Intro, howdy, hi, and a question: Roland SIP300

[oobedoob]

Hi there,

I've been lurking around this board for a long time, and I have to say a hearty thanks to everyone for putting in so much work to maintain such a great community. I don't know if there's anything I can add, but I'm going to start some projects soon, and I'll try the best I can to contribute.

about me: I'm an R&D EE with mostly digital/computer architecture and design exp. I have lots of good contacts with component reps/distys and board fab/assy shops, many of whom will do business with "early stage startups" ie DIYs.

(Most of the discrete analog discussions are already over my head, but this is the best reason I can think of to dust off the old books and buy new ones, right?)

Anyway, my interests are:
- modernizing of old designs (SMT, more sophisticated PCB's, digital control, etc.)
- The API project, Langevin DIY, some microphone DIY
- The "Porter" console
- Maintaining the broken stuff in my studio.....

To that end, does anyone have any schematic/service info on the Roland SIP300 preamp/eq from the '80's black/orange studio/guitar line?

Thanks again!

 

[gyraf]

Hi Oobe,

Welcome to "The Lab"..!

User manuals for all Roland products:

http://www.rolandus.com/support/product_manual.asp

Jakob E.

 

[clintrubber]

The site Jakob mentioned has the SIP300 manual, as you'll have found out, but there's no service info.
I have 1 Roland service manual, and it happens to be the SIP300. :wink:
I'll dig it up and let you know more.

Just curious, you're repairing this unit or you're using it and are just curious to what's inside ? I just browsed the manual yesterday and was wondering how the unit would sound - I haven't used it in ages.
(IIRIC it's discrete, JFETs - not sure it's completely JFET though).

BTW, if anyone has the schematic of the SIP-301 (the bass-version) I'm interested.

Bye,

Peter

 

[oobedoob]

I'm repairing/bending this one.

To my ears, it sucks donkey balls, which is why I want some help in finding out if it's broken or just needs a complete circuit-otomy. Would love to see the schematics, natch.

The EQ has potential. The distortion has potential. Overloading the input has some nice potential. But right now the overall sound is anemic, whether running direct, through an amp, line, instrument, whatever. I was expecting at least a JC120 type of feel..... oh well, what do I expect for 40 bucks.

I've never seen an SIP301. Isn't there a brochure going around that has a description of the whole product line?

Thanks.

 

[clintrubber]

Hi,

Here we are, the scans for the service manual of
the Roland SIP-300 rackmount Guitar Pre-Amp,
as requested:

http://home.hetnet.nl/~chickennerdpig/FILES/Roland/Roland_SIP-300_ServiceManual.zip

Since I only have an A4-scanner the A3-pages are spanned across three scans each.

Please download it right away or one of these days since I need
to take it down again somewhere next week.
If someone with more webspace wants to host it then that's fine by me.


Interestingly this unit appears to use a dual-FET,
I didn't remember that from when I got this service-doc.

There's also the bass-version, SIP-301, which has a compressor i.s.o.
the distortion section and different EQ-points.
I don't have any additional info about that one,
so if anyone has, please tell.

Bye,

Peter

 

[oobedoob]

Got it, thanks!

project list for the weekend just got a little longer....

 

[PRR]

> scans for the service manual of the Roland SIP-300 rackmount Guitar Pre-Amp, ...I need to take it down again... If someone with more webspace wants to host it then that's fine by me.

Roland SIP-300 rackmount Guitar Pre-Amp, 2.8Meg PDF file.

Looks like a Hi-Fi amp, not a moosical instrooment.

 

[oobedoob]

"Hi-fi" isn't the first adjective that comes to mind with this piece.....

It's not like a normal broken transistor amp sound. It's just blah. I figure there's enough real-estate in there for a fuzz-face and some other stuff. Wolf in sheeps clothing etc.

 

[tommytones]

To my ears, it sucks donkey balls

You gotta love the expressive way folks sometimes describe an event... :green: :green: :green: lmao

 

[clintrubber]

Roland SIP-300 rackmount Guitar Pre-Amp, 2.8Meg PDF file.

Looks like a Hi-Fi amp, not a moosical instrooment.

Thanks PRR, my modest webspace fills up quickly so thanks for processing & hosting.

Yep, not the usual diodeclipper. I saved mine from the trashcan were we rehearse, should hook it up again one day to see how it sounds.

 

[PRR]

> what do you think of the actual circuitry? Some interesting/funny amplifier-topologies in there. I didn't look hard, but was wondering why they're using the double-diff-input-pair topologies. I wouldn't expect problems with non-railtorail-input amps here.

The complementary differential inputs prove it was designed around 1980. There was a fad for this topology. It is generally credited to Dan Mayer and his Tiger 0.01 amplifier. It had actually been invented earlier at H-P but they kept it a secret. Dan felt it reduced distortion, but this is very debatable. Certainly perfectly good amps have been built both ways: with and without complementary inputs. The other property Dan noted and I think H-P felt was worth keeping quiet about is Base bias current cancellation. It isn't perfect but on average bias current is around 1/3rd of a plain pair. That allows larger emitter current for lower voltage noise yet larger base DC return resistor for light input loading. BTW: it isn't necessarily good for rail-to-rail inputs. With the resistor tails, I doubt this one can stay live over a wide input swing. Yes, there is a current chip with a similar topology that does hold control r2r, but it is a little more sophisticated.

> It's not like a normal broken transistor amp sound. It's just blah.

It is very-very-clean. It was, at the time, a very different sound than the Fender tube and the early simple transistor guitar amps. It is still a musically useful tool: for a guitarist and guitar with subtle colorations of string and fingers that should be heard clearly without a haze of "blending distortion". As a color-box, it sucks. And the vast majority of guitar-work really relies on a little amplifier color to fatten the thin tone from a pickup.

 

[clintrubber]

Thanks PRR for the additional comments.

Dan felt it reduced distortion, but this is very debatable.

Indeed, as I understood it you don't want the 'takeoverpoint' you get at the input-side unless you need rail to rail inputs. And it would have been funny, using a distortion-reducing topology for the overdrive-insert section.

The other property Dan noted and I think H-P felt was worth keeping quiet about is Base bias current cancellation. It isn't perfect but on average bias current is around 1/3rd of a plain pair. That allows larger emitter current for lower voltage noise yet larger base DC return resistor for light input loading.

That's an interesting property.

BTW: it isn't necessarily good for rail-to-rail inputs. With the resistor tails, I doubt this one can stay live over a wide input swing. Yes, there is a current chip with a similar topology that does hold control r2r, but it is a little more sophisticated.

Oops, typical IC-designer forgetting that discrete circuits don't throw in current sources all the time :wink:

> It's not like a normal broken transistor amp sound. It's just blah.

It is very-very-clean. It was, at the time, a very different sound than the Fender tube and the early simple transistor guitar amps. It is still a musically useful tool: for a guitarist and guitar with subtle colorations of string and fingers that should be heard clearly without a haze of "blending distortion".

I remember having heard someone play the bass-version ('301) and it was unsurprisingly very direct. Good to have such a box around then, as an alternative or as a reminder or check how the tubes boxes sound.
I'll wire mine up again.

Bye,

Peter