Planning to mod my 4 channel amp

[johnthedoctor]

I've been running a stock T-Amp for a week and like the sound. except for the bass from my vintage speakers.

http://www.radiopagajiba.latbs.lv/RRR/simfonia.htm

When using my tuner it's a one note boom box. Some improvment using the PC as source as I could use the soundcards EQ (TB Santa Cruz) but still lousy bass.

I then tried feeding the T-Amp from the pre-out of my Toshiba SB-404S and wow what a difference, I can now tell the difference between an upright and an electric bass, different bass notes as well. The T-Amp vol is at 12 o'clock, the Toshibas' at 2.5 and I've got both volume and clarity. Not clarity like the singer being in the room but a vast improvement over the Toshibas' amp modules.

http://zielknijper.student.utwente.n...4s/page_01.htm

The Toshiba/Simfonia setup has never been tiring to listen to despite the 'muddiness' ( pre T-Amp it was running 24/7) so for my first project I'm going to try and get them as good as I can.

Objectives:

1) Best stereo possible, keeping the original Simfonia drivers if possible.

2) Easy switching to 5.1 for watching DVDs. (PC source.)

3) Keep all the original functions of the Toshiba, headphone outs and psuedo 4 channel mainly.

The Plan:

A) Bi-amp the Simfonias using either Amp3 or Charlize. (I need advice as to whether tri-amping is better enough to go for it.)

B) Monica2 with SP/DIF coming from HagUsb for the Simfonias. (Inside Toshiba.)

C) Use T-Amp circuit board for rear speakers.

D) Feed front speakers with usb cable to Toshiba. Rear speakers, sub and centre fed from soundcard analogue outputs. (Amps yet to be chosen for sub and centre.)

E) Separate headphone amps.

The problems:

Only basic soldering skills, last electronics experience was repairing TVs before VCRs were common. I've never designed a circuit.

Budget can run to 2 x Charlize, Monica2 and HagUsb kit but if more class D amps are needed I'll probably have to bite the bullet and attempt Amp3.

All I know about speakers I've learned from this site in the last few months and it's making my head swim. Seems a worthy enough project to increase my understanding though, I'd like to be able to measure their performance.

Comments and ideas welcome, especially potential problems I might encounter.

Thanks.

[Pano]

Interesting speakers and "Radiola". Latvian? Do you have the radio unit or just the speakers? That radio rules! Reminds me of a great old Grundig I had in the 70s, only better.

Vintage stuff like that is cool, but is usually very bass shy. I would image that with a Sonic Impact you'd have no bass at all.

As for bi-amp vs triamp, I don't think you need to triamp in a passive configuration like that. Just use one amp per side, highs and mids one channel, lows on the other. Be sure there is no common earth between the sections - you may have to rewire the crossover.

If you haven't solder in 25 years, don't take on an AMP3! Try the AMP6 instead, much easier. Nice amp, too. Or buy a Charlize if you don't want to build the amps.

Best of luck with the crazy project!!

[johnthedoctor]

There's been a few of those Latvian Rigondas on ebay (UK) recently. afaik the radio has a tube powered motor to control the tuning. I only have the speakers, was tempted by the auctions but no room here for more stuff. You're right, no low bass (can hear the lowest notes of a piano but it's quiet) but the current Toshiba/T-Amp/Rigonda setup makes a cello sing sweetly.

The project is delayed while I listen to all my CDs and vinyl again.

[johnthedoctor]

I haven't fgured how to use Speaker Workshop yet so I installed David Taylors toneburst generator and played around with it.

With the Toshibas' bass set to zero (best listening) the bass disappears completely at 50hz, just clicks.

With the bass set to midway I can just hear the tone at 30hz which is what I 'thought' it was going down to with the bass set to zero.

With the bass turned to full I can hear the 'growl' at 24hz but at 23hz it becomes like a high pitched tone. (Not good I guess.)

All with 0db attenuation.

Does this suggest the speakers are capable of giving decent bass once I've learned how to set them up right with class D amps?