little Mark - BIG problem

[playbass]

I recently bought a Little Mark II from another BCer. I tried it out at a reheasal on Saturday (You can imagine how annoying I was as I bragged about how light it is to the guitarist stuggleing with a HUGE fender amp.) I'd been playing for about an hour with the gain and master both at half way when the sound completely cut out. (There were no pops, bangs or other nasty sounds and there was no smoke, fire or bad smells.) The power light was still on though. After about a minute it started working again. About half an hour later this happened again. But I'm pleased to say it started working again after it had a little rest. This wasn't a problem as it was just a practise, but could be very embarrasing at a gig.

The amp was sitting on top of my cabs and it was not in a rack. Can anyone shed any light on what's going on here and if they've experienced something similar? (I was playing a 4 string active jazz bass and the amp was connected to 2 8Ohmn 12" cabs.)

Thanks for any help.

(Not quite so smug now about my light-weight, but slightly part-time amp ).

[wateroftyne]

Hmm... sounds like a classic thermal issue. Did you have anything sitting on top of the amp? A pedal, or anything?

[playbass]

[quote name='wateroftyne' post='385345' date='Jan 19 2009, 08:26 PM']Hmm... sounds like a classic thermal issue. Did you have anything sitting on top of the amp? A pedal, or anything?[/quote]

Little Mark was just sitting on top of the cabs with nothing on top or next to him. The case was quite warm but no way near as warm as the Ashdown Superfly I had before (and that performed with no problems). I wondered if it was a thermal safety cut out, but the fan was running unobstructed and the room wasn't hot and there were no stage lights in the room. Could the thermal cut out be a little overly cautious?

[Mr. Foxen]

Chocked with dust inside? Might find carpet in there.

[playbass]

[quote name='Mr. Foxen' post='385417' date='Jan 19 2009, 09:16 PM']Chocked with dust inside? Might find carpet in there.[/quote]

It's very clean... and it has an ironically large heat sink (if it is a thermal problem).

(Thanks for the suggestion!)

Edited January 19, 2009 by playbass

[yorks5stringer]

Its a problem that has been reported by a small % of users both here and in the USA too, although it has usually been an issue when the amp was brand new. Maybe a call to the UK distributors Proel Int? I've usually found them quite helpful. Are you sure the cab was the correct impedance as they really do not like going below 4 ohms?

Edited January 20, 2009 by yorks5stringer

[Soulfinger]

[quote name='yorks5stringer' post='385720' date='Jan 20 2009, 10:22 AM']Its a problem that has been reported by a small % of users both here and in the USA too[/quote]
And by some folks on the Swiss(German/Austrian) bass forum I frequent, among them F1 and LM250 users.

Some of them have sent their amps back to Markbass who are very interested in finding out what´s happening. So you´re not alone. Some blame the D-class power switching but the jury is still out ATM...

You´re not using Eden cabs by any chance?

[playbass]

[quote name='Soulfinger' post='386463' date='Jan 20 2009, 05:42 PM']And by some folks on the Swiss(German/Austrian) bass forum I frequent, among them F1 and LM250 users.

Some of them have sent their amps back to Markbass who are very interested in finding out what´s happening. So you´re not alone. Some blame the D-class power switching but the jury is still out ATM...

You´re not using Eden cabs by any chance?[/quote]


I'm sure the cabs are 8 Ohmns; they're a pair of EA CXL-112.

I'm a bit gutted as everyone keeps going on about how good they are (and I certainly am pleased with the sound, power and weight) meanwhile the ashdown superflys get slagged off for being under-powered and unreliable (and mine never let me down, even if I was tempted to use it as a plate warmer).

I've sent an email to Markbass (their auto responder tells me they'll soon be back from NAMM) and I'm just waiting for the technical department of Proel to finish unloading a lorry (so their receptionist tells me).

Thanks for the help.

[hatori]

Check the wiring in your cabs for loose connections/dry joints.

[gafbass02]

My first one cut out for short periods from new, proel sent a new one straight away.

[playbass]

[quote name='hatori' post='386568' date='Jan 20 2009, 07:08 PM']Check the wiring in your cabs for loose connections/dry joints.[/quote]

Are you suggesting it's a problem with the cabs and not the amp? Or that bad connections in the cabs could cause the amp to cut out?

[quote]"My first one cut out for short periods from new, proel sent a new one straight away."[/quote]

Maybe I should have bought a new one

[jonny-lad]

I had a minor problem with mine when I used a new speaker cable. It had unbranded speakon connectors which weren't making good enough contact in the speaker output that accepts both speakon and jack leads - if I wiggled it about the sound would come on and off. There was nothing wrong with the speaker cable other than the fact that it wasn't well suited to that type of socket (it worked fine in regular speakon sockets).

I was lucky in that I had used the amp without any problems for a while, so I could identify the cause easily. It would be worth trying some different speaker cables before sending it away for repairs.

[alexclaber]

[quote name='playbass' post='386481' date='Jan 20 2009, 05:54 PM']I'm sure the cabs are 8 Ohmns; they're a pair of EA CXL-112.[/quote]

Check with EA about the real world impedance of these - I have a feeling that in the regions of high power demand it's lower than you'd expect for a typical nominal 8 ohm cab. I believe I read something about this ages ago and certainly the transmission line design would tie in with lower impedance in the bass register. This could cause overcurrent problems at higher volumes, which does tend to be a problem with ultra-lightweight amps due to the power supply being as small as is possible whilst still achieving the power specs with typical loads.

Alex

[skankdelvar]

The bloke who does my amps has seen a number of Marks with this problem, which he puts down to the D-class power switching as noted by Soulfinger above.

[playbass]

[quote name='skankdelvar' post='386681' date='Jan 20 2009, 08:29 PM']The bloke who does my amps has seen a number of Marks with this problem, which he puts down to the D-class power switching as noted by Soulfinger above.[/quote]

Does this mean an amp technician could fix the problem or is it just a 'characteristic' of these amps?

[quote]Check with EA about the real world impedance of these - I have a feeling that in the regions of high power demand it's lower than you'd expect for a typical nominal 8 ohm cab. I believe I read something about this ages ago and certainly the transmission line design would tie in with lower impedance in the bass register. This could cause overcurrent problems at higher volumes, which does tend to be a problem with ultra-lightweight amps due to the power supply being as small as is possible whilst still achieving the power specs with typical loads.

Alex[/quote]

I'm gonna check this out. THANKS!

[yorks5stringer]

[quote name='jonny-lad' post='386606' date='Jan 20 2009, 07:35 PM']I had a minor problem with mine when I used a new speaker cable. It had unbranded speakon connectors which weren't making good enough contact in the speaker output that accepts both speakon and jack leads - if I wiggled it about the sound would come on and off. There was nothing wrong with the speaker cable other than the fact that it wasn't well suited to that type of socket (it worked fine in regular speakon sockets).

I was lucky in that I had used the amp without any problems for a while, so I could identify the cause easily. It would be worth trying some different speaker cables before sending it away for repairs.[/quote]

I had a similar issue too with mine but wouldn't that have been obvious to the OP as the sound would be cutting in and out? I was thinking more around wrong impedance=overheating amp=thermal cut-out.
There's a long thread on that US basschat thingy about it, goes on about 35 pages or so.....!

[playbass]

[quote name='yorks5stringer' post='386719' date='Jan 20 2009, 08:55 PM']I had a similar issue too with mine but wouldn't that have been obvious to the OP as the sound would be cutting in and out? I was thinking more around wrong impedance=overheating amp=thermal cut-out.
There's a long thread on that US basschat thingy about it, goes on about 35 pages or so.....![/quote]


Well I've just been to talkbass [url="http://www.talkbass.com/forum/showthread.php?t=415542&highlight=little+mark+thermal"]http://www.talkbass.com/forum/showthread.p...le+mark+thermal[/url] (will this get me thrown off basschat?!) and it seems that my lovely EA cabs are to blame Someone claimed that although they are labelled as 8Ohm they are closer to 6! Surely that could be dangerous? At least the amp has a sefty cut out... and this all means the Little Mark is fine!

Not really sure what I'm gonna do. I can't go gigging with a amp that's gonna cut out any second.

I REALLY want to say a BIG THANKS to everyone for their help on this. You've probably saved me a lot of time and maybe money too. Cheers.

Edited January 20, 2009 by playbass

[skankdelvar]

[quote name='playbass' post='386712' date='Jan 20 2009, 08:52 PM']Does this mean an amp technician could fix the problem or is it just a 'characteristic' of these amps?[/quote]

Sorry, don't know. I'll ask him when I next see him.

[dave_bass5]

Ive had my MB heads for a few years now and only had one problem, with my LMII, and that was it kept cutting out at a rehearsal one night.
Only when i really dug in or popped (yeah, i know i shouldn't) but it turned out it was down to the studio's cab, nothing wrong with the amp. This was about a year ago and its been fine ever since.

Just thought I'd mention it.

[dave_bass5]

[quote name='Soulfinger' post='386463' date='Jan 20 2009, 05:42 PM']And by some folks on the Swiss(German/Austrian) bass forum I frequent, among them F1 and LM250 users.

Some of them have sent their amps back to Markbass who are very interested in finding out what´s happening. So you´re not alone. Some blame the D-class power switching but the jury is still out ATM...

You´re not using Eden cabs by any chance?[/quote]

Im pretty sure the LM doesn't use a D class power section, just the F1.

[dub]

I wouldn't give up on your amp and clxs just yet.

I had a similar problem which came and went unpredictably. I blamed the bass, got a new preamp and then it happened again, so I blamed my Markbass SA450.
As it turned out, it was a lead. I was just fooled because it didn't crackle like a lead problem. They were good quality leads and were nearly new.
I should have known better, but I was totally convinced it was the amp, until I bought new leads. It hasn't happened since!

It would be well worth trying different leads.
If it still happens with the new leads, try using one cab on it's own, if that works perfectly then I guess it could be the impedance.

You could always get an eden amp, they can handle down to 2ohms.

Edited January 21, 2009 by dub

[playbass]

[quote name='dub' post='387669' date='Jan 21 2009, 04:15 PM']I wouldn't give up on your amp and clxs just yet.

I had a similar problem which came and went unpredictably. I blamed the bass, got a new preamp and then it happened again, so I blamed my Markbass SA450.
As it turned out, it was a lead. I was just fooled because it didn't crackle like a lead problem. They were good quality leads and were nearly new.
I should have known better, but I was totally convinced it was the amp, until I bought new leads. It hasn't happened since!

It would be well worth trying different leads.
If it still happens with the new leads, try using one cab on it's own, if that works perfectly then I guess it could be the impedance.

You could always get an eden amp, they can handle down to 2ohms.[/quote]

Thanks for the suggestions.

I'm very tempted to go the route of getting an EA iamp since they should match well with the cabs (which I love) and I think they go down to 2 ohms too.

There may well be a Little Mark II appearing on the for sale section of this site very soon if anyone's interested. just make sure you're not using EA cabs!

Just out of interest how warm do Little Marks normally get when gigging them? When mine cut out it was quite warm and like I said I certainly wasn't pushing it; the master and gain were both only half way and that is far from clipping with my bass.

[LimeB]

Why did you ask about the eden cabs? As I just have had this experience and I was running the LMII special edition through 2 eden d112xlt cabs.

[gafbass02]

Very interesting about the cabs actually presenting a lower load than advertised. Bit worrying in a way.

Edited February 13, 2012 by gafbass02

[whynot]

I purchased a used LM head 3 or 4 years back. Worked fine when I paid for it but nothing when I got home.
Checked the inside and a connection to a board inside had come away. Just a simple plug back in, but was surprised how loose it was. Maybe worth double checking inside for any obvious loose connections.