I am running it at 10mA. 

However I may swap it for an Red/Green/Blue LED so that I can show when the mute is on. The hole near the LED is where the mute/standby switch will be, once it arrives. 
 

965BC1E3-7E39-4FE0-A947-455771021DF8.thumb.jpeg.b456cf5ed703a97f0a9ac35b26cfc9c9.jpegI

I have decided to keep the headphone socket as a headphone socket and will install an XLR at the back. 


106BAFD9-F03E-4607-A6DB-028AD9D0DFE8.thumb.jpeg.3ffeb63a9bed00f10c61476f9f5e5a08.jpeg

I tried drilling the hole out to 10mm. I tried to ream out the hole to 24mm but it was going to take hours and was really hurting my hand. So I took the plunge and ordered a 25mm Q Max cutter. 
 

Q Max cutter. 
 

How much??????

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1 hour ago, stevie said:

How much??????

QMax cutter? About £14 including vat and delivery. . 

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2 hours ago, Chienmortbb said:

Or all black Davis style?

9B57006E-0830-4F3D-9212-8E66250168E2.thumb.jpeg.c86e2aa69ee003af8f4473dd5fe2a1b6.jpeg

These.  They look like you might see them better under difficult lighting.

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OK i have changed the DI circuit (on paper) in line with the need to protect against Phantom Power. The circuit is a cross between the original circuit outlined in Elliot Sound Products Project 14 Amplifier Bridging Adaptor and Project 152 Bass Amplifier. Incidently, I bougt the PCB from Rod Elliiot and hope that if anyone uses these ideas they also buy PCBs to keep his great resource going. Please click on the links below to go to the relevant pages on Rod's website. I have also added the ground lift switch. I have put links to all Rods projects that I have looked at plus a link to the Fender style preamp that could be used in a similar project to this.

 

Click to go to Project14 on Elliot Sound Products

Click here to see the DI out circuit on the P152 Bass Amplifier.

Link to Project27 including the alternative preamp (PCB available)

 

77835553_DIoutwithPhantomPowerprotection..png.317c1075299163ad4727222f54bae4ba.png

 

 

 

 

Edited by Chienmortbb
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3 hours ago, Chienmortbb said:

QMax cutter? About £14 including vat and delivery. . 

Aha. Your link said £75, which is why I asked. 😄

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22 hours ago, Chienmortbb said:

OK i have changed the DI circuit (on paper) in line with the need to protect against Phantom Power. The circuit is a cross between the original circuit outlined in Elliot Sound Products Project 14 Amplifier Bridging Adaptor and Project 152 Bass Amplifier. Incidently, I bougt the PCB from Rod Elliiot and hope that if anyone uses these ideas they also buy PCBs to keep his great resource going. Please click on the links below to go to the relevant pages on Rod's website. I have also added the ground lift switch. I have put links to all Rods projects that I have looked at plus a link to the Fender style preamp that could be used in a similar project to this.

 

Click to go to Project14 on Elliot Sound Products

Click here to see the DI out circuit on the P152 Bass Amplifier.

Link to Project27 including the alternative preamp (PCB available)

 

 

Project 27 works really well for a bass preamp IME. I gigged with a DIY rack preamp using his V1 board for quite a few years and that build ended up in a NAMM booth earlier this year actually. Hopefully Rod will do boards for at least some parts of his new bass preamp project as well.

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1 minute ago, Passinwind said:

Project 27 works really well for a bass preamp IME. I gigged with a DIY rack preamp using his V1 board for quite a few years and that build ended up in a NAMM booth earlier this year actually. Hopefully Rod will do boards for at least some parts of his new bass preamp project as well.

Yes his bass amp is a well thought out project, it would be nice to see some PCBs for it although the Class A/B amp would not be my chouce.

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OK so no real progress today although after a discussion with "she who must be obeyed", I have decided to use Tuffcab rather than a vinyl covering. She who must be obeyed has done some upholstery and  says that the shape is far from for a good finish with vinyl. Paint it like your other cabs she said. So as I already have to Tuffcab, it will be done soon.

I am suffering from a chest infection at the moment and have to stay clear of anything dusty, fumey and infectious. Luckily Tuffcab is water based so I can do that, probably tomorrow morning.

 

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1 minute ago, Chienmortbb said:

Yes his bass amp is a well thought out project, it would be nice to see some PCBs for it although the Class A/B amp would not be my chouce.

Agreed, but in many parts of the world including the US it would be sketchy to even publish anything with the usual SMPS supply format that so many Class D amps use. DIYaudio used to explicitly forbid it, not sure if they're still held to that or not though.

For my part, I'm deep into a tube bass amp build at the moment. Just about everything about it is a real shock after all the battery powered stuff I've been doing for the last few years, hopefully not literally though!

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