Helix and (real) Marshall-Cab 1960AX (4x12' 100W 16 Ohm)

[AMountain]

I want to connect my Marshall-Cab with 4 Greenbacks (100W, 16 Ohm) to the Helix. What i need is a class d amp with 100-200W mono @ 16 Ohm. I was told 200W would be better with Class d amps, but i didn't understand the explanation.

 

However, i find many of such amps for 4 and 8 Ohm (like Seymour Duncan Power Stage 170) and as good as none that provide 100-200W at 16 Ohm. So i hoped to find here people that already did that and can recommend a precise amp.

[rvroberts]

If it's 16ohm speakers - which they mostly are, you just need to wire it in parallel to make it 4 ohms.

https://www.thegearpage.net/board/index.php?threads/how-to-rewire-4-16-ohm-speakers-for-a-4-ohm-head-and-speaker-choices.1931962/

[AMountain]

55 minutes ago, rvroberts said:

If it's 16ohm speakers - which they mostly are, you just need to wire it in parallel to make it 4 ohms.

https://www.thegearpage.net/board/index.php?threads/how-to-rewire-4-16-ohm-speakers-for-a-4-ohm-head-and-speaker-choices.1931962/

No, because i have my 100W-SLPs to which the cab belongs (which i want at any time to connect and run too). So i will not start to open the cab for to change there the wiring of the speakers. Or i get a class d - amp that works with at least 100W at 16 Ohm, or i don't do it.

[rvroberts]

If you don't want to rewire - you don't want to rewire!

But your amp will run into 4ohms just fine according to the Marshall site??

So there is a simple answer if you want it!

[waymda]

So your cab will take 100 watts @ 16 ohm, but you want an amp that will feed it up to 200 at 16 ohm?

 

I can only presume you want it increadibly effing loud and/or have the ability to fry the coils of the speakers.

 

The class of the amp is irrelevant, except that class D amps are modern solid state and light - so long as you're considering RMS not peak wattage rating.

 

Wattage will halve with each doubling of impedance - ie 400 watt@ 4 ohm = 200 watt @ 8 ohm = 100 watt @ 16 ohm

 

So, maybe you've been told to get a 200 watt amp @ 8 ohm?

 

Anyway - even 100 watts @ 16 ohms is pretty high end and you may need to try something lower spec and see if it works for you before forking out the $ to get the sort of power your talking

 

I have a stereo valve power amp that will bridge to 100 watts @ 16 ohms if you want to spend some real $ :)

 

 

 

[AMountain]

39 minutes ago, rvroberts said:

If you don't want to rewire - you don't want to rewire!

But your amp will run into 4ohms just fine according to the Marshall site??

So there is a simple answer if you want it!

 

Thank you for your idea, but i like the sound and the feel of my amps & cabs at 16 Ohm. Out of question to change that.

 

So, simple or complicated - it's more complicated to rewire the cabs than to buy an amp that suits the demand -, it's not the answer because that simply wasn't the question. 

 

The question was and is precisely if there are people here that can recommend class-d-amps that give 100-200W at 16 Ohm. I found one meanwhile, the Palmer Macht 402, it gives 200W mono at 16 Ohm. The price is reasonable. But i wait if some people can show me alternatives and i am too hoping that people can tell me their practical impressions, soundwise. 

 

 

 

[waymda]

You might be best searching a Palmer forum for that - do you think there's a large number of people here with your configuration to provide info?

 

And whilst I love your precision in the question, the answer is not precise. Its an opinion based on the very limited info you've provided.

 

Mr Google found me a bunch of info about that amp - none of it here. Suggest you reference these.

 

https://www.thomann.de/gb/palmer_macht_402.htm

https://www.kemper-amps.com/forum/index.php?thread/25526-palmer-macht-402-specialized-guitar-power-amp/

https://www.google.com/search?q=Palmer+Macht+402%2C&rlz=1C1CHFX_enAU660AU660&oq=Palmer+Macht+402%2C&aqs=chrome..69i57&sourceid=chrome&ie=UTF-8

 

 

 

 

52 minutes ago, AMountain said:

 

Thank you for your idea, but i like the sound and the feel of my amps & cabs at 16 Ohm. Out of question to change that.

 

So, simple or complicated - it's more complicated to rewire the cabs than to buy an amp that suits the demand -, it's not the answer because that simply wasn't the question. 

 

The question was and is precisely if there are people here that can recommend class-d-amps that give 100-200W at 16 Ohm. I found one meanwhile, the Palmer Macht 402, it gives 200W mono at 16 Ohm. The price is reasonable. But i wait if some people can show me alternatives and i am too hoping that people can tell me their practical impressions, soundwise. 

 

 

 

 

[AMountain]

35 minutes ago, waymda said:

So your cab will take 100 watts @ 16 ohm, but you want an amp that will feed it up to 200 at 16 ohm?

 

I can only presume you want it increadibly effing loud and/or have the ability to fry the coils of the speakers.

 

The class of the amp is irrelevant, except that class D amps are modern solid state and light - so long as you're considering RMS not peak wattage rating.

 

Wattage will halve with each doubling of impedance - ie 400 watt@ 4 ohm = 200 watt @ 8 ohm = 100 watt @ 16 ohm

 

So, maybe you've been told to get a 200 watt amp @ 8 ohm?

 

Anyway - even 100 watts @ 16 ohms is pretty high end and you may need to try something lower spec and see if it works for you before forking out the $ to get the sort of power your talking

 

I have a stereo valve power amp that will bridge to 100 watts @ 16 ohms if you want to spend some real $ :)

 

 

 

I want it loud, yes, of course. And i have several tube-amps at home (50W and 100W), they have FX-loop where i can enter with the Helix if i want to put a pre-amp-simulation before and run my Marshall-cab this way.

 

Class-d -guitar-amps are extremely light weight, extremely efficient and if made for this layout, extremely good for neutral sound (FR) ---- I do not buy a Helix for to put then some common amp behind that will colour the sound. As alreadymentioned, i have several tube-amps, can enter there in FX if i want to. So thank you very much for your offer, but i do not need your stereo valve poweramp. What i am looking for and what i want is minutiously described in my first post, please read it twice and trice if it must be before to answer.

 

I know the laws of Ohm. And you cannot do this with any amp. For example, the SeymourDuncan powerstage 700 (guitar-class-d - amp) is permitted for 4 and 8 Ohm, explicitly not for 16. There are technical causes for that, i read them, but i am not technician enough for to have understood and memorized it in one read: Has technically to do with the chips, the voltage, and sonically with some filters that are apt for 8 but wouldn't be perfect for 16 Ohm.

On the other hand, there is the Palmer Macht 402 guitar-class-d-amp which explicitly (manual) is permitted to run at 16 Ohm: Or with 2x50W or switched to "bridged" 1x200W. 

 

Now, 200 W on 100W speakers: I read somewhere - but did not understand why - that class-d amps shall have the double Wattage of the speakers. If somebody can (dis-/)approve and explain that beside question shortly, s/he is welcome to do it.

 

But i know that it is all in general better (if you listen loud) to run a bigger amp with more little speakers than the inverse: Better a 100W amp with 50W speakers than a 50W-amp with 100W-speakers.

Of course, you have to know where you stop to turn louder. But i always have had stronger amps than speakers, at home and in my car. So i am pretty sure i will not burn my holy Marshall-cab with this Palmer Macht 402, i will know when it's loud (as old Marshall SLP 1959 user, there is no question about that).

 

But the Palmer is the only my demands suiting amp i found until now. And i would be interested to know if there are people that have experiences with that amp, or with alternative amps.

 

 

[AMountain]

:D We shouldn't speak (/write) at the same time, waymda. Me too, i am surfing through Mr.Googles limited & "optimized" (cough cough) spaces but have not found much. To suppose that specially in line 6 -Forums with the helix could be more people that tried that was IMHO not completely stupid. The more the fractalaudio forum, special axe-forum, and yea, the Kemper-Forum. I too tried to get an answer in the Marshall-forum.

 

Back to the actual topic. Beside the Palmer, i found meanwhile the Matrix GT1000, 2x 150W @ 16 Ohm, so i could - would have to - connect two cabs. And it costs the double of the Palmer. So the Palmer is the only my demands suiting amp i found until now. Still i would be interested to know if there are people that have experiences with that amp (or the Matrix), or with alternative amps.

[AMountain]

*whistling* Sorry, but i must copy&paste that, on the Matrix GT: We've also added a dedicated output for bridged mode, so no special cables are necessary to deliver the full mono power of the amplifier into any impedance of 8 ohms or over. The GT1000FX still has the same ability to handle all impedances 4 ohms and over including mis-matched loads giving you the widest choice when using your favourite cabs and speakers. Running a 2x12 cab with an 8 ohm and 16 ohm speaker in mono or running a 4 ohm cab on one side and a 16 ohm cab on the other in stereo mode is no problem for the GT1000FX! The amplifier features extensive protection circuitry ensuring it is protected from loudspeaker short circuits and miswiring as well as indicators for protection, bridged-mode and signal lights showing the output signal strength. The Matrix GT1000FX takes the Matrix line of products to a whole new level, way beyond 11. (https://usa.matrixamplification.com/gt-1000-fx-1u.html)

 

Well, well, is that too possible with the Palmer, does somebody have practical experience with it? I believe to remind i read it has limiters, providing clipping.

[brue58ski]

Correct me If I'm wrong (and I could be), but it's my understanding that the main thing you do not want, is a higher ohm amp going into a lower ohm speaker. So you wouldn't want a 8 ohm amp going into a 4ohm speaker. The lower ohmage results in the speaker drawing more current which will probably damage your amp. But it's OK to have a lower ohm amp going into a higher ohm speaker. So you could have a 4 ohm amp going into an 8 ohm speaker BUT the power output of the amp will be halved resulting in less volume. You may have already tried that and had the lower volume so you want a power amp that matches better. You may have mentioned that as well. So you should be able to use the amps you have, it just won't be as loud i.e. efficient. I do not have an answer as far as what amp to use in our situation.

[AMountain]

13 hours ago, brue58ski said:

Correct me If I'm wrong (and I could be), but it's my understanding that the main thing you do not want, is a higher ohm amp going into a lower ohm speaker. So you wouldn't want a 8 ohm amp going into a 4ohm speaker. The lower ohmage results in the speaker drawing more current which will probably damage your amp. But it's OK to have a lower ohm amp going into a higher ohm speaker. So you could have a 4 ohm amp going into an 8 ohm speaker BUT the power output of the amp will be halved resulting in less volume. You may have already tried that and had the lower volume so you want a power amp that matches better. You may have mentioned that as well. So you should be able to use the amps you have, it just won't be as loud i.e. efficient. I do not have an answer as far as what amp to use in our situation.

 

Hello brue58ski

No, with tube(aka valve)amps for example, it's the reverse and solely in a very little ratio (1.5-2 : 1, not more): So to a tubeamp, never connect speakers with higher impedance, if at all, only with lower impedance and only in 1.5 (~2) : 1 ratio. So: 12 Ohm speaker and 16 Ohm-tubeamp should be ok,  8 Ohm speakers with 16 Ohm tubeamp is casually possible but risky (!!!) and 4 Ohm speakers with a 16 Ohm-tubeamp will destroy the amp, and too to run (crank) the amp without speakers will destroy it. And too never connect speakers with higher impedance than the output-impedance to a tubeamp! [the three no-gos with tube-amps, what matters impedance-(mis)match]
 

What you said is valid only for most modern, common home- & car-solidstateamps, there, in reasonable ranges (usually 1:4), speakers with more Ohm can be connected. Independent of the question of damaging the equipment, purely soundwise, one should consider that all the filters in an amp are designed for a specific voltage and when this one changes because of not-exactly-matched impedances, too the working-range & the application-area of the filters change. With common home-&car-applications, this may or may not end in good sound, but specially in the space of FR (flat range)-applications, it is selfexplaining that this is absolutely contra-indicated.

But even with solidstate-amps, what you say is not a rule: Some have to be treated like tubeamps, the Hellborg power amp for example, others demand identic or permit only slightly higher impedances (1:2), like the already mentioned class-d-guitaramp 'SeymourDuncan pro stage 170' (it's made for 4 Ohm, 8 Ohm speakers are allowed to be connected, but 16 Ohm-speakers not). I read the explanations for both cases, but sorry, i simply lack the technical knowledge for to have understood & memorized anything in one read and too i do not remember where i read that, so i will refrain here from trying to explain it (please google yourself if interested). 

The best is to remind the rule (the impedances should be identic) ...and in case one wants to know if one of the exceptions is valid for the own special case, it's recommended to ask / to research.

[rvroberts]

I'm just going to put this out there - and I'm totally willing to admit it's years since I tried this - and since I've never had 2 identical speaker boxes side by side - one 4 ohm and one 16 ohm - it's always had far too much time between the 2 audio experiences............ but I'm betting you can't hear the difference.

There will be different amounts of wire on a transformer involved, so I can't prove that it's not audible - but I'd bet it's less than using a totally different amplification system all together.

Just found this video - they seem to believe there's a difference............maybe you can hear it..........no sure I can!!

 

[AMountain]

On 2/13/2021 at 11:04 PM, rvroberts said:

I'm just going to put this out there - and I'm totally willing to admit it's years since I tried this - and since I've never had 2 identical speaker boxes side by side - one 4 ohm and one 16 ohm - it's always had far too much time between the 2 audio experiences............ but I'm betting you can't hear the difference.

There will be different amounts of wire on a transformer involved, so I can't prove that it's not audible - but I'd bet it's less than using a totally different amplification system all together.

Just found this video - they seem to believe there's a difference............maybe you can hear it..........no sure I can!!

Thanks for the video.  That's a correct information (in the video): That manner with the 16 Ohm for stage-speakers is from the early days of loud rock, i.e. the use of Marshall 100Watters and their cabs as PA: With the then often very long speaker-cables, for to avoid a significant loudness-loss, it was better to use 16 Ohm.

 

When the same speaker-cab is used and only the wiring inside changed for to adjust the speaker-impedance to the amp's output-impedance (as done in the video), then it is logic that the shorter the cables between amp&speakercabs are, the less audible difference will be perceivable.

 

And with really short cables, the difference should be minimal, subtle, and at this low volume like in the video (mostly around 100db, +/- 5db) surely only technically measurable, because it's mainly only a slightly different impulse-response that most not in the audio-matter schooled ears will even not realize (specially not at this "relative bedroom-level" for Plexis).

 

16 Ohm is only interesting when the cables are that long that their own impedance surpasses 1 to 2 Ohm and the volume shall be 120 db and louder (100W Plexi-level). In that loudness-area, the guitarrist will "feel" it the most (and 16 Ohm will turn out to feel - respond - better). But that was not the volume they used in the video for their test. 100 db a 1Watt-tubeamp can easily reach and the volume in the video did not pass the 105 db. A Plexi is still sleeping at that volume (as the Greenbacks too)....  IMHO: Really, i do not buy a Plexi for to play it on 3 or 4 with the eq on ~5 +/- 2.

 

(Surely not a general rule, but) It may well be that the lower the volume, the more agradable (more complete, organic, or 'together' as they say in the video) a less high impedance sounds - that will depend the single amp's as too the single speaker's characteristics (!) and too the of the pickups, the entire combination -: At that low volume, the impulse-resistance or -strength isn't really a predominant audio-factor. So it may for example well be that an amp like the in the video used Matchless-combi (4 Ohm pre-installed by the brand) sounds better this way as long it is not fully cranked and when fully cranked (so-called 'british-setting'), it will turn out that not few guitarrists will prefer the 16 Ohm-wiring and -connection.

[ossianott]

I'm using my quilter bassblock 800 together with my stomp to power my 4x12 with v30 speakers in it, my cab is 8 ohm so I have to be careful not to fry it (it's extremely loud), but the bb800 delivers 225w at 16ohms. It has line in on the back which bypasses all EQs in front, straight wire to the amp section so all shaping happens in the stomp just as I like. The class D amp is very neutral in its sound using the line in. I have not tried plugging a guitar into the front of it but the front shaping EQ is specifically made with bassists in mind which is my main instrent with the band. the quilter stuff is of very high regard for instrumentalists.

 

Mine sound very good with the 4x12, melts my face with the rectifier and soldano