Space Echo lots of noise in signal

[iamthekey]

Hey guys

I was wondering if someone could please help me diagnose a lot of noise coming from a Space Echo 201 I have

I recently bought it on ebay and it worked great at first. Lately, I've noticed a lot of noise from it. I serviced it by cleaning the heads, changing the tape, de-maging the heads, and changing the bearing. This solved the excessive wow and flutter, but the noise is still there.

The noise is affected by the EQ controls, especially the treble. It also seems to change in character with the Repeat Rate control, and gets louder with the Echo Volume control. So it must be early on in the circuit.

Here is a sample of the noise and how the space echo sounds: I have the signal processed with an amp sim (I apologize for the sloppy playing)

https://soundcloud.com/thestammer/te...-noise/s-dcPoo

You can hear me turn on the echo, mess with the tone control, play soft, then loud, then i just mess around for a sec.

Honestly, without the amp sim the noise is barely even noticeable. However, even clean tones will make the noise become extremely audible, and I usually like to overdrive the amp just a bit for the tones I am after.

Could this be an electrical hum problem? I have everything going into a furman power conditioner. I have the space echo as far away from my other equipment as possible.

Any advice would be helpful. Or is this considered a normal amount of noise from a real space echo?

this is it without any amp sim or guitar cab:

https://soundcloud.com/thestammer/te...mp-sim/s-eVC9N

where admittedly the noise isn't an issue. But since Im trying to record with it... would like to reamp it with a real amp, when the noise comes back like with the amp sim.

[beatnik]

That amount of noise doesn't seem right

Do you have noise also on the dry signal ? if you turn the echo level pot does the noise go away ?

increasing the treble control would make the noise increase that's perfectly normal as you are increasing the noise frequencies as well

I got a 301 on the bench right now that i'm struggling with. Different kind of noise, got a hum from one of the heads

[oc disorder]

Greetings Iamthekey (well hi or hello seemed inappropriate) and welcome to the forum.

I'm finding it a bit hard to completely visualise your set up.
I'm also guessing you don't have a lot of experience with tape echo units although
you a following the correct procedures (clean & de-mag heads etc).
They do produce noise but usually the guitar signal is far enough "above it" to hide the hiss.
Check out an old English Wem Copicat sometime for an extreme noisy example !!
The treble control will understandably increase the volume of the noise as a bass control
can sometimes increase hum.

I'll attempt to draw the signal path as I understand it, in text.

|Guitar|>|Space Echo|>|amp sim|>|Amplifier to recorder = NOISE

|Guitar|>|Space Echo|>|Amplifier to recorder = NOT AS MUCH NOISE

What I have difficulty in understanding - is the amp sim a standalone unit?

Or is it part of a recording package or built into the amp ?

Listening to your sound clips I was wondering if the amp sim has some kind of AGC
(automatic gain control) which subtly "pumps up" the gaps exposing the hiss.

Otherwise some mismatch of impedance which is exacerbating this.

A bit more clear detail is required to properly analyse the problem.

[iamthekey]

Hey! Thanks for the replies

The 'echo volume' control does makes the noise louder the louder I have the echos set. However, its still very loud even when turned all the way to the left (dry signal only) The 'echo normal' toggle switch has no effect on the noise.

The signal chain is like this:

|Guitar|>|Space Echo|>|DI to recorder interface

The amp sim is just put on top with software. It sounds the same through an amp in person, tho. I just recorded it that way for simplicity's sake.

Hmm impedence? I have a preamp with different impedance settings but it didnt have any effect.

The amp sim can be made more tolerable with the noise if a very clean tone is used... however thats not the tone Im looking for with recording and also I dont think the slightly crunch tone should have so much noise on a properly operating space echo.. it was always noisy but recently it got waayy noisier.

[oc disorder]

Well I can think of 2 things to check out.
One is to determine if the 201 has a noisy component or if it's purely tape hiss.
I'm not familiar with the 201 but stopping the motor or removing the tape should do it.
There's a reference post down below called "Tapes for space echo" with some good tips.
Doing the above makes the 201 just a pre-amp but by turning up the delay the circuitry from the heads should be silent without the tape.
There should be no noticeable hiss.

Two re the impedance this is matching in your case um 201-OUT|DI-IN~DI-OUT|SOUNDCARD INTERFACE IN|

Can you take a signal out from the LINE OUT (not the reduced "to guitar amp input" output) and straight into the line in of the soundcard
rather than the Mic/guitar input?

A line patch point would be better in the sound card interface.

I'll go look up the ins and outs of the 201. The sensitivity and impedance ... well specs of both the DI and the soundcard interface would help.

EDIT: I presume you have the service manual. Detailed info about mechanical alignment bias adjust etc.
http://bmamps.com/Schematics/Roland/...e%20Manual.pdf

OK

I see they only have the one output. It comes out at line level but you can attenuate it with a switch.

Unfortunately I have never worked on one so hopefully someone who has will notice your post.

[beatnik]

if there is noise also with the echo level control turned all the way down, then it must be coming from either the input or output amplifier section. also a bad filtering on the power supply can make the unit noisy.

best thing to do would be tracing the circuit with an oscilloscope or if you don't have access to that just build a simple audio probe, follow the circuit from the input and find where the noise build up.

you can do the testing with nothing connected on input and output, so you also exclude potential problems from your guitar signal or the amp simulator

[iamthekey]

Hey. Yeah, its not tape hiss, still did it with the tape removed. Going into the line in on the interface did not help with the hiss either.


Unfortunately after taking the tape off the heads to check, upon restoring the tape to the playheads the space echo doesn't make any noise now.... the input light on the VU will not 'bounce' when a guitar is played into it, there is no more noise but also there is no signal coming out from the echo at all. This happened from time to time before but simply turning it off and back on would usually fix it. Its been a few days now and it seems to be dead.....

I will probably have to take it to a repair guy at this point unless there are ideas. The lights for VU and power indictator turn on but that is all.

[km6xz]

There are a couple things at play here. Unless the output amp in the 201 is noisier than usual, they all have poor signal to noise ratio. That is not really as much a problem as might be assumed, higher noise items in the signal chain have to go last in the chain so it is not amplified by all subsequent stages. The amp simulator does what a high gain amp does, multiplies the signal+noise by 200 times or or more so any noise present at the output of the 201 will become much louder after going through the amp simulator.
Second problem is as with any tape system record level, eq, bias and alignment, and repro gain, eq and alignment must be right on for a reasonable signal level recovered from the tape repro heads. Any decrease in recovery signal means one has to increase the post gain to get usable signal that starts out being of poor signal to noise ratio unless the record and repro sections are properly set up. Big pro stable analog decks had to be adjusted for all these conditions for every single track every time a tape was mounted in a recording studio. It was a normal process every day, sometimes several times a day. The process was required to get the best possible signal to noise ratio, lowest noise floor. Evey space echo I have tested was out of adjustment for the tape that was used on it. Cart tape is not made anymore so any replacements are using reel tape which is usually high bias, and also has lube on only one side so the tape does not wear out rubbing against the deck mechancials. Cart tape is low bias tape and designed to slide into a hub of a cart since there is only one reel on a radio cart deck. It had to have lube embedded into the facing and backing of the tape to do that without binding on other wraps of tape. Using high bias tape would mean poor signal to noise ratio and poor high frequency response unless the adjustments and bias levels were set up. Sometimes that meant increasing bias oscillator output range.
Since yours has another problem hopefully the tech knows about tape decks. If he is 50 years old or old he probably does.