Doc modding Marantz imperial 7

[karatestu]

Yes the journey is very exciting, rewarding and has taught me a thing or two along the way. Still more to be learned.

The isobarics are going to happen soon

I am honoured that people find my experiments and thoughts worthy of taking any notice of. It is not like I am some speaker building guru - these are my first DIY speakers ever. It has helped train my ear a hell of a lot and led me to listen to the music not the hifi. Above all it has hammered home the importance of believing in yourself, trusting your own ears (not some one else's) and ignoring those who say it can not work (for what ever reason).

Scrutiny by more experienced enthusiasts than me will be interesting. Hope I can take the criticism (if any). Ultimately I will have to please the wife to some degree as she will have to look at them as much as me although to be honest I am not bothered what they look like. She is rather accommodating in general so it should not be too hard a sell, especially as she loves music as much as me

Looking forward to your speaker building thread Simon when you get around to it. At this rate I will still be on my journey when you start. Don't bother with an upfiring tweeter. I think it messes things up a touch. Was nice to hear while it lasted as it did bring some things to the party. I will share my knowledge with anyone who needs it. And the Doc is here of course and Stevetheshadow.

[antonio66]

Still plenty for us to look forward too. Hope the house move goes smoothly.

[karatestu]

A bit of progress today. Opened up one of the bass cubes, cut some wood strips and they fit nicely. The back baffle will be offered up to these, screwed in and sealed for air tightness.



I have also managed to do one of the bass driver cut out's. Not secured in yet but that will have to be for another day.



There is precision engineering here and still using up bits of old ikea furniture The front driver wiring will go through small holes at either side of the back driver and then sealed. I had a thought that if using NVA speaker cable one could put the positive and negative binding posts on opposite sides of the back panel and so keep the wires away from each other all the way

Getting excited already ...................

[karatestu]

Some more work done on these (relief from the room treatment saga). I now have two rear baffles measured and cut with drivers attached ready to go in the big bass cubes. Both cubes are open and the wooden strips are yet to be screwed in fully. Then the baffle can go up to them and be screwed and sealed.



Edging closer to having these ready for listening Even more excited now Should be finished next week

[karatestu]

No pictures today, I couldn't be arsed.

Wires have been soldered to the new bass drivers - used 2mm sq solid core from some twin & earth that was lying around on the farm. Not too old so wont be oxidised. Drilled a hole either side of the rear bass driver for the front driver's wires to pass through. Also drilled another couple of holes through the back panel for the two extra wires from the back bass driver.

All I need to do now is finish attaching the wooden lats around the inside of the cab attach the new rear baffles and put the rear panels back on.

I take it the best approach is to wire the bass drivers in parallel ? That will be a 4 ohm load for the bass amp. Apart from creating a 16 ohm load for the amp, what will happen if I wire them in series ?

[Dr Bunsen Honeydew]

Try it and see, you know you will anyway.

People don't understand loads (like most things) all it does is make the amp lean to driving current in low impedances and more to voltage in higher impedances. Which do your amps prefer. Your kit amps are up to it being designed as current amps mostly. AP20 being small may be a bit pushed for current in parallel config but fine in series. Anyway I thought you were going to amp them individually.

[antonio66]

"relief from the room treatment saga)." When you've finished your Doc mod speakers I will look forward to your home made room treatments and the results thereof.

[Dr Bunsen Honeydew]

He already designed and built a bass one

[karatestu]

You are right Doc, i will be trying both ways - parallel and series. I don't understand a lot of things but know enough to be dangerous.

Not sure what my amps like. They are Avondale NCC200 with 350VA per monobloc run at 50-0-50 Volts. I will have to ask Les.

If i amp each driver individually i will need 8 mono amplifiers I will start with one mono per bass cube and one mono per small cube. 4 mono amps in total.

Home made room treatments- wonder what i can find on the farm to make them. Bales of straw

[IPNIGHTLY]

You fancy off loading those marantz cabs now you are not using them ? I could do with a project.