Hiss/Noise only in the FX Loop (Friedman Runt)?

William Williamson

So I've got a Friedman Runt 20 which overall is a fantastic amp, but I've found that as soon as I complete the FX loop there's an audible increase in the noise floor. I've tried this with different pedals (and different power supplies including isolated), going straight from send-return with pedalboard jumper cables, curly cables, shielded cables with no difference. 

There IS a difference if I drape the cables over the head, wherein there's definitely interference/noise from the amp - this is a flat set of noise unaffected by preamp EQ (even unplugging the pre-amp input makes no difference).

Is this just the way that FX Loops work (that is, it is to be expected to have a higher noise floor), is there something I need to bear in mind for the cables/etc. or is there something wrong with the amp? It's not terrible, but it definitely there - and it goes away as soon as I disconnect the FX loop, even if I include those pedals in my front-end signal chain.

Cabicular

You can cause earth loops which normally cause Hum and can be broken with an isolator (like a lehle p split)
hiss can be attentuation
the problem with FX loops is that they are designed for short run cables, so running long cables can cause issues
a buffer can often help
smarter people will be along with more information shortly

ICBM

A properly-designed FX loop won't add noticeable noise, and will handle any sensible length of cable.

Many amps don't have properly-designed loops.

olafgarten

I think the FX Loop in this is buffered, or at least it's meant to be so the cable length shouldn't be a problem. 

Bellycaster

Cabicular said:

You can cause earth loops which normally cause Hum and can be broken with an isolator (like a lehle p split)
hiss can be attentuation
the problem with FX loops is that they are designed for short run cables, so running long cables can cause issues
a buffer can often help
smarter people will be along with more information shortly

I really don't get this bit @Cabicular although I'm not saying your wrong, most people have their pedalboards away from the amp 10 - 20 feet sometimes, so a longish cable run is required, why would they be designed like this?

ICBM

Bellycaster said:

I really don't get this bit @Cabicular although I'm not saying your wrong, most people have their pedalboards away from the amp 10 - 20 feet sometimes, so a longish cable run is required, why would they be designed like this?

Don't know, ask Marshall why they made the Jubilee one like that!

Or ask Soldano why the SLO loop is too early in the circuit to put the effects properly after the preamp distortion.

Or Mesa why their parallel loop is so crude that you can't use a digital effect with any latency on the dry signal path, or any effect with a phase reversal in it, in the loop without causing severe tone suck.

The only conclusion I can come to is that many amp designers just don't understand FX loops.

Or you could have a loop like the one Fender use in the Hotrods, or Marshall use in the 2203 reissue, or one of the aftermarket kits you can get, all of which work so well you can't even tell they're on if there's nothing in the loop.

William Williamson

How short should the cable be? Friedman Amps have responded saying the FX Loop is always engaged, even without a cable connected - I'm still not sure if this (that is, a little more noise) is something I should live with, or if I'm doing something wrong. It's not interference, it's not hum from the power transformer. Should I look at shielded cables?

Cabicular

Bellycaster said:

Cabicular said:

You can cause earth loops which normally cause Hum and can be broken with an isolator (like a lehle p split)
hiss can be attentuation
the problem with FX loops is that they are designed for short run cables, so running long cables can cause issues
a buffer can often help
smarter people will be along with more information shortly

I really don't get this bit @Cabicular although I'm not saying your wrong, most people have their pedalboards away from the amp 10 - 20 feet sometimes, so a longish cable run is required, why would they be designed like this?

Designed to be racked during the Bradshaw refrigerator sized rig days. They are a relatively recent phenomenon and they were originally derived from studio based rackmount fx processors.
In my day people didn't have massive pedal boards on the the floor. So they only had to cope with patch cables from other rack FX. It's probably all different now I'm a bit a dinosaur but when I'm trouble shooting fx loops this is where I start

ICBM

William Williamson said:

How short should the cable be? Friedman Amps have responded saying the FX Loop is always engaged, even without a cable connected - I'm still not sure if this (that is, a little more noise) is something I should live with, or if I'm doing something wrong. It's not interference, it's not hum from the power transformer. Should I look at shielded cables?

All standard instrument cables are shielded. If all the FX loop does is break the signal path - with the send and return stages always engaged - then connecting a patch cable in it should make no difference. If it does, I would check the grounding of the jacks.

William Williamson

Thanks! cable jacks, or power jacks?

ICBM

On the amp.

Bellycaster

ICBM said:

Bellycaster said:

I really don't get this bit @Cabicular although I'm not saying your wrong, most people have their pedalboards away from the amp 10 - 20 feet sometimes, so a longish cable run is required, why would they be designed like this?

Don't know, ask Marshall why they made the Jubilee one like that!

Or ask Soldano why the SLO loop is too early in the circuit to put the effects properly after the preamp distortion.

Or Mesa why their parallel loop is so crude that you can't use a digital effect with any latency on the dry signal path, or any effect with a phase reversal in it, in the loop without causing severe tone suck.

The only conclusion I can come to is that many amp designers just don't understand FX loops.

Or you could have a loop like the one Fender use in the Hotrods, or Marshall use in the 2203 reissue, or one of the aftermarket kits you can get, all of which work so well you can't even tell they're on if there's nothing in the loop.

@ICBM ;

Sorry kept meaning to come back to this thread.

I did use the loop once on my 5:50 Express and it didn't seem too bad, although it was at lowish volume it didn't cause a volume increase or drop, tone stayed reasonably in tact. Can't speak for all Mesa Amps though.

Can't speak for the other amps but I trust your knowledge of them, it's weird isn't it with builders as regarded as Soldano having crap loops and then lower priced amps like Hotrods getting it right. No wonder I get headache choosing gear

ICBM

Bellycaster said:

I did use the loop once on my 5:50 Express and it didn't seem too bad, although it was at lowish volume it didn't cause a volume increase or drop, tone stayed reasonably in tact. Can't speak for all Mesa Amps though.

That's because the Express was the first of the more recent Mesas to go back to a simple series FX loop, which is much better. They've now changed some of the flagship models such as the new Dual Rectifiers as well.

Bellycaster

ICBM said:

Bellycaster said:

I did use the loop once on my 5:50 Express and it didn't seem too bad, although it was at lowish volume it didn't cause a volume increase or drop, tone stayed reasonably in tact. Can't speak for all Mesa Amps though.

That's because the Express was the first of the more recent Mesas to go back to a simple series FX loop, which is much better. They've now changed some of the flagship models such as the new Dual Rectifiers as well.

Let's hope other amp manufacturers learn from them

ICBM

Bellycaster said:

Let's hope other amp manufacturers learn from them

Indeed. Apparently Mesa were actually responding to user complaints about the parallel loop, so we can live in hope…

The problem is not with parallel loops as such, but the way Mesa implemented theirs. A well-designed parallel loop which goes to truly 100% effect mix when you turn the control fully up effectively becomes a series loop anyway, and if it's properly buffered and mixed then no signal leaks back past the loop… both were things Mesa failed to do!

I really don't understand why it seems to be such a difficult concept for many amp designers, but the evidence is that it is.

Bellycaster

ICBM said:

Bellycaster said:

Let's hope other amp manufacturers learn from them

Indeed. Apparently Mesa were actually responding to user complaints about the parallel loop, so we can live in hope…

The problem is not with parallel loops as such, but the way Mesa implemented theirs. A well-designed parallel loop which goes to truly 100% effect mix when you turn the control fully up effectively becomes a series loop anyway, and if it's properly buffered and mixed then no signal leaks back past the loop… both were things Mesa failed to do!

I really don't understand why it seems to be such a difficult concept for many amp designers, but the evidence is that it is.

The Bogner FX Loop was a real learning curve and I think in the end I still didn't quite understand the true meaning of Parallel Loop, the GF has the option of both, in Series the FX Mix control just works as a Volume control and I found I just preferred the Parallel, although I don't know if it's 100% Wet even when the FX Mix is turned up to full if that makes sense.

I never use the FX Loop for gigs as I get all OD from pedals for that, although it's good to have one if using the amp's overdrive at home.

William Williamson

So, Dave Friedman has suggested it might be a preamp tube (which is probably my next port of call) but after more testing, I've come across something. One of the cables I was using for my FX loop appears to be acting as an aerial: quite apart from transformer hum, I can hear it pick up crackle and hiss when I move it around. It's a long old planet waves cable - so I guess I need to replace it - any ideas for some high quality, shielded instrument cables with right-angled jacks?

Additionally, the delay pedal I use (DM-2w) adds a bunch of noise with the 'echo' dial up even if I'm not playing any notes, and the echoes themselves are quite fuzzy which sounds a bit like noise at low volume.

Additionally, I tried turning down the presence a little (which cut some of the highs).

Solution 1 
I'm thinking of getting a nice pair of cables to use in my FX loop (ideas appreciated - so far I have a couple of short curly cables, two long stagg right-angled cables and this scratchy planet waves cable. 

Solution 2
I'm thinking if that doesn't work, to get myself an ISP Decimator G-string or Boss NS-2 to run in a four cable configuration - the amp is almost totally silent even gunned if the FX loop and preamp are out of the equation. The only thing that 'worries' me is that I'm not really a super heavy high-gain player, and I don't know if it will affect dynamics especially on something like the delay...

Deijavoo

Solution 1:

KaBL or http://www.bedfordguitars.com/

ICBM

Cables: Kabl (@RobDavies on here). He'll make you anything you want to spec.

Planet Waves cables are junk - although hiss is a new fault I haven't come across yet… usually they sound muffled, drop in volume or just stop working.

Modulus_Amps

Are there any trimmers for the effects loop, send level/return level?

If the noise floor is ok without anything plugged in then it is the interaction of your cables/pedal with the amp that is causing the noise

Are you using a power supply or batteries with the pedals? some power supplies cause noise to try batteries to see if the noise goes away.
Are you using the same power supply for the pre amp effects as the effects loop?
crap cables need replaced, if they make any sound when moving they belong in the bin.

Effects loop design has so many options available, send level, return level, parralell/series, polarity, switchable, additional tone shaping..... but most guitarist just want a simple send return to work with a few pedals, from what I know of the Friedman effects loop, that is what they are set up to do.

Neckwringer

I make and personally use these Sommer leads into my FPRA loop with no issue's.



I have a Fender curly lead that when inserted into my Quilter SS amp can be played as an instument

in the percussive style.