Marantz 8B

[mech986]

Thank you very much for your help :thmbsp:

If i understand well, i just need to "divide" the signal in two at the input and converge it again at the output (taking care of the ohm of the speaker).

I think i'll do it outside, so no modifications made in the inside.

Thanls very much again

Perhaps a little lost in translation here.

what you need is a mono jack output splitter on one channel of your preamp to a pair of RCA's that will feed the same signal to each channel of the 8B stereo amp. Then connect the output grounds together to the negative speaker connection, and your selected output taps (likely the 16 ohm) together to the positive speaker connection.

Same with other channel.

You could construct your own from quality gold plated parts. You can use female ends which then hook into your current RCA interconnects or build your own cables.

Here's a sample but I'd try to get better quality than this.
RCA mono adapter to 2 channel

Or this:
RCA Gold adapter

Not sure if either Parts Express or Radio Shack will ship to Spain but there must be someone in Spain, Great Britain, or the EU which has a similar product and can ship to you.

 

[cholopa]

Thanks for all the info.

I think i understood well how to convert them to mono.

I have bought this:

http://www.ebay.es/itm/350302674979...X:IT&_trksid=p3984.m1439.l2649#ht_2073wt_1193

(i do the split in the amp instead of the preamp)

And this:

http://www.ebay.es/itm/160618248872?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649


Someone has told me that i should change the capacitors, because if they fail, one transformer could brake and then the repair would be almost imposible.

I don't like the idea of changing anything, but don't want to brake the amps, so i would like to know your opinion on this.

I think the best thnig to do is don't change nothing, but check from time to time if there is any leakage at the capacitors. What do you think about that?

About the fuse holder, i need someones help. At:

http://timeless-audio.com/svcdept.html

They tell me the cannot send the fuseholder to Spain. I would need someone from this forum to help me, i can buy the fuseholder, send it to you and then you send it to me. Of course i would pay the fuseholder, the shipment to your home, and the shipment to Spain, an five extra dollars for you to have a beer. :thmbsp:

regards,

 

[bobabode]

Thanks for all the info.

I think i understood well how to convert them to mono.

I have bought this:

http://www.ebay.es/itm/350302674979...X:IT&_trksid=p3984.m1439.l2649#ht_2073wt_1193

(i do the split in the amp instead of the preamp)

And this:

http://www.ebay.es/itm/160618248872?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649


Someone has told me that i should change the capacitors, because if they fail, one transformer could brake and then the repair would be almost imposible.

I don't like the idea of changing anything, but don't want to brake the amps, so i would like to know your opinion on this.

I think the best thnig to do is don't change nothing, but check from time to time if there is any leakage at the capacitors. What do you think about that?

About the fuse holder, i need someones help. At:

http://timeless-audio.com/svcdept.html

They tell me the cannot send the fuseholder to Spain. I would need someone from this forum to help me, i can buy the fuseholder, send it to you and then you send it to me. Of course i would pay the fuseholder, the shipment to your home, and the shipment to Spain, an five extra dollars for you to have a beer. :thmbsp:

regards,

PM me , I would be happy to. Anything to help .

 

[crooner]

Using a pair of 8B's as monoblocks, even though it appears straightforward to do in the manual, is actually quite complicated electrically, since you are strapping output transformers.
For optimum performance and channel to channel matching, you will need your 8B's to be quite close in serial number.

Many folks who have tried this approach, ultimately have settled for standard stereo hookup for the 8B.

I have found the 8B to have more than enough power even for low efficiency speakers such as the Vandersteen 2 series and the LS3/5A BBC monitor loudspeaker, making strapping two amplifiers for mono unnecessary.

 

[cholopa]

Thanks very much for your offer bobabode. Your help is much appreciatte. You have an MP.

I have a couple of contacts in USA, i wil try to use them to get the fuseholder first.

regards,

 

[crooner]

This fuse holder should do the trick:

fuse holder

Apparently they ship to spain.

However, any chassis mount holder for 1/4 inch glass fuses should work.

 

[cholopa]

Thanks very much for the info cronner.

Serial number of the 8B are "relative correlative" (10288-9633).

I will try anyway, as the accesories need it are not very expensive, and check the results.

The fuse holder is not exactlly the same,and a brother of a friend is actually living in USA, i think i will be able to get it from him, thaks for the info anyway.

The only "fear" i have now is if i should change the capacitors for safety, and if this would change the characteristic of the amp, and so it should be "retune" again.

I think i can change the capacitors, but i don't have the knoledege or tools to fine tune the amp, and i doubt there is anyone in Spain with the knoledge, skill and tools to do it the right way.

regards,

 

[DanO55]

Wow very nice set up. Sorry for the loss of your father. Just be glad he is in heaven, no one who ever owned that nice a system would be sent to hell. If my father had a set up like that he would of had a large casket custom made and, well you know the rest of the story. Dear old dad, sure miss mine. God bless and really am sorry for your loss. Best to the family and welcome to audiokarma.

 

[cholopa]

Thanks for your words, my father died 10 years ago, he had a nice life, and died fairly old, so no reason to be sad. I'll surely miss my dad for the rest of mi life, but...life without dead doesn't have meaning!!!

regards,

 

[sheltie dave]

I will be the currant in the oatmeal, and vigorously ask "Why would you want to do something that risks so much for so small a gain?"

You can strap many different amps to get more power, but very, very few of them sound as good as a single stereo Marantz 8B. I would wager none are as valued or prized as an 8B.

An acquaintance loves to strap tube amps, so his Dynaco ST70s, Audio Research D76s?, and Marantz 8Bs all get strapped until they break. He spends a lot of money chasing after more power, whipping his amps until they drop, and unfortunately they don't sound nearly as good strapped as they walk into their early graves.

You can go two ways to get far more power, or cleaner power, without strapping that will not change the Marantz 8Bs one iota. Biamping the speakers with an active crossover will negate the power losses associated with passive crossovers, or sourcing a stellar vintage high powered amp will also do wonders. Both will outperform strapped 8Bs in the long run, which is where I think you are aiming.

Strapping amps is generally a commercial undertaking for sound reinforcement, while Marantz 8Bs have earned the right to be prized, pampered amps in any owner's house. Whatever route you go, please take care of these babies. They are incredibly good amps, and deserve the best of care! :thmbsp:

 

[kevco]

I will be the currant in the oatmeal, and vigorously ask "Why would you want to do something that risks so much for so small a gain?"

You can strap many different amps to get more power, but very, very few of them sound as good as a single stereo Marantz 8B. I would wager none are as valued or prized as an 8B.

An acquaintance loves to strap tube amps, so his Dynaco ST70s, Audio Research D76s?, and Marantz 8Bs all get strapped until they break. He spends a lot of money chasing after more power, whipping his amps until they drop, and unfortunately they don't sound nearly as good strapped as they walk into their early graves.

You can go two ways to get far more power, or cleaner power, without strapping that will not change the Marantz 8Bs one iota. Biamping the speakers with an active crossover will negate the power losses associated with passive crossovers, or sourcing a stellar vintage high powered amp will also do wonders. Both will outperform strapped 8Bs in the long run, which is where I think you are aiming.

Strapping amps is generally a commercial undertaking for sound reinforcement, while Marantz 8Bs have earned the right to be prized, pampered amps in any owner's house. Whatever route you go, please take care of these babies. They are incredibly good amps, and deserve the best of care! :thmbsp:

Yes!!! There is no need to do this! Other options: using the pair to biamp your speakers, selling one amp to buy more efficient speakers to better make use of 35 watts, the list goes on here...If you want 70 watt mono blocks, they can be had at a fraction of the value of these 8B's and will be operating as intended, rather than strapped in this manner. Remember also that the sound achieved by paralleling your output transformers will never be as pure as sound from a single OPT. Just because this is possible does not mean it is the way to go IMHO.

 

[crooner]

I would run a single 8B in stereo and keep the second as a backup amp. As you know, the iron in these is unobtainum and having another amp in reserve is an excellent idea.