MA1 GERMANIUM mic pre support thread

[Sui_City]

Hi @ppa how can I get in touch with you.
I am interested in the MA1

thanks.

 

[ppa]

Hi, pm me, please.
thanks

 

[jannae66]

Hello,
I built the MA1 in a 1U rack with UTM 2522 (API Style Input, see PDF) and UTM 3503(APi Output) transformers. The preamp sounds great with condenser mics but I noticed that my ribbon mics sound very dull without highs, compared to my interface preamp. I´m assuming that the input impedance is too low on the MA1.
I don´t have no load resistor (R21) in the MA1 as recommened for API Input transformer. Could I put a 150k load resistor in there, to raise the input impedance? A 150k load resistor is also in the CAPI 312 pres....
My zobel now is
R21= not used
R22=10K
C31= 220pF

Thanks very much in advance!
Best regards,
Jan

 

[thomasdf]

how’s the input xfrmr wired ? Have you tried 150 ohms ?
What’s the ribbon mic ?

 

[jannae66]

how’s the input xfrmr wired ? Have you tried 150 ohms ?

What’s the ribbon mic ?

Hello thomas,
thanks for response. The input transformer is wired parallel, so 150 ohms. I would like to leave it parallel for higher ratio/output.
The ribbon mic is a DIY one with a FAB transformer. Around 112 ohms DCR output . On my cheapo UMC404 preamp it sounds much brighter/less duller.
Best,
Jan

 

[sr1200]

Hello,
I built the MA1 in a 1U rack with UTM 2522 (API Style Input, see PDF) and UTM 3503(APi Output) transformers. The preamp sounds great with condenser mics but I noticed that my ribbon mics sound very dull without highs, compared to my interface preamp. I´m assuming that the input impedance is too low on the MA1.
I don´t have no load resistor (R21) in the MA1 as recommened for API Input transformer. Could I put a 150k load resistor in there, to raise the input impedance? A 150k load resistor is also in the CAPI 312 pres....
My zobel now is
R21= not used
R22=10K
C31= 220pF

Thanks very much in advance!
Best regards,
Jan

Usually too low an impedance (load) on a ribbon mic gets rid of LOWS not highs. The total level of the mic drops as well, but the high end usually stays put response wise. I've used the MA1 with AEA mics and Royers (R10/121) without noticing a ton of difference. The bottom end and level isnt quite up to matching the RPQ or SSL Puredrive set to 12K, but its not killing the mics performance like you're describing. I also don't have a resistor in R21 but are using EA2622 transformers. The specs of which are REALLY close to yours. The math might be a bit off on the ratios but everything else seems to be the same. 150/600 - 10k. Have you tested with a regular dynamic mic as well? You should experience the same issue as the ribbon mic if its a problem with the preamp.

https://www.capi-gear.com/catalog/images/gallery/2622/EA2622-specs.pdf

 

[jannae66]

Usually too low an impedance (load) on a ribbon mic gets rid of LOWS not highs. The total level of the mic drops as well, but the high end usually stays put response wise. I've used the MA1 with AEA mics and Royers (R10/121) without noticing a ton of difference. The bottom end and level isnt quite up to matching the RPQ or SSL Puredrive set to 12K, but its not killing the mics performance like you're describing. I also don't have a resistor in R21 but are using EA2622 transformers. The specs of which are REALLY close to yours. The math might be a bit off on the ratios but everything else seems to be the same. 150/600 - 10k. Have you tested with a regular dynamic mic as well? You should experience the same issue as the ribbon mic if its a problem with the preamp.

https://www.capi-gear.com/catalog/images/gallery/2622/EA2622-specs.pdf

Thanks for the clarification. I´ll test it asap with a dynamic mic.

 

[jannae66]

So I tested it right with my MD21 (I don´t have my other Mics here at home) a Bumblebee RM-6 ribbon and my DIY ribbon with my acoustic guitar. There was just a tiny little bit more highs on the MD21 with the UMC404 Preamp compared to the MA1 and on the ribbons the difference was a little bigger. BUT: The highs felt a little separated from the rest. I heard of it before, when someone said this, but now I really could hear it on my own when compared to a good preamp. When I high passed the signal it was obvious that the MA1 is much better. All the frequencies fit together and there was no slight phasing sound like with the UMC404 when I let the chords on my acoustic guitar rang out. On the high passed signal the highs also felt really separated from the rest. With the MA1 it was smooth and natural, just like a nice guitar should sound.
This time I exactly measured the distance from the mic to guitar, so maybe it was my bad at the first time, that it was sounding duller because of misplacement.
But what I realized today was really that I´m very happy with this preamp. Can´t wait to record some loud drums, guitars, bass and vocals with it. With only two channels I have to decide what would be the best....

 

[sr1200]

Harmonic content on the MA1 should be a bit more. The germanium has a nice shimmer to it depending on the what you're recording. Its magical on bass and brass instruments. Glad you got it sorted. They're great pres.