Castle Flanger Schematic

[52 Bill]

I have a Castle rackmount Flanger in for repair. Passes signal but there is a problem with the sweep. Some kind of glitch that causes the delayed signal to distort at the end of the waveform.

I've searched the web for info on this unit and can't find anything other than this was made sometime in the 80's and that Castle is long gone.

Does anyone here have any info or a schematic for this thing? If not, I'll have to try and reverse engineer it.

[cjlectronics]

I've seen this in other Flangers. The BBD was the problem. It was distorting the delayed signal and was more apparent as the signal fades out.

Sometimes just a tweak of the BBD bias and offset pots will get rid of the distortion as well.

Let us know what you find out.

CJ

[Mark Hammer]

Um, this is going to sound dumb, but do you by any chance mean the Castle Phaser? I am unaware that Castle had ever produced anything other than a couple of excellent phasers. Not that I have a schematic for it, but properly identifying the actual technology might be a good start to figuring out what to look for.

I know there are pictures of the phaser board at modezero.com, so perhaps staring at those might give some folks here a bit of a start on what to recommend.

[52 Bill]

Um, this is going to sound dumb, but do you by any chance mean the Castle Phaser? I am unaware that Castle had ever produced anything other than a couple of excellent phasers. Not that I have a schematic for it, but properly identifying the actual technology might be a good start to figuring out what to look for.

No, this is a Flanger. Single rack space, same off white color as the phasers and same logos/graphics. Yeah, I've seen the phaser photos and reviews on line, but like I said nothing on the Flanger.

I haven't spent too much time on this one yet, but it has some fairly sophisticated features. I've been researching the chips in the circuit, and have just found spec sheets on the SSM chips. The rest of the chips are fairly typical stuff, op-amps, compander, c-mos switch, etc.

[Mark Hammer]

Hmmm. Interesting. They made a great phaser. I'd be curious to know what sorts of features were incorporated in a flanger by those same folks.

Just out of curiosity, what SSM chips were included? I'm guessing they might be 2040 chips?

[52 Bill]

Hmmm. Interesting. They made a great phaser. I'd be curious to know what sorts of features were incorporated in a flanger by those same folks.

Just out of curiosity, what SSM chips were included? I'm guessing they might be 2040 chips?

Mark: I haven't had much time to spend on the research of this, but I think you are right about the SSM2040 chips. I will open it up later and let you know what's inside.

[Mark Hammer]

The castle products were made when the SSM2040s were actually available and reasonably priced (heck, I bought 5 of them from a guy in Dallas for $10 at that time!). Wouldn't surprise me if they were used for filter sections.

[52 Bill]

Mark: I was wrong about the SSM2040 chips, it uses 2-SSM2044's. Here is a list of all the IC's in the unit.

1-LM337
1-LM317
2-R5106
1-SSM2031
2-SSM2044
1-NE572
3-LM324
1-CA3080
1-4027
1-4066
5-TL072

I have posted photos of the front, back and circuit board in my folder at ampix.

[Mark Hammer]

Wow! That is a really interesting complement of chips, and what seems to be as advanced a flanger design as one is likely to ever see in the analog domain. Is this a stereo design or does it have dual oscillators or something like that? Having one NE572 suggests a mono output, but having a pair of 256-stage BBDs and a pair of SSM2044 4-pole lowpass filters suggests the possibility of two semi-independent delay paths. There is also the possibility that the device does "through-zero" flanging with one R5106 set for fixed delay.

Having an SSM2031 onboard also suggests that Castle was using a tracking filter to optimize the bandwidth/noise tradeoff. In other words, the LFO drives the SSM2031 and the SSM2044 chips at the same time. As the clock frequency goes up, so does the cutoff point of the lowpass filters. The old MXR analog delay did a similar kind of trick, except it accomplished it by dividing down the clock pulse to produce a switched-resistance variable filter, using CMOS switches. Here, I assume the circuit uses voltage-to-current convertors to feed the SSM2044s and vary their cutoff frequency.

The more I hear about this unit, the more it intrigues me.

[52 Bill]

...having a pair of 256-stage BBDs and a pair of SSM2044 4-pole lowpass filters suggests the possibility of two semi-independent delay paths.

Yes, there is a front panel switch that selects delay I or II or I & II.

As far as I can tell so far, mono signal path, a jack to allow outboard voltage control of sweep speed (?).

[52 Bill]

It's Fixed...

Ok, I put this on the bench and went through all of the voltages, everything seemed within reason. Started scoping waveforms at different points looking for problems, again everything seemed reasonable. Controls changed freq. of osc. etc.

While scoping the low freq. osc. chip, I had forgotten that the LM324 has power on pins 4 and 11. I found a perfect sine wave on pin 11 and dismissed it as ok until I looked up the pin out. Turned out to be a bad cap in the negative power supply.

This thing does have two separate delay lines, one set for a longer delay, one for a shorter delay. The front panel switch allows for short only, long only and both delays at the same time in parallel. The controls allow for full adjustment to get really nice chorus and flange effects, as well as slapback echo. All with decent frequency response (until you set for longer delay times).

Mark, before I button this thing up, is there anything you'd like to know about? If you have any questions, I'd be glad to try and answer them for you about this one.

[Mark Hammer]

Thanks for that kind offer.

1) Are they BOTH R5106 chips or is one different than the other? Seems to me that a 256-stage BBD is not exactly God's gift to slapback or chorussing, even though it helps achieve the short delays needed for flanging.

2) Any possibility of some pix? I have not found anything on-line and I imagine many folks would be every bit as interested as myself to see this puppy, and have some sense of its feature set. m If you could do any board shots, that would be heavenly.

3) Failing pix, could you describe the control features?

[52 Bill]

1) Are they BOTH R5106 chips or is one different than the other? Seems to me that a 256-stage BBD is not exactly God's gift to slapback or chorussing, even though it helps achieve the short delays needed for flanging.

They are both the same, but they are set for different delay times.

2) Any possibility of some pix? I have not found anything on-line and I imagine many folks would be every bit as interested as myself to see this puppy, and have some sense of its feature set. m If you could do any board shots, that would be heavenly.

I had mentioned before, that I had posted some photos in my folder (52 Bill) at Ampix. There is a front panel, back panel and a circuit board shot. Take a look and let me know if there is something else you want to see.

Oh, and by the way in an earlier post I made a mistake on the chip set list, there are 4-TL072 and 1-TL071, not 5-TL072s.

[Mark Hammer]

Just looked at them. Thanks a million for that. Thanks for directing my attention to the Ampix gallery too. Hadn't looked there before. Shame on me!

[Zalmo]

Um, this is going to sound dumb, but do you by any chance mean the Castle Phaser? I am unaware that Castle had ever produced anything other than a couple of excellent phasers. Not that I have a schematic for it, but properly identifying the actual technology might be a good start to figuring out what to look for.

I know there are pictures of the phaser board at modezero.com, so perhaps staring at those might give some folks here a bit of a start on what to recommend.

I have a Castle Echo Chorus unit, also a rack job.