Amp Deal of the Century!

billbillw

madmax wrote: »

At the original price I would not have bought one but for $15 its a no brainer. They sound good.

From the website, for two amps, it works out to about $20.50 a piece w/shipping/tax...still a real steal! The current T-amp goes for $50+shipping from P.E. Two of these for less than one T-amp.

maximillian

Does it clip running them at reasonable levels? If that is the case, then I don't want to drive any of my "good" speakers and run the risk of blowing a tweeter.

madmax

It could but you would be able to hear it. Worst case amp for speaker damage is at about 100 watts per channel. This amp is maybe 30 or 50 wpc.

ben62670

maximillian wrote: »

Does it clip running them at reasonable levels? If that is the case, then I don't want to drive any of my "good" speakers and run the risk of blowing a tweeter.

No problems driving speakers at pretty high levels. A couple minor mods are in order to get surprisingly good results out of these little gems. Bypass the whole front board which ditches the lame tone controls, cheap pots, and SQ killing caps they have all over the thing. Really simple, and someone would be glad to help you through if you needed help.

Ben

billbillw

ben62670 wrote: »

No problems driving speakers at pretty high levels. A couple minor mods are in order to get surprisingly good results out of these little gems. Bypass the whole front board which ditches the lame tone controls, cheap pots, and SQ killing caps they have all over the thing. Really simple, and someone would be glad to help you through if you needed help.

Ben

Assuming I would want to use this for a computer rig, what would you be using for volume control if you removed the entire tone control board? Is the range of the volume control in Windows enough to control this adequately or do you need to install a separate volume pot?

ben62670

billbillw wrote: »

Assuming I would want to use this for a computer rig, what would you be using for volume control if you removed the entire tone control board? Is the range of the volume control in Windows enough to control this adequately or do you need to install a separate volume pot?

Correct. Your sound card would be the pre. You could easily wire in a pot to control volume, but straight from the sound card works best, and a decent volume control would cost as much as the amp. I will be back in FL Tuesday, and caught up on Wednesday. If you want I will be available to Polkies to help out with the mod. I am using mine to power some custom monitors with Polk woofers, and morel tweeters. Work very good. It goes louder then you would ever want to listen to for any length of time. I even drove my RTA15rdo's with it. Bass slam wasn't there with the 4 woofers, but it did better than I expected.

MillerLiteScott

This little amp sounded pretty good with the Pair of RTA 8 TL's I picked up. I actually liked the mid bass clarity this combo offered. No real deep bass but more than you would expect for such a modest outlay of $.

Scott

ben62670

Oops

MillerLiteScott

No amps coming my way that I know of.

ben62670

MillerLiteScott wrote: »

No amps coming my way that I know of.

Sorry. Wrong Scott:o

ELSock

if i picked up a couple of these would someone mod them for me? as easy as it probably is, i'm about as delicate as a rhino... so the help would be greatly appreciated.

ben62670

Where do you live? I have modded 3 of these, and helped a few others. If you want to send them to me I can do the mods for you.
Ben

MillerLiteScott

The mods are very easy.

ben62670

If I remember when I get home I'll post some pics on where to attach the input wires to the main board. You can bypass a couple extra components on the main board to get the bass to go a little deeper, and clean it up very nicely in the mids, and highs.

ELSock

i appreciate the help, and i will most likely look into this very very soon.
and for the record, i live in Ma.

billbillw

My two came tonight. Definitely worth ~$20 each (w/shipping-tax).
The receiver board removal took all of 2 minutes each. Couldn't be easier really.
Not overly impressed with the sound, but they can push a pair of Mon 7B pretty loud and for their intended purpose (pushing deck speakers and/or my computer rig), they will more than suffice and for the cost, it is an absolute steal.

Oddly, the balance adjustment is backwards on both amps. They are a little noisy too. Hearing slight buzz through one or both channels on each amp. With the one I'm listening to now, the buzz seems to be diminishing the longer I have it on though.

MillerLiteScott

Mine does not have any buzz and I just put the speaker wire into the opposite speaker output to correct the Left/Right issue. Besides it was only $15.

Scott

ben62670

1.) Remove the daughter board.
2.) On the front board with the knobs remove the wires that lead to the inputs.
3.) Remove the wires that run from the front board to the main board.
4.) cut the wires from the RCA jacks near the front panel connector.
5.) Locate the input wires on the main board. They should be L G R. They are on the right side of the group of wires.
6.) Tie the input wires from the RCA's directly to the input wires on the main board.

This mod bypasses all the knobs, op-amps, resistors, and low quality caps that kill the SQ on these little amps. You will have no volume control with this mod. Your source will need variable outs. Such as an Ipod, computer, or a CD player with variable outs.

ben62670

billbillw wrote: »

My two came tonight. Definitely worth ~$20 each (w/shipping-tax).
The receiver board removal took all of 2 minutes each. Couldn't be easier really.
Not overly impressed with the sound, but they can push a pair of Mon 7B pretty loud and for their intended purpose (pushing deck speakers and/or my computer rig), they will more than suffice and for the cost, it is an absolute steal.

Oddly, the balance adjustment is backwards on both amps. They are a little noisy too. Hearing slight buzz through one or both channels on each amp. With the one I'm listening to now, the buzz seems to be diminishing the longer I have it on though.

You can loosen, and rotate the toridal transformer till the buzz goes away;)

billbillw

ben62670 wrote: »

You can loosen, and rotate the toridal transformer till the buzz goes away;)

Actually, most, if not all the buzz is gone in the one that I am listening to this evening. I'll probably use that one as is for a few weeks, then dig into it further to do some mods. For the one that I'm going to use on my deck, I will leave it stock because I'll need the volume control out there. Its hard to be critical of sound in that type of environment anyway.

pmlewis

I just got mine yesterday. The mod was very quick and easy. The hardest part was getting the feet off the case. I have not had time to put it to use yet but I have one question. How come we can use the outputs as inputs without switching around any cables for the RCA outs? I am not very well versed on amp design/theory and was just wondering why it worked.

billbillw

pmlewis wrote: »

I just got mine yesterday. The mod was very quick and easy. The hardest part was getting the feet off the case. I have not had time to put it to use yet but I have one question. How come we can use the outputs as inputs without switching around any cables for the RCA outs? I am not very well versed on amp design/theory and was just wondering why it worked.

Because the original wireless input and the line out shared a common trace on the tone board. Once the wireless board's signal is removed, the line out feeds back through the tone board just like the wireless board's input did.

billbillw

ben62670 wrote: »

1.) Remove the daughter board.
2.) On the front board with the knobs remove the wires that lead to the inputs.
3.) Remove the wires that run from the front board to the main board.
4.) cut the wires from the RCA jacks near the front panel connector.
5.) Locate the input wires on the main board. They should be L G R. They are on the right side of the group of wires.
6.) Tie the input wires from the RCA's directly to the input wires on the main board.

This mod bypasses all the knobs, op-amps, resistors, and low quality caps that kill the SQ on these little amps. You will have no volume control with this mod. Your source will need variable outs. Such as an Ipod, computer, or a CD player with variable outs.

I had an idea after pmlewis asked about the wiring that allows us to use the line out for input.

I wanted to bypass the tone circuit, but I didn't want it to be permanent.
Why not hook the input wires that lead to the main board to the spot where the receiver board was hooked. These plugs all have the same pin diameter and they can be removed from the their plug and rearranged however you like. So this is what I did.

I took the three wires that corresponded to the L/G/R feed out of the larger plug. This can be done easily by using a small pin or paperclip to press on the retaining clip and easily pull them out of the plug.
Next, I took the spare jumper wire that came off the receiver board and removed one of the plug ends. I re-inserted the 3 pins into the empty plug and then inserted it into the spot where the receiver used to plug in. Since the input and line out shared a common trace, this effectively acts as a jumper to bypass the tone controls, volume controls, etc. No cutting, no soldering, no taping. Oh yeah. I also took the sleeve off of the spare wire and put it onto the input wires to make things look cleaner.

All done in about 10 minutes. Taking the tone control out removed any hum/buzz that was coming through the amp. Something in that circuit must have been picking up the transformer's magnetic field and turning it into ripple in the output.

billbillw

It should be noted that in this configuration (or any that bypasses the entire tone board), you are loosing a bit of overall gain. There is an opamp on the board that is being bypassed. Without that, I don't think an Ipod has enough output to really drive this amp to full power. A computer sound card might to better, but I haven't fully tested that setup yet.

Face

I agree. After bypassing the tone board, if I use my PDA as a source, the amp is hardly loud at all.

ben62670

I have been driving mine with an onboard sound card, and it has enough juice to drive it. I am curious if having it still hooked to the front panel has any adverse effects to sound level, and SQ even though the signal is not passing through it is still going to the board. My PDA was weak as well.
Ben

madmax

Face wrote: »

I agree. After bypassing the tone board, if I use my PDA as a source, the amp is hardly loud at all.

I didn't notice much difference. Must be something to do with impedances or something.
madmax

billbillw

ben62670 wrote: »

I am curious if having it still hooked to the front panel has any adverse effects to sound level, and SQ even though the signal is not passing through it is still going to the board.
Ben

I actually tried it using a set of pins to link the two plugs together versus having them hooked directly to the tone board. It sounded exactly the same. I ended up going with the arrangement in the photo because I trusted the connectors on the tone board more than a set of rigged up pins cut from a paper-clip

ben62670

billbillw wrote: »

I actually tried it using a set of pins to link the two plugs together versus having them hooked directly to the tone board. It sounded exactly the same. I ended up going with the arrangement in the photo because I trusted the connectors on the tone board more than a set of rigged up pins cut from a paper-clip

Cool it wasn't a derogatory question, but something I was truly curious about. Thanks Bill
Ben

billbillw

ben62670 wrote: »

Cool it wasn't a derogatory question, but something I was truly curious about. Thanks Bill
Ben

I didn't think it was derogatory. I was just letting you know I tried both ways and couldn't hear a difference. I was curious too. I still think I want to explore using part of the tone board and perhaps finding a way to bypass the tone controls and just keeping the balance and volume, but improving the quality of them. RadioShack sells a volume pot for about $4 that is supposed to be quite bit better than the stock one. I've got a slew of caps and opamps laying around too, so I might be able to make upgrades without spending much at all.

The reason I'd like to keep volume control is if I decide to use an external DAC running from the optical output on my motherboard versus having an external high end sound card.