Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Paramount => Topic started by: brucef on April 25, 2019, 01:10:50 AM
-
Just purchased a used pair of Paramount 300B amps. Hooked them up and there does not seem to be any issues with them. Couple of questions: what is the potentiometer for on each amp? And it seems like my current system with the Paramounts sounds kind of harsh and fatiguing. I have a Quickie pre hooked to the Paramounts that I have had for several years that I have used with no issues. Speakers are a pair of diy speakers at around 96db efficiency. They are single full range drivers in a ported cabinet. Prior to the Paramounts I was running a 1965 Fisher X-100 integrated that has been rebuilt. That Fisher setup sounds very very good. So, I am wondering if perhaps the Quickie is a bad match for the Paramounts or perhaps tubes?? The 300B tubes are Electro Harmonix and there is not a name on the 5670 tubes. I believe the Paramounts are stock builds. Looking for suggestions before I start spending money trying to smooth out the sound of these mono blocks.
-
If they are stock, the potentiometer on each amp is used along with a meter to adjust the DHT hum of the 300B to the lowest value.
-
I would post photos of the top and bottom of the Paramounts, as there are some mods that may need to be undone.
How fresh are the batteries on the Quickie?
My experience with vintage Fisher gear is that when you pile up 12AX7s, the high frequencies soften considerably. If you happen to have full range drivers that have rising response, the soft high frequency response of the Fisher may counteract the rising response of the speakers.
It's a lot of speculation without more details. Dead/dying tubes will also sound really harsh, but I wouldn't be running off to buy new ones until you test the ones you have.
-
Thanks for the responses. I will try new batteries in the Quickie to see if that helps. I am assuming that the Quickie should play well with the Paramounts. Here are some pictures of the amps. I am not really familiar with the 300B tube. Can it be tested ona standard tube tester. This is all new to me. Thanks
-
More pics
-
more pics
-
More pictures
-
Checked the batteries in the Quickie. The 9 volt batteries test at just under 8 volts and the D batteries test at just under 1.3 volts. Good enough or change?
-
I work off this thread, where PJ calls the D cells "tired" at 1.2 volts and has the 9 volts operating between 24-36v.
https://bottlehead.com/smf/index.php?topic=5241.msg50532#msg50532
-
Thanks for the battery info. Another question I thought of is how long do those mono blocks need to warm up?
-
Everything looks bone stock and well built on the amps, so that's a good start. The amps will take about 30 minutes to warm up.
-
Thanks. Good to know the amps are stock. How do I test the 300B tubes? I do have a couple of tube testers, but I did not see any info in the charts to test 300b tubes.
-
If they pull the correct voltage in the amps they are testing good. This is just as good a test as using a tube tester.
-
Thanks Doc. But I have no idea where to begin to test the voltage. I did find info that said to set the tester for the specs of a 2A3 tube, but set the filament voltage on 5 volts. Doing it that way the 300b's tested in the good range and the 5670 tubes tested strong. I listened again last night and to me, they sound thin, harsh and not much low end. Either something is amiss or it is just the nature of th amps?? This is my first experience with 300b amps. Or I am wondering if the Quickie pre is a bad match with the Paramounts. I have always used the Quickie with a ss amp and that combination was very good. After listening for a while I shut things down and hooked the Fisher back up to the same speakers etc, and it blew the Paramount Quickie combo away. Unfortunately I just recently sold a couple of pre amps and don't have anything else on hand to try with the Paramounts at this time. Sigh. Nor sure were to go from here. Any help is greatly appreciated. Thanks Bruce
-
Did the seller not include the manual?
Have you left them on for several hours to get them warmed up?
-
I did not receive the manual when I purchased the amps. Is that something I can order through BH? Also, no I have not let them warm up for several hours - only around 30 - 40 minutes before using.
-
Paramounts don't sound thin and harsh unless something is wrong. First guess is the output impedance setting is not optimal. You can order a manual from us. We are really booked with some things for the next few days but we'll be back at it on Monday. Eileen can help you then. You can reach her at queen at bottlehead dot com.
-
Hi Bruce, looks like you got a nice pair of Paramounts there. I have a question for you. What are you using for a source? DAC, CD player, turntable, tuner, tape, etc.? If you are using a turntable which cartridge and phono-pre are you using?
The "phono" input on your Fisher is not the same as an input on your Quickie. Could that explain the harsh and thin sound you are experiencing?
Sorry if this sounds obvious. But sometimes the obvious is overlooked.
-
For source I am using either a cd player or a streaming device with a built in dac, an Audioengine clone. Since I don't have a manual in my hands, I am kinda stuck. As Doc had mentioned things may need to be adjusted. I would like to know if the Quickie is a bad match for those amps, but no one has addressed that question yet.
-
The Quickie should work just fine with the Paramounts.
-
I received the manual yesterday for the Paramounts and I began reading through the build instructions and comparing to one of my amps. Things look good from what I can see. They are wired for 8ohm speakers.I checked resistance as per the instructions and everything seems to be good, with the exception of the resistance checks for the items marked with an asterick. Terminal strip 9, 19 and pin sockets B4 and B6. I will get a reading for a second and then it goes off. Is this normal? This is all new to me. Learning as I go. Thanks for the help.
-
The asterisk means that you don't want to see a zero or a really low number there, but there isn't really any consistency between meters for what will actually come out on those readings.
-
Thanks Paul. After your reply I did notice in the manual that it does mention that. Voltage checks will be over the weekend. I did listen to them the other day, and letting them warm up for a couple hours did seem to help with the overall sound.
-
Just finished checking voltage on the first amp. Results as follows:
Terminal strips Manual Mine
1 440 455
5 71 75
9 175 175
10 0 0
16 457 485
17 0 0
18 0 0
19 175 175
10k pot set to 175vdc
4 pin socket
A1 74.1 77
A2 440 455
A3 0 0
A4 69 72
Power Board
Red 3.1vac 2.8vac
Black 3.1vac 2.8vac
Kreg A 4.1 3.1
Kreg B 6.3 7
OA 300 301
OB 175 175
Are things close enough?
Thanks Bruce
-
With the meter you're using, what is the smallest AC scale?
It is unusual to see 2.8V instead of 3.1V for the driver tube heaters. This could be an issue of low line voltage, but you have some DC voltages that suggest that your line voltage might be slightly high (not a bad thing). If your meter only has a 200V and 500V scale for AC voltage, then the 2.8V reading wouldn't worry me.
-PB
-
The meter I am using does in fact only have a 200v and 500v setting for AC voltage.And, when I checked the second amp, it tested almost identical to the first amp in regards to all the measurements including the 2.8v reading.