Long story short, I'm modernizing an old radio gram and I need some advice on the speakers. See pic
The width and height on the speaker calculations are the front of the speaker box on the radio gram. I'm no engineer but I could add a port if absolutely necessary, but I'm really trying to keep things simple to avoid mistakes. Will keeping it sealed really be bad for the sound? I'm not going for pure audiophile sound quality, its just way to complicated for me. I just want a good sound with what I have.
Also do I have to calculate in the tweeter and the damping to the volume ?
If it helps this is my replacement kit: PDF's attached
ScanSpeak
18W/8545-00
D2905/9500.00
Quad 405-2 because I know sealed boxes use more ummff
View attachment 18w-8545-00.pdf
View attachment d2905-950000.pdf
The width and height on the speaker calculations are the front of the speaker box on the radio gram. I'm no engineer but I could add a port if absolutely necessary, but I'm really trying to keep things simple to avoid mistakes. Will keeping it sealed really be bad for the sound? I'm not going for pure audiophile sound quality, its just way to complicated for me. I just want a good sound with what I have.
Also do I have to calculate in the tweeter and the damping to the volume ?
If it helps this is my replacement kit: PDF's attached
ScanSpeak
18W/8545-00
D2905/9500.00
Quad 405-2 because I know sealed boxes use more ummff
View attachment 18w-8545-00.pdf
View attachment d2905-950000.pdf
Thanks for that
Yeah I screwed up on the lts and used ft3 Need to factor in driver displacement and adjust for the fact the cross overs where designed for a transmission line enclosure. But this new dimensions feels like a regular speaker size.
Ported Box
Vas = 47.6 lts
fs = 28 Hz
Qts = 0.27
D = 136 mm
Vb = 0.45 ft3 = 12.65 lts
= L x W x H
f3 = 50.16 Hz
fb = 42.22 Hz
Dv = 2 in = 5 cm
Lv = 8.97 in = 22.01 cm
Yeah I screwed up on the lts and used ft3 Need to factor in driver displacement and adjust for the fact the cross overs where designed for a transmission line enclosure.
But this new dimensions feels like a regular speaker size.Ported Box
Vas = 47.6 lts
fs = 28 Hz
Qts = 0.27
D = 136 mm
Vb = 0.45 ft3 = 12.65 lts
= L x W x H
f3 = 50.16 Hz
fb = 42.22 Hz
Dv = 2 in = 5 cm
Lv = 8.97 in = 22.01 cm
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I'm just going to go with this Pete, seems easy enough, thanks for the help
Thats the nearest I could find
sourcing map 50mm x 122mm Speaker Port Tube Subwoofer Bass Reflex Tube Bass Woofer Box 2pcs
Will have to do !
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Its a 1967 Dynatron RG40A with 18/24 Transpower Amplifier
A Garrard AT6 MkII A turntable.
I cant find a free copy of the service manual but I assume the drivers or 12 ohm ? They are big lol
I think its a stunning looking peice of furniture
I have rigged up a amp to the speakers and they sound excellent. The old amp is in poor condition and sounded terrible, if it actually decided to turn on which was hit and miss. I dont have the knowledge time or money to fix it.
Going to line the speaker cases with some nice felt, the base is over whelming , I think they use some sort of side port as the base outlet.
So it will be hybrid modern amp with the old speakers and I;ll rig up the the turntable to see if that's any good.
I bought it assuming it would be knackered at the price, but I wanted it for a piece of music furniture. I know.. heresy stripping it like that, but I had a plan and I'm sticking to it
Going to line the speaker cases with some nice felt, the base is over whelming , I think they use some sort of side port as the base outlet.
So it will be hybrid modern amp with the old speakers and I;ll rig up the the turntable to see if that's any good.
I bought it assuming it would be knackered at the price, but I wanted it for a piece of music furniture. I know.. heresy stripping it like that, but I had a plan and I'm sticking to it
The record changer of those times had a piezoelectric capsule and the needle in those devices were reversible for 33 1/3 or 78 RPM. Is it in good condition? Can you get spare parts for the needle? If you plan to listen to good sounding vinyl, a good technician could fix the amp that is probably tube, and change the cartridge for a basic but robust MM like the Shure M-44C from which needles and bodies are still easily available, adding a basic RIAA preamplifier that you can accommodate in any available space, which is what is left over.
The speakers are housed in a bass reflex system, switching to a sealed system with other speakers with dubious EBP (in the middle, it won't work well without DSP) will not work, you will lose bass.
I would fix it, leave it original and get the knob closest to the original missing.
The speakers are housed in a bass reflex system, switching to a sealed system with other speakers with dubious EBP (in the middle, it won't work well without DSP) will not work, you will lose bass.
I would fix it, leave it original and get the knob closest to the original missing.
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I'm going to stick with the original speakers now, just stuff the reflex and line it the case with some decent underlay.
Getting the amp back to new will be expensive even if I could find someone willing to do it. I can bypass the amp the speakers have plugs at the rear that you can use for external speakers so its fine.
But thanks for the help
The Garrard AT6 Mk IIA is a good quality autochanger turntable. It has a dynamically balanced tone arm with tracking force supplied by a spring. It is likely to be fitted with a high compliance ceramic cartridge and such a combination is not unkind to vinyl. If you remove the headshell and photograph the cartridge, we may be able to identify it.
There's lots of information on the interweb on servicing Garrard turntables like this. The usual problem is solidified grease which clogs up the automatic mechanism.
Mr. Open Post Fivetide:
I will turn my other cheek as a good Christian here, although you has not thanked me for my well-intentioned advice.
The best ceramic cartridge is not close to the worst moving magnet cartridge, they were very popular in those years for their high output (voltage), and low cost, which allowed their direct coupling to any input of an amplifier of those years, the which were already incorporated into the furniture, like yours.
They did not bring a ticket for MAGNETIC PHONE.
If the amplifier you plan to use as a replacement for the original has a moving magnet cartridge phono input, (very low output, like the Shure I mentioned) do not mistakenly connect that Garrard turntable - as is - to the new amplifier you are using in that PHONO input.
Yes you can do it in AUX, TAPE, etc,
It won't explode anything, but it will sound terribly distorted.
This disc changer has the option of manual use, which is why it is ideal for attaching a magnetic capsule as I propose, without worrying about the complex disc change mechanism.
Best of luck.
I will turn my other cheek as a good Christian here, although you has not thanked me for my well-intentioned advice.
The best ceramic cartridge is not close to the worst moving magnet cartridge, they were very popular in those years for their high output (voltage), and low cost, which allowed their direct coupling to any input of an amplifier of those years, the which were already incorporated into the furniture, like yours.
They did not bring a ticket for MAGNETIC PHONE.
If the amplifier you plan to use as a replacement for the original has a moving magnet cartridge phono input, (very low output, like the Shure I mentioned) do not mistakenly connect that Garrard turntable - as is - to the new amplifier you are using in that PHONO input.
Yes you can do it in AUX, TAPE, etc,
It won't explode anything, but it will sound terribly distorted.
This disc changer has the option of manual use, which is why it is ideal for attaching a magnetic capsule as I propose, without worrying about the complex disc change mechanism.
Best of luck.
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I'm impressed with the sound of the speakers for 54 years old. I was born in 65 so this could have been a life long friend lol.
As requested needle porn attached
Mr. Open Post Fivetide:
I will turn my other cheek as a good Christian here, although you has not thanked me for my well-intentioned advice.
The best ceramic cartridge is not close to the worst moving magnet cartridge, they were very popular in those years for their high output (voltage), and low cost, which allowed their direct coupling to any input of an amplifier of those years, the which were already incorporated into the furniture, like yours.
They did not bring a ticket for MAGNETIC PHONE.
If the amplifier you plan to use as a replacement for the original has a moving magnet cartridge phono input, (very low output, like the Shure I mentioned) do not mistakenly connect that Garrard turntable - as is - to the new amplifier you are using in that PHONO input.
Yes you can do it in AUX, TAPE, etc,
It won't explode anything, but it will sound terribly distorted.
This disc changer has the option of manual use, which is why it is ideal for attaching a magnetic capsule as I propose, without worrying about the complex disc change mechanism.
Best of luck.
I did attach the turntable to the amp and it did sound distorted, I will swap the needle first after advice from people.
The cartridge is a Sonotone 9TA(HC) which was one of the better ceramic cartridges.
It's what I would have expected Dynatron to have fitted.
I used a pair of these cartridges back in the 70s in my mobile disco. Their tracking ability was excellent, even in the harsh disco environment, and they sounded great.
A replacement stylus should be available - you now know what to search for.
It's what I would have expected Dynatron to have fitted.
I used a pair of these cartridges back in the 70s in my mobile disco. Their tracking ability was excellent, even in the harsh disco environment, and they sounded great.
A replacement stylus should be available - you now know what to search for.