Home » VintageKustom.com » Repairing Kustom Amps » K250 Adding an Effects Loop ( . . . .anybody ever tried this?)
K250 Adding an Effects Loop [message #25117] Sat, 25 June 2016 06:46 Go to next message
LeeNails
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Been playing my K250 quite a bit lately and was considering taking it out to gig. I want to run an Orange Bax Bangeetar pedal for my Gain sounds, but have heard they work better through the effects loop . . . which the K250 hasn't got. Have any of you ever tried adding an effects loop to the K250?
Re: K250 Adding an Effects Loop [message #25120 is a reply to message #25117] Sun, 26 June 2016 06:14 Go to previous messageGo to next message
stevem is currently offline  stevem
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The amp in a way already has a loop.

Pull the signal out of the tape output jack and then use the power module output jack as the input , and yes it will work both ways, as in a output or a input jack!

The only issue may be that the signal off of the tape out jack can be quite hot ( like up to 3 volts ) dependant on how loud you play the amp.

You could deal with this two ways, one would be to pad it down with one of those Mic transformers that step a low impeadance mic up to high, or you could get hold of a 1 meg ohm pot, stuff it in a small project box and wire it up as a simple volume control.
If you have a unsed volume pedal this would be the place to use it!

You should first try out just going straight in with your out board gear you have as you might find that that works just as well.
What I use to do for a while since I has one was use my stomp box chorus and it's stereo output to split my signal from my guitar off which would then feed my other stomp boxes and I would then take that output and feed it into the other unsed channel of my K250.

The only thing you need to watch out for when doing this with any solid state amp is to not drive its preamp with too much signal level or you will pop the first semiconductor your signal get applyed to , be it a transistor or a IC chip!

To avoide this mess if you are using a stomp box for distorted lead tones , that lead volume should not be all that much louder then what your plugged straight in to the amp volume level is.
This means using your guitars volume control or a volume pedal to back down your signal level for backing playing.

The metal face amps are a tad more forgiving of too high a input signal level , but do not try pushing things too far with all of the early model Kustoms or you will be driving it somewhere to get fixed before you know it!

Another thing to keep in mind with any solid state amp if you are using stomp boxes in front of it or thru its effects loop section is to never apply signal with the amp off, the amp must be on first to avoide once again popping things!

Enjoy your K250 and help it to continue to live a long life!

[Updated on: Sun, 26 June 2016 06:18]

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Re: K250 Adding an Effects Loop [message #25121 is a reply to message #25117] Mon, 27 June 2016 12:28 Go to previous messageGo to next message
chicagobill
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Registered: April 2003
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C'mon Steve, you gotta stop posting at 3 am, that will not work. The tape output jack is fed from the power amp output and the module output is basically just another input to the power amp. Hooking anything between those two jacks will just create a massive feedback loop.

It might be possible to add loop jacks at the input of the power amp, but as Steve mentioned the signal will be high there and may not work well with all FX without some sort of signal reduction.
Re: K250 Adding an Effects Loop [message #25122 is a reply to message #25117] Mon, 27 June 2016 14:24 Go to previous messageGo to next message
stevem is currently offline  stevem
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yup, your right, my thoughts where misguided, by there at the input to the power amp would be the place to break the circuit open and it would be easy to go with a stereo jack to replace the one there and then you could run both the send and return off that same jack.
Re: K250 Adding an Effects Loop [message #25123 is a reply to message #25122] Mon, 27 June 2016 21:43 Go to previous messageGo to next message
pleat is currently offline  pleat
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Using a switchcraft 12B stereo jack to do a combination send and return, you would have to use the effects loop all the time. if nothing was plugged into the jack then signal path would be stopped. Using a Switchcraft 14B closed stereo jack, if not used the signal would run as normal. Plug in a stereo send return cable then that would route the signal to the effect and back to the power amp. If it were me, I'd install two switchcraft 12A switching jacks.
pleat
Re: K250 Adding an Effects Loop [message #25126 is a reply to message #25117] Tue, 28 June 2016 06:40 Go to previous messageGo to next message
stevem is currently offline  stevem
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I messed around with one of my 250's last night along with a rack mount digital echo I have.
This unit can be jacked straight into on the ftont , or with rear jacks effects loop style.

I took the signal off of the module output Jack and returned the signal into the amps second channel .
The result was not good as the signal was too hot coming into the echo and of the wrong impeadance .
It would seem that the best way to do what the original poster of this thread wants to do would be to Y out of his guitar , into what it was he would have added into a effects loop and then just feed that into the Channel of the amp.

That all being said it would not take much to make up a little buffer circuit from a dirt cheap 741 IC chip to be able to use the module output I would think?
Re: K250 Adding an Effects Loop [message #25131 is a reply to message #25117] Tue, 28 June 2016 08:32 Go to previous messageGo to next message
LeeNails
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What I wanted to do was install 2 jacks . . an OUT TO EFFECT, and a BACK IN. I can't go back in using one of the front panel channel inputs because I'd already be using both of those to A/B my Rhythm and Solo sounds.
Re: K250 Adding an Effects Loop [message #25213 is a reply to message #25131] Thu, 14 July 2016 05:18 Go to previous messageGo to next message
LeeNails
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Registered: June 2016
Location: earth
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UPDATE:


Well, the sad fact is, it doesn't look like the K250 is going to work as a stage amp for me. The problem is, I can't hear the thing unless it's cranked . .and then it's TOO loud! I'd forgotten, but I learned about this phenomenon decades ago as a bass player. I noticed that tube amps always seemed to sound louder on stage no matter how you cranked the solid state amp up. It must be something to do with the shape of their sound waves. When I use my newer Kustom V100 tube twin Defender, I can get a great sound and hear it fine. It seems to sorta fill the air up with its' sound. I had the same experience with my other tube amps, Vox, Orange, Ampeg and Fender. My other guitarist has a little 1x12 Fender Super 60 (red knob) and she was blowing my doors off with it versus the K250. If I stood right in front of the K250 it was blaring loud, but it didn't fill the room.

As I mentioned, I was using my new Tonebone Hot British pedal for my Gain. When I cut off the Tonebone and ran the K250 clean for our song "Child of the Night" it DID sound loud enough in the room. Funny.

For now, I'm going back to the Kustom Defender V100. But I still need a clean sound, and it's too much of a hassle to switch the EQ settings back and forth mid song. The K250 is wayyyy too much amp to drag around to gigs ALONG with the Defender V100, so I guess I need a smaller 2nd amp.

I just bought a Kustom Sidewinder combo amp that needs some fixing. It's shipping in from WI soon. With luck I can get it running and put that up With the Defender for my stage arsenal. I think the Tonebone might be on its' way back to GC. LOL

Anyway, thanks for trying to help. Onward and upward!
Re: K250 Adding an Effects Loop [message #25214 is a reply to message #25117] Thu, 14 July 2016 06:17 Go to previous messageGo to next message
stevem is currently offline  stevem
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What speakers are you playing the 250 thru?

What's likely taking place is that you do not have enough mids.

These Amps can / have push a lot more top and bottom then a tube amp ,and with there greater than 100 watts of clean power you can push bottom that a tube amp can't, but bottom end even on six string guitar you feel more than hear, so that leave you with little mids and too much top.

I would suggest backing down on the volume that you run it at and add mids , or cut down on the top and bottom.

Our ears perceive mids as being some 70 percent of the audio frequency range we can hear, it's like listening to a song on a MP3 where 85% of what should be there content wise is not compared to listening to a CD, or even better old vinyl !
Re: K250 Adding an Effects Loop [message #25216 is a reply to message #25214] Thu, 14 July 2016 08:02 Go to previous messageGo to next message
LeeNails
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Registered: June 2016
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I appreciate the helpful hints, but I really think the problem is the inherent characteristics of a solid state amp, especially a vintage one. As I said, it's not the first time I've noticed this phenomenon. Solid state amps just seem very 'directional' and the volume doesn't 'bloom' until you get farther away from them. I was using the typical 2x15 Jensen loaded Kustom cab that came with the head. That cab is (I believe) an 8 ohm cab, the dpeakers each being 16 ohms, so it was probably giving me around 75 watts RMS. I noticed when I was playing bass through it on the break, that it couldn't compete with the Ampeg system at all. LOL.
Still, 75 solid state RMS watts should sound damn loud. . . and it DID if you stood right in front of it, or ten feet in front of it. I played with the mids on the amp, and also the WIDE parameters of kids on the Tonebone, but it didn't help. I could not get it loud enough to hear without being TOO loud. Once I switched back to the tube amp, the problem entirely evaporated.

As I said, I didn't have the same problem when running the amp clean, and it might be possible that installing an effects loop and running the pedal (which has a 12AX7 tube) into that would help, but I kinda doubt it. My plan as of now is to see if I can get a good Clean tone on the Kustom Defender V100 and use the Tonebone for Gain, since I cannot simply switch between Clean and Gain on the amp without re-EQing it. Failing that. . . .as I rather expect to, frankly, I DO have that Kustom Sidewinder on its' way, so I'll just use that with the Defender if I can get the Sidewinder running (the Reverb ain't working and it's noisy as hell if a guitar's not plugged into the input).

My plan for the Kustom 250 is to hang onto it and use it for bass. I sometimes still play bass live. I'll likely try to get that cab to 4 ohms, switching out the speakers if I need to. They expected you to use TWO 2x15 cabs to get full power, but I don't want to have to drag two around to gigs. . . although I do HAVE two Kustom 2x15 cabs.

The Defender V100 is the best sounding Kustom amp I've ever heard. . .I just wish they'd put it in a Tuck 'n' Roll cab.
LOL. It's an odd design, poking out the top back like a Vox AC30, and it's TALL inside. Not very easy to make a Tuck 'n' Roll style cab for, or I WOULD.
Re: K250 Adding an Effects Loop [message #25217 is a reply to message #25117] Thu, 14 July 2016 08:10 Go to previous messageGo to next message
stevem is currently offline  stevem
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Just note that 15" drivers will tend to beam the highs !
Re: K250 Adding an Effects Loop [message #25226 is a reply to message #25217] Thu, 14 July 2016 20:21 Go to previous messageGo to next message
pleat is currently offline  pleat
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Not really sure what the other amps and cabs are, but if the other amps are open back and the Kustom 2x15 is closed back, then the 2x15 cab and amp will be more directional compared to a open back amp on stage.
I run a Kustom K50 open back on stage with a floor processor pedal and I've always had enough power to play any stage and a lot of outdoor venues. I've been accused of the amp being a 100 watt tube amp from young musicians that can't believe it's solid state and only 25 watts rms.
pleat
Re: K250 Adding an Effects Loop [message #25227 is a reply to message #25117] Thu, 14 July 2016 21:15 Go to previous messageGo to next message
LeeNails
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Registered: June 2016
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Y'know, you just may have a point there. My Kustom Defender V100 does have an open back, and the K250 2x15 is closed. However, I do seem to recall that my Ampeg tube 100 watt V-4 sounded much louder than my Peavey 400 series Bass solid state through the exact same Webb 2x15 closed back cab.
Anyways, I've got the 1x15 open back 75 watt RMS Sidewinder on the way from WI, which will be much easier to lug around than the K250 head and 2x15 cab. . .if I can get the Sidewinder running right.
Re: K250 Adding an Effects Loop [message #25228 is a reply to message #25227] Thu, 14 July 2016 22:34 Go to previous messageGo to next message
pleat is currently offline  pleat
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The sidewinder came with either a JBL D13F or the standard KEI 15". Most problems with the SS series are the white Molex connectors that connect the circuit boards to one another. They tend to corrode and make and break connections. Same issues as all the slant metal face amps.
When the amp is running correctly, it is a a great sounding and very loud amp for sure.
pleat
Re: K250 Adding an Effects Loop [message #25230 is a reply to message #25228] Fri, 15 July 2016 03:26 Go to previous messageGo to next message
LeeNails
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Registered: June 2016
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It's weird that the store says the amp is really noisy without a guitar plugged into it, but that the noise goes away when an instrument is connected. They also say that the reverb is dead. I wonder if that's a connection or if there's even a tank still in there. When I got the Kasino Little Joe, the reverb sounded crappy and weird, but it just turned out that the springs had come of their little connection hooks. Once reconnected it worked fine. The reverb on my AC15 died once, but it turned out that one of the connection wires in the tank had gotten broken. I re-soldered it, and it was fine again. I'll be sure to look at the Molex connectors. Can they be cleaned (with What?) or do I have to just replace 'em?
I've got one plexi head. . . .I think it's a bass 200 (no reverb or trem), but it's not working right yet. The K250 works like a champ, although the lights in the switches are burnt out (the former owner included at least one new bulb. . .don't know how to install it). As I said, I once owned a 2x12 Commander, wish I still owned it. I've never owned a functional plexi Kustom, but I've tried a few. I think I like the metal face amps better, though they don't have that vintage CCR look, they seem to sound better and perform better to me.
Re: K250 Adding an Effects Loop [message #25231 is a reply to message #25117] Fri, 15 July 2016 06:43 Go to previous message
stevem is currently offline  stevem
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98 % of the time just plugging the connectors in and out a few times will do the trick and get things back up and running.
Just be carefull with the 3 terminal connector on the output stage driver board as for some reason they have the little pin support on the bottom side of the board and I have had many amps where one more connector removal and reload would have failed a factory solder connection fully!
After I solder these I place some clay epoxy on the bottom of the board to support them 100 %.

Within the connectors you can squeeze down the Female portion and on the Male side if you grind a long finishing nail to a point you can expand the head of that end from its center.
Applying some synthetic grease to both pins will complete the fix.

I have fixed many of these that after 30 to 45 minutes of being played they crackled and cut out and it was due to failed solder connections at this point.

I would advise anyone with a metal face amp to pull the chassis out, unplug and flip the board over and reflow those 2 out of 3 very inportant connections, even more so if you know the amp has seen a lot of moving from road or club use!
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