ruffrecords
Well-known member
They used it for mastering vinyl so perhaps it might also be good for mastering in general?leadbreath said:
Cheers
Ian
RS127 RS135
- Thread starter ruffrecords
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Cheers
Ian
skal1
Well-known member
yeah 
stepped controls all the way
regards
Skal
stepped controls all the wayregards
Skal
Well I would prefer to have the original Brilliance modules,
this is me at Abbey Road with the original units. What I would do to have some hours again with those units and be able to measure and trace them.
this is me at Abbey Road with the original units. What I would do to have some hours again with those units and be able to measure and trace them.
leadbreath
Well-known member
Any news on this.....?
Dylan W posted a schematic of the TG12412 EQ in the docs: https://groupdiy.com/index.php?topic=51980.msg820969
The frequencies of this EQ are the same as the frequencies on the RS56, but it's a 4-band EQ instead of the 3-band passive design of the RS56.
Anyway, there's a 8k band on the TG12412, so maybe you could use this?
The frequencies of this EQ are the same as the frequencies on the RS56, but it's a 4-band EQ instead of the 3-band passive design of the RS56.
Anyway, there's a 8k band on the TG12412, so maybe you could use this?
ruffrecords
Well-known member
wlinart said:
The TG12412 is an active EQ whereas the the RS127 etc were all passive. This means that, although the frequencies may be the same, unfortunately the component values will be quite different.
Cheers
Ian
ruffrecords
Well-known member
wlinart said:oh, bummer, i thought it would at least help
The circuit configuration and the inductor values determine the the shape of the response and in particular the sharpness of mid boost/cut. I know that many classic passive EQs had quite modest values of sharpness. I could work out the sharpness of the TG EQ but I don't think it will tell me a lot. Either it is similar to the old passive EQs or, like more modern EQs, it will be a lot sharper. Either way it does not tell me much.
Bottom line is there are only so many ways of building a passive EQ with given frequency bands and sharpness so if you know the shape of the EQ you can design one to do the same. This is basically what I did with the REDD EQ (which is the REDD desk bass and treble plus my version of the RS127) plus I realised the Helios EQ designer used to work at Abbey road so I guessed he based the Helios on the REDD EQ and the RS127. So in that sense I have already done the RS127. The RS135 only adds one extra frequency. SO I could create a 100% passive version of the REDD EQ with the added 8KHz of the RS135 and arrange it so it presented a 600 ohm load and could feed into a 10K line input to make up the insertion loss. As much as anything I wanted to look at the original schematics to see how close my design was to the original.
Cheers
Ian
Very interesting, I didn't realise this.
Let's hope that eventually some measurements pop up, and that you could do your magic
Let me use this opportunity to thank you for your amazing posts about everything EMI-related, I'm quite interested in that gear, so your posts are very helpful.
Here is a link i found about some EMI eq's. http://www.atomheartstudio.com/emi/EMIEQ.html The EMI 920 EQ on that page could maybe help?
Let's hope that eventually some measurements pop up, and that you could do your magic
Let me use this opportunity to thank you for your amazing posts about everything EMI-related, I'm quite interested in that gear, so your posts are very helpful.
Here is a link i found about some EMI eq's. http://www.atomheartstudio.com/emi/EMIEQ.html The EMI 920 EQ on that page could maybe help?
leadbreath
Well-known member
hopefully Whoops can get some photos of capacitor/inductor values, that will help a lot...
ruffrecords
Well-known member
The EMI 920 looks very interesting - it has many features in common with the 127 and 134. I have emailed the guy who owns it for further info.
Cheers
Ian
Cheers
Ian
I love this place!!
You guys rock!
You guys rock!
Lee_M
Well-known member
That EMI 920 seems to allow cut and boost on the treble and bass bands, The controls don't look complicated enough for that to be done passively.
The presence band is most likely passive, Considering it only allows boost.
The BBC AM22/15 EQ (at the top of that page) has the same functionality (low & high shelves, passive presence band) and similar frequency points to the 920.
I can't find the AM22/15 schematic, But the AM22/2 seems fairly close.
http://www.bbceng.info/ti/eqpt/AM22_2.pdf
The presence band is most likely passive, Considering it only allows boost.
The BBC AM22/15 EQ (at the top of that page) has the same functionality (low & high shelves, passive presence band) and similar frequency points to the 920.
I can't find the AM22/15 schematic, But the AM22/2 seems fairly close.
http://www.bbceng.info/ti/eqpt/AM22_2.pdf
ruffrecords
Well-known member
Lee_M said:
Looks can be deceiving. In the he schematic you posted, the bass, treble and presence are all active.
Cheers
Ian
leadbreath said:
I sent the photos I could to Ian already some time ago.
Components are big and really close to each other, the back of the unit is quite busy.
leadbreath how hard do you want one more project on your bench?
LOOLOL
How many unfinished projects do you have already?
If you're like me you have more unfinished projects around you than the free time you'll have in the next 10 years !!!!
Tekay
Well-known member
ruffrecords said:
Would love to see a schematics for the old 839/1 germanium plug-in amps used in the 920 EQ 8)
ruffrecords
Well-known member
I am rapidly coming to the conclusion that there is very little difference between a 600 ohm version my REDD EQ, the RS127/135 and the 10dB mastering EQ I am developing. The REDD EQ just complicates the mid cut/boost by maintianing the same Q for cut as for boost.
So I think I should create a common design for a 600 ohms EQ based on the master EQ and using inductor/capacitor values scaled from my current REDD EQ to account for the impedance change. This could then be built as a 600 ohm REDD EQ or as the mastering EQ just by using different switches and LC components..
Cheers
ian
So I think I should create a common design for a 600 ohms EQ based on the master EQ and using inductor/capacitor values scaled from my current REDD EQ to account for the impedance change. This could then be built as a 600 ohm REDD EQ or as the mastering EQ just by using different switches and LC components..
Cheers
ian
leadbreath
Well-known member
I sent the photos I could to Ian already some time ago.
Components are big and really close to each other, the back of the unit is quite busy.
leadbreath how hard do you want one more project on your bench?
LOOLOL
How many unfinished projects do you have already?
If you're like me you have more unfinished projects around you than the free time you'll have in the next 10 years !!!!
;D
Too true!!
Lee_M
Well-known member
ruffrecords said:
Oops, I actually meant the AM1/4...That's what I get for trusting my memory!
http://www.bbceng.info/ti/eqpt/AM1_4.pdf
ruffrecords
Well-known member
Lee_M said:
That one is half and half. The bass and treble are active but the mid boost is passive.
Cheers
Ian
