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Topic: Effects through send and return comments |
George Kimery
From:
Limestone, TN, USA
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Posted 7 Apr 2020 6:37 am |
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The amp manufacturers recommend running effects through the send and return function on the amp. I have tried this with a lot of different amps and could never tell much difference until now. I recently acquired an Evans SE 200, but had not tried the effects loop until a couple of days ago. The improvement in the sound is pretty significant. I have gone back and forth a few times just to be sure and there is definatly a difference.
I have always went guitar > Black Box > volume pedal > Wet Reverb > DD- 3 delay > amp. Looking for others experienice or opinions
on this issue. |
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ajm
From:
Los Angeles
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Posted 7 Apr 2020 8:00 am
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George Kimery wrote: "The improvement in the sound is pretty significant."
Improvement? Details?
What effects are you now using in the loop? |
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George Kimery
From:
Limestone, TN, USA
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Posted 7 Apr 2020 8:19 am Effects through send and return comments
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| AJM, I'm still running the same two effects, the Wet Reverb and the DD-3. The sound is just clearer and cleaner.The only thing that sounds reasonable to me is that by using the effects loop you are getting more pure, uncolored sound from your guitar into the amp.Maybe the effects are added post EQ to keep them as pure as possible also. |
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Ian Rae
From:
Redditch, England
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Posted 7 Apr 2020 9:22 am
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To get the best out of a superior amp, its own preamp should be the first thing your guitar sees. Otherwise you are asking it to process a signal with a way more complex wave form than it's expecting. The loop is there for a reason. If you can't tell much difference with other amps, that says more about those amps than about the manner of hooking up.
_________________
Make sleeping dogs tell the truth!
Homebuilt keyless U12 7x5, Excel keyless U12 8x8, Williams keyless U12 7x8, Telonics rack and 15" cabs |
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Fred Treece
From:
California, USA
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Posted 7 Apr 2020 9:26 am Re: Effects through send and return comments
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| George Kimery wrote: |
| AJM, I'm still running the same two effects, the Wet Reverb and the DD-3. The sound is just clearer and cleaner.The only thing that sounds reasonable to me is that by using the effects loop you are getting more pure, uncolored sound from your guitar into the amp.Maybe the effects are added post EQ to keep them as pure as possible also. |
That’s what it is. The effects are basically bypassing the preamp. Your Black Box and VP should still be going straight to the amp input. |
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Dennis Detweiler
From:
Solon, Iowa, US
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Posted 7 Apr 2020 2:00 pm
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Effects before the preamp will usually dull (muddy) the tone.
_________________
1976 Birdseye U-12 MSA with Telonics 427 pickup, 1975 Birdseye U-12 MSA with Telonics X-12 pickup, Revelation preamp, Carbon Copy Delay and Hall Of Fame Reverb, Crown XLS 1002, 2- 15" Eminence Wheelhouse speakers, ShoBud Pedal, Effects Pedals. 1949 Epiphone D-8. |
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Fred Treece
From:
California, USA
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Posted 7 Apr 2020 3:35 pm
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| Depends on the effect, and it’s quality. Generally speaking, volume and tone modifiers and overdrives before the pre, ambient effects in the loop. |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 7 Apr 2020 4:46 pm
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Before putting effect units before the preamp … check that input/output impedances match well enough for comfort.
Before putting effect units in amp-loops … check that input/output signal levels loops and effect units can handle match.
And that's about it when it comes to where to insert effect units. |
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Godfrey Arthur
From:
3rd Rock
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Posted 7 Apr 2020 9:03 pm
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| Georg Sørtun wrote: |
Before putting effect units before the preamp … check that input/output impedances match well enough for comfort.
Before putting effect units in amp-loops … check that input/output signal levels loops and effect units can handle match.
And that's about it when it comes to where to insert effect units. |
Yes!
And to add to this, not every FX pedal works well in all situations. Pedal designers are always fraught with some snag they can't fix.
Finding the right pedal that works with your amp/setup/rig is the quest. If one likes a certain pedal, then finding the amp that will make the pedal work is that quest.
Short of putting the cart before the horse, if you like an amp, then find pedals that will work with it.
If you look at many pro set ups, it's complicated all because there is no one-size-fits-all scenario.
_________________
ShoBud The Pro 1
YES it's my REAL NAME!
Ezekiel 33:7 |
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Jim Pitman
From:
Waterbury Ctr. VT 05677 USA
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Posted 8 Apr 2020 12:51 am
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I second Goerge's thoughts.
Because our instrument has so many strings, our pickup have more than the usual amount of wire and are quite hi impedance for that reason. The input impedance of the amp must be high so as not to create a low pass filter. You'll find most pedals (and some amps) don't have high enough input impedance for pedal steel and will tend to attenuate the high end. |
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Dan Kelly
From:
Boston, MA
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Posted 8 Apr 2020 7:42 am
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OK Goerge and Jim... Where, or how, does one find the impedance values in question? What are the +/- tolerances between the amp and pedal imdedance values that are typically acceptable?
Update:
Empress Echosystems Delay Pedal
Input impedance: 1MΩ
Output impedance: 100Ω
THD BiValve-30 Single-Ended Class A amplifier head
Input and output impedance does not seem to be listed in the specs - looking for a schematic...
_________________
blah, blah, blah.
Hey You Kids! Get Off My Lawn!
blah, blah, blah. |
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Dave Mudgett
From:
Central Pennsylvania and Gallatin, Tennessee
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Posted 8 Apr 2020 8:10 am
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| Dan Kelly wrote: |
| OK Goerge and Jim... Where, or how, does one find the impedance values in question? What are the +/- tolerances between the amp and pedal imdedance values that are typically acceptable? |
OK, I'm not Georg or Jim. But a lot of pedals - not all - list the input impedance and output impedance in the specs. This might be online, or it might be in the user manual. I just picked up one of these MXR (Dunlop) pedals on a stupid deal the other day, and looking through, all the manuals for the Dunlop MXR pedals list both in the specs - e.g., https://www.jimdunlop.com/content/manuals/CSP037.pdf - the specs are near the end.
A reasonable rule-of-thumb is that the input impedance of a receiving device should be at least 10 times the value of the output impedance of the sending device. I prefer higher - think about it this way - if you like a Tele or Strat into a Fender amp, you're talking about roughly a 6 KOhm output impedance into a 1 MOhm input impedance into Input 1, or a ratio of about 167. Or using my preferred single-coil pedal steel pickup impedance of around 17.5 KOhm, that comes to about 57. Or into a Peavey amp with impedance in the roughly 350-500 KOhm range, that comes to 20 for 350 KOhm.
My take is that as long as it's above 10-20, it's probably OK. There are times when I want more, but that's what a buffer is for - and is why I keep a Freeloader in my gig bag. The input impedance can be varied from, I think, something like 100K to about 1 Meg.
I generally don't fool around with effects send and return. I prefer to run into the front of the amp, but I am conscious of the need to deal with input and output impedances. |
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Dan Kelly
From:
Boston, MA
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Posted 8 Apr 2020 9:00 am
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Thanks Dave - I am climbing up the learning curve on this and appreciate the help.
It seems that the input and output impedance of my amp is not published. However, I found a limited amount of discussion about those values at the "Gear Page" forum. This lead me to e-mail the amp manufacturer and I am awaiting a response. I did find the schematics for the amp.
It is not my intention to hijack this thread. So, if it seems more appropriate, PM me to take this elsewhere.
_________________
blah, blah, blah.
Hey You Kids! Get Off My Lawn!
blah, blah, blah. |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 8 Apr 2020 9:16 am
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| Dan Kelly wrote: |
| Where, or how, does one find the impedance values in question? What are the +/- tolerances between the amp and pedal imdedance values that are typically acceptable? |
Usually in the documentation that comes with the (new) units, which these days more often than not can be found on-line even for older units.
"Tolerances" are a "funny thing" when it comes to impedances, so I better explain.
- One wants OUTPUT impedance to be as low as possible for effect units, preamps, buffers, etc. Below 1Kohm is quite normal, which is fine.
- The old "rule of thumb" is that the INPUT impedance should be at least 10 times higher than the OUTPUT impedance of whatever that is feeding it. Now, to get that right, using a "normal" setup with only PSG-PU, passive VP, and amp-INPUT as example…
1: the PSG-PU is about 16Kohm (typical value for a humbucker)
2: the VP is 500Kohm (typical value)
3: the amp-INPUT is 330Kohm (also a typical value)
The PSG-PU will "see" an impedance of around 200Kohm as lowest value, as the VP and amp-input are summed – no effect units. 200Kohm is better than the "rule of thumb" mentioned above, so no problem "on paper". Only that; a passive pot is not a "constant load/impedance", and cable-capacitances are adding somewhat of an unknown load in the higher frequency range.
Add a buffer in front of the VP, and the PSG-PU will only "see" that buffer's INPUT impedance – typically in the 500Kohm to 1.5Mohm range and perfectly stable, unless it is made adjustable by design. OUTPUT impedance of such a buffer is typically below 1Kohm, so the passive VP, cable and amp-INPUT that follows summed up will be plenty high enough (more than 200Kohm loading the buffer's 1Kohm).
Inserting one or more effect units before or after the VP before the amp-input, will not matter impedance-wise as long as the buffer is there for the PSG-PU to "see". All effect units I know of have INPUT-impedances in the 500Kohm to 2Mohm range, and OUTPUT impedances in the "lower than 5Kohm" range, but once several are chained up one after the other they do in fact represent a loop of their own, so better check how amplification and signal levels match up from one to the other too while you're at it.
Take away the dedicated buffer and let an effect unit take its place, the PSG-PU will only "see" that effect unit's INPUT impedance instead. As such units' INPUT impedances vary quite a bit between units – 500Kohm to 2mOHM, and up to 10Mohm in some rare cases, although the "rule of thumb" will be met just fine the impedances will explain some of why one effect unit sound better when placed before all else than another effect unit will.
Bottom line: as long as the "rule of thumb" – any INPUT at least 10 times higher impedance than whatever OUTPUT that is feeding it, all talk about "impedance mismatch" and/or "+/-imedance tolerances" is mute – on paper that is.
PSG-PUs are passive (coils) though, and sensitive to all those minute details that make up the INPUT impedance that is loading it. Deviations in that load won't harm any PU in any way, but can be heard as "sound coloring". Just knowing that simple fact can help finding "what unit works best right after the PU", and why that is.
Sorry for looong response, but backing up quite simple facts with a few details from 55+ years of hands-on experience with the subject, tends to require more than what I can put in a sentence or two. |
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Dave Mudgett
From:
Central Pennsylvania and Gallatin, Tennessee
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Posted 8 Apr 2020 10:47 am
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| Quote: |
THD BiValve-30 Single-Ended Class A amplifier head
Input and output impedance does not seem to be listed in the specs - looking for a schematic...
It seems that the input and output impedance of my amp is not published. |
I had a BiValve, sold it a few years ago. Kept the Univalve and Flexi 50, which I prefer. The output impedance of the BiValve is, more or less, whatever you set it to on the back. There is a "8 or 16 Ohm" setting and a "2 or 4 Ohm" setting. I wish they would just state what the nominal impedance is, but I assume the former is around 8 Ohms and the latter is around 4 Ohms. But impedance matching for power transfer to the speaker load is totally different than voltage signal transfer from one preamp or effect stage to another. For maximum power transfer, the load impedance should be matched to the complex conjugate of the source impedance. It's never achieved precisely in practice, but the closer you get, the better. But remember also that the impedance of transformers and speakers is highly frequency-dependent. It is only possible to get in the ballpark in practice.
I have never found a published number for the input impedance of any of the 3 THD amps I've had. But they are reputed as having a very high input impedance - I assume 1 Meg or even more - they brag about their amps' sensitivity to different pickups. So there should be no issue with transfering signal voltage to a THD amp from a pickup. But you need to worry about the loading from various pedal/effect stages. If the ratio of input impedance of any receiving pedal to output impedance of any sending pedal is not high enough, the signal can get loaded down and lose high end right there. |
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Dan Kelly
From:
Boston, MA
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Posted 8 Apr 2020 11:22 am
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WOW... Georg and Dave... Thank you. I will have to meditate on your responses for a while and let it sink in. Thank you both for the time you took to explain.
One last related question... does it make sense to ask about the effects loop's own input and output impedance of a given amp?
_________________
blah, blah, blah.
Hey You Kids! Get Off My Lawn!
blah, blah, blah. |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 8 Apr 2020 11:37 am
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| Dan Kelly wrote: |
| One last related question... does it make sense to ask about the effects loop's own input and output impedance of a given amp? |
I always check such details, but have yet to find effect loops that are not OK for what they are used for impedance-wise.
Audio levels are what really matters for those loops, as inserted effect units must be able to handle those levels without distorting and vice versa, and too much deviation between the loops and effect units' nominal levels may lead to a noisy result. |
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Dave Mudgett
From:
Central Pennsylvania and Gallatin, Tennessee
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Posted 8 Apr 2020 1:58 pm
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| Quote: |
| One last related question... does it make sense to ask about the effects loop's own input and output impedance of a given amp? |
I'd suggest asking them about that directly, since they don't discuss effects loop impedances in any of their literature, which is here - http://www.thdelectronics.com/library.html. This isn't surprising - they don't even state their amps' front-end input impedances. But I think it's safe to assume it's a pretty low-impedance out and a fairly high impedance return. But if you read carefully through the user manual, you'll see it's for line level (+4 dB) effects only. Forget about most pedals unless you want to pad the send and then re-amplify for the return.
In the BiValve technical spec manual, they do talk in some detail about the transformer-isolated line out:
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The BiValve-30 has a GREAT-sounding transformer-isolated line out on the back panel complete with an adjustable level control and a switch to choose Line- or Instrument-Level signal. The transformer used in the line out was chosen for its pickup-like impedance and tonal characteristics. Most ampliï¬ers’ line outs only work well when used to drive other power ampliï¬ers, and sound harsh and thin when plugged into the guitar input of an ampliï¬er. Not so with the THD BiValve-30. Even into the input of a Marshall 100-watt head, the BiValve-30 provides a warm, fat, tight and sweet sound that FEELS like an ampliï¬er, not like a preamp-amp rig.
The BiValve-30 can drive any speaker load from 2Ω all the way up to 16Ω. When there is no speaker plugged into the speaker jack, the amp uses its own built-in dummy load so no damage will occur, and to allow the silent use of the amp for direct recording purposes when miking a cabinet is not practical |
So they say it's "pickup-like" but again no actual impedance figures.
I picked up a 200-Watt Quilter Tone Block 201 a couple of months ago, which I've found pretty useful so far. But I'm not nuts about the more gainy sounds. I probably should try the line outs in my UniValve and Flexi 50 into the Quilter to see if I can get them to work at a more practical level for pedal steel. The issue is headroom - I only like to run amps to the edge of breakup, which doesn't really give me enough volume reserve for pedal steel with a volume pedal. My THD amps splat a bit too early for me. |
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George Kimery
From:
Limestone, TN, USA
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Posted 8 Apr 2020 3:10 pm Effects through send and return comments
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Thanks for all the participation in this post. I have enjoyed the discussion. I don't know if any of my gear's impedance and/or ohms match or not. I just know my Evans sounds better using the effects send/return function in the amp instead of from the guitar and before the amp. So I will stay with the way that sounds best.
BTW: I don't know if it's a factor or not, but I am using a Black Box which has the Freeloader built in. |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 8 Apr 2020 3:36 pm Re: Effects through send and return comments
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| George Kimery wrote: |
| BTW: I don't know if it's a factor or not, but I am using a Black Box which has the Freeloader built in. |
Is that "a freeloader circuit connected before the BB circuit" or "a Freeloader circuit connected after the BB circuit" ? And this "composite" unit is used as a buffer before anything else?
In both cases it will be kind of a "butter on fat" case that renders both the individual circuits less effective, but having the Freeloader circuit first will in my book render the BB a lot less effective than having them set up the other way round. |
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George Kimery
From:
Limestone, TN, USA
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Posted 8 Apr 2020 5:39 pm Effects through send and return comments
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I had an Evans pre-amp that was too bright for my ears. I talked to Brad Sarno and he offered several solutions
One solution was to make a special cord with a resistor built in. He said I could send it to him to do a mod like he did for John Hughey. Another suggestion was a Freeloader or a Black Box with the variable Z control. He said the Black Box is a Freeloader with a tube buffer added. I decided to go the Black Box route. It has worked out perfectly. Brad can answer your question, but I can't. |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 8 Apr 2020 10:36 pm Re: Effects through send and return comments
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| George Kimery wrote: |
| […] He said the Black Box is a Freeloader with a tube buffer added. |
OK, the BB with vary-Z circuit. That works. |
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