Posts Tagged ‘Compressor’

DOD 525 Compressor Limiter

Sunday, April 26th, 2015


What is it?
DOD 525 Compressor Limiter from the Performer series. Made in USA in early 80’s.

My first contact with any performer series boxes was with 525A Compressor and a few other i serviced a while back. At the same time someone was selling this unit for a very decent price. And since i’m quite fond of all DOD units, i just had to get it. I have not seen the original battery door on any of the performer series units yet. If the older FX-series units are prone to lose their battery doors, this series is even worse. The battery compartment is designed to hold two 9V batteries, so the covered area is way bigger than in FX-series. Which then means that the plastic clip design is even worse. There is some crude beauty in the Performer series, both inside and out. The board represents the same type of hand made mojo as the first series boards. No ground fill and everything looks, well. Hand made. What comes to the electronics, we have a CA3094 OTA based compressor that’s not too far off from any other OTA compressor of the era. The 18V operation is the thing that separates this from the most. There is an old factory schematic scan up at FIS.


The biggest weirdness is with the DC connection. Sure, the 18V requirement had to be addressed so it wouldn’t be confused with the 9V supplies  that every other pedal series wanted. But to go with 6,35mm guitar plug was probably not the greatest choice. Good thing though. The jack has about 11mm hole diameter, so swapping it for standard 2,1mm, 12mm barrel bodied jack with a switch is easy to do. Haven’t swapped the one on mine yet, but i’ve done it for a few other pedals. This series is the ultimate example of 9V vs. 18V. It may offer unwarranted hazzle to have two different voltages on your board. But..

How does it sound?
Nearly the same as most good OTA compressors out there. With exception of higher headroom, level of presence and studio quality compression. Dynamics are richer and without the knowledge of the voltage in play, there is something quite magnetic about the tone. Almost magic. Decent level of boost and sufficient controls. Yes. This unit can take on any modern compressor. Maybe the signal to noise ratio could be better, or the general noise floor lower. This is not meaning that the unit is noisy in any way. It’s just that i tried to think what would be the negative thing to mention. There is very little wrong with this compressor. If we disregard the missing battery door and the original, weird power connection, we have amazing sounding vintage effect on our hands.

DOD 280 Compressor

Sunday, March 15th, 2015


What is it?
DOD 280 Compressor. Made in USA, 1979.

Late 70’s DOD classic. This particulat unit had mean pumping sound that made it pretty much unusable. So the previous owner had it modded by me. Instead of doing something permanent and killing the heart of the tone with extensive modding, i simply solved the pumping by other means. The box itself, by appearance, would definitely make you think about MXR Dyna Compressor and its big sister, the Ross Compressor. But this assumption would be completely wrong. Even though the box layout is the same, the guts are nothing alike. Dyna and Ross both rely on the OTA, while 280 is an optical design. The schematic can be found by using any internet search engine and there are number of slightly different versions around. You should check them out for yourself, if you’re interested.

Back to the mod. Like i said, the effect was just way too steep to call it even remotely usable. The LDR simply attenuated the attack too much, even when the compression control was set at minimum. The opamp was taking the LDR’s control too heavily, so i figured that the best way to make this more usable was to add a trimmer pot in series with the LED that controls the LDR inside the VTL5C2 Vactrol. I added the trimmer after the 4k7 resistor, leaving this resistor in place. So that once the trimmer was set at minimum, the effect would be exactly like it was before this mod. This simple procedure made the controls a lot better. Maxing the controls can still be too much for most compressor users, but this solved most of the issue. In this session i also swapped a new battery snap to replace the broken one and added a modern standard power jack. After all, it did fit.


Looking at the guts, this is definitely a beauty. Real heart warming old school manufacturing. The design itself is something that may have been influenced by older Ibanez optical compressors of the seventies. Meaning that the main amplifier takes care of the compression with gain modulation controlled by the output signal. The trigger for the Vactrol is taken care by two transistors and half of a opamp. I’m not convinced that the design is completely copied from  elsewhere. Knobs on mine do not look like the original ones, but they do look reasonably good here.

Working units of this age always make me feel good. Like everything wasn’t already lost.

How does it sound?
Big and fat. Capable of boosting even the hottest pickups with clean, almost hi-fi definition. While the mod described above makes the attack time range (or depth) of the effect way more usable, the word here would still be – a classic. I think it may have been due to wide availability of OTA chips that killed the optical designs, but nowadays there are several manufacturers doing Vactrol controlled devices again.The OTAs may have been cheaper, but they never did quite catch the behavior of a light controlled circuits. So in all. Amazing box by its design, manufacturing and most important of all – the sound.

There is 2014 released reissue out. I may need to get one someday and compare.

Monarch MCO-22 Compressor

Tuesday, December 30th, 2014


What is it?
Monarch MCO-22 Compressor. Made in japan around mid to late 80’s.

Got this one in a trade. Could have bought it straight off, since the price was right. There is always something interesting in these 80’s japanese cheapos. Mainly because most of them are really good sounding and usable circuits, despite their cheap and lousy plastic overall feel. A little research pointed out that Monarch was a brand that was basically just OEM’d catalogue of Aria effect pedals. And as such, this pedal is exactly the same unit as Aria ACP-1 Compressor. This particular unit has seen some use too. The knobs are not original, but for a unit that’s seen use this isn’t a surprise. Well. At least the plastic battery compartment cover is in its place. Of course i then needed to know what the electronic design held in store, so i opened it up. Typical japanese board design with pleasing looks and a mark of hand crafted trace design.


By testing and looking at everything else, i was pretty sure the design is the standard OTA-based compressor like so many others in the genre and from the era. The stacked control board only houses the pots and and the indicator LED. No other parts of the circuit extent to the control board. The image below shows the component side and its layout. The switch (which someone has repaired with a piece of non-slip tape) and the electronic switching components are at the bottom. The diodes are for actual switching transistors that are grouped between the switching and jacks. So the effect circuit itself is placed above the jacks.


And the circuit is nothing else but a 3080 OTA-based compressor/sustainer. A quick search on the susbject showed up a DIYStompboxes forum thread where good folks were sorting out issues with a Rocktron Big Crush pedal. As Analogguru states on that thread – “Funny to see the schematic of the Aria ACP-1 (and similar units) in a Rocktron pedal.” So let’s take a peek at the Big Crush schematic that user jwbink1500 has uploaded. There are some similarities with the standard Dyna/Ross compressor, but the trigger part differs to a degree. According to Analogguru, the main difference between a Rocktron and Aria/Monarch compressor is the value of one resistor. Which he believes is an error that came to be in the cloning process. Nice design. And what’s more important…

How does it sound?
This actually sounds better than many modernized versions of the OTA compressor. The controls have good usable range and and the mushiness isn’t an issue. For the attack control, the feel is a lot better than for many similar designs. Despite its overall plastic feel, the sounds are very good. This was an interesting find and i’m actually very happy with the unit. Even if it doesn’t have the original push-on knobs in place.

Yamaha CO-10MII Compressor

Saturday, November 15th, 2014


What is it?
Yamaha CO-10MII. Made in japan, 1984. Date is determined from capacitor date codes.

Continuing with another fine specimen from Yamaha’s 10MII series. This unit is one of those i’ve sourced from a local guitar building wizard, Mr. Lindén. I know i’m a sucker for this enclosure type, so every time one shows up for sale for a reasonable price, you know i’ll be there lurking. The coin-op box. It’s just neat and has a high degree of personality. Candies keep on coming ones the bottom is opened up.


That is just beautiful. Hand drawn board design  that looks like it was created with a machine. Less acid trip style, but still visually pleasing. Very pleasing. The board thickness is also appealing. Like many japanese boxes from the era, there are two boards that make up the circuit. Many designs use the second board for controls only, but Yamaha engineers have taken everything they can  out of the space available. As the photo below shows, tis design is OTA-based and powered by Japan Radio Corporation manufactured 13600 dual OTA.


The pots are used for pretty standard set of controls. We have our output level (or volume), Attack time control and the amount of sustain. There are practically no schematics available for nearly any of the Yamaha pedals. Due to this injustice, i’m only guessing the design is your average OTA compressor in the vein of Ibanez CP9 and many others. Maybe i’ll need to do some reversing on these someday.


I’m pretty sure the CD4016 is there to take care of the electronic switching. Rest of the circuit most likely is for buffers, trigger, compression/sustainer stage and mixing amplifiers. The TA75559 is most likely taking care of the buffering or mixing. Or possibly even both.


So there you have it. A beauty. From the outside and from the inside. But even if everything made is like it should be, the pedal still may not reach to the level it may have deserved to reach. And there’s a reason for that.

How does it sound?
While everything else about this pedal is more than right, the base to it is quite dull and boring.  The tone reminds me of Ibanez CP9 a lot. In good and in bad. First of all, the control ranges are moderate at best, but it still feels like there’s something missing. That’s the kick. The same thing is also missing from the Ibanez mentioned above. While the sound is not bad, it’s not great either. For a collector, this unit has a value of its own. For a player? Nope. In my educated opinion, the mid-00’s Marshall ED1 Compressor simply does a better job and sounds better than this. This opinion doesn’t say anything the Yamaha compressor, but it says the Marshall has a high potential and user value. Even though this Yamaha compressor may not be as usable as many others. This works ands sounds the best as always on -style pedal and with single coils. If i was to give stars for these units, the CO-10MII would only get four out of then. It’s not that it’s a that bad sounding pedal. It’s about sluggish control ranges and lack of personality in its tone. Bunch of personality around this design, if we don’t take the the sound into account. Nice thing to have, but i don’t think i’ll be using this much for anything anytime soon.

Yes. If it didn’t look as great as it does, i’d be slamming it on this post. Hard.

Ibanez BP5 Bass Compressor

Tuesday, July 29th, 2014


What is it?
Ibanez BP5 Bass Comp compressor from the Soundtank series. Made in taiwan around mid 90’s.

Who would have thought that BP5 was the hardest unit to find in all the plastic Soundtanks? Well it was. The complete series did come by more easily than i expected, but there were still a couple of the units that were a lot harder to find than others. My guess is that the number of manufactured units were correlating hard with the sales. Which also means that there are tons and tons of Thrashmetals, Power Leads, 60’s Fuzzes and Tubescreamers just waiting for you to grab them. While the less succesful units are getting scarce, one should still be able to source the Bass Comp or Autowah for relatively low prices. If one keeps him/her eyes open. I did finally get one. Don’t exactly remember what i paid for this, but it wasn’t too cheap.


Once the bottom plate is out, the board looks exactly like the CP5, the guitar compressor from the same series. Once we take the board out to see it better, it is exactly the same board. Including the silk screened CP5 label. And if we look at these two closer, we see that there isn’t too much of a difference on the pedals. To be exact, the only change between CP5 and BP5 is one capacitor value. Sure. I knew about the differences before acquiring the unit, which may have been the reason i didn’t go for the ones that were out there with ridiculous price tags.


So this is pretty much the same pedal as the CP5, CP10 and CPL. Well designed and well working BA6110 VCA-based compressor.

I must wave a flag here. This is the last post about the plastic soundtanks for this blog. Yup. I’ve finally covered all of them. At the time of writing, there are still two metal cased units i’m on a hunt for. And those two are the original Thrashmetal (i’ve got three plastic ones) and the original Power Lead (i’ve got two plastic ones).

How does it sound?
If there is a difference between this unit and the CP5, i’m having real hard time hearing it. Not too noisy or mushy. I feel that the attack knob is rather useless, but that doesn’t make the rest of the features or sounds any less desirable. To sum it up, this is a poor man’s CP10. Defined and very usable unit. Superb thing with single coils. Haven’t played a lot with this on bass though.

Ibanez TC999 Tube King Compressor

Tuesday, May 20th, 2014


What is it?
Ibanez TC999 Tube King Compressor made in Japan in the 90’s.

It’s been quite long since i got this unit and took the photos (so sorry about the quality). Got this as semi-functioning unit in a trade. Problem was with the enormous amounts of hiss and interfecence when pedal was engaded. Dirk has posted a schematic up on his site, and i follewed that to see if power supply filtering had gone bad. Nope. Since the hiss was still there after i swapped the filter caps for new ones with same value, but higher voltage rating. Surely, the design isn’t meant to be used with a battery, but it did occur to me to try out the simplest possible diagnostic for power supply issues. Run it with a battery and see if the noise goes away. Yup. It does. Problem solved. Do not use a crappy power supply with this one. Some noisy squish is still present on high sustain settings, but i suspect that to be a feature. Other issues with pedal were your standard non-pedal enthusiast home made fixes. Like fastening the jack with superglue after someone had taken the threads off from the jack. Never. I mean Never fix anything with superglue nor hot glue. Please. Two of the knobs are not original, but that doesn’t slow us down too much.


Mini analysis of the design shows that the tube is there to offer the BA6110 VCA SIP chip the pre-compressed tube sound input that a good compressor wants. Dynamics of the voltage controlled amplifier is better (at least in theory) than with the standard silicon amplifier. No, the tube isn’t creating the compression. The tube is there to provide enhanced dynamics for the otherwise near standard modern Maxon/Ibanez compressors with VCAs. For the controls, the Sensitivity is basically a gain control before the tube grid. This sets the amount of signal passed to the tube. Attack and Sustain are controls for the VCA parameters, more or less the same as we’ll find in Soundtank compressors. Master is your overall volume control. The stomp switch for Boost sets the input gain of the tube for two different settings. Pretty straight forward.


Two stacked boards look like most Maxon designs from the 80s and 90s. Neat, but somewhat dull. Overall, it is a compressor that has some good thinking and engineering involved in its design.

How does it sound?
Loud and mellow compression, with some noisy squish when sustain is maxed. The boost isn’t as clean as i hoped, but it’ll be enough for many purposes. Design part left me a bit puzzled or hoping to get more out of it. Guess it’s safe to assume that new ideas do not necessarily go hand in hand with “better”. It’s not bad sounding compression, but you’ll be better of with Ibanez CP5/CP10/CPL, Digitech Main squeeze or Marshall Ed. But yes. It has a tube in it. You’ll need to weight if its Mojo or brutal usability you’re after. You’ll get a better sounding booster out of almost any cheap boost pedal.

DOD FX80B Compressor Sustainer

Monday, May 12th, 2014


What is it?
DOD FX80-B Compressor Sustainer from XF-series. Made in USA in 1988.

This pedal had been on my want list for quite some time. The biggest reason for simply not buying it was that these units sell for ridiculous prices here where i live. The one man (wikipedia link in finnish), who is deservedly considered as finnish guitar god used one, so it is in everyone’s interest to ask for way too much for these units. No matter what the condition they are in. For me, the idea of paying what these usually go for wasn’t too appealing. So i was looking for one on ebay and found this unit as broken one. Since the battery door was in tact and the pictures showed an unit that was in good condition, i snatched it for about the half of the money what people usually ask for these here. On the item description it said only that the dc-jack was missing, but the unit was in perfect shape otherwise – and it was working with a battery. Once the unit arrived i checked if the DC jack was missing or what was the problem. There wasn’t any. Only thing missing was the nut ot the jack. The jack itself was inside the box, still wired and in working order. Went through my box of crud and found a nut that fit. So, with basically zero repairing work, i got myself a “Pulliaiskompura” for a very nice price.


As always, there are nice collection of information about the unit at America’s Pedal. And here’s a original factory schematic of the earlier model with middle pot labeled “Attack”. The circuit is more or less the same on earlier and later versions. Either way, it shares a lot in design with original MXR Dyna Comp, including CA3080 OTA on board.


Board design and everything else is pretty much the same with all the other FX serie pedals from the era. A battery door that can easily be misplaced (Someone should make a batch of these doors as a spare parts – there could be some real money in that. Hell, i’d buy 5 immideately.) and the DC jack takes only 3,5mm positive tip supplies. Standard DOD flip-flop bypass and so on.

Edit! I studied the two available schematics a bit further. While the circuits have similarities, i think it’s worth noting that version with “Attack” control is based on CA3094 OTA, while the later one with “Release” control is based on CA3080. This means that there are distinct differences between the circuits and the latter version is somewhat closer to other OTA-based compressors around than the former. Haven’t had a pleasure to compare the two side by side, so i can’t be sure how big of a difference these changes are. Schematic for the unit above can be viewed here.

How does it sound?
For the later, “Release” version – Soft, transparent compression that one easily forgets that it’s engaged. The difference kicks in once it’s turned off. In my personal opinion, the sound is definitely one of the best for a OTA-based compressor i’ve played with. So the reputation isn’t false. Where as most of the CA3080-based compressors feel mushy and noisy, this one keeps the excess hisses mostly away. Sure, it doesn’t sound nearly as good as optical compressors, but for OTA-based – this is the king.

Danelectro DJ9 Surf & Turf Compressor

Tuesday, October 1st, 2013


What is it?
Danelectro DJ-9 Surf & Turf compressor from Mini series.

Finally. One of these that make the original look bad. Like i”ve pointed out on numerous occasions, to refine or rediesign existing design, the result should always be better than the original. Not much poin if it isn’t. Here we have your standard CA3080 OTA-based compressor that derives from Dyna/Ross. In reality the design is so close, that there’s not that much difference to the original 70s designs. You can do the comparison yourself. Surf & Turf by Cow4prez and original Dyna by AMZFX.


Prime example of succesful redesign. Even if the build quality of my unit is slightly sub-par in build quality with the best ones in the mini series, it’s still good. Much better unit to spend your hard earned cash on than current Dunlop Dyna.

How does it sound?
Close, if not exactly the sound of old 70s Dyna comp in compact box. Meaning that it is not the shock effect like current Dunlop versions, but the usable, warm compression with slight vintage mush due to its operational transconductance amplifier. So in a few words – really good sounding usable compressor.

Ibanez CP5 Compressor

Friday, September 6th, 2013


What is it?
Ibanez CP5 Compressor from Soundtank series in plastic enclosure. Serial points to somewhere around ’95-97. Date is based on a educated guess, as always with these.

First off. Ibanez compressors tend to use somewhat obscure OTA replacement in a few designs. The 9-pin  SIP-chip in question is BA6110, which is in fact a VC opamp. The datasheet doesn’t have a word about transconductance. It does talk about voltage controlled amplifiers, filters and oscillators. While the chip is way different from the obvious CA3080(A/E) found in MXR Dyna, Ross Comp and about a hundered different derivatives, it can do the same thing. Ibanez uses the same SIP-chip in only tremolo it ever produced, the TL5 – only there the VCA is harnessed to be used with LFO instead of controlling it with the input signal’s voltage. More about the tremolo once we get to it.. This post is about the compressor.


To study the schematic, you can check it out on Dirk’s page. His trace is beautiful work of art as always. All the other stuff going on with the circuit are relatively close to Dyna/Ross, so the base design is and isn’t a ripoff at the same time. I’m not quite familiar where in the Ibanez/Maxon design timeline did the BA6110 chip arrive, but it seems that the Master series CPL was the first one. Followed by CP10 and this circuit. Which are, all three of them, pretty much the same thing. In other words, an VCA adaptation of CP9, which uses more traditional LM16900 dual OTA. Which is, CP9 i mean, actually Dyna/Ross comp with dual OTA (second half unused). So the histroy behind this Soundtank CP5 is pretty clear. This time, the design revamped by the Maxon/Ibanez  team is better than the original.

I can say this with confidence. All four mentioned above do work and sound a lot better than currect Dunlop/MXR version of the Dyna.

How does it sound?
One of the great ones. Where as MXR Dyna is a lot more like shock effect with it compressing way too much even on minimum settings – This one can be used on all the time without excess noisy mushiness. Of course it can be turned to the max, which makes it quite close to Dyna. In a few words – Really good sounding compressor with classic feel to its sound. Doesn’t give you as much noisy mush as CA3080 designs, but good compression that thrives with a telecaster.