Amp Deal of the Century!

MillerLiteScott

Sorry.

Long day.

Scott

fredv

MillerLiteScott wrote: »

Sorry.

Long day.

Scott

Me, too
This tube pre has gain, around 18dB (roughly 8x). It should be plenty to drive the little Accurian. I also found out that this RS amp loves higher impedance speakers. I thought the amp had enough gain, so I tried building a tube buffer. It didn't work out as the tube buffer had only 90% of the input .... When you are ready to add a tube stage, email me. I have plenty of spare parts to send you with the exception of the filament transformer.

MillerLiteScott

Well after many emails, free parts and pieces shipped from Fredv including 3 tubes, I have an operational Amp Deal of the Century with a tube pre-amp.

I could not have even thought about doing this without the help from Fred. Fred is a great example of Club Polk's true roots. Not only did he design the pre-amp, he supplied me with all the necessary parts, he coached me through the whole build. He encouraged me when I failed the first few times. Today I had a break through and the satisfaction of hearing the amp play for the first time was fantastic.

Thanks Fred.

Here are a few picture of my working bread board version before I start designing a chassis for it. I made the pre-amp using 2 PCB which helps with the design of the chassis because the pre-amp is now somewhat modular.

Frustration at times, but well worth it and a great learning experience. The DIY thing is really fun and I hope to learn a lot more.

maximillian

Nice pics. How would you characterize the sound?

MillerLiteScott

I am very pleased with the sound. The sound depends on which tube you use. I am still trying to figure out which one sound the best.

Scott

schwarcw

Very nice Scott! I've been watching closely what you guys are doing. I've got an upopened amp in the garage that I want to fool around with one of these days.

fredv

Hi Scott,

I knew you could fix it, congratulation!!!! I was just the cheerleader and really didn't do much. It was you, the brave soul, taking the risk to try my BS The improvement of sound quality probably may not that significant, but the feeling of accomplishment definitely sweetens the sound I hope you are having fun!!

ben62670

Well I blew a channel in my tube doing some stress test. I have backup though:)
Thanks Fred.
Ben

ben62670

Check your yahoo IM Fred:)

ben62670

Well I have raped two of these amps. I took a 4 1/2" angle grinder with a cut off wheel and cut the main board to remove the PS rectifier, and caps out. The voltages are 34vdc+-. I purchased a bunch of gainclone boards from Brian at chipamp.com, and stuffed them to his specs. I am driving my tweeters on my custom SDA's with this amp setup now. I had a GFA-555 driving them before and this is better sounding for the tweets. I have driven my custom monitor 4.6's with morel tweeters with them also. I have not tried to drive any serious low impedance speakers with these yet, but I am very pleased with the performance so far. There is only a few hours on it so far. I know things get better with time, but I am very pleased with the results so far. For the amount of the investment between the Accurian, and the chip amps I feel that you get a true HiFi amp that is quit capable.
Ben

fredv

ben62670 wrote: »

Well I have raped two of these amps. I took a 4 1/2" angle grinder with a cut off wheel and cut the main board to remove the PS rectifier, and caps out.

You are brutal :eek:

ben62670

Very effective, and it makes a clean cut. Next time I will do it outside

IamKai

Someone popped this is from the AUDIOKARMA site and it reminded me that the big thread was over here. I got to the point of using these for everything short of my main amps in critical areas. I would like to machine an aluminum case with a monster knobset and match the subwoofer outputs. It really needs a sub to work right, since it is cut off around 50 or so. In its original use, that was fine, but on a set of horns, it is pretty noticeable.
Figuring out how to get rid of that 50hz cutoff would really be the magic rod on this thing. Besides the bass missing, a set of Mirage M50's on one of these would satisfy 90% of all people out there. Also, a set of the small older transmission line REGA speakers make you smile on this 15 dollar wonder. (No diss to Polk...just reporting the best results I have had...as we all know synergy is 85% of the game in audio!)
Best wishes to you all and I would like to know if you are all still using these.:cheesygrin:

MrGlobe

What is the model #? Do they still sell these amps? I poked around the RS website as well as a handful of pages in this thread and didn't see a model number

schwarcw

I doubt that you will find these amps in a RS anywhere. The were discontinued and closed out 4 years ago. You may get luck on eBay or elsewhere.

IamKai

Okay, I made a phone call and will have a reply on Monday for a sweet case for these. A local metal shop will do up a full blown "Krell" style silver/gold theme and make the thing look like a million dollars.

Would anyone be interested in getting a sweet high end case for one of these? The more people into it who ordered, the less each unit would cost.

IamKai

by the way, this will include a blue or red power l.e.d. and a volume knob. Also, I am going to see about redoing the power switch so that it is a little quieter and more..."solid."

My thought is, the way these sound, if put in a case that looked like a Krell preamp...they would make a VERY coveted gift that college aged audio nuts would drool over in a dorm room.
I was also thinking about doing the tube input and making a case top specially for that purpose.
It would be pretty sweet to have the subwoofer controls also.
RadShack sold a simple rca plug switcher years ago that could be installed in the same case as well.
There are a few DIY instructions on the net that show even a starter how to wire up a switcher for the inputs.

The more and more I think about it, with a few hours of work, this could be turned into something very special for a gift to someone at the start of their audio adventure.

Face

I would think twice before dumping major money into one. They don't like low impedances nor will they play concert like SPL's.

madmax

I have not had mine hooked up since I moved a few years ago. I've been through tons of amps since then, probably time to pull it out of the moving box and see if it still sounds good.