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brettpobastad
06-07-2013, 07:36 PM
...anybody got any experiences with or thoughts on the Hartke LS500 bass amp head? It's supposed to have a tube peamp but I can't find any info on the tube itself.

Elmeaux
06-07-2013, 11:51 PM
This was something I found online about the tube in the amp you describe. It apparently uses a 12AX7 Class-A Tube Preamplifier.

http://www.musiciansfriend.com/accessories/mullard-12ax7-preamp-tube

brettpobastad
06-08-2013, 09:04 AM
Thank you, El. Anybody out there have one of these?

TobiasMan
06-08-2013, 10:19 AM
Same tube in the preamp as my Eden amps, but that tube only functions in the gain setup on Eden amps, no effect on tone.

brettpobastad
06-09-2013, 09:25 AM
Thanks for the input, TM. I bought the amp last night and I'm fiddling with it right now. So far, so good.

TobiasMan
06-09-2013, 09:59 PM
There are a ton of 12AX7 tubes out there. When they are used in the preamp section, which brand makes very little difference, although some may have a bit more gain than others.

It is when the tubes are in the amp section that tube design impacts the sound. That's why guitar forums are full of intensive arguments/debates over this tube vs that tube. Since "most" bass amps are solid state in the power section, we don't normally suffer through those debates. We get to discuss strings, finger/finger wax, picks or not, and 4 vs 5 vs 6 strings instead. ;)

brettpobastad
06-10-2013, 08:42 PM
I guess I don't really know if the tube in this amp is in the preamp or the amp section. I'm still playing around with the sound of it. It is a very simple amp. One volume control. Bass, mid and treble boost. High switch and limiter. I'm running my Stingray through a Boss graph pedal. Any tips would be welcome.

TobiasMan
06-11-2013, 10:39 AM
In order to get enough power, most amps that use tubes in the power section have multiple tubes there. One tube is the norm for the preamp section.

Your LS500 is a hybrid amp, (tube preamp, solid state power amp - 350 watts into an 8 ohm load and 500 watts into a 4 ohm load). Here is a link to the Hartke site where you can also download a manual. http://www.samsontech.com/hartke/products/amplifiers/lh-series-amplifiers/lh500/ (http://[URL)

If you don't have a manual, it would be a very good idea to download, print and study it, as it has a number of interesting features that are a bit more sophisticated than just plugging in a bass and turning up the volume. ;)

It looks like you can plug either a single 4 ohm cab into either of the 1/4" output jacks on the back, or you can plug 2, 8 ohm cabs into the plugs to provide the 4 ohm load that will extract the full 500 watts from the amp. Do not plug 2, 4 ohm cabs into those jacks, as that will result in a 2 ohm load (waay to low for that amp and likely to damage it).

You could also plug a single 8 ohm cab into one of the jacks and the amp will produce 350 watts.

Looks like a nice amp. Congrats!

brettpobastad
06-12-2013, 03:52 PM
Thanks for the info, T-man! I have the manual and the amp is in 'like new' condition. It came in a Gator 2-space amp rack. For $150, I think I got a pretty good deal. However...

I can't get it to sound good or even generate enough power (read: volume). I tried running it through the speaker of my Sunn 1X15 combo amp. The speaker is a 4 ohm Peavey Scorpion. At a volume level of about seven or eight, the speaker starts to overload badly and it isn't very loud. It's even worse when I run my Stingray through a Boss volume pedal first. I tried both the active and the passive inputs. The passive input generates a little more volume but still not even close to what I expect from a 500 watt amp. I tried running an 8 ohm 1X15 cab out of one of the speaker jacks and then two 8 ohm 1X15 cabs, one each out of each separate speaker jack. In both cases, the speaker(s) did not 'break up' or overload but the sound wasn't great and still not generating enough power (volume). My 200 watt Sunn combo (using the same Peavey Scorpion) is much louder and doesn't overload the speaker. All these tests were done at practice with loud guitar and drums.

brettpobastad
06-12-2013, 04:01 PM
A couple of questions and comments:

A 4 ohm cab plugged into one of the speaker jacks in the back is 4 ohms. An 8 ohm cab plugged into one of the speaker jacks in the back is 8 ohms. Two separate 8 ohm cabs plugged into each of the two speaker jacks (parallel) is still an 8 ohm load, correct? Plugging in one 8 ohm cab to one of the speaker jacks and than plugging in the other 8 ohm cab to the first cab (series) is then 4 ohms, correct? Or do I have that backwards?

Also... why does the limit and overload light come on on my Sunn combo even though I am only using it as an extension speaker and the amp itself isn't even plugged in?

TobiasMan
06-12-2013, 07:18 PM
The amp is likely wired in parallel, so either two, 8 ohm cabs in one output, or one 8 ohm cab in each output will still be 4 ohms and result in the maximum power. If you have two 8 ohm cabs in one output, you cannot add another cab to the amp, as the impedance will be too low (< 4 ohms). "IF" the amp was wired so that the cabs were connected in series, (not likely at all), they would create a 16 ohm load and a very low power output.

So yes, if you have one 8 ohm cab in each plug that results in the 4 ohm minimum load that the amp can handle. If you daisy chain the cabs into a single output (amp-> cab 1-> cab 2) they will also create a 4 ohm load. Once you have reached the 4 ohm load, don't add any more cabs to the amp!

How are you connecting the Sunn combo to the Hartke? Does the Sunn combo have an input that allows you to connect directly to the internal speaker, bypassing the amp? If so, then you could feed the Hartke signal from one of the outputs to the Sunn speaker, but the impedance of the Sunn speaker has to be considered when looking at your ohm load on the Hartke. What impedance is the speaker in the Sunn? Some combos are already 4 ohm to get the most out of the amp. If the Sunn has an 8 ohm speaker then you can only connect one more 8 ohm cab to the Hartke. If you double up two 8 ohm speakers, or a single 4 ohm cab on the remaining output, you would be running a 2.6 ohm load, (too low!) and that could damage the amp. If the Sunn does not have an input that goes directly to the speaker, you cannot drive the speaker that way.

An alternative would be to use the Sunn as a slave amp, meaning you have the Sunn amp turned on and are using the signal from the Hartke as the input signal to the Sunn. To do this you have to take the signal from the preamp section of the Hartke. There appear to be only two options for accessing the preamp signal from the Hartke, either from the DI out, (which would be problematic because that output is an XLR connector, and also is a quite low level signal -10dB, optimised for a sound board input), or from the Effects Send on the back of the amp, which can feed an external amplifier that can accept a +4dB signal (this would appear to be the most likely route). Either of those signals would connect to the input of the Sunn. You would then use the Sunn amp volume to balance the volume between the two units.

You can not take the powered, speaker out signal from the Hartke and feed it to the amp input in the Sunn. That signal would be way too powerful for the Sunn input.

I have no idea why any lights should come on in the Sunn if it isn't plugged in and you are simply feeding the Hartke signal direct to the speaker itself. I have no idea what might happen if you fed the Sunn amp input with Hartke powere speaker output.

If the Sunn does not have an input to its speaker that bypasses the amp, then you can't feed that speaker with a speaker out from the Hartke. You'd have to try to use the Sunn as a slave amp.

brettpobastad
06-12-2013, 07:36 PM
Right on. Thanks T! I wired an output jack on the Sunn combo myself so I could use it as an extension cabinet. I have used it that way in the past with a Beringer BX3000t amp head and it works just fine in that capacity. I left everything else connected so that might be why the overload and clipping lights come on. To reiterate, I use the Sunn (with a 4 ohm Peavey Scorpion speaker) as a cabinet only. I do not plug in or turn on the Sunn amp itself. Thanks again for the information.

TobiasMan
06-13-2013, 12:33 AM
Good,
If you plug in the Sunn speaker (4 ohm) you can't add any more speakers to the Hartke, as it is already then seeing a 4 ohm load.

Still puzzled as to where the electrical current comes from to light up the Sunn lights. Simply powering the speaker should not result in any power going back to the amp.

The only way to add more cabs to the rig would be to run the Sunn as a slave amp and then you still have the 4 ohm capacity of the Hartke for more cabs (like 2, 8 ohm cabs!!! ;) which would be noticeably louder than a single cab).

Also don't know why you are not getting good volume out of a 500 watt rig, unless you were running too many speakers and were running too low an impedance for the amp.

Not all speakers produce the same level of "loud" from the same power. Do you have any idea what the sensitivity of the speakers you are using?

Sensitivity is generally measured as xx dB for 1 watt at 1 metre distance, which is a measure of the volume the speaker would create with 1 watt of power, measured at 1 metre distance. I am aware of cabs that range from sensitivity ratings from the low 90 dBs (or even lower) to well over 105 dB. My two Eden cabs are rated at 104 and 106 dB, so at the same power level, they are about twice as loud as a 90 dB cab.

For comparison, the sensitivity ratings for Hartke Hybrid and XL cabs with the aluminium drivers run from 96 dB to a high of 99 dB. From what I can see, Peavey Scorpion, 4 ohm speakers run from 99 dB for the 10" drivers, to 100 dB for their 12" and 15" units.

brettpobastad
06-13-2013, 09:10 AM
I have been messing around with it at home and it sounds much better. The only thing I changed was the speaker cable. My gut feeling is that the speaker and cab and wiring (even though it is a single 4 ohm 1X15 speaker) is not compatible with this amp. A friend is bringing over a couple of 4X10 cabs to try out.