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-   -   Preamp Chip LM1895 (http://www.diyaudio.com/forums/solid-state/4027-preamp-chip-lm1895.html)

r_s_dhar 13th June 2002 08:02 AM

Preamp Chip LM1895
 
I have just come across a couple of LM1895s, 14 Pin DIL chips, intended for cassette deck head preamp. The data sheet says that this is a DC feed back configuration, giving "unlimited bass" etc. etc.

Have anyone one of you used this chip? Please share information.

r_s_dhar 18th June 2002 06:30 AM

LM1897 NOT 1895
 
Sorry friends, the taphe head preamp chip I mentioned is LM1897, not 1895? Any information/advice/tips?

Thanks

Vivek 18th June 2002 09:43 AM

Do you have any links to the datasheet or any circuit you could post here.
Regards,
Vivek

r_s_dhar 22nd June 2002 06:05 AM

Data on LM1897
 
Elektor featured a full length project based on this chip, also reprinted in their 302 Circuits book. Full Data can be found in the National Semiconductor site. I have a photocopy of the write-up and would be glad to send it to you. My address:

Dr. R. Shashidhar
Reader
Department of English
Mangalore University
Mangala Gangothri -- 574 199
Karnataka State
India.

I tried the circuit and found it unbelievably quiet. The manufacturers, I thought, were for once justified in their claims. However the National people had nothing extensive on high frequency erasure in DC feedback tape head preamps.

By the way, is STK4036 available where you live? I read that this LSI has a fully complementary output stage and performs quite well in active cross over constructions.

Vivek 23rd June 2002 03:43 PM

Hi Shashidhar,
I was considering the OPA 2134-based preamps. They have found favour with many DIYers.
I have not come across the STK chip you mentioned. The common ones are the 4141 and 4171 power amp ICs. If I stumble upon them, I will inform you.
My address is Vivek Phadnis, 8/9, 4th Cross, MT Layout, 13th Cross, Malleswaram, Bangalore-560003.
I have an LM 381-based preamp circuit with bass and treble controls from Electronics For You. I could send it over if you want.
Regards,
Vivek

r_s_dhar 24th June 2002 07:28 AM

Thanks Vivek. I have read about the preamp you have mentioned. But I have a different problem. Being an Indian Classical enthusiast, I am condemned to live with tapes for some foreseeable future. CDs in this genre are expensive and there are not many to choose from. Old Maestros are ruled out.

I am therefore still living in the 60-70s era when there was so much enthusiasm for good tape and tape-head preamps.

If you are a discrete-die-hard, you could consider an all transistor configuration which also appeared in Elektor. The write-up to this project suggests that several trans connected in parallel lower noise figure significantly. You could try this one out with necessary modification in NFB.

Was it you who suggested in one of the threads that TDA7294 sounds bad?

Vivek 24th June 2002 09:03 AM

Hi,
I do not have any information about the TDA chip though I do not mind trying it.
I am not a die-hard discrete fan. I am just looking at various pre-amps, both discrete and op-amp-based. I have one discrete circuit from EFY which I am considering. I shall keep you informed about any developments.
Regards,
Vivek


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