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Posted

[url="http://www.ebay.co.uk/itm/SOUND-CITY-120-MK4-HEAD-GUITAR-AMP-ALL-VALVE-/180707580658?pt=UK_MusicalInstr_Amplifiers_RL&hash=item2a1302daf2"]Gogo gadget running a valve amp into no load.[/url]

Posted

[quote name='neepheid' post='1332309' date='Aug 8 2011, 04:15 PM']I don't know what that means, other than I'm guessing it's a bad thing and to expect fireworks/loss of magic smoke soon?[/quote]

If you have a valve amp on with no speaker attached, all sorts of bad things can happen, as the equilibrium of the circuit is reliant on the output transformer having a load on it (completing the circuit of its secondary winding). Having a speaker and the impedance selector is wrong but not fatal, having no load at all can really mess things up, like the amp goes into oscillation and totally cooks itself.

Posted

[quote name='Mr. Foxen' post='1332314' date='Aug 8 2011, 03:17 PM']If you have a valve amp on with no speaker attached, all sorts of bad things can happen, as the equilibrium of the circuit is reliant on the output transformer having a load on it (completing the circuit of its secondary winding). Having a speaker and the impedance selector is wrong but not fatal, having no load at all can really mess things up, like the amp goes into oscillation and totally cooks itself.[/quote]
Could this kind of thing cause all the capacitors inside to lose their innards? I had a Laney Klipp when I was a kid and I used to wire all sorts of different speakers to it, in all kinds of configurations, without knowing anything about impedance or valves, in fact I still know bugger all about valves... I just know that one day I saw the magic blue smoke coming out and when I opened it up (I used to open everything electronic up when I could) all the capacitors had popped open.

I never thought to get it repaired. I just chucked it and ended up buying the most soulless Carlsboro Bass amp I've ever heard. I hated that thing.

Posted (edited)

"I never thought to get it repaired. I just chucked it and ended up buying the most soulless Carlsboro Bass amp I've ever heard. I hated that thing."


was it a carlsboro "stingray" amp ? I had one of those and REALLY hated it. once I could afford to, I didnt even bother trying to sell it, gave it away instead (shudder) hateful thing

Edited by witterth
Posted

[quote name='witterth' post='1332342' date='Aug 8 2011, 03:37 PM']"I never thought to get it repaired. I just chucked it and ended up buying the most soulless Carlsboro Bass amp I've ever heard. I hated that thing."


was it a carlsboro "stingray" amp ? I had one of those and REALLY hated it. once I could afford to, I didnt even bother trying to sell it, gave it away instead (shudder) hateful thing[/quote]
I wasn't sure what it was called, I sold it on a very long time ago, so I went looking and found this:

[url="http://www.ebay.co.uk/itm/CARLSBRO-STINGRAY-BASS-AMP-V-RARE-VINTAGE-80S-/150629833084"]http://www.ebay.co.uk/itm/CARLSBRO-STINGRA...S-/150629833084[/url]

It's the same one as that and that says Stingray. Horrible, horrible thing.

Posted

[quote name='KingBollock' post='1332326' date='Aug 8 2011, 04:24 PM']Could this kind of thing cause all the capacitors inside to lose their innards? I had a Laney Klipp when I was a kid and I used to wire all sorts of different speakers to it, in all kinds of configurations, without knowing anything about impedance or valves, in fact I still know bugger all about valves... I just know that one day I saw the magic blue smoke coming out and when I opened it up (I used to open everything electronic up when I could) all the capacitors had popped open.[/quote]

Don't still have it somewhere do you? Those caps are easy to replace, an I have a big bag of them I just ordered. I don't know if impedance fun can blow the filter caps, usually it is valves an resistors that go other than the tranny itself. They did use pretty cheap caps I think, a ton of smaller ones instead of big cans.

Posted (edited)

[quote name='Mr. Foxen' post='1332369' date='Aug 8 2011, 03:52 PM']Don't still have it somewhere do you? Those caps are easy to replace, an I have a big bag of them I just ordered. I don't know if impedance fun can blow the filter caps, usually it is valves an resistors that go other than the tranny itself. They did use pretty cheap caps I think, a ton of smaller ones instead of big cans.[/quote]
I wish I did. I threw it out about 22 years ago, I was only 13 or 14. I can't remember how many caps were in it but there was a line of them, they were about the size of C cell batteries, from what I remember.

Edited by KingBollock
Posted

[quote name='KingBollock' post='1332532' date='Aug 8 2011, 06:41 PM']Not as rare as they should be. Unless you count landfill sites...[/quote]

They are great if you don't break them.

Posted

[quote name='Mr. Foxen' post='1332627' date='Aug 8 2011, 06:46 PM']They are great if you don't break them.[/quote]
'Ang on a minute, you've lost me. Are you talking about the Laney Klipp or the Carlsboro Stingray? I didn't break the Stingray and it's that that I meant wasn't rare enough, I assumed you meant the Stingray when you said they weren't really rare because it said they were rare on that Ebay page. I didn't break it, I just hated it. It was the Laney that I broke and I loved that.

Posted

[quote name='KingBollock' post='1332632' date='Aug 8 2011, 07:51 PM']'Ang on a minute, you've lost me. Are you talking about the Laney Klipp or the Carlsboro Stingray? I didn't break the Stingray and it's that that I meant wasn't rare enough, I assumed you meant the Stingray when you said they weren't really rare because it said they were rare on that Ebay page. I didn't break it, I just hated it. It was the Laney that I broke and I loved that.[/quote]

The Sound City in the original post is the one I'm referring to. 'Rare' is part of the very limited description. I know they aren't rare because I have 9 of them sat about my house.

Might be able to sort out a new rebuilt Klipp for you going forward.

Posted

[quote name='Mr. Foxen' post='1332638' date='Aug 8 2011, 07:54 PM']The Sound City in the original post is the one I'm referring to. 'Rare' is part of the very limited description. I know they aren't rare because I have 9 of them sat about my house.

Might be able to sort out a new rebuilt Klipp for you going forward.[/quote]

MB1. :lol:
:) 9 ? :) are you attempting to make them rare?

Posted (edited)

[quote name='Mr. Foxen' post='1332638' date='Aug 8 2011, 06:54 PM']The Sound City in the original post is the one I'm referring to. 'Rare' is part of the very limited description. I know they aren't rare because I have 9 of them sat about my house.

Might be able to sort out a new rebuilt Klipp for you going forward.[/quote]
Ah, sorry, I got a bit lost when I assumed you were commenting on my post.

I remember seeing a photo of your Sound City Amps and the Klipp in there (I'm assuming (again!) it was your photo, I saw it just after I joined here), it caused a bit of a nostalgia trip. Unfortunately there's no room in my life for one now, happy with what I have now and it's all rack mount stuff. I do regret having chucked it but it was over 20 years ago now, I'm just about over it!

Edited by KingBollock
Posted

[quote name='Mr. Foxen' post='1332314' date='Aug 8 2011, 04:17 PM']If you have a valve amp on with no speaker attached, all sorts of bad things can happen, as the equilibrium of the circuit is reliant on the output transformer having a load on it (completing the circuit of its secondary winding). Having a speaker and the impedance selector is wrong but not fatal, having no load at all can really mess things up, like the amp goes into oscillation and totally cooks itself.[/quote]
Am I missing something? I've been told my a few techs that it's not damaging until a load is put on the amp, & since there's no instrument lead plugged in then there is no load being applied?
I know virtually nothing about these things, just repeating what I was told?

Posted

[quote name='Big_Stu' post='1334025' date='Aug 9 2011, 07:19 PM']Am I missing something? I've been told my a few techs that it's not damaging until a load is put on the amp, & since there's no instrument lead plugged in then there is no load being applied?
I know virtually nothing about these things, just repeating what I was told?[/quote]


Won't make a difference, simple rule of thumb is you need a matched load on an all valve amp whether you have an instrument plugged in or not.

Posted

Bit of a moot point I know, since I can't think of any reason why you'd deliberately do such a thing, but being nosey and between my reply & yours I did a search & there are mnay forums of folk asking for advice after firing up an unplugged valve amp & the general consensus seems to be that there should be no damage done unless an instrument was played through it.
All talk I've found about how deadly to an amp it is are saying that it's the load (ie an input signal from an instrument) that does the damage.

Personally I check & double-check all connections & settings before that mains goes on; I never take chances & see no reason to. I'd keep on looking for an SC rather than chance that the one in the auction has been further mis-treated.

Posted

The preamps in these put out loads of noise as they are which will feed the power section, and without a load, it throws off the equilibrium of the amp so it can go into oscillation (like mine was doing, putting out about 5hz, so I could see me speakers going in and out) and drive itself to full tilt. Basically, in an ideal world with a perfectly working and designed amp it would be fine, but also it would be plugged into a load.

If you want a SC, I have one going that is totally rebuilt, pretty much using them without a fair bit of rebuilding is mistreatment, there are a few time sensitive components, like the resistors an the capacitors and the valves. An dirt sensitive ones like the pots and the switches. And dropping sensitive ones like the chassis and the box. And the transformers don't like being switched to wrong voltage or impedance respectively. The turret board and wires seem fine though.

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