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Author Topic: m148 bill of materials?  (Read 17360 times)

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Offline Church-Audio

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Re: m148 bill of materials?
« Reply #45 on: November 12, 2006, 07:02:17 PM »
Neve is certainly a very respected name but not the only one.  Do the Portico pre's use Sowter?
Celac


I think they do, I know Sowter does oem work for Neve so I would say yes. I know Neve are not the only name in preamps, I have been a sound engineer for 20 years and in that time, nothing I have ever used comes close to the old neve 1173 eq/preamp. It is simply the most musical sounding preamp ever made IMHO.
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Offline Chuck

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Re: m148 bill of materials?
« Reply #46 on: November 12, 2006, 07:13:45 PM »
This ESP Project #13 circuit would be almost the ideal transistor section to place after the input transformers, since it's looking for a 600 ohm input which matches perfectly with the JT-16-A's.

I don't like the idea of electrolytic capacitors in the signal path, but this would solve the problem of needing a bi-polar power supply for an op-amp... I have never built a transitor based pre-amp circuit. Does anyone know if the transistors used here are the best for this application? I would set the gain lower than the current 32 db. Maybe use a fixed metal film resistor and put a quailty 5k pot in there to use as a trim control?
Reality is merely an illusion, albeit a very persistent one.

Microphones: AKG C 480 B comb-ULS/ CK 61/ CK 63, Sennheiser MKE 2 elements,  Audix M1290-o, Micro capsule active cables w/ Naiant PFA's, Naiant MSH-1O, Naiant AKG Active cables, Church CA-11 (cardioid), (1) Nady SCM-1000 (mod)
Pre-amps: Naiant littlebox, Naiant littlekit v2.0, BM2p+ Edirol UA-5, Church STC-9000
Recorders: Sound Devices MixPre-6, iRiver iHP-120 (Rockboxed & RTC mod)

Recordings on the LMA: http://www.archive.org/bookmarks/ChuckM
Recording website & blog: http://www.timebetweenthenotes.com

Offline Celac

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Re: m148 bill of materials?
« Reply #47 on: November 13, 2006, 02:56:41 AM »
This ESP Project #13 circuit would be almost the ideal transistor section to place after the input transformers, since it's looking for a 600 ohm input which matches perfectly with the JT-16-A's.

I don't like the idea of electrolytic capacitors in the signal path, but this would solve the problem of needing a bi-polar power supply for an op-amp... I have never built a transitor based pre-amp circuit. Does anyone know if the transistors used here are the best for this application? I would set the gain lower than the current 32 db. Maybe use a fixed metal film resistor and put a quailty 5k pot in there to use as a trim control?

Hey,
Data sheet for the spec'd part may be here? http://www.datasheetcatalog.com/datasheets_pdf/B/C/5/4/BC549.shtml 

I will admit my transformer spotting skills may not be up to the test, but I can't read the nomenclature on the input.  The Portico brochure I picked up at AES just says "custom" transformer and obviously it could be mfg'ed by Sowter. Attached is a Sowter "Neve" line output.  The bobbins certainly look different. Were "Marinair" and "St. Ives" Sowter OEM products?   

I certainly respect your (Church Audio's) experience, and you are not alone in liking Neve. It was not my intention to advance the cause of one brand over another, or denigrate anyone else's opinions and ideas about transformers.  I was just suggesting another alternative to Jensen that I was aware of and that I knew was used by reputable mfg's in high quality products. 
Celac.
...can't get enough of nothing!

Did your friend consider that maybe he got a basically accurate recording of a bad P.A. system and/or a terrible-sounding performance venue? When you aim good microphones at ugly sound, the resulting recording will not be beautiful.
DSatz

Offline Church-Audio

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Re: m148 bill of materials?
« Reply #48 on: November 13, 2006, 03:06:47 AM »
This ESP Project #13 circuit would be almost the ideal transistor section to place after the input transformers, since it's looking for a 600 ohm input which matches perfectly with the JT-16-A's.

I don't like the idea of electrolytic capacitors in the signal path, but this would solve the problem of needing a bi-polar power supply for an op-amp... I have never built a transitor based pre-amp circuit. Does anyone know if the transistors used here are the best for this application? I would set the gain lower than the current 32 db. Maybe use a fixed metal film resistor and put a quailty 5k pot in there to use as a trim control?

Hey,
Data sheet for the spec'd part may be here? http://www.datasheetcatalog.com/datasheets_pdf/B/C/5/4/BC549.shtml 

I will admit my transformer spotting skills may not be up to the test, but I can't read the nomenclature on the input.  The Portico brochure I picked up at AES just says "custom" transformer and obviously it could be mfg'ed by Sowter. Attached is a Sowter "Neve" line output.  The bobbins certainly look different. Were "Marinair" and "St. Ives" Sowter OEM products?   

I certainly respect your (Church Audio's) experience, and you are not alone in liking Neve. It was not my intention to advance the cause of one brand over another, or denigrate anyone else's opinions and ideas about transformers.  I was just suggesting another alternative to Jensen that I was aware of and that I knew was used by reputable mfg's in high quality products. 
Celac.

Hi Celac the reason why the bobbins look different, as I am sure you are aware. The transformer in your picture is a chasis mount, the one in the portico is pcb mount. Sowter does make transformers for Neve, I would assume this is another Sowter transformer. Jensen is good but I think I would go with what ever Neve uses. I trust good old Rupert when it comes to preamp design :) And there maybe other preamps out there but there is only one Neve :)
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Offline Celac

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Re: m148 bill of materials?
« Reply #49 on: November 13, 2006, 04:26:56 AM »

Hi Celac the reason why the bobbins look different, as I am sure you are aware. The transformer in your picture is a chasis mount, the one in the portico is pcb mount. Sowter does make transformers for Neve, I would assume this is another Sowter transformer. Jensen is good but I think I would go with what ever Neve uses. I trust good old Rupert when it comes to preamp design :) And there maybe other preamps out there but there is only one Neve :)

Hey,
Well actually I never noticed the screw lugs for attaching it to chassis until you pointed that out. :) I was just looking at the frame and the bobbins.  I was kind of thinking that stamped or molded parts (things that could be mass produced to lower cost) might be unchanged even on a custom wound piece. 

Perhaps we could start another thread dealing with either a Neve clone or a powering scheme for field use of available modules (i.e., some kind of BAE style rack, except battery powered or a DC "lunch box").  This seems to have wandered OT and I don't want to dilute peoples focus... but a DC lunch box would be really cool though considering the # of API format pre's.
Celac.
...can't get enough of nothing!

Did your friend consider that maybe he got a basically accurate recording of a bad P.A. system and/or a terrible-sounding performance venue? When you aim good microphones at ugly sound, the resulting recording will not be beautiful.
DSatz

Offline Church-Audio

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Re: m148 bill of materials?
« Reply #50 on: November 13, 2006, 10:10:49 AM »

Hi Celac the reason why the bobbins look different, as I am sure you are aware. The transformer in your picture is a chasis mount, the one in the portico is pcb mount. Sowter does make transformers for Neve, I would assume this is another Sowter transformer. Jensen is good but I think I would go with what ever Neve uses. I trust good old Rupert when it comes to preamp design :) And there maybe other preamps out there but there is only one Neve :)

Hey,
Well actually I never noticed the screw lugs for attaching it to chassis until you pointed that out. :) I was just looking at the frame and the bobbins.  I was kind of thinking that stamped or molded parts (things that could be mass produced to lower cost) might be unchanged even on a custom wound piece. 

Perhaps we could start another thread dealing with either a Neve clone or a powering scheme for field use of available modules (i.e., some kind of BAE style rack, except battery powered or a DC "lunch box").  This seems to have wandered OT and I don't want to dilute peoples focus... but a DC lunch box would be really cool though considering the # of API format pre's.
Celac.

Yes the api stuff is very nice but it requires a split supply of atleast 15+ 15- to run correctly.
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Offline Chuck

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Re: m148 bill of materials?
« Reply #51 on: November 13, 2006, 12:03:20 PM »
From David at CineMag:

The CMMI-2C is $60.85 each plus $8 shipping.
Maybe it's worth trying?
It's also a 200 ohm input /600 ohm output 1:2 quality audio transformer.
Reality is merely an illusion, albeit a very persistent one.

Microphones: AKG C 480 B comb-ULS/ CK 61/ CK 63, Sennheiser MKE 2 elements,  Audix M1290-o, Micro capsule active cables w/ Naiant PFA's, Naiant MSH-1O, Naiant AKG Active cables, Church CA-11 (cardioid), (1) Nady SCM-1000 (mod)
Pre-amps: Naiant littlebox, Naiant littlekit v2.0, BM2p+ Edirol UA-5, Church STC-9000
Recorders: Sound Devices MixPre-6, iRiver iHP-120 (Rockboxed & RTC mod)

Recordings on the LMA: http://www.archive.org/bookmarks/ChuckM
Recording website & blog: http://www.timebetweenthenotes.com

Offline Church-Audio

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Re: m148 bill of materials?
« Reply #52 on: November 13, 2006, 12:26:13 PM »
From David at CineMag:

The CMMI-2C is $60.85 each plus $8 shipping.
Maybe it's worth trying?
It's also a 200 ohm input /600 ohm output 1:2 quality audio transformer.


The specs are not very good why did they measure distortion at -10 db? at 20k to get a reading of 0.03% wonder what that would be at +8 ? hummm I have only one word to say SOWTER.  :P
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Offline Chuck

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Re: m148 bill of materials?
« Reply #53 on: November 13, 2006, 12:38:41 PM »
Chris, I don't see a viable Sowter to use... Maybe I missed something...
200 ohm input, 600 ohm output 1:2 turns ratio is what I need.
Reality is merely an illusion, albeit a very persistent one.

Microphones: AKG C 480 B comb-ULS/ CK 61/ CK 63, Sennheiser MKE 2 elements,  Audix M1290-o, Micro capsule active cables w/ Naiant PFA's, Naiant MSH-1O, Naiant AKG Active cables, Church CA-11 (cardioid), (1) Nady SCM-1000 (mod)
Pre-amps: Naiant littlebox, Naiant littlekit v2.0, BM2p+ Edirol UA-5, Church STC-9000
Recorders: Sound Devices MixPre-6, iRiver iHP-120 (Rockboxed & RTC mod)

Recordings on the LMA: http://www.archive.org/bookmarks/ChuckM
Recording website & blog: http://www.timebetweenthenotes.com

Offline Church-Audio

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Re: m148 bill of materials?
« Reply #54 on: November 13, 2006, 01:01:35 PM »
Chris, I don't see a viable Sowter to use... Maybe I missed something...
200 ohm input, 600 ohm output 1:2 turns ratio is what I need.

Check this one out Sowter model # 3257 150+150/600CT Input/Output Transformer
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Offline Chuck

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Re: m148 bill of materials?
« Reply #55 on: November 13, 2006, 01:30:48 PM »
Chris, I don't see a viable Sowter to use... Maybe I missed something...
200 ohm input, 600 ohm output 1:2 turns ratio is what I need.

Check this one out Sowter model # 3257 150+150/600CT Input/Output Transformer


OK, I will, Thanks.
Reality is merely an illusion, albeit a very persistent one.

Microphones: AKG C 480 B comb-ULS/ CK 61/ CK 63, Sennheiser MKE 2 elements,  Audix M1290-o, Micro capsule active cables w/ Naiant PFA's, Naiant MSH-1O, Naiant AKG Active cables, Church CA-11 (cardioid), (1) Nady SCM-1000 (mod)
Pre-amps: Naiant littlebox, Naiant littlekit v2.0, BM2p+ Edirol UA-5, Church STC-9000
Recorders: Sound Devices MixPre-6, iRiver iHP-120 (Rockboxed & RTC mod)

Recordings on the LMA: http://www.archive.org/bookmarks/ChuckM
Recording website & blog: http://www.timebetweenthenotes.com

Offline it-goes-to-eleven

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Re: m148 bill of materials?
« Reply #56 on: November 18, 2006, 10:08:55 AM »
So.. the m148 is 20dB of gain.  Any idea how much is from the transformers vs. the discrete transistors?

I was doing some preamp testing the other day and was struck by how quiet the aerco is at 0db gain vs. 10dB.  At 0, you're not running through the op-amp, etc.  Though I don't have a schematic so I don't know for certain what the path is for 0dB.  It raises the possibility of running the aerco at 0 for the "transformer sound" and then using another pre for the actual gain.. The opamp in the aerco is very good and very quiet, just yet another combo option..

The aerco comes in two basic flavors.. 0-50dB of gain with a 1:1 transformer.  And a 20-70 version that gets the first 20dB from the transformer.  I wonder how the two versions compare when each is run at 20dB?

I am really itchin' to start building and tweaking a pre.

Offline Church-Audio

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Re: m148 bill of materials?
« Reply #57 on: January 03, 2007, 03:50:18 PM »
Anyone making any progress on projects?  Closest I've come lately is moving the Mouser catalog into the bathroom as a reminder to put together an order...

Anyone have any thoughts on whether transformers make a preamp more sensitive to bass vibration than non-t designs?


Thats too funny I have the digikey and mouser catalog in my bathroom too my wife loves it :)
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Offline Digital Quality

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Re: m148 bill of materials?
« Reply #58 on: January 03, 2007, 04:01:07 PM »
I got a pair of Jensen transformers and some LM4562 op amps gathered up but that's about it so far. The transformers just showed up the other day. I picked out the JT-16A for my project. The 11K-APC matched my noise figure better but the spec said that it was for ultra low noise current app and my opamp isn't that low on the noise current side. Plus, I wanted to get the version with the bracket for nicer mounting.

So now I'm deciding how to power it. I wouldn't mind using the same cells as Doug used but it would be nice to come up with some sort of switchable power bus so the cells could be charged in parallel instead of in series. A 6V or 12V charger would be so much nicer to deal with than 52 or so....


I think Chuck might have his amp done already - is that right man?

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Offline Chuck

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Re: m148 bill of materials?
« Reply #59 on: January 03, 2007, 04:34:55 PM »
Yup, parts catalogs in the bathroom here too :)

I have the hammond case and I started drilling holes in it last weekend. My project has changed, many times. I really need a field mixer at this time more than I need a transformer based microphone pre-amp. So, I'm making a four in, two out mixer. The first input will be XLR or RCA awitchable, so that when I'm ready to add the transformers for the mic pre, it'll be set. I plan to use a very simple summing mixer to mixe the line inputs, so It will look very close to the Jensen pre-amp design we have been talking about. To muddle things further, i just bought a Rolls MX28 that I plan to modify, so Eventually that will be my line mixer and the project in the hammond enclosure will be a mic pre-amp. I'm assembling the parts , like good film capacitors, metal film resistors, panel mount jacks etc when I see them cheap on eBay or anywhere else. I have most of the parts, except the transformers for the mic pre-amp part.

One more thing to add... Jon, over at Naiant Studio has a summing mixer that he is working on it looks like it can run on 12v DC. He's looking for some more folks to maybe go in on a group buy of the circuit boards. I'm probably going to use the circuit he designed as the summing part of my project, with the Jensen transformers (eventually as the impedence matching and a bit of gain) for the mic pre-amp section. Give him a shout. I've found him to be very easy to work with.

Chuck
Reality is merely an illusion, albeit a very persistent one.

Microphones: AKG C 480 B comb-ULS/ CK 61/ CK 63, Sennheiser MKE 2 elements,  Audix M1290-o, Micro capsule active cables w/ Naiant PFA's, Naiant MSH-1O, Naiant AKG Active cables, Church CA-11 (cardioid), (1) Nady SCM-1000 (mod)
Pre-amps: Naiant littlebox, Naiant littlekit v2.0, BM2p+ Edirol UA-5, Church STC-9000
Recorders: Sound Devices MixPre-6, iRiver iHP-120 (Rockboxed & RTC mod)

Recordings on the LMA: http://www.archive.org/bookmarks/ChuckM
Recording website & blog: http://www.timebetweenthenotes.com

 

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