marmac valve head

cxdavid · 23rd June 2011, 11:35 PM

hi got this the other day its sounds great even though its never had new valves.
gonna put new ones in soon as, its very hissy on the treble, any idea how i might cure this....or has any one else got aany marmac amps of any other info on them. was built in early 70 s in sligo ireland..thanx again cheers

nigelwright7557 · 24th June 2011, 12:28 AM

Looks like a hybrid valve SS amp.

It could be the old style op amps causing the excessive hiss.
Might be worth replacing them with newer op amps.

I used to have a Simms-Watts amp that looked very similar (case wise) and that could really rock when turned up. Despite being 100watts I couldnt stand next to it becasue it was so loud.

cxdavid · 24th June 2011, 07:58 AM

hi thanxs for interest, you are the second person to suggest changing the op amps, so think it could be the thing to do. it currently uses LM741cn which are old. was told to check out LM833, if it uses dual op amps. however i think its not using dual, could ya recomend a replacement......thanxs.
this too is loud and great sound too.

24th June 2011, 12:28 AM	#2
nigelwright7557 diyAudio Member Join Date: Apr 2008 Location: Carlisle, England	Looks like a hybrid valve SS amp. It could be the old style op amps causing the excessive hiss. Might be worth replacing them with newer op amps. I used to have a Simms-Watts amp that looked very similar (case wise) and that could really rock when turned up. Despite being 100watts I couldnt stand next to it becasue it was so loud. __________________ http://www.murtonpikesystems.co.uk PCBCAD40 pcb design software.

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24th June 2011, 07:58 AM	#3
cxdavid diyAudio Member Join Date: Jun 2011	hi thanxs for interest, you are the second person to suggest changing the op amps, so think it could be the thing to do. it currently uses LM741cn which are old. was told to check out LM833, if it uses dual op amps. however i think its not using dual, could ya recomend a replacement......thanxs. this too is loud and great sound too.

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